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authorEric Paris <eparis@redhat.com>2010-07-23 11:44:03 -0400
committerJames Morris <jmorris@namei.org>2010-08-02 15:35:07 +1000
commitb782e0a68d17894d9a618ffea55b33639faa6bb4 (patch)
tree307bc615153075a6e92be5d839a58ff48d6525f3 /include/linux/lsm_audit.h
parentd09ca73979460b96d5d4684d588b188be9a1f57d (diff)
SELinux: special dontaudit for access checks
Currently there are a number of applications (nautilus being the main one) which calls access() on files in order to determine how they should be displayed. It is normal and expected that nautilus will want to see if files are executable or if they are really read/write-able. access() should return the real permission. SELinux policy checks are done in access() and can result in lots of AVC denials as policy denies RWX on files which DAC allows. Currently SELinux must dontaudit actual attempts to read/write/execute a file in order to silence these messages (and not flood the logs.) But dontaudit rules like that can hide real attacks. This patch addes a new common file permission audit_access. This permission is special in that it is meaningless and should never show up in an allow rule. Instead the only place this permission has meaning is in a dontaudit rule like so: dontaudit nautilus_t sbin_t:file audit_access With such a rule if nautilus just checks access() we will still get denied and thus userspace will still get the correct answer but we will not log the denial. If nautilus attempted to actually perform one of the forbidden actions (rather than just querying access(2) about it) we would still log a denial. This type of dontaudit rule should be used sparingly, as it could be a method for an attacker to probe the system permissions without detection. Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: Stephen D. Smalley <sds@tycho.nsa.gov> Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'include/linux/lsm_audit.h')
-rw-r--r--include/linux/lsm_audit.h5
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/lsm_audit.h b/include/linux/lsm_audit.h
index 6907251d5200..788f0ab937aa 100644
--- a/include/linux/lsm_audit.h
+++ b/include/linux/lsm_audit.h
@@ -90,6 +90,11 @@ struct common_audit_data {
u32 requested;
u32 audited;
u32 denied;
+ /*
+ * auditdeny is a bit tricky and unintuitive. See the
+ * comments in avc.c for it's meaning and usage.
+ */
+ u32 auditdeny;
struct av_decision *avd;
int result;
} selinux_audit_data;

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