linux.git/fs/overlayfs/export.c, branch v5.5

ovl: make sure that real fid is 32bit aligned in memory

2019-12-10T15:00:55+00:00

Seprate on-disk encoding from in-memory and on-wire resresentation
of overlay file handle.

In-memory and on-wire we only ever pass around pointers to struct
ovl_fh, which encapsulates at offset 3 the on-disk format struct
ovl_fb. struct ovl_fb encapsulates at offset 21 the real file handle.
That makes sure that the real file handle is always 32bit aligned
in-memory when passed down to the underlying filesystem.

On-disk format remains the same and store/load are done into
correctly aligned buffer.

New nfs exported file handles are exported with aligned real fid.
Old nfs file handles are copied to an aligned buffer before being
decoded.

Reported-by: Al Viro 
Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: Fix dereferencing possible ERR_PTR()

2019-09-11T14:11:45+00:00

if ovl_encode_real_fh() fails, no memory was allocated
and the error in the error-valued pointer should be returned.

Fixes: 9b6faee07470 ("ovl: check ERR_PTR() return value from ovl_encode_fh()")
Signed-off-by: Ding Xiang 
Cc:  # v4.16+
Signed-off-by: Miklos Szeredi

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

2019-06-19T15:09:55+00:00

Based on 2 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Enrico Weigelt 
Reviewed-by: Kate Stewart 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman

ovl_lookup_real_one(): don't bother with strlen()

2019-04-26T17:13:33+00:00

Signed-off-by: Al Viro

ovl: fix decode of dir file handle with multi lower layers

2018-11-21T09:44:48+00:00

When decoding a lower file handle, we first call ovl_check_origin_fh()
with connected=false to get any real lower dentry for overlay inode
cache lookup.

If the real dentry is a disconnected dir dentry, ovl_check_origin_fh()
is called again with connected=true to get a connected real dentry
and find the lower layer the real dentry belongs to.

If the first call returned a connected real dentry, we use it to
lookup an overlay connected dentry, but the first ovl_check_origin_fh()
call with connected=false did not check that the found dentry is under
the root of the layer (see ovl_acceptable()), it only checked that
the found dentry super block matches the uuid of the lower file handle.

In case there are multiple lower layers on the same fs and the found
dentry is not from the top most lower layer, using the layer index
returned from the first ovl_check_origin_fh() is wrong and we end
up failing to decode the file handle.

Fix this by always calling ovl_check_origin_fh() with connected=true
if we got a directory dentry in the first call.

Fixes: 8b58924ad55c ("ovl: lookup in inode cache first when decoding...")
Cc:  # v4.17
Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: Modify ovl_lookup() and friends to lookup metacopy dentry

2018-07-20T07:56:09+00:00

This patch modifies ovl_lookup() and friends to lookup metacopy dentries.
It also allows for presence of metacopy dentries in lower layer.

During lookup, check for presence of OVL_XATTR_METACOPY and if not present,
set OVL_UPPERDATA bit in flags.

We don't support metacopy feature with nfs_export.  So in nfs_export code,
we set OVL_UPPERDATA flag set unconditionally if upper inode exists.

Do not follow metacopy origin if we find a metacopy only inode and metacopy
feature is not enabled for that mount.  Like redirect, this can have
security implications where an attacker could hand craft upper and try to
gain access to file on lower which it should not have to begin with.

Signed-off-by: Vivek Goyal 
Reviewed-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: Pass argument to ovl_get_inode() in a structure

2018-05-31T09:06:12+00:00

ovl_get_inode() right now has 5 parameters. Soon this patch series will
add 2 more and suddenly argument list starts looking too long.

Hence pass arguments to ovl_get_inode() in a structure and it looks
little cleaner.

Signed-off-by: Vivek Goyal 
Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: consistent i_ino for non-samefs with xino

2018-04-12T10:04:50+00:00

When overlay layers are not all on the same fs, but all inode numbers
of underlying fs do not use the high 'xino' bits, overlay st_ino values
are constant and persistent.

In that case, set i_ino value to the same value as st_ino for nfsd
readdirplus validator.

Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: cleanup setting OVL_INDEX

2018-04-12T10:04:49+00:00

Signed-off-by: Miklos Szeredi

ovl: lookup in inode cache first when decoding lower file handle

2018-04-12T10:04:49+00:00

When decoding a lower file handle, we need to check if lower file was
copied up and indexed and if it has a whiteout index, we need to check
if this is an unlinked but open non-dir before returning -ESTALE.

To find out if this is an unlinked but open non-dir we need to lookup
an overlay inode in inode cache by lower inode and that requires decoding
the lower file handle before looking in inode cache.

Before this change, if the lower inode turned out to be a directory, we
may have paid an expensive cost to reconnect that lower directory for
nothing.

After this change, we start by decoding a disconnected lower dentry and
using the lower inode for looking up an overlay inode in inode cache.
If we find overlay inode and dentry in cache, we avoid the index lookup
overhead. If we don't find an overlay inode and dentry in cache, then we
only need to decode a connected lower dentry in case the lower dentry is
a non-indexed directory.

The xfstests group overlay/exportfs tests decoding overlayfs file
handles after drop_caches with different states of the file at encode
and decode time. Overall the tests in the group call ovl_lower_fh_to_d()
89 times to decode a lower file handle.

Before this change, the tests called ovl_get_index_fh() 75 times and
reconnect_one() 61 times.
After this change, the tests call ovl_get_index_fh() 70 times and
reconnect_one() 59 times. The 2 cases where reconnect_one() was avoided
are cases where a non-upper directory file handle was encoded, then the
directory removed and then file handle was decoded.

To demonstrate the affect on decoding file handles with hot inode/dentry
cache, the drop_caches call in the tests was disabled. Without
drop_caches, there are no reconnect_one() calls at all before or after
the change. Before the change, there are 75 calls to ovl_get_index_fh(),
exactly as the case with drop_caches. After the change, there are only
10 calls to ovl_get_index_fh().

Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi