From: Peter Oskolkov posk@google.com
[ Upstream commit 3271a4821882a64214acc1bd7b173900ec70c9bf ]
Commit ade446403bfb ("net: ipv4: do not handle duplicate fragments as overlapping") changed IPv4 defragmentation so that duplicate fragments, as well as _some_ fragments completely covered by previously delivered fragments, do not lead to the whole frag queue being discarded. This makes the existing ip_defrag selftest flaky.
This patch * makes sure that negative IPv4 defrag tests generate truly overlapping fragments that trigger defrag queue drops; * tests that duplicate IPv4 fragments do not trigger defrag queue drops; * makes a couple of minor tweaks to the test aimed at increasing its code coverage and reduce flakiness.
Signed-off-by: Peter Oskolkov posk@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- tools/testing/selftests/net/ip_defrag.c | 96 +++++++++++++++++++++--- tools/testing/selftests/net/ip_defrag.sh | 9 ++- 2 files changed, 95 insertions(+), 10 deletions(-)
diff --git a/tools/testing/selftests/net/ip_defrag.c b/tools/testing/selftests/net/ip_defrag.c index 61ae2782388e..5d56cc0838f6 100644 --- a/tools/testing/selftests/net/ip_defrag.c +++ b/tools/testing/selftests/net/ip_defrag.c @@ -203,6 +203,7 @@ static void send_udp_frags(int fd_raw, struct sockaddr *addr, { struct ip *iphdr = (struct ip *)ip_frame; struct ip6_hdr *ip6hdr = (struct ip6_hdr *)ip_frame; + const bool ipv4 = !ipv6; int res; int offset; int frag_len; @@ -239,19 +240,53 @@ static void send_udp_frags(int fd_raw, struct sockaddr *addr, iphdr->ip_sum = 0; }
+ /* Occasionally test in-order fragments. */ + if (!cfg_overlap && (rand() % 100 < 15)) { + offset = 0; + while (offset < (UDP_HLEN + payload_len)) { + send_fragment(fd_raw, addr, alen, offset, ipv6); + offset += max_frag_len; + } + return; + } + + /* Occasionally test IPv4 "runs" (see net/ipv4/ip_fragment.c) */ + if (ipv4 && !cfg_overlap && (rand() % 100 < 20) && + (payload_len > 9 * max_frag_len)) { + offset = 6 * max_frag_len; + while (offset < (UDP_HLEN + payload_len)) { + send_fragment(fd_raw, addr, alen, offset, ipv6); + offset += max_frag_len; + } + offset = 3 * max_frag_len; + while (offset < 6 * max_frag_len) { + send_fragment(fd_raw, addr, alen, offset, ipv6); + offset += max_frag_len; + } + offset = 0; + while (offset < 3 * max_frag_len) { + send_fragment(fd_raw, addr, alen, offset, ipv6); + offset += max_frag_len; + } + return; + } + /* Odd fragments. */ offset = max_frag_len; while (offset < (UDP_HLEN + payload_len)) { send_fragment(fd_raw, addr, alen, offset, ipv6); + /* IPv4 ignores duplicates, so randomly send a duplicate. */ + if (ipv4 && (1 == rand() % 100)) + send_fragment(fd_raw, addr, alen, offset, ipv6); offset += 2 * max_frag_len; }
if (cfg_overlap) { /* Send an extra random fragment. */ - offset = rand() % (UDP_HLEN + payload_len - 1); - /* sendto() returns EINVAL if offset + frag_len is too small. */ if (ipv6) { struct ip6_frag *fraghdr = (struct ip6_frag *)(ip_frame + IP6_HLEN); + /* sendto() returns EINVAL if offset + frag_len is too small. */ + offset = rand() % (UDP_HLEN + payload_len - 1); frag_len = max_frag_len + rand() % 256; /* In IPv6 if !!(frag_len % 8), the fragment is dropped. */ frag_len &= ~0x7; @@ -259,13 +294,29 @@ static void send_udp_frags(int fd_raw, struct sockaddr *addr, ip6hdr->ip6_plen = htons(frag_len); frag_len += IP6_HLEN; } else { - frag_len = IP4_HLEN + UDP_HLEN + rand() % 256; + /* In IPv4, duplicates and some fragments completely inside + * previously sent fragments are dropped/ignored. So + * random offset and frag_len can result in a dropped + * fragment instead of a dropped queue/packet. So we + * hard-code offset and frag_len. + * + * See ade446403bfb ("net: ipv4: do not handle duplicate + * fragments as overlapping"). + */ + if (max_frag_len * 4 < payload_len || max_frag_len < 16) { + /* not enough payload to play with random offset and frag_len. */ + offset = 8; + frag_len = IP4_HLEN + UDP_HLEN + max_frag_len; + } else { + offset = rand() % (payload_len / 2); + frag_len = 2 * max_frag_len + 1 + rand() % 256; + } iphdr->ip_off = htons(offset / 8 | IP4_MF); iphdr->ip_len = htons(frag_len); } res = sendto(fd_raw, ip_frame, frag_len, 0, addr, alen); if (res < 0) - error(1, errno, "sendto overlap"); + error(1, errno, "sendto overlap: %d", frag_len); if (res != frag_len) error(1, 0, "sendto overlap: %d vs %d", (int)res, frag_len); frag_counter++; @@ -275,6 +326,9 @@ static void send_udp_frags(int fd_raw, struct sockaddr *addr, offset = 0; while (offset < (UDP_HLEN + payload_len)) { send_fragment(fd_raw, addr, alen, offset, ipv6); + /* IPv4 ignores duplicates, so randomly send a duplicate. */ + if (ipv4 && (1 == rand() % 100)) + send_fragment(fd_raw, addr, alen, offset, ipv6); offset += 2 * max_frag_len; } } @@ -282,7 +336,11 @@ static void send_udp_frags(int fd_raw, struct sockaddr *addr, static void run_test(struct sockaddr *addr, socklen_t alen, bool ipv6) { int fd_tx_raw, fd_rx_udp; - struct timeval tv = { .tv_sec = 0, .tv_usec = 10 * 1000 }; + /* Frag queue timeout is set to one second in the calling script; + * socket timeout should be just a bit longer to avoid tests interfering + * with each other. + */ + struct timeval tv = { .tv_sec = 1, .tv_usec = 10 }; int idx; int min_frag_len = ipv6 ? 1280 : 8;
@@ -308,12 +366,32 @@ static void run_test(struct sockaddr *addr, socklen_t alen, bool ipv6) payload_len += (rand() % 4096)) { if (cfg_verbose) printf("payload_len: %d\n", payload_len); - max_frag_len = min_frag_len; - do { + + if (cfg_overlap) { + /* With overlaps, one send/receive pair below takes + * at least one second (== timeout) to run, so there + * is not enough test time to run a nested loop: + * the full overlap test takes 20-30 seconds. + */ + max_frag_len = min_frag_len + + rand() % (1500 - FRAG_HLEN - min_frag_len); send_udp_frags(fd_tx_raw, addr, alen, ipv6); recv_validate_udp(fd_rx_udp); - max_frag_len += 8 * (rand() % 8); - } while (max_frag_len < (1500 - FRAG_HLEN) && max_frag_len <= payload_len); + } else { + /* Without overlaps, each packet reassembly (== one + * send/receive pair below) takes very little time to + * run, so we can easily afford more thourough testing + * with a nested loop: the full non-overlap test takes + * less than one second). + */ + max_frag_len = min_frag_len; + do { + send_udp_frags(fd_tx_raw, addr, alen, ipv6); + recv_validate_udp(fd_rx_udp); + max_frag_len += 8 * (rand() % 8); + } while (max_frag_len < (1500 - FRAG_HLEN) && + max_frag_len <= payload_len); + } }
/* Cleanup. */ diff --git a/tools/testing/selftests/net/ip_defrag.sh b/tools/testing/selftests/net/ip_defrag.sh index f34672796044..7dd79a9efb17 100755 --- a/tools/testing/selftests/net/ip_defrag.sh +++ b/tools/testing/selftests/net/ip_defrag.sh @@ -11,10 +11,17 @@ readonly NETNS="ns-$(mktemp -u XXXXXX)" setup() { ip netns add "${NETNS}" ip -netns "${NETNS}" link set lo up + ip netns exec "${NETNS}" sysctl -w net.ipv4.ipfrag_high_thresh=9000000 >/dev/null 2>&1 ip netns exec "${NETNS}" sysctl -w net.ipv4.ipfrag_low_thresh=7000000 >/dev/null 2>&1 + ip netns exec "${NETNS}" sysctl -w net.ipv4.ipfrag_time=1 >/dev/null 2>&1 + ip netns exec "${NETNS}" sysctl -w net.ipv6.ip6frag_high_thresh=9000000 >/dev/null 2>&1 ip netns exec "${NETNS}" sysctl -w net.ipv6.ip6frag_low_thresh=7000000 >/dev/null 2>&1 + ip netns exec "${NETNS}" sysctl -w net.ipv6.ip6frag_time=1 >/dev/null 2>&1 + + # DST cache can get full with a lot of frags, with GC not keeping up with the test. + ip netns exec "${NETNS}" sysctl -w net.ipv6.route.max_size=65536 >/dev/null 2>&1 }
cleanup() { @@ -27,7 +34,6 @@ setup echo "ipv4 defrag" ip netns exec "${NETNS}" ./ip_defrag -4
- echo "ipv4 defrag with overlaps" ip netns exec "${NETNS}" ./ip_defrag -4o
@@ -37,3 +43,4 @@ ip netns exec "${NETNS}" ./ip_defrag -6 echo "ipv6 defrag with overlaps" ip netns exec "${NETNS}" ./ip_defrag -6o
+echo "all tests done"