From b08d4d3b6c0460306e8a0608413b201705200d33 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Tue, 23 Jun 2020 16:08:04 -0700 Subject: net: bpf: Add bpf_seq_afinfo in tcp_iter_state A new field bpf_seq_afinfo is added to tcp_iter_state to provide bpf tcp iterator afinfo. There are two reasons on why we did this. First, the current way to get afinfo from PDE_DATA does not work for bpf iterator as its seq_file inode does not conform to /proc/net/{tcp,tcp6} inode structures. More specifically, anonymous bpf iterator will use an anonymous inode which is shared in the system and we cannot change inode private data structure at all. Second, bpf iterator for tcp/tcp6 wants to traverse all tcp and tcp6 sockets in one pass and bpf program can control whether they want to skip one sk_family or not. Having a different afinfo with family AF_UNSPEC make it easier to understand in the code. This patch does not change /proc/net/{tcp,tcp6} behavior as the bpf_seq_afinfo will be NULL for these two proc files. Signed-off-by: Yonghong Song Signed-off-by: Alexei Starovoitov Acked-by: Martin KaFai Lau Link: https://lore.kernel.org/bpf/20200623230804.3987829-1-yhs@fb.com --- net/ipv4/tcp_ipv4.c | 30 ++++++++++++++++++++++++------ 1 file changed, 24 insertions(+), 6 deletions(-) (limited to 'net/ipv4/tcp_ipv4.c') diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index ad6435ba6d72..9cb65ee4ec63 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -2211,13 +2211,18 @@ EXPORT_SYMBOL(tcp_v4_destroy_sock); */ static void *listening_get_next(struct seq_file *seq, void *cur) { - struct tcp_seq_afinfo *afinfo = PDE_DATA(file_inode(seq->file)); + struct tcp_seq_afinfo *afinfo; struct tcp_iter_state *st = seq->private; struct net *net = seq_file_net(seq); struct inet_listen_hashbucket *ilb; struct hlist_nulls_node *node; struct sock *sk = cur; + if (st->bpf_seq_afinfo) + afinfo = st->bpf_seq_afinfo; + else + afinfo = PDE_DATA(file_inode(seq->file)); + if (!sk) { get_head: ilb = &tcp_hashinfo.listening_hash[st->bucket]; @@ -2235,7 +2240,8 @@ get_sk: sk_nulls_for_each_from(sk, node) { if (!net_eq(sock_net(sk), net)) continue; - if (sk->sk_family == afinfo->family) + if (afinfo->family == AF_UNSPEC || + sk->sk_family == afinfo->family) return sk; } spin_unlock(&ilb->lock); @@ -2272,11 +2278,16 @@ static inline bool empty_bucket(const struct tcp_iter_state *st) */ static void *established_get_first(struct seq_file *seq) { - struct tcp_seq_afinfo *afinfo = PDE_DATA(file_inode(seq->file)); + struct tcp_seq_afinfo *afinfo; struct tcp_iter_state *st = seq->private; struct net *net = seq_file_net(seq); void *rc = NULL; + if (st->bpf_seq_afinfo) + afinfo = st->bpf_seq_afinfo; + else + afinfo = PDE_DATA(file_inode(seq->file)); + st->offset = 0; for (; st->bucket <= tcp_hashinfo.ehash_mask; ++st->bucket) { struct sock *sk; @@ -2289,7 +2300,8 @@ static void *established_get_first(struct seq_file *seq) spin_lock_bh(lock); sk_nulls_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) { - if (sk->sk_family != afinfo->family || + if ((afinfo->family != AF_UNSPEC && + sk->sk_family != afinfo->family) || !net_eq(sock_net(sk), net)) { continue; } @@ -2304,19 +2316,25 @@ out: static void *established_get_next(struct seq_file *seq, void *cur) { - struct tcp_seq_afinfo *afinfo = PDE_DATA(file_inode(seq->file)); + struct tcp_seq_afinfo *afinfo; struct sock *sk = cur; struct hlist_nulls_node *node; struct tcp_iter_state *st = seq->private; struct net *net = seq_file_net(seq); + if (st->bpf_seq_afinfo) + afinfo = st->bpf_seq_afinfo; + else + afinfo = PDE_DATA(file_inode(seq->file)); + ++st->num; ++st->offset; sk = sk_nulls_next(sk); sk_nulls_for_each_from(sk, node) { - if (sk->sk_family == afinfo->family && + if ((afinfo->family == AF_UNSPEC || + sk->sk_family == afinfo->family) && net_eq(sock_net(sk), net)) return sk; } -- cgit v1.2.3 From 52d87d5f6418ba1b8b449ed5eea1532664896851 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Tue, 23 Jun 2020 16:08:05 -0700 Subject: net: bpf: Implement bpf iterator for tcp The bpf iterator for tcp is implemented. Both tcp4 and tcp6 sockets will be traversed. It is up to bpf program to filter for tcp4 or tcp6 only, or both families of sockets. Signed-off-by: Yonghong Song Signed-off-by: Alexei Starovoitov Acked-by: Martin KaFai Lau Link: https://lore.kernel.org/bpf/20200623230805.3987959-1-yhs@fb.com --- net/ipv4/tcp_ipv4.c | 123 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 123 insertions(+) (limited to 'net/ipv4/tcp_ipv4.c') diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 9cb65ee4ec63..ea0df9fd7618 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -2613,6 +2613,74 @@ out: return 0; } +#ifdef CONFIG_BPF_SYSCALL +struct bpf_iter__tcp { + __bpf_md_ptr(struct bpf_iter_meta *, meta); + __bpf_md_ptr(struct sock_common *, sk_common); + uid_t uid __aligned(8); +}; + +static int tcp_prog_seq_show(struct bpf_prog *prog, struct bpf_iter_meta *meta, + struct sock_common *sk_common, uid_t uid) +{ + struct bpf_iter__tcp ctx; + + meta->seq_num--; /* skip SEQ_START_TOKEN */ + ctx.meta = meta; + ctx.sk_common = sk_common; + ctx.uid = uid; + return bpf_iter_run_prog(prog, &ctx); +} + +static int bpf_iter_tcp_seq_show(struct seq_file *seq, void *v) +{ + struct bpf_iter_meta meta; + struct bpf_prog *prog; + struct sock *sk = v; + uid_t uid; + + if (v == SEQ_START_TOKEN) + return 0; + + if (sk->sk_state == TCP_TIME_WAIT) { + uid = 0; + } else if (sk->sk_state == TCP_NEW_SYN_RECV) { + const struct request_sock *req = v; + + uid = from_kuid_munged(seq_user_ns(seq), + sock_i_uid(req->rsk_listener)); + } else { + uid = from_kuid_munged(seq_user_ns(seq), sock_i_uid(sk)); + } + + meta.seq = seq; + prog = bpf_iter_get_info(&meta, false); + return tcp_prog_seq_show(prog, &meta, v, uid); +} + +static void bpf_iter_tcp_seq_stop(struct seq_file *seq, void *v) +{ + struct bpf_iter_meta meta; + struct bpf_prog *prog; + + if (!v) { + meta.seq = seq; + prog = bpf_iter_get_info(&meta, true); + if (prog) + (void)tcp_prog_seq_show(prog, &meta, v, 0); + } + + tcp_seq_stop(seq, v); +} + +static const struct seq_operations bpf_iter_tcp_seq_ops = { + .show = bpf_iter_tcp_seq_show, + .start = tcp_seq_start, + .next = tcp_seq_next, + .stop = bpf_iter_tcp_seq_stop, +}; +#endif + static const struct seq_operations tcp4_seq_ops = { .show = tcp4_seq_show, .start = tcp_seq_start, @@ -2844,8 +2912,63 @@ static struct pernet_operations __net_initdata tcp_sk_ops = { .exit_batch = tcp_sk_exit_batch, }; +#if defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS) +DEFINE_BPF_ITER_FUNC(tcp, struct bpf_iter_meta *meta, + struct sock_common *sk_common, uid_t uid) + +static int bpf_iter_init_tcp(void *priv_data) +{ + struct tcp_iter_state *st = priv_data; + struct tcp_seq_afinfo *afinfo; + int ret; + + afinfo = kmalloc(sizeof(*afinfo), GFP_USER | __GFP_NOWARN); + if (!afinfo) + return -ENOMEM; + + afinfo->family = AF_UNSPEC; + st->bpf_seq_afinfo = afinfo; + ret = bpf_iter_init_seq_net(priv_data); + if (ret) + kfree(afinfo); + return ret; +} + +static void bpf_iter_fini_tcp(void *priv_data) +{ + struct tcp_iter_state *st = priv_data; + + kfree(st->bpf_seq_afinfo); + bpf_iter_fini_seq_net(priv_data); +} + +static const struct bpf_iter_reg tcp_reg_info = { + .target = "tcp", + .seq_ops = &bpf_iter_tcp_seq_ops, + .init_seq_private = bpf_iter_init_tcp, + .fini_seq_private = bpf_iter_fini_tcp, + .seq_priv_size = sizeof(struct tcp_iter_state), + .ctx_arg_info_size = 1, + .ctx_arg_info = { + { offsetof(struct bpf_iter__tcp, sk_common), + PTR_TO_BTF_ID_OR_NULL }, + }, +}; + +static void __init bpf_iter_register(void) +{ + if (bpf_iter_reg_target(&tcp_reg_info)) + pr_warn("Warning: could not register bpf iterator tcp\n"); +} + +#endif + void __init tcp_v4_init(void) { if (register_pernet_subsys(&tcp_sk_ops)) panic("Failed to create the TCP control socket.\n"); + +#if defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS) + bpf_iter_register(); +#endif } -- cgit v1.2.3