Merge branch 'bpf_iter_tcp_udp'

Yonghong Song says:

====================
bpf iterator implments traversal of kernel data structures and these
data structures are passed to a bpf program for processing.
This gives great flexibility for users to examine kernel data
structure without using e.g. /proc/net which has limited and
fixed format.

Commit 138d0be35b14 ("net: bpf: Add netlink and ipv6_route bpf_iter targets")
implemented bpf iterators for netlink and ipv6_route.
This patch set intends to implement bpf iterators for tcp and udp.

Currently, /proc/net/tcp is used to print tcp4 stats and /proc/net/tcp6
is used to print tcp6 stats. /proc/net/udp[6] have similar usage model.
In contrast, only one tcp iterator is implemented and it is bpf program
resposibility to filter based on socket family. The same is for udp.
This will avoid another unnecessary traversal pass if users want
to check both tcp4 and tcp6.

Several helpers are also implemented in this patch
  bpf_skc_to_{tcp, tcp6, tcp_timewait, tcp_request, udp6}_sock
The argument for these helpers is not a fixed btf_id. For example,
  bpf_skc_to_tcp(struct sock_common *), or
  bpf_skc_to_tcp(struct sock *), or
  bpf_skc_to_tcp(struct inet_sock *), ...
are all valid. At runtime, the helper will check whether pointer cast
is legal or not. Please see Patch #5 for details.

Since btf_id's for both arguments and return value are known at
build time, the btf_id's are pre-computed once vmlinux btf becomes
valid. Jiri's "adding d_path helper" patch set
  https://lore.kernel.org/bpf/20200616100512.2168860-1-jolsa@kernel.org/T/
provides a way to pre-compute btf id during vmlinux build time.
This can be applied here as well. A followup patch can convert
to build time btf id computation after Jiri's patch landed.

Changelogs:
  v4 -> v5:
    - fix bpf_skc_to_udp6_sock helper as besides sk_protocol, sk_family,
      sk_type == SOCK_DGRAM is also needed to differentiate from
      SOCK_RAW (Eric)
  v3 -> v4:
    - fix bpf_skc_to_{tcp_timewait, tcp_request}_sock helper implementation
      as just checking sk->sk_state is not enough (Martin)
    - fix a few kernel test robot reported failures
    - move bpf_tracing_net.h from libbpf to selftests (Andrii)
    - remove __weak attribute from selftests CONFIG_HZ variables (Andrii)
  v2 -> v3:
    - change sock_cast*/SOCK_CAST* names to btf_sock* names for generality (Martin)
    - change gpl_license to false (Martin)
    - fix helper to cast to tcp timewait/request socket. (Martin)
  v1 -> v2:
    - guard init_sock_cast_types() defination properly with CONFIG_NET (Martin)
    - reuse the btf_ids, computed for new helper argument, for return
      values (Martin)
    - using BTF_TYPE_EMIT to express intent of btf type generation (Andrii)
    - abstract out common net macros into bpf_tracing_net.h (Andrii)
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 234 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_tcp4.c b/tools/testing/selftests/bpf/progs/bpf_iter_tcp4.c
new file mode 100644
index 000000000000..30fd587cb325
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_tcp4.c
@@ -0,0 +1,234 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#include "bpf_iter.h"
+#include "bpf_tracing_net.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_endian.h>
+
+char _license[] SEC("license") = "GPL";
+
+static int hlist_unhashed_lockless(const struct hlist_node *h)
+{
+        return !(h->pprev);
+}
+
+static int timer_pending(const struct timer_list * timer)
+{
+	return !hlist_unhashed_lockless(&timer->entry);
+}
+
+extern unsigned CONFIG_HZ __kconfig;
+
+#define USER_HZ		100
+#define NSEC_PER_SEC	1000000000ULL
+static clock_t jiffies_to_clock_t(unsigned long x)
+{
+	/* The implementation here tailored to a particular
+	 * setting of USER_HZ.
+	 */
+	u64 tick_nsec = (NSEC_PER_SEC + CONFIG_HZ/2) / CONFIG_HZ;
+	u64 user_hz_nsec = NSEC_PER_SEC / USER_HZ;
+
+	if ((tick_nsec % user_hz_nsec) == 0) {
+		if (CONFIG_HZ < USER_HZ)
+			return x * (USER_HZ / CONFIG_HZ);
+		else
+			return x / (CONFIG_HZ / USER_HZ);
+	}
+	return x * tick_nsec/user_hz_nsec;
+}
+
+static clock_t jiffies_delta_to_clock_t(long delta)
+{
+	if (delta <= 0)
+		return 0;
+
+	return jiffies_to_clock_t(delta);
+}
+
+static long sock_i_ino(const struct sock *sk)
+{
+	const struct socket *sk_socket = sk->sk_socket;
+	const struct inode *inode;
+	unsigned long ino;
+
+	if (!sk_socket)
+		return 0;
+
+	inode = &container_of(sk_socket, struct socket_alloc, socket)->vfs_inode;
+	bpf_probe_read(&ino, sizeof(ino), &inode->i_ino);
+	return ino;
+}
+
+static bool
+inet_csk_in_pingpong_mode(const struct inet_connection_sock *icsk)
+{
+	return icsk->icsk_ack.pingpong >= TCP_PINGPONG_THRESH;
+}
+
+static bool tcp_in_initial_slowstart(const struct tcp_sock *tcp)
+{
+	return tcp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
+}
+
+static int dump_tcp_sock(struct seq_file *seq, struct tcp_sock *tp,
+			 uid_t uid, __u32 seq_num)
+{
+	const struct inet_connection_sock *icsk;
+	const struct fastopen_queue *fastopenq;
+	const struct inet_sock *inet;
+	unsigned long timer_expires;
+	const struct sock *sp;
+	__u16 destp, srcp;
+	__be32 dest, src;
+	int timer_active;
+	int rx_queue;
+	int state;
+
+	icsk = &tp->inet_conn;
+	inet = &icsk->icsk_inet;
+	sp = &inet->sk;
+	fastopenq = &icsk->icsk_accept_queue.fastopenq;
+
+	dest = inet->inet_daddr;
+	src = inet->inet_rcv_saddr;
+	destp = bpf_ntohs(inet->inet_dport);
+	srcp = bpf_ntohs(inet->inet_sport);
+
+	if (icsk->icsk_pending == ICSK_TIME_RETRANS ||
+	    icsk->icsk_pending == ICSK_TIME_REO_TIMEOUT ||
+	    icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) {
+		timer_active = 1;
+		timer_expires = icsk->icsk_timeout;
+	} else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
+		timer_active = 4;
+		timer_expires = icsk->icsk_timeout;
+	} else if (timer_pending(&sp->sk_timer)) {
+		timer_active = 2;
+		timer_expires = sp->sk_timer.expires;
+	} else {
+		timer_active = 0;
+		timer_expires = bpf_jiffies64();
+	}
+
+	state = sp->sk_state;
+	if (state == TCP_LISTEN) {
+		rx_queue = sp->sk_ack_backlog;
+	} else {
+		rx_queue = tp->rcv_nxt - tp->copied_seq;
+		if (rx_queue < 0)
+			rx_queue = 0;
+	}
+
+	BPF_SEQ_PRINTF(seq, "%4d: %08X:%04X %08X:%04X ",
+		       seq_num, src, srcp, destp, destp);
+	BPF_SEQ_PRINTF(seq, "%02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d ",
+		       state,
+		       tp->write_seq - tp->snd_una, rx_queue,
+		       timer_active,
+		       jiffies_delta_to_clock_t(timer_expires - bpf_jiffies64()),
+		       icsk->icsk_retransmits, uid,
+		       icsk->icsk_probes_out,
+		       sock_i_ino(sp),
+		       sp->sk_refcnt.refs.counter);
+	BPF_SEQ_PRINTF(seq, "%pK %lu %lu %u %u %d\n",
+		       tp,
+		       jiffies_to_clock_t(icsk->icsk_rto),
+		       jiffies_to_clock_t(icsk->icsk_ack.ato),
+		       (icsk->icsk_ack.quick << 1) | inet_csk_in_pingpong_mode(icsk),
+		       tp->snd_cwnd,
+		       state == TCP_LISTEN ? fastopenq->max_qlen
+				: (tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh)
+		      );
+
+	return 0;
+}
+
+static int dump_tw_sock(struct seq_file *seq, struct tcp_timewait_sock *ttw,
+			uid_t uid, __u32 seq_num)
+{
+	struct inet_timewait_sock *tw = &ttw->tw_sk;
+	__u16 destp, srcp;
+	__be32 dest, src;
+	long delta;
+
+	delta = tw->tw_timer.expires - bpf_jiffies64();
+	dest = tw->tw_daddr;
+	src  = tw->tw_rcv_saddr;
+	destp = bpf_ntohs(tw->tw_dport);
+	srcp  = bpf_ntohs(tw->tw_sport);
+
+	BPF_SEQ_PRINTF(seq, "%4d: %08X:%04X %08X:%04X ",
+		       seq_num, src, srcp, dest, destp);
+
+	BPF_SEQ_PRINTF(seq, "%02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK\n",
+		       tw->tw_substate, 0, 0,
+		       3, jiffies_delta_to_clock_t(delta), 0, 0, 0, 0,
+		       tw->tw_refcnt.refs.counter, tw);
+
+	return 0;
+}
+
+static int dump_req_sock(struct seq_file *seq, struct tcp_request_sock *treq,
+			 uid_t uid, __u32 seq_num)
+{
+	struct inet_request_sock *irsk = &treq->req;
+	struct request_sock *req = &irsk->req;
+	long ttd;
+
+	ttd = req->rsk_timer.expires - bpf_jiffies64();
+
+	if (ttd < 0)
+		ttd = 0;
+
+	BPF_SEQ_PRINTF(seq, "%4d: %08X:%04X %08X:%04X ",
+		       seq_num, irsk->ir_loc_addr,
+		       irsk->ir_num, irsk->ir_rmt_addr,
+		       bpf_ntohs(irsk->ir_rmt_port));
+	BPF_SEQ_PRINTF(seq, "%02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK\n",
+		       TCP_SYN_RECV, 0, 0, 1, jiffies_to_clock_t(ttd),
+		       req->num_timeout, uid, 0, 0, 0, req);
+
+	return 0;
+}
+
+SEC("iter/tcp")
+int dump_tcp4(struct bpf_iter__tcp *ctx)
+{
+	struct sock_common *sk_common = ctx->sk_common;
+	struct seq_file *seq = ctx->meta->seq;
+	struct tcp_timewait_sock *tw;
+	struct tcp_request_sock *req;
+	struct tcp_sock *tp;
+	uid_t uid = ctx->uid;
+	__u32 seq_num;
+
+	if (sk_common == (void *)0)
+		return 0;
+
+	seq_num = ctx->meta->seq_num;
+	if (seq_num == 0)
+		BPF_SEQ_PRINTF(seq, "  sl  "
+				    "local_address "
+				    "rem_address   "
+				    "st tx_queue rx_queue tr tm->when retrnsmt"
+				    "   uid  timeout inode\n");
+
+	if (sk_common->skc_family != AF_INET)
+		return 0;
+
+	tp = bpf_skc_to_tcp_sock(sk_common);
+	if (tp)
+		return dump_tcp_sock(seq, tp, uid, seq_num);
+
+	tw = bpf_skc_to_tcp_timewait_sock(sk_common);
+	if (tw)
+		return dump_tw_sock(seq, tw, uid, seq_num);
+
+	req = bpf_skc_to_tcp_request_sock(sk_common);
+	if (req)
+		return dump_req_sock(seq, req, uid, seq_num);
+
+	return 0;
+}