linux/security/selinux
Ondrej Mosnacek fede148324 selinux: log invalid contexts in AVCs
In case a file has an invalid context set, in an AVC record generated
upon access to such file, the target context is always reported as
unlabeled. This patch adds new optional fields to the AVC record
(srawcon and trawcon) that report the actual context string if it
differs from the one reported in scontext/tcontext. This is useful for
diagnosing SELinux denials involving invalid contexts.

To trigger an AVC that illustrates this situation:

    # setenforce 0
    # touch /tmp/testfile
    # setfattr -n security.selinux -v system_u:object_r:banana_t:s0 /tmp/testfile
    # runcon system_u:system_r:sshd_t:s0 cat /tmp/testfile

AVC before:

type=AVC msg=audit(1547801083.248:11): avc:  denied  { open } for  pid=1149 comm="cat" path="/tmp/testfile" dev="tmpfs" ino=6608 scontext=system_u:system_r:sshd_t:s0 tcontext=system_u:object_r:unlabeled_t:s15:c0.c1023 tclass=file permissive=1

AVC after:

type=AVC msg=audit(1547801083.248:11): avc:  denied  { open } for  pid=1149 comm="cat" path="/tmp/testfile" dev="tmpfs" ino=6608 scontext=system_u:system_r:sshd_t:s0 tcontext=system_u:object_r:unlabeled_t:s15:c0.c1023 tclass=file permissive=1 trawcon=system_u:object_r:banana_t:s0

Note that it is also possible to encounter this situation with the
'scontext' field - e.g. when a new policy is loaded while a process is
running, whose context is not valid in the new policy.

Link: https://bugzilla.redhat.com/show_bug.cgi?id=1135683

Cc: Daniel Walsh <dwalsh@redhat.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2019-01-25 17:31:14 -05:00
..
include selinux: log invalid contexts in AVCs 2019-01-25 17:31:14 -05:00
ss selinux: log invalid contexts in AVCs 2019-01-25 17:31:14 -05:00
.gitignore SELinux: add .gitignore files for dynamic classes 2009-10-24 09:42:27 +08:00
avc.c selinux: log invalid contexts in AVCs 2019-01-25 17:31:14 -05:00
exports.c selinux: sparse fix: include selinux.h in exports.c 2011-09-09 16:56:32 -07:00
hooks.c selinux: do not override context on context mounts 2019-01-10 21:24:43 -05:00
ibpkey.c selinux: wrap global selinux state 2018-03-01 18:48:02 -05:00
Kconfig security: introduce CONFIG_SECURITY_WRITABLE_HOOKS 2017-03-06 11:00:12 +11:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
netif.c selinux: Cleanup printk logging in netif 2018-06-19 13:45:31 -04:00
netlabel.c selinux: wrap AVC state 2018-03-20 16:58:17 -04:00
netlink.c selinux: Cleanup printk logging in netlink 2018-06-19 13:33:05 -04:00
netnode.c selinux: Cleanup printk logging in netnode 2018-06-19 13:49:10 -04:00
netport.c selinux: Cleanup printk logging in netport 2018-06-19 13:43:01 -04:00
nlmsgtab.c selinux: add support for RTM_NEWCHAIN, RTM_DELCHAIN, and RTM_GETCHAIN 2018-11-29 11:32:02 -05:00
selinuxfs.c selinux/stable-4.18 PR 20180814 2018-08-15 10:39:06 -07:00
xfrm.c net: use skb_sec_path helper in more places 2018-12-19 11:21:37 -08:00