diff options
| author | Eric W. Biederman <ebiederm@xmission.com> | 2014-12-06 01:14:19 +0100 |
|---|---|---|
| committer | Eric W. Biederman <ebiederm@xmission.com> | 2014-12-10 00:08:24 +0100 |
| commit | be7c6dba2332cef0677fbabb606e279ae76652c3 (patch) | |
| tree | 52d7a02dc25a3c2ac64576a9288114d0741cc846 | |
| parent | userns: Don't allow setgroups until a gid mapping has been setablished (diff) | |
| download | linux-be7c6dba2332cef0677fbabb606e279ae76652c3.tar.xz linux-be7c6dba2332cef0677fbabb606e279ae76652c3.zip | |
userns: Don't allow unprivileged creation of gid mappings
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.
Cc: stable@vger.kernel.org
Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
| -rw-r--r-- | kernel/user_namespace.c | 4 |
1 files changed, 0 insertions, 4 deletions
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index 27c8dab48c07..1ce6d67c07b7 100644 --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -821,10 +821,6 @@ static bool new_idmap_permitted(const struct file *file, kuid_t uid = make_kuid(ns->parent, id); 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; } } |