linux-stable.git/fs/xattr.c, branch linux-3.2.y

lsm: fix smack_inode_removexattr and xattr_getsecurity memleak

2018-01-01T20:50:56+00:00

commit 57e7ba04d422c3d41c8426380303ec9b7533ded9 upstream.

security_inode_getsecurity() provides the text string value
of a security attribute. It does not provide a "secctx".
The code in xattr_getsecurity() that calls security_inode_getsecurity()
and then calls security_release_secctx() happened to work because
SElinux and Smack treat the attribute and the secctx the same way.
It fails for cap_inode_getsecurity(), because that module has no
secctx that ever needs releasing. It turns out that Smack is the
one that's doing things wrong by not allocating memory when instructed
to do so by the "alloc" parameter.

The fix is simple enough. Change the security_release_secctx() to
kfree() because it isn't a secctx being returned by
security_inode_getsecurity(). Change Smack to allocate the string when
told to do so.

Note: this also fixes memory leaks for LSMs which implement
inode_getsecurity but not release_secctx, such as capabilities.

Signed-off-by: Casey Schaufler 
Reported-by: Konstantin Khlebnikov 
Signed-off-by: James Morris 
[bwh: Backported to 3.2:
 - s/isp->smk_known/isp/
 - Adjust context]
Signed-off-by: Ben Hutchings

evm: evm_inode_post_removexattr

2011-07-18T16:29:43+00:00

When an EVM protected extended attribute is removed, update 'security.evm'.

Signed-off-by: Mimi Zohar 
Acked-by: Serge Hallyn

xattr: define vfs_getxattr_alloc and vfs_xattr_cmp

2011-07-18T16:29:39+00:00

vfs_getxattr_alloc() and vfs_xattr_cmp() are two new kernel xattr helper
functions.  vfs_getxattr_alloc() first allocates memory for the requested
xattr and then retrieves it. vfs_xattr_cmp() compares a given value with
the contents of an extended attribute.

Signed-off-by: Mimi Zohar 
Acked-by: Serge Hallyn

Cache xattr security drop check for write v2

2011-05-28T16:02:09+00:00

Some recent benchmarking on btrfs showed that a major scaling bottleneck
on large systems on btrfs is currently the xattr lookup on every write.

Why xattr lookup on every write I hear you ask?

write wants to drop suid and security related xattrs that could set o
capabilities for executables.  To do that it currently looks up
security.capability on EVERY write (even for non executables) to decide
whether to drop it or not.

In btrfs this causes an additional tree walk, hitting some per file system
locks and quite bad scalability. In a simple read workload on a 8S
system I saw over 90% CPU time in spinlocks related to that.

Chris Mason tells me this is also a problem in ext4, where it hits
the global mbcache lock.

This patch adds a simple per inode to avoid this problem.  We only
do the lookup once per file and then if there is no xattr cache
the decision. All xattr changes clear the flag.

I also used the same flag to avoid the suid check, although
that one is pretty cheap.

A file system can also set this flag when it creates the inode,
if it has a cheap way to do so.  This is done for some common file systems
in followon patches.

With this patch a major part of the lock contention disappears
for btrfs. Some testing on smaller systems didn't show significant
performance changes, but at least it helps the larger systems
and is generally more efficient.

v2: Rename is_sgid. add file system helper.
Cc: chris.mason@oracle.com
Cc: josef@redhat.com
Cc: viro@zeniv.linux.org.uk
Cc: agruen@linbit.com
Cc: Serge E. Hallyn 
Signed-off-by: Andi Kleen 
Signed-off-by: Al Viro

xattr: Fix error results for non-existent / invisible attributes

2011-05-27T13:43:00+00:00

Return -ENODATA when trying to read a user.* attribute which cannot
exist: user space otherwise does not have a reasonable way to
distinguish between non-existent and inaccessible attributes.

Likewise, return -ENODATA when an unprivileged process tries to read a
trusted.* attribute: to unprivileged processes, those attributes are
invisible (listxattr() won't include them).

Related to this bug report: https://bugzilla.redhat.com/660613

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

vfs: Pass setxattr(2) flags properly

2011-04-21T14:34:44+00:00

For some reason generic_setxattr() did not pass flags (XATTR_CREATE,
XATTR_REPLACE) to the filesystem specific helper. This caused that
setxattr(2) syscall just ignored these flags.

Fix the bug by passing flags correctly.

Signed-off-by: Jan Kara 
Acked-by: Christoph Hellwig 
Signed-off-by: Linus Torvalds

userns: rename is_owner_or_cap to inode_owner_or_capable

2011-03-24T02:47:13+00:00

And give it a kernel-doc comment.

[akpm@linux-foundation.org: btrfs changed in linux-next]
Signed-off-by: Serge E. Hallyn 
Cc: "Eric W. Biederman" 
Cc: Daniel Lezcano 
Acked-by: David Howells 
Cc: James Morris 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs: xattr_handler table should be const

2010-05-21T22:31:18+00:00

The entries in xattr handler table should be immutable (ie const)
like other operation tables.

Later patches convert common filesystems. Uncoverted filesystems
will still work, but will generate a compiler warning.

Signed-off-by: Stephen Hemminger 
Signed-off-by: Al Viro

sanitize xattr handler prototypes

2009-12-16T17:16:49+00:00

Add a flags argument to struct xattr_handler and pass it to all xattr
handler methods.  This allows using the same methods for multiple
handlers, e.g. for the ACL methods which perform exactly the same action
for the access and default ACLs, just using a different underlying
attribute.  With a little more groundwork it'll also allow sharing the
methods for the regular user/trusted/secure handlers in extN, ocfs2 and
jffs2 like it's already done for xfs in this patch.

Also change the inode argument to the handlers to a dentry to allow
using the handlers mechnism for filesystems that require it later,
e.g. cifs.

[with GFS2 bits updated by Steven Whitehouse ]

Signed-off-by: Christoph Hellwig 
Reviewed-by: James Morris 
Acked-by: Joel Becker 
Signed-off-by: Al Viro

VFS: Factor out part of vfs_setxattr so it can be called from the SELinux hook for inode_setsecctx.

2009-09-10T00:11:22+00:00

This factors out the part of the vfs_setxattr function that performs the
setting of the xattr and its notification. This is needed so the SELinux
implementation of inode_setsecctx can handle the setting of the xattr while
maintaining the proper separation of layers.

Signed-off-by: David P. Quigley 
Acked-by: Serge Hallyn 
Signed-off-by: James Morris