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authorEric W. Biederman <ebiederm@xmission.com>2017-09-19 01:58:08 +0300
committerEric W. Biederman <ebiederm@xmission.com>2018-05-24 20:02:25 +0300
commitbc6155d1326092f4c29fe05a32b614249620d88e (patch)
treed36853f7e280a4dff8d653981ce71193218c77b7 /fs/namespace.c
parent0031181c49ca94b14b11f08e447f40c6ebc842a4 (diff)
downloadlinux-bc6155d1326092f4c29fe05a32b614249620d88e.tar.xz
fs: Allow superblock owner to access do_remount_sb()
Superblock level remounts are currently restricted to global CAP_SYS_ADMIN, as is the path for changing the root mount to read only on umount. Loosen both of these permission checks to also allow CAP_SYS_ADMIN in any namespace which is privileged towards the userns which originally mounted the filesystem. Signed-off-by: Seth Forshee <seth.forshee@canonical.com> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Acked-by: Serge Hallyn <serge@hallyn.com> Acked-by: Christian Brauner <christian@brauner.io> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Diffstat (limited to 'fs/namespace.c')
-rw-r--r--fs/namespace.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/namespace.c b/fs/namespace.c
index 5f75969adff1..8ddd14806799 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1590,7 +1590,7 @@ static int do_umount(struct mount *mnt, int flags)
* Special case for "unmounting" root ...
* we just try to remount it readonly.
*/
- if (!capable(CAP_SYS_ADMIN))
+ if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN))
return -EPERM;
down_write(&sb->s_umount);
if (!sb_rdonly(sb))
@@ -2333,7 +2333,7 @@ static int do_remount(struct path *path, int ms_flags, int sb_flags,
down_write(&sb->s_umount);
if (ms_flags & MS_BIND)
err = change_mount_flags(path->mnt, ms_flags);
- else if (!capable(CAP_SYS_ADMIN))
+ else if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN))
err = -EPERM;
else
err = do_remount_sb(sb, sb_flags, data, 0);