Eric Lee / smarc-ti-linux-kernel

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Commit 804733ad85b1ab68812fa438b3b4133d1d85581a

Authored by Eric W. Biederman
Committed by Greg Kroah-Hartman
1 parent f077e88fc9
Exists in smarc-ti-linux-3.14.y and in 1 other branch processor-sdk-linux-01.00.00

userns: Don't allow unprivileged creation of gid mappings 

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@amacapital.net>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Showing 1 changed file with 0 additions and 5 deletions Side-by-side Diff

kernel/user_namespace.c
Diff comments   View file @ 804733a
... ... @@ -814,11 +814,6 @@
814 814 if (uid_eq(uid, file->f_cred->fsuid))
815 815 return true;
816 816 }
817   - else if (cap_setid == CAP_SETGID) {
818   - kgid_t gid = make_kgid(ns->parent, id);
819   - if (gid_eq(gid, file->f_cred->fsgid))
820   - return true;
821   - }
822 817 }
823 818  
824 819 /* Allow anyone to set a mapping that doesn't require privilege */