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Message-ID: <ZKWq142tp/tI6NI3@google.com>
Date: Wed, 5 Jul 2023 10:39:35 -0700
From: Stanislav Fomichev <sdf@...gle.com>
To: Larysa Zaremba <larysa.zaremba@...el.com>
Cc: bpf@...r.kernel.org, ast@...nel.org, daniel@...earbox.net,
andrii@...nel.org, martin.lau@...ux.dev, song@...nel.org, yhs@...com,
john.fastabend@...il.com, kpsingh@...nel.org, haoluo@...gle.com,
jolsa@...nel.org, David Ahern <dsahern@...il.com>, Jakub Kicinski <kuba@...nel.org>,
Willem de Bruijn <willemb@...gle.com>, Jesper Dangaard Brouer <brouer@...hat.com>,
Anatoly Burakov <anatoly.burakov@...el.com>, Alexander Lobakin <alexandr.lobakin@...el.com>,
Magnus Karlsson <magnus.karlsson@...il.com>, Maryam Tahhan <mtahhan@...hat.com>,
xdp-hints@...-project.net, netdev@...r.kernel.org
Subject: Re: [PATCH bpf-next v2 18/20] selftests/bpf: Use AF_INET for TX in xdp_metadata
On 07/03, Larysa Zaremba wrote:
> The easiest way to simulate stripped VLAN tag in veth is to send a packet
> from VLAN interface, attached to veth. Unfortunately, this approach is
> incompatible with AF_XDP on TX side, because VLAN interfaces do not have
> such feature.
>
> Replace AF_XDP packet generation with sending the same datagram via
> AF_INET socket.
>
> This does not change the packet contents or hints values with one notable
> exception: rx_hash_type, which previously was expected to be 0, now is
> expected be at least XDP_RSS_TYPE_L4.
>
> Also, usage of AF_INET requires a little more complicated namespace setup,
> therefore open_netns() helper function is divided into smaller reusable
> pieces.
Ack, it's probably OK for now, but, FYI, I'm trying to extend this part
with TX metadata:
https://lore.kernel.org/bpf/20230621170244.1283336-10-sdf@google.com/
So probably long-term I'll switch it back to AF_XDP but will add
support for requesting vlan TX "offload" from the veth.
> Signed-off-by: Larysa Zaremba <larysa.zaremba@...el.com>
> ---
> tools/testing/selftests/bpf/network_helpers.c | 37 +++-
> tools/testing/selftests/bpf/network_helpers.h | 3 +
> .../selftests/bpf/prog_tests/xdp_metadata.c | 175 +++++++-----------
> 3 files changed, 98 insertions(+), 117 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/network_helpers.c b/tools/testing/selftests/bpf/network_helpers.c
> index a105c0cd008a..19463230ece5 100644
> --- a/tools/testing/selftests/bpf/network_helpers.c
> +++ b/tools/testing/selftests/bpf/network_helpers.c
> @@ -386,28 +386,51 @@ char *ping_command(int family)
> return "ping";
> }
>
> +int get_cur_netns(void)
> +{
> + int nsfd;
> +
> + nsfd = open("/proc/self/ns/net", O_RDONLY);
> + ASSERT_GE(nsfd, 0, "open /proc/self/ns/net");
> + return nsfd;
> +}
> +
> +int get_netns(const char *name)
> +{
> + char nspath[PATH_MAX];
> + int nsfd;
> +
> + snprintf(nspath, sizeof(nspath), "%s/%s", "/var/run/netns", name);
> + nsfd = open(nspath, O_RDONLY | O_CLOEXEC);
> + ASSERT_GE(nsfd, 0, "open /proc/self/ns/net");
> + return nsfd;
> +}
> +
> +int set_netns(int netns_fd)
> +{
> + return setns(netns_fd, CLONE_NEWNET);
> +}
We have open_netns/close_netns in network_helpers.h that provide similar
functionality, let's use them instead?
> +
> struct nstoken {
> int orig_netns_fd;
> };
>
> struct nstoken *open_netns(const char *name)
> {
> + struct nstoken *token;
> int nsfd;
> - char nspath[PATH_MAX];
> int err;
> - struct nstoken *token;
>
> token = calloc(1, sizeof(struct nstoken));
> if (!ASSERT_OK_PTR(token, "malloc token"))
> return NULL;
>
> - token->orig_netns_fd = open("/proc/self/ns/net", O_RDONLY);
> - if (!ASSERT_GE(token->orig_netns_fd, 0, "open /proc/self/ns/net"))
> + token->orig_netns_fd = get_cur_netns();
> + if (token->orig_netns_fd < 0)
> goto fail;
>
> - snprintf(nspath, sizeof(nspath), "%s/%s", "/var/run/netns", name);
> - nsfd = open(nspath, O_RDONLY | O_CLOEXEC);
> - if (!ASSERT_GE(nsfd, 0, "open netns fd"))
> + nsfd = get_netns(name);
> + if (nsfd < 0)
> goto fail;
>
> err = setns(nsfd, CLONE_NEWNET);
> diff --git a/tools/testing/selftests/bpf/network_helpers.h b/tools/testing/selftests/bpf/network_helpers.h
> index 694185644da6..b18b9619595c 100644
> --- a/tools/testing/selftests/bpf/network_helpers.h
> +++ b/tools/testing/selftests/bpf/network_helpers.h
> @@ -58,6 +58,8 @@ int make_sockaddr(int family, const char *addr_str, __u16 port,
> char *ping_command(int family);
> int get_socket_local_port(int sock_fd);
>
> +int get_cur_netns(void);
> +int get_netns(const char *name);
> struct nstoken;
> /**
> * open_netns() - Switch to specified network namespace by name.
> @@ -67,4 +69,5 @@ struct nstoken;
> */
> struct nstoken *open_netns(const char *name);
> void close_netns(struct nstoken *token);
> +int set_netns(int netns_fd);
> #endif
> diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_metadata.c b/tools/testing/selftests/bpf/prog_tests/xdp_metadata.c
> index 626c461fa34d..53b32a641e8e 100644
> --- a/tools/testing/selftests/bpf/prog_tests/xdp_metadata.c
> +++ b/tools/testing/selftests/bpf/prog_tests/xdp_metadata.c
> @@ -20,7 +20,7 @@
>
> #define UDP_PAYLOAD_BYTES 4
>
> -#define AF_XDP_SOURCE_PORT 1234
> +#define UDP_SOURCE_PORT 1234
> #define AF_XDP_CONSUMER_PORT 8080
>
> #define UMEM_NUM 16
> @@ -33,6 +33,12 @@
> #define RX_ADDR "10.0.0.2"
> #define PREFIX_LEN "8"
> #define FAMILY AF_INET
> +#define TX_NETNS_NAME "xdp_metadata_tx"
> +#define RX_NETNS_NAME "xdp_metadata_rx"
> +#define TX_MAC "00:00:00:00:00:01"
> +#define RX_MAC "00:00:00:00:00:02"
> +
> +#define XDP_RSS_TYPE_L4 BIT(3)
>
> struct xsk {
> void *umem_area;
> @@ -119,90 +125,28 @@ static void close_xsk(struct xsk *xsk)
> munmap(xsk->umem_area, UMEM_SIZE);
> }
>
> -static void ip_csum(struct iphdr *iph)
> +static int generate_packet_udp(void)
> {
> - __u32 sum = 0;
> - __u16 *p;
> - int i;
> -
> - iph->check = 0;
> - p = (void *)iph;
> - for (i = 0; i < sizeof(*iph) / sizeof(*p); i++)
> - sum += p[i];
> -
> - while (sum >> 16)
> - sum = (sum & 0xffff) + (sum >> 16);
> -
> - iph->check = ~sum;
> -}
> -
> -static int generate_packet(struct xsk *xsk, __u16 dst_port)
> -{
> - struct xdp_desc *tx_desc;
> - struct udphdr *udph;
> - struct ethhdr *eth;
> - struct iphdr *iph;
> - void *data;
> - __u32 idx;
> - int ret;
> -
> - ret = xsk_ring_prod__reserve(&xsk->tx, 1, &idx);
> - if (!ASSERT_EQ(ret, 1, "xsk_ring_prod__reserve"))
> - return -1;
> -
> - tx_desc = xsk_ring_prod__tx_desc(&xsk->tx, idx);
> - tx_desc->addr = idx % (UMEM_NUM / 2) * UMEM_FRAME_SIZE;
> - printf("%p: tx_desc[%u]->addr=%llx\n", xsk, idx, tx_desc->addr);
> - data = xsk_umem__get_data(xsk->umem_area, tx_desc->addr);
> -
> - eth = data;
> - iph = (void *)(eth + 1);
> - udph = (void *)(iph + 1);
> -
> - memcpy(eth->h_dest, "\x00\x00\x00\x00\x00\x02", ETH_ALEN);
> - memcpy(eth->h_source, "\x00\x00\x00\x00\x00\x01", ETH_ALEN);
> - eth->h_proto = htons(ETH_P_IP);
> -
> - iph->version = 0x4;
> - iph->ihl = 0x5;
> - iph->tos = 0x9;
> - iph->tot_len = htons(sizeof(*iph) + sizeof(*udph) + UDP_PAYLOAD_BYTES);
> - iph->id = 0;
> - iph->frag_off = 0;
> - iph->ttl = 0;
> - iph->protocol = IPPROTO_UDP;
> - ASSERT_EQ(inet_pton(FAMILY, TX_ADDR, &iph->saddr), 1, "inet_pton(TX_ADDR)");
> - ASSERT_EQ(inet_pton(FAMILY, RX_ADDR, &iph->daddr), 1, "inet_pton(RX_ADDR)");
> - ip_csum(iph);
> -
> - udph->source = htons(AF_XDP_SOURCE_PORT);
> - udph->dest = htons(dst_port);
> - udph->len = htons(sizeof(*udph) + UDP_PAYLOAD_BYTES);
> - udph->check = 0;
> -
> - memset(udph + 1, 0xAA, UDP_PAYLOAD_BYTES);
> -
> - tx_desc->len = sizeof(*eth) + sizeof(*iph) + sizeof(*udph) + UDP_PAYLOAD_BYTES;
> - xsk_ring_prod__submit(&xsk->tx, 1);
> -
> - ret = sendto(xsk_socket__fd(xsk->socket), NULL, 0, MSG_DONTWAIT, NULL, 0);
> - if (!ASSERT_GE(ret, 0, "sendto"))
> - return ret;
> -
> - return 0;
> -}
> -
> -static void complete_tx(struct xsk *xsk)
> -{
> - __u32 idx;
> - __u64 addr;
> -
> - if (ASSERT_EQ(xsk_ring_cons__peek(&xsk->comp, 1, &idx), 1, "xsk_ring_cons__peek")) {
> - addr = *xsk_ring_cons__comp_addr(&xsk->comp, idx);
> -
> - printf("%p: complete tx idx=%u addr=%llx\n", xsk, idx, addr);
> - xsk_ring_cons__release(&xsk->comp, 1);
> - }
> + char udp_payload[UDP_PAYLOAD_BYTES];
> + struct sockaddr_in rx_addr;
> + int sock_fd, err = 0;
> +
> + /* Build a packet */
> + memset(udp_payload, 0xAA, UDP_PAYLOAD_BYTES);
> + rx_addr.sin_addr.s_addr = inet_addr(RX_ADDR);
> + rx_addr.sin_family = AF_INET;
> + rx_addr.sin_port = htons(UDP_SOURCE_PORT);
> +
> + sock_fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
> + if (!ASSERT_GE(sock_fd, 0, "socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)"))
> + return sock_fd;
> +
> + err = sendto(sock_fd, udp_payload, UDP_PAYLOAD_BYTES, MSG_DONTWAIT,
> + (void *)&rx_addr, sizeof(rx_addr));
> + ASSERT_GE(err, 0, "sendto");
> +
> + close(sock_fd);
> + return err;
> }
>
> static void refill_rx(struct xsk *xsk, __u64 addr)
> @@ -268,7 +212,8 @@ static int verify_xsk_metadata(struct xsk *xsk)
> if (!ASSERT_NEQ(meta->rx_hash, 0, "rx_hash"))
> return -1;
>
> - ASSERT_EQ(meta->rx_hash_type, 0, "rx_hash_type");
> + if (!ASSERT_NEQ(meta->rx_hash_type & XDP_RSS_TYPE_L4, 0, "rx_hash_type"))
> + return -1;
>
> xsk_ring_cons__release(&xsk->rx, 1);
> refill_rx(xsk, comp_addr);
> @@ -281,40 +226,46 @@ void test_xdp_metadata(void)
> struct xdp_metadata2 *bpf_obj2 = NULL;
> struct xdp_metadata *bpf_obj = NULL;
> struct bpf_program *new_prog, *prog;
> - struct nstoken *tok = NULL;
> + int prev_netns, rx_netns, tx_netns;
> __u32 queue_id = QUEUE_ID;
> struct bpf_map *prog_arr;
> - struct xsk tx_xsk = {};
> struct xsk rx_xsk = {};
> __u32 val, key = 0;
> int retries = 10;
> int rx_ifindex;
> - int tx_ifindex;
> int sock_fd;
> int ret;
>
> - /* Setup new networking namespace, with a veth pair. */
> + /* Setup new networking namespaces, with a veth pair. */
>
> - SYS(out, "ip netns add xdp_metadata");
> - tok = open_netns("xdp_metadata");
> + SYS(out, "ip netns add " TX_NETNS_NAME);
> + SYS(out, "ip netns add " RX_NETNS_NAME);
> + prev_netns = get_cur_netns();
> + tx_netns = get_netns(TX_NETNS_NAME);
> + rx_netns = get_netns(RX_NETNS_NAME);
> + if (prev_netns < 0 || tx_netns < 0 || rx_netns < 0)
> + goto close_ns;
> +
> + set_netns(tx_netns);
> SYS(out, "ip link add numtxqueues 1 numrxqueues 1 " TX_NAME
> " type veth peer " RX_NAME " numtxqueues 1 numrxqueues 1");
> - SYS(out, "ip link set dev " TX_NAME " address 00:00:00:00:00:01");
> - SYS(out, "ip link set dev " RX_NAME " address 00:00:00:00:00:02");
> + SYS(out, "ip link set " RX_NAME " netns " RX_NETNS_NAME);
> +
> + SYS(out, "ip link set dev " TX_NAME " address " TX_MAC);
> SYS(out, "ip link set dev " TX_NAME " up");
> - SYS(out, "ip link set dev " RX_NAME " up");
> SYS(out, "ip addr add " TX_ADDR "/" PREFIX_LEN " dev " TX_NAME);
> - SYS(out, "ip addr add " RX_ADDR "/" PREFIX_LEN " dev " RX_NAME);
>
> + /* Avoid ARP calls */
> + SYS(out, "ip -4 neigh add " RX_ADDR " lladdr " RX_MAC " dev " TX_NAME);
> +
> + set_netns(rx_netns);
> + SYS(out, "ip link set dev " RX_NAME " address " RX_MAC);
> + SYS(out, "ip link set dev " RX_NAME " up");
> + SYS(out, "ip addr add " RX_ADDR "/" PREFIX_LEN " dev " RX_NAME);
> rx_ifindex = if_nametoindex(RX_NAME);
> - tx_ifindex = if_nametoindex(TX_NAME);
>
> /* Setup separate AF_XDP for TX and RX interfaces. */
>
> - ret = open_xsk(tx_ifindex, &tx_xsk);
> - if (!ASSERT_OK(ret, "open_xsk(TX_NAME)"))
> - goto out;
> -
> ret = open_xsk(rx_ifindex, &rx_xsk);
> if (!ASSERT_OK(ret, "open_xsk(RX_NAME)"))
> goto out;
> @@ -355,17 +306,16 @@ void test_xdp_metadata(void)
> goto out;
>
> /* Send packet destined to RX AF_XDP socket. */
> - if (!ASSERT_GE(generate_packet(&tx_xsk, AF_XDP_CONSUMER_PORT), 0,
> - "generate AF_XDP_CONSUMER_PORT"))
> + set_netns(tx_netns);
> + if (!ASSERT_GE(generate_packet_udp(), 0, "generate UDP packet"))
> goto out;
>
> /* Verify AF_XDP RX packet has proper metadata. */
> + set_netns(rx_netns);
> if (!ASSERT_GE(verify_xsk_metadata(&rx_xsk), 0,
> "verify_xsk_metadata"))
> goto out;
>
> - complete_tx(&tx_xsk);
> -
> /* Make sure freplace correctly picks up original bound device
> * and doesn't crash.
> */
> @@ -384,10 +334,11 @@ void test_xdp_metadata(void)
> goto out;
>
> /* Send packet to trigger . */
> - if (!ASSERT_GE(generate_packet(&tx_xsk, AF_XDP_CONSUMER_PORT), 0,
> - "generate freplace packet"))
> + set_netns(tx_netns);
> + if (!ASSERT_GE(generate_packet_udp(), 0, "generate freplace packet"))
> goto out;
>
> + set_netns(rx_netns);
> while (!retries--) {
> if (bpf_obj2->bss->called)
> break;
> @@ -397,10 +348,14 @@ void test_xdp_metadata(void)
>
> out:
> close_xsk(&rx_xsk);
> - close_xsk(&tx_xsk);
> xdp_metadata2__destroy(bpf_obj2);
> xdp_metadata__destroy(bpf_obj);
> - if (tok)
> - close_netns(tok);
> - SYS_NOFAIL("ip netns del xdp_metadata");
> + set_netns(prev_netns);
> +close_ns:
> + close(prev_netns);
> + close(tx_netns);
> + close(rx_netns);
> +
> + SYS_NOFAIL("ip netns del " RX_NETNS_NAME);
> + SYS_NOFAIL("ip netns del " TX_NETNS_NAME);
> }
> --
> 2.41.0
>
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