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| author | Rafal Krypa <r.krypa@samsung.com> | 2016-04-04 11:14:53 +0200 |
|---|---|---|
| committer | Casey Schaufler <casey@schaufler-ca.com> | 2016-06-08 13:52:31 -0700 |
| commit | 18d872f77cecec2677a394170f26aaeb08562cee (patch) | |
| tree | b9d58ab693ce181382a7c62a4d8a42676248a3fe | |
| parent | 40d273782ff16fe1a7445cc05c66a447dfea3433 (diff) | |
| download | linux-0-day-18d872f77cecec2677a394170f26aaeb08562cee.tar.gz linux-0-day-18d872f77cecec2677a394170f26aaeb08562cee.tar.xz | |
Smack: ignore null signal in smack_task_kill
Kill with signal number 0 is commonly used for checking PID existence.
Smack treated such cases like any other kills, although no signal is
actually delivered when sig == 0.
Checking permissions when sig == 0 didn't prevent an unprivileged caller
from learning whether PID exists or not. When it existed, kernel returned
EPERM, when it didn't - ESRCH. The only effect of policy check in such
case is noise in audit logs.
This change lets Smack silently ignore kill() invocations with sig == 0.
Signed-off-by: Rafal Krypa <r.krypa@samsung.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
| -rw-r--r-- | security/smack/smack_lsm.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 6777295f4b2b7..e96080eaacbbb 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -2227,6 +2227,9 @@ static int smack_task_kill(struct task_struct *p, struct siginfo *info, struct smack_known *tkp = smk_of_task_struct(p); int rc; + if (!sig) + return 0; /* null signal; existence test */ + smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_TASK); smk_ad_setfield_u_tsk(&ad, p); /* |