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  1. 29 Jul, 2016 17 commits
    • Vivek Goyal's avatar
      ovl: append MAY_READ when diluting write checks · 500cac3c
      Vivek Goyal authored 
      Right now we remove MAY_WRITE/MAY_APPEND bits from mask if realfile is on
lower/. This is done as files on lower will never be written and will be
copied up. But to copy up a file, mounter should have MAY_READ permission
otherwise copy up will fail. So set MAY_READ in mask when MAY_WRITE is
reset.

Dan Walsh noticed this when he did access(lowerfile, W_OK) and it returned
True (context mounts) but when he tried to actually write to file, it
failed as mounter did not have permission on lower file.

[SzM] don't set MAY_READ if only MAY_APPEND is set without MAY_WRITE; this
won't trigger a copy-up.
Reported-by: default avatarDan Walsh <dwalsh@redhat.com>
Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      500cac3c
    • Vivek Goyal's avatar
      ovl: dilute permission checks on lower only if not special file · e29841a0
      Vivek Goyal authored 
      Right now if file is on lower/, we remove MAY_WRITE/MAY_APPEND bits from
mask as lower/ will never be written and file will be copied up. But this
is not true for special files. These files are not copied up and are opened
in place. So don't dilute the checks for these types of files.
Reported-by: default avatarDan Walsh <dwalsh@redhat.com>
Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      e29841a0
    • Miklos Szeredi's avatar
      ovl: fix POSIX ACL setting · d837a49b
      Miklos Szeredi authored 
      Setting POSIX ACL needs special handling:

1) Some permission checks are done by ->setxattr() which now uses mounter's
creds ("ovl: do operations on underlying file system in mounter's
context").  These permission checks need to be done with current cred as
well.

2) Setting ACL can fail for various reasons.  We do not need to copy up in
these cases.

In the mean time switch to using generic_setxattr.

[Arnd Bergmann] Fix link error without POSIX ACL. posix_acl_from_xattr()
doesn't have a 'static inline' implementation when CONFIG_FS_POSIX_ACL is
disabled, and I could not come up with an obvious way to do it.

This instead avoids the link error by defining two sets of ACL operations
and letting the compiler drop one of the two at compile time depending
on CONFIG_FS_POSIX_ACL. This avoids all references to the ACL code,
also leading to smaller code.
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      d837a49b
    • Miklos Szeredi's avatar
      ovl: share inode for hard link · 51f7e52d
      Miklos Szeredi authored 
      Inode attributes are copied up to overlay inode (uid, gid, mode, atime,
mtime, ctime) so generic code using these fields works correcty.  If a hard
link is created in overlayfs separate inodes are allocated for each link.
If chmod/chown/etc. is performed on one of the links then the inode
belonging to the other ones won't be updated.

This patch attempts to fix this by sharing inodes for hard links.

Use inode hash (with real inode pointer as a key) to make sure overlay
inodes are shared for hard links on upper.  Hard links on lower are still
split (which is not user observable until the copy-up happens, see
Documentation/filesystems/overlayfs.txt under "Non-standard behavior").

The inode is only inserted in the hash if it is non-directoy and upper.
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      51f7e52d
    • Miklos Szeredi's avatar
      ovl: store real inode pointer in ->i_private · 39b681f8
      Miklos Szeredi authored 
      To get from overlay inode to real inode we currently use 'struct
ovl_entry', which has lifetime connected to overlay dentry.  This is okay,
since each overlay dentry had a new overlay inode allocated.

Following patch will break that assumption, so need to leave out ovl_entry.
This patch stores the real inode directly in i_private, with the lowest bit
used to indicate whether the inode is upper or lower.

Lifetime rules remain, using ovl_inode_real() must only be done while
caller holds ref on overlay dentry (and hence on real dentry), or within
RCU protected regions.
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      39b681f8
    • Miklos Szeredi's avatar
      ovl: permission: return ECHILD instead of ENOENT · a999d7e1
      Miklos Szeredi authored 
      The error is due to RCU and is temporary.
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      a999d7e1
    • Miklos Szeredi's avatar
      ovl: update atime on upper · d719e8f2
      Miklos Szeredi authored 
      Fix atime update logic in overlayfs.

This patch adds an i_op->update_time() handler to overlayfs inodes.  This
forwards atime updates to the upper layer only.  No atime updates are done
on lower layers.

Remove implicit atime updates to underlying files and directories with
O_NOATIME.  Remove explicit atime update in ovl_readlink().

Clear atime related mnt flags from cloned upper mount.  This means atime
updates are controlled purely by overlayfs mount options.

Reported-by: Konstantin Khlebnikov <koct9i@gmail.com> 
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      d719e8f2
    • Miklos Szeredi's avatar
      ovl: fix sgid on directory · bb0d2b8a
      Miklos Szeredi authored 
      When creating directory in workdir, the group/sgid inheritance from the
parent dir was omitted completely.  Fix this by calling inode_init_owner()
on overlay inode and using the resulting uid/gid/mode to create the file.

Unfortunately the sgid bit can be stripped off due to umask, so need to
reset the mode in this case in workdir before moving the directory in
place.
Reported-by: default avatarEryu Guan <eguan@redhat.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      bb0d2b8a
    • Miklos Szeredi's avatar
      ovl: simplify permission checking · 9c630ebe
      Miklos Szeredi authored 
      The fact that we always do permission checking on the overlay inode and
clear MAY_WRITE for checking access to the lower inode allows cruft to be
removed from ovl_permission().

1) "default_permissions" option effectively did generic_permission() on the
overlay inode with i_mode, i_uid and i_gid updated from underlying
filesystem.  This is what we do by default now.  It did the update using
vfs_getattr() but that's only needed if the underlying filesystem can
change (which is not allowed).  We may later introduce a "paranoia_mode"
that verifies that mode/uid/gid are not changed.

2) splitting out the IS_RDONLY() check from inode_permission() also becomes
unnecessary once we remove the MAY_WRITE from the lower inode check.
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      9c630ebe
    • Vivek Goyal's avatar
      ovl: do not require mounter to have MAY_WRITE on lower · 754f8cb7
      Vivek Goyal authored 
      Now we have two levels of checks in ovl_permission(). overlay inode
is checked with the creds of task while underlying inode is checked
with the creds of mounter.

Looks like mounter does not have to have WRITE access to files on lower/.
So remove the MAY_WRITE from access mask for checks on underlying
lower inode.

This means task should still have the MAY_WRITE permission on lower
inode and mounter is not required to have MAY_WRITE.

It also solves the problem of read only NFS mounts being used as lower.
If __inode_permission(lower_inode, MAY_WRITE) is called on read only
NFS, it fails. By resetting MAY_WRITE, check succeeds and case of
read only NFS shold work with overlay without having to specify any
special mount options (default permission).
Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      754f8cb7
    • Vivek Goyal's avatar
      ovl: do operations on underlying file system in mounter's context · 1175b6b8
      Vivek Goyal authored 
      Given we are now doing checks both on overlay inode as well underlying
inode, we should be able to do checks and operations on underlying file
system using mounter's context.

So modify all operations to do checks/operations on underlying dentry/inode
in the context of mounter.
Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      1175b6b8
    • Vivek Goyal's avatar
      ovl: modify ovl_permission() to do checks on two inodes · c0ca3d70
      Vivek Goyal authored 
      Right now ovl_permission() calls __inode_permission(realinode), to do
permission checks on real inode and no checks are done on overlay inode.

Modify it to do checks both on overlay inode as well as underlying inode.
Checks on overlay inode will be done with the creds of calling task while
checks on underlying inode will be done with the creds of mounter.
Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      c0ca3d70
    • Vivek Goyal's avatar
      ovl: define ->get_acl() for overlay inodes · 39a25b2b
      Vivek Goyal authored 
      Now we are planning to do DAC permission checks on overlay inode
itself. And to make it work, we will need to make sure we can get acls from
underlying inode. So define ->get_acl() for overlay inodes and this in turn
calls into underlying filesystem to get acls, if any.
Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      39a25b2b
    • Vivek Goyal's avatar
      ovl: move some common code in a function · 72e48481
      Vivek Goyal authored 
      ovl_create_upper() and ovl_create_over_whiteout() seem to be sharing some
common code which can be moved into a separate function.  No functionality
change.
Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      72e48481
    • Andreas Gruenbacher's avatar
      ovl: store ovl_entry in inode->i_private for all inodes · 58ed4e70
      Andreas Gruenbacher authored 
      Previously this was only done for directory inodes.  Doing so for all
inodes makes for a nice cleanup in ovl_permission at zero cost.

Inodes are not shared for hard links on the overlay, so this works fine.
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      58ed4e70
    • Miklos Szeredi's avatar
      ovl: use generic_delete_inode · eead4f2d
      Miklos Szeredi authored 
      No point in keeping overlay inodes around since they will never be reused.
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
      eead4f2d
    • Miklos Szeredi's avatar
      ovl: check mounter creds on underlying lookup · c1b2cc1a
      Miklos Szeredi authored 
      The hash salting changes meant that we can no longer reuse the hash in the
overlay dentry to look up the underlying dentry.

Instead of lookup_hash(), use lookup_one_len_unlocked() and swith to
mounter's creds (like we do for all other operations later in the series).

Now the lookup_hash() export introduced in 4.6 by 3c9fe8cd ("vfs: add
lookup_hash() helper") is unused and can possibly be removed; its
usefulness negated by the hash salting and the idea that mounter's creds
should be used on operations on underlying filesystems.
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
Fixes: 8387ff25 ("vfs: make the string hashes salt the hash")
      c1b2cc1a
  3. 27 Jul, 2016 1 commit
  5. 24 Jul, 2016 2 commits
  7. 23 Jul, 2016 20 commits
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