linux/security
Eric Paris b782e0a68d 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>
2010-08-02 15:35:07 +10:00
..
integrity/ima ima: use generic_file_llseek for securityfs 2010-08-02 15:34:58 +10:00
keys KEYS: Reinstate lost passing of process keyring ID in call_sbin_request_key() 2010-08-02 15:34:56 +10:00
selinux SELinux: special dontaudit for access checks 2010-08-02 15:35:07 +10:00
smack security: make LSMs explicitly mask off permissions 2010-08-02 15:35:07 +10:00
tomoyo TOMOYO: Explicitly set file_operations->llseek pointer. 2010-08-02 15:34:57 +10:00
capability.c Security: capability: code style issue 2010-08-02 15:35:00 +10:00
commoncap.c security: whitespace coding style fixes 2010-04-23 10:10:23 +10:00
device_cgroup.c Merge branch 'master' into next 2010-05-06 10:56:07 +10:00
inode.c securityfs: Drop dentry reference count when mknod fails 2010-08-02 15:34:59 +10:00
Kconfig remove CONFIG_SECURITY_FILE_CAPABILITIES compile option 2009-11-24 15:06:47 +11:00
lsm_audit.c Merge branch 'master' into next 2010-05-06 10:56:07 +10:00
Makefile NOMMU: Optimise away the {dac_,}mmap_min_addr tests 2009-12-17 09:25:19 +11:00
min_addr.c mmap_min_addr check CAP_SYS_RAWIO only for write 2010-04-23 08:56:31 +10:00
security.c LSM: Remove unused arguments from security_path_truncate(). 2010-08-02 15:33:40 +10:00