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13c51549e2
The recvmsg handling is more complicated because it requires check the returned kernel control message and make some convertions. For !__ASSUME_TIME64_SYSCALLS it converts the first 32-bit time SO_TIMESTAMP or SO_TIMESTAMPNS and appends it to the control buffer if has extra space or returns MSG_CTRUNC otherwise. The 32-bit time field is kept as-is. Calls with __TIMESIZE=32 will see the converted 64-bit time control messages as spurious control message of unknown type. Calls with __TIMESIZE=64 running on pre-time64 kernels will see the original message as a spurious control ones of unknown typ while running on kernel with native 64-bit time support will only see the time64 version of the control message. Checked on x86_64-linux-gnu and i686-linux-gnu (on 5.4 and on 4.15 kernel). Reviewed-by: Carlos O'Donell <carlos@redhat.com> Tested-by: Carlos O'Donell <carlos@redhat.com>
96 lines
2.8 KiB
C
96 lines
2.8 KiB
C
/* Socket timestamp conversion routines.
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Copyright (C) 2021 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <kernel-features.h>
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#ifndef __ASSUME_TIME64_SYSCALLS
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# include <stdint.h>
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# include <string.h>
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# include <sys/socket.h>
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# include <socket-constants-time64.h>
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/* It converts the first SO_TIMESTAMP or SO_TIMESTAMPNS with 32-bit time and
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appends it to the control buffer. The 32-bit time field is kept as-is.
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Calls with __TIMESIZE=32 will see the converted 64-bit time control
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messages as spurious control message of unknown type.
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Calls with __TIMESIZE=64 running on pre-time64 kernels will see the
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original message as a spurious control ones of unknown typ while running
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on kernel with native 64-bit time support will only see the time64 version
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of the control message. */
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void
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__convert_scm_timestamps (struct msghdr *msg, socklen_t msgsize)
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{
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if (msg->msg_control == NULL || msg->msg_controllen == 0)
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return;
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/* The returned control message format for SO_TIMESTAMP_NEW is a
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'struct __kernel_sock_timeval' while for SO_TIMESTAMPNS_NEW is a
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'struct __kernel_timespec'. In either case it is two uint64_t
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members. */
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uint64_t tvts[2];
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struct cmsghdr *cmsg, *last = NULL;
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int type = 0;
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for (cmsg = CMSG_FIRSTHDR (msg);
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cmsg != NULL;
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cmsg = CMSG_NXTHDR (msg, cmsg))
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{
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if (cmsg->cmsg_level != SOL_SOCKET)
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continue;
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switch (cmsg->cmsg_type)
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{
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case COMPAT_SO_TIMESTAMP_OLD:
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if (type != 0)
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break;
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type = COMPAT_SO_TIMESTAMP_NEW;
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goto common;
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case COMPAT_SO_TIMESTAMPNS_OLD:
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type = COMPAT_SO_TIMESTAMPNS_NEW;
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/* fallthrough */
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common:
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memcpy (tvts, CMSG_DATA (cmsg), sizeof (tvts));
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break;
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}
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last = cmsg;
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}
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if (last == NULL || type == 0)
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return;
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if (CMSG_SPACE (sizeof tvts) > msgsize - msg->msg_controllen)
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{
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msg->msg_flags |= MSG_CTRUNC;
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return;
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}
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msg->msg_controllen += CMSG_SPACE (sizeof tvts);
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cmsg = CMSG_NXTHDR(msg, last);
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cmsg->cmsg_level = SOL_SOCKET;
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cmsg->cmsg_type = type;
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cmsg->cmsg_len = CMSG_LEN (sizeof tvts);
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memcpy (CMSG_DATA (cmsg), tvts, sizeof tvts);
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}
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#endif
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