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author | Alistair Delva <adelva@google.com> | 2021-11-15 21:16:55 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-11-26 12:39:19 +0300 |
commit | cc73242889b5d24a7449bb1f8ca46d2768c3496f (patch) | |
tree | ad94c465c564367fca668a3e2c036f9b52b3ffa3 | |
parent | 63e2f34abc22004011fa6bf8b402681dae103b2a (diff) | |
download | linux-cc73242889b5d24a7449bb1f8ca46d2768c3496f.tar.xz |
block: Check ADMIN before NICE for IOPRIO_CLASS_RT
commit 94c4b4fd25e6c3763941bdec3ad54f2204afa992 upstream.
Booting to Android userspace on 5.14 or newer triggers the following
SELinux denial:
avc: denied { sys_nice } for comm="init" capability=23
scontext=u:r:init:s0 tcontext=u:r:init:s0 tclass=capability
permissive=0
Init is PID 0 running as root, so it already has CAP_SYS_ADMIN. For
better compatibility with older SEPolicy, check ADMIN before NICE.
Fixes: 9d3a39a5f1e4 ("block: grant IOPRIO_CLASS_RT to CAP_SYS_NICE")
Signed-off-by: Alistair Delva <adelva@google.com>
Cc: Khazhismel Kumykov <khazhy@google.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Paul Moore <paul@paul-moore.com>
Cc: selinux@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: kernel-team@android.com
Cc: stable@vger.kernel.org # v5.14+
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Serge Hallyn <serge@hallyn.com>
Link: https://lore.kernel.org/r/20211115181655.3608659-1-adelva@google.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | block/ioprio.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/block/ioprio.c b/block/ioprio.c index 364d2294ba90..84da6c71b2cc 100644 --- a/block/ioprio.c +++ b/block/ioprio.c @@ -69,7 +69,14 @@ int ioprio_check_cap(int ioprio) switch (class) { case IOPRIO_CLASS_RT: - if (!capable(CAP_SYS_NICE) && !capable(CAP_SYS_ADMIN)) + /* + * Originally this only checked for CAP_SYS_ADMIN, + * which was implicitly allowed for pid 0 by security + * modules such as SELinux. Make sure we check + * CAP_SYS_ADMIN first to avoid a denial/avc for + * possibly missing CAP_SYS_NICE permission. + */ + if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_NICE)) return -EPERM; fallthrough; /* rt has prio field too */ |