Commit Graph

108 Commits

Author SHA1 Message Date
Linus Torvalds d102a56edb Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs fixes from Al Viro:
 "Followups to the parallel lookup work:

   - update docs

   - restore killability of the places that used to take ->i_mutex
     killably now that we have down_write_killable() merged

   - Additionally, it turns out that I missed a prerequisite for
     security_d_instantiate() stuff - ->getxattr() wasn't the only thing
     that could be called before dentry is attached to inode; with smack
     we needed the same treatment applied to ->setxattr() as well"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  switch ->setxattr() to passing dentry and inode separately
  switch xattr_handler->set() to passing dentry and inode separately
  restore killability of old mutex_lock_killable(&inode->i_mutex) users
  add down_write_killable_nested()
  update D/f/directory-locking
2016-05-27 17:14:05 -07:00
Al Viro 3767e255b3 switch ->setxattr() to passing dentry and inode separately
smack ->d_instantiate() uses ->setxattr(), so to be able to call it before
we'd hashed the new dentry and attached it to inode, we need ->setxattr()
instances getting the inode as an explicit argument rather than obtaining
it from dentry.

Similar change for ->getxattr() had been done in commit ce23e64.  Unlike
->getxattr() (which is used by both selinux and smack instances of
->d_instantiate()) ->setxattr() is used only by smack one and unfortunately
it got missed back then.

Reported-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Tested-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-27 20:09:16 -04:00
Linus Torvalds 0121a32201 Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
Pull overlayfs update from Miklos Szeredi:
 "The meat of this is a change to use the mounter's credentials for
  operations that require elevated privileges (such as whiteout
  creation).  This fixes behavior under user namespaces as well as being
  a nice cleanup"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: Do d_type check only if work dir creation was successful
  ovl: update documentation
  ovl: override creds with the ones from the superblock mounter
2016-05-27 16:44:39 -07:00
Vivek Goyal 21765194ce ovl: Do d_type check only if work dir creation was successful
d_type check requires successful creation of workdir as iterates
through work dir and expects work dir to be present in it. If that's
not the case, this check will always return d_type not supported even
if underlying filesystem might be supporting it.

So don't do this check if work dir creation failed in previous step.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-05-27 10:18:56 +02:00
Antonio Murdaca 3fe6e52f06 ovl: override creds with the ones from the superblock mounter
In user namespace the whiteout creation fails with -EPERM because the
current process isn't capable(CAP_SYS_ADMIN) when setting xattr.

A simple reproducer:

$ mkdir upper lower work merged lower/dir
$ sudo mount -t overlay overlay -olowerdir=lower,upperdir=upper,workdir=work merged
$ unshare -m -p -f -U -r bash

Now as root in the user namespace:

\# touch merged/dir/{1,2,3} # this will force a copy up of lower/dir
\# rm -fR merged/*

This ends up failing with -EPERM after the files in dir has been
correctly deleted:

unlinkat(4, "2", 0)                     = 0
unlinkat(4, "1", 0)                     = 0
unlinkat(4, "3", 0)                     = 0
close(4)                                = 0
unlinkat(AT_FDCWD, "merged/dir", AT_REMOVEDIR) = -1 EPERM (Operation not
permitted)

Interestingly, if you don't place files in merged/dir you can remove it,
meaning if upper/dir does not exist, creating the char device file works
properly in that same location.

This patch uses ovl_sb_creator_cred() to get the cred struct from the
superblock mounter and override the old cred with these new ones so that
the whiteout creation is possible because overlay is wrong in assuming that
the creds it will get with prepare_creds will be in the initial user
namespace.  The old cap_raise game is removed in favor of just overriding
the old cred struct.

This patch also drops from ovl_copy_up_one() the following two lines:

override_cred->fsuid = stat->uid;
override_cred->fsgid = stat->gid;

This is because the correct uid and gid are taken directly with the stat
struct and correctly set with ovl_set_attr().

Signed-off-by: Antonio Murdaca <runcom@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-05-27 08:55:26 +02:00
Al Viro 002354112f restore killability of old mutex_lock_killable(&inode->i_mutex) users
The ones that are taking it exclusive, that is...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-26 00:13:25 -04:00
Al Viro 0e0162bb8c Merge branch 'ovl-fixes' into for-linus
Backmerge to resolve a conflict in ovl_lookup_real();
"ovl_lookup_real(): use lookup_one_len_unlocked()" instead,
but it was too late in the cycle to rebase.
2016-05-17 02:17:59 -04:00
Miklos Szeredi 38b78a5f18 ovl: ignore permissions on underlying lookup
Generally permission checking is not necessary when overlayfs looks up a
dentry on one of the underlying layers, since search permission on base
directory was already checked in ovl_permission().

More specifically using lookup_one_len() causes a problem when the lower
directory lacks search permission for a specific user while the upper
directory does have search permission.  Since lookups are cached, this
causes inconsistency in behavior: success depends on who did the first
lookup.

So instead use lookup_hash() which doesn't do the permission check.

Reported-by: Ignacy Gawędzki <ignacy.gawedzki@green-communications.fr>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-05-10 23:58:18 -04:00
Al Viro 9902af79c0 parallel lookups: actual switch to rwsem
ta-da!

The main issue is the lack of down_write_killable(), so the places
like readdir.c switched to plain inode_lock(); once killable
variants of rwsem primitives appear, that'll be dealt with.

lockdep side also might need more work

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-02 19:49:28 -04:00
Al Viro b9e1d435fd ovl_lookup_real(): use lookup_one_len_unlocked()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-05-02 19:47:24 -04:00
Al Viro 84695ffee7 Merge getxattr prototype change into work.lookups
The rest of work.xattr stuff isn't needed for this branch
2016-05-02 19:45:47 -04:00
Al Viro ce23e64013 ->getxattr(): pass dentry and inode as separate arguments
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-04-11 00:48:00 -04:00
Miklos Szeredi d101a12595 fs: add file_dentry()
This series fixes bugs in nfs and ext4 due to 4bacc9c923 ("overlayfs:
Make f_path always point to the overlay and f_inode to the underlay").

Regular files opened on overlayfs will result in the file being opened on
the underlying filesystem, while f_path points to the overlayfs
mount/dentry.

This confuses filesystems which get the dentry from struct file and assume
it's theirs.

Add a new helper, file_dentry() [*], to get the filesystem's own dentry
from the file.  This checks file->f_path.dentry->d_flags against
DCACHE_OP_REAL, and returns file->f_path.dentry if DCACHE_OP_REAL is not
set (this is the common, non-overlayfs case).

In the uncommon case it will call into overlayfs's ->d_real() to get the
underlying dentry, matching file_inode(file).

The reason we need to check against the inode is that if the file is copied
up while being open, d_real() would return the upper dentry, while the open
file comes from the lower dentry.

[*] If possible, it's better simply to use file_inode() instead.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Tested-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: <stable@vger.kernel.org> # v4.2
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Daniel Axtens <dja@axtens.net>
2016-03-26 16:14:37 -04:00
Miklos Szeredi 6986c012fa ovl: cleanup unused var in rename2
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-03-21 17:31:46 +01:00
Miklos Szeredi 56656e960b ovl: rename is_merge to is_lowest
The 'is_merge' is an historical naming from when only a single lower layer
could exist.  With the introduction of multiple lower layers the meaning of
this flag was changed to mean only the "lowest layer" (while all lower
layers were being merged).

So now 'is_merge' is inaccurate and hence renaming to 'is_lowest'

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-03-21 17:31:46 +01:00
Sohom Bhattacharjee f134f24465 ovl: fixed coding style warning
This patch fixes a newline warning found by the checkpatch.pl tool

Signed-off-by: Sohom-Bhattacharjee <soham.bhattacharjee15@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-03-21 17:31:45 +01:00
Vivek Goyal 45aebeaf4f ovl: Ensure upper filesystem supports d_type
In some instances xfs has been created with ftype=0 and there if a file
on lower fs is removed, overlay leaves a whiteout in upper fs but that
whiteout does not get filtered out and is visible to overlayfs users.

And reason it does not get filtered out because upper filesystem does
not report file type of whiteout as DT_CHR during iterate_dir().

So it seems to be a requirement that upper filesystem support d_type for
overlayfs to work properly. Do this check during mount and fail if d_type
is not supported.

Suggested-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-03-21 17:31:45 +01:00
David Howells fb5bb2c3b7 ovl: Warn on copy up if a process has a R/O fd open to the lower file
Print a warning when overlayfs copies up a file if the process that
triggered the copy up has a R/O fd open to the lower file being copied up.

This can help catch applications that do things like the following:

	fd1 = open("foo", O_RDONLY);
	fd2 = open("foo", O_RDWR);

where they expect fd1 and fd2 to refer to the same file - which will no
longer be the case post-copy up.

With this patch, the following commands:

	bash 5</mnt/a/foo128
	6<>/mnt/a/foo128

assuming /mnt/a/foo128 to be an un-copied up file on an overlay will
produce the following warning in the kernel log:

	overlayfs: Copying up foo129, but open R/O on fd 5 which will cease
	to be coherent [pid=3818 bash]

This is enabled by setting:

	/sys/module/overlay/parameters/check_copy_up

to 1.

The warnings are ratelimited and are also limited to one warning per file -
assuming the copy up completes in each case.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-03-21 17:31:45 +01:00
Konstantin Khlebnikov 07f2af7bfd ovl: honor flag MS_SILENT at mount
This patch hides error about missing lowerdir if MS_SILENT is set.

We use mount(NULL, "/", "overlay", MS_SILENT, NULL) for testing support of
overlayfs: syscall returns -ENODEV if it's not supported. Otherwise kernel
automatically loads module and returns -EINVAL because lowerdir is missing.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-03-21 17:31:45 +01:00
Miklos Szeredi 11f3710417 ovl: verify upper dentry before unlink and rename
Unlink and rename in overlayfs checked the upper dentry for staleness by
verifying upper->d_parent against upperdir.  However the dentry can go
stale also by being unhashed, for example.

Expand the verification to actually look up the name again (under parent
lock) and check if it matches the upper dentry.  This matches what the VFS
does before passing the dentry to filesytem's unlink/rename methods, which
excludes any inconsistency caused by overlayfs.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-03-21 17:31:44 +01:00
Konstantin Khlebnikov b81de061fa ovl: copy new uid/gid into overlayfs runtime inode
Overlayfs must update uid/gid after chown, otherwise functions
like inode_owner_or_capable() will check user against stale uid.
Catched by xfstests generic/087, it chowns file and calls utimes.

Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Cc: <stable@vger.kernel.org>
2016-03-03 17:17:46 +01:00
Konstantin Khlebnikov 45d1173896 ovl: ignore lower entries when checking purity of non-directory entries
After rename file dentry still holds reference to lower dentry from
previous location. This doesn't matter for data access because data comes
from upper dentry. But this stale lower dentry taints dentry at new
location and turns it into non-pure upper. Such file leaves visible
whiteout entry after remove in directory which shouldn't have whiteouts at
all.

Overlayfs already tracks pureness of file location in oe->opaque.  This
patch just uses that for detecting actual path type.

Comment from Vivek Goyal's patch:

Here are the details of the problem. Do following.

$ mkdir upper lower work merged upper/dir/
$ touch lower/test
$ sudo mount -t overlay overlay -olowerdir=lower,upperdir=upper,workdir=
work merged
$ mv merged/test merged/dir/
$ rm merged/dir/test
$ ls -l merged/dir/
/usr/bin/ls: cannot access merged/dir/test: No such file or directory
total 0
c????????? ? ? ? ?            ? test

Basic problem seems to be that once a file has been unlinked, a whiteout
has been left behind which was not needed and hence it becomes visible.

Whiteout is visible because parent dir is of not type MERGE, hence
od->is_real is set during ovl_dir_open(). And that means ovl_iterate()
passes on iterate handling directly to underlying fs. Underlying fs does
not know/filter whiteouts so it becomes visible to user.

Why did we leave a whiteout to begin with when we should not have.
ovl_do_remove() checks for OVL_TYPE_PURE_UPPER() and does not leave
whiteout if file is pure upper. In this case file is not found to be pure
upper hence whiteout is left.

So why file was not PURE_UPPER in this case? I think because dentry is
still carrying some leftover state which was valid before rename. For
example, od->numlower was set to 1 as it was a lower file. After rename,
this state is not valid anymore as there is no such file in lower.

Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Reported-by: Viktor Stanchev <me@viktorstanchev.com>
Suggested-by: Vivek Goyal <vgoyal@redhat.com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=109611
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Cc: <stable@vger.kernel.org>
2016-03-03 17:17:45 +01:00
Rui Wang ce9113bbcb ovl: fix getcwd() failure after unsuccessful rmdir
ovl_remove_upper() should do d_drop() only after it successfully
removes the dir, otherwise a subsequent getcwd() system call will
fail, breaking userspace programs.

This is to fix: https://bugzilla.kernel.org/show_bug.cgi?id=110491

Signed-off-by: Rui Wang <rui.y.wang@intel.com>
Reviewed-by: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Cc: <stable@vger.kernel.org>
2016-03-03 17:17:45 +01:00
Konstantin Khlebnikov b5891cfab0 ovl: fix working on distributed fs as lower layer
This adds missing .d_select_inode into alternative dentry_operations.

Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Fixes: 7c03b5d45b ("ovl: allow distributed fs as lower layer")
Fixes: 4bacc9c923 ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay")
Reviewed-by: Nikolay Borisov <kernel@kyup.com>
Tested-by: Nikolay Borisov <kernel@kyup.com>
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Cc: <stable@vger.kernel.org> # 4.2+
2016-03-03 17:17:45 +01:00
Al Viro 5955102c99 wrappers for ->i_mutex access
parallel to mutex_{lock,unlock,trylock,is_locked,lock_nested},
inode_foo(inode) being mutex_foo(&inode->i_mutex).

Please, use those for access to ->i_mutex; over the coming cycle
->i_mutex will become rwsem, with ->lookup() done with it held
only shared.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-01-22 18:04:28 -05:00
Linus Torvalds eae21770b4 Merge branch 'akpm' (patches from Andrew)
Merge third patch-bomb from Andrew Morton:
 "I'm pretty much done for -rc1 now:

   - the rest of MM, basically

   - lib/ updates

   - checkpatch, epoll, hfs, fatfs, ptrace, coredump, exit

   - cpu_mask simplifications

   - kexec, rapidio, MAINTAINERS etc, etc.

   - more dma-mapping cleanups/simplifications from hch"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (109 commits)
  MAINTAINERS: add/fix git URLs for various subsystems
  mm: memcontrol: add "sock" to cgroup2 memory.stat
  mm: memcontrol: basic memory statistics in cgroup2 memory controller
  mm: memcontrol: do not uncharge old page in page cache replacement
  Documentation: cgroup: add memory.swap.{current,max} description
  mm: free swap cache aggressively if memcg swap is full
  mm: vmscan: do not scan anon pages if memcg swap limit is hit
  swap.h: move memcg related stuff to the end of the file
  mm: memcontrol: replace mem_cgroup_lruvec_online with mem_cgroup_online
  mm: vmscan: pass memcg to get_scan_count()
  mm: memcontrol: charge swap to cgroup2
  mm: memcontrol: clean up alloc, online, offline, free functions
  mm: memcontrol: flatten struct cg_proto
  mm: memcontrol: rein in the CONFIG space madness
  net: drop tcp_memcontrol.c
  mm: memcontrol: introduce CONFIG_MEMCG_LEGACY_KMEM
  mm: memcontrol: allow to disable kmem accounting for cgroup2
  mm: memcontrol: account "kmem" consumers in cgroup2 memory controller
  mm: memcontrol: move kmem accounting code to CONFIG_MEMCG
  mm: memcontrol: separate kmem code from legacy tcp accounting code
  ...
2016-01-21 12:32:08 -08:00
Linus Torvalds e9f57ebcba Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
Pull overlayfs updates from Miklos Szeredi:
 "This contains several bug fixes and a new mount option
  'default_permissions' that allows read-only exported NFS
  filesystems to be used as lower layer"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: check dentry positiveness in ovl_cleanup_whiteouts()
  ovl: setattr: check permissions before copy-up
  ovl: root: copy attr
  ovl: move super block magic number to magic.h
  ovl: use a minimal buffer in ovl_copy_xattr
  ovl: allow zero size xattr
  ovl: default permissions
2016-01-21 12:20:46 -08:00
Andrew Morton e458bcd16f fs/overlayfs/super.c needs pagemap.h
i386 allmodconfig:

  In file included from fs/overlayfs/super.c:10:0:
  fs/overlayfs/super.c: In function 'ovl_fill_super':
  include/linux/fs.h:898:36: error: 'PAGE_CACHE_SIZE' undeclared (first use in this function)
   #define MAX_LFS_FILESIZE (((loff_t)PAGE_CACHE_SIZE << (BITS_PER_LONG-1))-1)
                                      ^
  fs/overlayfs/super.c:939:19: note: in expansion of macro 'MAX_LFS_FILESIZE'
    sb->s_maxbytes = MAX_LFS_FILESIZE;
                     ^
  include/linux/fs.h:898:36: note: each undeclared identifier is reported only once for each function it appears in
   #define MAX_LFS_FILESIZE (((loff_t)PAGE_CACHE_SIZE << (BITS_PER_LONG-1))-1)
                                      ^
  fs/overlayfs/super.c:939:19: note: in expansion of macro 'MAX_LFS_FILESIZE'
    sb->s_maxbytes = MAX_LFS_FILESIZE;
                     ^

Cc: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 17:09:18 -08:00
Al Viro fceef393a5 switch ->get_link() to delayed_call, kill ->put_link()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-12-30 13:01:03 -05:00
Konstantin Khlebnikov 84889d4933 ovl: check dentry positiveness in ovl_cleanup_whiteouts()
This patch fixes kernel crash at removing directory which contains
whiteouts from lower layers.

Cache of directory content passed as "list" contains entries from all
layers, including whiteouts from lower layers. So, lookup in upper dir
(moved into work at this stage) will return negative entry. Plus this
cache is filled long before and we can race with external removal.

Example:
 mkdir -p lower0/dir lower1/dir upper work overlay
 touch lower0/dir/a lower0/dir/b
 mknod lower1/dir/a c 0 0
 mount -t overlay none overlay -o lowerdir=lower1:lower0,upperdir=upper,workdir=work
 rm -fr overlay/dir

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Cc: <stable@vger.kernel.org> # 3.18+
2015-12-11 16:30:49 +01:00
Miklos Szeredi cf9a6784f7 ovl: setattr: check permissions before copy-up
Without this copy-up of a file can be forced, even without actually being
allowed to do anything on the file.

[Arnd Bergmann] include <linux/pagemap.h> for PAGE_CACHE_SIZE (used by
MAX_LFS_FILESIZE definition).

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Cc: <stable@vger.kernel.org>
2015-12-11 16:30:49 +01:00
Miklos Szeredi ed06e06977 ovl: root: copy attr
We copy i_uid and i_gid of underlying inode into overlayfs inode.  Except
for the root inode.

Fix this omission.

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Cc: <stable@vger.kernel.org>
2015-12-09 16:11:59 +01:00
Al Viro 6b2553918d replace ->follow_link() with new method that could stay in RCU mode
new method: ->get_link(); replacement of ->follow_link().  The differences
are:
	* inode and dentry are passed separately
	* might be called both in RCU and non-RCU mode;
the former is indicated by passing it a NULL dentry.
	* when called that way it isn't allowed to block
and should return ERR_PTR(-ECHILD) if it needs to be called
in non-RCU mode.

It's a flagday change - the old method is gone, all in-tree instances
converted.  Conversion isn't hard; said that, so far very few instances
do not immediately bail out when called in RCU mode.  That'll change
in the next commits.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-12-08 22:41:54 -05:00
Al Viro 0f7ff2dabb ovl: get rid of the dead code left from broken (and disabled) optimizations
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-12-06 12:31:07 -05:00
Miklos Szeredi acff81ec2c ovl: fix permission checking for setattr
[Al Viro] The bug is in being too enthusiastic about optimizing ->setattr()
away - instead of "copy verbatim with metadata" + "chmod/chown/utimes"
(with the former being always safe and the latter failing in case of
insufficient permissions) it tries to combine these two.  Note that copyup
itself will have to do ->setattr() anyway; _that_ is where the elevated
capabilities are right.  Having these two ->setattr() (one to set verbatim
copy of metadata, another to do what overlayfs ->setattr() had been asked
to do in the first place) combined is where it breaks.

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Cc: <stable@vger.kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-12-06 12:28:23 -05:00
Stephen Hemminger 257f871993 ovl: move super block magic number to magic.h
The overlayfs file system is not recognized by programs
like tail because the magic number is not in standard header location.

Move it so that the value will propagate on for the GNU library
and utilities. Needs to go in the fstatfs manual page as well.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
2015-11-10 17:13:35 +01:00
Vito Caputo e4ad29fa0d ovl: use a minimal buffer in ovl_copy_xattr
Rather than always allocating the high-order XATTR_SIZE_MAX buffer
which is costly and prone to failure, only allocate what is needed and
realloc if necessary.

Fixes https://github.com/coreos/bugs/issues/489

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Cc: <stable@vger.kernel.org>
2015-11-10 17:08:42 +01:00
Miklos Szeredi 97daf8b97a ovl: allow zero size xattr
When ovl_copy_xattr() encountered a zero size xattr no more xattrs were
copied and the function returned success.  This is clearly not the desired
behavior.

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Cc: <stable@vger.kernel.org>
2015-11-10 17:08:41 +01:00
Linus Torvalds 4bb0fb57f3 Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
Pull overlayfs bug fixes from Miklos Szeredi:
 "This contains fixes for bugs that appeared in earlier kernels (all are
  marked for -stable)"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: free lower_mnt array in ovl_put_super
  ovl: free stack of paths in ovl_fill_super
  ovl: fix open in stacked overlay
  ovl: fix dentry reference leak
  ovl: use O_LARGEFILE in ovl_copy_up()
2015-10-31 14:49:19 -07:00
Miklos Szeredi 8d3095f4ad ovl: default permissions
Add mount option "default_permissions" to alter the way permissions are
calculated.

Without this option and prior to this patch permissions were calculated by
underlying lower or upper filesystem.

With this option the permissions are calculated by overlayfs based on the
file owner, group and mode bits.

This has significance for example when a read-only exported NFS filesystem
is used as a lower layer.  In this case the underlying NFS filesystem will
reply with EROFS, in which case all we know is that the filesystem is
read-only.  But that's not what we are interested in, we are interested in
whether the access would be allowed if the filesystem wasn't read-only; the
server doesn't tell us that, and would need updating at various levels,
which doesn't seem practicable.

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
2015-10-12 17:11:44 +02:00
Konstantin Khlebnikov 5ffdbe8bf1 ovl: free lower_mnt array in ovl_put_super
This fixes memory leak after umount.

Kmemleak report:

unreferenced object 0xffff8800ba791010 (size 8):
  comm "mount", pid 2394, jiffies 4294996294 (age 53.920s)
  hex dump (first 8 bytes):
    20 1c 13 02 00 88 ff ff                           .......
  backtrace:
    [<ffffffff811f8cd4>] create_object+0x124/0x2c0
    [<ffffffff817a059b>] kmemleak_alloc+0x7b/0xc0
    [<ffffffff811dffe6>] __kmalloc+0x106/0x340
    [<ffffffffa0152bfc>] ovl_fill_super+0x55c/0x9b0 [overlay]
    [<ffffffff81200ac4>] mount_nodev+0x54/0xa0
    [<ffffffffa0152118>] ovl_mount+0x18/0x20 [overlay]
    [<ffffffff81201ab3>] mount_fs+0x43/0x170
    [<ffffffff81220d34>] vfs_kern_mount+0x74/0x170
    [<ffffffff812233ad>] do_mount+0x22d/0xdf0
    [<ffffffff812242cb>] SyS_mount+0x7b/0xc0
    [<ffffffff817b6bee>] entry_SYSCALL_64_fastpath+0x12/0x76
    [<ffffffffffffffff>] 0xffffffffffffffff

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Fixes: dd662667e6 ("ovl: add mutli-layer infrastructure")
Cc: <stable@vger.kernel.org> # v4.0+
2015-10-12 17:11:44 +02:00
Konstantin Khlebnikov 0f95502ad8 ovl: free stack of paths in ovl_fill_super
This fixes small memory leak after mount.

Kmemleak report:

unreferenced object 0xffff88003683fe00 (size 16):
  comm "mount", pid 2029, jiffies 4294909563 (age 33.380s)
  hex dump (first 16 bytes):
    20 27 1f bb 00 88 ff ff 40 4b 0f 36 02 88 ff ff   '......@K.6....
  backtrace:
    [<ffffffff811f8cd4>] create_object+0x124/0x2c0
    [<ffffffff817a059b>] kmemleak_alloc+0x7b/0xc0
    [<ffffffff811dffe6>] __kmalloc+0x106/0x340
    [<ffffffffa01b7a29>] ovl_fill_super+0x389/0x9a0 [overlay]
    [<ffffffff81200ac4>] mount_nodev+0x54/0xa0
    [<ffffffffa01b7118>] ovl_mount+0x18/0x20 [overlay]
    [<ffffffff81201ab3>] mount_fs+0x43/0x170
    [<ffffffff81220d34>] vfs_kern_mount+0x74/0x170
    [<ffffffff812233ad>] do_mount+0x22d/0xdf0
    [<ffffffff812242cb>] SyS_mount+0x7b/0xc0
    [<ffffffff817b6bee>] entry_SYSCALL_64_fastpath+0x12/0x76
    [<ffffffffffffffff>] 0xffffffffffffffff

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Fixes: a78d9f0d5d ("ovl: support multiple lower layers")
Cc: <stable@vger.kernel.org> # v4.0+
2015-10-12 17:11:43 +02:00
Miklos Szeredi 1c8a47df36 ovl: fix open in stacked overlay
If two overlayfs filesystems are stacked on top of each other, then we need
recursion in ovl_d_select_inode().

I guess d_backing_inode() is supposed to do that.  But currently it doesn't
and that functionality is open coded in vfs_open().  This is now copied
into ovl_d_select_inode() to fix this regression.

Reported-by: Alban Crequy <alban.crequy@gmail.com>
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Fixes: 4bacc9c923 ("overlayfs: Make f_path always point to the overlay...")
Cc: David Howells <dhowells@redhat.com>
Cc: <stable@vger.kernel.org> # v4.2+
2015-10-12 15:56:20 +02:00
David Howells ab79efab0a ovl: fix dentry reference leak
In ovl_copy_up_locked(), newdentry is leaked if the function exits through
out_cleanup as this just to out after calling ovl_cleanup() - which doesn't
actually release the ref on newdentry.

The out_cleanup segment should instead exit through out2 as certainly
newdentry leaks - and possibly upper does also, though this isn't caught
given the catch of newdentry.

Without this fix, something like the following is seen:

	BUG: Dentry ffff880023e9eb20{i=f861,n=#ffff880023e82d90} still in use (1) [unmount of tmpfs tmpfs]
	BUG: Dentry ffff880023ece640{i=0,n=bigfile}  still in use (1) [unmount of tmpfs tmpfs]

when unmounting the upper layer after an error occurred in copyup.

An error can be induced by creating a big file in a lower layer with
something like:

	dd if=/dev/zero of=/lower/a/bigfile bs=65536 count=1 seek=$((0xf000))

to create a large file (4.1G).  Overlay an upper layer that is too small
(on tmpfs might do) and then induce a copy up by opening it writably.

Reported-by: Ulrich Obergfell <uobergfe@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Cc: <stable@vger.kernel.org> # v3.18+
2015-10-12 15:56:20 +02:00
David Howells 0480334fa6 ovl: use O_LARGEFILE in ovl_copy_up()
Open the lower file with O_LARGEFILE in ovl_copy_up().

Pass O_LARGEFILE unconditionally in ovl_copy_up_data() as it's purely for
catching 32-bit userspace dealing with a file large enough that it'll be
mishandled if the application isn't aware that there might be an integer
overflow.  Inside the kernel, there shouldn't be any problems.

Reported-by: Ulrich Obergfell <uobergfe@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Cc: <stable@vger.kernel.org> # v3.18+
2015-10-12 15:56:20 +02:00
Kees Cook a068acf2ee fs: create and use seq_show_option for escaping
Many file systems that implement the show_options hook fail to correctly
escape their output which could lead to unescaped characters (e.g.  new
lines) leaking into /proc/mounts and /proc/[pid]/mountinfo files.  This
could lead to confusion, spoofed entries (resulting in things like
systemd issuing false d-bus "mount" notifications), and who knows what
else.  This looks like it would only be the root user stepping on
themselves, but it's possible weird things could happen in containers or
in other situations with delegated mount privileges.

Here's an example using overlay with setuid fusermount trusting the
contents of /proc/mounts (via the /etc/mtab symlink).  Imagine the use
of "sudo" is something more sneaky:

  $ BASE="ovl"
  $ MNT="$BASE/mnt"
  $ LOW="$BASE/lower"
  $ UP="$BASE/upper"
  $ WORK="$BASE/work/ 0 0
  none /proc fuse.pwn user_id=1000"
  $ mkdir -p "$LOW" "$UP" "$WORK"
  $ sudo mount -t overlay -o "lowerdir=$LOW,upperdir=$UP,workdir=$WORK" none /mnt
  $ cat /proc/mounts
  none /root/ovl/mnt overlay rw,relatime,lowerdir=ovl/lower,upperdir=ovl/upper,workdir=ovl/work/ 0 0
  none /proc fuse.pwn user_id=1000 0 0
  $ fusermount -u /proc
  $ cat /proc/mounts
  cat: /proc/mounts: No such file or directory

This fixes the problem by adding new seq_show_option and
seq_show_option_n helpers, and updating the vulnerable show_option
handlers to use them as needed.  Some, like SELinux, need to be open
coded due to unusual existing escape mechanisms.

[akpm@linux-foundation.org: add lost chunk, per Kees]
[keescook@chromium.org: seq_show_option should be using const parameters]
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Acked-by: Jan Kara <jack@suse.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Cc: J. R. Okajima <hooanon05g@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-04 16:54:41 -07:00
Al Viro 9391dd00d1 fix a braino in ovl_d_select_inode()
when opening a directory we want the overlayfs inode, not one from
the topmost layer.

Reported-By: Andrey Jr. Melnikov <temnota.am@gmail.com>
Tested-By: Andrey Jr. Melnikov <temnota.am@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-07-12 11:22:05 -04:00
Linus Torvalds 1dc51b8288 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull more vfs updates from Al Viro:
 "Assorted VFS fixes and related cleanups (IMO the most interesting in
  that part are f_path-related things and Eric's descriptor-related
  stuff).  UFS regression fixes (it got broken last cycle).  9P fixes.
  fs-cache series, DAX patches, Jan's file_remove_suid() work"

[ I'd say this is much more than "fixes and related cleanups".  The
  file_table locking rule change by Eric Dumazet is a rather big and
  fundamental update even if the patch isn't huge.   - Linus ]

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (49 commits)
  9p: cope with bogus responses from server in p9_client_{read,write}
  p9_client_write(): avoid double p9_free_req()
  9p: forgetting to cancel request on interrupted zero-copy RPC
  dax: bdev_direct_access() may sleep
  block: Add support for DAX reads/writes to block devices
  dax: Use copy_from_iter_nocache
  dax: Add block size note to documentation
  fs/file.c: __fget() and dup2() atomicity rules
  fs/file.c: don't acquire files->file_lock in fd_install()
  fs:super:get_anon_bdev: fix race condition could cause dev exceed its upper limitation
  vfs: avoid creation of inode number 0 in get_next_ino
  namei: make set_root_rcu() return void
  make simple_positive() public
  ufs: use dir_pages instead of ufs_dir_pages()
  pagemap.h: move dir_pages() over there
  remove the pointless include of lglock.h
  fs: cleanup slight list_entry abuse
  xfs: Correctly lock inode when removing suid and file capabilities
  fs: Call security_ops->inode_killpriv on truncate
  fs: Provide function telling whether file_remove_privs() will do anything
  ...
2015-07-04 19:36:06 -07:00
Linus Torvalds 320cd413fa Merge branch 'overlayfs-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
Pull overlayfs updates from Miklos Szeredi:
 "This relaxes the requirements on the lower layer filesystem: now ones
  that implement .d_revalidate, such as NFS, can be used.

  Upper layer filesystems still has the "no .d_revalidate" requirement.

  Also a bad interaction with jffs2 locking has been fixed"

* 'overlayfs-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: lookup whiteouts outside iterate_dir()
  ovl: allow distributed fs as lower layer
  ovl: don't traverse automount points
2015-07-02 11:23:00 -07:00
Linus Torvalds 052b398a43 Merge branch 'for-linus-1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs updates from Al Viro:
 "In this pile: pathname resolution rewrite.

   - recursion in link_path_walk() is gone.

   - nesting limits on symlinks are gone (the only limit remaining is
     that the total amount of symlinks is no more than 40, no matter how
     nested).

   - "fast" (inline) symlinks are handled without leaving rcuwalk mode.

   - stack footprint (independent of the nesting) is below kilobyte now,
     about on par with what it used to be with one level of nested
     symlinks and ~2.8 times lower than it used to be in the worst case.

   - struct nameidata is entirely private to fs/namei.c now (not even
     opaque pointers are being passed around).

   - ->follow_link() and ->put_link() calling conventions had been
     changed; all in-tree filesystems converted, out-of-tree should be
     able to follow reasonably easily.

     For out-of-tree conversions, see Documentation/filesystems/porting
     for details (and in-tree filesystems for examples of conversion).

  That has sat in -next since mid-May, seems to survive all testing
  without regressions and merges clean with v4.1"

* 'for-linus-1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (131 commits)
  turn user_{path_at,path,lpath,path_dir}() into static inlines
  namei: move saved_nd pointer into struct nameidata
  inline user_path_create()
  inline user_path_parent()
  namei: trim do_last() arguments
  namei: stash dfd and name into nameidata
  namei: fold path_cleanup() into terminate_walk()
  namei: saner calling conventions for filename_parentat()
  namei: saner calling conventions for filename_create()
  namei: shift nameidata down into filename_parentat()
  namei: make filename_lookup() reject ERR_PTR() passed as name
  namei: shift nameidata inside filename_lookup()
  namei: move putname() call into filename_lookup()
  namei: pass the struct path to store the result down into path_lookupat()
  namei: uninline set_root{,_rcu}()
  namei: be careful with mountpoint crossings in follow_dotdot_rcu()
  Documentation: remove outdated information from automount-support.txt
  get rid of assorted nameidata-related debris
  lustre: kill unused helper
  lustre: kill unused macro (LOOKUP_CONTINUE)
  ...
2015-06-22 12:51:21 -07:00