diff options
Diffstat (limited to 'security/keys')
| -rw-r--r-- | security/keys/compat.c | 13 | ||||
| -rw-r--r-- | security/keys/gc.c | 14 | ||||
| -rw-r--r-- | security/keys/internal.h | 26 | ||||
| -rw-r--r-- | security/keys/key.c | 240 | ||||
| -rw-r--r-- | security/keys/keyctl.c | 278 | ||||
| -rw-r--r-- | security/keys/keyring.c | 231 | ||||
| -rw-r--r-- | security/keys/permission.c | 25 | ||||
| -rw-r--r-- | security/keys/proc.c | 10 | ||||
| -rw-r--r-- | security/keys/process_keys.c | 112 | ||||
| -rw-r--r-- | security/keys/request_key.c | 164 | ||||
| -rw-r--r-- | security/keys/request_key_auth.c | 30 |
11 files changed, 777 insertions, 366 deletions
diff --git a/security/keys/compat.c b/security/keys/compat.c index 3cedf6305179..07a5f35e3970 100644 --- a/security/keys/compat.c +++ b/security/keys/compat.c @@ -1,4 +1,4 @@ -/* compat.c: 32-bit compatibility syscall for 64-bit systems +/* 32-bit compatibility syscall for 64-bit systems * * Copyright (C) 2004-5 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) @@ -15,11 +15,12 @@ #include "internal.h" /* - * the key control system call, 32-bit compatibility version for 64-bit archs - * - this should only be called if the 64-bit arch uses weird pointers in - * 32-bit mode or doesn't guarantee that the top 32-bits of the argument - * registers on taking a 32-bit syscall are zero - * - if you can, you should call sys_keyctl directly + * The key control system call, 32-bit compatibility version for 64-bit archs + * + * This should only be called if the 64-bit arch uses weird pointers in 32-bit + * mode or doesn't guarantee that the top 32-bits of the argument registers on + * taking a 32-bit syscall are zero. If you can, you should call sys_keyctl() + * directly. */ asmlinkage long compat_sys_keyctl(u32 option, u32 arg2, u32 arg3, u32 arg4, u32 arg5) diff --git a/security/keys/gc.c b/security/keys/gc.c index a46e825cbf02..89df6b5f203c 100644 --- a/security/keys/gc.c +++ b/security/keys/gc.c @@ -32,8 +32,8 @@ static time_t key_gc_next_run = LONG_MAX; static time_t key_gc_new_timer; /* - * Schedule a garbage collection run - * - precision isn't particularly important + * Schedule a garbage collection run. + * - time precision isn't particularly important */ void key_schedule_gc(time_t gc_at) { @@ -61,8 +61,9 @@ static void key_gc_timer_func(unsigned long data) } /* - * Garbage collect pointers from a keyring - * - return true if we altered the keyring + * Garbage collect pointers from a keyring. + * + * Return true if we altered the keyring. */ static bool key_gc_keyring(struct key *keyring, time_t limit) __releases(key_serial_lock) @@ -107,9 +108,8 @@ do_gc: } /* - * Garbage collector for keys - * - this involves scanning the keyrings for dead, expired and revoked keys - * that have overstayed their welcome + * Garbage collector for keys. This involves scanning the keyrings for dead, + * expired and revoked keys that have overstayed their welcome */ static void key_garbage_collector(struct work_struct *work) { diff --git a/security/keys/internal.h b/security/keys/internal.h index 56a133d8f37d..edfa50dbd6f5 100644 --- a/security/keys/internal.h +++ b/security/keys/internal.h @@ -1,4 +1,4 @@ -/* internal.h: authentication token and access key management internal defs +/* Authentication token and access key management internal defs * * Copyright (C) 2003-5, 2007 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) @@ -35,10 +35,12 @@ extern struct key_type key_type_user; /*****************************************************************************/ /* - * keep track of keys for a user - * - this needs to be separate to user_struct to avoid a refcount-loop - * (user_struct pins some keyrings which pin this struct) - * - this also keeps track of keys under request from userspace for this UID + * Keep track of keys for a user. + * + * This needs to be separate to user_struct to avoid a refcount-loop + * (user_struct pins some keyrings which pin this struct). + * + * We also keep track of keys under request from userspace for this UID here. */ struct key_user { struct rb_node node; @@ -62,7 +64,7 @@ extern struct key_user *key_user_lookup(uid_t uid, extern void key_user_put(struct key_user *user); /* - * key quota limits + * Key quota limits. * - root has its own separate limits to everyone else */ extern unsigned key_quota_root_maxkeys; @@ -146,13 +148,13 @@ extern unsigned key_gc_delay; extern void keyring_gc(struct key *keyring, time_t limit); extern void key_schedule_gc(time_t expiry_at); -/* - * check to see whether permission is granted to use a key in the desired way - */ extern int key_task_permission(const key_ref_t key_ref, const struct cred *cred, key_perm_t perm); +/* + * Check to see whether permission is granted to use a key in the desired way. + */ static inline int key_permission(const key_ref_t key_ref, key_perm_t perm) { return key_task_permission(key_ref, current_cred(), perm); @@ -168,7 +170,7 @@ static inline int key_permission(const key_ref_t key_ref, key_perm_t perm) #define KEY_ALL 0x3f /* all the above permissions */ /* - * request_key authorisation + * Authorisation record for request_key(). */ struct request_key_auth { struct key *target_key; @@ -188,7 +190,7 @@ extern struct key *request_key_auth_new(struct key *target, extern struct key *key_get_instantiation_authkey(key_serial_t target_id); /* - * keyctl functions + * keyctl() functions */ extern long keyctl_get_keyring_ID(key_serial_t, int); extern long keyctl_join_session_keyring(const char __user *); @@ -214,7 +216,7 @@ extern long keyctl_get_security(key_serial_t keyid, char __user *buffer, extern long keyctl_session_to_parent(void); /* - * debugging key validation + * Debugging key validation */ #ifdef KEY_DEBUGGING extern void __key_check(const struct key *); diff --git a/security/keys/key.c b/security/keys/key.c index 3a92d7365870..84d4eb568b08 100644 --- a/security/keys/key.c +++ b/security/keys/key.c @@ -39,10 +39,10 @@ static DECLARE_RWSEM(key_types_sem); static void key_cleanup(struct work_struct *work); static DECLARE_WORK(key_cleanup_task, key_cleanup); -/* we serialise key instantiation and link */ +/* We serialise key instantiation and link */ DEFINE_MUTEX(key_construction_mutex); -/* any key who's type gets unegistered will be re-typed to this */ +/* Any key who's type gets unegistered will be re-typed to this */ static struct key_type key_type_dead = { .name = "dead", }; @@ -57,8 +57,8 @@ void __key_check(const struct key *key) #endif /* - * get the key quota record for a user, allocating a new record if one doesn't - * already exist + * Get the key quota record for a user, allocating a new record if one doesn't + * already exist. */ struct key_user *key_user_lookup(uid_t uid, struct user_namespace *user_ns) { @@ -66,7 +66,7 @@ struct key_user *key_user_lookup(uid_t uid, struct user_namespace *user_ns) struct rb_node *parent = NULL; struct rb_node **p; - try_again: +try_again: p = &key_user_tree.rb_node; spin_lock(&key_user_lock); @@ -123,16 +123,16 @@ struct key_user *key_user_lookup(uid_t uid, struct user_namespace *user_ns) goto out; /* okay - we found a user record for this UID */ - found: +found: atomic_inc(&user->usage); spin_unlock(&key_user_lock); kfree(candidate); - out: +out: return user; } /* - * dispose of a user structure + * Dispose of a user structure */ void key_user_put(struct key_user *user) { @@ -146,9 +146,8 @@ void key_user_put(struct key_user *user) } /* - * assign a key the next unique serial number - * - these are assigned randomly to avoid security issues through covert - * channel problems + * Allocate a serial number for a key. These are assigned randomly to avoid + * security issues through covert channel problems. */ static inline void key_alloc_serial(struct key *key) { @@ -208,14 +207,34 @@ serial_exists: } } -/* - * allocate a key of the specified type - * - update the user's quota to reflect the existence of the key - * - called from a key-type operation with key_types_sem read-locked by - * key_create_or_update() - * - this prevents unregistration of the key type - * - upon return the key is as yet uninstantiated; the caller needs to either - * instantiate the key or discard it before returning +/** + * key_alloc - Allocate a key of the specified type. + * @type: The type of key to allocate. + * @desc: The key description to allow the key to be searched out. + * @uid: The owner of the new key. + * @gid: The group ID for the new key's group permissions. + * @cred: The credentials specifying UID namespace. + * @perm: The permissions mask of the new key. + * @flags: Flags specifying quota properties. + * + * Allocate a key of the specified type with the attributes given. The key is + * returned in an uninstantiated state and the caller needs to instantiate the + * key before returning. + * + * The user's key count quota is updated to reflect the creation of the key and + * the user's key data quota has the default for the key type reserved. The + * instantiation function should amend this as necessary. If insufficient + * quota is available, -EDQUOT will be returned. + * + * The LSM security modules can prevent a key being created, in which case + * -EACCES will be returned. + * + * Returns a pointer to the new key if successful and an error code otherwise. + * + * Note that the caller needs to ensure the key type isn't uninstantiated. + * Internally this can be done by locking key_types_sem. Externally, this can + * be done by either never unregistering the key type, or making sure + * key_alloc() calls don't race with module unloading. */ struct key *key_alloc(struct key_type *type, const char *desc, uid_t uid, gid_t gid, const struct cred *cred, @@ -338,11 +357,18 @@ no_quota: key = ERR_PTR(-EDQUOT); goto error; } - EXPORT_SYMBOL(key_alloc); -/* - * reserve an amount of quota for the key's payload +/** + * key_payload_reserve - Adjust data quota reservation for the key's payload + * @key: The key to make the reservation for. + * @datalen: The amount of data payload the caller now wants. + * + * Adjust the amount of the owning user's key data quota that a key reserves. + * If the amount is increased, then -EDQUOT may be returned if there isn't + * enough free quota available. + * + * If successful, 0 is returned. */ int key_payload_reserve(struct key *key, size_t datalen) { @@ -376,12 +402,13 @@ int key_payload_reserve(struct key *key, size_t datalen) return ret; } - EXPORT_SYMBOL(key_payload_reserve); /* - * instantiate a key and link it into the target keyring atomically - * - called with the target keyring's semaphore writelocked + * Instantiate a key and link it into the target keyring atomically. Must be + * called with the target keyring's semaphore writelocked. The target key's + * semaphore need not be locked as instantiation is serialised by + * key_construction_mutex. */ static int __key_instantiate_and_link(struct key *key, const void *data, @@ -432,8 +459,21 @@ static int __key_instantiate_and_link(struct key *key, return ret; } -/* - * instantiate a key and link it into the target keyring atomically +/** + * key_instantiate_and_link - Instantiate a key and link it into the keyring. + * @key: The key to instantiate. + * @data: The data to use to instantiate the keyring. + * @datalen: The length of @data. + * @keyring: Keyring to create a link in on success (or NULL). + * @authkey: The authorisation token permitting instantiation. + * + * Instantiate a key that's in the uninstantiated state using the provided data + * and, if successful, link it in to the destination keyring if one is + * supplied. + * + * If successful, 0 is returned, the authorisation token is revoked and anyone + * waiting for the key is woken up. If the key was already instantiated, + * -EBUSY will be returned. */ int key_instantiate_and_link(struct key *key, const void *data, @@ -462,8 +502,24 @@ int key_instantiate_and_link(struct key *key, EXPORT_SYMBOL(key_instantiate_and_link); -/* - * negatively instantiate a key and link it into the target keyring atomically +/** + * key_negate_and_link - Negatively instantiate a key and link it into the keyring. + * @key: The key to instantiate. + * @timeout: The timeout on the negative key. + * @keyring: Keyring to create a link in on success (or NULL). + * @authkey: The authorisation token permitting instantiation. + * + * Negatively instantiate a key that's in the uninstantiated state and, if + * successful, set its timeout and link it in to the destination keyring if one + * is supplied. The key and any links to the key will be automatically garbage + * collected after the timeout expires. + * + * Negative keys are used to rate limit repeated request_key() calls by causing + * them to return -ENOKEY until the negative key expires. + * + * If successful, 0 is returned, the authorisation token is revoked and anyone + * waiting for the key is woken up. If the key was already instantiated, + * -EBUSY will be returned. */ int key_negate_and_link(struct key *key, unsigned timeout, @@ -525,15 +581,18 @@ int key_negate_and_link(struct key *key, EXPORT_SYMBOL(key_negate_and_link); /* - * do cleaning up in process context so that we don't have to disable - * interrupts all over the place + * Garbage collect keys in process context so that we don't have to disable + * interrupts all over the place. + * + * key_put() schedules this rather than trying to do the cleanup itself, which + * means key_put() doesn't have to sleep. */ static void key_cleanup(struct work_struct *work) { struct rb_node *_n; struct key *key; - go_again: +go_again: /* look for a dead key in the tree */ spin_lock(&key_serial_lock); @@ -547,7 +606,7 @@ static void key_cleanup(struct work_struct *work) spin_unlock(&key_serial_lock); return; - found_dead_key: +found_dead_key: /* we found a dead key - once we've removed it from the tree, we can * drop the lock */ rb_erase(&key->serial_node, &key_serial_tree); @@ -586,10 +645,13 @@ static void key_cleanup(struct work_struct *work) goto go_again; } -/* - * dispose of a reference to a key - * - when all the references are gone, we schedule the cleanup task to come and - * pull it out of the tree in definite process context +/** + * key_put - Discard a reference to a key. + * @key: The key to discard a reference from. + * + * Discard a reference to a key, and when all the references are gone, we + * schedule the cleanup task to come and pull it out of the tree in process + * context at some later time. */ void key_put(struct key *key) { @@ -600,11 +662,10 @@ void key_put(struct key *key) schedule_work(&key_cleanup_task); } } - EXPORT_SYMBOL(key_put); /* - * find a key by its serial number + * Find a key by its serial number. */ struct key *key_lookup(key_serial_t id) { @@ -626,11 +687,11 @@ struct key *key_lookup(key_serial_t id) goto found; } - not_found: +not_found: key = ERR_PTR(-ENOKEY); goto error; - found: +found: /* pretend it doesn't exist if it is awaiting deletion */ if (atomic_read(&key->usage) == 0) goto not_found; @@ -640,14 +701,16 @@ struct key *key_lookup(key_serial_t id) */ atomic_inc(&key->usage); - error: +error: spin_unlock(&key_serial_lock); return key; } /* - * find and lock the specified key type against removal - * - we return with the sem readlocked + * Find and lock the specified key type against removal. + * + * We return with the sem read-locked if successful. If the type wasn't + * available -ENOKEY is returned instead. */ struct key_type *key_type_lookup(const char *type) { @@ -665,12 +728,12 @@ struct key_type *key_type_lookup(const char *type) up_read(&key_types_sem); ktype = ERR_PTR(-ENOKEY); - found_kernel_type: +found_kernel_type: return ktype; } /* - * unlock a key type + * Unlock a key type locked by key_type_lookup(). */ void key_type_put(struct key_type *ktype) { @@ -678,9 +741,10 @@ void key_type_put(struct key_type *ktype) } /* - * attempt to update an existing key - * - the key has an incremented refcount - * - we need to put the key if we get an error + * Attempt to update an existing key. + * + * The key is given to us with an incremented refcount that we need to discard + * if we get an error. */ static inline key_ref_t __key_update(key_ref_t key_ref, const void *payload, size_t plen) @@ -717,9 +781,30 @@ error: goto out; } -/* - * search the specified keyring for a key of the same description; if one is - * found, update it, otherwise add a new one +/** + * key_create_or_update - Update or create and instantiate a key. + * @keyring_ref: A pointer to the destination keyring with possession flag. + * @type: The type of key. + * @description: The searchable description for the key. + * @payload: The data to use to instantiate or update the key. + * @plen: The length of @payload. + * @perm: The permissions mask for a new key. + * @flags: The quota flags for a new key. + * + * Search the destination keyring for a key of the same description and if one + * is found, update it, otherwise create and instantiate a new one and create a + * link to it from that keyring. + * + * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be + * concocted. + * + * Returns a pointer to the new key if successful, -ENODEV if the key type + * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the + * caller isn't permitted to modify the keyring or the LSM did not permit + * creation of the key. + * + * On success, the possession flag from the keyring ref will be tacked on to + * the key ref before it is returned. */ key_ref_t key_create_or_update(key_ref_t keyring_ref, const char *type, @@ -827,11 +912,20 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref, key_ref = __key_update(key_ref, payload, plen); goto error; } - EXPORT_SYMBOL(key_create_or_update); -/* - * update a key +/** + * key_update - Update a key's contents. + * @key_ref: The pointer (plus possession flag) to the key. + * @payload: The data to be used to update the key. + * @plen: The length of @payload. + * + * Attempt to update the contents of a key with the given payload data. The + * caller must be granted Write permission on the key. Negative keys can be + * instantiated by this method. + * + * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key + * type does not support updating. The key type may return other errors. */ int key_update(key_ref_t key_ref, const void *payload, size_t plen) { @@ -861,11 +955,16 @@ int key_update(key_ref_t key_ref, const void *payload, size_t plen) error: return ret; } - EXPORT_SYMBOL(key_update); -/* - * revoke a key +/** + * key_revoke - Revoke a key. + * @key: The key to be revoked. + * + * Mark a key as being revoked and ask the type to free up its resources. The + * revocation timeout is set and the key and all its links will be + * automatically garbage collected after key_gc_delay amount of time if they + * are not manually dealt with first. */ void key_revoke(struct key *key) { @@ -894,11 +993,15 @@ void key_revoke(struct key *key) up_write(&key->sem); } - EXPORT_SYMBOL(key_revoke); -/* - * register a type of key +/** + * register_key_type - Register a type of key. + * @ktype: The new key type. + * + * Register a new key type. + * + * Returns 0 on success or -EEXIST if a type of this name already exists. */ int register_key_type(struct key_type *ktype) { @@ -918,15 +1021,19 @@ int register_key_type(struct key_type *ktype) list_add(&ktype->link, &key_types_list); ret = 0; - out: +out: up_write(&key_types_sem); return ret; } - EXPORT_SYMBOL(register_key_type); -/* - * unregister a type of key +/** + * unregister_key_type - Unregister a type of key. + * @ktype: The key type. + * + * Unregister a key type and mark all the extant keys of this type as dead. + * Those keys of this type are then destroyed to get rid of their payloads and + * they and their links will be garbage collected as soon as possible. */ void unregister_key_type(struct key_type *ktype) { @@ -974,11 +1081,10 @@ void unregister_key_type(struct key_type *ktype) key_schedule_gc(0); } - EXPORT_SYMBOL(unregister_key_type); /* - * initialise the key management stuff + * Initialise the key management state. */ void __init key_init(void) { diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c index 83ec98b7e98d..31a0fd8189f1 100644 --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -1,4 +1,4 @@ -/* keyctl.c: userspace keyctl operations +/* Userspace key control operations * * Copyright (C) 2004-5 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) @@ -31,27 +31,24 @@ static int key_get_type_from_user(char *type, int ret; ret = strncpy_from_user(type, _type, len); - if (ret < 0) return ret; - if (ret == 0 || ret >= len) return -EINVAL; - if (type[0] == '.') return -EPERM; - type[len - 1] = '\0'; - return 0; } /* - * extract the description of a new key from userspace and either add it as a - * new key to the specified keyring or update a matching key in that keyring - * - the keyring must be writable - * - returns the new key's serial number - * - implements add_key() + * Extract the description of a new key from userspace and either add it as a + * new key to the specified keyring or update a matching key in that keyring. + * + * The keyring must be writable so that we can attach the key to it. + * + * If successful, the new key's serial number is returned, otherwise an error + * code is returned. */ SYSCALL_DEFINE5(add_key, const char __user *, _type, const char __user *, _description, @@ -134,14 +131,17 @@ SYSCALL_DEFINE5(add_key, const char __user *, _type, } /* - * search the process keyrings for a matching key - * - nested keyrings may also be searched if they have Search permission - * - if a key is found, it will be attached to the destination keyring if - * there's one specified - * - /sbin/request-key will be invoked if _callout_info is non-NULL - * - the _callout_info string will be passed to /sbin/request-key - * - if the _callout_info string is empty, it will be rendered as "-" - * - implements request_key() + * Search the process keyrings and keyring trees linked from those for a + * matching key. Keyrings must have appropriate Search permission to be + * searched. + * + * If a key is found, it will be attached to the destination keyring if there's + * one specified and the serial number of the key will be returned. + * + * If no key is found, /sbin/request-key will be invoked if _callout_info is + * non-NULL in an attempt to create a key. The _callout_info string will be + * passed to /sbin/request-key to aid with completing the request. If the + * _callout_info string is "" then it will be changed to "-". */ SYSCALL_DEFINE4(request_key, const char __user *, _type, const char __user *, _description, @@ -222,9 +222,11 @@ error: } /* - * get the ID of the specified process keyring - * - the keyring must have search permission to be found - * - implements keyctl(KEYCTL_GET_KEYRING_ID) + * Get the ID of the specified process keyring. + * + * The requested keyring must have search permission to be found. + * + * If successful, the ID of the requested keyring will be returned. */ long keyctl_get_keyring_ID(key_serial_t id, int create) { @@ -243,12 +245,17 @@ long keyctl_get_keyring_ID(key_serial_t id, int create) key_ref_put(key_ref); error: return ret; - -} /* end keyctl_get_keyring_ID() */ +} /* - * join the session keyring - * - implements keyctl(KEYCTL_JOIN_SESSION_KEYRING) + * Join a (named) session keyring. + * + * Create and join an anonymous session keyring or join a named session + * keyring, creating it if necessary. A named session keyring must have Search + * permission for it to be joined. Session keyrings without this permit will + * be skipped over. + * + * If successful, the ID of the joined session keyring will be returned. */ long keyctl_join_session_keyring(const char __user *_name) { @@ -274,9 +281,14 @@ error: } /* - * update a key's data payload - * - the key must be writable - * - implements keyctl(KEYCTL_UPDATE) + * Update a key's data payload from the given data. + * + * The key must grant the caller Write permission and the key type must support + * updating for this to work. A negative key can be positively instantiated + * with this call. + * + * If successful, 0 will be returned. If the key type does not support + * updating, then -EOPNOTSUPP will be returned. */ long keyctl_update_key(key_serial_t id, const void __user *_payload, @@ -321,9 +333,14 @@ error: } /* - * revoke a key - * - the key must be writable - * - implements keyctl(KEYCTL_REVOKE) + * Revoke a key. + * + * The key must be grant the caller Write or Setattr permission for this to + * work. The key type should give up its quota claim when revoked. The key + * and any links to the key will be automatically garbage collected after a + * certain amount of time (/proc/sys/kernel/keys/gc_delay). + * + * If successful, 0 is returned. */ long keyctl_revoke_key(key_serial_t id) { @@ -351,9 +368,11 @@ error: } /* - * clear the specified process keyring - * - the keyring must be writable - * - implements keyctl(KEYCTL_CLEAR) + * Clear the specified keyring, creating an empty process keyring if one of the + * special keyring IDs is used. + * + * The keyring must grant the caller Write permission for this to work. If + * successful, 0 will be returned. */ long keyctl_keyring_clear(key_serial_t ringid) { @@ -374,10 +393,15 @@ error: } /* - * link a key into a keyring - * - the keyring must be writable - * - the key must be linkable - * - implements keyctl(KEYCTL_LINK) + * Create a link from a keyring to a key if there's no matching key in the + * keyring, otherwise replace the link to the matching key with a link to the + * new key. + * + * The key must grant the caller Link permission and the the keyring must grant + * the caller Write permission. Furthermore, if an additional link is created, + * the keyring's quota will be extended. + * + * If successful, 0 will be returned. */ long keyctl_keyring_link(key_serial_t id, key_serial_t ringid) { @@ -406,10 +430,13 @@ error: } /* - * unlink the first attachment of a key from a keyring - * - the keyring must be writable - * - we don't need any permissions on the key - * - implements keyctl(KEYCTL_UNLINK) + * Unlink a key from a keyring. + * + * The keyring must grant the caller Write permission for this to work; the key + * itself need not grant the caller anything. If the last link to a key is + * removed then that key will be scheduled for destruction. + * + * If successful, 0 will be returned. */ long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid) { @@ -438,14 +465,17 @@ error: } /* - * describe a user key - * - the key must have view permission - * - if there's a buffer, we place up to buflen bytes of data into it - * - unless there's an error, we return the amount of description available, - * irrespective of how much we may have copied - * - the description is formatted thus: + * Return a description of a key to userspace. + * + * The key must grant the caller View permission for this to work. + * + * If there's a buffer, we place up to buflen bytes of data into it formatted + * in the following way: + * * type;uid;gid;perm;description<NUL> - * - implements keyctl(KEYCTL_DESCRIBE) + * + * If successful, we return the amount of description available, irrespective + * of how much we may have copied into the buffer. */ long keyctl_describe_key(key_serial_t keyid, char __user *buffer, @@ -516,13 +546,14 @@ error: } /* - * search the specified keyring for a matching key - * - the start keyring must be searchable - * - nested keyrings may also be searched if they are searchable - * - only keys with search permission may be found - * - if a key is found, it will be attached to the destination keyring if - * there's one specified - * - implements keyctl(KEYCTL_SEARCH) + * Search the specified keyring and any keyrings it links to for a matching + * key. Only keyrings that grant the caller Search permission will be searched + * (this includes the starting keyring). Only keys with Search permission can + * be found. + * + * If successful, the found key will be linked to the destination keyring if + * supplied and the key has Link permission, and the found key ID will be + * returned. */ long keyctl_keyring_search(key_serial_t ringid, const char __user *_type, @@ -609,13 +640,14 @@ error: } /* - * read a user key's payload - * - the keyring must be readable or the key must be searchable from the - * process's keyrings - * - if there's a buffer, we place up to buflen bytes of data into it - * - unless there's an error, we return the amount of data in the key, - * irrespective of how much we may have copied - * - implements keyctl(KEYCTL_READ) + * Read a key's payload. + * + * The key must either grant the caller Read permission, or it must grant the + * caller Search permission when searched for from the process keyrings. + * + * If successful, we place up to buflen bytes of data into the buffer, if one + * is provided, and return the amount of data that is available in the key, + * irrespective of how much we copied into the buffer. */ long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen) { @@ -669,10 +701,19 @@ error: } /* - * change the ownership of a key - * - the keyring owned by the changer - * - if the uid or gid is -1, then that parameter is not changed - * - implements keyctl(KEYCTL_CHOWN) + * Change the ownership of a key + * + * The key must grant the caller Setattr permission for this to work, though + * the key need not be fully instantiated yet. For the UID to be changed, or + * for the GID to be changed to a group the caller is not a member of, the + * caller must have sysadmin capability. If either uid or gid is -1 then that + * attribute is not changed. + * + * If the UID is to be changed, the new user must have sufficient quota to + * accept the key. The quota deduction will be removed from the old user to + * the new user should the attribute be changed. + * + * If successful, 0 will be returned. */ long keyctl_chown_key(key_serial_t id, uid_t uid, gid_t gid) { @@ -775,9 +816,11 @@ quota_overrun: } /* - * change the permission mask on a key - * - the keyring owned by the changer - * - implements keyctl(KEYCTL_SETPERM) + * Change the permission mask on a key. + * + * The key must grant the caller Setattr permission for this to work, though + * the key need not be fully instantiated yet. If the caller does not have + * sysadmin capability, it may only change the permission on keys that it owns. */ long keyctl_setperm_key(key_serial_t id, key_perm_t perm) { @@ -815,7 +858,8 @@ error: } /* - * get the destination keyring for instantiation + * Get the destination keyring for instantiation and check that the caller has + * Write permission on it. */ static long get_instantiation_keyring(key_serial_t ringid, struct request_key_auth *rka, @@ -852,7 +896,7 @@ static long get_instantiation_keyring(key_serial_t ringid, } /* - * change the request_key authorisation key on the current process + * Change the request_key authorisation key on the current process. */ static int keyctl_change_reqkey_auth(struct key *key) { @@ -869,8 +913,13 @@ static int keyctl_change_reqkey_auth(struct key *key) } /* - * instantiate the key with the specified payload, and, if one is given, link - * the key into the keyring + * Instantiate a key with the specified payload and link the key into the + * destination keyring if one is given. + * + * The caller must have the appropriate instantiation permit set for this to + * work (see keyctl_assume_authority). No other permissions are required. + * + * If successful, 0 will be returned. */ long keyctl_instantiate_key(key_serial_t id, const void __user *_payload, @@ -948,8 +997,19 @@ error: } /* - * negatively instantiate the key with the given timeout (in seconds), and, if - * one is given, link the key into the keyring + * Negatively instantiate the key with the given timeout (in seconds) and link + * the key into the destination keyring if one is given. + * + * The caller must have the appropriate instantiation permit set for this to + * work (see keyctl_assume_authority). No other permissions are required. + * + * The key and any links to the key will be automatically garbage collected + * after the timeout expires. + * + * Negative keys are used to rate limit repeated request_key() calls by causing + * them to return -ENOKEY until the negative key expires. + * + * If successful, 0 will be returned. */ long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid) { @@ -993,8 +1053,11 @@ error: } /* - * set the default keyring in which request_key() will cache keys - * - return the old setting + * Read or set the default keyring in which request_key() will cache keys and + * return the old setting. + * + * If a process keyring is specified then this will be created if it doesn't + * yet exist. The old setting will be returned if successful. */ long keyctl_set_reqkey_keyring(int reqkey_defl) { @@ -1050,7 +1113,16 @@ error: } /* - * set or clear the timeout for a key + * Set or clear the timeout on a key. + * + * Either the key must grant the caller Setattr permission or else the caller + * must hold an instantiation authorisation token for the key. + * + * The timeout is either 0 to clear the timeout, or a number of seconds from + * the current time. The key and any links to the key will be automatically + * garbage collected after the timeout expires. + * + * If successful, 0 is returned. */ long keyctl_set_timeout(key_serial_t id, unsigned timeout) { @@ -1105,7 +1177,21 @@ error: } /* - * assume the authority to instantiate the specified key + * Assume (or clear) the authority to instantiate the specified key. + * + * This sets the authoritative token currently in force for key instantiation. + * This must be done for a key to be instantiated. It has the effect of making + * available all the keys from the caller of the request_key() that created a + * key to request_key() calls made by the caller of this function. + * + * The caller must have the instantiation key in their process keyrings with a + * Search permission grant available to the caller. + * + * If the ID given is 0, then the setting will be cleared and 0 returned. + * + * If the ID given has a matching an authorisation key, then that key will be + * set and its ID will be returned. The authorisation key can be read to get + * the callout information passed to request_key(). */ long keyctl_assume_authority(key_serial_t id) { @@ -1145,12 +1231,14 @@ error: } /* - * get the security label of a key - * - the key must grant us view permission - * - if there's a buffer, we place up to buflen bytes of data into it - * - unless there's an error, we return the amount of information available, - * irrespective of how much we may have copied (including the terminal NUL) - * - implements keyctl(KEYCTL_GET_SECURITY) + * Get a key's the LSM security label. + * + * The key must grant the caller View permission for this to work. + * + * If there's a buffer, then up to buflen bytes of data will be placed into it. + * + * If successful, the amount of information available will be returned, + * irrespective of how much was copied (including the terminal NUL). */ long keyctl_get_security(key_serial_t keyid, char __user *buffer, @@ -1205,10 +1293,16 @@ long keyctl_get_security(key_serial_t keyid, } /* - * attempt to install the calling process's session keyring on the process's - * parent process - * - the keyring must exist and must grant us LINK permission - * - implements keyctl(KEYCTL_SESSION_TO_PARENT) + * Attempt to install the calling process's session keyring on the process's + * parent process. + * + * The keyring must exist and must grant the caller LINK permission, and the + * parent process must be single-threaded and must have the same effective + * ownership as this process and mustn't be SUID/SGID. + * + * The keyring will be emplaced on the parent when it next resumes userspace. + * + * If successful, 0 will be returned. */ long keyctl_session_to_parent(void) { @@ -1312,7 +1406,7 @@ error_keyring: } /* - * the key control system call + * The key control system call */ SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3, unsigned long, arg4, unsigned long, arg5) diff --git a/security/keys/keyring.c b/security/keys/keyring.c index 0a2b8e916d97..92024ed12e0a 100644 --- a/security/keys/keyring.c +++ b/security/keys/keyring.c @@ -26,13 +26,13 @@ rwsem_is_locked((struct rw_semaphore *)&(keyring)->sem))) /* - * when plumbing the depths of the key tree, this sets a hard limit set on how - * deep we're willing to go + * When plumbing the depths of the key tree, this sets a hard limit + * set on how deep we're willing to go. */ #define KEYRING_SEARCH_MAX_DEPTH 6 /* - * we keep all named keyrings in a hash to speed looking them up + * We keep all named keyrings in a hash to speed looking them up. */ #define KEYRING_NAME_HASH_SIZE (1 << 5) @@ -50,7 +50,9 @@ static inline unsigned keyring_hash(const char *desc) } /* - * the keyring type definition + * The keyring key type definition. Keyrings are simply keys of this type and + * can be treated as ordinary keys in addition to having their own special + * operations. */ static int keyring_instantiate(struct key *keyring, const void *data, size_t datalen); @@ -71,18 +73,17 @@ struct key_type key_type_keyring = { .describe = keyring_describe, .read = keyring_read, }; - EXPORT_SYMBOL(key_type_keyring); /* - * semaphore to serialise link/link calls to prevent two link calls in parallel - * introducing a cycle + * Semaphore to serialise link/link calls to prevent two link calls in parallel + * introducing a cycle. */ static DECLARE_RWSEM(keyring_serialise_link_sem); /* - * publish the name of a keyring so that it can be found by name (if it has - * one) + * Publish the name of a keyring so that it can be found by name (if it has + * one). */ static void keyring_publish_name(struct key *keyring) { @@ -104,8 +105,9 @@ static void keyring_publish_name(struct key *keyring) } /* - * initialise a keyring - * - we object if we were given any data + * Initialise a keyring. + * + * Returns 0 on success, -EINVAL if given any data. */ static int keyring_instantiate(struct key *keyring, const void *data, size_t datalen) @@ -123,7 +125,7 @@ static int keyring_instantiate(struct key *keyring, } /* - * match keyrings on their name + * Match keyrings on their name */ static int keyring_match(const struct key *keyring, const void *description) { @@ -132,7 +134,8 @@ static int keyring_match(const struct key *keyring, const void *description) } /* - * dispose of the data dangling from the corpse of a keyring + * Clean up a keyring when it is destroyed. Unpublish its name if it had one + * and dispose of its data. */ static void keyring_destroy(struct key *keyring) { @@ -160,7 +163,7 @@ static void keyring_destroy(struct key *keyring) } /* - * describe the keyring + * Describe a keyring for /proc. */ static void keyring_describe(const struct key *keyring, struct seq_file *m) { @@ -181,8 +184,9 @@ static void keyring_describe(const struct key *keyring, struct seq_file *m) } /* - * read a list of key IDs from the keyring's contents - * - the keyring's semaphore is read-locked + * Read a list of key IDs from the keyring's contents in binary form + * + * The keyring's semaphore is read-locked by the caller. */ static long keyring_read(const struct key *keyring, char __user *buffer, size_t buflen) @@ -233,7 +237,7 @@ error: } /* - * allocate a keyring and link into the destination keyring + * Allocate a keyring and link into the destination keyring. */ struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid, const struct cred *cred, unsigned long flags, @@ -258,16 +262,40 @@ struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid, return keyring; } -/* - * search the supplied keyring tree for a key that matches the criterion - * - perform a breadth-then-depth search up to the prescribed limit - * - we only find keys on which we have search permission - * - we use the supplied match function to see if the description (or other - * feature of interest) matches - * - we rely on RCU to prevent the keyring lists from disappearing on us - * - we return -EAGAIN if we didn't find any matching key - * - we return -ENOKEY if we only found negative matching keys - * - we propagate the possession attribute from the keyring ref to the key ref +/** + * keyring_search_aux - Search a keyring tree for a key matching some criteria + * @keyring_ref: A pointer to the keyring with possession indicator. + * @cred: The credentials to use for permissions checks. + * @type: The type of key to search for. + * @description: Parameter for @match. + * @match: Function to rule on whether or not a key is the one required. + * + * Search the supplied keyring tree for a key that matches the criteria given. + * The root keyring and any linked keyrings must grant Search permission to the + * caller to be searchable and keys can only be found if they too grant Search + * to the caller. The possession flag on the root keyring pointer controls use + * of the possessor bits in permissions checking of the entire tree. In + * addition, the LSM gets to forbid keyring searches and key matches. + * + * The search is performed as a breadth-then-depth search up to the prescribed + * limit (KEYRING_SEARCH_MAX_DEPTH). + * + * Keys are matched to the type provided and are then filtered by the match + * function, which is given the description to use in any way it sees fit. The + * match function may use any attributes of a key that it wishes to to + * determine the match. Normally the match function from the key type would be + * used. + * + * RCU is used to prevent the keyring key lists from disappearing without the + * need to take lots of locks. + * + * Returns a pointer to the found key and increments the key usage count if + * successful; -EAGAIN if no matching keys were found, or if expired or revoked + * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the + * specified keyring wasn't a keyring. + * + * In the case of a successful return, the possession attribute from + * @keyring_ref is propagated to the returned key reference. */ key_ref_t keyring_search_aux(key_ref_t keyring_ref, const struct cred *cred, @@ -431,13 +459,14 @@ error: return key_ref; } -/* - * search the supplied keyring tree for a key that matches the criterion - * - perform a breadth-then-depth search up to the prescribed limit - * - we only find keys on which we have search permission - * - we readlock the keyrings as we search down the tree - * - we return -EAGAIN if we didn't find any matching key - * - we return -ENOKEY if we only found negative matching keys +/** + * keyring_search - Search the supplied keyring tree for a matching key + * @keyring: The root of the keyring tree to be searched. + * @type: The type of keyring we want to find. + * @description: The name of the keyring we want to find. + * + * As keyring_search_aux() above, but using the current task's credentials and + * type's default matching function. */ key_ref_t keyring_search(key_ref_t keyring, struct key_type *type, @@ -449,13 +478,22 @@ key_ref_t keyring_search(key_ref_t keyring, return keyring_search_aux(keyring, current->cred, type, description, type->match); } - EXPORT_SYMBOL(keyring_search); /* - * search the given keyring only (no recursion) - * - keyring must be locked by caller - * - caller must guarantee that the keyring is a keyring + * Search the given keyring only (no recursion). + * + * The caller must guarantee that the keyring is a keyring and that the + * permission is granted to search the keyring as no check is made here. + * + * RCU is used to make it unnecessary to lock the keyring key list here. + * + * Returns a pointer to the found key with usage count incremented if + * successful and returns -ENOKEY if not found. Revoked keys and keys not + * providing the requested permission are skipped over. + * + * If successful, the possession indicator is propagated from the keyring ref + * to the returned key reference. */ key_ref_t __keyring_search_one(key_ref_t keyring_ref, const struct key_type *ktype, @@ -498,9 +536,15 @@ found: } /* - * find a keyring with the specified name - * - all named keyrings are searched - * - normally only finds keyrings with search permission for the current process + * Find a keyring with the specified name. + * + * All named keyrings in the current user namespace are searched, provided they + * grant Search permission directly to the caller (unless this check is + * skipped). Keyrings whose usage points have reached zero or who have been + * revoked are skipped. + * + * Returns a pointer to the keyring with the keyring's refcount having being + * incremented on success. -ENOKEY is returned if a key could not be found. */ struct key *find_keyring_by_name(const char *name, bool skip_perm_check) { @@ -551,10 +595,11 @@ out: } /* - * see if a cycle will will be created by inserting acyclic tree B in acyclic - * tree A at the topmost level (ie: as a direct child of A) - * - since we are adding B to A at the top level, checking for cycles should - * just be a matter of seeing if node A is somewhere in tree B + * See if a cycle will will be created by inserting acyclic tree B in acyclic + * tree A at the topmost level (ie: as a direct child of A). + * + * Since we are adding B to A at the top level, checking for cycles should just + * be a matter of seeing if node A is somewhere in tree B. */ static int keyring_detect_cycle(struct key *A, struct key *B) { @@ -637,7 +682,7 @@ cycle_detected: } /* - * dispose of a keyring list after the RCU grace period, freeing the unlinked + * Dispose of a keyring list after the RCU grace period, freeing the unlinked * key */ static void keyring_unlink_rcu_disposal(struct rcu_head *rcu) @@ -651,7 +696,7 @@ static void keyring_unlink_rcu_disposal(struct rcu_head *rcu) } /* - * preallocate memory so that a key can be linked into to a keyring + * Preallocate memory so that a key can be linked into to a keyring. */ int __key_link_begin(struct key *keyring, const struct key_type *type, const char *description, @@ -768,10 +813,10 @@ error_krsem: } /* - * check already instantiated keys aren't going to be a problem - * - the caller must have called __key_link_begin() - * - don't need to call this for keys that were created since __key_link_begin() - * was called + * Check already instantiated keys aren't going to be a problem. + * + * The caller must have called __key_link_begin(). Don't need to call this for + * keys that were created since __key_link_begin() was called. */ int __key_link_check_live_key(struct key *keyring, struct key *key) { @@ -783,9 +828,12 @@ int __key_link_check_live_key(struct key *keyring, struct key *key) } /* - * link a key into to a keyring - * - must be called with __key_link_begin() having being called - * - discard already extant link to matching key if there is one + * Link a key into to a keyring. + * + * Must be called with __key_link_begin() having being called. Discards any + * already extant link to matching key if there is one, so that each keyring + * holds at most one link to any given key of a particular type+description + * combination. */ void __key_link(struct key *keyring, struct key *key, struct keyring_list **_prealloc) @@ -828,8 +876,9 @@ void __key_link(struct key *keyring, struct key *key, } /* - * finish linking a key into to a keyring - * - must be called with __key_link_begin() having being called + * Finish linking a key into to a keyring. + * + * Must be called with __key_link_begin() having being called. */ void __key_link_end(struct key *keyring, struct key_type *type, struct keyring_list *prealloc) @@ -850,8 +899,25 @@ void __key_link_end(struct key *keyring, struct key_type *type, up_write(&keyring->sem); } -/* - * link a key to a keyring +/** + * key_link - Link a key to a keyring + * @keyring: The keyring to make the link in. + * @key: The key to link to. + * + * Make a link in a keyring to a key, such that the keyring holds a reference + * on that key and the key can potentially be found by searching that keyring. + * + * This function will write-lock the keyring's semaphore and will consume some + * of the user's key data quota to hold the link. + * + * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, + * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is + * full, -EDQUOT if there is insufficient key data quota remaining to add + * another link or -ENOMEM if there's insufficient memory. + * + * It is assumed that the caller has checked that it is permitted for a link to + * be made (the keyring should have Write permission and the key Link + * permission). */ int key_link(struct key *keyring, struct key *key) { @@ -871,11 +937,24 @@ int key_link(struct key *keyring, struct key *key) return ret; } - EXPORT_SYMBOL(key_link); -/* - * unlink the first link to a key from a keyring +/** + * key_unlink - Unlink the first link to a key from a keyring. + * @keyring: The keyring to remove the link from. + * @key: The key the link is to. + * + * Remove a link from a keyring to a key. + * + * This function will write-lock the keyring's semaphore. + * + * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if + * the key isn't linked to by the keyring or -ENOMEM if there's insufficient + * memory. + * + * It is assumed that the caller has checked that it is permitted for a link to + * be removed (the keyring should have Write permission; no permissions are + * required on the key). */ int key_unlink(struct key *keyring, struct key *key) { @@ -944,12 +1023,11 @@ nomem: up_write(&keyring->sem); goto error; } - EXPORT_SYMBOL(key_unlink); /* - * dispose of a keyring list after the RCU grace period, releasing the keys it - * links to + * Dispose of a keyring list after the RCU grace period, releasing the keys it + * links to. */ static void keyring_clear_rcu_disposal(struct rcu_head *rcu) { @@ -964,9 +1042,13 @@ static void keyring_clear_rcu_disposal(struct rcu_head *rcu) kfree(klist); } -/* - * clear the specified process keyring - * - implements keyctl(KEYCTL_CLEAR) +/** + * keyring_clear - Clear a keyring + * @keyring: The keyring to clear. + * + * Clear the contents of the specified keyring. + * + * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring. */ int keyring_clear(struct key *keyring) { @@ -999,12 +1081,12 @@ int keyring_clear(struct key *keyring) return ret; } - EXPORT_SYMBOL(keyring_clear); /* - * dispose of the links from a revoked keyring - * - called with the key sem write-locked + * Dispose of the links from a revoked keyring. + * + * This is called with the key sem write-locked. */ static void keyring_revoke(struct key *keyring) { @@ -1022,7 +1104,7 @@ static void keyring_revoke(struct key *keyring) } /* - * Determine whether a key is dead + * Determine whether a key is dead. */ static bool key_is_dead(struct key *key, time_t limit) { @@ -1031,7 +1113,12 @@ static bool key_is_dead(struct key *key, time_t limit) } /* - * Collect garbage from the contents of a keyring + * Collect garbage from the contents of a keyring, replacing the old list with + * a new one with the pointers all shuffled down. + * + * Dead keys are classed as oned that are flagged as being dead or are revoked, + * expired or negative keys that were revoked or expired before the specified + * limit. */ void keyring_gc(struct key *keyring, time_t limit) { diff --git a/security/keys/permission.c b/security/keys/permission.c index 6284b1496c29..c35b5229e3cd 100644 --- a/security/keys/permission.c +++ b/security/keys/permission.c @@ -1,4 +1,4 @@ -/* permission.c: key permission determination +/* Key permission checking * * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) @@ -15,15 +15,17 @@ /** * key_task_permission - Check a key can be used - * @key_ref: The key to check - * @cred: The credentials to use - * @perm: The permissions to check for + * @key_ref: The key to check. + * @cred: The credentials to use. + * @perm: The permissions to check for. * * Check to see whether permission is granted to use a key in the desired way, * but permit the security modules to override. * - * The caller must hold either a ref on cred or must hold the RCU readlock or a - * spinlock. + * The caller must hold either a ref on cred or must hold the RCU readlock. + * + * Returns 0 if successful, -EACCES if access is denied based on the + * permissions bits or the LSM check. */ int key_task_permission(const key_ref_t key_ref, const struct cred *cred, key_perm_t perm) @@ -79,11 +81,15 @@ use_these_perms: /* let LSM be the final arbiter */ return security_key_permission(key_ref, cred, perm); } - EXPORT_SYMBOL(key_task_permission); -/* - * validate a key +/** + * key_validate - Validate a key. + * @key: The key to be validated. + * + * Check that a key is valid, returning 0 if the key is okay, -EKEYREVOKED if + * the key's type has been removed or if the key has been revoked or + * -EKEYEXPIRED if the key has expired. */ int key_validate(struct key *key) { @@ -109,5 +115,4 @@ int key_validate(struct key *key) error: return ret; } - EXPORT_SYMBOL(key_validate); diff --git a/security/keys/proc.c b/security/keys/proc.c index ad5f64e1b320..525cf8a29cdd 100644 --- a/security/keys/proc.c +++ b/security/keys/proc.c @@ -1,4 +1,4 @@ -/* proc.c: proc files for key database enumeration +/* procfs files for key database enumeration * * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) @@ -61,7 +61,7 @@ static const struct file_operations proc_key_users_fops = { }; /* - * declare the /proc files + * Declare the /proc files. */ static int __init key_proc_init(void) { @@ -83,7 +83,8 @@ static int __init key_proc_init(void) __initcall(key_proc_init); /* - * implement "/proc/keys" to provides a list of the keys on the system + * Implement "/proc/keys" to provide a list of the keys on the system that + * grant View permission to the caller. */ #ifdef CONFIG_KEYS_DEBUG_PROC_KEYS @@ -291,7 +292,8 @@ static struct rb_node *key_user_first(struct rb_root *r) } /* - * implement "/proc/key-users" to provides a list of the key users + * Implement "/proc/key-users" to provides a list of the key users and their + * quotas. */ static int proc_key_users_open(struct inode *inode, struct file *file) { diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c index ea55cf9acf36..930634e45149 100644 --- a/security/keys/process_keys.c +++ b/security/keys/process_keys.c @@ -1,4 +1,4 @@ -/* Management of a process's keyrings +/* Manage a process's keyrings * * Copyright (C) 2004-2005, 2008 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) @@ -21,13 +21,13 @@ #include <asm/uaccess.h> #include "internal.h" -/* session keyring create vs join semaphore */ +/* Session keyring create vs join semaphore */ static DEFINE_MUTEX(key_session_mutex); -/* user keyring creation semaphore */ +/* User keyring creation semaphore */ static DEFINE_MUTEX(key_user_keyring_mutex); -/* the root user's tracking struct */ +/* The root user's tracking struct */ struct key_user root_key_user = { .usage = ATOMIC_INIT(3), .cons_lock = __MUTEX_INITIALIZER(root_key_user.cons_lock), @@ -39,7 +39,7 @@ struct key_user root_key_user = { }; /* - * install user and user session keyrings for a particular UID + * Install the user and user session keyrings for the current process's UID. */ int install_user_keyrings(void) { @@ -121,7 +121,8 @@ error: } /* - * install a fresh thread keyring directly to new credentials + * Install a fresh thread keyring directly to new credentials. This keyring is + * allowed to overrun the quota. */ int install_thread_keyring_to_cred(struct cred *new) { @@ -137,7 +138,7 @@ int install_thread_keyring_to_cred(struct cred *new) } /* - * install a fresh thread keyring, discarding the old one + * Install a fresh thread keyring, discarding the old one. */ static int install_thread_keyring(void) { @@ -160,9 +161,10 @@ static int install_thread_keyring(void) } /* - * install a process keyring directly to a credentials struct - * - returns -EEXIST if there was already a process keyring, 0 if one installed, - * and other -ve on any other error + * Install a process keyring directly to a credentials struct. + * + * Returns -EEXIST if there was already a process keyring, 0 if one installed, + * and other value on any other error */ int install_process_keyring_to_cred(struct cred *new) { @@ -191,8 +193,11 @@ int install_process_keyring_to_cred(struct cred *new) } /* - * make sure a process keyring is installed - * - we + * Make sure a process keyring is installed for the current process. The + * existing process keyring is not replaced. + * + * Returns 0 if there is a process keyring by the end of this function, some + * error otherwise. */ static int install_process_keyring(void) { @@ -213,7 +218,7 @@ static int install_process_keyring(void) } /* - * install a session keyring directly to a credentials struct + * Install a session keyring directly to a credentials struct. */ int install_session_keyring_to_cred(struct cred *cred, struct key *keyring) { @@ -253,8 +258,8 @@ int install_session_keyring_to_cred(struct cred *cred, struct key *keyring) } /* - * install a session keyring, discarding the old one - * - if a keyring is not supplied, an empty one is invented + * Install a session keyring, discarding the old one. If a keyring is not + * supplied, an empty one is invented. */ static int install_session_keyring(struct key *keyring) { @@ -275,7 +280,7 @@ static int install_session_keyring(struct key *keyring) } /* - * the filesystem user ID changed + * Handle the fsuid changing. */ void key_fsuid_changed(struct task_struct *tsk) { @@ -289,7 +294,7 @@ void key_fsuid_changed(struct task_struct *tsk) } /* - * the filesystem group ID changed + * Handle the fsgid changing. */ void key_fsgid_changed(struct task_struct *tsk) { @@ -303,11 +308,25 @@ void key_fsgid_changed(struct task_struct *tsk) } /* - * search only my process keyrings for the first matching key - * - we use the supplied match function to see if the description (or other - * feature of interest) matches - * - we return -EAGAIN if we didn't find any matching key - * - we return -ENOKEY if we found only negative matching keys + * Search the process keyrings attached to the supplied cred for the first + * matching key. + * + * The search criteria are the type and the match function. The description is + * given to the match function as a parameter, but doesn't otherwise influence + * the search. Typically the match function will compare the description + * parameter to the key's description. + * + * This can only search keyrings that grant Search permission to the supplied + * credentials. Keyrings linked to searched keyrings will also be searched if + * they grant Search permission too. Keys can only be found if they grant + * Search permission to the credentials. + * + * Returns a pointer to the key with the key usage count incremented if + * successful, -EAGAIN if we didn't find any matching key or -ENOKEY if we only + * matched negative keys. + * + * In the case of a successful return, the possession attribute is set on the + * returned key reference. */ key_ref_t search_my_process_keyrings(struct key_type *type, const void *description, @@ -423,11 +442,12 @@ found: } /* - * search the process keyrings for the first matching key - * - we use the supplied match function to see if the description (or other - * feature of interest) matches - * - we return -EAGAIN if we didn't find any matching key - * - we return -ENOKEY if we found only negative matching keys + * Search the process keyrings attached to the supplied cred for the first + * matching key in the manner of search_my_process_keyrings(), but also search + * the keys attached to the assumed authorisation key using its credentials if + * one is available. + * + * Return same as search_my_process_keyrings(). */ key_ref_t search_process_keyrings(struct key_type *type, const void *description, @@ -485,7 +505,7 @@ found: } /* - * see if the key we're looking at is the target key + * See if the key we're looking at is the target key. */ int lookup_user_key_possessed(const struct key *key, const void *target) { @@ -493,9 +513,22 @@ int lookup_user_key_possessed(const struct key *key, const void *target) } /* - * lookup a key given a key ID from userspace with a given permissions mask - * - don't create special keyrings unless so requested - * - partially constructed keys aren't found unless requested + * Look up a key ID given us by userspace with a given permissions mask to get + * the key it refers to. + * + * Flags can be passed to request that special keyrings be created if referred + * to directly, to permit partially constructed keys to be found and to skip + * validity and permission checks on the found key. + * + * Returns a pointer to the key with an incremented usage count if successful; + * -EINVAL if the key ID is invalid; -ENOKEY if the key ID does not correspond + * to a key or the best found key was a negative key; -EKEYREVOKED or + * -EKEYEXPIRED if the best found key was revoked or expired; -EACCES if the + * found key doesn't grant the requested permit or the LSM denied access to it; + * or -ENOMEM if a special keyring couldn't be created. + * + * In the case of a successful return, the possession attribute is set on the + * returned key reference. */ key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags, key_perm_t perm) @@ -703,10 +736,15 @@ reget_creds: } /* - * join the named keyring as the session keyring if possible, or attempt to - * create a new one of that name if not - * - if the name is NULL, an empty anonymous keyring is installed instead - * - named session keyring joining is done with a semaphore held + * Join the named keyring as the session keyring if possible else attempt to + * create a new one of that name and join that. + * + * If the name is NULL, an empty anonymous keyring will be installed as the + * session keyring. + * + * Named session keyrings are joined with a semaphore held to prevent the + * keyrings from going away whilst the attempt is made to going them and also + * to prevent a race in creating compatible session keyrings. */ long join_session_keyring(const char *name) { @@ -778,8 +816,8 @@ error: } /* - * Replace a process's session keyring when that process resumes userspace on - * behalf of one of its children + * Replace a process's session keyring on behalf of one of its children when + * the target process is about to resume userspace execution. */ void key_replace_session_keyring(void) { diff --git a/security/keys/request_key.c b/security/keys/request_key.c index 0ea52d25a6bd..9a7fb3914b27 100644 --- a/security/keys/request_key.c +++ b/security/keys/request_key.c @@ -39,8 +39,14 @@ static int key_wait_bit_intr(void *flags) return signal_pending(current) ? -ERESTARTSYS : 0; } -/* - * call to complete the construction of a key +/** + * complete_request_key - Complete the construction of a key. + * @cons: The key construction record. + * @error: The success or failute of the construction. + * + * Complete the attempt to construct a key. The key will be negated + * if an error is indicated. The authorisation key will be revoked + * unconditionally. */ void complete_request_key(struct key_construction *cons, int error) { @@ -58,23 +64,33 @@ void complete_request_key(struct key_construction *cons, int error) } EXPORT_SYMBOL(complete_request_key); +/* + * Initialise a usermode helper that is going to have a specific session + * keyring. + * + * This is called in context of freshly forked kthread before kernel_execve(), + * so we can simply install the desired session_keyring at this point. + */ static int umh_keys_init(struct subprocess_info *info) { struct cred *cred = (struct cred*)current_cred(); struct key *keyring = info->data; - /* - * This is called in context of freshly forked kthread before - * kernel_execve(), we can just change our ->session_keyring. - */ + return install_session_keyring_to_cred(cred, keyring); } +/* + * Clean up a usermode helper with session keyring. + */ static void umh_keys_cleanup(struct subprocess_info *info) { struct key *keyring = info->data; key_put(keyring); } +/* + * Call a usermode helper with a specific session keyring. + */ static int call_usermodehelper_keys(char *path, char **argv, char **envp, struct key *session_keyring, enum umh_wait wait) { @@ -91,7 +107,7 @@ static int call_usermodehelper_keys(char *path, char **argv, char **envp, } /* - * request userspace finish the construction of a key + * Request userspace finish the construction of a key * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>" */ static int call_sbin_request_key(struct key_construction *cons, @@ -198,8 +214,9 @@ error_alloc: } /* - * call out to userspace for key construction - * - we ignore program failure and go on key status instead + * Call out to userspace for key construction. + * + * Program failure is ignored in favour of key status. */ static int construct_key(struct key *key, const void *callout_info, size_t callout_len, void *aux, @@ -246,9 +263,10 @@ static int construct_key(struct key *key, const void *callout_info, } /* - * get the appropriate destination keyring for the request - * - we return whatever keyring we select with an extra reference upon it which - * the caller must release + * Get the appropriate destination keyring for the request. + * + * The keyring selected is returned with an extra reference upon it which the + * caller must release. */ static void construct_get_dest_keyring(struct key **_dest_keyring) { @@ -321,9 +339,11 @@ static void construct_get_dest_keyring(struct key **_dest_keyring) } /* - * allocate a new key in under-construction state and attempt to link it in to - * the requested place - * - may return a key that's already under construction instead + * Allocate a new key in under-construction state and attempt to link it in to + * the requested keyring. + * + * May return a key that's already under construction instead if there was a + * race between two thread calling request_key(). */ static int construct_alloc_key(struct key_type *type, const char *description, @@ -414,7 +434,7 @@ alloc_failed: } /* - * commence key construction + * Commence key construction. */ static struct key *construct_key_and_link(struct key_type *type, const char *description, @@ -465,12 +485,32 @@ construction_failed: return ERR_PTR(ret); } -/* - * request a key - * - search the process's keyrings - * - check the list of keys being created or updated - * - call out to userspace for a key if supplementary info was provided - * - cache the key in an appropriate keyring +/** + * request_key_and_link - Request a key and cache it in a keyring. + * @type: The type of key we want. + * @description: The searchable description of the key. + * @callout_info: The data to pass to the instantiation upcall (or NULL). + * @callout_len: The length of callout_info. + * @aux: Auxiliary data for the upcall. + * @dest_keyring: Where to cache the key. + * @flags: Flags to key_alloc(). + * + * A key matching the specified criteria is searched for in the process's + * keyrings and returned with its usage count incremented if found. Otherwise, + * if callout_info is not NULL, a key will be allocated and some service + * (probably in userspace) will be asked to instantiate it. + * + * If successfully found or created, the key will be linked to the destination + * keyring if one is provided. + * + * Returns a pointer to the key if successful; -EACCES, -ENOKEY, -EKEYREVOKED + * or -EKEYEXPIRED if an inaccessible, negative, revoked or expired key was + * found; -ENOKEY if no key was found and no @callout_info was given; -EDQUOT + * if insufficient key quota was available to create a new key; or -ENOMEM if + * insufficient memory was available. + * + * If the returned key was created, then it may still be under construction, + * and wait_for_key_construction() should be used to wait for that to complete. */ struct key *request_key_and_link(struct key_type *type, const char *description, @@ -524,8 +564,16 @@ error: return key; } -/* - * wait for construction of a key to complete +/** + * wait_for_key_construction - Wait for construction of a key to complete + * @key: The key being waited for. + * @intr: Whether to wait interruptibly. + * + * Wait for a key to finish being constructed. + * + * Returns 0 if successful; -ERESTARTSYS if the wait was interrupted; -ENOKEY + * if the key was negated; or -EKEYREVOKED or -EKEYEXPIRED if the key was + * revoked or expired. */ int wait_for_key_construction(struct key *key, bool intr) { @@ -542,12 +590,19 @@ int wait_for_key_construction(struct key *key, bool intr) } EXPORT_SYMBOL(wait_for_key_construction); -/* - * request a key - * - search the process's keyrings - * - check the list of keys being created or updated - * - call out to userspace for a key if supplementary info was provided - * - waits uninterruptible for creation to complete +/** + * request_key - Request a key and wait for construction + * @type: Type of key. + * @description: The searchable description of the key. + * @callout_info: The data to pass to the instantiation upcall (or NULL). + * + * As for request_key_and_link() except that it does not add the returned key + * to a keyring if found, new keys are always allocated in the user's quota, + * the callout_info must be a NUL-terminated string and no auxiliary data can + * be passed. + * + * Furthermore, it then works as wait_for_key_construction() to wait for the + * completion of keys undergoing construction with a non-interruptible wait. */ struct key *request_key(struct key_type *type, const char *description, @@ -572,12 +627,19 @@ struct key *request_key(struct key_type *type, } EXPORT_SYMBOL(request_key); -/* - * request a key with auxiliary data for the upcaller - * - search the process's keyrings - * - check the list of keys being created or updated - * - call out to userspace for a key if supplementary info was provided - * - waits uninterruptible for creation to complete +/** + * request_key_with_auxdata - Request a key with auxiliary data for the upcaller + * @type: The type of key we want. + * @description: The searchable description of the key. + * @callout_info: The data to pass to the instantiation upcall (or NULL). + * @callout_len: The length of callout_info. + * @aux: Auxiliary data for the upcall. + * + * As for request_key_and_link() except that it does not add the returned key + * to a keyring if found and new keys are always allocated in the user's quota. + * + * Furthermore, it then works as wait_for_key_construction() to wait for the + * completion of keys undergoing construction with a non-interruptible wait. */ struct key *request_key_with_auxdata(struct key_type *type, const char *description, @@ -602,10 +664,18 @@ struct key *request_key_with_auxdata(struct key_type *type, EXPORT_SYMBOL(request_key_with_auxdata); /* - * request a key (allow async construction) - * - search the process's keyrings - * - check the list of keys being created or updated - * - call out to userspace for a key if supplementary info was provided + * request_key_async - Request a key (allow async construction) + * @type: Type of key. + * @description: The searchable description of the key. + * @callout_info: The data to pass to the instantiation upcall (or NULL). + * @callout_len: The length of callout_info. + * + * As for request_key_and_link() except that it does not add the returned key + * to a keyring if found, new keys are always allocated in the user's quota and + * no auxiliary data can be passed. + * + * The caller should call wait_for_key_construction() to wait for the + * completion of the returned key if it is still undergoing construction. */ struct key *request_key_async(struct key_type *type, const char *description, @@ -620,9 +690,17 @@ EXPORT_SYMBOL(request_key_async); /* * request a key with auxiliary data for the upcaller (allow async construction) - * - search the process's keyrings - * - check the list of keys being created or updated - * - call out to userspace for a key if supplementary info was provided + * @type: Type of key. + * @description: The searchable description of the key. + * @callout_info: The data to pass to the instantiation upcall (or NULL). + * @callout_len: The length of callout_info. + * @aux: Auxiliary data for the upcall. + * + * As for request_key_and_link() except that it does not add the returned key + * to a keyring if found and new keys are always allocated in the user's quota. + * + * The caller should call wait_for_key_construction() to wait for the + * completion of the returned key if it is still undergoing construction. */ struct key *request_key_async_with_auxdata(struct key_type *type, const char *description, diff --git a/security/keys/request_key_auth.c b/security/keys/request_key_auth.c index ba717b8163ab..68164031a74e 100644 --- a/security/keys/request_key_auth.c +++ b/security/keys/request_key_auth.c @@ -1,4 +1,4 @@ -/* request_key_auth.c: request key authorisation controlling key def +/* Request key authorisation token key definition. * * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) @@ -26,7 +26,7 @@ static void request_key_auth_destroy(struct key *); static long request_key_auth_read(const struct key *, char __user *, size_t); /* - * the request-key authorisation key type definition + * The request-key authorisation key type definition. */ struct key_type key_type_request_key_auth = { .name = ".request_key_auth", @@ -39,7 +39,7 @@ struct key_type key_type_request_key_auth = { }; /* - * instantiate a request-key authorisation key + * Instantiate a request-key authorisation key. */ static int request_key_auth_instantiate(struct key *key, const void *data, @@ -50,7 +50,7 @@ static int request_key_auth_instantiate(struct key *key, } /* - * reading a request-key authorisation key retrieves the callout information + * Describe an authorisation token. */ static void request_key_auth_describe(const struct key *key, struct seq_file *m) @@ -63,7 +63,7 @@ static void request_key_auth_describe(const struct key *key, } /* - * read the callout_info data + * Read the callout_info data (retrieves the callout information). * - the key's semaphore is read-locked */ static long request_key_auth_read(const struct key *key, @@ -89,8 +89,9 @@ static long request_key_auth_read(const struct key *key, } /* - * handle revocation of an authorisation token key - * - called with the key sem write-locked + * Handle revocation of an authorisation token key. + * + * Called with the key sem write-locked. */ static void request_key_auth_revoke(struct key *key) { @@ -105,7 +106,7 @@ static void request_key_auth_revoke(struct key *key) } /* - * destroy an instantiation authorisation token key + * Destroy an instantiation authorisation token key. */ static void request_key_auth_destroy(struct key *key) { @@ -125,8 +126,8 @@ static void request_key_auth_destroy(struct key *key) } /* - * create an authorisation token for /sbin/request-key or whoever to gain - * access to the caller's security data + * Create an authorisation token for /sbin/request-key or whoever to gain + * access to the caller's security data. */ struct key *request_key_auth_new(struct key *target, const void *callout_info, size_t callout_len, struct key *dest_keyring) @@ -220,7 +221,7 @@ error_alloc: } /* - * see if an authorisation key is associated with a particular key + * See if an authorisation key is associated with a particular key. */ static int key_get_instantiation_authkey_match(const struct key *key, const void *_id) @@ -232,11 +233,8 @@ static int key_get_instantiation_authkey_match(const struct key *key, } /* - * get the authorisation key for instantiation of a specific key if attached to - * the current process's keyrings - * - this key is inserted into a keyring and that is set as /sbin/request-key's - * session keyring - * - a target_id of zero specifies any valid token + * Search the current process's keyrings for the authorisation key for + * instantiation of a key. */ struct key *key_get_instantiation_authkey(key_serial_t target_id) { |
