linux-toradex.git/fs/xattr.c, branch v4.4.142

lsm: fix smack_inode_removexattr and xattr_getsecurity memleak

2017-10-12T09:27:32+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 
Signed-off-by: Greg Kroah-Hartman

fs/xattr.c: zero out memory copied to userspace in getxattr

2017-05-20T12:27:01+00:00

commit 81be3dee96346fbe08c31be5ef74f03f6b63cf68 upstream.

getxattr uses vmalloc to allocate memory if kzalloc fails.  This is
filled by vfs_getxattr and then copied to the userspace.  vmalloc,
however, doesn't zero out the memory so if the specific implementation
of the xattr handler is sloppy we can theoretically expose a kernel
memory.  There is no real sign this is really the case but let's make
sure this will not happen and use vzalloc instead.

Fixes: 779302e67835 ("fs/xattr.c:getxattr(): improve handling of allocation failures")
Link: http://lkml.kernel.org/r/20170306103327.2766-1-mhocko@kernel.org
Acked-by: Kees Cook 
Reported-by: Vlastimil Babka 
Signed-off-by: Michal Hocko 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

9p: xattr simplifications

2015-11-14T01:34:33+00:00

Now that the xattr handler is passed to the xattr handler operations, we
can use the same get and set operations for the user, trusted, and security
xattr namespaces.  In those namespaces, we can access the full attribute
name by "reattaching" the name prefix the vfs has skipped for us.  Add a
xattr_full_name helper to make this obvious in the code.

For the "system.posix_acl_access" and "system.posix_acl_default"
attributes, handler->prefix is the full attribute name; the suffix is the
empty string.

Signed-off-by: Andreas Gruenbacher 
Cc: Eric Van Hensbergen 
Cc: Ron Minnich 
Cc: Latchesar Ionkov 
Cc: v9fs-developer@lists.sourceforge.net
Signed-off-by: Al Viro

xattr handlers: Pass handler to operations instead of flags

2015-11-14T01:34:32+00:00

The xattr_handler operations are currently all passed a file system
specific flags value which the operations can use to disambiguate between
different handlers; some file systems use that to distinguish the xattr
namespace, for example.  In some oprations, it would be useful to also have
access to the handler prefix.  To allow that, pass a pointer to the handler
to operations instead of the flags value alone.

Signed-off-by: Andreas Gruenbacher 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Al Viro

evm: fix potential race when removing xattrs

2015-05-21T17:28:47+00:00

EVM needs to be atomically updated when removing xattrs.
Otherwise concurrent EVM verification may fail in between.
This patch fixes by moving i_mutex unlocking after calling
EVM hook. fsnotify_xattr() is also now called while locked
the same way as it is done in __vfs_setxattr_noperm.

Changelog:
- remove unused 'inode' variable.

Signed-off-by: Dmitry Kasatkin 
Signed-off-by: Mimi Zohar

new helper: audit_file()

2014-11-19T18:01:26+00:00

... for situations when we don't have any candidate in pathnames - basically,
in descriptor-based syscalls.

[Folded the build fix for !CONFIG_AUDITSYSCALL configs from Chen Gang]

Signed-off-by: Al Viro

vfs: Deduplicate code shared by xattr system calls operating on paths

2014-10-12T21:09:10+00:00

The following pairs of system calls dealing with extended attributes only
differ in their behavior on whether the symbolic link is followed (when
the named file is a symbolic link):

- setxattr() and lsetxattr()
- getxattr() and lgetxattr()
- listxattr() and llistxattr()
- removexattr() and lremovexattr()

Despite this, the implementations all had duplicated code, so this commit
redirects each of the above pairs of system calls to a corresponding
function to which different lookup flags (LOOKUP_FOLLOW or 0) are passed.

For me this reduced the stripped size of xattr.o from 8824 to 8248 bytes.

Signed-off-by: Eric Biggers 
Signed-off-by: Al Viro

simple_xattr: permit 0-size extended attributes

2014-07-23T22:10:55+00:00

If a filesystem uses simple_xattr to support user extended attributes,
LTP setxattr01 and xfstests generic/062 fail with "Cannot allocate
memory": simple_xattr_alloc()'s wrap-around test mistakenly excludes
values of zero size.  Fix that off-by-one (but apparently no filesystem
needs them yet).

Signed-off-by: Hugh Dickins 
Cc: Al Viro 
Cc: Jeff Layton 
Cc: Aristeu Rozanski 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

vfs: make lremovexattr retry once on ESTALE error

2012-12-20T23:50:11+00:00

Signed-off-by: Jeff Layton 
Signed-off-by: Al Viro

vfs: make removexattr retry once on ESTALE

2012-12-20T23:50:10+00:00

Signed-off-by: Jeff Layton 
Signed-off-by: Al Viro