linux.git/fs/ext2/acl.c, branch v4.8

posix_acl: Inode acl caching fixes

2016-03-31T04:30:15+00:00

When get_acl() is called for an inode whose ACL is not cached yet, the
get_acl inode operation is called to fetch the ACL from the filesystem.
The inode operation is responsible for updating the cached acl with
set_cached_acl().  This is done without locking at the VFS level, so
another task can call set_cached_acl() or forget_cached_acl() before the
get_acl inode operation gets to calling set_cached_acl(), and then
get_acl's call to set_cached_acl() results in caching an outdate ACL.

Prevent this from happening by setting the cached ACL pointer to a
task-specific sentinel value before calling the get_acl inode operation.
Move the responsibility for updating the cached ACL from the get_acl
inode operations to get_acl().  There, only set the cached ACL if the
sentinel value hasn't changed.

The sentinel values are chosen to have odd values.  Likewise, the value
of ACL_NOT_CACHED is odd.  In contrast, ACL object pointers always have
an even value (ACLs are aligned in memory).  This allows to distinguish
uncached ACLs values from ACL objects.

In addition, switch from guarding inode->i_acl and inode->i_default_acl
upates by the inode->i_lock spinlock to using xchg() and cmpxchg().

Filesystems that do not want ACLs returned from their get_acl inode
operations to be cached must call forget_cached_acl() to prevent the VFS
from doing so.

(Patch written by Al Viro and Andreas Gruenbacher.)

Signed-off-by: Andreas Gruenbacher 
Signed-off-by: Al Viro

ext2: acl: remove unneeded include of linux/capability.h

2014-04-01T21:36:43+00:00

acl.c has not been (directly) using the interface defined by
linux/capability.h header since commit 3bd858ab1c451725c07a
("Introduce is_owner_or_cap() to wrap CAP_FOWNER use with fsuid
check"). Remove it.

Signed-off-by: Jakub Sitnicki 
Signed-off-by: Jan Kara

ext2/3/4: use generic posix ACL infrastructure

2014-01-26T04:58:19+00:00

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jan Kara 
Signed-off-by: Al Viro

fs: make posix_acl_create more useful

2014-01-26T04:58:18+00:00

Rename the current posix_acl_created to __posix_acl_create and add
a fully featured helper to set up the ACLs on file creation that
uses get_acl().

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jan Kara 
Signed-off-by: Al Viro

fs: make posix_acl_chmod more useful

2014-01-26T04:58:18+00:00

Rename the current posix_acl_chmod to __posix_acl_chmod and add
a fully featured ACL chmod helper that uses the ->set_acl inode
operation.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Jan Kara 
Signed-off-by: Al Viro

userns: Convert extN to support kuids and kgids in posix acls

2012-09-18T08:01:36+00:00

Convert ext2, ext3, and ext4 to fully support the posix acl changes,
using e_uid e_gid instead e_id.

Enabled building with posix acls enabled, all filesystems supporting
user namespaces, now also support posix acls when user namespaces are enabled.

Cc: Theodore Tso 
Cc: Andrew Morton 
Cc: Andreas Dilger 
Cc: Jan Kara 
Cc: Al Viro 
Signed-off-by: Eric W. Biederman

userns: Pass a userns parameter into posix_acl_to_xattr and posix_acl_from_xattr

2012-09-18T08:01:35+00:00

 - Pass the user namespace the uid and gid values in the xattr are stored
   in into posix_acl_from_xattr.

 - Pass the user namespace kuid and kgid values should be converted into
   when storing uid and gid values in an xattr in posix_acl_to_xattr.

- Modify all callers of posix_acl_from_xattr and posix_acl_to_xattr to
  pass in &init_user_ns.

In the short term this change is not strictly needed but it makes the
code clearer.  In the longer term this change is necessary to be able to
mount filesystems outside of the initial user namespace that natively
store posix acls in the linux xattr format.

Cc: Theodore Tso 
Cc: Andrew Morton 
Cc: Andreas Dilger 
Cc: Jan Kara 
Cc: Al Viro 
Signed-off-by: "Eric W. Biederman"

switch posix_acl_equiv_mode() to umode_t *

2011-08-01T06:10:06+00:00

... so that &inode->i_mode could be passed to it

Signed-off-by: Al Viro

switch posix_acl_create() to umode_t *

2011-08-01T06:09:42+00:00

so we can pass &inode->i_mode to it

Signed-off-by: Al Viro

fs: take the ACL checks to common code

2011-07-25T18:30:23+00:00

Replace the ->check_acl method with a ->get_acl method that simply reads an
ACL from disk after having a cache miss.  This means we can replace the ACL
checking boilerplate code with a single implementation in namei.c.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Al Viro