commit 29be9100aca2915fab54b5693309bc42956542e5 upstream.
Don't cross a mountpoint that explicitly specifies a backup volume
(target is <vol>.backup) when starting from a backup volume.
It it not uncommon to mount a volume's backup directly in the volume
itself. This can cause tools that are not paying attention to get
into a loop mounting the volume onto itself as they attempt to
traverse the tree, leading to a variety of problems.
This doesn't prevent the general case of loops in a sequence of
mountpoints, but addresses a common special case in the same way
as other afs clients.
Reported-by: Jan Henrik Sylvester <jan.henrik.sylvester@uni-hamburg.de>
Link: http://lists.infradead.org/pipermail/linux-afs/2024-May/008454.html
Reported-by: Markus Suvanto <markus.suvanto@gmail.com>
Link: http://lists.infradead.org/pipermail/linux-afs/2024-February/008074.html
Signed-off-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/768760.1716567475@warthog.procyon.org.uk
Reviewed-by: Jeffrey Altman <jaltman@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 0aec3847d044273733285dcff90afda89ad461d2 ]
This reverts commit 57e9d49c54528c49b8bffe6d99d782ea051ea534.
This undoes the hiding of .__afsXXXX silly-rename files. The problem with
hiding them is that rm can't then manually delete them.
This also reverts commit 5f7a07646655fb4108da527565dcdc80124b14c4 ("afs: Fix
endless loop in directory parsing") as that's a bugfix for the above.
Fixes: 57e9d49c5452 ("afs: Hide silly-rename files from userspace")
Reported-by: Markus Suvanto <markus.suvanto@gmail.com>
Link: https://lists.infradead.org/pipermail/linux-afs/2024-February/008102.html
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/3085695.1710328121@warthog.procyon.org.uk
Reviewed-by: Jeffrey E Altman <jaltman@auristor.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 5f7a07646655fb4108da527565dcdc80124b14c4 ]
If a directory has a block with only ".__afsXXXX" files in it (from
uncompleted silly-rename), these .__afsXXXX files are skipped but without
advancing the file position in the dir_context. This leads to
afs_dir_iterate() repeating the block again and again.
Fix this by making the code that skips the .__afsXXXX file also manually
advance the file position.
The symptoms are a soft lookup:
watchdog: BUG: soft lockup - CPU#3 stuck for 52s! [check:5737]
...
RIP: 0010:afs_dir_iterate_block+0x39/0x1fd
...
? watchdog_timer_fn+0x1a6/0x213
...
? asm_sysvec_apic_timer_interrupt+0x16/0x20
? afs_dir_iterate_block+0x39/0x1fd
afs_dir_iterate+0x10a/0x148
afs_readdir+0x30/0x4a
iterate_dir+0x93/0xd3
__do_sys_getdents64+0x6b/0xd4
This is almost certainly the actual fix for:
https://bugzilla.kernel.org/show_bug.cgi?id=218496
Fixes: 57e9d49c5452 ("afs: Hide silly-rename files from userspace")
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/786185.1708694102@warthog.procyon.org.uk
Reviewed-by: Marc Dionne <marc.dionne@auristor.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Markus Suvanto <markus.suvanto@gmail.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 6ea38e2aeb72349cad50e38899b0ba6fbcb2af3d ]
The max length of volume->vid value is 20 characters.
So increase idbuf[] size up to 24 to avoid overflow.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
[DH: Actually, it's 20 + NUL, so increase it to 24 and use snprintf()]
Fixes: d2ddc776a458 ("afs: Overhaul volume and server record caching and fileserver rotation")
Signed-off-by: Daniil Dulov <d.dulov@aladdin.ru>
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20240211150442.3416-1-d.dulov@aladdin.ru/ # v1
Link: https://lore.kernel.org/r/20240212083347.10742-1-d.dulov@aladdin.ru/ # v2
Link: https://lore.kernel.org/r/20240219143906.138346-3-dhowells@redhat.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 1702e0654ca9a7bcd7c7619c8a5004db58945b71 ]
David Howells says:
(5) afs_find_server().
There could be a lot of servers in the list and each server can have
multiple addresses, so I think this would be better with an exclusive
second pass.
The server list isn't likely to change all that often, but when it does
change, there's a good chance several servers are going to be
added/removed one after the other. Further, this is only going to be
used for incoming cache management/callback requests from the server,
which hopefully aren't going to happen too often - but it is remotely
drivable.
(6) afs_find_server_by_uuid().
Similarly to (5), there could be a lot of servers to search through, but
they are in a tree not a flat list, so it should be faster to process.
Again, it's not likely to change that often and, again, when it does
change it's likely to involve multiple changes. This can be driven
remotely by an incoming cache management request but is mostly going to
be driven by setting up or reconfiguring a volume's server list -
something that also isn't likely to happen often.
Make the "seq" counter odd on the 2nd pass, otherwise read_seqbegin_or_lock()
never takes the lock.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/r/20231130115614.GA21581@redhat.com/
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 4121b4337146b64560d1e46ebec77196d9287802 ]
David Howells says:
(2) afs_lookup_volume_rcu().
There can be a lot of volumes known by a system. A thousand would
require a 10-step walk and this is drivable by remote operation, so I
think this should probably take a lock on the second pass too.
Make the "seq" counter odd on the 2nd pass, otherwise read_seqbegin_or_lock()
never takes the lock.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/r/20231130115606.GA21571@redhat.com/
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 57e9d49c54528c49b8bffe6d99d782ea051ea534 ]
There appears to be a race between silly-rename files being created/removed
and various userspace tools iterating over the contents of a directory,
leading to such errors as:
find: './kernel/.tmp_cpio_dir/include/dt-bindings/reset/.__afs2080': No such file or directory
tar: ./include/linux/greybus/.__afs3C95: File removed before we read it
when building a kernel.
Fix afs_readdir() so that it doesn't return .__afsXXXX silly-rename files
to userspace. This doesn't stop them being looked up directly by name as
we need to be able to look them up from within the kernel as part of the
silly-rename algorithm.
Fixes: 79ddbfa500b3 ("afs: Implement sillyrename for unlink and rename")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit a9e01ac8c5ff32669119c40dfdc9e80eb0b7d7aa ]
In afs_update_cell(), ret is the result of the DNS lookup and the errors
are to be handled by a switch - however, the value gets clobbered in
between by setting it to -ENOMEM in case afs_alloc_vlserver_list()
fails.
Fix this by moving the setting of -ENOMEM into the error handling for
OOM failure. Further, only do it if we don't have an alternative error
to return.
Found by Linux Verification Center (linuxtesting.org) with SVACE. Based
on a patch from Anastasia Belova [1].
Fixes: d5c32c89b208 ("afs: Fix cell DNS lookup")
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeffrey Altman <jaltman@auristor.com>
cc: Anastasia Belova <abelova@astralinux.ru>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
cc: lvc-project@linuxtesting.org
Link: https://lore.kernel.org/r/20231221085849.1463-1-abelova@astralinux.ru/ [1]
Link: https://lore.kernel.org/r/1700862.1703168632@warthog.procyon.org.uk/ # v1
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 74cef6872ceaefb5b6c5c60641371ea28702d358 ]
In the afs dynamic root directory, the ->lookup() function does a DNS check
on the cell being asked for and if the DNS upcall reports an error it will
report an error back to userspace (typically ENOENT).
However, if a failed DNS upcall returns a new-style result, it will return
a valid result, with the status field set appropriately to indicate the
type of failure - and in that case, dns_query() doesn't return an error and
we let stat() complete with no error - which can cause confusion in
userspace as subsequent calls that trigger d_automount then fail with
ENOENT.
Fix this by checking the status result from a valid dns_query() and
returning an error if it indicates a failure.
Fixes: bbb4c4323a4d ("dns: Allow the dns resolver to retrieve a server set")
Reported-by: Markus Suvanto <markus.suvanto@gmail.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=216637
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Markus Suvanto <markus.suvanto@gmail.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 71f8b55bc30e82d6355e07811213d847981a32e2 ]
Fix the afs dynamic root's d_delete function to always delete unused
dentries rather than only deleting them if they're positive. With things
as they stand upstream, negative dentries stemming from failed DNS lookups
stick around preventing retries.
Fixes: 66c7e1d319a5 ("afs: Split the dynroot stuff out and give it its own ops tables")
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Markus Suvanto <markus.suvanto@gmail.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 52bf9f6c09fca8c74388cd41cc24e5d1bff812a9 ]
If an AFS cell that has an unreachable (eg. ENETUNREACH) server listed (VL
server or fileserver), an asynchronous probe to one of its addresses may
fail immediately because sendmsg() returns an error. When this happens, a
refcount underflow can happen if certain events hit a very small window.
The way this occurs is:
(1) There are two levels of "call" object, the afs_call and the
rxrpc_call. Each of them can be transitioned to a "completed" state
in the event of success or failure.
(2) Asynchronous afs_calls are self-referential whilst they are active to
prevent them from evaporating when they're not being processed. This
reference is disposed of when the afs_call is completed.
Note that an afs_call may only be completed once; once completed
completing it again will do nothing.
(3) When a call transmission is made, the app-side rxrpc code queues a Tx
buffer for the rxrpc I/O thread to transmit. The I/O thread invokes
sendmsg() to transmit it - and in the case of failure, it transitions
the rxrpc_call to the completed state.
(4) When an rxrpc_call is completed, the app layer is notified. In this
case, the app is kafs and it schedules a work item to process events
pertaining to an afs_call.
(5) When the afs_call event processor is run, it goes down through the
RPC-specific handler to afs_extract_data() to retrieve data from rxrpc
- and, in this case, it picks up the error from the rxrpc_call and
returns it.
The error is then propagated to the afs_call and that is completed
too. At this point the self-reference is released.
(6) If the rxrpc I/O thread manages to complete the rxrpc_call within the
window between rxrpc_send_data() queuing the request packet and
checking for call completion on the way out, then
rxrpc_kernel_send_data() will return the error from sendmsg() to the
app.
(7) Then afs_make_call() will see an error and will jump to the error
handling path which will attempt to clean up the afs_call.
(8) The problem comes when the error handling path in afs_make_call()
tries to unconditionally drop an async afs_call's self-reference.
This self-reference, however, may already have been dropped by
afs_extract_data() completing the afs_call
(9) The refcount underflows when we return to afs_do_probe_vlserver() and
that tries to drop its reference on the afs_call.
Fix this by making afs_make_call() attempt to complete the afs_call rather
than unconditionally putting it. That way, if afs_extract_data() manages
to complete the call first, afs_make_call() won't do anything.
The bug can be forced by making do_udp_sendmsg() return -ENETUNREACH and
sticking an msleep() in rxrpc_send_data() after the 'success:' label to
widen the race window.
The error message looks something like:
refcount_t: underflow; use-after-free.
WARNING: CPU: 3 PID: 720 at lib/refcount.c:28 refcount_warn_saturate+0xba/0x110
...
RIP: 0010:refcount_warn_saturate+0xba/0x110
...
afs_put_call+0x1dc/0x1f0 [kafs]
afs_fs_get_capabilities+0x8b/0xe0 [kafs]
afs_fs_probe_fileserver+0x188/0x1e0 [kafs]
afs_lookup_server+0x3bf/0x3f0 [kafs]
afs_alloc_server_list+0x130/0x2e0 [kafs]
afs_create_volume+0x162/0x400 [kafs]
afs_get_tree+0x266/0x410 [kafs]
vfs_get_tree+0x25/0xc0
fc_mount+0xe/0x40
afs_d_automount+0x1b3/0x390 [kafs]
__traverse_mounts+0x8f/0x210
step_into+0x340/0x760
path_openat+0x13a/0x1260
do_filp_open+0xaf/0x160
do_sys_openat2+0xaf/0x170
or something like:
refcount_t: underflow; use-after-free.
...
RIP: 0010:refcount_warn_saturate+0x99/0xda
...
afs_put_call+0x4a/0x175
afs_send_vl_probes+0x108/0x172
afs_select_vlserver+0xd6/0x311
afs_do_cell_detect_alias+0x5e/0x1e9
afs_cell_detect_alias+0x44/0x92
afs_validate_fc+0x9d/0x134
afs_get_tree+0x20/0x2e6
vfs_get_tree+0x1d/0xc9
fc_mount+0xe/0x33
afs_d_automount+0x48/0x9d
__traverse_mounts+0xe0/0x166
step_into+0x140/0x274
open_last_lookups+0x1c1/0x1df
path_openat+0x138/0x1c3
do_filp_open+0x55/0xb4
do_sys_openat2+0x6c/0xb6
Fixes: 34fa47612bfe ("afs: Fix race in async call refcounting")
Reported-by: Bill MacAllister <bill@ca-zephyr.org>
Closes: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1052304
Suggested-by: Jeffrey E Altman <jaltman@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeffrey Altman <jaltman@auristor.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/r/2633992.1702073229@warthog.procyon.org.uk/ # v1
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit b590eb41be766c5a63acc7e8896a042f7a4e8293 ]
AFS doesn't really do locking on R/O volumes as fileservers don't maintain
state with each other and thus a lock on a R/O volume file on one
fileserver will not be be visible to someone looking at the same file on
another fileserver.
Further, the server may return an error if you try it.
Fix this by doing what other AFS clients do and handle filelocking on R/O
volume files entirely within the client and don't touch the server.
Fixes: 6c6c1d63c243 ("afs: Provide mount-time configurable byte-range file locking emulation")
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 0167236e7d66c5e1e85d902a6abc2529b7544539 ]
Make AFS return error ENOENT if no cell SRV or AFSDB DNS record (or
cellservdb config file record) can be found rather than returning
EDESTADDRREQ.
Also add cell name lookup info to the cursor dump.
Fixes: d5c32c89b208 ("afs: Fix cell DNS lookup")
Reported-by: Markus Suvanto <markus.suvanto@gmail.com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216637
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 2a4ca1b4b77850544408595e2433f5d7811a9daa ]
When kafs tries to look up a cell in the DNS or the local config, it will
translate a lookup failure into EDESTADDRREQ whereas OpenAFS translates it
into ENOENT. Applications such as West expect the latter behaviour and
fail if they see the former.
This can be seen by trying to mount an unknown cell:
# mount -t afs %example.com:cell.root /mnt
mount: /mnt: mount(2) system call failed: Destination address required.
Fixes: 4d673da14533 ("afs: Support the AFS dynamic root")
Reported-by: Markus Suvanto <markus.suvanto@gmail.com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216637
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeffrey Altman <jaltman@auristor.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit e6bace7313d61e31f2b16fa3d774fd8cb3cb869e ]
afs_server_list is accessed with the rcu_read_lock() held from
volume->servers, so it needs to be cleaned up correctly.
Fix this by using kfree_rcu() instead of kfree().
Fixes: 8a070a964877 ("afs: Detect cell aliases 1 - Cells with root volumes")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
