perf: Disable monitoring on setuid processes for regular users

There was a a bug in setup_new_exec(), whereby the test to disabled perf monitoring was not correct because the new credentials for the process were not yet committed and therefore the get_dumpable() test was never firing. The patch fixes the problem by moving the perf_event test until after the credentials are committed. Signed-off-by: Stephane Eranian <[email protected]> Tested-by: Jiri Olsa <[email protected]> Acked-by: Peter Zijlstra <[email protected]> Cc: <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
kishon · Jun 26, 2013 · 2976b10 · 2976b10
1 parent c790b0a
commit 2976b10
Showing 1 changed file with 9 additions and 7 deletions.
diff --git a/fs/exec.c b/fs/exec.c
@@ -1135,13 +1135,6 @@ void setup_new_exec(struct linux_binprm * bprm)
 			set_dumpable(current->mm, suid_dumpable);
 	}
 
-	/*
-	 * Flush performance counters when crossing a
-	 * security domain:
-	 */
-	if (!get_dumpable(current->mm))
-		perf_event_exit_task(current);
-
 	/* An exec changes our domain. We are no longer part of the thread
 	   group */
 
@@ -1205,6 +1198,15 @@ void install_exec_creds(struct linux_binprm *bprm)
 
 	commit_creds(bprm->cred);
 	bprm->cred = NULL;
+
+	/*
+	 * Disable monitoring for regular users
+	 * when executing setuid binaries. Must
+	 * wait until new credentials are committed
+	 * by commit_creds() above
+	 */
+	if (get_dumpable(current->mm) != SUID_DUMP_USER)
+		perf_event_exit_task(current);
 	/*
 	 * cred_guard_mutex must be held at least to this point to prevent
 	 * ptrace_attach() from altering our determination of the task's