[PATCH RESEND v2 13/18] fs: Allow superblock owner to access do_remount_sb()
From: Seth Forshee <hidden>
Date: 2016-01-04 18:04:40
Also in:
dm-devel, linux-bcache, linux-fsdevel, lkml, selinux
Subsystem:
filesystems (vfs and infrastructure), the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
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 <redacted> Acked-by: "Eric W. Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> Acked-by: Serge Hallyn <redacted> --- fs/namespace.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/namespace.c b/fs/namespace.c
index 18fc58760aec..b00a765895e7 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c@@ -1510,7 +1510,7 @@ 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->s_flags & MS_RDONLY))
@@ -2199,7 +2199,7 @@ static int do_remount(struct path *path, int flags, int mnt_flags, down_write(&sb->s_umount); if (flags & MS_BIND) err = change_mount_flags(path->mnt, 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, flags, data, 0);
--
1.9.1
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