git: adaf752192c1 - stable/13 - sockets: add MSG_TRUNC flag handling for recvfrom()/recvmsg().
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Date: Thu, 09 Feb 2023 18:01:56 UTC
The branch stable/13 has been updated by melifaro:
URL: https://cgit.FreeBSD.org/src/commit/?id=adaf752192c165b66875e81db62d274a09591d0c
commit adaf752192c165b66875e81db62d274a09591d0c
Author: Alexander V. Chernikov <melifaro@FreeBSD.org>
AuthorDate: 2022-07-25 19:46:40 +0000
Commit: Alexander V. Chernikov <melifaro@FreeBSD.org>
CommitDate: 2023-02-09 18:01:49 +0000
sockets: add MSG_TRUNC flag handling for recvfrom()/recvmsg().
Implement Linux-variant of MSG_TRUNC input flag used in recv(), recvfrom() and recvmsg().
Posix defines MSG_TRUNC as an output flag, indicating packet/datagram truncation.
Linux extended it a while (~15+ years) ago to act as input flag,
resulting in returning the full packet size regarless of the input
buffer size.
It's a (relatively) popular pattern to do recvmsg( MSG_PEEK | MSG_TRUNC) to get the
packet size, allocate the buffer and issue another call to fetch the packet.
In particular, it's popular in userland netlink code, which is the primary driving factor of this change.
This commit implements the MSG_TRUNC support for SOCK_DGRAM sockets (udp, unix and all soreceive_generic() users).
PR: kern/176322
Reviewed by: pauamma(doc)
Differential Revision: https://reviews.freebsd.org/D35909
MFC after: 1 month
(cherry picked from commit be1f485d7d6bebc53b055cc165a11ada0ab5fb17)
---
lib/libc/sys/recv.2 | 12 +++
sys/kern/uipc_socket.c | 13 ++-
tests/sys/kern/Makefile | 1 +
tests/sys/kern/socket_msg_trunc.c | 169 ++++++++++++++++++++++++++++++++++++++
4 files changed, 191 insertions(+), 4 deletions(-)
diff --git a/lib/libc/sys/recv.2 b/lib/libc/sys/recv.2
index 46e0cf8163dd..95a9e83446a0 100644
--- a/lib/libc/sys/recv.2
+++ b/lib/libc/sys/recv.2
@@ -163,6 +163,7 @@ one or more of the values:
.Bl -column ".Dv MSG_CMSG_CLOEXEC" -offset indent
.It Dv MSG_OOB Ta process out-of-band data
.It Dv MSG_PEEK Ta peek at incoming message
+.It Dv MSG_TRUNC Ta return real packet or datagram length
.It Dv MSG_WAITALL Ta wait for full request or error
.It Dv MSG_DONTWAIT Ta do not block
.It Dv MSG_CMSG_CLOEXEC Ta set received fds close-on-exec
@@ -185,6 +186,17 @@ from the beginning of the receive queue without removing that
data from the queue.
Thus, a subsequent receive call will return the same data.
The
+.Dv MSG_TRUNC
+flag causes the receive operation to return the full length of the packet
+or datagram even if larger than provided buffer. The flag is supported
+on SOCK_DGRAM sockets for
+.Dv AF_INET
+,
+.Dv AF_INET6
+and
+.Dv AF_UNIX
+families.
+The
.Dv MSG_WAITALL
flag requests that the operation block until
the full request is satisfied.
diff --git a/sys/kern/uipc_socket.c b/sys/kern/uipc_socket.c
index ce7279357fab..f8931b653a4d 100644
--- a/sys/kern/uipc_socket.c
+++ b/sys/kern/uipc_socket.c
@@ -1911,15 +1911,18 @@ soreceive_generic(struct socket *so, struct sockaddr **psa, struct uio *uio,
struct mbuf *nextrecord;
int moff, type = 0;
ssize_t orig_resid = uio->uio_resid;
+ bool report_real_len = false;
mp = mp0;
if (psa != NULL)
*psa = NULL;
if (controlp != NULL)
*controlp = NULL;
- if (flagsp != NULL)
+ if (flagsp != NULL) {
+ report_real_len = *flagsp & MSG_TRUNC;
+ *flagsp &= ~MSG_TRUNC;
flags = *flagsp &~ MSG_EOR;
- else
+ } else
flags = 0;
if (flags & MSG_OOB)
return (soreceive_rcvoob(so, uio, flags));
@@ -1993,7 +1996,7 @@ restart:
error = ENOTCONN;
goto release;
}
- if (uio->uio_resid == 0) {
+ if (uio->uio_resid == 0 && !report_real_len) {
SOCKBUF_UNLOCK(&so->so_rcv);
goto release;
}
@@ -2341,6 +2344,8 @@ dontblock:
SOCKBUF_LOCK_ASSERT(&so->so_rcv);
if (m != NULL && pr->pr_flags & PR_ATOMIC) {
+ if (report_real_len)
+ uio->uio_resid -= m_length(m, NULL) - moff;
flags |= MSG_TRUNC;
if ((flags & MSG_PEEK) == 0)
(void) sbdroprecord_locked(&so->so_rcv);
@@ -2639,7 +2644,7 @@ soreceive_dgram(struct socket *so, struct sockaddr **psa, struct uio *uio,
* For any complicated cases, fall back to the full
* soreceive_generic().
*/
- if (mp0 != NULL || (flags & MSG_PEEK) || (flags & MSG_OOB))
+ if (mp0 != NULL || (flags & (MSG_PEEK | MSG_OOB | MSG_TRUNC)))
return (soreceive_generic(so, psa, uio, mp0, controlp,
flagsp));
diff --git a/tests/sys/kern/Makefile b/tests/sys/kern/Makefile
index 0fda50f592a0..3f6043f19f88 100644
--- a/tests/sys/kern/Makefile
+++ b/tests/sys/kern/Makefile
@@ -25,6 +25,7 @@ ATF_TESTS_C+= reaper
ATF_TESTS_C+= sched_affinity
ATF_TESTS_C+= sigaltstack
ATF_TESTS_C+= sigwait
+ATF_TESTS_C+= socket_msg_trunc
TEST_METADATA.sigwait+= is_exclusive="true"
.if ${MACHINE_ARCH} != "i386" && ${MACHINE_ARCH:Mpowerpc*} == "" && \
${MACHINE_CPUARCH} != "mips"
diff --git a/tests/sys/kern/socket_msg_trunc.c b/tests/sys/kern/socket_msg_trunc.c
new file mode 100644
index 000000000000..5041842f32b7
--- /dev/null
+++ b/tests/sys/kern/socket_msg_trunc.c
@@ -0,0 +1,169 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2022 Alexander V. Chernikov
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/errno.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <netinet/in.h>
+#include <poll.h>
+
+#include <atf-c.h>
+
+static void
+check_recvmsg(const char *test_name)
+{
+ int ss, cs, rc;
+ struct sockaddr *sa;
+ struct sockaddr_in sin;
+ struct sockaddr_in6 sin6;
+ struct sockaddr_un saun;
+ int *sizes, sizes_count;
+ int one = 1;
+
+
+ if (!strcmp(test_name, "udp")) {
+ ss = socket(PF_INET, SOCK_DGRAM, 0);
+ ATF_CHECK(ss >= 0);
+ rc = setsockopt(ss, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(one));
+ ATF_CHECK_EQ(0, rc);
+ bzero(&sin, sizeof(sin));
+ sin.sin_family = AF_INET;
+ sin.sin_len = sizeof(sin);
+ sin.sin_port = htons(6666);
+ sin.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+ sa = (struct sockaddr *)&sin;
+ rc = bind(ss, sa, sa->sa_len);
+ ATF_CHECK_EQ(0, rc);
+
+ cs = socket(PF_INET, SOCK_DGRAM, 0);
+ ATF_CHECK(cs >= 0);
+ int inet_sizes[] = {80, 255, 256, 1024, 4096, 9000};
+ sizes_count = sizeof(inet_sizes) / sizeof(int);
+ sizes = malloc(sizeof(inet_sizes));
+ memcpy(sizes, inet_sizes, sizeof(inet_sizes));
+
+ } else if (!strcmp(test_name, "udp6")) {
+ ss = socket(PF_INET6, SOCK_DGRAM, 0);
+ ATF_CHECK(ss >= 0);
+ rc = setsockopt(ss, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(one));
+ ATF_CHECK_EQ(0, rc);
+ bzero(&sin6, sizeof(sin6));
+ sin6.sin6_family = AF_INET6;
+ sin6.sin6_len = sizeof(sin6);
+ sin6.sin6_port = htons(6666);
+ const struct in6_addr in6loopback = IN6ADDR_LOOPBACK_INIT;
+ sin6.sin6_addr = in6loopback;
+ sa = (struct sockaddr *)&sin6;
+ rc = bind(ss, sa, sa->sa_len);
+ ATF_CHECK_EQ(0, rc);
+
+ cs = socket(PF_INET6, SOCK_DGRAM, 0);
+ ATF_CHECK(cs >= 0);
+ int inet_sizes[] = {80, 255, 256, 1024, 4096, 9000};
+ sizes_count = sizeof(inet_sizes) / sizeof(int);
+ sizes = malloc(sizeof(inet_sizes));
+ memcpy(sizes, inet_sizes, sizeof(inet_sizes));
+
+ } else if (!strcmp(test_name, "unix")) {
+ const char *PATH = "/tmp/test_check_recvmsg_socket";
+ ss = socket(PF_UNIX, SOCK_DGRAM, 0);
+ ATF_CHECK(ss >= 0);
+ rc = setsockopt(ss, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(one));
+ ATF_CHECK_EQ(0, rc);
+ bzero(&saun, sizeof(saun));
+ saun.sun_family = AF_UNIX;
+ strcpy(saun.sun_path, PATH);
+ saun.sun_len = sizeof(saun);
+ sa = (struct sockaddr *)&saun;
+ unlink(PATH);
+ rc = bind(ss, sa, sa->sa_len);
+ ATF_CHECK_EQ(0, rc);
+
+ cs = socket(PF_UNIX, SOCK_DGRAM, 0);
+ ATF_CHECK(cs >= 0);
+ int unix_sizes[] = {80, 255, 256, 1024, 2000};
+ sizes_count = sizeof(unix_sizes) / sizeof(int);
+ sizes = malloc(sizeof(unix_sizes));
+ memcpy(sizes, unix_sizes, sizeof(unix_sizes));
+ } else
+ return;
+
+ char buf[4096];
+ memset(buf, 0xFF, sizeof(buf));
+ for (int i = 0; i < sizes_count; i++) {
+ int sz = sizes[i];
+ char tbuf[1];
+ rc = sendto(cs, buf, sz, 0, sa, sa->sa_len);
+ ATF_REQUIRE_EQ(rc, sz);
+
+ rc = recv(ss, NULL, 0, MSG_PEEK | MSG_TRUNC);
+ ATF_CHECK_EQ(rc, sz);
+
+ rc = recv(ss, tbuf, sizeof(tbuf), MSG_PEEK | MSG_TRUNC);
+ ATF_CHECK_EQ(rc, sz);
+
+ rc = recv(ss, tbuf, sizeof(tbuf), MSG_TRUNC);
+ ATF_CHECK_EQ(rc, sz);
+ }
+
+ close(ss);
+ close(cs);
+}
+
+ATF_TC_WITHOUT_HEAD(socket_afinet_udp_recv_trunc);
+ATF_TC_BODY(socket_afinet_udp_recv_trunc, tc)
+{
+ check_recvmsg("udp");
+}
+
+ATF_TC_WITHOUT_HEAD(socket_afinet6_udp_recv_trunc);
+ATF_TC_BODY(socket_afinet6_udp_recv_trunc, tc)
+{
+ check_recvmsg("udp6");
+}
+
+ATF_TC_WITHOUT_HEAD(socket_afunix_recv_trunc);
+ATF_TC_BODY(socket_afunix_recv_trunc, tc)
+{
+ check_recvmsg("unix");
+}
+
+
+ATF_TP_ADD_TCS(tp)
+{
+
+ ATF_TP_ADD_TC(tp, socket_afinet_udp_recv_trunc);
+ ATF_TP_ADD_TC(tp, socket_afinet6_udp_recv_trunc);
+ ATF_TP_ADD_TC(tp, socket_afunix_recv_trunc);
+
+ return atf_no_error();
+}