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Message-ID: <8160619F-DEDB-44F0-8AB3-EFBD07888822@fb.com>
Date: Thu, 25 Jul 2019 17:15:12 +0000
From: Song Liu <songliubraving@...com>
To: Stanislav Fomichev <sdf@...gle.com>
CC: Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
"David S. Miller" <davem@...emloft.net>,
"ast@...nel.org" <ast@...nel.org>,
"daniel@...earbox.net" <daniel@...earbox.net>,
Willem de Bruijn <willemb@...gle.com>,
Petar Penkov <ppenkov@...gle.com>
Subject: Re: [PATCH bpf-next v2 5/7] selftests/bpf: support
FLOW_DISSECTOR_F_PARSE_1ST_FRAG
> On Jul 25, 2019, at 8:33 AM, Stanislav Fomichev <sdf@...gle.com> wrote:
>
> bpf_flow.c: exit early unless FLOW_DISSECTOR_F_PARSE_1ST_FRAG is passed
> in flags. Also, set ip_proto earlier, this makes sure we have correct
> value with fragmented packets.
>
> Add selftest cases to test ipv4/ipv6 fragments and skip eth_get_headlen
> tests that don't have FLOW_DISSECTOR_F_PARSE_1ST_FRAG flag.
>
> eth_get_headlen calls flow dissector with
> FLOW_DISSECTOR_F_PARSE_1ST_FRAG flag so we can't run tests that
> have different set of input flags against it.
>
> v2:
> * sefltests -> selftests (Willem de Bruijn)
> * Reword a comment about eth_get_headlen flags (Song Liu)
>
> Acked-by: Willem de Bruijn <willemb@...gle.com>
> Cc: Song Liu <songliubraving@...com>
> Cc: Willem de Bruijn <willemb@...gle.com>
> Cc: Petar Penkov <ppenkov@...gle.com>
> Signed-off-by: Stanislav Fomichev <sdf@...gle.com>
Acked-by: Song Liu <songliubraving@...com>
> ---
> .../selftests/bpf/prog_tests/flow_dissector.c | 132 +++++++++++++++++-
> tools/testing/selftests/bpf/progs/bpf_flow.c | 28 +++-
> 2 files changed, 153 insertions(+), 7 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/flow_dissector.c b/tools/testing/selftests/bpf/prog_tests/flow_dissector.c
> index c938283ac232..f93a115db650 100644
> --- a/tools/testing/selftests/bpf/prog_tests/flow_dissector.c
> +++ b/tools/testing/selftests/bpf/prog_tests/flow_dissector.c
> @@ -5,6 +5,10 @@
> #include <linux/if_tun.h>
> #include <sys/uio.h>
>
> +#ifndef IP_MF
> +#define IP_MF 0x2000
> +#endif
> +
> #define CHECK_FLOW_KEYS(desc, got, expected) \
> CHECK_ATTR(memcmp(&got, &expected, sizeof(got)) != 0, \
> desc, \
> @@ -49,6 +53,18 @@ struct ipv6_pkt {
> struct tcphdr tcp;
> } __packed;
>
> +struct ipv6_frag_pkt {
> + struct ethhdr eth;
> + struct ipv6hdr iph;
> + struct frag_hdr {
> + __u8 nexthdr;
> + __u8 reserved;
> + __be16 frag_off;
> + __be32 identification;
> + } ipf;
> + struct tcphdr tcp;
> +} __packed;
> +
> struct dvlan_ipv6_pkt {
> struct ethhdr eth;
> __u16 vlan_tci;
> @@ -65,9 +81,11 @@ struct test {
> struct ipv4_pkt ipv4;
> struct svlan_ipv4_pkt svlan_ipv4;
> struct ipv6_pkt ipv6;
> + struct ipv6_frag_pkt ipv6_frag;
> struct dvlan_ipv6_pkt dvlan_ipv6;
> } pkt;
> struct bpf_flow_keys keys;
> + __u32 flags;
> };
>
> #define VLAN_HLEN 4
> @@ -143,6 +161,102 @@ struct test tests[] = {
> .n_proto = __bpf_constant_htons(ETH_P_IPV6),
> },
> },
> + {
> + .name = "ipv4-frag",
> + .pkt.ipv4 = {
> + .eth.h_proto = __bpf_constant_htons(ETH_P_IP),
> + .iph.ihl = 5,
> + .iph.protocol = IPPROTO_TCP,
> + .iph.tot_len = __bpf_constant_htons(MAGIC_BYTES),
> + .iph.frag_off = __bpf_constant_htons(IP_MF),
> + .tcp.doff = 5,
> + .tcp.source = 80,
> + .tcp.dest = 8080,
> + },
> + .keys = {
> + .flags = FLOW_DISSECTOR_F_PARSE_1ST_FRAG,
> + .nhoff = ETH_HLEN,
> + .thoff = ETH_HLEN + sizeof(struct iphdr),
> + .addr_proto = ETH_P_IP,
> + .ip_proto = IPPROTO_TCP,
> + .n_proto = __bpf_constant_htons(ETH_P_IP),
> + .is_frag = true,
> + .is_first_frag = true,
> + .sport = 80,
> + .dport = 8080,
> + },
> + .flags = FLOW_DISSECTOR_F_PARSE_1ST_FRAG,
> + },
> + {
> + .name = "ipv4-no-frag",
> + .pkt.ipv4 = {
> + .eth.h_proto = __bpf_constant_htons(ETH_P_IP),
> + .iph.ihl = 5,
> + .iph.protocol = IPPROTO_TCP,
> + .iph.tot_len = __bpf_constant_htons(MAGIC_BYTES),
> + .iph.frag_off = __bpf_constant_htons(IP_MF),
> + .tcp.doff = 5,
> + .tcp.source = 80,
> + .tcp.dest = 8080,
> + },
> + .keys = {
> + .nhoff = ETH_HLEN,
> + .thoff = ETH_HLEN + sizeof(struct iphdr),
> + .addr_proto = ETH_P_IP,
> + .ip_proto = IPPROTO_TCP,
> + .n_proto = __bpf_constant_htons(ETH_P_IP),
> + .is_frag = true,
> + .is_first_frag = true,
> + },
> + },
> + {
> + .name = "ipv6-frag",
> + .pkt.ipv6_frag = {
> + .eth.h_proto = __bpf_constant_htons(ETH_P_IPV6),
> + .iph.nexthdr = IPPROTO_FRAGMENT,
> + .iph.payload_len = __bpf_constant_htons(MAGIC_BYTES),
> + .ipf.nexthdr = IPPROTO_TCP,
> + .tcp.doff = 5,
> + .tcp.source = 80,
> + .tcp.dest = 8080,
> + },
> + .keys = {
> + .flags = FLOW_DISSECTOR_F_PARSE_1ST_FRAG,
> + .nhoff = ETH_HLEN,
> + .thoff = ETH_HLEN + sizeof(struct ipv6hdr) +
> + sizeof(struct frag_hdr),
> + .addr_proto = ETH_P_IPV6,
> + .ip_proto = IPPROTO_TCP,
> + .n_proto = __bpf_constant_htons(ETH_P_IPV6),
> + .is_frag = true,
> + .is_first_frag = true,
> + .sport = 80,
> + .dport = 8080,
> + },
> + .flags = FLOW_DISSECTOR_F_PARSE_1ST_FRAG,
> + },
> + {
> + .name = "ipv6-no-frag",
> + .pkt.ipv6_frag = {
> + .eth.h_proto = __bpf_constant_htons(ETH_P_IPV6),
> + .iph.nexthdr = IPPROTO_FRAGMENT,
> + .iph.payload_len = __bpf_constant_htons(MAGIC_BYTES),
> + .ipf.nexthdr = IPPROTO_TCP,
> + .tcp.doff = 5,
> + .tcp.source = 80,
> + .tcp.dest = 8080,
> + },
> + .keys = {
> + .nhoff = ETH_HLEN,
> + .thoff = ETH_HLEN + sizeof(struct ipv6hdr) +
> + sizeof(struct frag_hdr),
> + .addr_proto = ETH_P_IPV6,
> + .ip_proto = IPPROTO_TCP,
> + .n_proto = __bpf_constant_htons(ETH_P_IPV6),
> + .is_frag = true,
> + .is_first_frag = true,
> + },
> + },
> };
>
> static int create_tap(const char *ifname)
> @@ -225,6 +339,13 @@ void test_flow_dissector(void)
> .data_size_in = sizeof(tests[i].pkt),
> .data_out = &flow_keys,
> };
> + static struct bpf_flow_keys ctx = {};
> +
> + if (tests[i].flags) {
> + tattr.ctx_in = &ctx;
> + tattr.ctx_size_in = sizeof(ctx);
> + ctx.flags = tests[i].flags;
> + }
>
> err = bpf_prog_test_run_xattr(&tattr);
> CHECK_ATTR(tattr.data_size_out != sizeof(flow_keys) ||
> @@ -251,10 +372,19 @@ void test_flow_dissector(void)
> CHECK(err, "ifup", "err %d errno %d\n", err, errno);
>
> for (i = 0; i < ARRAY_SIZE(tests); i++) {
> - struct bpf_flow_keys flow_keys = {};
> + /* Keep in sync with 'flags' from eth_get_headlen. */
> + __u32 eth_get_headlen_flags = FLOW_DISSECTOR_F_PARSE_1ST_FRAG;
> struct bpf_prog_test_run_attr tattr = {};
> + struct bpf_flow_keys flow_keys = {};
> __u32 key = 0;
>
> + /* For skb-less case we can't pass input flags; run
> + * only the tests that have a matching set of flags.
> + */
> +
> + if (tests[i].flags != eth_get_headlen_flags)
> + continue;
> +
> err = tx_tap(tap_fd, &tests[i].pkt, sizeof(tests[i].pkt));
> CHECK(err < 0, "tx_tap", "err %d errno %d\n", err, errno);
>
> diff --git a/tools/testing/selftests/bpf/progs/bpf_flow.c b/tools/testing/selftests/bpf/progs/bpf_flow.c
> index 5ae485a6af3f..0eabe5e57944 100644
> --- a/tools/testing/selftests/bpf/progs/bpf_flow.c
> +++ b/tools/testing/selftests/bpf/progs/bpf_flow.c
> @@ -153,7 +153,6 @@ static __always_inline int parse_ip_proto(struct __sk_buff *skb, __u8 proto)
> struct tcphdr *tcp, _tcp;
> struct udphdr *udp, _udp;
>
> - keys->ip_proto = proto;
> switch (proto) {
> case IPPROTO_ICMP:
> icmp = bpf_flow_dissect_get_header(skb, sizeof(*icmp), &_icmp);
> @@ -231,7 +230,6 @@ static __always_inline int parse_ipv6_proto(struct __sk_buff *skb, __u8 nexthdr)
> {
> struct bpf_flow_keys *keys = skb->flow_keys;
>
> - keys->ip_proto = nexthdr;
> switch (nexthdr) {
> case IPPROTO_HOPOPTS:
> case IPPROTO_DSTOPTS:
> @@ -266,6 +264,7 @@ PROG(IP)(struct __sk_buff *skb)
> keys->addr_proto = ETH_P_IP;
> keys->ipv4_src = iph->saddr;
> keys->ipv4_dst = iph->daddr;
> + keys->ip_proto = iph->protocol;
>
> keys->thoff += iph->ihl << 2;
> if (data + keys->thoff > data_end)
> @@ -273,13 +272,19 @@ PROG(IP)(struct __sk_buff *skb)
>
> if (iph->frag_off & bpf_htons(IP_MF | IP_OFFSET)) {
> keys->is_frag = true;
> - if (iph->frag_off & bpf_htons(IP_OFFSET))
> + if (iph->frag_off & bpf_htons(IP_OFFSET)) {
> /* From second fragment on, packets do not have headers
> * we can parse.
> */
> done = true;
> - else
> + } else {
> keys->is_first_frag = true;
> + /* No need to parse fragmented packet unless
> + * explicitly asked for.
> + */
> + if (!(keys->flags & FLOW_DISSECTOR_F_PARSE_1ST_FRAG))
> + done = true;
> + }
> }
>
> if (done)
> @@ -301,6 +306,7 @@ PROG(IPV6)(struct __sk_buff *skb)
> memcpy(&keys->ipv6_src, &ip6h->saddr, 2*sizeof(ip6h->saddr));
>
> keys->thoff += sizeof(struct ipv6hdr);
> + keys->ip_proto = ip6h->nexthdr;
>
> return parse_ipv6_proto(skb, ip6h->nexthdr);
> }
> @@ -317,7 +323,8 @@ PROG(IPV6OP)(struct __sk_buff *skb)
> /* hlen is in 8-octets and does not include the first 8 bytes
> * of the header
> */
> - skb->flow_keys->thoff += (1 + ip6h->hdrlen) << 3;
> + keys->thoff += (1 + ip6h->hdrlen) << 3;
> + keys->ip_proto = ip6h->nexthdr;
>
> return parse_ipv6_proto(skb, ip6h->nexthdr);
> }
> @@ -333,9 +340,18 @@ PROG(IPV6FR)(struct __sk_buff *skb)
>
> keys->thoff += sizeof(*fragh);
> keys->is_frag = true;
> - if (!(fragh->frag_off & bpf_htons(IP6_OFFSET)))
> + keys->ip_proto = fragh->nexthdr;
> +
> + if (!(fragh->frag_off & bpf_htons(IP6_OFFSET))) {
> keys->is_first_frag = true;
>
> + /* No need to parse fragmented packet unless
> + * explicitly asked for.
> + */
> + if (!(keys->flags & FLOW_DISSECTOR_F_PARSE_1ST_FRAG))
> + return export_flow_keys(keys, BPF_OK);
> + }
> +
> return parse_ipv6_proto(skb, fragh->nexthdr);
> }
>
> --
> 2.22.0.657.g960e92d24f-goog
>
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