From: "H.J. Lu" <hjl.tools@gmail.com>
To: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: GNU C Library <libc-alpha@sourceware.org>,
Florian Weimer <fweimer@redhat.com>
Subject: Re: [PATCH v6 3/3] Linux: Only generate 64 bit timestamps for 64 bit time_t recvmsg/recvmmsg
Date: Fri, 28 Jan 2022 20:51:58 -0800 [thread overview]
Message-ID: <CAMe9rOoqOeyuNjWEgiwTpWpqsVYtfFoebeV-xA-VmU4H2R=dhw@mail.gmail.com> (raw)
In-Reply-To: <20220128175043.161446-4-adhemerval.zanella@linaro.org>
On Fri, Jan 28, 2022 at 9:57 AM Adhemerval Zanella via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> The timestamps created by __convert_scm_timestamps only make sense for
> 64 bit time_t programs, 32 bit time_t programs will ignore 64 bit time_t
> timestamps since SO_TIMESTAMP will be defined to old values (either by
> glibc or kernel headers).
>
> Worse, if the buffer is not suffice MSG_CTRUNC is set to indicate it
> (which breaks some programs [1]).
>
> This patch makes only 64 bit time_t recvmsg and recvmmsg to call
> __convert_scm_timestamps. Also, the assumption to called it is changed
> from __ASSUME_TIME64_SYSCALLS to __TIMESIZE != 64 since the setsockopt
> might be called by libraries built without __TIME_BITS=64. The
> MSG_CTRUNC is only set for the 64 bit symbols, it should happen only
> if 64 bit time_t programs run older kernels.
>
> Checked on x86_64-linux-gnu and i686-linux-gnu.
>
> [1] https://github.com/systemd/systemd/pull/20567
> ---
> include/sys/socket.h | 10 +-
> sysdeps/unix/sysv/linux/Makefile | 10 +-
> sysdeps/unix/sysv/linux/recvmmsg.c | 45 ++-
> sysdeps/unix/sysv/linux/recvmsg.c | 34 ++-
> .../tst-socket-timestamp-compat-time64.c | 1 +
> .../sysv/linux/tst-socket-timestamp-compat.c | 265 ++++++++++++++++++
> 6 files changed, 336 insertions(+), 29 deletions(-)
> create mode 100644 sysdeps/unix/sysv/linux/tst-socket-timestamp-compat-time64.c
> create mode 100644 sysdeps/unix/sysv/linux/tst-socket-timestamp-compat.c
>
> diff --git a/include/sys/socket.h b/include/sys/socket.h
> index a1d749f9fa..6e4cf5077f 100644
> --- a/include/sys/socket.h
> +++ b/include/sys/socket.h
> @@ -98,15 +98,21 @@ extern int __sendmmsg (int __fd, struct mmsghdr *__vmessages,
> libc_hidden_proto (__sendmmsg)
> #endif
>
> -/* Receive a message as described by MESSAGE from socket FD.
> - Returns the number of bytes read or -1 for errors. */
> extern ssize_t __libc_recvmsg (int __fd, struct msghdr *__message,
> int __flags);
> extern ssize_t __recvmsg (int __fd, struct msghdr *__message,
> int __flags) attribute_hidden;
> #if __TIMESIZE == 64
> +# define __libc_recvmsg64 __libc_recvmsg
> +# define __recvmsg64 __recvmsg
> # define __recvmmsg64 __recvmmsg
> #else
> +extern ssize_t __libc_recvmsg64 (int __fd, struct msghdr *__message,
> + int __flags);
> +extern ssize_t __recvmsg64 (int __fd, struct msghdr *__message,
> + int __flags);
> +/* Receive a message as described by MESSAGE from socket FD.
> + Returns the number of bytes read or -1 for errors. */
> extern int __recvmmsg64 (int __fd, struct mmsghdr *vmessages,
> unsigned int vlen, int flags,
> struct __timespec64 *timeout);
> diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
> index 4c80ff809c..7122f55975 100644
> --- a/sysdeps/unix/sysv/linux/Makefile
> +++ b/sysdeps/unix/sysv/linux/Makefile
> @@ -277,8 +277,14 @@ sysdep_routines += cmsg_nxthdr
> CFLAGS-recvmmsg.c = -fexceptions -fasynchronous-unwind-tables
> CFLAGS-sendmmsg.c = -fexceptions -fasynchronous-unwind-tables
>
> -tests += tst-socket-timestamp
> -tests-time64 += tst-socket-timestamp-time64
> +tests += \
> + tst-socket-timestamp \
> + tst-socket-timestamp-compat \
> + # tests
> +tests-time64 += \
> + tst-socket-timestamp-time64 \
> + tst-socket-timestamp-compat-time64
> + # tests-time64
>
> tests-special += $(objpfx)tst-socket-consts.out
> $(objpfx)tst-socket-consts.out: ../sysdeps/unix/sysv/linux/tst-socket-consts.py
> diff --git a/sysdeps/unix/sysv/linux/recvmmsg.c b/sysdeps/unix/sysv/linux/recvmmsg.c
> index 3b9b5f9d1f..1943b9b3d4 100644
> --- a/sysdeps/unix/sysv/linux/recvmmsg.c
> +++ b/sysdeps/unix/sysv/linux/recvmmsg.c
> @@ -19,9 +19,9 @@
> #include <sysdep.h>
> #include <socketcall.h>
>
> -int
> -__recvmmsg64 (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags,
> - struct __timespec64 *timeout)
> +static int
> +recvmmsg_syscall (int fd, struct mmsghdr *vmessages, unsigned int vlen,
> + int flags, struct __timespec64 *timeout)
> {
> #ifndef __NR_recvmmsg_time64
> # define __NR_recvmmsg_time64 __NR_recvmmsg
> @@ -44,12 +44,6 @@ __recvmmsg64 (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags,
> pts32 = &ts32;
> }
>
> - socklen_t csize[IOV_MAX];
> - if (vlen > IOV_MAX)
> - vlen = IOV_MAX;
> - for (int i = 0; i < vlen; i++)
> - csize[i] = vmessages[i].msg_hdr.msg_controllen;
> -
> # ifdef __ASSUME_RECVMMSG_SYSCALL
> r = SYSCALL_CANCEL (recvmmsg, fd, vmessages, vlen, flags, pts32);
> # else
> @@ -59,11 +53,31 @@ __recvmmsg64 (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags,
> {
> if (timeout != NULL)
> *timeout = valid_timespec_to_timespec64 (ts32);
> + }
> +#endif
> + return r;
> +}
> +
> +int
> +__recvmmsg64 (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags,
> + struct __timespec64 *timeout)
> +{
> +#if __TIMESIZE != 64
> + socklen_t csize[IOV_MAX];
> + if (vlen > IOV_MAX)
> + vlen = IOV_MAX;
> + for (int i = 0; i < vlen; i++)
> + csize[i] = vmessages[i].msg_hdr.msg_controllen;
> +#endif
>
> + int r = recvmmsg_syscall (fd, vmessages, vlen, flags, timeout);
> +#if __TIMESIZE != 64
> + if (r > 0)
> + {
> for (int i=0; i < r; i++)
> __convert_scm_timestamps (&vmessages[i].msg_hdr, csize[i]);
> }
> -#endif /* __ASSUME_TIME64_SYSCALLS */
> +#endif
> return r;
> }
> #if __TIMESIZE != 64
> @@ -79,10 +93,13 @@ __recvmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags,
> ts64 = valid_timespec_to_timespec64 (*timeout);
> pts64 = &ts64;
> }
> - int r = __recvmmsg64 (fd, vmessages, vlen, flags, pts64);
> - if (r >= 0 && timeout != NULL)
> - /* The remanining timeout will be always less the input TIMEOUT. */
> - *timeout = valid_timespec64_to_timespec (ts64);
> + int r = recvmmsg_syscall (fd, vmessages, vlen, flags, pts64);
> + if (r >= 0)
> + {
> + /* The remanining timeout will be always less the input TIMEOUT. */
> + if (timeout != NULL)
> + *timeout = valid_timespec64_to_timespec (ts64);
> + }
> return r;
> }
> #endif
> diff --git a/sysdeps/unix/sysv/linux/recvmsg.c b/sysdeps/unix/sysv/linux/recvmsg.c
> index 53e567ed31..401d415b2c 100644
> --- a/sysdeps/unix/sysv/linux/recvmsg.c
> +++ b/sysdeps/unix/sysv/linux/recvmsg.c
> @@ -20,29 +20,41 @@
> #include <sysdep-cancel.h>
> #include <socketcall.h>
>
> +static int
> +__recvmsg_syscall (int fd, struct msghdr *msg, int flags)
> +{
> +#ifdef __ASSUME_RECVMSG_SYSCALL
> + return SYSCALL_CANCEL (recvmsg, fd, msg, flags);
> +#else
> + return SOCKETCALL_CANCEL (recvmsg, fd, msg, flags);
> +#endif
> +}
> +
> ssize_t
> -__libc_recvmsg (int fd, struct msghdr *msg, int flags)
> +__libc_recvmsg64 (int fd, struct msghdr *msg, int flags)
> {
> ssize_t r;
> -#ifndef __ASSUME_TIME64_SYSCALLS
> +#if __TIMESIZE != 64
> socklen_t orig_controllen = msg != NULL ? msg->msg_controllen : 0;
> #endif
>
> -#ifdef __ASSUME_RECVMSG_SYSCALL
> - r = SYSCALL_CANCEL (recvmsg, fd, msg, flags);
> -#else
> - r = SOCKETCALL_CANCEL (recvmsg, fd, msg, flags);
> -#endif
> + r = __recvmsg_syscall (fd, msg, flags);
>
> -#ifndef __ASSUME_TIME64_SYSCALLS
> +#if __TIMESIZE != 64
> if (r >= 0 && orig_controllen != 0)
> __convert_scm_timestamps (msg, orig_controllen);
> #endif
>
> return r;
> }
> -weak_alias (__libc_recvmsg, recvmsg)
> -weak_alias (__libc_recvmsg, __recvmsg)
> #if __TIMESIZE != 64
> -weak_alias (__recvmsg, __recvmsg64)
> +weak_alias (__libc_recvmsg64, __recvmsg64)
> +
> +ssize_t
> +__libc_recvmsg (int fd, struct msghdr *msg, int flags)
> +{
> + return __recvmsg_syscall (fd, msg, flags);
> +}
> #endif
> +weak_alias (__libc_recvmsg, recvmsg)
> +weak_alias (__libc_recvmsg, __recvmsg)
> diff --git a/sysdeps/unix/sysv/linux/tst-socket-timestamp-compat-time64.c b/sysdeps/unix/sysv/linux/tst-socket-timestamp-compat-time64.c
> new file mode 100644
> index 0000000000..96a0bef0bf
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/tst-socket-timestamp-compat-time64.c
> @@ -0,0 +1 @@
> +#include "tst-socket-timestamp-compat.c"
> diff --git a/sysdeps/unix/sysv/linux/tst-socket-timestamp-compat.c b/sysdeps/unix/sysv/linux/tst-socket-timestamp-compat.c
> new file mode 100644
> index 0000000000..de261dae5a
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/tst-socket-timestamp-compat.c
> @@ -0,0 +1,265 @@
> +/* Check recvmsg/recvmmsg 64-bit timestamp support.
> + Copyright (C) 2022 Free Software Foundation, Inc.
> + This file is part of the GNU C Library.
> +
> + The GNU C Library is free software; you can redistribute it and/or
> + modify it under the terms of the GNU Lesser General Public
> + License as published by the Free Software Foundation; either
> + version 2.1 of the License, or (at your option) any later version.
> +
> + The GNU C Library is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + Lesser General Public License for more details.
> +
> + You should have received a copy of the GNU Lesser General Public
> + License along with the GNU C Library; if not, see
> + <https://www.gnu.org/licenses/>. */
> +
> +#include <arpa/inet.h>
> +#include <string.h>
> +#include <support/check.h>
> +#include <support/xsocket.h>
> +#include <support/xunistd.h>
> +#include <stdbool.h>
> +
> +/* AF_INET socket and address used to receive data. */
> +static int srv;
> +static struct sockaddr_in srv_addr;
> +
> +static int
> +do_sendto (const struct sockaddr_in *addr, int payload)
> +{
> + int s = xsocket (AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0);
> + xconnect (s, (const struct sockaddr *) addr, sizeof (*addr));
> +
> + xsendto (s, &payload, sizeof (payload), 0, (const struct sockaddr *) addr,
> + sizeof (*addr));
> +
> + xclose (s);
> +
> + return 0;
> +}
> +
> +static void
> +do_recvmsg_ancillary (bool use_multi_call, struct mmsghdr *mmhdr,
> + void *msgbuf, size_t msgbuflen, int exp_payload)
> +{
> + int payload;
> + struct iovec iov =
> + {
> + .iov_base = &payload,
> + .iov_len = sizeof (payload)
> + };
> + mmhdr->msg_hdr.msg_name = NULL;
> + mmhdr->msg_hdr.msg_iov = &iov;
> + mmhdr->msg_hdr.msg_iovlen = 1;
> + mmhdr->msg_hdr.msg_control = msgbuf;
> + mmhdr->msg_hdr.msg_controllen = msgbuflen;
> +
> + int r;
> + if (use_multi_call)
> + {
> + r = recvmmsg (srv, mmhdr, 1, 0, NULL);
> + if (r >= 0)
> + r = mmhdr->msg_len;
> + }
> + else
> + r = recvmsg (srv, &mmhdr->msg_hdr, 0);
> + TEST_COMPARE (r, sizeof (int));
> + TEST_COMPARE (payload, exp_payload);
> +}
> +
> +/* Check if recvmsg create the additional 64 bit timestamp if only 32 bit
> + is enabled for 64 bit recvmsg symbol. */
> +static void
> +do_test_large_buffer (bool mc)
> +{
> + struct mmsghdr mmhdr = { 0 };
> + /* It should be large enought for either timeval/timespec and the
> + 64 time type as well. */
> +
> + union
> + {
> + struct cmsghdr cmsghdr;
> + char msgbuf[512];
> + } control;
> +
> + /* Enable 32 bit timeval precision and check if no 64 bit timeval stamp
> + is created. */
> + {
> + int r = setsockopt (srv, SOL_SOCKET, SO_TIMESTAMP_OLD, &(int){1},
> + sizeof (int));
> + TEST_VERIFY_EXIT (r != -1);
> +
> + do_sendto (&srv_addr, 42);
> + do_recvmsg_ancillary (mc, &mmhdr, &control, sizeof control, 42);
> +
> + bool found_timestamp = false;
> + for (struct cmsghdr *cmsg = CMSG_FIRSTHDR (&mmhdr.msg_hdr);
> + cmsg != NULL;
> + cmsg = CMSG_NXTHDR (&mmhdr.msg_hdr, cmsg))
> + {
> + if (cmsg->cmsg_level != SOL_SOCKET)
> + continue;
> +
> + if (sizeof (time_t) > 4 && cmsg->cmsg_type == SO_TIMESTAMP_NEW)
> + found_timestamp = true;
> + else
> + TEST_VERIFY (cmsg->cmsg_type != SO_TIMESTAMP_NEW);
> + }
> +
> + TEST_COMPARE (found_timestamp, sizeof (time_t) > 4);
> + }
> +
> + /* Same as before, but for timespec. */
> + {
> + int r = setsockopt (srv, SOL_SOCKET, SO_TIMESTAMPNS_OLD, &(int){1},
> + sizeof (int));
> + TEST_VERIFY_EXIT (r != -1);
> +
> + do_sendto (&srv_addr, 42);
> + do_recvmsg_ancillary (mc, &mmhdr, &control, sizeof control, 42);
> +
> + bool found_timestamp = false;
> + for (struct cmsghdr *cmsg = CMSG_FIRSTHDR (&mmhdr.msg_hdr);
> + cmsg != NULL;
> + cmsg = CMSG_NXTHDR (&mmhdr.msg_hdr, cmsg))
> + {
> + if (cmsg->cmsg_level != SOL_SOCKET)
> + continue;
> +
> + if (sizeof (time_t) > 4 && cmsg->cmsg_type == SO_TIMESTAMPNS_NEW)
> + found_timestamp = true;
> + else
> + TEST_VERIFY (cmsg->cmsg_type != SO_TIMESTAMPNS_NEW);
> + }
> +
> + TEST_COMPARE (found_timestamp, sizeof (time_t) > 4);
> + }
> +}
> +
> +/* Check if recvmsg does not create the additional 64 bit timestamp if
> + only 32 bit timestamp is enabled if the ancillary buffer is not large
> + enought. Also checks if MSG_CTRUNC is set iff for 64 bit recvmsg
> + symbol. */
> +static void
> +do_test_small_buffer (bool mc)
> +{
> + struct mmsghdr mmhdr = { 0 };
> +
> + /* Enable 32 bit timeval precision and check if no 64 bit timeval stamp
> + is created. */
> + {
> + int r = setsockopt (srv, SOL_SOCKET, SO_TIMESTAMP_OLD, &(int){1},
> + sizeof (int));
> + TEST_VERIFY_EXIT (r != -1);
> +
> + union
> + {
> + struct cmsghdr cmsghdr;
> + char msgbuf[CMSG_SPACE (sizeof (struct timeval))];
> + } control;
> +
> + do_sendto (&srv_addr, 42);
> + do_recvmsg_ancillary (mc, &mmhdr, &control, sizeof control, 42);
> +
> + bool found_timestamp = false;
> + for (struct cmsghdr *cmsg = CMSG_FIRSTHDR (&mmhdr.msg_hdr);
> + cmsg != NULL;
> + cmsg = CMSG_NXTHDR (&mmhdr.msg_hdr, cmsg))
> + {
> + if (cmsg->cmsg_level != SOL_SOCKET)
> + continue;
> +
> + if (sizeof (time_t) > 4 && cmsg->cmsg_type == SO_TIMESTAMP_NEW)
> + found_timestamp = true;
> + else
> + TEST_VERIFY (cmsg->cmsg_type != SO_TIMESTAMP_NEW);
> + }
> +
> + if (sizeof (time_t) > 4)
> + {
> + TEST_VERIFY ((mmhdr.msg_hdr.msg_flags & MSG_CTRUNC));
> + TEST_COMPARE (found_timestamp, 0);
> + }
> + else
> + {
> + TEST_VERIFY (!(mmhdr.msg_hdr.msg_flags & MSG_CTRUNC));
> + TEST_COMPARE (found_timestamp, 0);
> + }
> + }
> +
> + /* Same as before, but for timespec. */
> + {
> + int r = setsockopt (srv, SOL_SOCKET, SO_TIMESTAMPNS_OLD, &(int){1},
> + sizeof (int));
> + TEST_VERIFY_EXIT (r != -1);
> +
> + union
> + {
> + struct cmsghdr cmsghdr;
> + char msgbuf[CMSG_SPACE (sizeof (struct timespec))];
> + } control;
> +
> + do_sendto (&srv_addr, 42);
> + do_recvmsg_ancillary (mc, &mmhdr, &control, sizeof control, 42);
> +
> + bool found_timestamp = false;
> + for (struct cmsghdr *cmsg = CMSG_FIRSTHDR (&mmhdr.msg_hdr);
> + cmsg != NULL;
> + cmsg = CMSG_NXTHDR (&mmhdr.msg_hdr, cmsg))
> + {
> + if (cmsg->cmsg_level != SOL_SOCKET)
> + continue;
> +
> + if (sizeof (time_t) > 4 && cmsg->cmsg_type == SO_TIMESTAMPNS_NEW)
> + found_timestamp = true;
> + else
> + TEST_VERIFY (cmsg->cmsg_type != SO_TIMESTAMPNS_NEW);
> + }
> +
> + if (sizeof (time_t) > 4)
> + {
> + TEST_VERIFY ((mmhdr.msg_hdr.msg_flags & MSG_CTRUNC));
> + TEST_COMPARE (found_timestamp, 0);
> + }
> + else
> + {
> + TEST_VERIFY ((mmhdr.msg_hdr.msg_flags & MSG_CTRUNC) == 0);
> + TEST_COMPARE (found_timestamp, 0);
> + }
> + }
> +}
> +
> +static int
> +do_test (void)
> +{
> + /* This test only make sense for ABIs that support 32 bit time_t socket
> + timestampss. */
> + if (sizeof (time_t) > 4 && __WORDSIZE == 64)
This is wrong for x32 which has 64-bit time_t from day one, but __WORDSIZE
is 32.
> + return 0;
> +
> + srv = xsocket (AF_INET, SOCK_DGRAM, 0);
> + srv_addr = (struct sockaddr_in) {
> + .sin_family = AF_INET,
> + .sin_addr = {.s_addr = htonl (INADDR_LOOPBACK) },
> + };
> + xbind (srv, (struct sockaddr *) &srv_addr, sizeof (srv_addr));
> + {
> + socklen_t sa_len = sizeof (srv_addr);
> + xgetsockname (srv, (struct sockaddr *) &srv_addr, &sa_len);
> + TEST_VERIFY (sa_len == sizeof (srv_addr));
> + }
> +
> + /* Check recvmsg; */
> + do_test_large_buffer (false);
> + do_test_small_buffer (false);
> + /* Check recvmmsg. */
> + do_test_large_buffer (true);
> + do_test_small_buffer (true);
> +
> + return 0;
> +}
> +
> +#include <support/test-driver.c>
> --
> 2.32.0
>
--
H.J.
next prev parent reply other threads:[~2022-01-29 4:52 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-28 17:50 [PATCH v6 0/3] Fix socket ancillary timestamp on 32 bit time_t ABIs Adhemerval Zanella
2022-01-28 17:50 ` [PATCH v6 1/3] support: Add support_socket_so_timestamp_time64 Adhemerval Zanella
2022-01-28 17:50 ` [PATCH v6 2/3] linux: Fix ancillary 64-bit time timestamp conversion (BZ #28349, BZ#28350) Adhemerval Zanella
2022-01-28 17:50 ` [PATCH v6 3/3] Linux: Only generate 64 bit timestamps for 64 bit time_t recvmsg/recvmmsg Adhemerval Zanella
2022-01-28 18:19 ` Florian Weimer
2022-01-28 19:41 ` Carlos O'Donell
2022-01-29 4:51 ` H.J. Lu [this message]
2022-02-03 18:34 ` Szabolcs Nagy
2022-02-03 18:36 ` Adhemerval Zanella
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