Read and write operations are capped to MAX_RW_COUNT. Some read ops rely on
that limit, and that is not guaranteed by the IORING_OP_PROVIDE_BUFFERS.
Truncate those lengths when doing io_add_buffers, so buffer addresses still
use the uncapped length.
Also, take the chance and change struct io_buffer len member to __u32, so
it matches struct io_provide_buffer len member.
This fixes CVE-2021-3491, also reported as ZDI-CAN-13546.
Fixes: ddf0322db7 ("io_uring: add IORING_OP_PROVIDE_BUFFERS")
Reported-by: Billy Jheng Bing-Jhong (@st424204)
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently the -EINVAL error return path is leaking memory allocated
to data. Fix this by not returning immediately but instead setting
the error return variable to -EINVAL and breaking out of the loop.
Kudos to Pavel Begunkov for suggesting a correct fix.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/20210429104602.62676-1-colin.king@canonical.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Allow empty reg buffer slots any request using which should fail. This
allows users to not register all buffers in advance, but do it lazily
and/or on demand via updates. That is achieved by setting iov_base and
iov_len to zero for registration and/or buffer updates. Empty buffer
can't have a non-zero tag.
Implementation details: to not add extra overhead to io_import_fixed(),
create a dummy buffer crafted to fail any request using it, and set it
to all empty buffer slots.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/7e95e4d700082baaf010c648c72ac764c9cc8826.1619611868.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
CQE flags take one byte that we store in req->flags together with other
REQ_F_* internal flags. CQE flags are copied directly into req and then
verified that requires some handling on failures, e.g. to make sure that
that copy doesn't set some of the internal flags.
Move all internal flags to take bits after the first byte, so we don't
need extra handling and make it safer overall.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/b8b5b02d1ab9d786fcc7db4a3fe86db6b70b8987.1619536280.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Merge tag 'for-5.13/io_uring-2021-04-27' of git://git.kernel.dk/linux-block
Pull io_uring updates from Jens Axboe:
- Support for multi-shot mode for POLL requests
- More efficient reference counting. This is shamelessly stolen from
the mm side. Even though referencing is mostly single/dual user, the
128 count was retained to keep the code the same. Maybe this
should/could be made generic at some point.
- Removal of the need to have a manager thread for each ring. The
manager threads only job was checking and creating new io-threads as
needed, instead we handle this from the queue path.
- Allow SQPOLL without CAP_SYS_ADMIN or CAP_SYS_NICE. Since 5.12, this
thread is "just" a regular application thread, so no need to restrict
use of it anymore.
- Cleanup of how internal async poll data lifetime is managed.
- Fix for syzbot reported crash on SQPOLL cancelation.
- Make buffer registration more like file registrations, which includes
flexibility in avoiding full set unregistration and re-registration.
- Fix for io-wq affinity setting.
- Be a bit more defensive in task->pf_io_worker setup.
- Various SQPOLL fixes.
- Cleanup of SQPOLL creds handling.
- Improvements to in-flight request tracking.
- File registration cleanups.
- Tons of cleanups and little fixes
* tag 'for-5.13/io_uring-2021-04-27' of git://git.kernel.dk/linux-block: (156 commits)
io_uring: maintain drain logic for multishot poll requests
io_uring: Check current->io_uring in io_uring_cancel_sqpoll
io_uring: fix NULL reg-buffer
io_uring: simplify SQPOLL cancellations
io_uring: fix work_exit sqpoll cancellations
io_uring: Fix uninitialized variable up.resv
io_uring: fix invalid error check after malloc
io_uring: io_sq_thread() no longer needs to reset current->pf_io_worker
kernel: always initialize task->pf_io_worker to NULL
io_uring: update sq_thread_idle after ctx deleted
io_uring: add full-fledged dynamic buffers support
io_uring: implement fixed buffers registration similar to fixed files
io_uring: prepare fixed rw for dynanic buffers
io_uring: keep table of pointers to ubufs
io_uring: add generic rsrc update with tags
io_uring: add IORING_REGISTER_RSRC
io_uring: enumerate dynamic resources
io_uring: add generic path for rsrc update
io_uring: preparation for rsrc tagging
io_uring: decouple CQE filling from requests
...
Now that we have multishot poll requests, one SQE can emit multiple
CQEs. given below example:
sqe0(multishot poll)-->sqe1-->sqe2(drain req)
sqe2 is designed to issue after sqe0 and sqe1 completed, but since sqe0
is a multishot poll request, sqe2 may be issued after sqe0's event
triggered twice before sqe1 completed. This isn't what users leverage
drain requests for.
Here the solution is to wait for multishot poll requests fully
completed.
To achieve this, we should reconsider the req_need_defer equation, the
original one is:
all_sqes(excluding dropped ones) == all_cqes(including dropped ones)
This means we issue a drain request when all the previous submitted
SQEs have generated their CQEs.
Now we should consider multishot requests, we deduct all the multishot
CQEs except the cancellation one, In this way a multishot poll request
behave like a normal request, so:
all_sqes == all_cqes - multishot_cqes(except cancellations)
Here we introduce cq_extra for it.
Signed-off-by: Hao Xu <haoxu@linux.alibaba.com>
Link: https://lore.kernel.org/r/1618298439-136286-1-git-send-email-haoxu@linux.alibaba.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
syzkaller identified KASAN: null-ptr-deref Write in
io_uring_cancel_sqpoll.
io_uring_cancel_sqpoll is called by io_sq_thread before calling
io_uring_alloc_task_context. This leads to current->io_uring being NULL.
io_uring_cancel_sqpoll should not have to deal with threads where
current->io_uring is NULL.
In order to cast a wider safety net, perform input sanitisation directly
in io_uring_cancel_sqpoll and return for NULL value of current->io_uring.
This is safe since if current->io_uring isn't set, then there's no way
for the task to have submitted any requests.
Reported-by: syzbot+be51ca5a4d97f017cd50@syzkaller.appspotmail.com
Cc: stable@vger.kernel.org
Signed-off-by: Palash Oswal <hello@oswalpalash.com>
Link: https://lore.kernel.org/r/20210427125148.21816-1-hello@oswalpalash.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
io_import_fixed() doesn't expect a registered buffer slot to be NULL and
would fail stumbling on it. We don't allow it, but if during
__io_sqe_buffers_update() rsrc removal succeeds but following register
fails, we'll get such a situation.
Do it atomically and don't remove buffers until we sure that a new one
can be set.
Fixes: 634d00df5e ("io_uring: add full-fledged dynamic buffers support")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/830020f9c387acddd51962a3123b5566571b8c6d.1619446608.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
All sqpoll rings (even sharing sqpoll task) are currently dead bound
to the task that created them, iow when owner task dies it kills all
its SQPOLL rings and their inflight requests via task_work infra. It's
neither the nicist way nor the most convenient as adds extra
locking/waiting and dependencies.
Leave it alone and rely on SIGKILL being delivered on its thread group
exit, so there are only two cases left:
1) thread group is dying, so sqpoll task gets a signal and exit itself
cancelling all requests.
2) an sqpoll ring is dying. Because refs_kill() is called the sqpoll not
going to submit any new request, and that's what we need. And
io_ring_exit_work() will do all the cancellation itself before
actually killing ctx, so sqpoll doesn't need to worry about it.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/3cd7f166b9c326a2c932b70e71a655b03257b366.1619389911.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
After closing an SQPOLL ring, io_ring_exit_work() kicks in and starts
doing cancellations via io_uring_try_cancel_requests(). It will go
through io_uring_try_cancel_iowq(), which uses ctx->tctx_list, but as
SQPOLL task don't have a ctx note, its io-wq won't be reachable and so
is left not cancelled.
It will eventually cancelled when one of the tasks dies, but if a thread
group survives for long and changes rings, it will spawn lots of
unreclaimed resources and live locked works.
Cancel SQPOLL task's io-wq separately in io_ring_exit_work().
Cc: stable@vger.kernel.org
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/a71a7fe345135d684025bb529d5cb1d8d6b46e10.1619389911.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The variable up.resv is not initialized and is being checking for a
non-zero value in the call to _io_register_rsrc_update. Fix this by
explicitly setting the variable to 0.
Addresses-Coverity: ("Uninitialized scalar variable)"
Fixes: c3bdad0271 ("io_uring: add generic rsrc update with tags")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20210426094735.8320-1-colin.king@canonical.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
With dynamic buffer updates, registered buffers in the table may change
at any moment. First of all we want to prevent future races between
updating and importing (i.e. io_import_fixed()), where the latter one
may happen without uring_lock held, e.g. from io-wq.
Save the first loaded io_mapped_ubuf buffer and reuse.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/21a2302d07766ae956640b6f753292c45200fe8f.1619356238.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Instead of keeping a table of ubufs convert them into pointers to ubuf,
so we can atomically read one pointer and be sure that the content of
ubuf won't change.
Because it was already dynamically allocating imu->bvec, throw both
imu and bvec into a single structure so they can be allocated together.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/b96efa4c5febadeccf41d0e849ac099f4c83b0d3.1619356238.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a new io_uring_register() opcode for rsrc registeration. Instead of
accepting a pointer to resources, fds or iovecs, it @arg is now pointing
to a struct io_uring_rsrc_register, and the second argument tells how
large that struct is to make it easily extendible by adding new fields.
All that is done mainly to be able to pass in a pointer with tags. Pass
it in and enable CQE posting for file resources. Doesn't support setting
tags on update yet.
A design choice made here is to not post CQEs on rsrc de-registration,
but only when we updated-removed it by rsrc dynamic update.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/c498aaec32a4bb277b2406b9069662c02cdda98c.1619356238.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We need a way to notify userspace when a lazily removed resource
actually died out. This will be done by associating a tag, which is u64
exactly like req->user_data, with each rsrc (e.g. buffer of file). A CQE
will be posted once a resource is actually put down.
Tag 0 is a special value set by default, for whcih it don't generate an
CQE, so providing the old behaviour.
Don't expose it to the userspace yet, but prepare internally, allocate
buffers, add all posting hooks, etc.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/2e6beec5eabe7216bb61fb93cdf5aaf65812a9b0.1619356238.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
REQ_F_INFLIGHT deaccounting doesn't do any spinlocking or resource
freeing anymore, so it's safe to move it into the normal cleanup flow,
i.e. into io_clean_op(), so making it cleaner.
Also move io_req_needs_clean() to be first in io_dismantle_req() so it
doesn't reload req->flags.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/90653a3a5de4107e3a00536fa4c2ea5f2c38a4ac.1618916549.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
[ 736.982891] INFO: task iou-sqp-4294:4295 blocked for more than 122 seconds.
[ 736.982897] Call Trace:
[ 736.982901] schedule+0x68/0xe0
[ 736.982903] io_uring_cancel_sqpoll+0xdb/0x110
[ 736.982908] io_sqpoll_cancel_cb+0x24/0x30
[ 736.982911] io_run_task_work_head+0x28/0x50
[ 736.982913] io_sq_thread+0x4e3/0x720
We call io_uring_cancel_sqpoll() one by one for each ctx either in
sq_thread() itself or via task works, and it's intended to cancel all
requests of a specified context. However the function uses per-task
counters to track the number of inflight requests, so it counts more
requests than available via currect io_uring ctx and goes to sleep for
them to appear (e.g. from IRQ), that will never happen.
Cancel a bit more than before, i.e. all ctxs that share sqpoll
and continue to use shared counters. Don't forget that we should not
remove ctx from the list before running that task_work sqpoll-cancel,
otherwise the function wouldn't be able to find the context and will
hang.
Reported-by: Joakim Hassila <joj@mac.com>
Reported-by: Jens Axboe <axboe@kernel.dk>
Fixes: 37d1e2e364 ("io_uring: move SQPOLL thread io-wq forked worker")
Cc: stable@vger.kernel.org
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1bded7e6c6b32e0bae25fce36be2868e46b116a0.1618752958.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Colin reported before possible overflow and sign extension problems in
io_provide_buffers_prep(). As Linus pointed out previous attempt did nothing
useful, see d81269fecb ("io_uring: fix provide_buffers sign extension").
Do that with help of check_<op>_overflow helpers. And fix struct
io_provide_buf::len type, as it doesn't make much sense to keep it
signed.
Reported-by: Colin Ian King <colin.king@canonical.com>
Fixes: efe68c1ca8 ("io_uring: validate the full range of provided buffers for access")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/46538827e70fce5f6cdb50897cff4cacc490f380.1618488258.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Don't fail submission attempts if there are CQEs in the overflow
backlog, but give away the decision making to the userspace. It
might be very inconvenient to the userspace, especially if
submission and completion are done by different threads.
We can remove it because of recent changes, where requests
are now not locked by the backlog, backlog entries are allocated
separately, so they take less space and cgroup accounted.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A hand-edit while applying this patch on top of a new base resulted in
a reverted check for re-issue, resulting in spurious -EAGAIN errors.
Fixes: 8c130827f4 ("io_uring: don't alter iopoll reissue fail ret code")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We manage these separately right now, just tie it to the request lifetime
and make it be part of the usual REQ_F_NEED_CLEANUP logic.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We have this in two spots right now, which is a bit fragile. In
preparation for moving REQ_F_POLLED cleanup into the same spot, move
the check into a separate helper so we only have it once.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The re-add handling isn't correct for the multi wait case, so let's
just disable it for now explicitly until we can get that sorted out. This
just turns it into a one-shot request. Since we pass back whether or not
a poll request terminates in multishot mode on completion, this should
not break properly behaving applications that check for IORING_CQE_F_MORE
on completion.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
[ 245.463317] INFO: task iou-sqp-1374:1377 blocked for more than 122 seconds.
[ 245.463334] task:iou-sqp-1374 state:D flags:0x00004000
[ 245.463345] Call Trace:
[ 245.463352] __schedule+0x36b/0x950
[ 245.463376] schedule+0x68/0xe0
[ 245.463385] __io_uring_cancel+0xfb/0x1a0
[ 245.463407] do_exit+0xc0/0xb40
[ 245.463423] io_sq_thread+0x49b/0x710
[ 245.463445] ret_from_fork+0x22/0x30
It happens when sqpoll forgot to run park_task_work and goes to exit,
then exiting user may remove ctx from sqd_list, and so corresponding
io_sq_thread() -> io_uring_cancel_sqpoll() won't be executed. Hopefully
it just stucks in do_exit() in this case.
Fixes: dbe1bdbb39 ("io_uring: handle signals for IO threads like a normal thread")
Reported-by: Joakim Hassila <joj@mac.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Having poll update function as a part of IORING_OP_POLL_ADD is not
great, we have to do hack around struct layouts and add some overhead in
the way of more popular POLL_ADD. Even more serious drawback is that
POLL_ADD requires file and always grabs it, and so poll update, which
doesn't need it.
Incorporate poll update into IORING_OP_POLL_REMOVE instead of
IORING_OP_POLL_ADD. It also more consistent with timeout remove/update.
Fixes: b69de288e9 ("io_uring: allow events and user_data update of running poll requests")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Isolate poll mask SQE parsing and preparations into a new function,
which will be reused shortly.
Fixes: b69de288e9 ("io_uring: allow events and user_data update of running poll requests")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Don't allow REQ_OP_POLL_REMOVE to kill apoll requests, users should not
know about it. Also, remove weird -EACCESS in io_poll_update(), it
shouldn't know anything about apoll, and have to work even if happened
to have a poll and an async poll'ed request with same user_data.
Fixes: b69de288e9 ("io_uring: allow events and user_data update of running poll requests")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Don't reinit io_ring_exit_work()'s exit work/completions on each
iteration, that's wasteful. Also add list_rotate_left(), so if we failed
to complete the task job, we don't try it again and again but defer it
until others are processed.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The only way to get out of io_iopoll_getevents() and continue iterating
is to have empty iopoll_list, otherwise the main loop would just exit.
So, instead of the unlock on 8th time heuristic, do that based on
iopoll_list.
Also, as no one can add new requests to iopoll_list while
io_iopoll_check() hold uring_lock, it's useless to spin with the list
empty, return in that case.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/5b8ebe84f5fff7ffa1f708952dfef7fc78b668e2.1618278933.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Thadeu Lima de Souza Cascardo