file capabilities: allow sigcont within session
Fix http://bugzilla.kernel.org/show_bug.cgi?id=9247
Allow sigcont to be sent to a process with greater capabilities if it is in
the same session. Otherwise, a shell from which I've started a root shell
and done 'suspend' can't be restarted by the parent shell.
Also don't do file-capabilities signaling checks when uids for the
processes don't match, since the standard check_kill_permission will have
done those checks.
[akpm@linux-foundation.org: coding-style cleanups]
Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Acked-by: Andrew Morgan <morgan@kernel.org>
Cc: Chris Wright <chrisw@sous-sol.org>
Tested-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Stephen Smalley <sds@epoch.ncsc.mil>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: James Morris <jmorris@namei.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/security/commoncap.c b/security/commoncap.c
index bf67871..302e8d0 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -526,6 +526,10 @@
if (info != SEND_SIG_NOINFO && (is_si_special(info) || SI_FROMKERNEL(info)))
return 0;
+ /* sigcont is permitted within same session */
+ if (sig == SIGCONT && (task_session_nr(current) == task_session_nr(p)))
+ return 0;
+
if (secid)
/*
* Signal sent as a particular user.