When ns->level is not larger then cred->user_ns->level,
then ns can't be cred->user_ns's descendant, and
there is no a sence to search in parents.
So, breake the cycle earlier and skip needless iterations.
v2: Change comment on suggested by Andy Lutomirski.
Signed-off-by: Kirill Tkhai <ktk...@virtuozzo.com>
---
security/commoncap.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/security/commoncap.c b/security/commoncap.c
index 78b37838a2d3..a424aa0123af 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -82,8 +82,11 @@ int cap_capable(const struct cred *cred, struct
user_namespace *targ_ns,
if (ns == cred->user_ns)
return cap_raised(cred->cap_effective, cap) ? 0 :
-EPERM;
- /* Have we tried all of the parent namespaces? */
- if (ns == &init_user_ns)
+ /*
+ * If we're already at a lower level than we're looking for,
we're
+ * done searching.
+ */
+ if (ns->level <= cred->user_ns->level)
return -EPERM;
/*
