The virtfs_reset() function is called either when the virtio-9p device
gets reset, or when the client starts a new 9P session. In both cases,
if it finds fids from a previous session, the following is printed in
the monitor:

9pfs:virtfs_reset: One or more uncluncked fids found during reset

For example, if a linux guest with a mounted 9P share is reset from the
monitor with system_reset, the message will be printed. This is excessive
since these fids are now clunked and the state is clean.
Signed-off-by: NGreg Kurz <groug@kaod.org>
Reviewed-by: NEric Blake <eblake@redhat.com>

A buggy or malicious guest could pass the id of an already opened fid and
cause QEMU to abort. Let's return EINVAL to the guest instead.
Signed-off-by: NGreg Kurz <groug@kaod.org>
Reviewed-by: NEric Blake <eblake@redhat.com>

The xattrcreate operation only makes sense on a freshly cloned fid
actually, since any open state would be leaked because of the fid_type
change. This is indeed what the linux kernel client does:

	fid = clone_fid(fid);
	[...]
	retval = p9_client_xattrcreate(fid, name, value_len, flags);

This patch also reverts commit ff55e94d since we are sure that a fid
with type P9_FID_NONE doesn't have a previously allocated xattr.
Signed-off-by: NGreg Kurz <groug@kaod.org>

We shouldn't allow guests to create extended attribute with arbitrary sizes.
On linux hosts, the limit is XATTR_SIZE_MAX. Let's use it.
Signed-off-by: NGreg Kurz <groug@kaod.org>

The v9fs_xattr_read() and v9fs_xattr_write() are passed a guest
originated offset: they must ensure this offset does not go beyond
the size of the extended attribute that was set in v9fs_xattrcreate().
Unfortunately, the current code implement these checks with unsafe
calculations on 32 and 64 bit values, which may allow a malicious
guest to cause OOB access anyway.

Fix this by comparing the offset and the xattr size, which are
both uint64_t, before trying to compute the effective number of bytes
to read or write.
Suggested-by: NGreg Kurz <groug@kaod.org>
Signed-off-by: NLi Qiang <liqiang6-s@360.cn>
Reviewed-by: NGreg Kurz <groug@kaod.org>
Reviewed-By: NGuido Günther <agx@sigxcpu.org>
Signed-off-by: NGreg Kurz <groug@kaod.org>

Currently, 9pfs sets the 'copied_len' field in V9fsXattr
to -1 to tag xattr walk fid. As the 'copied_len' is also
used to account for copied bytes, this may make confusion. This patch
add a bool 'xattrwalk_fid' to tag the xattr walk fid.
Suggested-by: NGreg Kurz <groug@kaod.org>
Signed-off-by: NLi Qiang <liqiang6-s@360.cn>
Reviewed-by: NGreg Kurz <groug@kaod.org>
Signed-off-by: NGreg Kurz <groug@kaod.org>

If an error occurs when marshalling the transfer length to the guest, the
v9fs_write() function doesn't free an IO vector, thus leading to a memory
leak. This patch fixes the issue.
Signed-off-by: NLi Qiang <liqiang6-s@360.cn>
Reviewed-by: NGreg Kurz <groug@kaod.org>
[groug, rephrased the changelog]
Signed-off-by: NGreg Kurz <groug@kaod.org>

The v9fs_link() function keeps a reference on the source fid object. This
causes a memory leak since the reference never goes down to 0. This patch
fixes the issue.
Signed-off-by: NLi Qiang <liqiang6-s@360.cn>
Reviewed-by: NGreg Kurz <groug@kaod.org>
[groug, rephrased the changelog]
Signed-off-by: NGreg Kurz <groug@kaod.org>

The 'fs.xattr.value' field in V9fsFidState object doesn't consider the
situation that this field has been allocated previously. Every time, it
will be allocated directly. This leads to a host memory leak issue if
the client sends another Txattrcreate message with the same fid number
before the fid from the previous time got clunked.
Signed-off-by: NLi Qiang <liqiang6-s@360.cn>
Reviewed-by: NGreg Kurz <groug@kaod.org>
[groug, updated the changelog to indicate how the leak can occur]
Signed-off-by: NGreg Kurz <groug@kaod.org>

9pfs uses g_malloc() to allocate the xattr memory space, if the guest
reads this memory before writing to it, this will leak host heap memory
to the guest. This patch avoid this.
Signed-off-by: NLi Qiang <liqiang6-s@360.cn>
Reviewed-by: NGreg Kurz <groug@kaod.org>
Signed-off-by: NGreg Kurz <groug@kaod.org>

Virtio devices should implement the VirtIODevice->reset() function to
perform necessary cleanup actions and to bring the device to a quiescent
state.

In the case of the virtio-9p device, this means:
- emptying the list of active PDUs (i.e. draining all in-flight I/O)
- freeing all fids (i.e. close open file descriptors and free memory)

That's what this patch does.

The reset handler first waits for all active PDUs to complete. Since
completion happens in the QEMU global aio context, we just have to
loop around aio_poll() until the active list is empty.

The freeing part involves some actions to be performed on the backend,
like closing file descriptors or flushing extended attributes to the
underlying filesystem. The virtfs_reset() function already does the
job: it calls free_fid() for all open fids not involved in an ongoing
I/O operation. We are sure this is the case since we have drained
the PDU active list.

The current code implements all backend accesses with coroutines, but we
want to stay synchronous on the reset path. We can either change the
current code to be able to run when not in coroutine context, or create
a coroutine context and wait for virtfs_reset() to complete. This patch
goes for the latter because it results in simpler code.

Note that we also need to create a dummy PDU because it is also an API
to pass the FsContext pointer to all backend callbacks.
Signed-off-by: NGreg Kurz <groug@kaod.org>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>

If a PDU has a flush request pending, the current code calls pdu_free()
twice:

1) pdu_complete()->pdu_free() with pdu->cancelled set, which does nothing

2) v9fs_flush()->pdu_free() with pdu->cancelled cleared, which moves the
   PDU back to the free list.

This works but it complexifies the logic of pdu_free().

With this patch, pdu_complete() only calls pdu_free() if no flush request
is pending, i.e. qemu_co_queue_next() returns false.

Since pdu_free() is now supposed to be called with pdu->cancelled cleared,
the check in pdu_free() is dropped and replaced by an assertion.
Signed-off-by: NGreg Kurz <groug@kaod.org>

Out of the three users of pdu_free(), none ever passes a NULL pointer to
this function.
Signed-off-by: NGreg Kurz <groug@kaod.org>

All these functions either call the v9fs_co_* functions which have the
coroutine_fn annotation, or pdu_complete() which calls qemu_co_queue_next().

Let's mark them to make it obvious they execute in coroutine context.
Signed-off-by: NGreg Kurz <groug@kaod.org>

In 9pfs read dispatch function, it doesn't free two QEMUIOVector
object thus causing potential memory leak. This patch avoid this.
Signed-off-by: NLi Qiang <liqiang6-s@360.cn>
Signed-off-by: NGreg Kurz <groug@kaod.org>

If a guest sends an empty string paramater to any 9P operation, the current
code unmarshals it into a V9fsString equal to { .size = 0, .data = NULL }.

This is unfortunate because it can cause NULL pointer dereference to happen
at various locations in the 9pfs code. And we don't want to check str->data
everywhere we pass it to strcmp() or any other function which expects a
dereferenceable pointer.

This patch enforces the allocation of genuine C empty strings instead, so
callers don't have to bother.

Out of all v9fs_iov_vunmarshal() users, only v9fs_xattrwalk() checks if
the returned string is empty. It now uses v9fs_string_size() since
name.data cannot be NULL anymore.
Signed-off-by: NLi Qiang <liqiang6-s@360.cn>
[groug, rewritten title and changelog,
 fix empty string check in v9fs_xattrwalk()]
Signed-off-by: NGreg Kurz <groug@kaod.org>

If the call to fid_to_qid() returns an error, we will call v9fs_path_free()
on uninitialized paths.

It is a regression introduced by the following commit:

56f101ec 9pfs: handle walk of ".." in the root directory

Let's fix this by initializing dpath and path before calling fid_to_qid().
Signed-off-by: NGreg Kurz <groug@kaod.org>
Reviewed-by: NCédric Le Goater <clg@kaod.org>
[groug: updated the changelog to indicate this is regression and to provide
        the offending commit SHA1]
Signed-off-by: NGreg Kurz <groug@kaod.org>

This helper is similar to v9fs_string_sprintf(), but it includes the
terminating NUL character in the size field.

This is to avoid doing v9fs_string_sprintf((V9fsString *) &path) and
then bumping the size.

Affected users are changed to use this new helper.
Signed-off-by: NGreg Kurz <groug@kaod.org>
Reviewed-by: NCédric Le Goater <clg@kaod.org>

The v9fs_string_null() function just calls v9fs_string_free(). Also it
only has 4 users, whereas v9fs_string_free() has 87.

This patch converts users to call directly v9fs_string_free() and drops
the useless function.
Signed-off-by: NGreg Kurz <groug@kaod.org>
Reviewed-by: NCédric Le Goater <clg@kaod.org>

The 9P spec at http://man.cat-v.org/plan_9/5/intro says:

All directories must support walks to the directory .. (dot-dot) meaning
parent directory, although by convention directories contain no explicit
entry for .. or . (dot).  The parent of the root directory of a server's
tree is itself.

This means that a client cannot walk further than the root directory
exported by the server. In other words, if the client wants to walk
"/.." or "/foo/../..", the server should answer like the request was
to walk "/".

This patch just does that:
- we cache the QID of the root directory at attach time
- during the walk we compare the QID of each path component with the root
  QID to detect if we're in a "/.." situation
- if so, we skip the current component and go to the next one
Signed-off-by: NGreg Kurz <groug@kaod.org>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

According to the 9P spec http://man.cat-v.org/plan_9/5/open about the
create request:

The names . and .. are special; it is illegal to create files with these
names.

This patch causes the create and lcreate requests to fail with EINVAL if
the file name is either "." or "..".

Even if it isn't explicitly written in the spec, this patch extends the
checking to all requests that may cause a directory entry to be created:

    - mknod
    - rename
    - renameat
    - mkdir
    - link
    - symlink

The unlinkat request also gets patched for consistency (even if
rmdir("foo/..") is expected to fail according to POSIX.1-2001).

The various error values come from the linux manual pages.
Suggested-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NGreg Kurz <groug@kaod.org>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

Empty path components don't make sense for most commands and may cause
undefined behavior, depending on the backend.

Also, the walk request described in the 9P spec [1] clearly shows that
the client is supposed to send individual path components: the official
linux client never sends portions of path containing the / character for
example.

Moreover, the 9P spec [2] also states that a system can decide to restrict
the set of supported characters used in path components, with an explicit
mention "to remove slashes from name components".

This patch introduces a new name_is_illegal() helper that checks the
names sent by the client are not empty and don't contain unwanted chars.
Since 9pfs is only supported on linux hosts, only the / character is
checked at the moment. When support for other hosts (AKA. win32) is added,
other chars may need to be blacklisted as well.

If a client sends an illegal path component, the request will fail and
ENOENT is returned to the client.

[1] http://man.cat-v.org/plan_9/5/walk
[2] http://man.cat-v.org/plan_9/5/introSuggested-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NGreg Kurz <groug@kaod.org>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

In practice the entry argument is always known at creation time, and
it is confusing that sometimes qemu_coroutine_enter is used with a
non-NULL argument to re-enter a coroutine (this happens in
block/sheepdog.c and tests/test-coroutine.c).  So pass the opaque value
at creation time, for consistency with e.g. aio_bh_new.

Mostly done with the following semantic patch:

@ entry1 @
expression entry, arg, co;
@@
- co = qemu_coroutine_create(entry);
+ co = qemu_coroutine_create(entry, arg);
  ...
- qemu_coroutine_enter(co, arg);
+ qemu_coroutine_enter(co);

@ entry2 @
expression entry, arg;
identifier co;
@@
- Coroutine *co = qemu_coroutine_create(entry);
+ Coroutine *co = qemu_coroutine_create(entry, arg);
  ...
- qemu_coroutine_enter(co, arg);
+ qemu_coroutine_enter(co);

@ entry3 @
expression entry, arg;
@@
- qemu_coroutine_enter(qemu_coroutine_create(entry), arg);
+ qemu_coroutine_enter(qemu_coroutine_create(entry, arg));

@ reentry @
expression co;
@@
- qemu_coroutine_enter(co, NULL);
+ qemu_coroutine_enter(co);

except for the aforementioned few places where the semantic patch
stumbled (as expected) and for test_co_queue, which would otherwise
produce an uninitialized variable warning.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

This patch changes the 9p code to use readdir() again instead of
readdir_r(), which is deprecated in glibc 2.24.

All the locking was put in place by a previous patch.
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NGreg Kurz <gkurz@linux.vnet.ibm.com>

If several threads concurrently call readdir() with the same directory
stream pointer, it is possible that they all get a pointer to the same
dirent structure, whose content is overwritten each time readdir() is
called.

We must thus serialize accesses to the dirent structure.

This may be achieved with a mutex like below:

lock_mutex();

readdir();

// work with the dirent

unlock_mutex();

This patch adds all the locking, to prepare the switch to readdir().
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NGreg Kurz <gkurz@linux.vnet.ibm.com>

If we are to switch back to readdir(), we need a more complex type than
DIR * to be able to serialize concurrent accesses to the directory stream.

This patch introduces a placeholder type and fixes all users.
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NGreg Kurz <gkurz@linux.vnet.ibm.com>

Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NGreg Kurz <gkurz@linux.vnet.ibm.com>

Signed-off-by: NGreg Kurz <gkurz@linux.vnet.ibm.com>

Commit 57cb38b3 included qapi/error.h into qemu/osdep.h to get the
Error typedef.  Since then, we've moved to include qemu/osdep.h
everywhere.  Its file comment explains: "To avoid getting into
possible circular include dependencies, this file should not include
any other QEMU headers, with the exceptions of config-host.h,
compiler.h, os-posix.h and os-win32.h, all of which are doing a
similar job to this file and are under similar constraints."
qapi/error.h doesn't do a similar job, and it doesn't adhere to
similar constraints: it includes qapi-types.h.  That's in excess of
100KiB of crap most .c files don't actually need.

Add the typedef to qemu/typedefs.h, and include that instead of
qapi/error.h.  Include qapi/error.h in .c files that need it and don't
get it now.  Include qapi-types.h in qom/object.h for uint16List.

Update scripts/clean-includes accordingly.  Update it further to match
reality: replace config.h by config-target.h, add sysemu/os-posix.h,
sysemu/os-win32.h.  Update the list of includes in the qemu/osdep.h
comment quoted above similarly.

This reduces the number of objects depending on qapi/error.h from "all
of them" to less than a third.  Unfortunately, the number depending on
qapi-types.h shrinks only a little.  More work is needed for that one.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
[Fix compilation without the spice devel packages. - Paolo]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

The return code of virtqueue_pop/vring_pop is unused except to check for
errors or 0.  We can thus easily move allocation inside the functions
and just return a pointer to the VirtQueueElement.

The advantage is that we will be able to allocate only the space that
is needed for the actual size of the s/g list instead of the full
VIRTQUEUE_MAX_SIZE items.  Currently VirtQueueElement takes about 48K
of memory, and this kind of allocation puts a lot of stress on malloc.
By cutting the size by two or three orders of magnitude, malloc can
use much more efficient algorithms.

The patch is pretty large, but changes to each device are testable
more or less independently.  Splitting it would mostly add churn.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: NCornelia Huck <cornelia.huck@de.ibm.com>

Clean up includes so that osdep.h is included first and headers
which it implies are not included manually.

This commit was created with scripts/clean-includes.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Message-id: 1453832250-766-18-git-send-email-peter.maydell@linaro.org

Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NGreg Kurz <gkurz@linux.vnet.ibm.com>

V9fsState now only contains generic fields. Introduce V9fsVirtioState
for virtio transport.  Change virtio-pci and virtio-ccw to use
V9fsVirtioState.
Signed-off-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

Signed-off-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

Now that file only contains generic code.
Signed-off-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

It's not virtio specific.
Signed-off-by: NWei Liu <wei.liu2@citrix.com>

It's only used in virtio device.
Signed-off-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

They will be used in later patches.
Signed-off-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

The new function resides in virtio specific file.
Signed-off-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

Signed-off-by: NWei Liu <wei.liu2@citrix.com>
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>