From: Alban Crequy <al...@kinvolk.io> This shows how a sockops program could be restricted to a specific network namespace. The sockops program looks at the current netns via (struct bpf_sock_ops)->netns_ino and checks if the value matches the configuration in the new BPF map "sock_netns".
The test program ./test_sockmap accepts a new parameter "--netns"; the default value is the current netns found by stat() on /proc/self/ns/net, so the previous tests still pass: sudo ./test_sockmap ... Summary: 412 PASSED 0 FAILED ... Summary: 824 PASSED 0 FAILED I run my additional test in the following way: NETNS=$(readlink /proc/self/ns/net | sed 's/^net:\[\(.*\)\]$/\1/') CGR=/sys/fs/cgroup/unified/user.slice/user-1000.slice/session-5.scope/ sudo ./test_sockmap --cgroup $CGR --netns $NETNS & cat /sys/kernel/debug/tracing/trace_pipe echo foo | nc -l 127.0.0.1 8080 & echo bar | nc 127.0.0.1 8080 => the connection goes through the sockmap When testing with a wrong $NETNS, I get the trace_pipe log: > not binding connection on netns 4026531992 Signed-off-by: Alban Crequy <al...@kinvolk.io> --- Changes since v1: - tools/include/uapi/linux/bpf.h: update with netns_dev - tools/testing/selftests/bpf/test_sockmap_kern.h: print debugs with both netns_dev and netns_ino Changes since v2: - update commitmsg to refer to netns_ino --- tools/testing/selftests/bpf/test_sockmap.c | 38 +++++++++++++++++-- .../testing/selftests/bpf/test_sockmap_kern.h | 22 +++++++++++ 2 files changed, 57 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/bpf/test_sockmap.c b/tools/testing/selftests/bpf/test_sockmap.c index 3845144e2c91..5a1b9c96fca1 100644 --- a/tools/testing/selftests/bpf/test_sockmap.c +++ b/tools/testing/selftests/bpf/test_sockmap.c @@ -2,6 +2,7 @@ // Copyright (c) 2017-2018 Covalent IO, Inc. http://covalent.io #include <stdio.h> #include <stdlib.h> +#include <stdint.h> #include <sys/socket.h> #include <sys/ioctl.h> #include <sys/select.h> @@ -21,6 +22,7 @@ #include <sys/resource.h> #include <sys/types.h> #include <sys/sendfile.h> +#include <sys/stat.h> #include <linux/netlink.h> #include <linux/socket.h> @@ -63,8 +65,8 @@ int s1, s2, c1, c2, p1, p2; int test_cnt; int passed; int failed; -int map_fd[8]; -struct bpf_map *maps[8]; +int map_fd[9]; +struct bpf_map *maps[9]; int prog_fd[11]; int txmsg_pass; @@ -84,6 +86,7 @@ int txmsg_ingress; int txmsg_skb; int ktls; int peek_flag; +uint64_t netns_opt; static const struct option long_options[] = { {"help", no_argument, NULL, 'h' }, @@ -111,6 +114,7 @@ static const struct option long_options[] = { {"txmsg_skb", no_argument, &txmsg_skb, 1 }, {"ktls", no_argument, &ktls, 1 }, {"peek", no_argument, &peek_flag, 1 }, + {"netns", required_argument, NULL, 'n'}, {0, 0, NULL, 0 } }; @@ -1585,6 +1589,7 @@ char *map_names[] = { "sock_bytes", "sock_redir_flags", "sock_skb_opts", + "sock_netns", }; int prog_attach_type[] = { @@ -1619,6 +1624,8 @@ static int populate_progs(char *bpf_file) struct bpf_object *obj; int i = 0; long err; + struct stat netns_sb; + uint64_t netns_ino; obj = bpf_object__open(bpf_file); err = libbpf_get_error(obj); @@ -1655,6 +1662,28 @@ static int populate_progs(char *bpf_file) } } + if (netns_opt == 0) { + err = stat("/proc/self/ns/net", &netns_sb); + if (err) { + fprintf(stderr, + "ERROR: cannot stat network namespace: %ld (%s)\n", + err, strerror(errno)); + return -1; + } + netns_ino = netns_sb.st_ino; + } else { + netns_ino = netns_opt; + } + i = 1; + err = bpf_map_update_elem(map_fd[8], &netns_ino, &i, BPF_ANY); + if (err) { + fprintf(stderr, + "ERROR: bpf_map_update_elem (netns): %ld (%s)\n", + err, strerror(errno)); + return -1; + } + + return 0; } @@ -1738,7 +1767,7 @@ int main(int argc, char **argv) if (argc < 2) return test_suite(-1); - while ((opt = getopt_long(argc, argv, ":dhvc:r:i:l:t:p:q:", + while ((opt = getopt_long(argc, argv, ":dhvc:r:i:l:t:p:q:n:", long_options, &longindex)) != -1) { switch (opt) { case 's': @@ -1805,6 +1834,9 @@ int main(int argc, char **argv) return -1; } break; + case 'n': + netns_opt = strtoull(optarg, NULL, 10); + break; case 0: break; case 'h': diff --git a/tools/testing/selftests/bpf/test_sockmap_kern.h b/tools/testing/selftests/bpf/test_sockmap_kern.h index e7639f66a941..317406dad6cf 100644 --- a/tools/testing/selftests/bpf/test_sockmap_kern.h +++ b/tools/testing/selftests/bpf/test_sockmap_kern.h @@ -91,6 +91,13 @@ struct bpf_map_def SEC("maps") sock_skb_opts = { .max_entries = 1 }; +struct bpf_map_def SEC("maps") sock_netns = { + .type = BPF_MAP_TYPE_HASH, + .key_size = sizeof(__u64), + .value_size = sizeof(int), + .max_entries = 16 +}; + SEC("sk_skb1") int bpf_prog1(struct __sk_buff *skb) { @@ -132,9 +139,24 @@ int bpf_sockmap(struct bpf_sock_ops *skops) { __u32 lport, rport; int op, err = 0, index, key, ret; + int i = 0; + __u64 netns_dev, netns_ino; + int *allowed; op = (int) skops->op; + netns_dev = skops->netns_dev; + netns_ino = skops->netns_ino; + bpf_printk("bpf_sockmap: netns_dev = %lu netns_ino = %lu\n", + netns_dev, netns_ino); + + // Only allow sockmap connection on the configured network namespace + allowed = bpf_map_lookup_elem(&sock_netns, &netns_ino); + if (allowed == NULL || *allowed == 0) { + bpf_printk("not binding connection on netns_ino %lu\n", + netns_ino); + return 0; + } switch (op) { case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB: -- 2.21.0
