Commit Graph

950 Commits

Author SHA1 Message Date
Al Viro 653a7746fa Merge remote-tracking branch 'ovl/for-viro' into for-linus
Overlayfs-related series from Miklos and Amir
2017-03-02 06:41:22 -05:00
Al Viro f6c99aad4d Merge branch 'work.namei' into for-linus 2017-03-02 06:41:12 -05:00
Amir Goldstein af7bd4dc13 vfs: create vfs helper vfs_tmpfile()
Factor out some common vfs bits from do_tmpfile()
to be used by overlayfs for concurrent copy up.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2017-02-07 15:05:04 +01:00
Eric W. Biederman 93faccbbfa fs: Better permission checking for submounts
To support unprivileged users mounting filesystems two permission
checks have to be performed: a test to see if the user allowed to
create a mount in the mount namespace, and a test to see if
the user is allowed to access the specified filesystem.

The automount case is special in that mounting the original filesystem
grants permission to mount the sub-filesystems, to any user who
happens to stumble across the their mountpoint and satisfies the
ordinary filesystem permission checks.

Attempting to handle the automount case by using override_creds
almost works.  It preserves the idea that permission to mount
the original filesystem is permission to mount the sub-filesystem.
Unfortunately using override_creds messes up the filesystems
ordinary permission checks.

Solve this by being explicit that a mount is a submount by introducing
vfs_submount, and using it where appropriate.

vfs_submount uses a new mount internal mount flags MS_SUBMOUNT, to let
sget and friends know that a mount is a submount so they can take appropriate
action.

sget and sget_userns are modified to not perform any permission checks
on submounts.

follow_automount is modified to stop using override_creds as that
has proven problemantic.

do_mount is modified to always remove the new MS_SUBMOUNT flag so
that we know userspace will never by able to specify it.

autofs4 is modified to stop using current_real_cred that was put in
there to handle the previous version of submount permission checking.

cifs is modified to pass the mountpoint all of the way down to vfs_submount.

debugfs is modified to pass the mountpoint all of the way down to
trace_automount by adding a new parameter.  To make this change easier
a new typedef debugfs_automount_t is introduced to capture the type of
the debugfs automount function.

Cc: stable@vger.kernel.org
Fixes: 069d5ac9ae ("autofs:  Fix automounts by using current_real_cred()->uid")
Fixes: aeaa4a79ff ("fs: Call d_automount with the filesystems creds")
Reviewed-by: Trond Myklebust <trond.myklebust@primarydata.com>
Reviewed-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2017-02-02 04:36:12 +13:00
Seth Forshee 1328c72700 vfs: open() with O_CREAT should not create inodes with unknown ids
may_create() rejects creation of inodes with ids which lack a
mapping into s_user_ns. However for O_CREAT may_o_create() is
is used instead. Add a similar check there.

Fixes: 036d523641 ("vfs: Don't create inodes with a uid or gid unknown to the vfs")
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2017-02-01 18:17:05 +13:00
Al Viro 4675ac39b5 namei.c: split unlazy_walk()
In all but one case, the last two arguments are NULL and 0 resp.;
almost everyone just wants to switch nameidata to non-RCU mode.
The only exception is lookup_fast(), where we have a child dentry
we want to legitimize as well.  Split these two cases.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-01-09 22:29:15 -05:00
Al Viro a89f833737 namei.c: fold the check for DCACHE_OP_REVALIDATE into d_revalidate()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-01-09 22:25:28 -05:00
Al Viro 209a7fb210 lookup_fast(): clean up the logics around the fallback to non-rcu mode
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-01-09 01:35:39 -05:00
Al Viro ad1633a151 namei: fold unlazy_link() into its sole caller
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-01-08 22:35:31 -05:00
Linus Torvalds 7c0f6ba682 Replace <asm/uaccess.h> with <linux/uaccess.h> globally
This was entirely automated, using the script by Al:

  PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>'
  sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \
        $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)

to do the replacement at the end of the merge window.

Requested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-24 11:46:01 -08:00
Linus Torvalds 231753ef78 Merge uncontroversial parts of branch 'readlink' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
Pull partial readlink cleanups from Miklos Szeredi.

This is the uncontroversial part of the readlink cleanup patch-set that
simplifies the default readlink handling.

Miklos and Al are still discussing the rest of the series.

* git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  vfs: make generic_readlink() static
  vfs: remove ".readlink = generic_readlink" assignments
  vfs: default to generic_readlink()
  vfs: replace calling i_op->readlink with vfs_readlink()
  proc/self: use generic_readlink
  ecryptfs: use vfs_get_link()
  bad_inode: add missing i_op initializers
2016-12-17 19:16:12 -08:00
Linus Torvalds 0110c350c8 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull more vfs updates from Al Viro:
 "In this pile:

   - autofs-namespace series
   - dedupe stuff
   - more struct path constification"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (40 commits)
  ocfs2: implement the VFS clone_range, copy_range, and dedupe_range features
  ocfs2: charge quota for reflinked blocks
  ocfs2: fix bad pointer cast
  ocfs2: always unlock when completing dio writes
  ocfs2: don't eat io errors during _dio_end_io_write
  ocfs2: budget for extent tree splits when adding refcount flag
  ocfs2: prohibit refcounted swapfiles
  ocfs2: add newlines to some error messages
  ocfs2: convert inode refcount test to a helper
  simple_write_end(): don't zero in short copy into uptodate
  exofs: don't mess with simple_write_{begin,end}
  9p: saner ->write_end() on failing copy into non-uptodate page
  fix gfs2_stuffed_write_end() on short copies
  fix ceph_write_end()
  nfs_write_end(): fix handling of short copies
  vfs: refactor clone/dedupe_file_range common functions
  fs: try to clone files first in vfs_copy_file_range
  vfs: misc struct path constification
  namespace.c: constify struct path passed to a bunch of primitives
  quota: constify struct path in quota_on
  ...
2016-12-17 18:44:00 -08:00
Al Viro 9763f7a4a5 Merge branch 'work.autofs' into for-linus
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-12-16 16:34:52 -05:00
Linus Torvalds ff0f962ca3 Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
Pull overlayfs updates from Miklos Szeredi:
 "This update contains:

   - try to clone on copy-up

   - allow renaming a directory

   - split source into managable chunks

   - misc cleanups and fixes

  It does not contain the read-only fd data inconsistency fix, which Al
  didn't like. I'll leave that to the next year..."

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs: (36 commits)
  ovl: fix reStructuredText syntax errors in documentation
  ovl: fix return value of ovl_fill_super
  ovl: clean up kstat usage
  ovl: fold ovl_copy_up_truncate() into ovl_copy_up()
  ovl: create directories inside merged parent opaque
  ovl: opaque cleanup
  ovl: show redirect_dir mount option
  ovl: allow setting max size of redirect
  ovl: allow redirect_dir to default to "on"
  ovl: check for emptiness of redirect dir
  ovl: redirect on rename-dir
  ovl: lookup redirects
  ovl: consolidate lookup for underlying layers
  ovl: fix nested overlayfs mount
  ovl: check namelen
  ovl: split super.c
  ovl: use d_is_dir()
  ovl: simplify lookup
  ovl: check lower existence of rename target
  ovl: rename: simplify handling of lower/merged directory
  ...
2016-12-16 10:58:12 -08:00
Miklos Szeredi 8d3e293637 Revert "vfs: rename: check backing inode being equal"
This reverts commit 9409e22acd.

Since commit 51f7e52dc9 ("ovl: share inode for hard link") there's no
need to call d_real_inode() to check two overlay inodes for equality.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-12-16 11:02:54 +01:00
Miklos Szeredi d16744ec8a vfs: make generic_readlink() static
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-12-09 16:45:04 +01:00
Miklos Szeredi dfeef68862 vfs: remove ".readlink = generic_readlink" assignments
If .readlink == NULL implies generic_readlink().

Generated by:

to_del="\.readlink.*=.*generic_readlink"
for i in `git grep -l $to_del`; do sed -i "/$to_del"/d $i; done

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-12-09 16:45:04 +01:00
Miklos Szeredi 76fca90e9f vfs: default to generic_readlink()
If i_op->readlink is NULL, but i_op->get_link is set then vfs_readlink()
defaults to calling generic_readlink().

The IOP_DEFAULT_READLINK flag indicates that the above conditions are met
and the default action can be taken.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-12-09 16:45:04 +01:00
Miklos Szeredi fd4a0edf2a vfs: replace calling i_op->readlink with vfs_readlink()
Also check d_is_symlink() in callers instead of inode->i_op->readlink
because following patches will allow NULL ->readlink for symlinks.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-12-09 16:45:04 +01:00
Al Viro 8f64fb1cce namei: fold should_follow_link() with the step into not-followed link
All callers are followed by the same boilerplate - "if it has returned
0, update nd->path/inode/seq - we are not following a symlink here".
Pull it into the function itself, renaming it into step_into().
Rename WALK_GET to WALK_FOLLOW, while we are at it - more descriptive
name.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-12-05 19:11:58 -05:00
Al Viro 31d66bcd3f namei: pass both WALK_GET and WALK_MORE to should_follow_link()
... and pull put_link() logics into it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-12-05 19:11:58 -05:00
Al Viro 1c4ff1a87e namei: invert WALK_PUT logics
... turning the condition for put_link() in walk_component() into
"WALK_MORE not passed and depth is non-zero".  Again, makes for
simpler arguments.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-12-05 19:11:57 -05:00
Al Viro 7f49b47109 namei: shift interpretation of LOOKUP_FOLLOW inside should_follow_link()
Simplifies the arguments both for it and for walk_component()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-12-05 19:11:57 -05:00
Al Viro ba8f46135a namei: saner calling conventions for mountpoint_last()
leave the result in nd->path, have caller do follow_mount() and
copy it to the final destination.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-12-05 19:11:57 -05:00
Al Viro c1d4dd2767 namei.c: get rid of user_path_parent()
direct use of filename_parentat() is just as readable

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-12-05 19:11:57 -05:00
Al Viro f0bb5aaf2c vfs: misc struct path constification
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-12-05 19:03:49 -05:00
Ian Kent fb5f51c742 vfs: change d_manage() to take a struct path
For the autofs module to be able to reliably check if a dentry is a
mountpoint in a multiple namespace environment the ->d_manage() dentry
operation will need to take a path argument instead of a dentry.

Link: http://lkml.kernel.org/r/20161011053352.27645.83962.stgit@pluto.themaw.net
Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-12-02 22:15:53 -05:00
Linus Torvalds 1a892b485f Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
Pull overlayfs updates from Miklos Szeredi:
 "This update contains fixes to the "use mounter's permission to access
  underlying layers" area, and miscellaneous other fixes and cleanups.

  No new features this time"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: use vfs_get_link()
  vfs: add vfs_get_link() helper
  ovl: use generic_readlink
  ovl: explain error values when removing acl from workdir
  ovl: Fix info leak in ovl_lookup_temp()
  ovl: during copy up, switch to mounter's creds early
  ovl: lookup: do getxattr with mounter's permission
  ovl: copy_up_xattr(): use strnlen
2016-10-14 17:23:33 -07:00
Miklos Szeredi d60874cd58 vfs: add vfs_get_link() helper
This helper is for filesystems that want to read the symlink and are better
off with the get_link() interface (returning a char *) rather than the
readlink() interface (copy into a userspace buffer).

Also call the LSM hook for readlink (not get_link) since this is for
symlink reading not following.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-10-14 11:16:47 +02:00
Linus Torvalds 101105b171 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull more vfs updates from Al Viro:
 ">rename2() work from Miklos + current_time() from Deepa"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  fs: Replace current_fs_time() with current_time()
  fs: Replace CURRENT_TIME_SEC with current_time() for inode timestamps
  fs: Replace CURRENT_TIME with current_time() for inode timestamps
  fs: proc: Delete inode time initializations in proc_alloc_inode()
  vfs: Add current_time() api
  vfs: add note about i_op->rename changes to porting
  fs: rename "rename2" i_op to "rename"
  vfs: remove unused i_op->rename
  fs: make remaining filesystems use .rename2
  libfs: support RENAME_NOREPLACE in simple_rename()
  fs: support RENAME_NOREPLACE for local filesystems
  ncpfs: fix unused variable warning
2016-10-10 20:16:43 -07:00
Miklos Szeredi 2773bf00ae fs: rename "rename2" i_op to "rename"
Generated patch:

sed -i "s/\.rename2\t/\.rename\t\t/" `git grep -wl rename2`
sed -i "s/\brename2\b/rename/g" `git grep -wl rename2`

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-09-27 11:03:58 +02:00
Miklos Szeredi 18fc84dafa vfs: remove unused i_op->rename
No in-tree uses remain.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-09-27 11:03:58 +02:00
Miklos Szeredi 598e3c8f72 vfs: update ovl inode before relatime check
On overlayfs relatime_need_update() needs inode times to be correct on
overlay inode.  But i_mtime and i_ctime are updated by filesystem code on
underlying inode only, so they will be out-of-date on the overlay inode.

This patch copies the times from the underlying inode if needed.  This
can't be done if called from RCU lookup (link following) but link m/ctime
are not updated by fs, so this is all right.

This patch doesn't change functionality for anything but overlayfs.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-09-16 12:44:20 +02:00
Eryu Guan 337684a174 fs: return EPERM on immutable inode
In most cases, EPERM is returned on immutable inode, and there're only a
few places returning EACCES. I noticed this when running LTP on
overlayfs, setxattr03 failed due to unexpected EACCES on immutable
inode.

So converting all EACCES to EPERM on immutable inode.

Acked-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-08-07 10:03:31 -04:00
Linus Torvalds a867d7349e Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull userns vfs updates from Eric Biederman:
 "This tree contains some very long awaited work on generalizing the
  user namespace support for mounting filesystems to include filesystems
  with a backing store.  The real world target is fuse but the goal is
  to update the vfs to allow any filesystem to be supported.  This
  patchset is based on a lot of code review and testing to approach that
  goal.

  While looking at what is needed to support the fuse filesystem it
  became clear that there were things like xattrs for security modules
  that needed special treatment.  That the resolution of those concerns
  would not be fuse specific.  That sorting out these general issues
  made most sense at the generic level, where the right people could be
  drawn into the conversation, and the issues could be solved for
  everyone.

  At a high level what this patchset does a couple of simple things:

   - Add a user namespace owner (s_user_ns) to struct super_block.

   - Teach the vfs to handle filesystem uids and gids not mapping into
     to kuids and kgids and being reported as INVALID_UID and
     INVALID_GID in vfs data structures.

  By assigning a user namespace owner filesystems that are mounted with
  only user namespace privilege can be detected.  This allows security
  modules and the like to know which mounts may not be trusted.  This
  also allows the set of uids and gids that are communicated to the
  filesystem to be capped at the set of kuids and kgids that are in the
  owning user namespace of the filesystem.

  One of the crazier corner casees this handles is the case of inodes
  whose i_uid or i_gid are not mapped into the vfs.  Most of the code
  simply doesn't care but it is easy to confuse the inode writeback path
  so no operation that could cause an inode write-back is permitted for
  such inodes (aka only reads are allowed).

  This set of changes starts out by cleaning up the code paths involved
  in user namespace permirted mounts.  Then when things are clean enough
  adds code that cleanly sets s_user_ns.  Then additional restrictions
  are added that are possible now that the filesystem superblock
  contains owner information.

  These changes should not affect anyone in practice, but there are some
  parts of these restrictions that are changes in behavior.

   - Andy's restriction on suid executables that does not honor the
     suid bit when the path is from another mount namespace (think
     /proc/[pid]/fd/) or when the filesystem was mounted by a less
     privileged user.

   - The replacement of the user namespace implicit setting of MNT_NODEV
     with implicitly setting SB_I_NODEV on the filesystem superblock
     instead.

     Using SB_I_NODEV is a stronger form that happens to make this state
     user invisible.  The user visibility can be managed but it caused
     problems when it was introduced from applications reasonably
     expecting mount flags to be what they were set to.

  There is a little bit of work remaining before it is safe to support
  mounting filesystems with backing store in user namespaces, beyond
  what is in this set of changes.

   - Verifying the mounter has permission to read/write the block device
     during mount.

   - Teaching the integrity modules IMA and EVM to handle filesystems
     mounted with only user namespace root and to reduce trust in their
     security xattrs accordingly.

   - Capturing the mounters credentials and using that for permission
     checks in d_automount and the like.  (Given that overlayfs already
     does this, and we need the work in d_automount it make sense to
     generalize this case).

  Furthermore there are a few changes that are on the wishlist:

   - Get all filesystems supporting posix acls using the generic posix
     acls so that posix_acl_fix_xattr_from_user and
     posix_acl_fix_xattr_to_user may be removed.  [Maintainability]

   - Reducing the permission checks in places such as remount to allow
     the superblock owner to perform them.

   - Allowing the superblock owner to chown files with unmapped uids and
     gids to something that is mapped so the files may be treated
     normally.

  I am not considering even obvious relaxations of permission checks
  until it is clear there are no more corner cases that need to be
  locked down and handled generically.

  Many thanks to Seth Forshee who kept this code alive, and putting up
  with me rewriting substantial portions of what he did to handle more
  corner cases, and for his diligent testing and reviewing of my
  changes"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (30 commits)
  fs: Call d_automount with the filesystems creds
  fs: Update i_[ug]id_(read|write) to translate relative to s_user_ns
  evm: Translate user/group ids relative to s_user_ns when computing HMAC
  dquot: For now explicitly don't support filesystems outside of init_user_ns
  quota: Handle quota data stored in s_user_ns in quota_setxquota
  quota: Ensure qids map to the filesystem
  vfs: Don't create inodes with a uid or gid unknown to the vfs
  vfs: Don't modify inodes with a uid or gid unknown to the vfs
  cred: Reject inodes with invalid ids in set_create_file_as()
  fs: Check for invalid i_uid in may_follow_link()
  vfs: Verify acls are valid within superblock's s_user_ns.
  userns: Handle -1 in k[ug]id_has_mapping when !CONFIG_USER_NS
  fs: Refuse uid/gid changes which don't map into s_user_ns
  selinux: Add support for unprivileged mounts from user namespaces
  Smack: Handle labels consistently in untrusted mounts
  Smack: Add support for unprivileged mounts from user namespaces
  fs: Treat foreign mounts as nosuid
  fs: Limit file caps to the user namespace of the super block
  userns: Remove the now unnecessary FS_USERNS_DEV_MOUNT flag
  userns: Remove implicit MNT_NODEV fragility.
  ...
2016-07-29 15:54:19 -07:00
Linus Torvalds 20d00ee829 Revert "vfs: add lookup_hash() helper"
This reverts commit 3c9fe8cdff.

As Miklos points out in commit c1b2cc1a76, the "lookup_hash()" helper
is now unused, and in fact, with the hash salting changes, since the
hash of a dentry name now depends on the directory dentry it is in, the
helper function isn't even really likely to be useful.

So rather than keep it around in case somebody else might end up finding
a use for it, let's just remove the helper and not trick people into
thinking it might be a useful thing.

For example, I had obviously completely missed how the helper didn't
follow the normal dentry hashing patterns, and how the hash salting
patch broke overlayfs.  Things would quietly build and look sane, but
not work.

Suggested-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-29 12:17:52 -07:00
Linus Torvalds 6784725ab0 Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs updates from Al Viro:
 "Assorted cleanups and fixes.

  Probably the most interesting part long-term is ->d_init() - that will
  have a bunch of followups in (at least) ceph and lustre, but we'll
  need to sort the barrier-related rules before it can get used for
  really non-trivial stuff.

  Another fun thing is the merge of ->d_iput() callers (dentry_iput()
  and dentry_unlink_inode()) and a bunch of ->d_compare() ones (all
  except the one in __d_lookup_lru())"

* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (26 commits)
  fs/dcache.c: avoid soft-lockup in dput()
  vfs: new d_init method
  vfs: Update lookup_dcache() comment
  bdev: get rid of ->bd_inodes
  Remove last traces of ->sync_page
  new helper: d_same_name()
  dentry_cmp(): use lockless_dereference() instead of smp_read_barrier_depends()
  vfs: clean up documentation
  vfs: document ->d_real()
  vfs: merge .d_select_inode() into .d_real()
  unify dentry_iput() and dentry_unlink_inode()
  binfmt_misc: ->s_root is not going anywhere
  drop redundant ->owner initializations
  ufs: get rid of redundant checks
  orangefs: constify inode_operations
  missed comment updates from ->direct_IO() prototype change
  file_inode(f)->i_mapping is f->f_mapping
  trim fsnotify hooks a bit
  9p: new helper - v9fs_parent_fid()
  debugfs: ->d_parent is never NULL or negative
  ...
2016-07-28 12:59:05 -07:00
Oleg Drokin f4fdace947 vfs: Update lookup_dcache() comment
commit 6c51e513a3 ("lookup_dcache(): lift d_alloc() into callers")
removed the need_lookup argument from lookup_dcache(), but the
comment was forgotten. Also it no longer allocates a new dentry
if nothing was found.

Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-07-24 16:35:02 -04:00
Eric W. Biederman aeaa4a79ff fs: Call d_automount with the filesystems creds
Seth Forshee reported a mount regression in nfs autmounts
with "fs: Add user namespace member to struct super_block".

It turns out that the assumption that current->cred is something
reasonable during mount while necessary to improve support of
unprivileged mounts is wrong in the automount path.

To fix the existing filesystems override current->cred with the
init_cred before calling d_automount and restore current->cred after
d_automount completes.

To support unprivileged mounts would require a more nuanced cred
selection, so fail on unprivileged mounts for the time being.  As none
of the filesystems that currently set FS_USERNS_MOUNT implement
d_automount this check is only good for preventing future problems.

Fixes: 6e4eab577a ("fs: Add user namespace member to struct super_block")
Tested-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2016-07-23 14:51:26 -05:00
Eric W. Biederman 036d523641 vfs: Don't create inodes with a uid or gid unknown to the vfs
It is expected that filesystems can not represent uids and gids from
outside of their user namespace.  Keep things simple by not even
trying to create filesystem nodes with non-sense uids and gids.

Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2016-07-05 15:11:47 -05:00
Eric W. Biederman 0bd23d09b8 vfs: Don't modify inodes with a uid or gid unknown to the vfs
When a filesystem outside of init_user_ns is mounted it could have
uids and gids stored in it that do not map to init_user_ns.

The plan is to allow those filesystems to set i_uid to INVALID_UID and
i_gid to INVALID_GID for unmapped uids and gids and then to handle
that strange case in the vfs to ensure there is consistent robust
handling of the weirdness.

Upon a careful review of the vfs and filesystems about the only case
where there is any possibility of confusion or trouble is when the
inode is written back to disk.  In that case filesystems typically
read the inode->i_uid and inode->i_gid and write them to disk even
when just an inode timestamp is being updated.

Which leads to a rule that is very simple to implement and understand
inodes whose i_uid or i_gid is not valid may not be written.

In dealing with access times this means treat those inodes as if the
inode flag S_NOATIME was set.  Reads of the inodes appear safe and
useful, but any write or modification is disallowed.  The only inode
write that is allowed is a chown that sets the uid and gid on the
inode to valid values.  After such a chown the inode is normal and may
be treated as such.

Denying all writes to inodes with uids or gids unknown to the vfs also
prevents several oddball cases where corruption would have occurred
because the vfs does not have complete information.

One problem case that is prevented is attempting to use the gid of a
directory for new inodes where the directories sgid bit is set but the
directories gid is not mapped.

Another problem case avoided is attempting to update the evm hash
after setxattr, removexattr, and setattr.  As the evm hash includeds
the inode->i_uid or inode->i_gid not knowning the uid or gid prevents
a correct evm hash from being computed.  evm hash verification also
fails when i_uid or i_gid is unknown but that is essentially harmless
as it does not cause filesystem corruption.

Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2016-07-05 15:06:46 -05:00
Seth Forshee 2d7f9e2ad3 fs: Check for invalid i_uid in may_follow_link()
Filesystem uids which don't map into a user namespace may result
in inode->i_uid being INVALID_UID. A symlink and its parent
could have different owners in the filesystem can both get
mapped to INVALID_UID, which may result in following a symlink
when this would not have otherwise been permitted when protected
symlinks are enabled.

Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2016-06-30 18:05:09 -05:00
Miklos Szeredi 2d902671ce vfs: merge .d_select_inode() into .d_real()
The two methods essentially do the same: find the real dentry/inode
belonging to an overlay dentry.  The difference is in the usage:

vfs_open() uses ->d_select_inode() and expects the function to perform
copy-up if necessary based on the open flags argument.

file_dentry() uses ->d_real() passing in the overlay dentry as well as the
underlying inode.

vfs_rename() uses ->d_select_inode() but passes zero flags.  ->d_real()
with a zero inode would have worked just as well here.

This patch merges the functionality of ->d_select_inode() into ->d_real()
by adding an 'open_flags' argument to the latter.

[Al Viro] Make the signature of d_real() match that of ->d_real() again.
And constify the inode argument, while we are at it.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2016-06-30 08:53:27 +02:00
Eric W. Biederman a2982cc922 vfs: Generalize filesystem nodev handling.
Introduce a function may_open_dev that tests MNT_NODEV and a new
superblock flab SB_I_NODEV.  Use this new function in all of the
places where MNT_NODEV was previously tested.

Add the new SB_I_NODEV s_iflag to proc, sysfs, and mqueuefs as those
filesystems should never support device nodes, and a simple superblock
flags makes that very hard to get wrong.  With SB_I_NODEV set if any
device nodes somehow manage to show up on on a filesystem those
device nodes will be unopenable.

Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2016-06-23 15:41:57 -05:00
Linus Torvalds 8387ff2577 vfs: make the string hashes salt the hash
We always mixed in the parent pointer into the dentry name hash, but we
did it late at lookup time.  It turns out that we can simplify that
lookup-time action by salting the hash with the parent pointer early
instead of late.

A few other users of our string hashes also wanted to mix in their own
pointers into the hash, and those are updated to use the same mechanism.

Hash users that don't have any particular initial salt can just use the
NULL pointer as a no-salt.

Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: George Spelvin <linux@sciencehorizons.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-10 20:21:46 -07:00
Linus Torvalds c8ae067f26 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs fixes from Al Viro:
 "Fixes for crap of assorted ages: EOPENSTALE one is 4.2+, autofs one is
  4.6, d_walk - 3.2+.

  The atomic_open() and coredump ones are regressions from this window"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  coredump: fix dumping through pipes
  fix a regression in atomic_open()
  fix d_walk()/non-delayed __d_free() race
  autofs braino fix for do_last()
  fix EOPENSTALE bug in do_last()
2016-06-07 20:41:36 -07:00
Al Viro a01e718f72 fix a regression in atomic_open()
open("/foo/no_such_file", O_RDONLY | O_CREAT) on should fail with
EACCES when /foo is not writable; failing with ENOENT is obviously
wrong.  That got broken by a braino introduced when moving the
creat_error logics from atomic_open() to lookup_open().  Easy to
fix, fortunately.

Spotted-by: "Yan, Zheng" <ukernel@gmail.com>
Tested-by: "Yan, Zheng" <ukernel@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-06-07 21:53:51 -04:00
Eric W. Biederman eedf265aa0 devpts: Make each mount of devpts an independent filesystem.
The /dev/ptmx device node is changed to lookup the directory entry "pts"
in the same directory as the /dev/ptmx device node was opened in.  If
there is a "pts" entry and that entry is a devpts filesystem /dev/ptmx
uses that filesystem.  Otherwise the open of /dev/ptmx fails.

The DEVPTS_MULTIPLE_INSTANCES configuration option is removed, so that
userspace can now safely depend on each mount of devpts creating a new
instance of the filesystem.

Each mount of devpts is now a separate and equal filesystem.

Reserved ttys are now available to all instances of devpts where the
mounter is in the initial mount namespace.

A new vfs helper path_pts is introduced that finds a directory entry
named "pts" in the directory of the passed in path, and changes the
passed in path to point to it.  The helper path_pts uses a function
path_parent_directory that was factored out of follow_dotdot.

In the implementation of devpts:
 - devpts_mnt is killed as it is no longer meaningful if all mounts of
   devpts are equal.
 - pts_sb_from_inode is replaced by just inode->i_sb as all cached
   inodes in the tty layer are now from the devpts filesystem.
 - devpts_add_ref is rolled into the new function devpts_ptmx.  And the
   unnecessary inode hold is removed.
 - devpts_del_ref is renamed devpts_release and reduced to just a
   deacrivate_super.
 - The newinstance mount option continues to be accepted but is now
   ignored.

In devpts_fs.h definitions for when !CONFIG_UNIX98_PTYS are removed as
they are never used.

Documentation/filesystems/devices.txt is updated to describe the current
situation.

This has been verified to work properly on openwrt-15.05, centos5,
centos6, centos7, debian-6.0.2, debian-7.9, debian-8.2, ubuntu-14.04.3,
ubuntu-15.10, fedora23, magia-5, mint-17.3, opensuse-42.1,
slackware-14.1, gentoo-20151225 (13.0?), archlinux-2015-12-01.  With the
caveat that on centos6 and on slackware-14.1 that there wind up being
two instances of the devpts filesystem mounted on /dev/pts, the lower
copy does not end up getting used.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Greg KH <greg@kroah.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Peter Anvin <hpa@zytor.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Serge Hallyn <serge.hallyn@ubuntu.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: Jann Horn <jann@thejh.net>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Florian Weimer <fw@deneb.enyo.de>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-05 10:36:01 -07:00
Al Viro e6ec03a25f autofs braino fix for do_last()
It's an analogue of commit 7500c38a (fix the braino in "namei:
massage lookup_slow() to be usable by lookup_one_len_unlocked()").
The same problem (->lookup()-returned unhashed negative dentry
just might be an autofs one with ->d_manage() that would wait
until the daemon makes it positive) applies in do_last() - we
need to do follow_managed() first.

Fortunately, remaining callers of follow_managed() are OK - only
autofs has that weirdness (negative dentry that does not mean
an instant -ENOENT)) and autofs never has its negative dentries
hashed, so we can't pick one from a dcache lookup.

->d_manage() is a bloody mess ;-/

Cc: stable@vger.kernel.org # v4.6
Spotted-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-06-05 00:23:09 -04:00
Al Viro fac7d1917d fix EOPENSTALE bug in do_last()
EOPENSTALE occuring at the last component of a trailing symlink ends up
with do_last() retrying its lookup.  After the symlink body has been
discarded.  The thing is, all this retry_lookup logics in there is not
needed at all - the upper layers will do the right thing if we simply
return that -EOPENSTALE as we would with any other error.  Trying to
microoptimize in do_last() is a lot of headache for no good reason.

Cc: stable@vger.kernel.org # v4.2+
Tested-by: Oleg Drokin <green@linuxhacker.ru>
Reviewed-and-Tested-by: Jeff Layton <jlayton@poochiereds.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-06-04 11:59:04 -04:00