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107 lines
3.7 KiB
C
107 lines
3.7 KiB
C
/* Check recvmsg results for netlink sockets.
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Copyright (C) 2015-2025 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 <errno.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdbool.h>
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#include <sys/socket.h>
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#include "netlinkaccess.h"
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static int
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get_address_family (int fd)
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{
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struct sockaddr_storage sa;
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socklen_t sa_len = sizeof (sa);
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if (__getsockname (fd, (struct sockaddr *) &sa, &sa_len) < 0)
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return -1;
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/* Check that the socket family number is preserved despite in-band
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signaling. */
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_Static_assert (sizeof (sa.ss_family) < sizeof (int), "address family size");
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_Static_assert (0 < (__typeof__ (sa.ss_family)) -1,
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"address family unsigned");
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return sa.ss_family;
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}
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void
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__netlink_assert_response (int fd, ssize_t result)
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{
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if (result < 0)
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{
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/* Check if the error is unexpected. */
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bool terminate = false;
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int error_code = errno;
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int family = get_address_family (fd);
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if (family != AF_NETLINK)
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/* If the address family does not match (or getsockname
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failed), report the original error. */
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terminate = true;
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else if (error_code == EBADF
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|| error_code == ENOTCONN
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|| error_code == ENOTSOCK
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|| error_code == ECONNREFUSED)
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/* These errors indicate that the descriptor is not a
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connected socket. */
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terminate = true;
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else if (error_code == EAGAIN || error_code == EWOULDBLOCK)
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{
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/* The kernel might return EAGAIN for other reasons than a
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non-blocking socket. But if the socket is not blocking,
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it is not ours, so report the error. */
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int mode = __fcntl (fd, F_GETFL, 0);
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if (mode < 0 || (mode & O_NONBLOCK) != 0)
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terminate = true;
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}
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if (terminate)
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{
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char message[200];
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if (family < 0)
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__snprintf (message, sizeof (message),
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"Unexpected error %d on netlink descriptor %d.\n",
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error_code, fd);
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else
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__snprintf (message, sizeof (message),
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"Unexpected error %d on netlink descriptor %d"
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" (address family %d).\n",
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error_code, fd, family);
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__libc_fatal (message);
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}
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else
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/* Restore original errno value. */
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__set_errno (error_code);
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}
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else if (result < sizeof (struct nlmsghdr))
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{
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char message[200];
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int family = get_address_family (fd);
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if (family < 0)
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__snprintf (message, sizeof (message),
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"Unexpected netlink response of size %zd"
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" on descriptor %d\n",
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result, fd);
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else
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__snprintf (message, sizeof (message),
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"Unexpected netlink response of size %zd"
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" on descriptor %d (address family %d)\n",
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result, fd, family);
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__libc_fatal (message);
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}
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}
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libc_hidden_def (__netlink_assert_response)
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