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io_uring: call req_set_fail_links() on short send[msg]()/recv[msg]() with MSG_WAITALL 

Without that it's not safe to use them in a linked combination with
others.

Now combinations like IORING_OP_SENDMSG followed by IORING_OP_SPLICE
should be possible.

We already handle short reads and writes for the following opcodes:

- IORING_OP_READV
- IORING_OP_READ_FIXED
- IORING_OP_READ
- IORING_OP_WRITEV
- IORING_OP_WRITE_FIXED
- IORING_OP_WRITE
- IORING_OP_SPLICE
- IORING_OP_TEE

Now we have it for these as well:

- IORING_OP_SENDMSG
- IORING_OP_SEND
- IORING_OP_RECVMSG
- IORING_OP_RECV

For IORING_OP_RECVMSG we also check for the MSG_TRUNC and MSG_CTRUNC
flags in order to call req_set_fail_links().

There might be applications arround depending on the behavior
that even short send[msg]()/recv[msg]() retuns continue an
IOSQE_IO_LINK chain.

It's very unlikely that such applications pass in MSG_WAITALL,
which is only defined in 'man 2 recvmsg', but not in 'man 2 sendmsg'.

It's expected that the low level sock_sendmsg() call just ignores
MSG_WAITALL, as MSG_ZEROCOPY is also ignored without explicitly set
SO_ZEROCOPY.

We also expect the caller to know about the implicit truncation to
MAX_RW_COUNT, which we don't detect.

cc: netdev@vger.kernel.org
Link: https://lore.kernel.org/r/c4e1a4cc0d905314f4d5dc567e65a7b09621aab3.1615908477.git.metze@samba.org
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
rM2-mainline
Stefan Metzmacher 2021-03-20 20:33:36 +01:00 committed by Jens Axboe
parent 00ddff431a
commit 0031275d11
1 changed files with 20 additions and 4 deletions
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24
fs/io_uring.c
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@ -4386,6 +4386,7 @@ static int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags)
struct io_async_msghdr iomsg, *kmsg;
struct socket *sock;
unsigned flags;
int min_ret = 0;
int ret;
sock = sock_from_file(req->file);
@ -4406,6 +4407,9 @@ static int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags)
else if (issue_flags & IO_URING_F_NONBLOCK)
flags |= MSG_DONTWAIT;
if (flags & MSG_WAITALL)
min_ret = iov_iter_count(&kmsg->msg.msg_iter);
ret = __sys_sendmsg_sock(sock, &kmsg->msg, flags);
if ((issue_flags & IO_URING_F_NONBLOCK) && ret == -EAGAIN)
return io_setup_async_msg(req, kmsg);
@ -4416,7 +4420,7 @@ static int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags)
if (kmsg->free_iov)
kfree(kmsg->free_iov);
req->flags &= ~REQ_F_NEED_CLEANUP;
if (ret < 0)
if (ret < min_ret)
req_set_fail_links(req);
__io_req_complete(req, issue_flags, ret, 0);
return 0;
@ -4429,6 +4433,7 @@ static int io_send(struct io_kiocb *req, unsigned int issue_flags)
struct iovec iov;
struct socket *sock;
unsigned flags;
int min_ret = 0;
int ret;
sock = sock_from_file(req->file);
@ -4450,6 +4455,9 @@ static int io_send(struct io_kiocb *req, unsigned int issue_flags)
else if (issue_flags & IO_URING_F_NONBLOCK)
flags |= MSG_DONTWAIT;
if (flags & MSG_WAITALL)
min_ret = iov_iter_count(&msg.msg_iter);
msg.msg_flags = flags;
ret = sock_sendmsg(sock, &msg);
if ((issue_flags & IO_URING_F_NONBLOCK) && ret == -EAGAIN)
@ -4457,7 +4465,7 @@ static int io_send(struct io_kiocb *req, unsigned int issue_flags)
if (ret == -ERESTARTSYS)
ret = -EINTR;
if (ret < 0)
if (ret < min_ret)
req_set_fail_links(req);
__io_req_complete(req, issue_flags, ret, 0);
return 0;
@ -4609,6 +4617,7 @@ static int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
struct socket *sock;
struct io_buffer *kbuf;
unsigned flags;
int min_ret = 0;
int ret, cflags = 0;
bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
@ -4640,6 +4649,9 @@ static int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
else if (force_nonblock)
flags |= MSG_DONTWAIT;
if (flags & MSG_WAITALL)
min_ret = iov_iter_count(&kmsg->msg.msg_iter);
ret = __sys_recvmsg_sock(sock, &kmsg->msg, req->sr_msg.umsg,
kmsg->uaddr, flags);
if (force_nonblock && ret == -EAGAIN)
@ -4653,7 +4665,7 @@ static int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
if (kmsg->free_iov)
kfree(kmsg->free_iov);
req->flags &= ~REQ_F_NEED_CLEANUP;
if (ret < 0)
if (ret < min_ret || ((flags & MSG_WAITALL) && (kmsg->msg.msg_flags & (MSG_TRUNC | MSG_CTRUNC))))
req_set_fail_links(req);
__io_req_complete(req, issue_flags, ret, cflags);
return 0;
@ -4668,6 +4680,7 @@ static int io_recv(struct io_kiocb *req, unsigned int issue_flags)
struct socket *sock;
struct iovec iov;
unsigned flags;
int min_ret = 0;
int ret, cflags = 0;
bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
@ -4699,6 +4712,9 @@ static int io_recv(struct io_kiocb *req, unsigned int issue_flags)
else if (force_nonblock)
flags |= MSG_DONTWAIT;
if (flags & MSG_WAITALL)
min_ret = iov_iter_count(&msg.msg_iter);
ret = sock_recvmsg(sock, &msg, flags);
if (force_nonblock && ret == -EAGAIN)
return -EAGAIN;
@ -4707,7 +4723,7 @@ static int io_recv(struct io_kiocb *req, unsigned int issue_flags)
out_free:
if (req->flags & REQ_F_BUFFER_SELECTED)
cflags = io_put_recv_kbuf(req);
if (ret < 0)
if (ret < min_ret || ((flags & MSG_WAITALL) && (msg.msg_flags & (MSG_TRUNC | MSG_CTRUNC))))
req_set_fail_links(req);
__io_req_complete(req, issue_flags, ret, cflags);
return 0;