fs: Allow CAP_SYS_ADMIN in s_user_ns to freeze and thaw filesystems

The user in control of a super block should be allowed to freeze
and thaw it. Relax the restrictions on the FIFREEZE and FITHAW
ioctls to require CAP_SYS_ADMIN in s_user_ns.

Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: Christian Brauner <christian@brauner.io>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

diff --git a/fs/ioctl.c b/fs/ioctl.c
index 4823431..b445b13 100644 (file)
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -549,7 +549,7 @@ static int ioctl_fsfreeze(struct file *filp)
 {
        struct super_block *sb = file_inode(filp)->i_sb;
 
-       if (!capable(CAP_SYS_ADMIN))
+       if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN))
                return -EPERM;
 
        /* If filesystem doesn't support freeze feature, return. */
@@ -566,7 +566,7 @@ static int ioctl_fsthaw(struct file *filp)
 {
        struct super_block *sb = file_inode(filp)->i_sb;
 
-       if (!capable(CAP_SYS_ADMIN))
+       if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN))
                return -EPERM;
 
        /* Thaw */