From 12b29f34558b9b45a2c6eabd4f3c6be939a3980f Mon Sep 17 00:00:00 2001 From: Stephen Smalley Date: Wed, 7 May 2008 13:03:20 -0400 Subject: selinux: support deferred mapping of contexts Introduce SELinux support for deferred mapping of security contexts in the SID table upon policy reload, and use this support for inode security contexts when the context is not yet valid under the current policy. Only processes with CAP_MAC_ADMIN + mac_admin permission in policy can set undefined security contexts on inodes. Inodes with such undefined contexts are treated as having the unlabeled context until the context becomes valid upon a policy reload that defines the context. Context invalidation upon policy reload also uses this support to save the context information in the SID table and later recover it upon a subsequent policy reload that defines the context again. This support is to enable package managers and similar programs to set down file contexts unknown to the system policy at the time the file is created in order to better support placing loadable policy modules in packages and to support build systems that need to create images of different distro releases with different policies w/o requiring all of the contexts to be defined or legal in the build host policy. With this patch applied, the following sequence is possible, although in practice it is recommended that this permission only be allowed to specific program domains such as the package manager. # rmdir baz # rm bar # touch bar # chcon -t foo_exec_t bar # foo_exec_t is not yet defined chcon: failed to change context of `bar' to `system_u:object_r:foo_exec_t': Invalid argument # mkdir -Z system_u:object_r:foo_exec_t baz mkdir: failed to set default file creation context to `system_u:object_r:foo_exec_t': Invalid argument # cat setundefined.te policy_module(setundefined, 1.0) require { type unconfined_t; type unlabeled_t; } files_type(unlabeled_t) allow unconfined_t self:capability2 mac_admin; # make -f /usr/share/selinux/devel/Makefile setundefined.pp # semodule -i setundefined.pp # chcon -t foo_exec_t bar # foo_exec_t is not yet defined # mkdir -Z system_u:object_r:foo_exec_t baz # ls -Zd bar baz -rw-r--r-- root root system_u:object_r:unlabeled_t bar drwxr-xr-x root root system_u:object_r:unlabeled_t baz # cat foo.te policy_module(foo, 1.0) type foo_exec_t; files_type(foo_exec_t) # make -f /usr/share/selinux/devel/Makefile foo.pp # semodule -i foo.pp # defines foo_exec_t # ls -Zd bar baz -rw-r--r-- root root user_u:object_r:foo_exec_t bar drwxr-xr-x root root system_u:object_r:foo_exec_t baz # semodule -r foo # ls -Zd bar baz -rw-r--r-- root root system_u:object_r:unlabeled_t bar drwxr-xr-x root root system_u:object_r:unlabeled_t baz # semodule -i foo.pp # ls -Zd bar baz -rw-r--r-- root root user_u:object_r:foo_exec_t bar drwxr-xr-x root root system_u:object_r:foo_exec_t baz # semodule -r setundefined foo # chcon -t foo_exec_t bar # no longer defined and not allowed chcon: failed to change context of `bar' to `system_u:object_r:foo_exec_t': Invalid argument # rmdir baz # mkdir -Z system_u:object_r:foo_exec_t baz mkdir: failed to set default file creation context to `system_u:object_r:foo_exec_t': Invalid argument Signed-off-by: Stephen Smalley Signed-off-by: James Morris --- security/selinux/ss/sidtab.c | 58 +++++++++++++++----------------------------- 1 file changed, 19 insertions(+), 39 deletions(-) (limited to 'security/selinux/ss/sidtab.c') diff --git a/security/selinux/ss/sidtab.c b/security/selinux/ss/sidtab.c index 4a516ff4bcde..ba3541640491 100644 --- a/security/selinux/ss/sidtab.c +++ b/security/selinux/ss/sidtab.c @@ -86,7 +86,7 @@ out: return rc; } -struct context *sidtab_search(struct sidtab *s, u32 sid) +static struct context *sidtab_search_core(struct sidtab *s, u32 sid, int force) { int hvalue; struct sidtab_node *cur; @@ -99,7 +99,10 @@ struct context *sidtab_search(struct sidtab *s, u32 sid) while (cur != NULL && sid > cur->sid) cur = cur->next; - if (cur == NULL || sid != cur->sid) { + if (force && cur && sid == cur->sid && cur->context.len) + return &cur->context; + + if (cur == NULL || sid != cur->sid || cur->context.len) { /* Remap invalid SIDs to the unlabeled SID. */ sid = SECINITSID_UNLABELED; hvalue = SIDTAB_HASH(sid); @@ -113,6 +116,16 @@ struct context *sidtab_search(struct sidtab *s, u32 sid) return &cur->context; } +struct context *sidtab_search(struct sidtab *s, u32 sid) +{ + return sidtab_search_core(s, sid, 0); +} + +struct context *sidtab_search_force(struct sidtab *s, u32 sid) +{ + return sidtab_search_core(s, sid, 1); +} + int sidtab_map(struct sidtab *s, int (*apply) (u32 sid, struct context *context, @@ -138,43 +151,6 @@ out: return rc; } -void sidtab_map_remove_on_error(struct sidtab *s, - int (*apply) (u32 sid, - struct context *context, - void *args), - void *args) -{ - int i, ret; - struct sidtab_node *last, *cur, *temp; - - if (!s) - return; - - for (i = 0; i < SIDTAB_SIZE; i++) { - last = NULL; - cur = s->htable[i]; - while (cur != NULL) { - ret = apply(cur->sid, &cur->context, args); - if (ret) { - if (last) - last->next = cur->next; - else - s->htable[i] = cur->next; - temp = cur; - cur = cur->next; - context_destroy(&temp->context); - kfree(temp); - s->nel--; - } else { - last = cur; - cur = cur->next; - } - } - } - - return; -} - static inline u32 sidtab_search_context(struct sidtab *s, struct context *context) { @@ -215,6 +191,10 @@ int sidtab_context_to_sid(struct sidtab *s, goto unlock_out; } sid = s->next_sid++; + if (context->len) + printk(KERN_INFO + "SELinux: Context %s is not valid (left unmapped).\n", + context->str); ret = sidtab_insert(s, sid, context); if (ret) s->next_sid--; -- cgit v1.2.3 From bdd581c1439339f1d3e8446b83e0f1beaef294e9 Mon Sep 17 00:00:00 2001 From: James Morris Date: Fri, 6 Jun 2008 18:50:12 +1000 Subject: SELinux: open code sidtab lock Open code sidtab lock to make Andrew Morton happy. Signed-off-by: James Morris Acked-by: Stephen Smalley --- security/selinux/ss/sidtab.c | 18 +++++++----------- 1 file changed, 7 insertions(+), 11 deletions(-) (limited to 'security/selinux/ss/sidtab.c') diff --git a/security/selinux/ss/sidtab.c b/security/selinux/ss/sidtab.c index ba3541640491..a81ded104129 100644 --- a/security/selinux/ss/sidtab.c +++ b/security/selinux/ss/sidtab.c @@ -14,10 +14,6 @@ #define SIDTAB_HASH(sid) \ (sid & SIDTAB_HASH_MASK) -#define INIT_SIDTAB_LOCK(s) spin_lock_init(&s->lock) -#define SIDTAB_LOCK(s, x) spin_lock_irqsave(&s->lock, x) -#define SIDTAB_UNLOCK(s, x) spin_unlock_irqrestore(&s->lock, x) - int sidtab_init(struct sidtab *s) { int i; @@ -30,7 +26,7 @@ int sidtab_init(struct sidtab *s) s->nel = 0; s->next_sid = 1; s->shutdown = 0; - INIT_SIDTAB_LOCK(s); + spin_lock_init(&s->lock); return 0; } @@ -180,7 +176,7 @@ int sidtab_context_to_sid(struct sidtab *s, sid = sidtab_search_context(s, context); if (!sid) { - SIDTAB_LOCK(s, flags); + spin_lock_irqsave(&s->lock, flags); /* Rescan now that we hold the lock. */ sid = sidtab_search_context(s, context); if (sid) @@ -199,7 +195,7 @@ int sidtab_context_to_sid(struct sidtab *s, if (ret) s->next_sid--; unlock_out: - SIDTAB_UNLOCK(s, flags); + spin_unlock_irqrestore(&s->lock, flags); } if (ret) @@ -264,19 +260,19 @@ void sidtab_set(struct sidtab *dst, struct sidtab *src) { unsigned long flags; - SIDTAB_LOCK(src, flags); + spin_lock_irqsave(&src->lock, flags); dst->htable = src->htable; dst->nel = src->nel; dst->next_sid = src->next_sid; dst->shutdown = 0; - SIDTAB_UNLOCK(src, flags); + spin_unlock_irqrestore(&src->lock, flags); } void sidtab_shutdown(struct sidtab *s) { unsigned long flags; - SIDTAB_LOCK(s, flags); + spin_lock_irqsave(&s->lock, flags); s->shutdown = 1; - SIDTAB_UNLOCK(s, flags); + spin_unlock_irqrestore(&s->lock, flags); } -- cgit v1.2.3