From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
commit be7c6dba2332cef0677fbabb606e279ae76652c3 upstream.
As any gid mapping will allow and must allow for backwards
compatibility dropping groups don't allow any gid mappings to be
established without CAP_SETGID in the parent user namespace.
For a small class of applications this change breaks userspace
and removes useful functionality. This small class of applications
includes tools/testing/selftests/mount/unprivilged-remount-test.c
Most of the removed functionality will be added back with the addition
of a one way knob to disable setgroups. Once setgroups is disabled
setting the gid_map becomes as safe as setting the uid_map.
For more common applications that set the uid_map and the gid_map
with privilege this change will have no affect.
This is part of a fix for CVE-2014-8989.
Reviewed-by: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
kernel/user_namespace.c | 5 -----
1 file changed, 5 deletions(-)
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 048bb7b641a9..a5809c42a1b3 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -808,11 +808,6 @@ static bool new_idmap_permitted(const struct file *file,
if (uid_eq(uid, file->f_cred->fsuid))
return true;
}
- else if (cap_setid == CAP_SETGID) {
- kgid_t gid = make_kgid(ns->parent, id);
- if (gid_eq(gid, file->f_cred->fsgid))
- return true;
- }
}
/* Allow anyone to set a mapping that doesn't require privilege */
--
2.2.1
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