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Message-ID:
<DM6PR12MB451623DAE30582C45BB95A3FD88BA@DM6PR12MB4516.namprd12.prod.outlook.com>
Date: Sun, 18 Jan 2026 11:30:14 +0000
From: Danielle Ratson <danieller@...dia.com>
To: Willem de Bruijn <willemdebruijn.kernel@...il.com>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC: "linux-kselftest@...r.kernel.org" <linux-kselftest@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"davem@...emloft.net" <davem@...emloft.net>, "edumazet@...gle.com"
<edumazet@...gle.com>, "kuba@...nel.org" <kuba@...nel.org>,
"pabeni@...hat.com" <pabeni@...hat.com>, "horms@...nel.org"
<horms@...nel.org>, "shuah@...nel.org" <shuah@...nel.org>, mlxsw
<mlxsw@...dia.com>
Subject: RE: [PATCH net-next] selftests: net: Add kernel selftest for RFC 4884
> -----Original Message-----
> From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
> Sent: Thursday, 15 January 2026 16:51
> To: Danielle Ratson <danieller@...dia.com>; netdev@...r.kernel.org
> Cc: linux-kselftest@...r.kernel.org; linux-kernel@...r.kernel.org;
> davem@...emloft.net; edumazet@...gle.com; kuba@...nel.org;
> pabeni@...hat.com; horms@...nel.org; shuah@...nel.org; mlxsw
> <mlxsw@...dia.com>; Danielle Ratson <danieller@...dia.com>
> Subject: Re: [PATCH net-next] selftests: net: Add kernel selftest for RFC 4884
>
> Danielle Ratson wrote:
> > RFC 4884 extended certain ICMP messages with a length attribute that
> > encodes the length of the "original datagram" field. This is needed so
> > that new information could be appended to these messages without
> > applications thinking that it is part of the "original datagram" field.
> >
> > In version 5.9, the kernel was extended with two new socket options
> > (SOL_IP/IP_RECVERR_4884 and SOL_IPV6/IPV6_RECVERR_RFC4884) that
> allow
> > user space to retrieve this length which is basically the offset to
> > the ICMP Extension Structure at the end of the ICMP message. This is
> > required by user space applications that need to parse the information
> > contained in the ICMP Extension Structure. For example, the RFC 5837
> > extension for tracepath.
> >
> > Add a selftest that verifies correct handling of the RFC 4884 length
> > field for both IPv4 and IPv6, with and without extension structures,
> > and validates that malformed extensions are correctly reported as invalid.
> >
> > For each address family, the test creates:
> > - a raw socket used to send locally crafted ICMP error packets to the
> > loopback address, and
> > - a datagram socket used to receive the encapsulated original datagram
> > and associated error metadata from the kernel error queue.
> >
> > ICMP packets are constructed entirely in user space rather than
> > relying on kernel-generated errors. This allows the test to exercise
> > invalid scenarios (such as corrupted checksums and incorrect length
> > fields) and verify that the SO_EE_RFC4884_FLAG_INVALID flag is set as
> expected.
> >
> > Output Example:
> >
> > $ ./icmp_rfc4884
> > Starting 18 tests from 18 test cases.
> > RUN rfc4884.ipv4_ext_small_payload.rfc4884 ...
> > OK rfc4884.ipv4_ext_small_payload.rfc4884
> > ok 1 rfc4884.ipv4_ext_small_payload.rfc4884
> > RUN rfc4884.ipv4_ext.rfc4884 ...
> > OK rfc4884.ipv4_ext.rfc4884 ok 2 rfc4884.ipv4_ext.rfc4884
> > RUN rfc4884.ipv4_ext_large_payload.rfc4884 ...
> > OK rfc4884.ipv4_ext_large_payload.rfc4884
> > ok 3 rfc4884.ipv4_ext_large_payload.rfc4884
> > RUN rfc4884.ipv4_no_ext_small_payload.rfc4884 ...
> > OK rfc4884.ipv4_no_ext_small_payload.rfc4884
> > ok 4 rfc4884.ipv4_no_ext_small_payload.rfc4884
> > RUN rfc4884.ipv4_no_ext_min_payload.rfc4884 ...
> > OK rfc4884.ipv4_no_ext_min_payload.rfc4884
> > ok 5 rfc4884.ipv4_no_ext_min_payload.rfc4884
> > RUN rfc4884.ipv4_no_ext_large_payload.rfc4884 ...
> > OK rfc4884.ipv4_no_ext_large_payload.rfc4884
> > ok 6 rfc4884.ipv4_no_ext_large_payload.rfc4884
> > RUN rfc4884.ipv4_invalid_ext_checksum.rfc4884 ...
> > OK rfc4884.ipv4_invalid_ext_checksum.rfc4884
> > ok 7 rfc4884.ipv4_invalid_ext_checksum.rfc4884
> > RUN rfc4884.ipv4_invalid_ext_length_small.rfc4884 ...
> > OK rfc4884.ipv4_invalid_ext_length_small.rfc4884
> > ok 8 rfc4884.ipv4_invalid_ext_length_small.rfc4884
> > RUN rfc4884.ipv4_invalid_ext_length_large.rfc4884 ...
> > OK rfc4884.ipv4_invalid_ext_length_large.rfc4884
> > ok 9 rfc4884.ipv4_invalid_ext_length_large.rfc4884
> > RUN rfc4884.ipv6_ext_small_payload.rfc4884 ...
> > OK rfc4884.ipv6_ext_small_payload.rfc4884
> > ok 10 rfc4884.ipv6_ext_small_payload.rfc4884
> > RUN rfc4884.ipv6_ext.rfc4884 ...
> > OK rfc4884.ipv6_ext.rfc4884 ok 11
> > rfc4884.ipv6_ext.rfc4884
> > RUN rfc4884.ipv6_ext_large_payload.rfc4884 ...
> > OK rfc4884.ipv6_ext_large_payload.rfc4884
> > ok 12 rfc4884.ipv6_ext_large_payload.rfc4884
> > RUN rfc4884.ipv6_no_ext_small_payload.rfc4884 ...
> > OK rfc4884.ipv6_no_ext_small_payload.rfc4884
> > ok 13 rfc4884.ipv6_no_ext_small_payload.rfc4884
> > RUN rfc4884.ipv6_no_ext_min_payload.rfc4884 ...
> > OK rfc4884.ipv6_no_ext_min_payload.rfc4884
> > ok 14 rfc4884.ipv6_no_ext_min_payload.rfc4884
> > RUN rfc4884.ipv6_no_ext_large_payload.rfc4884 ...
> > OK rfc4884.ipv6_no_ext_large_payload.rfc4884
> > ok 15 rfc4884.ipv6_no_ext_large_payload.rfc4884
> > RUN rfc4884.ipv6_invalid_ext_checksum.rfc4884 ...
> > OK rfc4884.ipv6_invalid_ext_checksum.rfc4884
> > ok 16 rfc4884.ipv6_invalid_ext_checksum.rfc4884
> > RUN rfc4884.ipv6_invalid_ext_length_small.rfc4884 ...
> > OK rfc4884.ipv6_invalid_ext_length_small.rfc4884
> > ok 17 rfc4884.ipv6_invalid_ext_length_small.rfc4884
> > RUN rfc4884.ipv6_invalid_ext_length_large.rfc4884 ...
> > OK rfc4884.ipv6_invalid_ext_length_large.rfc4884
> > ok 18 rfc4884.ipv6_invalid_ext_length_large.rfc4884
> > PASSED: 18 / 18 tests passed.
> > Totals: pass:18 fail:0 xfail:0 xpass:0 skip:0 error:0
> >
> > Signed-off-by: Danielle Ratson <danieller@...dia.com>
> > Reviewed-by: Ido Schimmel <idosch@...dia.com>
> > ---
> > tools/testing/selftests/net/.gitignore | 1 +
> > tools/testing/selftests/net/Makefile | 1 +
> > tools/testing/selftests/net/icmp_rfc4884.c | 658
> > +++++++++++++++++++++
> > 3 files changed, 660 insertions(+)
> > create mode 100644 tools/testing/selftests/net/icmp_rfc4884.c
> >
> > diff --git a/tools/testing/selftests/net/.gitignore
> > b/tools/testing/selftests/net/.gitignore
> > index 6930fe926c58..97ad4d551d44 100644
> > --- a/tools/testing/selftests/net/.gitignore
> > +++ b/tools/testing/selftests/net/.gitignore
> > @@ -7,6 +7,7 @@ cmsg_sender
> > epoll_busy_poll
> > fin_ack_lat
> > hwtstamp_config
> > +icmp_rfc4884
> > io_uring_zerocopy_tx
> > ioam6_parser
> > ip_defrag
> > diff --git a/tools/testing/selftests/net/Makefile
> > b/tools/testing/selftests/net/Makefile
> > index b66ba04f19d9..fe7937dc5f45 100644
> > --- a/tools/testing/selftests/net/Makefile
> > +++ b/tools/testing/selftests/net/Makefile
> > @@ -166,6 +166,7 @@ TEST_GEN_PROGS := \
> > bind_timewait \
> > bind_wildcard \
> > epoll_busy_poll \
> > + icmp_rfc4884 \
> > ipv6_fragmentation \
> > proc_net_pktgen \
> > reuseaddr_conflict \
> > diff --git a/tools/testing/selftests/net/icmp_rfc4884.c
> > b/tools/testing/selftests/net/icmp_rfc4884.c
> > new file mode 100644
> > index 000000000000..043965289116
> > --- /dev/null
> > +++ b/tools/testing/selftests/net/icmp_rfc4884.c
> > @@ -0,0 +1,658 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +
> > +#include <linux/icmp.h>
> > +#include <linux/icmpv6.h>
> > +#include <linux/in6.h>
> > +#include <linux/ip.h>
> > +#include <linux/ipv6.h>
> > +#include <linux/errqueue.h>
>
> no need to respin but tiny: alphabetical ordering
Ok.
>
> > +#include <sched.h>
> > +#include <stdbool.h>
> > +#include <stdint.h>
> > +#include <stdio.h>
> > +#include <stdlib.h>
> > +#include <sys/ioctl.h>
> > +#include <sys/socket.h>
> > +#include <netinet/in.h>
> > +#include <netinet/udp.h>
> > +
> > +#include "../kselftest_harness.h"
> > +
> > +#define SRC_PORT 44444
> > +#define DST_PORT 55555
> > +#define MIN_ORIG_DGRAM_LEN 128
> > +#define MIN_PAYLOAD_LEN_V4 \
> > + (MIN_ORIG_DGRAM_LEN - sizeof(struct iphdr) - sizeof(struct
> udphdr))
> > +#define MIN_PAYLOAD_LEN_V6 \
> > + (MIN_ORIG_DGRAM_LEN - sizeof(struct ipv6hdr) - sizeof(struct
> > +udphdr)) #define ORIG_PAYLOAD_BYTE 0xAA
>
> only if respinning: prefer typed (const) variables over macros
Ok
>
> > +
> > +struct sockaddr_inet {
> > + union {
> > + struct sockaddr_in6 v6;
> > + struct sockaddr_in v4;
> > + struct sockaddr sa;
> > + };
> > + socklen_t len;
> > +};
> > +
> > +struct ip_case_info {
> > + int domain;
> > + int level;
> > + int opt1;
> > + int opt2;
> > + int proto;
> > + int (*build_func)(uint8_t *buf, ssize_t buflen, bool with_ext,
> > + int payload_len, bool bad_csum, bool bad_len,
> > + bool smaller_len);
> > + int min_payload;
> > +};
> > +
> > +static int bringup_loopback(void)
> > +{
> > + struct ifreq ifr = {
> > + .ifr_name = "lo"
> > + };
> > + int fd;
> > +
> > + fd = socket(AF_INET, SOCK_DGRAM, 0);
> > + if (fd < 0)
> > + return -1;
> > +
> > + if (ioctl(fd, SIOCGIFFLAGS, &ifr) < 0)
> > + goto err;
> > +
> > + ifr.ifr_flags = ifr.ifr_flags | IFF_UP;
> > +
> > + if (ioctl(fd, SIOCSIFFLAGS, &ifr) < 0)
> > + goto err;
> > +
> > + close(fd);
> > + return 0;
> > +
> > +err:
> > + close(fd);
> > + return -1;
> > +}
> > +
> > +static uint16_t csum(const void *buf, size_t len) {
> > + const uint8_t *data = buf;
> > + uint32_t sum = 0;
> > +
> > + while (len > 1) {
> > + sum += (data[0] << 8) | data[1];
> > + data += 2;
> > + len -= 2;
> > + }
> > +
> > + if (len == 1)
> > + sum += data[0] << 8;
> > +
> > + while (sum >> 16)
> > + sum = (sum & 0xFFFF) + (sum >> 16);
> > +
> > + return ~sum & 0xFFFF;
> > +}
> > +
> > +static void set_addr(struct sockaddr_inet *addr, int domain, int
> > +port) {
> > + memset(addr, 0, sizeof(*addr));
> > +
> > + switch (domain) {
> > + case AF_INET:
> > + addr->v4.sin_family = AF_INET;
> > + addr->v4.sin_port = htons(port);
> > + addr->v4.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
> > + addr->len = sizeof(addr->v4);
> > + break;
> > + case AF_INET6:
> > + addr->v6.sin6_family = AF_INET6;
> > + addr->v6.sin6_port = htons(port);
> > + addr->v6.sin6_addr = in6addr_loopback;
> > + addr->len = sizeof(addr->v6);
> > + break;
> > + }
> > +}
> > +
> > +static int bind_to_loopback(int fd, const struct ip_case_info *info)
> > +{
> > + struct sockaddr_inet addr;
> > + int opt = 1;
> > +
> > + set_addr(&addr, info->domain, SRC_PORT);
> > +
> > + if (setsockopt(fd, info->level, info->opt1, &opt, sizeof(opt)) < 0)
> > + return -1;
> > +
> > + if (setsockopt(fd, info->level, info->opt2, &opt, sizeof(opt)) < 0)
> > + return -1;
> > +
>
> no need to respin just for this but nit: this does more than the function name
> covers. I was looking for where IPV6_RECVERR was set.
Will do.
>
> > + return bind(fd, &addr.sa, addr.len); }
> > +
> > +static int build_rfc4884_ext(uint8_t *buf, size_t buflen, bool bad_csum,
> > + bool bad_len, bool smaller_len) {
> > + struct icmp_extobj_hdr *objh;
> > + struct icmp_ext_hdr *exthdr;
> > + size_t obj_len, ext_len;
> > + uint16_t sum;
> > +
> > + /* Use an object payload of 4 bytes */
> > + obj_len = sizeof(*objh) + sizeof(uint32_t);
> > + ext_len = sizeof(*exthdr) + obj_len;
> > +
> > + if (ext_len > buflen)
> > + return -EINVAL;
> > +
> > + exthdr = (struct icmp_ext_hdr *)buf;
> > + objh = (struct icmp_extobj_hdr *)(buf + sizeof(*exthdr));
> > +
> > + exthdr->version = 2;
> > + /* When encoding a bad object length, either encode a length too
> small
> > + * to fit the object header or too big to fit in the packet.
> > + */
> > + if (bad_len)
> > + obj_len = smaller_len ? sizeof(*objh) - 1 : obj_len * 2;
> > + objh->length = htons(obj_len);
> > +
> > + sum = csum(buf, ext_len);
> > + exthdr->checksum = htons(bad_csum ? sum - 1 : sum);
> > +
> > + return ext_len;
> > +}
> > +
> > +static int build_orig_dgram_v4(uint8_t *buf, ssize_t buflen, int
> > +payload_len) {
> > + struct udphdr *udph;
> > + struct iphdr *iph;
> > + size_t len = 0;
> > +
> > + len = sizeof(*iph) + sizeof(*udph) + payload_len;
> > + if (len > buflen)
> > + return -EINVAL;
> > +
> > + iph = (struct iphdr *)buf;
> > + udph = (struct udphdr *)(buf + sizeof(*iph));
> > +
> > + iph->version = 4;
> > + iph->ihl = 5;
> > + iph->protocol = IPPROTO_UDP;
> > + iph->saddr = htonl(INADDR_LOOPBACK);
> > + iph->daddr = htonl(INADDR_LOOPBACK);
> > + iph->tot_len = htons(len);
> > + iph->check = htons(csum(iph, sizeof(*iph)));
> > +
> > + udph->source = htons(SRC_PORT);
> > + udph->dest = htons(DST_PORT);
> > + udph->len = htons(sizeof(*udph) + payload_len);
> > +
> > + memset(buf + sizeof(*iph) + sizeof(*udph), ORIG_PAYLOAD_BYTE,
> > + payload_len);
> > +
> > + return len;
> > +}
> > +
> > +static int build_orig_dgram_v6(uint8_t *buf, ssize_t buflen, int
> > +payload_len) {
> > + struct udphdr *udph;
> > + struct ipv6hdr *iph;
> > + size_t len = 0;
> > +
> > + len = sizeof(*iph) + sizeof(*udph) + payload_len;
> > + if (len > buflen)
> > + return -EINVAL;
> > +
> > + iph = (struct ipv6hdr *)buf;
> > + udph = (struct udphdr *)(buf + sizeof(*iph));
> > +
> > + iph->version = 6;
> > + iph->payload_len = htons(sizeof(*udph) + payload_len);
> > + iph->nexthdr = IPPROTO_UDP;
> > + iph->saddr = in6addr_loopback;
> > + iph->daddr = in6addr_loopback;
> > +
> > + udph->source = htons(SRC_PORT);
> > + udph->dest = htons(DST_PORT);
> > + udph->len = htons(sizeof(*udph) + payload_len);
> > +
> > + memset(buf + sizeof(*iph) + sizeof(*udph), ORIG_PAYLOAD_BYTE,
> > + payload_len);
> > +
> > + return len;
> > +}
> > +
> > +static int build_icmpv4_pkt(uint8_t *buf, ssize_t buflen, bool with_ext,
> > + int payload_len, bool bad_csum, bool bad_len,
> > + bool smaller_len)
> > +{
> > + struct icmphdr *icmph;
> > + int len, ret;
> > +
> > + len = sizeof(*icmph);
> > + memset(buf, 0, buflen);
> > +
> > + icmph = (struct icmphdr *)buf;
> > + icmph->type = ICMP_DEST_UNREACH;
> > + icmph->code = ICMP_PORT_UNREACH;
> > + icmph->checksum = 0;
> > +
> > + ret = build_orig_dgram_v4(buf + len, buflen - len, payload_len);
> > + if (ret < 0)
> > + return ret;
> > +
> > + len += ret;
> > +
> > + icmph->un.reserved[1] = (len - sizeof(*icmph)) / sizeof(uint32_t);
> > +
> > + if (with_ext) {
> > + ret = build_rfc4884_ext(buf + len, buflen - len,
> > + bad_csum, bad_len, smaller_len);
> > + if (ret < 0)
> > + return ret;
> > +
> > + len += ret;
> > + }
> > +
> > + icmph->checksum = htons(csum(icmph, len));
> > + return len;
> > +}
> > +
> > +static int build_icmpv6_pkt(uint8_t *buf, ssize_t buflen, bool with_ext,
> > + int payload_len, bool bad_csum, bool bad_len,
> > + bool smaller_len)
> > +{
> > + struct icmp6hdr *icmph;
> > + int len, ret;
> > +
> > + len = sizeof(*icmph);
> > + memset(buf, 0, buflen);
> > +
> > + icmph = (struct icmp6hdr *)buf;
> > + icmph->icmp6_type = ICMPV6_DEST_UNREACH;
> > + icmph->icmp6_code = ICMPV6_PORT_UNREACH;
> > + icmph->icmp6_cksum = 0;
> > +
> > + ret = build_orig_dgram_v6(buf + len, buflen - len, payload_len);
> > + if (ret < 0)
> > + return ret;
> > +
> > + len += ret;
> > +
> > + icmph->icmp6_datagram_len = (len - sizeof(*icmph)) /
> > +sizeof(uint64_t);
> > +
> > + if (with_ext) {
> > + ret = build_rfc4884_ext(buf + len, buflen - len,
> > + bad_csum, bad_len, smaller_len);
> > + if (ret < 0)
> > + return ret;
> > +
> > + len += ret;
> > + }
> > +
> > + icmph->icmp6_cksum = htons(csum(icmph, len));
> > + return len;
> > +}
> > +
> > +FIXTURE(rfc4884) {};
> > +
> > +FIXTURE_SETUP(rfc4884)
> > +{
> > + int ret;
> > +
> > + ret = unshare(CLONE_NEWNET);
> > + ASSERT_EQ(ret, 0) {
> > + TH_LOG("unshare(CLONE_NEWNET) failed: %s",
> strerror(errno));
> > + }
> > +
> > + ret = bringup_loopback();
> > + ASSERT_EQ(ret, 0) TH_LOG("Failed to bring up loopback interface"); }
> > +
> > +FIXTURE_TEARDOWN(rfc4884)
> > +{
> > +}
> > +
> > +const struct ip_case_info ipv4_info = {
> > + .domain = AF_INET,
> > + .level = SOL_IP,
> > + .opt1 = IP_RECVERR,
> > + .opt2 = IP_RECVERR_RFC4884,
> > + .proto = IPPROTO_ICMP,
> > + .build_func = build_icmpv4_pkt,
> > + .min_payload = MIN_PAYLOAD_LEN_V4,
> > +};
> > +
> > +const struct ip_case_info ipv6_info = {
> > + .domain = AF_INET6,
> > + .level = SOL_IPV6,
> > + .opt1 = IPV6_RECVERR,
> > + .opt2 = IPV6_RECVERR_RFC4884,
> > + .proto = IPPROTO_ICMPV6,
> > + .build_func = build_icmpv6_pkt,
> > + .min_payload = MIN_PAYLOAD_LEN_V6,
> > +};
> > +
> > +FIXTURE_VARIANT(rfc4884) {
> > + /* IPv4/v6 related information */
> > + struct ip_case_info info;
> > + /* Whether to append an ICMP extension or not */
> > + bool with_ext;
> > + /* UDP payload length */
> > + int payload_len;
> > + /* Whether to generate a bad checksum in the ICMP extension
> structure */
> > + bool bad_csum;
> > + /* Whether to generate a bad length in the ICMP object header */
> > + bool bad_len;
> > + /* Whether it is too small to fit the object header or too big to fit
> > + * in the packet
> > + */
> > + bool smaller_len;
> > +};
> > +
> > +/* Tests that a valid ICMPv4 error message with extension and the
> > +original
> > + * datagram is smaller than 128 bytes, generates an error with zero
> > +offset,
> > + * and does not raise the SO_EE_RFC4884_FLAG_INVALID flag.
> > + */
> > +FIXTURE_VARIANT_ADD(rfc4884, ipv4_ext_small_payload) {
> > + .info = ipv4_info,
> > + .with_ext = true,
> > + .payload_len = 64,
> > + .bad_csum = false,
> > + .bad_len = false,
> > +};
> > +
> > +/* Tests that a valid ICMPv4 error message with extension and 128
> > +bytes original
> > + * datagram, generates an error with the expected offset, and does
> > +not raise the
> > + * SO_EE_RFC4884_FLAG_INVALID flag.
> > + */
> > +FIXTURE_VARIANT_ADD(rfc4884, ipv4_ext) {
> > + .info = ipv4_info,
> > + .with_ext = true,
> > + .payload_len = MIN_PAYLOAD_LEN_V4,
> > + .bad_csum = false,
> > + .bad_len = false,
> > +};
> > +
> > +/* Tests that a valid ICMPv4 error message with extension and the
> > +original
> > + * datagram is larger than 128 bytes, generates an error with the
> > +expected
> > + * offset, and does not raise the SO_EE_RFC4884_FLAG_INVALID flag.
> > + */
> > +FIXTURE_VARIANT_ADD(rfc4884, ipv4_ext_large_payload) {
> > + .info = ipv4_info,
> > + .with_ext = true,
> > + .payload_len = 256,
> > + .bad_csum = false,
> > + .bad_len = false,
> > +};
> > +
> > +/* Tests that a valid ICMPv4 error message without extension and the
> > +original
> > + * datagram is smaller than 128 bytes, generates an error with zero
> > +offset,
> > + * and does not raise the SO_EE_RFC4884_FLAG_INVALID flag.
> > + */
> > +FIXTURE_VARIANT_ADD(rfc4884, ipv4_no_ext_small_payload) {
> > + .info = ipv4_info,
> > + .with_ext = false,
> > + .payload_len = 64,
> > + .bad_csum = false,
> > + .bad_len = false,
> > +};
> > +
> > +/* Tests that a valid ICMPv4 error message without extension and 128
> > +bytes
> > + * original datagram, generates an error with zero offset, and does
> > +not raise
> > + * the SO_EE_RFC4884_FLAG_INVALID flag.
> > + */
> > +FIXTURE_VARIANT_ADD(rfc4884, ipv4_no_ext_min_payload) {
> > + .info = ipv4_info,
> > + .with_ext = false,
> > + .payload_len = MIN_PAYLOAD_LEN_V4,
> > + .bad_csum = false,
> > + .bad_len = false,
> > +};
> > +
> > +/* Tests that a valid ICMPv4 error message without extension and the
> > +original
> > + * datagram is larger than 128 bytes, generates an error with zero
> > +offset,
> > + * and does not raise the SO_EE_RFC4884_FLAG_INVALID flag.
> > + */
> > +FIXTURE_VARIANT_ADD(rfc4884, ipv4_no_ext_large_payload) {
> > + .info = ipv4_info,
> > + .with_ext = false,
> > + .payload_len = 256,
> > + .bad_csum = false,
> > + .bad_len = false,
> > +};
> > +
> > +/* Tests that an ICMPv4 error message with extension and an invalid
> > +checksum,
> > + * generates an error with the expected offset, and raises the
> > + * SO_EE_RFC4884_FLAG_INVALID flag.
> > + */
> > +FIXTURE_VARIANT_ADD(rfc4884, ipv4_invalid_ext_checksum) {
> > + .info = ipv4_info,
> > + .with_ext = true,
> > + .payload_len = MIN_PAYLOAD_LEN_V4,
> > + .bad_csum = true,
> > + .bad_len = false,
> > +};
> > +
> > +/* Tests that an ICMPv4 error message with extension and an object
> > +length
> > + * smaller than the object header, generates an error with the
> > +expected offset,
> > + * and raises the SO_EE_RFC4884_FLAG_INVALID flag.
> > + */
> > +FIXTURE_VARIANT_ADD(rfc4884, ipv4_invalid_ext_length_small) {
> > + .info = ipv4_info,
> > + .with_ext = true,
> > + .payload_len = MIN_PAYLOAD_LEN_V4,
> > + .bad_csum = false,
> > + .bad_len = true,
> > + .smaller_len = true,
> > +};
> > +
> > +/* Tests that an ICMPv4 error message with extension and an object
> > +length that
> > + * is too big to fit in the packet, generates an error with the
> > +expected offset,
> > + * and raises the SO_EE_RFC4884_FLAG_INVALID flag.
> > + */
> > +FIXTURE_VARIANT_ADD(rfc4884, ipv4_invalid_ext_length_large) {
> > + .info = ipv4_info,
> > + .with_ext = true,
> > + .payload_len = MIN_PAYLOAD_LEN_V4,
> > + .bad_csum = false,
> > + .bad_len = true,
> > + .smaller_len = false,
> > +};
> > +
> > +/* Tests that a valid ICMPv6 error message with extension and the
> > +original
> > + * datagram is smaller than 128 bytes, generates an error with zero
> > +offset,
> > + * and does not raise the SO_EE_RFC4884_FLAG_INVALID flag.
> > + */
> > +FIXTURE_VARIANT_ADD(rfc4884, ipv6_ext_small_payload) {
> > + .info = ipv6_info,
> > + .with_ext = true,
> > + .payload_len = 64,
> > + .bad_csum = false,
> > + .bad_len = false,
> > +};
> > +
> > +/* Tests that a valid ICMPv6 error message with extension and 128
> > +bytes original
> > + * datagram, generates an error with the expected offset, and does
> > +not raise the
> > + * SO_EE_RFC4884_FLAG_INVALID flag.
> > + */
> > +FIXTURE_VARIANT_ADD(rfc4884, ipv6_ext) {
> > + .info = ipv6_info,
> > + .with_ext = true,
> > + .payload_len = MIN_PAYLOAD_LEN_V6,
> > + .bad_csum = false,
> > + .bad_len = false,
> > +};
> > +
> > +/* Tests that a valid ICMPv6 error message with extension and the
> > +original
> > + * datagram is larger than 128 bytes, generates an error with the
> > +expected
> > + * offset, and does not raise the SO_EE_RFC4884_FLAG_INVALID flag.
> > + */
> > +FIXTURE_VARIANT_ADD(rfc4884, ipv6_ext_large_payload) {
> > + .info = ipv6_info,
> > + .with_ext = true,
> > + .payload_len = 256,
> > + .bad_csum = false,
> > + .bad_len = false,
> > +};
> > +/* Tests that a valid ICMPv6 error message without extension and the
> > +original
> > + * datagram is smaller than 128 bytes, generates an error with zero
> > +offset,
> > + * and does not raise the SO_EE_RFC4884_FLAG_INVALID flag.
> > + */
> > +FIXTURE_VARIANT_ADD(rfc4884, ipv6_no_ext_small_payload) {
> > + .info = ipv6_info,
> > + .with_ext = false,
> > + .payload_len = 64,
> > + .bad_csum = false,
> > + .bad_len = false,
> > +};
> > +
> > +/* Tests that a valid ICMPv6 error message without extension and 128
> > +bytes
> > + * original datagram, generates an error with zero offset, and does
> > +not
> > + * raise the SO_EE_RFC4884_FLAG_INVALID flag.
> > + */
> > +FIXTURE_VARIANT_ADD(rfc4884, ipv6_no_ext_min_payload) {
> > + .info = ipv6_info,
> > + .with_ext = false,
> > + .payload_len = MIN_PAYLOAD_LEN_V6,
> > + .bad_csum = false,
> > + .bad_len = false,
> > +};
> > +
> > +/* Tests that a valid ICMPv6 error message without extension and the
> > +original
> > + * datagram is larger than 128 bytes, generates an error with zero
> > +offset,
> > + * and does not raise the SO_EE_RFC4884_FLAG_INVALID flag.
> > + */
> > +FIXTURE_VARIANT_ADD(rfc4884, ipv6_no_ext_large_payload) {
> > + .info = ipv6_info,
> > + .with_ext = false,
> > + .payload_len = 256,
> > + .bad_csum = false,
> > + .bad_len = false,
> > +};
> > +
> > +/* Tests that an ICMPv6 error message with extension and an invalid
> > +checksum,
> > + * generates an error with the expected offset, and raises the
> > + * SO_EE_RFC4884_FLAG_INVALID flag.
> > + */
> > +FIXTURE_VARIANT_ADD(rfc4884, ipv6_invalid_ext_checksum) {
> > + .info = ipv6_info,
> > + .with_ext = true,
> > + .payload_len = MIN_PAYLOAD_LEN_V6,
> > + .bad_csum = true,
> > + .bad_len = false,
> > +};
> > +
> > +/* Tests that an ICMPv6 error message with extension and an object
> > +length
> > + * smaller than the object header, generates an error with the
> > +expected offset,
> > + * and raises the SO_EE_RFC4884_FLAG_INVALID flag.
> > + */
> > +FIXTURE_VARIANT_ADD(rfc4884, ipv6_invalid_ext_length_small) {
> > + .info = ipv6_info,
> > + .with_ext = true,
> > + .payload_len = MIN_PAYLOAD_LEN_V6,
> > + .bad_csum = false,
> > + .bad_len = true,
> > + .smaller_len = true,
> > +};
> > +
> > +/* Tests that an ICMPv6 error message with extension and an object
> > +length that
> > + * is too big to fit in the packet, generates an error with the
> > +expected offset,
> > + * and raises the SO_EE_RFC4884_FLAG_INVALID flag.
> > + */
> > +FIXTURE_VARIANT_ADD(rfc4884, ipv6_invalid_ext_length_large) {
> > + .info = ipv6_info,
> > + .with_ext = true,
> > + .payload_len = MIN_PAYLOAD_LEN_V6,
> > + .bad_csum = false,
> > + .bad_len = true,
> > + .smaller_len = false,
> > +};
> > +
> > +static void
> > +check_rfc4884_offset(struct __test_metadata *_metadata, int sock,
> > + const FIXTURE_VARIANT(rfc4884) *v) {
> > + char rxbuf[1024];
> > + char ctrl[1024];
> > + struct iovec iov = {
> > + .iov_base = rxbuf,
> > + .iov_len = sizeof(rxbuf)
> > + };
> > + struct msghdr msg = {
> > + .msg_iov = &iov,
> > + .msg_iovlen = 1,
> > + .msg_control = ctrl,
> > + .msg_controllen = sizeof(ctrl),
> > + };
> > + struct cmsghdr *cmsg;
> > + int recv;
> > +
> > + recv = recvmsg(sock, &msg, MSG_ERRQUEUE);
>
> Reading from the error queue does not block.
>
> Is it assured that the ICMP packet is queued on return from sendmsg?
> Or does this need a poll to be on the safe side wrt flakes.
Will add a poll, thanks.
>
> > + ASSERT_GE(recv, 0) TH_LOG("recvmsg(MSG_ERRQUEUE) failed");
> > +
> > + for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg =
> CMSG_NXTHDR(&msg, cmsg)) {
> > + bool is_invalid, expected_invalid;
> > + struct sock_extended_err *ee;
> > + int expected_off;
> > + uint16_t off;
> > +
> > + if (cmsg->cmsg_level != v->info.level &&
> > + cmsg->cmsg_type != v->info.opt1)
> > + continue;
>
> Do we expect any other cmsg? Else just fail if encountering them, to make the
> test more strict?
We do not expect any other control messages in this case. However, I prefer not to fail the test on unrelated ancillary data, as this would make the test more brittle.
Ignoring unknown cmsg entries makes the test more robust against unrelated kernel behavior changes, while still validating the information we care about.
>
> > +
> > + ee = (struct sock_extended_err *)CMSG_DATA(cmsg);
> > + off = ee->ee_rfc4884.len;
> > + is_invalid = ee->ee_rfc4884.flags &
> SO_EE_RFC4884_FLAG_INVALID;
> > +
> > + expected_invalid = v->bad_csum || v->bad_len;
> > + ASSERT_EQ(is_invalid, expected_invalid) {
> > + TH_LOG("Expected invalidity flag to be %d, but got
> %d",
> > + expected_invalid, is_invalid);
> > + }
> > +
> > + expected_off =
> > + (v->with_ext && v->payload_len >= v-
> >info.min_payload) ?
> > + v->payload_len : 0;
> > + ASSERT_EQ(off, expected_off) {
> > + TH_LOG("Expected RFC4884 offset %u, got %u",
> > + expected_off, off);
> > + }
> > + break;
> > + }
> > +}
> > +
> > +TEST_F(rfc4884, rfc4884)
> > +{
> > + const typeof(variant) v = variant;
> > + struct sockaddr_inet addr;
> > + uint8_t pkt[1024];
> > + int dgram, raw;
> > + int len, sent;
> > + int err;
> > +
> > + dgram = socket(v->info.domain, SOCK_DGRAM, 0);
> > + ASSERT_GE(dgram, 0) TH_LOG("Opening datagram socket failed");
> > +
> > + err = bind_to_loopback(dgram, &v->info);
> > + ASSERT_EQ(err, 0) TH_LOG("Bind failed");
> > +
> > + raw = socket(v->info.domain, SOCK_RAW, v->info.proto);
> > + ASSERT_GE(raw, 0) TH_LOG("Opening raw socket failed");
> > +
> > + len = v->info.build_func(pkt, sizeof(pkt), v->with_ext, v->payload_len,
> > + v->bad_csum, v->bad_len, v->smaller_len);
> > + ASSERT_GT(len, 0) TH_LOG("Building packet failed");
> > +
> > + set_addr(&addr, v->info.domain, 0);
> > + sent = sendto(raw, pkt, len, 0, &addr.sa, addr.len);
> > + ASSERT_EQ(len, sent) TH_LOG("Sending packet failed");
> > +
> > + check_rfc4884_offset(_metadata, dgram, v);
> > +
> > + close(dgram);
> > + close(raw);
> > +}
> > +
> > +TEST_HARNESS_MAIN
> > --
> > 2.51.0
> >
>
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