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    [PATCH] fix umask when noACL kernel meets extN tuned for ACLs · 2e7842b8
    Hugh Dickins 提交于
    Fix insecure default behaviour reported by Tigran Aivazian: if an ext2 or
    ext3 or ext4 filesystem is tuned to mount with "acl", but mounted by a
    kernel built without ACL support, then umask was ignored when creating
    inodes - though root or user has umask 022, touch creates files as 0666,
    and mkdir creates directories as 0777.
    
    This appears to have worked right until 2.6.11, when a fix to the default
    mode on symlinks (always 0777) assumed VFS applies umask: which it does,
    unless the mount is marked for ACLs; but ext[234] set MS_POSIXACL in
    s_flags according to s_mount_opt set according to def_mount_opts.
    
    We could revert to the 2.6.10 ext[234]_init_acl (adding an S_ISLNK test);
    but other filesystems only set MS_POSIXACL when ACLs are configured.  We
    could fix this at another level; but it seems most robust to avoid setting
    the s_mount_opt flag in the first place (at the expense of more ifdefs).
    
    Likewise don't set the XATTR_USER flag when built without XATTR support.
    Signed-off-by: NHugh Dickins <hugh@veritas.com>
    Cc: Tigran Aivazian <tigran@aivazian.fsnet.co.uk>
    Cc: <linux-ext4@vger.kernel.org>
    Cc: Andreas Gruenbacher <agruen@suse.de>
    Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
    2e7842b8
super.c 78.8 KB