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authorJann Horn <jannh@google.com>2018-09-13 18:12:09 +0200
committerJohn Johansen <john.johansen@canonical.com>2018-09-13 09:44:56 -0700
commit1f8266ff58840d698a1e96d2274189de1bdf7969 (patch)
tree22ec503efa895edcbc8a0bdd465d4206cad19311 /security/apparmor/include
parent5f997580e8b12b9f585e34cc16304925d26ce49e (diff)
downloadlinux-1f8266ff58840d698a1e96d2274189de1bdf7969.tar.gz
apparmor: don't try to replace stale label in ptrace access check
As a comment above begin_current_label_crit_section() explains,
begin_current_label_crit_section() must run in sleepable context because
when label_is_stale() is true, aa_replace_current_label() runs, which uses
prepare_creds(), which can sleep.
Until now, the ptrace access check (which runs with a task lock held)
violated this rule.

Also add a might_sleep() assertion to begin_current_label_crit_section(),
because asserts are less likely to be ignored than comments.

Fixes: b2d09ae449ced ("apparmor: move ptrace checks to using labels")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Diffstat (limited to 'security/apparmor/include')
-rw-r--r--security/apparmor/include/cred.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/security/apparmor/include/cred.h b/security/apparmor/include/cred.h
index e287b7d0d4be..265ae6641a06 100644
--- a/security/apparmor/include/cred.h
+++ b/security/apparmor/include/cred.h
@@ -151,6 +151,8 @@ static inline struct aa_label *begin_current_label_crit_section(void)
 {
 	struct aa_label *label = aa_current_raw_label();
 
+	might_sleep();
+
 	if (label_is_stale(label)) {
 		label = aa_get_newest_label(label);
 		if (aa_replace_current_label(label) == 0)