netlink: decode NLMSG_ERROR messages
* netlink.c (decode_nlmsgerr, decode_payload): New functions. (decode_nlmsghdr_with_payload): Use decode_payload. * tests/netlink_protocol.c (send_query): Check decoding of NLMSG_ERROR messages. * NEWS: Mention this change.
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1
NEWS
1
NEWS
@ -20,6 +20,7 @@ Noteworthy changes in release ?.?? (????-??-??)
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* Implemented decoding of statx syscall.
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* Implemented decoding of NS_* ioctl commands.
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* Implemented decoding of the remaining V4L2_BUF_TYPE_* types.
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* Implemented decoding of NLMSG_ERROR netlink messages.
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* Updated lists of ioctl commands from Linux 4.11.
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* Bug fixes
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54
netlink.c
54
netlink.c
@ -69,6 +69,55 @@ print_nlmsghdr(struct tcb *tcp, const struct nlmsghdr *const nlmsghdr)
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nlmsghdr->nlmsg_pid);
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}
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static void
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decode_nlmsghdr_with_payload(struct tcb *const tcp,
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const struct nlmsghdr *const nlmsghdr,
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const kernel_ulong_t addr,
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const kernel_ulong_t len);
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static void
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decode_nlmsgerr(struct tcb *const tcp,
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kernel_ulong_t addr,
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kernel_ulong_t len)
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{
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struct nlmsgerr err;
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if (umove_or_printaddr(tcp, addr, &err.error))
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return;
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tprints("{error=");
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if (err.error < 0 && (unsigned) -err.error < nerrnos) {
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tprintf("-%s", errnoent[-err.error]);
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} else {
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tprintf("%d", err.error);
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}
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addr += offsetof(struct nlmsgerr, msg);
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len -= offsetof(struct nlmsgerr, msg);
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if (len) {
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tprints(", msg=");
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if (fetch_nlmsghdr(tcp, &err.msg, addr, len)) {
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decode_nlmsghdr_with_payload(tcp, &err.msg, addr, len);
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}
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}
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tprints("}");
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}
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static void
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decode_payload(struct tcb *const tcp,
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const struct nlmsghdr *const nlmsghdr,
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const kernel_ulong_t addr,
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const kernel_ulong_t len)
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{
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if (nlmsghdr->nlmsg_type == NLMSG_ERROR && len >= sizeof(int)) {
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decode_nlmsgerr(tcp, addr, len);
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} else {
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printstrn(tcp, addr, len);
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}
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}
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static void
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decode_nlmsghdr_with_payload(struct tcb *const tcp,
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const struct nlmsghdr *const nlmsghdr,
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@ -83,9 +132,8 @@ decode_nlmsghdr_with_payload(struct tcb *const tcp,
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nlmsghdr->nlmsg_len > len ? len : nlmsghdr->nlmsg_len;
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if (nlmsg_len > NLMSG_HDRLEN) {
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tprints(", ");
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printstrn(tcp, addr + NLMSG_HDRLEN,
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nlmsg_len - NLMSG_HDRLEN);
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decode_payload(tcp, nlmsghdr, addr + NLMSG_HDRLEN,
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nlmsg_len - NLMSG_HDRLEN);
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}
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tprints("}");
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@ -1,7 +1,7 @@
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/*
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* Check decoding of netlink protocol.
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*
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* Copyright (c) 2014-2016 Dmitry V. Levin <ldv@altlinux.org>
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* Copyright (c) 2014-2017 Dmitry V. Levin <ldv@altlinux.org>
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* Copyright (c) 2016 Fabien Siron <fabien.siron@epita.fr>
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* All rights reserved.
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*
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@ -199,6 +199,124 @@ send_query(const int fd)
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printf(", ...], %u, MSG_DONTWAIT, NULL, 0) = %s\n", msg_len, errstr);
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}
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static void
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test_nlmsgerr(const int fd)
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{
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struct nlmsgerr *err;
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struct nlmsghdr *nlh;
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void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
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long rc;
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/* error message without enough room for the error code */
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nlh = nlh0;
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nlh->nlmsg_len = NLMSG_HDRLEN + 4;
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nlh->nlmsg_type = NLMSG_ERROR;
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nlh->nlmsg_flags = NLM_F_REQUEST;
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nlh->nlmsg_seq = 0;
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nlh->nlmsg_pid = 0;
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rc = sendto(fd, nlh, nlh->nlmsg_len, MSG_DONTWAIT, NULL, 0);
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printf("sendto(%d, {{len=%u, type=NLMSG_ERROR, flags=NLM_F_REQUEST"
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", seq=0, pid=0}, %p}, %u, MSG_DONTWAIT, NULL, 0) = %s\n",
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fd, nlh->nlmsg_len, nlh0 + NLMSG_HDRLEN,
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nlh->nlmsg_len, sprintrc(rc));
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nlh = nlh0 - 2;
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nlh->nlmsg_len = NLMSG_HDRLEN + 2;
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nlh->nlmsg_type = NLMSG_ERROR;
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nlh->nlmsg_flags = NLM_F_REQUEST;
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nlh->nlmsg_seq = 0;
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nlh->nlmsg_pid = 0;
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memcpy(NLMSG_DATA(nlh), "42", 2);
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rc = sendto(fd, nlh, nlh->nlmsg_len, MSG_DONTWAIT, NULL, 0);
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printf("sendto(%d, {{len=%u, type=NLMSG_ERROR, flags=NLM_F_REQUEST"
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", seq=0, pid=0}, \"42\"}, %u, MSG_DONTWAIT, NULL, 0) = %s\n",
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fd, nlh->nlmsg_len, nlh->nlmsg_len, sprintrc(rc));
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/* error message with room for the error code only */
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nlh = nlh0 - sizeof(err->error);
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nlh->nlmsg_len = NLMSG_HDRLEN + sizeof(err->error);
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nlh->nlmsg_type = NLMSG_ERROR;
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nlh->nlmsg_flags = NLM_F_REQUEST;
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nlh->nlmsg_seq = 0;
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nlh->nlmsg_pid = 0;
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err = NLMSG_DATA(nlh);
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err->error = 42;
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rc = sendto(fd, nlh, nlh->nlmsg_len, MSG_DONTWAIT, NULL, 0);
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printf("sendto(%d, {{len=%u, type=NLMSG_ERROR, flags=NLM_F_REQUEST"
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", seq=0, pid=0}, {error=42}}, %u, MSG_DONTWAIT, NULL, 0)"
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" = %s\n", fd, nlh->nlmsg_len, nlh->nlmsg_len, sprintrc(rc));
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err->error = -1;
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rc = sendto(fd, nlh, nlh->nlmsg_len, MSG_DONTWAIT, NULL, 0);
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printf("sendto(%d, {{len=%u, type=NLMSG_ERROR, flags=NLM_F_REQUEST"
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", seq=0, pid=0}, {error=-EPERM}}, %u, MSG_DONTWAIT, NULL, 0)"
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" = %s\n", fd, nlh->nlmsg_len, nlh->nlmsg_len, sprintrc(rc));
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err->error = -32767;
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nlh->nlmsg_len += sizeof(err->msg.nlmsg_len);
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rc = sendto(fd, nlh, nlh->nlmsg_len, MSG_DONTWAIT, NULL, 0);
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printf("sendto(%d, {{len=%u, type=NLMSG_ERROR, flags=NLM_F_REQUEST"
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", seq=0, pid=0}, {error=-32767, msg=%p}}"
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", %u, MSG_DONTWAIT, NULL, 0) = %s\n",
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fd, nlh->nlmsg_len, nlh0 + NLMSG_HDRLEN,
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nlh->nlmsg_len, sprintrc(rc));
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/* error message with room for the error code and a header */
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nlh = nlh0 - sizeof(*err);
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nlh->nlmsg_len = NLMSG_HDRLEN + sizeof(*err);
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nlh->nlmsg_type = NLMSG_ERROR;
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nlh->nlmsg_flags = NLM_F_REQUEST;
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nlh->nlmsg_seq = 0;
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nlh->nlmsg_pid = 0;
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err = NLMSG_DATA(nlh);
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err->error = -13;
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err->msg.nlmsg_len = NLMSG_HDRLEN;
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err->msg.nlmsg_type = NLMSG_NOOP;
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err->msg.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST;
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err->msg.nlmsg_seq = 42;
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err->msg.nlmsg_pid = 1234;
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rc = sendto(fd, nlh, nlh->nlmsg_len, MSG_DONTWAIT, NULL, 0);
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printf("sendto(%d, {{len=%u, type=NLMSG_ERROR, flags=NLM_F_REQUEST"
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", seq=0, pid=0}, {error=-EACCES"
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", msg={{len=%u, type=NLMSG_NOOP, flags=NLM_F_REQUEST|0x%x"
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", seq=%u, pid=%u}}}}, %u, MSG_DONTWAIT, NULL, 0) = %s\n",
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fd, nlh->nlmsg_len, err->msg.nlmsg_len, NLM_F_DUMP,
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err->msg.nlmsg_seq, err->msg.nlmsg_pid,
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nlh->nlmsg_len, sprintrc(rc));
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/* error message with room for the error code, a header, and some data */
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nlh = nlh0 - sizeof(*err) - 4;
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nlh->nlmsg_len = NLMSG_HDRLEN + sizeof(*err) + 4;
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nlh->nlmsg_type = NLMSG_ERROR;
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nlh->nlmsg_flags = NLM_F_REQUEST;
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nlh->nlmsg_seq = 0;
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nlh->nlmsg_pid = 0;
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err = NLMSG_DATA(nlh);
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err->error = -13;
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err->msg.nlmsg_len = NLMSG_HDRLEN + 4;
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err->msg.nlmsg_type = NLMSG_NOOP;
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err->msg.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST;
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err->msg.nlmsg_seq = 421;
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err->msg.nlmsg_pid = 12345;
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memcpy(NLMSG_DATA(&err->msg), "abcd", 4);
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rc = sendto(fd, nlh, nlh->nlmsg_len, MSG_DONTWAIT, NULL, 0);
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printf("sendto(%d, {{len=%u, type=NLMSG_ERROR, flags=NLM_F_REQUEST"
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", seq=0, pid=0}, {error=-EACCES"
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", msg={{len=%u, type=NLMSG_NOOP, flags=NLM_F_REQUEST|0x%x"
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", seq=%u, pid=%u}, \"abcd\"}}}, %u, MSG_DONTWAIT, NULL, 0)"
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" = %s\n",
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fd, nlh->nlmsg_len, err->msg.nlmsg_len, NLM_F_DUMP,
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err->msg.nlmsg_seq, err->msg.nlmsg_pid,
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nlh->nlmsg_len, sprintrc(rc));
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}
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int main(void)
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{
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struct sockaddr_nl addr;
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@ -227,6 +345,7 @@ int main(void)
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free(path);
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send_query(fd);
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test_nlmsgerr(fd);
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printf("+++ exited with 0 +++\n");
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