Linux-Fsdevel Archive on lore.kernel.org
help / color / mirror / Atom feed
* [PATCH 1/2] linux/fs.h: fix umask on NFS with CONFIG_FS_POSIX_ACL=n
@ 2018-01-15 17:30 Max Kellermann
  2018-01-15 17:30 ` [PATCH 2/2] dFrom: Max Kellermann <mk@cm4all.com> Max Kellermann
  2018-01-17 16:37 ` [PATCH 1/2] linux/fs.h: fix umask on NFS with CONFIG_FS_POSIX_ACL=n J. Bruce Fields
  0 siblings, 2 replies; 6+ messages in thread
From: Max Kellermann @ 2018-01-15 17:30 UTC (permalink / raw)
  To: linux-fsdevel, hch, linux-nfs, trond.myklebust, gregkh
  Cc: max.kellermann, linux-kernel

Make IS_POSIXACL() return false if POSIX ACL support is disabled and
ignore SB_POSIXACL/MS_POSIXACL.

Never skip applying the umask in namei.c and never bother to do any
ACL specific checks if the filesystem falsely indicates it has ACLs
enabled when the feature is completely disabled in the kernel.

This fixes a problem where the umask is always ignored in the NFS
client when compiled without CONFIG_FS_POSIX_ACL.  This is a 4 year
old regression caused by commit 013cdf1088d723 which itself was not
completely wrong, but failed to consider all the side effects by
misdesigned VFS code.

Prior to that commit, there were two places where the umask could be
applied, for example when creating a directory:

 1. in the VFS layer in SYSCALL_DEFINE3(mkdirat), but only if
    !IS_POSIXACL()

 2. again (unconditionally) in nfs3_proc_mkdir()

The first one does not apply, because even without
CONFIG_FS_POSIX_ACL, the NFS client sets MS_POSIXACL in
nfs_fill_super().

After that commit, (2.) was replaced by:

 2b. in posix_acl_create(), called by nfs3_proc_mkdir()

There's one branch in posix_acl_create() which applies the umask;
however, without CONFIG_FS_POSIX_ACL, posix_acl_create() is an empty
dummy function which does not apply the umask.

The approach chosen by this patch is to make IS_POSIXACL() always
return false when POSIX ACL support is disabled, so the umask always
gets applied by the VFS layer.  This is consistent with the (regular)
behavior of posix_acl_create(): that function returns early if
IS_POSIXACL() is false, before applying the umask.

Therefore, posix_acl_create() is responsible for applying the umask if
there is ACL support enabled in the file system (SB_POSIXACL), and the
VFS layer is responsible for all other cases (no SB_POSIXACL or no
CONFIG_FS_POSIX_ACL).

Signed-off-by: Max Kellermann <mk@cm4all.com>
---
 include/linux/fs.h |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 440281f8564d..c3240c28e61b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1883,7 +1883,12 @@ static inline bool sb_rdonly(const struct super_block *sb) { return sb->s_flags
 #define IS_NOQUOTA(inode)	((inode)->i_flags & S_NOQUOTA)
 #define IS_APPEND(inode)	((inode)->i_flags & S_APPEND)
 #define IS_IMMUTABLE(inode)	((inode)->i_flags & S_IMMUTABLE)
+
+#ifdef CONFIG_FS_POSIX_ACL
 #define IS_POSIXACL(inode)	__IS_FLG(inode, SB_POSIXACL)
+#else
+#define IS_POSIXACL(inode)	0
+#endif
 
 #define IS_DEADDIR(inode)	((inode)->i_flags & S_DEAD)
 #define IS_NOCMTIME(inode)	((inode)->i_flags & S_NOCMTIME)

^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2018-01-17 16:37 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-01-15 17:30 [PATCH 1/2] linux/fs.h: fix umask on NFS with CONFIG_FS_POSIX_ACL=n Max Kellermann
2018-01-15 17:30 ` [PATCH 2/2] dFrom: Max Kellermann <mk@cm4all.com> Max Kellermann
2018-01-15 17:41   ` Greg KH
2018-01-15 17:43     ` Max Kellermann
2018-01-16 15:06   ` Trond Myklebust
2018-01-17 16:37 ` [PATCH 1/2] linux/fs.h: fix umask on NFS with CONFIG_FS_POSIX_ACL=n J. Bruce Fields

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).