[net,v4,4/4] test/vsock: copy to user failure test

Commit Message

Arseniy Krasnov March 14, 2023, 10:47 a.m. UTC

This adds SOCK_STREAM and SOCK_SEQPACKET tests for invalid buffer case.
It tries to read data to NULL buffer (data already presents in socket's
queue), then uses valid buffer. For SOCK_STREAM second read must return
data, because skbuff is not dropped, but for SOCK_SEQPACKET skbuff will
be dropped by kernel, and 'recv()' will return EAGAIN.

Signed-off-by: Arseniy Krasnov <[e-mail]>
Reviewed-by: Stefano Garzarella <[e-mail]>
---
 tools/testing/vsock/vsock_test.c | 118 +++++++++++++++++++++++++++++++
 1 file changed, 118 insertions(+)

Comments

Arseniy Krasnov March 14, 2023, 10:55 a.m. UTC | #1

Hmmm, that's really strange, i don't see CV in mailing lists. Here it is anyway:

Subject: [PATCH net v4 0/4] several updates to virtio/vsock

Hello,

this patchset evolved from previous v2 version (see link below). It does
several updates to virtio/vsock:
1) Changes 'virtio_transport_inc/dec_rx_pkt()' interface. Now instead of
   using skbuff state ('head' and 'data' pointers) to update 'fwd_cnt'
   and 'rx_bytes', integer value is passed as an input argument. This
   makes code more simple, because in this case we don't need to update
   skbuff state before calling 'virtio_transport_inc/dec_rx_pkt()'. In
   more common words - we don't need to change skbuff state to update
   'rx_bytes' and 'fwd_cnt' correctly.
2) For SOCK_STREAM, when copying data to user fails, current skbuff is
   not dropped. Next read attempt will use same skbuff and last offset.
   Instead of 'skb_dequeue()', 'skb_peek()' + '__skb_unlink()' are used.
   This behaviour was implemented before skbuff support.
3) For SOCK_SEQPACKET it removes unneeded 'skb_pull()' call, because for
   this type of socket each skbuff is used only once: after removing it
   from socket's queue, it will be freed anyway.

Test for 2) also added:
Test tries to 'recv()' data to NULL buffer, then does 'recv()' with valid
buffer. For SOCK_STREAM second 'recv()' must return data, because skbuff
must not be dropped, but for SOCK_SEQPACKET skbuff will be dropped by
kernel, and 'recv()' will return EAGAIN.

Link to v1 on lore:
https://lore.kernel.org/netdev/[e-mail]/

Link to v2 on lore:
https://lore.kernel.org/netdev/[e-mail]/

Link to v3 on lore:
https://lore.kernel.org/netdev/[e-mail]/

Change log:

v1 -> v2:
 - For SOCK_SEQPACKET call 'skb_pull()' also in case of copy failure or
   dropping skbuff (when we just waiting message end).
 - Handle copy failure for SOCK_STREAM in the same manner (plus free
   current skbuff).
 - Replace bug repdroducer with new test in vsock_test.c

v2 -> v3:
 - Replace patch which removes 'skb->len' subtraction from function
   'virtio_transport_dec_rx_pkt()' with patch which updates functions
   'virtio_transport_inc/dec_rx_pkt()' by passing integer argument
   instead of skbuff pointer.
 - Replace patch which drops skbuff when copying to user fails with
   patch which changes this behaviour by keeping skbuff in queue until
   it has no data.
 - Add patch for SOCK_SEQPACKET which removes redundant 'skb_pull()'
   call on read.
 - I remove "Fixes" tag from all patches, because all of them now change
   code logic, not only fix something.

v3 -> v4:
 - Update commit messages in all patches except test.
 - Add "Fixes" tag to all patches except test.

Arseniy Krasnov (4):
  virtio/vsock: don't use skbuff state to account credit
  virtio/vsock: remove redundant 'skb_pull()' call
  virtio/vsock: don't drop skbuff on copy failure
  test/vsock: copy to user failure test

 net/vmw_vsock/virtio_transport_common.c |  29 +++---
 tools/testing/vsock/vsock_test.c        | 118 ++++++++++++++++++++++++
 2 files changed, 131 insertions(+), 16 deletions(-)

Patch

diff --git a/tools/testing/vsock/vsock_test.c b/tools/testing/vsock/vsock_test.c
index 67e9f9df3a8c..3de10dbb50f5 100644
--- a/tools/testing/vsock/vsock_test.c
+++ b/tools/testing/vsock/vsock_test.c
@@ -860,6 +860,114 @@  static void test_stream_poll_rcvlowat_client(const struct test_opts *opts)
 	close(fd);
 }
 
+#define INV_BUF_TEST_DATA_LEN 512
+
+static void test_inv_buf_client(const struct test_opts *opts, bool stream)
+{
+	unsigned char data[INV_BUF_TEST_DATA_LEN] = {0};
+	ssize_t ret;
+	int fd;
+
+	if (stream)
+		fd = vsock_stream_connect(opts->peer_cid, 1234);
+	else
+		fd = vsock_seqpacket_connect(opts->peer_cid, 1234);
+
+	if (fd < 0) {
+		perror("connect");
+		exit(EXIT_FAILURE);
+	}
+
+	control_expectln("SENDDONE");
+
+	/* Use invalid buffer here. */
+	ret = recv(fd, NULL, sizeof(data), 0);
+	if (ret != -1) {
+		fprintf(stderr, "expected recv(2) failure, got %zi\n", ret);
+		exit(EXIT_FAILURE);
+	}
+
+	if (errno != ENOMEM) {
+		fprintf(stderr, "unexpected recv(2) errno %d\n", errno);
+		exit(EXIT_FAILURE);
+	}
+
+	ret = recv(fd, data, sizeof(data), MSG_DONTWAIT);
+
+	if (stream) {
+		/* For SOCK_STREAM we must continue reading. */
+		if (ret != sizeof(data)) {
+			fprintf(stderr, "expected recv(2) success, got %zi\n", ret);
+			exit(EXIT_FAILURE);
+		}
+		/* Don't check errno in case of success. */
+	} else {
+		/* For SOCK_SEQPACKET socket's queue must be empty. */
+		if (ret != -1) {
+			fprintf(stderr, "expected recv(2) failure, got %zi\n", ret);
+			exit(EXIT_FAILURE);
+		}
+
+		if (errno != EAGAIN) {
+			fprintf(stderr, "unexpected recv(2) errno %d\n", errno);
+			exit(EXIT_FAILURE);
+		}
+	}
+
+	control_writeln("DONE");
+
+	close(fd);
+}
+
+static void test_inv_buf_server(const struct test_opts *opts, bool stream)
+{
+	unsigned char data[INV_BUF_TEST_DATA_LEN] = {0};
+	ssize_t res;
+	int fd;
+
+	if (stream)
+		fd = vsock_stream_accept(VMADDR_CID_ANY, 1234, NULL);
+	else
+		fd = vsock_seqpacket_accept(VMADDR_CID_ANY, 1234, NULL);
+
+	if (fd < 0) {
+		perror("accept");
+		exit(EXIT_FAILURE);
+	}
+
+	res = send(fd, data, sizeof(data), 0);
+	if (res != sizeof(data)) {
+		fprintf(stderr, "unexpected send(2) result %zi\n", res);
+		exit(EXIT_FAILURE);
+	}
+
+	control_writeln("SENDDONE");
+
+	control_expectln("DONE");
+
+	close(fd);
+}
+
+static void test_stream_inv_buf_client(const struct test_opts *opts)
+{
+	test_inv_buf_client(opts, true);
+}
+
+static void test_stream_inv_buf_server(const struct test_opts *opts)
+{
+	test_inv_buf_server(opts, true);
+}
+
+static void test_seqpacket_inv_buf_client(const struct test_opts *opts)
+{
+	test_inv_buf_client(opts, false);
+}
+
+static void test_seqpacket_inv_buf_server(const struct test_opts *opts)
+{
+	test_inv_buf_server(opts, false);
+}
+
 static struct test_case test_cases[] = {
 	{
 		.name = "SOCK_STREAM connection reset",
@@ -920,6 +1028,16 @@  static struct test_case test_cases[] = {
 		.run_client = test_seqpacket_bigmsg_client,
 		.run_server = test_seqpacket_bigmsg_server,
 	},
+	{
+		.name = "SOCK_STREAM test invalid buffer",
+		.run_client = test_stream_inv_buf_client,
+		.run_server = test_stream_inv_buf_server,
+	},
+	{
+		.name = "SOCK_SEQPACKET test invalid buffer",
+		.run_client = test_seqpacket_inv_buf_client,
+		.run_server = test_seqpacket_inv_buf_server,
+	},
 	{},
 };