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Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Richard Weinberger <richard@nod.at>
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The conflict was an interaction between a bug fix in the
netvsc driver in 'net' and an optimization of the RX path
in 'net-next'.
Signed-off-by: David S. Miller <davem@davemloft.net>
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Commit 6326fec1122c ("mm: Use owner_priv bit for PageSwapCache, valid
when PageSwapBacked") aliased PG_swapcache to PG_owner_priv_1 (and
depending on PageSwapBacked being true).
As a result, the KPF_SWAPCACHE bit in '/proc/kpageflags' should now be
synthesized, instead of being shown on unrelated pages which just happen
to have PG_owner_priv_1 set.
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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If overlay was mounted by root then quota set for upper layer does not work
because overlay now always use mounter's credentials for operations.
Also overlay might deplete reserved space and inodes in ext4.
This patch drops capability SYS_RESOURCE from saved credentials.
This affects creation new files, whiteouts, and copy-up operations.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Fixes: 1175b6b8d963 ("ovl: do operations on underlying file system in mounter's context")
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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overlayfs syncs all inode pages on sync_filesystem(), but it also
needs to call s_op->sync_fs() of upper fs for metadata sync.
This fixes correctness of syncfs(2) as demonstrated by following
xfs specific test:
xfs_sync_stats()
{
echo $1
echo -n "xfs_log_force = "
grep log /proc/fs/xfs/stat | awk '{ print $5 }'
}
xfs_sync_stats "before touch"
touch x
xfs_sync_stats "after touch"
xfs_io -c syncfs .
xfs_sync_stats "after syncfs"
xfs_io -c fsync x
xfs_sync_stats "after fsync"
xfs_io -c fsync x
xfs_sync_stats "after fsync #2"
When this test is run in overlay mount over xfs, log force
count does not increase with syncfs command.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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Now that copy up of regular file is done using O_TMPFILE,
we don't need to hold rename_lock throughout copy up.
Use the copy up waitqueue to synchronize concurrent copy up
of the same file. Different regular files can be copied up
concurrently.
The upper dir inode_lock is taken instead of rename_lock,
because it is needed for lookup and later for linking the
temp file, but it is released while copying up data.
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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The overlay sb 'copyup_wq' and overlay inode 'copying' condition
variable are about to replace the upper sb rename_lock, as finer
grained synchronization objects for concurrent copy up.
Suggested-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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In preparation for concurrent copy up, implement copy up
of regular file as O_TMPFILE that is linked to upperdir
instead of a file in workdir that is moved to upperdir.
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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As preparation to implementing copy up with O_TMPFILE,
name the variable for dentry before final rename 'temp' and
assign it to 'newdentry' only after rename.
Also lookup upper dentry before looking up temp dentry and
move ovl_set_timestamps() into ovl_copy_up_locked(), because
that is going to be more convenient for upcoming change.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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This is needed for choosing between concurrent copyup
using O_TMPFILE and legacy copyup using workdir+rename.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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Before calling write f_ops, call file_start_write() instead
of sb_start_write().
Replace {sb,file}_start_write() for {copy,clone}_file_range() and
for fallocate().
Beyond correct semantics, this avoids freeze protection to sb when
operating on special inodes, such as fallocate() on a blockdev.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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There is no in-tree file system that implements copy_file_range()
for non regular files.
Deny an attempt to copy_file_range() a directory with EISDIR
and any other non regualr file with EINVAL to conform with
behavior of vfs_{clone,dedup}_file_range().
This change is needed prior to converting sb_start_write()
to file_start_write() in the vfs helper.
Cc: linux-api@vger.kernel.org
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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There was an obscure use case of fallocate of directory inode
in the vfs helper with the comment:
"Let individual file system decide if it supports preallocation
for directories or not."
But there is no in-tree file system that implements fallocate
for directory operations.
Deny an attempt to fallocate a directory with EISDIR error.
This change is needed prior to converting sb_start_write()
to file_start_write(), so freeze protection is correctly
handled for cases of fallocate file and blockdev.
Cc: linux-api@vger.kernel.org
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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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>
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When a completion is declared on-stack we have to use
COMPLETION_INITIALIZER_ONSTACK().
Fixes: 0b81d07790726 ("fs crypto: move per-file encryption from f2fs
tree to fs/crypto")
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Previously, each filesystem configured without encryption support would
define all the public fscrypt functions to their notsupp_* stubs. This
list of #defines had to be updated in every filesystem whenever a change
was made to the public fscrypt functions. To make things more
maintainable now that we have three filesystems using fscrypt, split the
old header fscrypto.h into several new headers. fscrypt_supp.h contains
the real declarations and is included by filesystems when configured
with encryption support, whereas fscrypt_notsupp.h contains the inline
stubs and is included by filesystems when configured without encryption
support. fscrypt_common.h contains common declarations needed by both.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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res is assigned to sizeof(ctx), however, this is unused and res
is updated later on without that assigned value to res ever being
used. Remove this redundant assignment.
Fixes CoverityScan CID#1395546 "Unused value"
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Instead of preallocating all the required COW blocks in the high-level
write code do it inside the iomap code, like we do for all other I/O.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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When we allocate COW fork blocks for direct I/O writes we currently first
create a delayed allocation, and then convert it to a real allocation
once we've got the delayed one.
As there is no good reason for that this patch instead makes use call
xfs_bmapi_write from the COW allocation path. The only interesting bits
are a few tweaks the low-level allocator to allow for this, most notably
the need to remove the call to xfs_bmap_extsize_align for the cowextsize
in xfs_bmap_btalloc - for the existing convert case it's a no-op, but
for the direct allocation case it would blow up our block reservation
way beyond what we reserved for the transaction.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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We'll need it for the direct I/O code. Also rename the function to
xfs_reflink_convert_cow_extent to describe it a bit better.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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Factor a helper to calculate the extent-size aligned block out of the
iomap code, so that it can be reused by the upcoming reflink dio code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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We currently fall back from direct to buffered writes if we detect a
remaining shared extent in the iomap_begin callback. But by the time
iomap_begin is called for the potentially unaligned end block we might
have already written most of the data to disk, which we'd now write
again using buffered I/O. To avoid this reject all writes to reflinked
files before starting I/O so that we are guaranteed to only write the
data once.
The alternative would be to unshare the unaligned start and/or end block
before doing the I/O. I think that's doable, and will actually be
required to support reflinks on DAX file system. But it will take a
little more time and I'd rather get rid of the double write ASAP.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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If you change the set of filesystems that are exported, then
the contents of various directories in the NFSv4 pseudo-root
is likely to change. However the change-id of those
directories is currently tied to the underlying directory,
so the client may not see the changes in a timely fashion.
This patch changes the change-id number to be derived from the
"flush_time" of the export cache. Whenever any changes are
made to the set of exported filesystems, this flush_time is
updated. The result is that clients see changes to the set
of exported filesystems much more quickly, often immediately.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
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This ioctl is modeled after the xfs's XFS_IOC_GOINGDOWN ioctl. (In
fact, it uses the same code points.)
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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Add a shutdown bit that will cause ext4 processing to fail immediately
with EIO.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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We are currently using one bit in s_resize_flags; rename it in order
to allow more of the bits in that unsigned long for other purposes.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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If the file system requires journal recovery, and the device is
read-ony, return EROFS to the mount system call. This allows xfstests
generic/050 to pass.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
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If the journal is aborted, the needs_recovery feature flag should not
be removed. Otherwise, it's the journal might not get replayed and
this could lead to more data getting lost.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
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If the journal has been aborted, we shouldn't mark the underlying
buffer head as dirty, since that will cause the metadata block to get
modified. And if the journal has been aborted, we shouldn't allow
this since it will almost certainly lead to a corrupted file system.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
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The write_end() function must always unlock the page and drop its ref
count, even on an error.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
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After successful IO or permanent error, b_first_retry_time also
needs to be cleared, else the invalid first retry time will be
used by the next retry check.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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Tetsuo has noticed that an OOM stress test which performs large write
requests can cause the full memory reserves depletion. He has tracked
this down to the following path
__alloc_pages_nodemask+0x436/0x4d0
alloc_pages_current+0x97/0x1b0
__page_cache_alloc+0x15d/0x1a0 mm/filemap.c:728
pagecache_get_page+0x5a/0x2b0 mm/filemap.c:1331
grab_cache_page_write_begin+0x23/0x40 mm/filemap.c:2773
iomap_write_begin+0x50/0xd0 fs/iomap.c:118
iomap_write_actor+0xb5/0x1a0 fs/iomap.c:190
? iomap_write_end+0x80/0x80 fs/iomap.c:150
iomap_apply+0xb3/0x130 fs/iomap.c:79
iomap_file_buffered_write+0x68/0xa0 fs/iomap.c:243
? iomap_write_end+0x80/0x80
xfs_file_buffered_aio_write+0x132/0x390 [xfs]
? remove_wait_queue+0x59/0x60
xfs_file_write_iter+0x90/0x130 [xfs]
__vfs_write+0xe5/0x140
vfs_write+0xc7/0x1f0
? syscall_trace_enter+0x1d0/0x380
SyS_write+0x58/0xc0
do_syscall_64+0x6c/0x200
entry_SYSCALL64_slow_path+0x25/0x25
the oom victim has access to all memory reserves to make a forward
progress to exit easier. But iomap_file_buffered_write and other
callers of iomap_apply loop to complete the full request. We need to
check for fatal signals and back off with a short write instead.
As the iomap_apply delegates all the work down to the actor we have to
hook into those. All callers that work with the page cache are calling
iomap_write_begin so we will check for signals there. dax_iomap_actor
has to handle the situation explicitly because it copies data to the
userspace directly. Other callers like iomap_page_mkwrite work on a
single page or iomap_fiemap_actor do not allocate memory based on the
given len.
Fixes: 68a9f5e7007c ("xfs: implement iomap based buffered write path")
Link: http://lkml.kernel.org/r/20170201092706.9966-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org> [4.8+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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It is not used anywhere.
CC: Mike Marshall <hubcap@omnibond.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>
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Signed-off-by: Martin Brandenburg <martin@omnibond.com>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>
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The issue here is that in orangefs_bufmap_alloc() we do:
bufmap->buffer_index_array =
kzalloc(DIV_ROUND_UP(bufmap->desc_count, BITS_PER_LONG), GFP_KERNEL);
If we choose a bufmap->desc_count like -31 then it means the
DIV_ROUND_UP ends up having an integer overflow. The result is that
kzalloc() returns the ZERO_SIZE_PTR and there is a static checker
warning.
But this bug is harmless because on the next lines we use ->desc_count
to do a kcalloc(). That has integer overflow checking built in so the
kcalloc() fails and we return an error code.
Anyway, it doesn't make sense to talk about negative sizes and blocking
them silences the static checker warning.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>
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"out" label was only returning error code.
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Jan Kara <jack@suse.cz>
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Currently, lsattr for instance in udf directory gives
"udf: Invalid argument While reading flags on ..."
This patch returns -ENOIOCTLCMD
when command is unknown to have more accurate message like this:
"Inappropriate ioctl for device While reading flags on ..."
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Jan Kara <jack@suse.cz>
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It only gets called from aops.c and doesn't appear in any headers.
Signed-off-by: Andrew Price <anprice@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
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Ever since mount propagation was introduced in cases where a mount in
propagated to parent mount mountpoint pair that is already in use the
code has placed the new mount behind the old mount in the mount hash
table.
This implementation detail is problematic as it allows creating
arbitrary length mount hash chains.
Furthermore it invalidates the constraint maintained elsewhere in the
mount code that a parent mount and a mountpoint pair will have exactly
one mount upon them. Making it hard to deal with and to talk about
this special case in the mount code.
Modify mount propagation to notice when there is already a mount at
the parent mount and mountpoint where a new mount is propagating to
and place that preexisting mount on top of the new mount.
Modify unmount propagation to notice when a mount that is being
unmounted has another mount on top of it (and no other children), and
to replace the unmounted mount with the mount on top of it.
Move the MNT_UMUONT test from __lookup_mnt_last into
__propagate_umount as that is the only call of __lookup_mnt_last where
MNT_UMOUNT may be set on any mount visible in the mount hash table.
These modifications allow:
- __lookup_mnt_last to be removed.
- attach_shadows to be renamed __attach_mnt and its shadow
handling to be removed.
- commit_tree to be simplified
- copy_tree to be simplified
The result is an easier to understand tree of mounts that does not
allow creation of arbitrary length hash chains in the mount hash table.
The result is also a very slight userspace visible difference in semantics.
The following two cases now behave identically, where before order
mattered:
case 1: (explicit user action)
B is a slave of A
mount something on A/a , it will propagate to B/a
and than mount something on B/a
case 2: (tucked mount)
B is a slave of A
mount something on B/a
and than mount something on A/a
Histroically umount A/a would fail in case 1 and succeed in case 2.
Now umount A/a succeeds in both configurations.
This very small change in semantics appears if anything to be a bug
fix to me and my survey of userspace leads me to believe that no programs
will notice or care of this subtle semantic change.
v2: Updated to mnt_change_mountpoint to not call dput or mntput
and instead to decrement the counts directly. It is guaranteed
that there will be other references when mnt_change_mountpoint is
called so this is safe.
v3: Moved put_mountpoint under mount_lock in attach_recursive_mnt
As the locking in fs/namespace.c changed between v2 and v3.
v4: Reworked the logic in propagate_mount_busy and __propagate_umount
that detects when a mount completely covers another mount.
v5: Removed unnecessary tests whose result is alwasy true in
find_topper and attach_recursive_mnt.
v6: Document the user space visible semantic difference.
Cc: stable@vger.kernel.org
Fixes: b90fa9ae8f51 ("[PATCH] shared mount handling: bind and rbind")
Tested-by: Andrei Vagin <avagin@virtuozzo.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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Michael Kerrisk <<mtk.manpages@gmail.com> writes:
I would like to write code that discovers the namespace setup on a live
system. The NS_GET_PARENT and NS_GET_USERNS ioctl() operations added in
Linux 4.9 provide much of what I want, but there are still a couple of
small pieces missing. Those pieces are added with this patch series.
Here's an example program that makes use of the new ioctl() operations.
8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---
/* ns_capable.c
(C) 2016 Michael Kerrisk, <mtk.manpages@gmail.com>
Licensed under the GNU General Public License v2 or later.
Test whether a process (identified by PID) might (subject to LSM checks)
have capabilities in a namespace (identified by a /proc/PID/ns/xxx file).
*/
} while (0)
exit(EXIT_FAILURE); } while (0)
/* Display capabilities sets of process with specified PID */
static void
show_cap(pid_t pid)
{
cap_t caps;
char *cap_string;
caps = cap_get_pid(pid);
if (caps == NULL)
errExit("cap_get_proc");
cap_string = cap_to_text(caps, NULL);
if (cap_string == NULL)
errExit("cap_to_text");
printf("Capabilities: %s\n", cap_string);
}
/* Obtain the effective UID pf the process 'pid' by
scanning its /proc/PID/file */
static uid_t
get_euid_of_process(pid_t pid)
{
char path[PATH_MAX];
char line[1024];
int uid;
snprintf(path, sizeof(path), "/proc/%ld/status", (long) pid);
FILE *fp;
fp = fopen(path, "r");
if (fp == NULL)
errExit("fopen-/proc/PID/status");
for (;;) {
if (fgets(line, sizeof(line), fp) == NULL) {
/* Should never happen... */
fprintf(stderr, "Failure scanning %s\n", path);
exit(EXIT_FAILURE);
}
if (strstr(line, "Uid:") == line) {
sscanf(line, "Uid: %*d %d %*d %*d", &uid);
return uid;
}
}
}
int
main(int argc, char *argv[])
{
int ns_fd, userns_fd, pid_userns_fd;
int nstype;
int next_fd;
struct stat pid_stat;
struct stat target_stat;
char *pid_str;
pid_t pid;
char path[PATH_MAX];
if (argc < 2) {
fprintf(stderr, "Usage: %s PID [ns-file]\n", argv[0]);
fprintf(stderr, "\t'ns-file' is a /proc/PID/ns/xxxx file; "
"if omitted, use the namespace\n"
"\treferred to by standard input "
"(file descriptor 0)\n");
exit(EXIT_FAILURE);
}
pid_str = argv[1];
pid = atoi(pid_str);
if (argc <= 2) {
ns_fd = STDIN_FILENO;
} else {
ns_fd = open(argv[2], O_RDONLY);
if (ns_fd == -1)
errExit("open-ns-file");
}
/* Get the relevant user namespace FD, which is 'ns_fd' if 'ns_fd' refers
to a user namespace, otherwise the user namespace that owns 'ns_fd' */
nstype = ioctl(ns_fd, NS_GET_NSTYPE);
if (nstype == -1)
errExit("ioctl-NS_GET_NSTYPE");
if (nstype == CLONE_NEWUSER) {
userns_fd = ns_fd;
} else {
userns_fd = ioctl(ns_fd, NS_GET_USERNS);
if (userns_fd == -1)
errExit("ioctl-NS_GET_USERNS");
}
/* Obtain 'stat' info for the user namespace of the specified PID */
snprintf(path, sizeof(path), "/proc/%s/ns/user", pid_str);
pid_userns_fd = open(path, O_RDONLY);
if (pid_userns_fd == -1)
errExit("open-PID");
if (fstat(pid_userns_fd, &pid_stat) == -1)
errExit("fstat-PID");
/* Get 'stat' info for the target user namesapce */
if (fstat(userns_fd, &target_stat) == -1)
errExit("fstat-PID");
/* If the PID is in the target user namespace, then it has
whatever capabilities are in its sets. */
if (pid_stat.st_dev == target_stat.st_dev &&
pid_stat.st_ino == target_stat.st_ino) {
printf("PID is in target namespace\n");
printf("Subject to LSM checks, it has the following capabilities\n");
show_cap(pid);
exit(EXIT_SUCCESS);
}
/* Otherwise, we need to walk through the ancestors of the target
user namespace to see if PID is in an ancestor namespace */
for (;;) {
int f;
next_fd = ioctl(userns_fd, NS_GET_PARENT);
if (next_fd == -1) {
/* The error here should be EPERM... */
if (errno != EPERM)
errExit("ioctl-NS_GET_PARENT");
printf("PID is not in an ancestor namespace\n");
printf("It has no capabilities in the target namespace\n");
exit(EXIT_SUCCESS);
}
if (fstat(next_fd, &target_stat) == -1)
errExit("fstat-PID");
/* If the 'stat' info for this user namespace matches the 'stat'
* info for 'next_fd', then the PID is in an ancestor namespace */
if (pid_stat.st_dev == target_stat.st_dev &&
pid_stat.st_ino == target_stat.st_ino)
break;
/* Next time round, get the next parent */
f = userns_fd;
userns_fd = next_fd;
close(f);
}
/* At this point, we found that PID is in an ancestor of the target
user namespace, and 'userns_fd' refers to the immediate descendant
user namespace of PID in the chain of user namespaces from PID to
the target user namespace. If the effective UID of PID matches the
owner UID of descendant user namespace, then PID has all
capabilities in the descendant namespace(s); otherwise, it just has
the capabilities that are in its sets. */
uid_t owner_uid, uid;
if (ioctl(userns_fd, NS_GET_OWNER_UID, &owner_uid) == -1) {
perror("ioctl-NS_GET_OWNER_UID");
exit(EXIT_FAILURE);
}
uid = get_euid_of_process(pid);
printf("PID is in an ancestor namespace\n");
if (owner_uid == uid) {
printf("And its effective UID matches the owner "
"of the namespace\n");
printf("Subject to LSM checks, PID has all capabilities in "
"that namespace!\n");
} else {
printf("But its effective UID does not match the owner "
"of the namespace\n");
printf("Subject to LSM checks, it has the following capabilities\n");
show_cap(pid);
}
exit(EXIT_SUCCESS);
}
8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---
Michael Kerrisk (2):
nsfs: Add an ioctl() to return the namespace type
nsfs: Add an ioctl() to return owner UID of a userns
fs/nsfs.c | 13 +++++++++++++
include/uapi/linux/nsfs.h | 9 +++++++--
2 files changed, 20 insertions(+), 2 deletions(-)
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I'd like to write code that discovers the user namespace hierarchy on a
running system, and also shows who owns the various user namespaces.
Currently, there is no way of getting the owner UID of a user namespace.
Therefore, this patch adds a new NS_GET_CREATOR_UID ioctl() that fetches
the UID (as seen in the user namespace of the caller) of the creator of
the user namespace referred to by the specified file descriptor.
If the supplied file descriptor does not refer to a user namespace,
the operation fails with the error EINVAL. If the owner UID does
not have a mapping in the caller's user namespace return the
overflow UID as that appears easier to deal with in practice
in user-space applications.
-- EWB Changed the handling of unmapped UIDs from -EOVERFLOW
back to the overflow uid. Per conversation with
Michael Kerrisk after examining his test code.
Acked-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Michael Kerrisk <mtk-manpages@gmail.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
|
|
Christoph Hellwig pointed out that there's a potentially nasty race when
performing simultaneous nearby directio cow writes:
"Thread 1 writes a range from B to c
" B --------- C
p
"a little later thread 2 writes from A to B
" A --------- B
p
[editor's note: the 'p' denote cowextsize boundaries, which I added to
make this more clear]
"but the code preallocates beyond B into the range where thread
"1 has just written, but ->end_io hasn't been called yet.
"But once ->end_io is called thread 2 has already allocated
"up to the extent size hint into the write range of thread 1,
"so the end_io handler will splice the unintialized blocks from
"that preallocation back into the file right after B."
We can avoid this race by ensuring that thread 1 cannot accidentally
remap the blocks that thread 2 allocated (as part of speculative
preallocation) as part of t2's write preparation in t1's end_io handler.
The way we make this happen is by taking advantage of the unwritten
extent flag as an intermediate step.
Recall that when we begin the process of writing data to shared blocks,
we create a delayed allocation extent in the CoW fork:
D: --RRRRRRSSSRRRRRRRR---
C: ------DDDDDDD---------
When a thread prepares to CoW some dirty data out to disk, it will now
convert the delalloc reservation into an /unwritten/ allocated extent in
the cow fork. The da conversion code tries to opportunistically
allocate as much of a (speculatively prealloc'd) extent as possible, so
we may end up allocating a larger extent than we're actually writing
out:
D: --RRRRRRSSSRRRRRRRR---
U: ------UUUUUUU---------
Next, we convert only the part of the extent that we're actively
planning to write to normal (i.e. not unwritten) status:
D: --RRRRRRSSSRRRRRRRR---
U: ------UURRUUU---------
If the write succeeds, the end_cow function will now scan the relevant
range of the CoW fork for real extents and remap only the real extents
into the data fork:
D: --RRRRRRRRSRRRRRRRR---
U: ------UU--UUU---------
This ensures that we never obliterate valid data fork extents with
unwritten blocks from the CoW fork.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
|
|
In the data fork, we only allow extents to perform the following state
transitions:
delay -> real <-> unwritten
There's no way to move directly from a delalloc reservation to an
/unwritten/ allocated extent. However, for the CoW fork we want to be
able to do the following to each extent:
delalloc -> unwritten -> written -> remapped to data fork
This will help us to avoid a race in the speculative CoW preallocation
code between a first thread that is allocating a CoW extent and a second
thread that is remapping part of a file after a write. In order to do
this, however, we need two things: first, we have to be able to
transition from da to unwritten, and second the function that converts
between real and unwritten has to be made aware of the cow fork. Do
both of those things.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
|
|
Perform basic sanity checking of the directory free block header
fields so that we avoid hanging the system on invalid data.
(Granted that just means that now we shutdown on directory write,
but that seems better than hanging...)
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
|
|
We can't handle a bmbt that's taller than BTREE_MAXLEVELS, and there's
no such thing as a zero-level bmbt (for that we have extents format),
so if we see this, send back an error code.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
|
|
Don't let anybody load an obviously bad btree pointer. Since the values
come from disk, we must return an error, not just ASSERT.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
|
|
When we open a directory, we try to readahead block 0 of the directory
on the assumption that we're going to need it soon. If the bmbt is
corrupt, the directory will never be usable and the readahead fails
immediately, so we might as well prevent the directory from being opened
at all. This prevents a subsequent read or modify operation from
hitting it and taking the fs offline.
NOTE: We're only checking for early failures in the block mapping, not
the readahead directory block itself.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
|
|
We use di_format and if_flags to decide whether we're grabbing the ilock
in btree mode (btree extents not loaded) or shared mode (anything else),
but the state of those fields can be changed by other threads that are
also trying to load the btree extents -- IFEXTENTS gets set before the
_bmap_read_extents call and cleared if it fails.
We don't actually need to have IFEXTENTS set until after the bmbt
records are successfully loaded and validated, which will fix the race
between multiple threads trying to read the same directory. The next
patch strengthens directory bmbt validation by refusing to open the
directory if reading the bmbt to start directory readahead fails.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
|
|
All merge conflicts were simple overlapping changes.
Signed-off-by: David S. Miller <davem@davemloft.net>
|
|
Pull nfsd fixes from Bruce Fields:
"Three more miscellaneous nfsd bugfixes"
* tag 'nfsd-4.10-2' of git://linux-nfs.org/~bfields/linux:
svcrpc: fix oops in absence of krb5 module
nfsd: special case truncates some more
NFSD: Fix a null reference case in find_or_create_lock_stateid()
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