From 006ebb40d3d65338bd74abb03b945f8d60e362bd Mon Sep 17 00:00:00 2001 From: Stephen Smalley Date: Mon, 19 May 2008 08:32:49 -0400 Subject: Security: split proc ptrace checking into read vs. attach Enable security modules to distinguish reading of process state via proc from full ptrace access by renaming ptrace_may_attach to ptrace_may_access and adding a mode argument indicating whether only read access or full attach access is requested. This allows security modules to permit access to reading process state without granting full ptrace access. The base DAC/capability checking remains unchanged. Read access to /proc/pid/mem continues to apply a full ptrace attach check since check_mem_permission() already requires the current task to already be ptracing the target. The other ptrace checks within proc for elements like environ, maps, and fds are changed to pass the read mode instead of attach. In the SELinux case, we model such reading of process state as a reading of a proc file labeled with the target process' label. This enables SELinux policy to permit such reading of process state without permitting control or manipulation of the target process, as there are a number of cases where programs probe for such information via proc but do not need to be able to control the target (e.g. procps, lsof, PolicyKit, ConsoleKit). At present we have to choose between allowing full ptrace in policy (more permissive than required/desired) or breaking functionality (or in some cases just silencing the denials via dontaudit rules but this can hide genuine attacks). This version of the patch incorporates comments from Casey Schaufler (change/replace existing ptrace_may_attach interface, pass access mode), and Chris Wright (provide greater consistency in the checking). Note that like their predecessors __ptrace_may_attach and ptrace_may_attach, the __ptrace_may_access and ptrace_may_access interfaces use different return value conventions from each other (0 or -errno vs. 1 or 0). I retained this difference to avoid any changes to the caller logic but made the difference clearer by changing the latter interface to return a bool rather than an int and by adding a comment about it to ptrace.h for any future callers. Signed-off-by: Stephen Smalley Acked-by: Chris Wright Signed-off-by: James Morris --- security/smack/smack_lsm.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'security/smack/smack_lsm.c') diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 4a09293efa00..3c7150b3493d 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -95,11 +95,12 @@ struct inode_smack *new_inode_smack(char *smack) * * Do the capability checks, and require read and write. */ -static int smack_ptrace(struct task_struct *ptp, struct task_struct *ctp) +static int smack_ptrace(struct task_struct *ptp, struct task_struct *ctp, + unsigned int mode) { int rc; - rc = cap_ptrace(ptp, ctp); + rc = cap_ptrace(ptp, ctp, mode); if (rc != 0) return rc; -- cgit v1.2.3 From 6f0f0fd496333777d53daff21a4e3b28c4d03a6d Mon Sep 17 00:00:00 2001 From: James Morris Date: Thu, 10 Jul 2008 17:02:07 +0900 Subject: security: remove register_security hook The register security hook is no longer required, as the capability module is always registered. LSMs wishing to stack capability as a secondary module should do so explicitly. Signed-off-by: James Morris Acked-by: Stephen Smalley Acked-by: Greg Kroah-Hartman --- include/linux/security.h | 10 ---------- security/capability.c | 7 ------- security/root_plug.c | 9 --------- security/security.c | 29 ----------------------------- security/selinux/hooks.c | 32 +++++--------------------------- security/smack/smack_lsm.c | 23 ----------------------- 6 files changed, 5 insertions(+), 105 deletions(-) (limited to 'security/smack/smack_lsm.c') diff --git a/include/linux/security.h b/include/linux/security.h index 43c6357568a3..31c8851ec5d0 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -1239,11 +1239,6 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts) * @pages contains the number of pages. * Return 0 if permission is granted. * - * @register_security: - * allow module stacking. - * @name contains the name of the security module being stacked. - * @ops contains a pointer to the struct security_operations of the module to stack. - * * @secid_to_secctx: * Convert secid to security context. * @secid contains the security ID. @@ -1471,10 +1466,6 @@ struct security_operations { int (*netlink_send) (struct sock *sk, struct sk_buff *skb); int (*netlink_recv) (struct sk_buff *skb, int cap); - /* allow module stacking */ - int (*register_security) (const char *name, - struct security_operations *ops); - void (*d_instantiate) (struct dentry *dentry, struct inode *inode); int (*getprocattr) (struct task_struct *p, char *name, char **value); @@ -1564,7 +1555,6 @@ struct security_operations { extern int security_init(void); extern int security_module_enable(struct security_operations *ops); extern int register_security(struct security_operations *ops); -extern int mod_reg_security(const char *name, struct security_operations *ops); extern struct dentry *securityfs_create_file(const char *name, mode_t mode, struct dentry *parent, void *data, const struct file_operations *fops); diff --git a/security/capability.c b/security/capability.c index 6e0671c82018..5b01c0b02422 100644 --- a/security/capability.c +++ b/security/capability.c @@ -721,12 +721,6 @@ static int cap_xfrm_decode_session(struct sk_buff *skb, u32 *fl, int ckall) } #endif /* CONFIG_SECURITY_NETWORK_XFRM */ -static int cap_register_security(const char *name, - struct security_operations *ops) -{ - return -EINVAL; -} - static void cap_d_instantiate(struct dentry *dentry, struct inode *inode) { } @@ -940,7 +934,6 @@ void security_fixup_ops(struct security_operations *ops) set_to_cap_if_null(ops, sem_semop); set_to_cap_if_null(ops, netlink_send); set_to_cap_if_null(ops, netlink_recv); - set_to_cap_if_null(ops, register_security); set_to_cap_if_null(ops, d_instantiate); set_to_cap_if_null(ops, getprocattr); set_to_cap_if_null(ops, setprocattr); diff --git a/security/root_plug.c b/security/root_plug.c index a41cf42a4fa0..be0ebec2580b 100644 --- a/security/root_plug.c +++ b/security/root_plug.c @@ -28,9 +28,6 @@ #include #include -/* flag to keep track of how we were registered */ -static int secondary; - /* default is a generic type of usb to serial converter */ static int vendor_id = 0x0557; static int product_id = 0x2008; @@ -97,13 +94,7 @@ static int __init rootplug_init (void) if (register_security (&rootplug_security_ops)) { printk (KERN_INFO "Failure registering Root Plug module with the kernel\n"); - /* try registering with primary module */ - if (mod_reg_security (MY_NAME, &rootplug_security_ops)) { - printk (KERN_INFO "Failure registering Root Plug " - " module with primary security module.\n"); return -EINVAL; - } - secondary = 1; } printk (KERN_INFO "Root Plug module initialized, " "vendor_id = %4.4x, product id = %4.4x\n", vendor_id, product_id); diff --git a/security/security.c b/security/security.c index 30b0278de394..59f23b5918b3 100644 --- a/security/security.c +++ b/security/security.c @@ -125,35 +125,6 @@ int register_security(struct security_operations *ops) return 0; } -/** - * mod_reg_security - allows security modules to be "stacked" - * @name: a pointer to a string with the name of the security_options to be registered - * @ops: a pointer to the struct security_options that is to be registered - * - * This function allows security modules to be stacked if the currently loaded - * security module allows this to happen. It passes the @name and @ops to the - * register_security function of the currently loaded security module. - * - * The return value depends on the currently loaded security module, with 0 as - * success. - */ -int mod_reg_security(const char *name, struct security_operations *ops) -{ - if (verify(ops)) { - printk(KERN_INFO "%s could not verify " - "security operations.\n", __func__); - return -EINVAL; - } - - if (ops == security_ops) { - printk(KERN_INFO "%s security operations " - "already registered.\n", __func__); - return -EINVAL; - } - - return security_ops->register_security(name, ops); -} - /* Security operations */ int security_ptrace(struct task_struct *parent, struct task_struct *child, diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 745a69e74e38..91200feb3f9c 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -126,13 +126,11 @@ __setup("selinux=", selinux_enabled_setup); int selinux_enabled = 1; #endif -/* Original (dummy) security module. */ -static struct security_operations *original_ops; -/* Minimal support for a secondary security module, - just to allow the use of the dummy or capability modules. - The owlsm module can alternatively be used as a secondary - module as long as CONFIG_OWLSM_FD is not enabled. */ +/* + * Minimal support for a secondary security module, + * just to allow the use of the capability module. + */ static struct security_operations *secondary_ops; /* Lists of inode and superblock security structures initialized @@ -5115,24 +5113,6 @@ static void selinux_ipc_getsecid(struct kern_ipc_perm *ipcp, u32 *secid) *secid = isec->sid; } -/* module stacking operations */ -static int selinux_register_security(const char *name, struct security_operations *ops) -{ - if (secondary_ops != original_ops) { - printk(KERN_ERR "%s: There is already a secondary security " - "module registered.\n", __func__); - return -EINVAL; - } - - secondary_ops = ops; - - printk(KERN_INFO "%s: Registering secondary module %s\n", - __func__, - name); - - return 0; -} - static void selinux_d_instantiate(struct dentry *dentry, struct inode *inode) { if (inode) @@ -5517,8 +5497,6 @@ static struct security_operations selinux_ops = { .sem_semctl = selinux_sem_semctl, .sem_semop = selinux_sem_semop, - .register_security = selinux_register_security, - .d_instantiate = selinux_d_instantiate, .getprocattr = selinux_getprocattr, @@ -5612,7 +5590,7 @@ static __init int selinux_init(void) 0, SLAB_PANIC, NULL); avc_init(); - original_ops = secondary_ops = security_ops; + secondary_ops = security_ops; if (!secondary_ops) panic("SELinux: No initial security operations\n"); if (register_security(&selinux_ops)) diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 3c7150b3493d..ee5a51cbc5eb 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -1822,27 +1822,6 @@ static void smack_ipc_getsecid(struct kern_ipc_perm *ipp, u32 *secid) *secid = smack_to_secid(smack); } -/* module stacking operations */ - -/** - * smack_register_security - stack capability module - * @name: module name - * @ops: module operations - ignored - * - * Allow the capability module to register. - */ -static int smack_register_security(const char *name, - struct security_operations *ops) -{ - if (strcmp(name, "capability") != 0) - return -EINVAL; - - printk(KERN_INFO "%s: Registering secondary module %s\n", - __func__, name); - - return 0; -} - /** * smack_d_instantiate - Make sure the blob is correct on an inode * @opt_dentry: unused @@ -2673,8 +2652,6 @@ struct security_operations smack_ops = { .netlink_send = cap_netlink_send, .netlink_recv = cap_netlink_recv, - .register_security = smack_register_security, - .d_instantiate = smack_d_instantiate, .getprocattr = smack_getprocattr, -- cgit v1.2.3