[PATCH v7 bpf-next 00/10] bpf: Add socket destroy capability

[PATCH v7 bpf-next 00/10] bpf: Add socket destroy capability

[Aditi Ghag]

This patch adds the capability to destroy sockets in BPF. We plan to use
the capability in Cilium to force client sockets to reconnect when their
remote load-balancing backends are deleted. The other use case is
on-the-fly policy enforcement where existing socket connections prevented
by policies need to be terminated.

The use cases, and more details around
the selected approach were presented at LPC 2022 -
https://lpc.events/event/16/contributions/1358/.
RFC discussion -
https://lore.kernel.org/netdev/CABG=zsBEh-P4NXk23eBJw7eajB5YJeRS7oPXnTAzs=yob4EMoQ@mail.gmail.com/T/#u.
v6 patch series -
https://lore.kernel.org/bpf/20230418153148.2231644-1-aditi.ghag@isovalent.com/

v7 highlights:
Address review comments:
Martin:
- Refactored logic to get udp table to a separate commit.
- Addressed nits in the batching and test commits.
- Applied patch to filter and restrict the kfunc, and added a test.
Stan:
- Addressed nits in the network helper commit.
Paolo/Yonghong:
- Extended the first commit that revises locking in BPF TCP iterator
  with more details.
- Fixed comment formatting.

(Below notes are same as v6 patch series that are still relevant. Refer to
earlier patch series for other notes.)
- I hit a snag while writing the kfunc where verifier complained about the
  `sock_common` type passed from TCP iterator. With kfuncs, there don't
  seem to be any options available to pass BTF type hints to the verifier
  (equivalent of `ARG_PTR_TO_BTF_ID_SOCK_COMMON`, as was the case with the
  helper).  As a result, I changed the argument type of the sock_destory
  kfunc to `sock_common`.

Aditi Ghag (10):
  bpf: tcp: Avoid taking fast sock lock in iterator
  udp: seq_file: Helper function to match socket attributes
  bpf: udp: Encapsulate logic to get udp table
  udp: seq_file: Remove bpf_seq_afinfo from udp_iter_state
  bpf: udp: Implement batching for sockets iterator
  bpf: Add bpf_sock_destroy kfunc
  selftests/bpf: Add helper to get port using getsockname
  selftests/bpf: Test bpf_sock_destroy
  bpf: Add a kfunc filter function to 'struct btf_kfunc_id_set'
  selftests/bpf: Extend bpf_sock_destroy tests

 include/linux/btf.h                           |  18 +-
 include/net/udp.h                             |   1 -
 kernel/bpf/btf.c                              |  59 +++-
 kernel/bpf/verifier.c                         |   7 +-
 net/core/filter.c                             |  66 ++++
 net/ipv4/tcp.c                                |  10 +-
 net/ipv4/tcp_ipv4.c                           |   5 +-
 net/ipv4/udp.c                                | 287 +++++++++++++++---
 tools/testing/selftests/bpf/network_helpers.c |  23 ++
 tools/testing/selftests/bpf/network_helpers.h |   1 +
 .../selftests/bpf/prog_tests/sock_destroy.c   | 217 +++++++++++++
 .../selftests/bpf/progs/sock_destroy_prog.c   | 145 +++++++++
 .../bpf/progs/sock_destroy_prog_fail.c        |  22 ++
 13 files changed, 785 insertions(+), 76 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/sock_destroy.c
 create mode 100644 tools/testing/selftests/bpf/progs/sock_destroy_prog.c
 create mode 100644 tools/testing/selftests/bpf/progs/sock_destroy_prog_fail.c

-- 
2.34.1

[PATCH v7 bpf-next 01/10] bpf: tcp: Avoid taking fast sock lock in iterator

[Aditi Ghag]

Previously, BPF TCP iterator was acquiring fast version of sock lock that
disables the BH. This introduced a circular dependency with code paths that
later acquire sockets hash table bucket lock.
Replace the fast version of sock lock with slow that faciliates BPF
programs executed from the iterator to destroy TCP listening sockets
using the bpf_sock_destroy kfunc (implemened in follow-up commits).

Here is a stack trace that motivated this change:

```
lock_acquire+0xcd/0x330
_raw_spin_lock+0x33/0x40
------> sock lock acquired with BH enabled
sk_clone_lock+0x146/0x520
inet_csk_clone_lock+0x1b/0x110
tcp_create_openreq_child+0x22/0x3f0
tcp_v6_syn_recv_sock+0x96/0x940


lock_acquire+0xcd/0x330
_raw_spin_lock+0x33/0x40
------> Acquire (bucket) lhash2.lock (may cause deadlock if interrupted)
__inet_hash+0x4b/0x210
inet_csk_listen_start+0xe6/0x100
inet_listen+0x95/0x1d0
__sys_listen+0x69/0xb0
__x64_sys_listen+0x14/0x20
do_syscall_64+0x3c/0x90
entry_SYSCALL_64_after_hwframe+0x72/0xdc


lock_acquire+0xcd/0x330
_raw_spin_lock+0x33/0x40
------> Acquire (bucket) lhash2.lock
inet_unhash+0x9a/0x110
tcp_set_state+0x6a/0x210
tcp_abort+0x10d/0x200
bpf_prog_6793c5ca50c43c0d_iter_tcp6_server+0xa4/0xa9
bpf_iter_run_prog+0x1ff/0x340
------> Release (bucket) lhash2.lock
bpf_iter_tcp_seq_show+0xca/0x190
------> Acquire (bucket) lhash2.lock
------> sock lock acquired with BH disabled
bpf_seq_read+0x177/0x450

```

Acked-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Aditi Ghag <aditi.ghag@isovalent.com>
---
 net/ipv4/tcp_ipv4.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index ea370afa70ed..f2d370a9450f 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2962,7 +2962,6 @@ 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;
-	bool slow;
 	uid_t uid;
 	int ret;
 
@@ -2970,7 +2969,7 @@ static int bpf_iter_tcp_seq_show(struct seq_file *seq, void *v)
 		return 0;
 
 	if (sk_fullsock(sk))
-		slow = lock_sock_fast(sk);
+		lock_sock(sk);
 
 	if (unlikely(sk_unhashed(sk))) {
 		ret = SEQ_SKIP;
@@ -2994,7 +2993,7 @@ static int bpf_iter_tcp_seq_show(struct seq_file *seq, void *v)
 
 unlock:
 	if (sk_fullsock(sk))
-		unlock_sock_fast(sk, slow);
+		release_sock(sk);
 	return ret;
 
 }
-- 
2.34.1

[PATCH v7 bpf-next 02/10] udp: seq_file: Helper function to match socket attributes

[Aditi Ghag]

This is a preparatory commit to refactor code that matches socket
attributes in iterators to a helper function, and use it in the
proc fs iterator.

Signed-off-by: Aditi Ghag <aditi.ghag@isovalent.com>
---
 net/ipv4/udp.c | 34 +++++++++++++++++++++++++++-------
 1 file changed, 27 insertions(+), 7 deletions(-)

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index c605d171eb2d..71e3fef44fd5 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2983,6 +2983,16 @@ EXPORT_SYMBOL(udp_prot);
 /* ------------------------------------------------------------------------ */
 #ifdef CONFIG_PROC_FS
 
+static unsigned short seq_file_family(const struct seq_file *seq);
+static bool seq_sk_match(struct seq_file *seq, const struct sock *sk)
+{
+	unsigned short family = seq_file_family(seq);
+
+	/* AF_UNSPEC is used as a match all */
+	return ((family == AF_UNSPEC || family == sk->sk_family) &&
+		net_eq(sock_net(sk), seq_file_net(seq)));
+}
+
 static struct udp_table *udp_get_table_afinfo(struct udp_seq_afinfo *afinfo,
 					      struct net *net)
 {
@@ -3013,10 +3023,7 @@ static struct sock *udp_get_first(struct seq_file *seq, int start)
 
 		spin_lock_bh(&hslot->lock);
 		sk_for_each(sk, &hslot->head) {
-			if (!net_eq(sock_net(sk), net))
-				continue;
-			if (afinfo->family == AF_UNSPEC ||
-			    sk->sk_family == afinfo->family)
+			if (seq_sk_match(seq, sk))
 				goto found;
 		}
 		spin_unlock_bh(&hslot->lock);
@@ -3040,9 +3047,7 @@ static struct sock *udp_get_next(struct seq_file *seq, struct sock *sk)
 
 	do {
 		sk = sk_next(sk);
-	} while (sk && (!net_eq(sock_net(sk), net) ||
-			(afinfo->family != AF_UNSPEC &&
-			 sk->sk_family != afinfo->family)));
+	} while (sk && !seq_sk_match(seq, sk));
 
 	if (!sk) {
 		udptable = udp_get_table_afinfo(afinfo, net);
@@ -3205,6 +3210,21 @@ static const struct seq_operations bpf_iter_udp_seq_ops = {
 };
 #endif
 
+static unsigned short seq_file_family(const struct seq_file *seq)
+{
+	const struct udp_seq_afinfo *afinfo;
+
+#ifdef CONFIG_BPF_SYSCALL
+	/* BPF iterator: bpf programs to filter sockets. */
+	if (seq->op == &bpf_iter_udp_seq_ops)
+		return AF_UNSPEC;
+#endif
+
+	/* Proc fs iterator */
+	afinfo = pde_data(file_inode(seq->file));
+	return afinfo->family;
+}
+
 const struct seq_operations udp_seq_ops = {
 	.start		= udp_seq_start,
 	.next		= udp_seq_next,
-- 
2.34.1

[PATCH v7 bpf-next 03/10] bpf: udp: Encapsulate logic to get udp table

[Aditi Ghag]

This is a preparatory commit that encapsulates the logic
to get udp table in iterator inside udp_get_table_afinfo, and
renames the function to udp_get_table_seq accordingly.

Suggested-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Aditi Ghag <aditi.ghag@isovalent.com>
---
 net/ipv4/udp.c | 35 ++++++++++++-----------------------
 1 file changed, 12 insertions(+), 23 deletions(-)

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 71e3fef44fd5..c426ebafeb13 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2993,9 +2993,16 @@ static bool seq_sk_match(struct seq_file *seq, const struct sock *sk)
 		net_eq(sock_net(sk), seq_file_net(seq)));
 }
 
-static struct udp_table *udp_get_table_afinfo(struct udp_seq_afinfo *afinfo,
-					      struct net *net)
+static struct udp_table *udp_get_table_seq(struct seq_file *seq,
+					   struct net *net)
 {
+	const struct udp_iter_state *state = seq->private;
+	const struct udp_seq_afinfo *afinfo;
+
+	if (state->bpf_seq_afinfo)
+		return net->ipv4.udp_table;
+
+	afinfo = pde_data(file_inode(seq->file));
 	return afinfo->udp_table ? : net->ipv4.udp_table;
 }
 
@@ -3003,16 +3010,10 @@ static struct sock *udp_get_first(struct seq_file *seq, int start)
 {
 	struct udp_iter_state *state = seq->private;
 	struct net *net = seq_file_net(seq);
-	struct udp_seq_afinfo *afinfo;
 	struct udp_table *udptable;
 	struct sock *sk;
 
-	if (state->bpf_seq_afinfo)
-		afinfo = state->bpf_seq_afinfo;
-	else
-		afinfo = pde_data(file_inode(seq->file));
-
-	udptable = udp_get_table_afinfo(afinfo, net);
+	udptable = udp_get_table_seq(seq, net);
 
 	for (state->bucket = start; state->bucket <= udptable->mask;
 	     ++state->bucket) {
@@ -3037,20 +3038,14 @@ static struct sock *udp_get_next(struct seq_file *seq, struct sock *sk)
 {
 	struct udp_iter_state *state = seq->private;
 	struct net *net = seq_file_net(seq);
-	struct udp_seq_afinfo *afinfo;
 	struct udp_table *udptable;
 
-	if (state->bpf_seq_afinfo)
-		afinfo = state->bpf_seq_afinfo;
-	else
-		afinfo = pde_data(file_inode(seq->file));
-
 	do {
 		sk = sk_next(sk);
 	} while (sk && !seq_sk_match(seq, sk));
 
 	if (!sk) {
-		udptable = udp_get_table_afinfo(afinfo, net);
+		udptable = udp_get_table_seq(seq, net);
 
 		if (state->bucket <= udptable->mask)
 			spin_unlock_bh(&udptable->hash[state->bucket].lock);
@@ -3096,15 +3091,9 @@ EXPORT_SYMBOL(udp_seq_next);
 void udp_seq_stop(struct seq_file *seq, void *v)
 {
 	struct udp_iter_state *state = seq->private;
-	struct udp_seq_afinfo *afinfo;
 	struct udp_table *udptable;
 
-	if (state->bpf_seq_afinfo)
-		afinfo = state->bpf_seq_afinfo;
-	else
-		afinfo = pde_data(file_inode(seq->file));
-
-	udptable = udp_get_table_afinfo(afinfo, seq_file_net(seq));
+	udptable = udp_get_table_seq(seq, seq_file_net(seq));
 
 	if (state->bucket <= udptable->mask)
 		spin_unlock_bh(&udptable->hash[state->bucket].lock);
-- 
2.34.1

[PATCH v7 bpf-next 04/10] udp: seq_file: Remove bpf_seq_afinfo from udp_iter_state

[Aditi Ghag]

This is a preparatory commit to remove the field. The field was
previously shared between proc fs and BPF UDP socket iterators. As the
follow-up commits will decouple the implementation for the iterators,
remove the field. As for BPF socket iterator, filtering of sockets is
exepected to be done in BPF programs.

Suggested-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Aditi Ghag <aditi.ghag@isovalent.com>
---
 include/net/udp.h |  1 -
 net/ipv4/udp.c    | 25 +++++--------------------
 2 files changed, 5 insertions(+), 21 deletions(-)

diff --git a/include/net/udp.h b/include/net/udp.h
index de4b528522bb..5cad44318d71 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -437,7 +437,6 @@ struct udp_seq_afinfo {
 struct udp_iter_state {
 	struct seq_net_private  p;
 	int			bucket;
-	struct udp_seq_afinfo	*bpf_seq_afinfo;
 };
 
 void *udp_seq_start(struct seq_file *seq, loff_t *pos);
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index c426ebafeb13..9f8c1554a9e4 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2993,14 +2993,16 @@ static bool seq_sk_match(struct seq_file *seq, const struct sock *sk)
 		net_eq(sock_net(sk), seq_file_net(seq)));
 }
 
+static const struct seq_operations bpf_iter_udp_seq_ops;
 static struct udp_table *udp_get_table_seq(struct seq_file *seq,
 					   struct net *net)
 {
-	const struct udp_iter_state *state = seq->private;
 	const struct udp_seq_afinfo *afinfo;
 
-	if (state->bpf_seq_afinfo)
+#ifdef CONFIG_BPF_SYSCALL
+	if (seq->op == &bpf_iter_udp_seq_ops)
 		return net->ipv4.udp_table;
+#endif
 
 	afinfo = pde_data(file_inode(seq->file));
 	return afinfo->udp_table ? : net->ipv4.udp_table;
@@ -3424,28 +3426,11 @@ DEFINE_BPF_ITER_FUNC(udp, struct bpf_iter_meta *meta,
 
 static int bpf_iter_init_udp(void *priv_data, struct bpf_iter_aux_info *aux)
 {
-	struct udp_iter_state *st = priv_data;
-	struct udp_seq_afinfo *afinfo;
-	int ret;
-
-	afinfo = kmalloc(sizeof(*afinfo), GFP_USER | __GFP_NOWARN);
-	if (!afinfo)
-		return -ENOMEM;
-
-	afinfo->family = AF_UNSPEC;
-	afinfo->udp_table = NULL;
-	st->bpf_seq_afinfo = afinfo;
-	ret = bpf_iter_init_seq_net(priv_data, aux);
-	if (ret)
-		kfree(afinfo);
-	return ret;
+	return bpf_iter_init_seq_net(priv_data, aux);
 }
 
 static void bpf_iter_fini_udp(void *priv_data)
 {
-	struct udp_iter_state *st = priv_data;
-
-	kfree(st->bpf_seq_afinfo);
 	bpf_iter_fini_seq_net(priv_data);
 }
 
-- 
2.34.1

[PATCH v7 bpf-next 05/10] bpf: udp: Implement batching for sockets iterator

[Aditi Ghag]

Batch UDP sockets from BPF iterator that allows for overlapping locking
semantics in BPF/kernel helpers executed in BPF programs.  This facilitates
BPF socket destroy kfunc (introduced by follow-up patches) to execute from
BPF iterator programs.

Previously, BPF iterators acquired the sock lock and sockets hash table
bucket lock while executing BPF programs. This prevented BPF helpers that
again acquire these locks to be executed from BPF iterators.  With the
batching approach, we acquire a bucket lock, batch all the bucket sockets,
and then release the bucket lock. This enables BPF or kernel helpers to
skip sock locking when invoked in the supported BPF contexts.

The batching logic is similar to the logic implemented in TCP iterator:
https://lore.kernel.org/bpf/20210701200613.1036157-1-kafai@fb.com/.

Suggested-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Aditi Ghag <aditi.ghag@isovalent.com>
---
 net/ipv4/udp.c | 205 +++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 199 insertions(+), 6 deletions(-)

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 9f8c1554a9e4..150551acab9d 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -3148,6 +3148,143 @@ struct bpf_iter__udp {
 	int bucket __aligned(8);
 };
 
+struct bpf_udp_iter_state {
+	struct udp_iter_state state;
+	unsigned int cur_sk;
+	unsigned int end_sk;
+	unsigned int max_sk;
+	int offset;
+	struct sock **batch;
+	bool st_bucket_done;
+};
+
+static int bpf_iter_udp_realloc_batch(struct bpf_udp_iter_state *iter,
+				      unsigned int new_batch_sz);
+static struct sock *bpf_iter_udp_batch(struct seq_file *seq)
+{
+	struct bpf_udp_iter_state *iter = seq->private;
+	struct udp_iter_state *state = &iter->state;
+	struct net *net = seq_file_net(seq);
+	struct udp_table *udptable;
+	unsigned int batch_sks = 0;
+	bool resized = false;
+	struct sock *sk;
+
+	/* The current batch is done, so advance the bucket. */
+	if (iter->st_bucket_done) {
+		state->bucket++;
+		iter->offset = 0;
+	}
+
+	udptable = udp_get_table_seq(seq, net);
+
+again:
+	/* New batch for the next bucket.
+	 * Iterate over the hash table to find a bucket with sockets matching
+	 * the iterator attributes, and return the first matching socket from
+	 * the bucket. The remaining matched sockets from the bucket are batched
+	 * before releasing the bucket lock. This allows BPF programs that are
+	 * called in seq_show to acquire the bucket lock if needed.
+	 */
+	iter->cur_sk = 0;
+	iter->end_sk = 0;
+	iter->st_bucket_done = false;
+	batch_sks = 0;
+
+	for (; state->bucket <= udptable->mask; state->bucket++) {
+		struct udp_hslot *hslot2 = &udptable->hash2[state->bucket];
+
+		if (hlist_empty(&hslot2->head)) {
+			iter->offset = 0;
+			continue;
+		}
+
+		spin_lock_bh(&hslot2->lock);
+		udp_portaddr_for_each_entry(sk, &hslot2->head) {
+			if (seq_sk_match(seq, sk)) {
+				/* Resume from the last iterated socket at the
+				 * offset in the bucket before iterator was stopped.
+				 */
+				if (iter->offset) {
+					--iter->offset;
+					continue;
+				}
+				if (iter->end_sk < iter->max_sk) {
+					sock_hold(sk);
+					iter->batch[iter->end_sk++] = sk;
+				}
+				batch_sks++;
+			}
+		}
+		spin_unlock_bh(&hslot2->lock);
+
+		if (iter->end_sk)
+			break;
+
+		/* Reset the current bucket's offset before moving to the next bucket. */
+		iter->offset = 0;
+	}
+
+	/* All done: no batch made. */
+	if (!iter->end_sk)
+		return NULL;
+
+	if (iter->end_sk == batch_sks) {
+		/* Batching is done for the current bucket; return the first
+		 * socket to be iterated from the batch.
+		 */
+		iter->st_bucket_done = true;
+		goto done;
+	}
+	if (!resized && !bpf_iter_udp_realloc_batch(iter, batch_sks * 3 / 2)) {
+		resized = true;
+		/* After allocating a larger batch, retry one more time to grab
+		 * the whole bucket.
+		 */
+		state->bucket--;
+		goto again;
+	}
+done:
+	return iter->batch[0];
+}
+
+static void *bpf_iter_udp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	struct bpf_udp_iter_state *iter = seq->private;
+	struct sock *sk;
+
+	/* Whenever seq_next() is called, the iter->cur_sk is
+	 * done with seq_show(), so unref the iter->cur_sk.
+	 */
+	if (iter->cur_sk < iter->end_sk) {
+		sock_put(iter->batch[iter->cur_sk++]);
+		++iter->offset;
+	}
+
+	/* After updating iter->cur_sk, check if there are more sockets
+	 * available in the current bucket batch.
+	 */
+	if (iter->cur_sk < iter->end_sk)
+		sk = iter->batch[iter->cur_sk];
+	else
+		/* Prepare a new batch. */
+		sk = bpf_iter_udp_batch(seq);
+
+	++*pos;
+	return sk;
+}
+
+static void *bpf_iter_udp_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	/* bpf iter does not support lseek, so it always
+	 * continue from where it was stop()-ped.
+	 */
+	if (*pos)
+		return bpf_iter_udp_batch(seq);
+
+	return SEQ_START_TOKEN;
+}
+
 static int udp_prog_seq_show(struct bpf_prog *prog, struct bpf_iter_meta *meta,
 			     struct udp_sock *udp_sk, uid_t uid, int bucket)
 {
@@ -3168,18 +3305,37 @@ static int bpf_iter_udp_seq_show(struct seq_file *seq, void *v)
 	struct bpf_prog *prog;
 	struct sock *sk = v;
 	uid_t uid;
+	int ret;
 
 	if (v == SEQ_START_TOKEN)
 		return 0;
 
+	lock_sock(sk);
+
+	if (unlikely(sk_unhashed(sk))) {
+		ret = SEQ_SKIP;
+		goto unlock;
+	}
+
 	uid = from_kuid_munged(seq_user_ns(seq), sock_i_uid(sk));
 	meta.seq = seq;
 	prog = bpf_iter_get_info(&meta, false);
-	return udp_prog_seq_show(prog, &meta, v, uid, state->bucket);
+	ret = udp_prog_seq_show(prog, &meta, v, uid, state->bucket);
+
+unlock:
+	release_sock(sk);
+	return ret;
+}
+
+static void bpf_iter_udp_put_batch(struct bpf_udp_iter_state *iter)
+{
+	while (iter->cur_sk < iter->end_sk)
+		sock_put(iter->batch[iter->cur_sk++]);
 }
 
 static void bpf_iter_udp_seq_stop(struct seq_file *seq, void *v)
 {
+	struct bpf_udp_iter_state *iter = seq->private;
 	struct bpf_iter_meta meta;
 	struct bpf_prog *prog;
 
@@ -3190,12 +3346,15 @@ static void bpf_iter_udp_seq_stop(struct seq_file *seq, void *v)
 			(void)udp_prog_seq_show(prog, &meta, v, 0, 0);
 	}
 
-	udp_seq_stop(seq, v);
+	if (iter->cur_sk < iter->end_sk) {
+		bpf_iter_udp_put_batch(iter);
+		iter->st_bucket_done = false;
+	}
 }
 
 static const struct seq_operations bpf_iter_udp_seq_ops = {
-	.start		= udp_seq_start,
-	.next		= udp_seq_next,
+	.start		= bpf_iter_udp_seq_start,
+	.next		= bpf_iter_udp_seq_next,
 	.stop		= bpf_iter_udp_seq_stop,
 	.show		= bpf_iter_udp_seq_show,
 };
@@ -3424,21 +3583,55 @@ static struct pernet_operations __net_initdata udp_sysctl_ops = {
 DEFINE_BPF_ITER_FUNC(udp, struct bpf_iter_meta *meta,
 		     struct udp_sock *udp_sk, uid_t uid, int bucket)
 
+static int bpf_iter_udp_realloc_batch(struct bpf_udp_iter_state *iter,
+				      unsigned int new_batch_sz)
+{
+	struct sock **new_batch;
+
+	new_batch = kvmalloc_array(new_batch_sz, sizeof(*new_batch),
+				   GFP_USER | __GFP_NOWARN);
+	if (!new_batch)
+		return -ENOMEM;
+
+	bpf_iter_udp_put_batch(iter);
+	kvfree(iter->batch);
+	iter->batch = new_batch;
+	iter->max_sk = new_batch_sz;
+
+	return 0;
+}
+
+#define INIT_BATCH_SZ 16
+
 static int bpf_iter_init_udp(void *priv_data, struct bpf_iter_aux_info *aux)
 {
-	return bpf_iter_init_seq_net(priv_data, aux);
+	struct bpf_udp_iter_state *iter = priv_data;
+	int ret;
+
+	ret = bpf_iter_init_seq_net(priv_data, aux);
+	if (ret)
+		return ret;
+
+	ret = bpf_iter_udp_realloc_batch(iter, INIT_BATCH_SZ);
+	if (ret)
+		bpf_iter_fini_seq_net(priv_data);
+
+	return ret;
 }
 
 static void bpf_iter_fini_udp(void *priv_data)
 {
+	struct bpf_udp_iter_state *iter = priv_data;
+
 	bpf_iter_fini_seq_net(priv_data);
+	kvfree(iter->batch);
 }
 
 static const struct bpf_iter_seq_info udp_seq_info = {
 	.seq_ops		= &bpf_iter_udp_seq_ops,
 	.init_seq_private	= bpf_iter_init_udp,
 	.fini_seq_private	= bpf_iter_fini_udp,
-	.seq_priv_size		= sizeof(struct udp_iter_state),
+	.seq_priv_size		= sizeof(struct bpf_udp_iter_state),
 };
 
 static struct bpf_iter_reg udp_reg_info = {
-- 
2.34.1

[PATCH v7 bpf-next 06/10] bpf: Add bpf_sock_destroy kfunc

[Aditi Ghag]

The socket destroy kfunc is used to forcefully terminate sockets from
certain BPF contexts. We plan to use the capability in Cilium to force
client sockets to reconnect when their remote load-balancing backends are
deleted. The other use case is on-the-fly policy enforcement where existing
socket connections prevented by policies need to be forcefully terminated.
The helper allows terminating sockets that may or may not be actively
sending traffic.

The helper is currently exposed to certain BPF iterators where users can
filter, and terminate selected sockets. Additionally, the helper can only
be called from these BPF contexts that ensure socket locking in order to
allow synchronous execution of destroy helpers that also acquire socket
locks. The previous commit that batches UDP sockets during iteration
facilitated a synchronous invocation of the destroy helper from BPF context
by skipping taking socket locks in the destroy handler. TCP iterators
already supported batching.
Follow-up commits will ensure that the kfunc can only be called from
programs with `BPF_TRACE_ITER` attach type.

The helper takes `sock_common` type argument, even though it expects, and
casts them to a `sock` pointer. This enables the verifier to allow the
sock_destroy kfunc to be called for TCP with `sock_common` and UDP with
`sock` structs. As a comparison, BPF helpers enable this behavior with the
`ARG_PTR_TO_BTF_ID_SOCK_COMMON` argument type. However, there is no such
option available with the verifier logic that handles kfuncs where BTF
types are inferred. Furthermore, as `sock_common` only has a subset of
certain fields of `sock`, casting pointer to the latter type might not
always be safe for certain sockets like request sockets, but these have
a special handling in the diag_destroy handlers.

Signed-off-by: Aditi Ghag <aditi.ghag@isovalent.com>
---
 net/core/filter.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++
 net/ipv4/tcp.c    | 10 ++++++---
 net/ipv4/udp.c    |  6 +++--
 3 files changed, 68 insertions(+), 5 deletions(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index 727c5269867d..97d70b7959a1 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -11715,3 +11715,60 @@ static int __init bpf_kfunc_init(void)
 	return ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &bpf_kfunc_set_xdp);
 }
 late_initcall(bpf_kfunc_init);
+
+/* Disables missing prototype warnings */
+__diag_push();
+__diag_ignore_all("-Wmissing-prototypes",
+		  "Global functions as their definitions will be in vmlinux BTF");
+
+/* bpf_sock_destroy: Destroy the given socket with ECONNABORTED error code.
+ *
+ * The function expects a non-NULL pointer to a socket, and invokes the
+ * protocol specific socket destroy handlers.
+ *
+ * The helper can only be called from BPF contexts that have acquired the socket
+ * locks.
+ *
+ * Parameters:
+ * @sock: Pointer to socket to be destroyed
+ *
+ * Return:
+ * On error, may return EPROTONOSUPPORT, EINVAL.
+ * EPROTONOSUPPORT if protocol specific destroy handler is not supported.
+ * 0 otherwise
+ */
+__bpf_kfunc int bpf_sock_destroy(struct sock_common *sock)
+{
+	struct sock *sk = (struct sock *)sock;
+
+	if (!sk)
+		return -EINVAL;
+
+	/* The locking semantics that allow for synchronous execution of the
+	 * destroy handlers are only supported for TCP and UDP.
+	 * Supporting protocols will need to acquire lock_sock in the BPF context
+	 * prior to invoking this kfunc.
+	 */
+	if (!sk->sk_prot->diag_destroy || (sk->sk_protocol != IPPROTO_TCP &&
+					   sk->sk_protocol != IPPROTO_UDP))
+		return -EOPNOTSUPP;
+
+	return sk->sk_prot->diag_destroy(sk, ECONNABORTED);
+}
+
+__diag_pop()
+
+BTF_SET8_START(sock_destroy_kfunc_set)
+BTF_ID_FLAGS(func, bpf_sock_destroy)
+BTF_SET8_END(sock_destroy_kfunc_set)
+
+static const struct btf_kfunc_id_set bpf_sock_destroy_kfunc_set = {
+	.owner = THIS_MODULE,
+	.set   = &sock_destroy_kfunc_set,
+};
+
+static int init_subsystem(void)
+{
+	return register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &bpf_sock_destroy_kfunc_set);
+}
+late_initcall(init_subsystem);
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 288693981b00..2259b4facc2f 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -4679,8 +4679,10 @@ int tcp_abort(struct sock *sk, int err)
 		return 0;
 	}
 
-	/* Don't race with userspace socket closes such as tcp_close. */
-	lock_sock(sk);
+	/* BPF context ensures sock locking. */
+	if (!has_current_bpf_ctx())
+		/* Don't race with userspace socket closes such as tcp_close. */
+		lock_sock(sk);
 
 	if (sk->sk_state == TCP_LISTEN) {
 		tcp_set_state(sk, TCP_CLOSE);
@@ -4702,9 +4704,11 @@ int tcp_abort(struct sock *sk, int err)
 	}
 
 	bh_unlock_sock(sk);
+
 	local_bh_enable();
 	tcp_write_queue_purge(sk);
-	release_sock(sk);
+	if (!has_current_bpf_ctx())
+		release_sock(sk);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(tcp_abort);
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 150551acab9d..5f48cdf82a45 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2925,7 +2925,8 @@ EXPORT_SYMBOL(udp_poll);
 
 int udp_abort(struct sock *sk, int err)
 {
-	lock_sock(sk);
+	if (!has_current_bpf_ctx())
+		lock_sock(sk);
 
 	/* udp{v6}_destroy_sock() sets it under the sk lock, avoid racing
 	 * with close()
@@ -2938,7 +2939,8 @@ int udp_abort(struct sock *sk, int err)
 	__udp_disconnect(sk, 0);
 
 out:
-	release_sock(sk);
+	if (!has_current_bpf_ctx())
+		release_sock(sk);
 
 	return 0;
 }
-- 
2.34.1

[PATCH v7 bpf-next 07/10] selftests/bpf: Add helper to get port using getsockname

[Aditi Ghag]

The helper will be used to programmatically retrieve,
and pass ports in userspace and kernel selftest programs.

Suggested-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Aditi Ghag <aditi.ghag@isovalent.com>
---
 tools/testing/selftests/bpf/network_helpers.c | 23 +++++++++++++++++++
 tools/testing/selftests/bpf/network_helpers.h |  1 +
 2 files changed, 24 insertions(+)

diff --git a/tools/testing/selftests/bpf/network_helpers.c b/tools/testing/selftests/bpf/network_helpers.c
index 596caa176582..a105c0cd008a 100644
--- a/tools/testing/selftests/bpf/network_helpers.c
+++ b/tools/testing/selftests/bpf/network_helpers.c
@@ -427,3 +427,26 @@ void close_netns(struct nstoken *token)
 	close(token->orig_netns_fd);
 	free(token);
 }
+
+int get_socket_local_port(int sock_fd)
+{
+	struct sockaddr_storage addr;
+	socklen_t addrlen = sizeof(addr);
+	int err;
+
+	err = getsockname(sock_fd, (struct sockaddr *)&addr, &addrlen);
+	if (err < 0)
+		return err;
+
+	if (addr.ss_family == AF_INET) {
+		struct sockaddr_in *sin = (struct sockaddr_in *)&addr;
+
+		return sin->sin_port;
+	} else if (addr.ss_family == AF_INET6) {
+		struct sockaddr_in6 *sin = (struct sockaddr_in6 *)&addr;
+
+		return sin->sin6_port;
+	}
+
+	return -1;
+}
diff --git a/tools/testing/selftests/bpf/network_helpers.h b/tools/testing/selftests/bpf/network_helpers.h
index f882c691b790..694185644da6 100644
--- a/tools/testing/selftests/bpf/network_helpers.h
+++ b/tools/testing/selftests/bpf/network_helpers.h
@@ -56,6 +56,7 @@ int fastopen_connect(int server_fd, const char *data, unsigned int data_len,
 int make_sockaddr(int family, const char *addr_str, __u16 port,
 		  struct sockaddr_storage *addr, socklen_t *len);
 char *ping_command(int family);
+int get_socket_local_port(int sock_fd);
 
 struct nstoken;
 /**
-- 
2.34.1

[PATCH v7 bpf-next 08/10] selftests/bpf: Test bpf_sock_destroy

[Aditi Ghag]

The test cases for destroying sockets mirror the intended usages of the
bpf_sock_destroy kfunc using iterators.

The destroy helpers set `ECONNABORTED` error code that we can validate in
the test code with client sockets. But UDP sockets have an overriding error
code from the disconnect called during abort, so the error code the
validation is only done for TCP sockets.

Signed-off-by: Aditi Ghag <aditi.ghag@isovalent.com>
---
 .../selftests/bpf/prog_tests/sock_destroy.c   | 215 ++++++++++++++++++
 .../selftests/bpf/progs/sock_destroy_prog.c   | 145 ++++++++++++
 2 files changed, 360 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/sock_destroy.c
 create mode 100644 tools/testing/selftests/bpf/progs/sock_destroy_prog.c

diff --git a/tools/testing/selftests/bpf/prog_tests/sock_destroy.c b/tools/testing/selftests/bpf/prog_tests/sock_destroy.c
new file mode 100644
index 000000000000..d5f76731b4a3
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/sock_destroy.c
@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+#include <bpf/bpf_endian.h>
+
+#include "sock_destroy_prog.skel.h"
+#include "network_helpers.h"
+
+#define TEST_NS "sock_destroy_netns"
+
+static void start_iter_sockets(struct bpf_program *prog)
+{
+	struct bpf_link *link;
+	char buf[50] = {};
+	int iter_fd, len;
+
+	link = bpf_program__attach_iter(prog, NULL);
+	if (!ASSERT_OK_PTR(link, "attach_iter"))
+		return;
+
+	iter_fd = bpf_iter_create(bpf_link__fd(link));
+	if (!ASSERT_GE(iter_fd, 0, "create_iter"))
+		goto free_link;
+
+	while ((len = read(iter_fd, buf, sizeof(buf))) > 0)
+		;
+	ASSERT_GE(len, 0, "read");
+
+	close(iter_fd);
+
+free_link:
+	bpf_link__destroy(link);
+}
+
+static void test_tcp_client(struct sock_destroy_prog *skel)
+{
+	int serv = -1, clien = -1, n;
+
+	serv = start_server(AF_INET6, SOCK_STREAM, NULL, 0, 0);
+	if (!ASSERT_GE(serv, 0, "start_server"))
+		goto cleanup;
+
+	clien = connect_to_fd(serv, 0);
+	if (!ASSERT_GE(clien, 0, "connect_to_fd"))
+		goto cleanup;
+
+	serv = accept(serv, NULL, NULL);
+	if (!ASSERT_GE(serv, 0, "serv accept"))
+		goto cleanup;
+
+	n = send(clien, "t", 1, 0);
+	if (!ASSERT_EQ(n, 1, "client send"))
+		goto cleanup;
+
+	/* Run iterator program that destroys connected client sockets. */
+	start_iter_sockets(skel->progs.iter_tcp6_client);
+
+	n = send(clien, "t", 1, 0);
+	if (!ASSERT_LT(n, 0, "client_send on destroyed socket"))
+		goto cleanup;
+	ASSERT_EQ(errno, ECONNABORTED, "error code on destroyed socket");
+
+cleanup:
+	if (clien != -1)
+		close(clien);
+	if (serv != -1)
+		close(serv);
+}
+
+static void test_tcp_server(struct sock_destroy_prog *skel)
+{
+	int serv = -1, clien = -1, n, serv_port;
+
+	serv = start_server(AF_INET6, SOCK_STREAM, NULL, 0, 0);
+	if (!ASSERT_GE(serv, 0, "start_server"))
+		goto cleanup;
+	serv_port = get_socket_local_port(serv);
+	if (!ASSERT_GE(serv_port, 0, "get_sock_local_port"))
+		goto cleanup;
+	skel->bss->serv_port = (__be16) serv_port;
+
+	clien = connect_to_fd(serv, 0);
+	if (!ASSERT_GE(clien, 0, "connect_to_fd"))
+		goto cleanup;
+
+	serv = accept(serv, NULL, NULL);
+	if (!ASSERT_GE(serv, 0, "serv accept"))
+		goto cleanup;
+
+	n = send(clien, "t", 1, 0);
+	if (!ASSERT_EQ(n, 1, "client send"))
+		goto cleanup;
+
+	/* Run iterator program that destroys server sockets. */
+	start_iter_sockets(skel->progs.iter_tcp6_server);
+
+	n = send(clien, "t", 1, 0);
+	if (!ASSERT_LT(n, 0, "client_send on destroyed socket"))
+		goto cleanup;
+	ASSERT_EQ(errno, ECONNRESET, "error code on destroyed socket");
+
+cleanup:
+	if (clien != -1)
+		close(clien);
+	if (serv != -1)
+		close(serv);
+}
+
+static void test_udp_client(struct sock_destroy_prog *skel)
+{
+	int serv = -1, clien = -1, n = 0;
+
+	serv = start_server(AF_INET6, SOCK_DGRAM, NULL, 0, 0);
+	if (!ASSERT_GE(serv, 0, "start_server"))
+		goto cleanup;
+
+	clien = connect_to_fd(serv, 0);
+	if (!ASSERT_GE(clien, 0, "connect_to_fd"))
+		goto cleanup;
+
+	n = send(clien, "t", 1, 0);
+	if (!ASSERT_EQ(n, 1, "client send"))
+		goto cleanup;
+
+	/* Run iterator program that destroys sockets. */
+	start_iter_sockets(skel->progs.iter_udp6_client);
+
+	n = send(clien, "t", 1, 0);
+	if (!ASSERT_LT(n, 0, "client_send on destroyed socket"))
+		goto cleanup;
+	/* UDP sockets have an overriding error code after they are disconnected,
+	 * so we don't check for ECONNABORTED error code.
+	 */
+
+cleanup:
+	if (clien != -1)
+		close(clien);
+	if (serv != -1)
+		close(serv);
+}
+
+static void test_udp_server(struct sock_destroy_prog *skel)
+{
+	int *listen_fds = NULL, n, i, serv_port;
+	unsigned int num_listens = 5;
+	char buf[1];
+
+	/* Start reuseport servers. */
+	listen_fds = start_reuseport_server(AF_INET6, SOCK_DGRAM,
+					    "::1", 0, 0, num_listens);
+	if (!ASSERT_OK_PTR(listen_fds, "start_reuseport_server"))
+		goto cleanup;
+	serv_port = get_socket_local_port(listen_fds[0]);
+	if (!ASSERT_GE(serv_port, 0, "get_sock_local_port"))
+		goto cleanup;
+	skel->bss->serv_port = (__be16) serv_port;
+
+	/* Run iterator program that destroys server sockets. */
+	start_iter_sockets(skel->progs.iter_udp6_server);
+
+	for (i = 0; i < num_listens; ++i) {
+		n = read(listen_fds[i], buf, sizeof(buf));
+		if (!ASSERT_EQ(n, -1, "read") ||
+		    !ASSERT_EQ(errno, ECONNABORTED, "error code on destroyed socket"))
+			break;
+	}
+	ASSERT_EQ(i, num_listens, "server socket");
+
+cleanup:
+	free_fds(listen_fds, num_listens);
+}
+
+void test_sock_destroy(void)
+{
+	struct sock_destroy_prog *skel;
+	struct nstoken *nstoken;
+	int cgroup_fd;
+
+	skel = sock_destroy_prog__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		return;
+
+	cgroup_fd = test__join_cgroup("/sock_destroy");
+	if (!ASSERT_GE(cgroup_fd, 0, "join_cgroup"))
+		goto cleanup;
+
+	skel->links.sock_connect = bpf_program__attach_cgroup(
+		skel->progs.sock_connect, cgroup_fd);
+	if (!ASSERT_OK_PTR(skel->links.sock_connect, "prog_attach"))
+		goto cleanup;
+
+	SYS(cleanup, "ip netns add %s", TEST_NS);
+	SYS(cleanup, "ip -net %s link set dev lo up", TEST_NS);
+
+	nstoken = open_netns(TEST_NS);
+	if (!ASSERT_OK_PTR(nstoken, "open_netns"))
+		goto cleanup;
+
+	if (test__start_subtest("tcp_client"))
+		test_tcp_client(skel);
+	if (test__start_subtest("tcp_server"))
+		test_tcp_server(skel);
+	if (test__start_subtest("udp_client"))
+		test_udp_client(skel);
+	if (test__start_subtest("udp_server"))
+		test_udp_server(skel);
+
+
+cleanup:
+	if (nstoken)
+		close_netns(nstoken);
+	SYS_NOFAIL("ip netns del " TEST_NS " &> /dev/null");
+	if (cgroup_fd >= 0)
+		close(cgroup_fd);
+	sock_destroy_prog__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/sock_destroy_prog.c b/tools/testing/selftests/bpf/progs/sock_destroy_prog.c
new file mode 100644
index 000000000000..9e0bf7a54cec
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/sock_destroy_prog.c
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_endian.h>
+
+#include "bpf_tracing_net.h"
+
+__be16 serv_port = 0;
+
+int bpf_sock_destroy(struct sock_common *sk) __ksym;
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, __u64);
+} tcp_conn_sockets SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, __u64);
+} udp_conn_sockets SEC(".maps");
+
+SEC("cgroup/connect6")
+int sock_connect(struct bpf_sock_addr *ctx)
+{
+	__u64 sock_cookie = 0;
+	int key = 0;
+	__u32 keyc = 0;
+
+	if (ctx->family != AF_INET6 || ctx->user_family != AF_INET6)
+		return 1;
+
+	sock_cookie = bpf_get_socket_cookie(ctx);
+	if (ctx->protocol == IPPROTO_TCP)
+		bpf_map_update_elem(&tcp_conn_sockets, &key, &sock_cookie, 0);
+	else if (ctx->protocol == IPPROTO_UDP)
+		bpf_map_update_elem(&udp_conn_sockets, &keyc, &sock_cookie, 0);
+	else
+		return 1;
+
+	return 1;
+}
+
+SEC("iter/tcp")
+int iter_tcp6_client(struct bpf_iter__tcp *ctx)
+{
+	struct sock_common *sk_common = ctx->sk_common;
+	__u64 sock_cookie = 0;
+	__u64 *val;
+	int key = 0;
+
+	if (!sk_common)
+		return 0;
+
+	if (sk_common->skc_family != AF_INET6)
+		return 0;
+
+	sock_cookie  = bpf_get_socket_cookie(sk_common);
+	val = bpf_map_lookup_elem(&tcp_conn_sockets, &key);
+	if (!val)
+		return 0;
+	/* Destroy connected client sockets. */
+	if (sock_cookie == *val)
+		bpf_sock_destroy(sk_common);
+
+	return 0;
+}
+
+SEC("iter/tcp")
+int iter_tcp6_server(struct bpf_iter__tcp *ctx)
+{
+	struct sock_common *sk_common = ctx->sk_common;
+	const struct inet_connection_sock *icsk;
+	const struct inet_sock *inet;
+	struct tcp6_sock *tcp_sk;
+	__be16 srcp;
+
+	if (!sk_common)
+		return 0;
+
+	if (sk_common->skc_family != AF_INET6)
+		return 0;
+
+	tcp_sk = bpf_skc_to_tcp6_sock(sk_common);
+	if (!tcp_sk)
+		return 0;
+
+	icsk = &tcp_sk->tcp.inet_conn;
+	inet = &icsk->icsk_inet;
+	srcp = inet->inet_sport;
+
+	/* Destroy server sockets. */
+	if (srcp == serv_port)
+		bpf_sock_destroy(sk_common);
+
+	return 0;
+}
+
+
+SEC("iter/udp")
+int iter_udp6_client(struct bpf_iter__udp *ctx)
+{
+	struct udp_sock *udp_sk = ctx->udp_sk;
+	struct sock *sk = (struct sock *) udp_sk;
+	__u64 sock_cookie = 0, *val;
+	int key = 0;
+
+	if (!sk)
+		return 0;
+
+	sock_cookie  = bpf_get_socket_cookie(sk);
+	val = bpf_map_lookup_elem(&udp_conn_sockets, &key);
+	if (!val)
+		return 0;
+	/* Destroy connected client sockets. */
+	if (sock_cookie == *val)
+		bpf_sock_destroy((struct sock_common *)sk);
+
+	return 0;
+}
+
+SEC("iter/udp")
+int iter_udp6_server(struct bpf_iter__udp *ctx)
+{
+	struct udp_sock *udp_sk = ctx->udp_sk;
+	struct sock *sk = (struct sock *) udp_sk;
+	struct inet_sock *inet;
+	__be16 srcp;
+
+	if (!sk)
+		return 0;
+
+	inet = &udp_sk->inet;
+	srcp = inet->inet_sport;
+	if (srcp == serv_port)
+		bpf_sock_destroy((struct sock_common *)sk);
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";
-- 
2.34.1

[PATCH v7 bpf-next 09/10] bpf: Add a kfunc filter function to 'struct btf_kfunc_id_set'

[Aditi Ghag]

This commit adds the ability to filter kfuncs to certain BPF program
types, and thereby limits bpf_sock_destroy kfunc to progras with attach
type 'BPF_TRACE_ITER'.
Previous patches introduced 'bpf_sock_destroy kfunc' that can only be
called from BPF (sockets) iterator type programs.  The reason being, the
kfunc requires lock_sock to be done from the BPF context prior to
calling the kfunc.
To that end, the patch adds a callback filter to 'struct
btf_kfunc_id_set'.  The filter has access to the prog construct
including other properties of the prog.  For the bpf_sock_destroy case,
the `expected_attached_type` property of a prog construct is used to
allow access to the kfunc in the provided callback filter.

Signed-off-by: Aditi Ghag <aditi.ghag@isovalent.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
---
 include/linux/btf.h   | 18 ++++++++-----
 kernel/bpf/btf.c      | 59 +++++++++++++++++++++++++++++++++++--------
 kernel/bpf/verifier.c |  7 ++---
 net/core/filter.c     |  9 +++++++
 4 files changed, 73 insertions(+), 20 deletions(-)

diff --git a/include/linux/btf.h b/include/linux/btf.h
index 495250162422..918a0b6379bd 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -99,10 +99,14 @@ struct btf_type;
 union bpf_attr;
 struct btf_show;
 struct btf_id_set;
+struct bpf_prog;
+
+typedef int (*btf_kfunc_filter_t)(const struct bpf_prog *prog, u32 kfunc_id);
 
 struct btf_kfunc_id_set {
 	struct module *owner;
 	struct btf_id_set8 *set;
+	btf_kfunc_filter_t filter;
 };
 
 struct btf_id_dtor_kfunc {
@@ -482,7 +486,6 @@ static inline void *btf_id_set8_contains(const struct btf_id_set8 *set, u32 id)
 	return bsearch(&id, set->pairs, set->cnt, sizeof(set->pairs[0]), btf_id_cmp_func);
 }
 
-struct bpf_prog;
 struct bpf_verifier_log;
 
 #ifdef CONFIG_BPF_SYSCALL
@@ -490,10 +493,10 @@ const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id);
 const char *btf_name_by_offset(const struct btf *btf, u32 offset);
 struct btf *btf_parse_vmlinux(void);
 struct btf *bpf_prog_get_target_btf(const struct bpf_prog *prog);
-u32 *btf_kfunc_id_set_contains(const struct btf *btf,
-			       enum bpf_prog_type prog_type,
-			       u32 kfunc_btf_id);
-u32 *btf_kfunc_is_modify_return(const struct btf *btf, u32 kfunc_btf_id);
+u32 *btf_kfunc_id_set_contains(const struct btf *btf, u32 kfunc_btf_id,
+			       const struct bpf_prog *prog);
+u32 *btf_kfunc_is_modify_return(const struct btf *btf, u32 kfunc_btf_id,
+				const struct bpf_prog *prog);
 int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
 			      const struct btf_kfunc_id_set *s);
 int register_btf_fmodret_id_set(const struct btf_kfunc_id_set *kset);
@@ -520,8 +523,9 @@ static inline const char *btf_name_by_offset(const struct btf *btf,
 	return NULL;
 }
 static inline u32 *btf_kfunc_id_set_contains(const struct btf *btf,
-					     enum bpf_prog_type prog_type,
-					     u32 kfunc_btf_id)
+					     u32 kfunc_btf_id,
+					     struct bpf_prog *prog)
+
 {
 	return NULL;
 }
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 913b9d717a4a..c6dae44e236d 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -218,10 +218,17 @@ enum btf_kfunc_hook {
 enum {
 	BTF_KFUNC_SET_MAX_CNT = 256,
 	BTF_DTOR_KFUNC_MAX_CNT = 256,
+	BTF_KFUNC_FILTER_MAX_CNT = 16,
+};
+
+struct btf_kfunc_hook_filter {
+	btf_kfunc_filter_t filters[BTF_KFUNC_FILTER_MAX_CNT];
+	u32 nr_filters;
 };
 
 struct btf_kfunc_set_tab {
 	struct btf_id_set8 *sets[BTF_KFUNC_HOOK_MAX];
+	struct btf_kfunc_hook_filter hook_filters[BTF_KFUNC_HOOK_MAX];
 };
 
 struct btf_id_dtor_kfunc_tab {
@@ -7720,9 +7727,12 @@ static int btf_check_kfunc_protos(struct btf *btf, u32 func_id, u32 func_flags)
 /* Kernel Function (kfunc) BTF ID set registration API */
 
 static int btf_populate_kfunc_set(struct btf *btf, enum btf_kfunc_hook hook,
-				  struct btf_id_set8 *add_set)
+				  const struct btf_kfunc_id_set *kset)
 {
+	struct btf_kfunc_hook_filter *hook_filter;
+	struct btf_id_set8 *add_set = kset->set;
 	bool vmlinux_set = !btf_is_module(btf);
+	bool add_filter = !!kset->filter;
 	struct btf_kfunc_set_tab *tab;
 	struct btf_id_set8 *set;
 	u32 set_cnt;
@@ -7737,6 +7747,20 @@ static int btf_populate_kfunc_set(struct btf *btf, enum btf_kfunc_hook hook,
 		return 0;
 
 	tab = btf->kfunc_set_tab;
+
+	if (tab && add_filter) {
+		int i;
+
+		hook_filter = &tab->hook_filters[hook];
+		for (i = 0; i < hook_filter->nr_filters; i++) {
+			if (hook_filter->filters[i] == kset->filter)
+				add_filter = false;
+		}
+
+		if (add_filter && hook_filter->nr_filters == BTF_KFUNC_FILTER_MAX_CNT)
+			return -E2BIG;
+	}
+
 	if (!tab) {
 		tab = kzalloc(sizeof(*tab), GFP_KERNEL | __GFP_NOWARN);
 		if (!tab)
@@ -7759,7 +7783,7 @@ static int btf_populate_kfunc_set(struct btf *btf, enum btf_kfunc_hook hook,
 	 */
 	if (!vmlinux_set) {
 		tab->sets[hook] = add_set;
-		return 0;
+		goto do_add_filter;
 	}
 
 	/* In case of vmlinux sets, there may be more than one set being
@@ -7801,6 +7825,11 @@ static int btf_populate_kfunc_set(struct btf *btf, enum btf_kfunc_hook hook,
 
 	sort(set->pairs, set->cnt, sizeof(set->pairs[0]), btf_id_cmp_func, NULL);
 
+do_add_filter:
+	if (add_filter) {
+		hook_filter = &tab->hook_filters[hook];
+		hook_filter->filters[hook_filter->nr_filters++] = kset->filter;
+	}
 	return 0;
 end:
 	btf_free_kfunc_set_tab(btf);
@@ -7809,15 +7838,22 @@ static int btf_populate_kfunc_set(struct btf *btf, enum btf_kfunc_hook hook,
 
 static u32 *__btf_kfunc_id_set_contains(const struct btf *btf,
 					enum btf_kfunc_hook hook,
+					const struct bpf_prog *prog,
 					u32 kfunc_btf_id)
 {
+	struct btf_kfunc_hook_filter *hook_filter;
 	struct btf_id_set8 *set;
-	u32 *id;
+	u32 *id, i;
 
 	if (hook >= BTF_KFUNC_HOOK_MAX)
 		return NULL;
 	if (!btf->kfunc_set_tab)
 		return NULL;
+	hook_filter = &btf->kfunc_set_tab->hook_filters[hook];
+	for (i = 0; i < hook_filter->nr_filters; i++) {
+		if (hook_filter->filters[i](prog, kfunc_btf_id))
+			return NULL;
+	}
 	set = btf->kfunc_set_tab->sets[hook];
 	if (!set)
 		return NULL;
@@ -7870,23 +7906,25 @@ static int bpf_prog_type_to_kfunc_hook(enum bpf_prog_type prog_type)
  * protection for looking up a well-formed btf->kfunc_set_tab.
  */
 u32 *btf_kfunc_id_set_contains(const struct btf *btf,
-			       enum bpf_prog_type prog_type,
-			       u32 kfunc_btf_id)
+			       u32 kfunc_btf_id,
+			       const struct bpf_prog *prog)
 {
+	enum bpf_prog_type prog_type = resolve_prog_type(prog);
 	enum btf_kfunc_hook hook;
 	u32 *kfunc_flags;
 
-	kfunc_flags = __btf_kfunc_id_set_contains(btf, BTF_KFUNC_HOOK_COMMON, kfunc_btf_id);
+	kfunc_flags = __btf_kfunc_id_set_contains(btf, BTF_KFUNC_HOOK_COMMON, prog, kfunc_btf_id);
 	if (kfunc_flags)
 		return kfunc_flags;
 
 	hook = bpf_prog_type_to_kfunc_hook(prog_type);
-	return __btf_kfunc_id_set_contains(btf, hook, kfunc_btf_id);
+	return __btf_kfunc_id_set_contains(btf, hook, prog, kfunc_btf_id);
 }
 
-u32 *btf_kfunc_is_modify_return(const struct btf *btf, u32 kfunc_btf_id)
+u32 *btf_kfunc_is_modify_return(const struct btf *btf, u32 kfunc_btf_id,
+				const struct bpf_prog *prog)
 {
-	return __btf_kfunc_id_set_contains(btf, BTF_KFUNC_HOOK_FMODRET, kfunc_btf_id);
+	return __btf_kfunc_id_set_contains(btf, BTF_KFUNC_HOOK_FMODRET, prog, kfunc_btf_id);
 }
 
 static int __register_btf_kfunc_id_set(enum btf_kfunc_hook hook,
@@ -7917,7 +7955,8 @@ static int __register_btf_kfunc_id_set(enum btf_kfunc_hook hook,
 			goto err_out;
 	}
 
-	ret = btf_populate_kfunc_set(btf, hook, kset->set);
+	ret = btf_populate_kfunc_set(btf, hook, kset);
+
 err_out:
 	btf_put(btf);
 	return ret;
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index d6db6de3e9ea..8d9519210935 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -10534,7 +10534,7 @@ static int fetch_kfunc_meta(struct bpf_verifier_env *env,
 		*kfunc_name = func_name;
 	func_proto = btf_type_by_id(desc_btf, func->type);
 
-	kfunc_flags = btf_kfunc_id_set_contains(desc_btf, resolve_prog_type(env->prog), func_id);
+	kfunc_flags = btf_kfunc_id_set_contains(desc_btf, func_id, env->prog);
 	if (!kfunc_flags) {
 		return -EACCES;
 	}
@@ -18526,7 +18526,8 @@ int bpf_check_attach_target(struct bpf_verifier_log *log,
 				 * in the fmodret id set with the KF_SLEEPABLE flag.
 				 */
 				else {
-					u32 *flags = btf_kfunc_is_modify_return(btf, btf_id);
+					u32 *flags = btf_kfunc_is_modify_return(btf, btf_id,
+										prog);
 
 					if (flags && (*flags & KF_SLEEPABLE))
 						ret = 0;
@@ -18554,7 +18555,7 @@ int bpf_check_attach_target(struct bpf_verifier_log *log,
 				return -EINVAL;
 			}
 			ret = -EINVAL;
-			if (btf_kfunc_is_modify_return(btf, btf_id) ||
+			if (btf_kfunc_is_modify_return(btf, btf_id, prog) ||
 			    !check_attach_modify_return(addr, tname))
 				ret = 0;
 			if (ret) {
diff --git a/net/core/filter.c b/net/core/filter.c
index 97d70b7959a1..20c603321325 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -11762,9 +11762,18 @@ BTF_SET8_START(sock_destroy_kfunc_set)
 BTF_ID_FLAGS(func, bpf_sock_destroy)
 BTF_SET8_END(sock_destroy_kfunc_set)
 
+static int tracing_iter_filter(const struct bpf_prog *prog, u32 kfunc_id)
+{
+	if (btf_id_set8_contains(&sock_destroy_kfunc_set, kfunc_id) &&
+	    prog->expected_attach_type != BPF_TRACE_ITER)
+		return -EACCES;
+	return 0;
+}
+
 static const struct btf_kfunc_id_set bpf_sock_destroy_kfunc_set = {
 	.owner = THIS_MODULE,
 	.set   = &sock_destroy_kfunc_set,
+	.filter = tracing_iter_filter,
 };
 
 static int init_subsystem(void)
-- 
2.34.1

[PATCH v7 bpf-next 10/10] selftests/bpf: Extend bpf_sock_destroy tests

[Aditi Ghag]

This commit adds a test case to verify that the
bpf_sock_destroy kfunc is not allowed from
program attach types other than BPF trace iterator.
Unsupprted programs calling the kfunc will be rejected by
the verifier.

Signed-off-by: Aditi Ghag <aditi.ghag@isovalent.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
---
 .../selftests/bpf/prog_tests/sock_destroy.c   |  2 ++
 .../bpf/progs/sock_destroy_prog_fail.c        | 22 +++++++++++++++++++
 2 files changed, 24 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/sock_destroy_prog_fail.c

diff --git a/tools/testing/selftests/bpf/prog_tests/sock_destroy.c b/tools/testing/selftests/bpf/prog_tests/sock_destroy.c
index d5f76731b4a3..8f7d745e55a1 100644
--- a/tools/testing/selftests/bpf/prog_tests/sock_destroy.c
+++ b/tools/testing/selftests/bpf/prog_tests/sock_destroy.c
@@ -3,6 +3,7 @@
 #include <bpf/bpf_endian.h>
 
 #include "sock_destroy_prog.skel.h"
+#include "sock_destroy_prog_fail.skel.h"
 #include "network_helpers.h"
 
 #define TEST_NS "sock_destroy_netns"
@@ -204,6 +205,7 @@ void test_sock_destroy(void)
 	if (test__start_subtest("udp_server"))
 		test_udp_server(skel);
 
+	RUN_TESTS(sock_destroy_prog_fail);
 
 cleanup:
 	if (nstoken)
diff --git a/tools/testing/selftests/bpf/progs/sock_destroy_prog_fail.c b/tools/testing/selftests/bpf/progs/sock_destroy_prog_fail.c
new file mode 100644
index 000000000000..dd6850b58e25
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/sock_destroy_prog_fail.c
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_helpers.h>
+
+#include "bpf_misc.h"
+
+char _license[] SEC("license") = "GPL";
+
+int bpf_sock_destroy(struct sock_common *sk) __ksym;
+
+SEC("tp_btf/tcp_destroy_sock")
+__failure __msg("calling kernel function bpf_sock_destroy is not allowed")
+int BPF_PROG(trace_tcp_destroy_sock, struct sock *sk)
+{
+	/* should not load */
+	bpf_sock_destroy((struct sock_common *)sk);
+
+	return 0;
+}
+
-- 
2.34.1

Re: [PATCH v7 bpf-next 04/10] udp: seq_file: Remove bpf_seq_afinfo from udp_iter_state

[Aditi Ghag]

> On May 3, 2023, at 3:53 PM, Aditi Ghag <aditi.ghag@isovalent.com> wrote:
> 
> This is a preparatory commit to remove the field. The field was
> previously shared between proc fs and BPF UDP socket iterators. As the
> follow-up commits will decouple the implementation for the iterators,
> remove the field. As for BPF socket iterator, filtering of sockets is
> exepected to be done in BPF programs.
> 
> Suggested-by: Martin KaFai Lau <martin.lau@kernel.org>
> Signed-off-by: Aditi Ghag <aditi.ghag@isovalent.com>
> ---
> include/net/udp.h |  1 -
> net/ipv4/udp.c    | 25 +++++--------------------
> 2 files changed, 5 insertions(+), 21 deletions(-)
> 
> diff --git a/include/net/udp.h b/include/net/udp.h
> index de4b528522bb..5cad44318d71 100644
> --- a/include/net/udp.h
> +++ b/include/net/udp.h
> @@ -437,7 +437,6 @@ struct udp_seq_afinfo {
> struct udp_iter_state {
> 	struct seq_net_private  p;
> 	int			bucket;
> -	struct udp_seq_afinfo	*bpf_seq_afinfo;
> };
> 
> void *udp_seq_start(struct seq_file *seq, loff_t *pos);
> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> index c426ebafeb13..9f8c1554a9e4 100644
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -2993,14 +2993,16 @@ static bool seq_sk_match(struct seq_file *seq, const struct sock *sk)
> 		net_eq(sock_net(sk), seq_file_net(seq)));
> }
> 
> +static const struct seq_operations bpf_iter_udp_seq_ops;

>> net/ipv4/udp.c:3001:36: warning: 'bpf_iter_udp_seq_ops' defined but not used [-Wunused-const-variable=]
   3001 | static const struct seq_operations bpf_iter_udp_seq_ops;
        |                                    ^~~~~~~~~~~~~~~~~~~~

This would have to be wrapped with ifdef too. 

> static struct udp_table *udp_get_table_seq(struct seq_file *seq,
> 					   struct net *net)
> {
> -	const struct udp_iter_state *state = seq->private;
> 	const struct udp_seq_afinfo *afinfo;
> 
> -	if (state->bpf_seq_afinfo)
> +#ifdef CONFIG_BPF_SYSCALL
> +	if (seq->op == &bpf_iter_udp_seq_ops)
> 		return net->ipv4.udp_table;
> +#endif
> 
> 	afinfo = pde_data(file_inode(seq->file));
> 	return afinfo->udp_table ? : net->ipv4.udp_table;
> @@ -3424,28 +3426,11 @@ DEFINE_BPF_ITER_FUNC(udp, struct bpf_iter_meta *meta,
> 
> static int bpf_iter_init_udp(void *priv_data, struct bpf_iter_aux_info *aux)
> {
> -	struct udp_iter_state *st = priv_data;
> -	struct udp_seq_afinfo *afinfo;
> -	int ret;
> -
> -	afinfo = kmalloc(sizeof(*afinfo), GFP_USER | __GFP_NOWARN);
> -	if (!afinfo)
> -		return -ENOMEM;
> -
> -	afinfo->family = AF_UNSPEC;
> -	afinfo->udp_table = NULL;
> -	st->bpf_seq_afinfo = afinfo;
> -	ret = bpf_iter_init_seq_net(priv_data, aux);
> -	if (ret)
> -		kfree(afinfo);
> -	return ret;
> +	return bpf_iter_init_seq_net(priv_data, aux);
> }
> 
> static void bpf_iter_fini_udp(void *priv_data)
> {
> -	struct udp_iter_state *st = priv_data;
> -
> -	kfree(st->bpf_seq_afinfo);
> 	bpf_iter_fini_seq_net(priv_data);
> }
> 
> -- 
> 2.34.1
> 

Re: [PATCH v7 bpf-next 07/10] selftests/bpf: Add helper to get port using getsockname

[Stanislav Fomichev]

On 05/03, Aditi Ghag wrote:
> The helper will be used to programmatically retrieve,
> and pass ports in userspace and kernel selftest programs.
> 
> Suggested-by: Stanislav Fomichev <sdf@google.com>
> Signed-off-by: Aditi Ghag <aditi.ghag@isovalent.com>

Acked-by: Stanislav Fomichev <sdf@google.com>

Looks great, thank you!

> ---
>  tools/testing/selftests/bpf/network_helpers.c | 23 +++++++++++++++++++
>  tools/testing/selftests/bpf/network_helpers.h |  1 +
>  2 files changed, 24 insertions(+)
> 
> diff --git a/tools/testing/selftests/bpf/network_helpers.c b/tools/testing/selftests/bpf/network_helpers.c
> index 596caa176582..a105c0cd008a 100644
> --- a/tools/testing/selftests/bpf/network_helpers.c
> +++ b/tools/testing/selftests/bpf/network_helpers.c
> @@ -427,3 +427,26 @@ void close_netns(struct nstoken *token)
>  	close(token->orig_netns_fd);
>  	free(token);
>  }
> +
> +int get_socket_local_port(int sock_fd)
> +{
> +	struct sockaddr_storage addr;
> +	socklen_t addrlen = sizeof(addr);
> +	int err;
> +
> +	err = getsockname(sock_fd, (struct sockaddr *)&addr, &addrlen);
> +	if (err < 0)
> +		return err;
> +
> +	if (addr.ss_family == AF_INET) {
> +		struct sockaddr_in *sin = (struct sockaddr_in *)&addr;
> +
> +		return sin->sin_port;
> +	} else if (addr.ss_family == AF_INET6) {
> +		struct sockaddr_in6 *sin = (struct sockaddr_in6 *)&addr;
> +
> +		return sin->sin6_port;
> +	}
> +
> +	return -1;
> +}
> diff --git a/tools/testing/selftests/bpf/network_helpers.h b/tools/testing/selftests/bpf/network_helpers.h
> index f882c691b790..694185644da6 100644
> --- a/tools/testing/selftests/bpf/network_helpers.h
> +++ b/tools/testing/selftests/bpf/network_helpers.h
> @@ -56,6 +56,7 @@ int fastopen_connect(int server_fd, const char *data, unsigned int data_len,
>  int make_sockaddr(int family, const char *addr_str, __u16 port,
>  		  struct sockaddr_storage *addr, socklen_t *len);
>  char *ping_command(int family);
> +int get_socket_local_port(int sock_fd);
>  
>  struct nstoken;
>  /**
> -- 
> 2.34.1
> 

Re: [PATCH v7 bpf-next 06/10] bpf: Add bpf_sock_destroy kfunc

[Martin KaFai Lau]

On 5/3/23 3:53 PM, Aditi Ghag wrote:
> diff --git a/net/core/filter.c b/net/core/filter.c
> index 727c5269867d..97d70b7959a1 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -11715,3 +11715,60 @@ static int __init bpf_kfunc_init(void)
>   	return ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &bpf_kfunc_set_xdp);
>   }
>   late_initcall(bpf_kfunc_init);
> +
> +/* Disables missing prototype warnings */
> +__diag_push();
> +__diag_ignore_all("-Wmissing-prototypes",
> +		  "Global functions as their definitions will be in vmlinux BTF");
> +
> +/* bpf_sock_destroy: Destroy the given socket with ECONNABORTED error code.
> + *
> + * The function expects a non-NULL pointer to a socket, and invokes the
> + * protocol specific socket destroy handlers.
> + *
> + * The helper can only be called from BPF contexts that have acquired the socket
> + * locks.
> + *
> + * Parameters:
> + * @sock: Pointer to socket to be destroyed
> + *
> + * Return:
> + * On error, may return EPROTONOSUPPORT, EINVAL.
> + * EPROTONOSUPPORT if protocol specific destroy handler is not supported.
> + * 0 otherwise
> + */
> +__bpf_kfunc int bpf_sock_destroy(struct sock_common *sock)
> +{
> +	struct sock *sk = (struct sock *)sock;
> +
> +	if (!sk)

If the kfunc has the KF_TRUSTED_ARGS flag, this NULL test is no longer needed. 
More details below.

> +		return -EINVAL;
> +
> +	/* The locking semantics that allow for synchronous execution of the
> +	 * destroy handlers are only supported for TCP and UDP.
> +	 * Supporting protocols will need to acquire lock_sock in the BPF context
> +	 * prior to invoking this kfunc.
> +	 */
> +	if (!sk->sk_prot->diag_destroy || (sk->sk_protocol != IPPROTO_TCP &&
> +					   sk->sk_protocol != IPPROTO_UDP))
> +		return -EOPNOTSUPP;
> +
> +	return sk->sk_prot->diag_destroy(sk, ECONNABORTED);
> +}
> +
> +__diag_pop()
> +
> +BTF_SET8_START(sock_destroy_kfunc_set)

nit. Rename it to a more generic name for future sk_iter related kfunc.
May be bpf_sk_iter_kfunc_set ?

> +BTF_ID_FLAGS(func, bpf_sock_destroy)

Follow up on the v6 patch-set regarding KF_TRUSTED_ARGS.
KF_TRUSTED_ARGS is needed here to avoid the cases where a PTR_TO_BTF_ID sk is 
obtained by following another pointer. eg. getting a sk pointer (may be even 
NULL) by following another sk pointer. The recent PTR_TRUSTED concept in the 
verifier can guard this. I tried and the following should do:

diff --git i/net/core/filter.c w/net/core/filter.c
index 68b228f3eca6..d82e038da0e3 100644
--- i/net/core/filter.c
+++ w/net/core/filter.c
@@ -11767,7 +11767,7 @@ __bpf_kfunc int bpf_sock_destroy(struct sock_common *sock)
  __diag_pop()

  BTF_SET8_START(sock_destroy_kfunc_set)
-BTF_ID_FLAGS(func, bpf_sock_destroy)
+BTF_ID_FLAGS(func, bpf_sock_destroy, KF_TRUSTED_ARGS)
  BTF_SET8_END(sock_destroy_kfunc_set)

  static int tracing_iter_filter(const struct bpf_prog *prog, u32 kfunc_id)
diff --git i/net/ipv4/tcp_ipv4.c w/net/ipv4/tcp_ipv4.c
index 887f83a90d85..a769284e8291 100644
--- i/net/ipv4/tcp_ipv4.c
+++ w/net/ipv4/tcp_ipv4.c
@@ -3354,7 +3354,7 @@ static struct bpf_iter_reg tcp_reg_info = {
  	.ctx_arg_info_size	= 1,
  	.ctx_arg_info		= {
  		{ offsetof(struct bpf_iter__tcp, sk_common),
-		  PTR_TO_BTF_ID_OR_NULL },
+		  PTR_TO_BTF_ID_OR_NULL | PTR_TRUSTED },
  	},
  	.get_func_proto		= bpf_iter_tcp_get_func_proto,
  	.seq_info		= &tcp_seq_info,
diff --git i/net/ipv4/udp.c w/net/ipv4/udp.c
index 746c85f2bb03..945b641b363b 100644
--- i/net/ipv4/udp.c
+++ w/net/ipv4/udp.c
@@ -3646,7 +3646,7 @@ static struct bpf_iter_reg udp_reg_info = {
  	.ctx_arg_info_size	= 1,
  	.ctx_arg_info		= {
  		{ offsetof(struct bpf_iter__udp, udp_sk),
-		  PTR_TO_BTF_ID_OR_NULL },
+		  PTR_TO_BTF_ID_OR_NULL | PTR_TRUSTED },
  	},
  	.seq_info		= &udp_seq_info,
  };

Please take a look and run through the test_progs. If you agree on the changes, 
this should be included in the same patch 6.

> +BTF_SET8_END(sock_destroy_kfunc_set)
> +
> +static const struct btf_kfunc_id_set bpf_sock_destroy_kfunc_set = {
> +	.owner = THIS_MODULE,
> +	.set   = &sock_destroy_kfunc_set,
> +};
> +
> +static int init_subsystem(void)
> +{
> +	return register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &bpf_sock_destroy_kfunc_set);
> +}
> +late_initcall(init_subsystem);
> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> index 288693981b00..2259b4facc2f 100644
> --- a/net/ipv4/tcp.c
> +++ b/net/ipv4/tcp.c
> @@ -4679,8 +4679,10 @@ int tcp_abort(struct sock *sk, int err)
>   		return 0;
>   	}
>   
> -	/* Don't race with userspace socket closes such as tcp_close. */
> -	lock_sock(sk);
> +	/* BPF context ensures sock locking. */
> +	if (!has_current_bpf_ctx())
> +		/* Don't race with userspace socket closes such as tcp_close. */
> +		lock_sock(sk);
>   
>   	if (sk->sk_state == TCP_LISTEN) {
>   		tcp_set_state(sk, TCP_CLOSE);
> @@ -4702,9 +4704,11 @@ int tcp_abort(struct sock *sk, int err)
>   	}
>   
>   	bh_unlock_sock(sk);
> +

nit. unnecessary new line change.

>   	local_bh_enable();
>   	tcp_write_queue_purge(sk);
> -	release_sock(sk);
> +	if (!has_current_bpf_ctx())
> +		release_sock(sk);
>   	return 0;
>   }
>   EXPORT_SYMBOL_GPL(tcp_abort);
> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> index 150551acab9d..5f48cdf82a45 100644
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -2925,7 +2925,8 @@ EXPORT_SYMBOL(udp_poll);
>   
>   int udp_abort(struct sock *sk, int err)
>   {
> -	lock_sock(sk);
> +	if (!has_current_bpf_ctx())
> +		lock_sock(sk);
>   
>   	/* udp{v6}_destroy_sock() sets it under the sk lock, avoid racing
>   	 * with close()
> @@ -2938,7 +2939,8 @@ int udp_abort(struct sock *sk, int err)
>   	__udp_disconnect(sk, 0);
>   
>   out:
> -	release_sock(sk);
> +	if (!has_current_bpf_ctx())
> +		release_sock(sk);
>   
>   	return 0;
>   }

Re: [PATCH v7 bpf-next 08/10] selftests/bpf: Test bpf_sock_destroy

[Martin KaFai Lau]

On 5/3/23 3:53 PM, Aditi Ghag wrote:
> The test cases for destroying sockets mirror the intended usages of the
> bpf_sock_destroy kfunc using iterators.
> 
> The destroy helpers set `ECONNABORTED` error code that we can validate in
> the test code with client sockets. But UDP sockets have an overriding error
> code from the disconnect called during abort, so the error code the
> validation is only done for TCP sockets.
> 
> Signed-off-by: Aditi Ghag <aditi.ghag@isovalent.com>
> ---
>   .../selftests/bpf/prog_tests/sock_destroy.c   | 215 ++++++++++++++++++
>   .../selftests/bpf/progs/sock_destroy_prog.c   | 145 ++++++++++++
>   2 files changed, 360 insertions(+)
>   create mode 100644 tools/testing/selftests/bpf/prog_tests/sock_destroy.c
>   create mode 100644 tools/testing/selftests/bpf/progs/sock_destroy_prog.c
> 
> diff --git a/tools/testing/selftests/bpf/prog_tests/sock_destroy.c b/tools/testing/selftests/bpf/prog_tests/sock_destroy.c
> new file mode 100644
> index 000000000000..d5f76731b4a3
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/sock_destroy.c
> @@ -0,0 +1,215 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <test_progs.h>
> +#include <bpf/bpf_endian.h>
> +
> +#include "sock_destroy_prog.skel.h"
> +#include "network_helpers.h"
> +
> +#define TEST_NS "sock_destroy_netns"
> +
> +static void start_iter_sockets(struct bpf_program *prog)
> +{
> +	struct bpf_link *link;
> +	char buf[50] = {};
> +	int iter_fd, len;
> +
> +	link = bpf_program__attach_iter(prog, NULL);
> +	if (!ASSERT_OK_PTR(link, "attach_iter"))
> +		return;
> +
> +	iter_fd = bpf_iter_create(bpf_link__fd(link));
> +	if (!ASSERT_GE(iter_fd, 0, "create_iter"))
> +		goto free_link;
> +
> +	while ((len = read(iter_fd, buf, sizeof(buf))) > 0)
> +		;
> +	ASSERT_GE(len, 0, "read");
> +
> +	close(iter_fd);
> +
> +free_link:
> +	bpf_link__destroy(link);
> +}
> +
> +static void test_tcp_client(struct sock_destroy_prog *skel)
> +{
> +	int serv = -1, clien = -1, n;
> +
> +	serv = start_server(AF_INET6, SOCK_STREAM, NULL, 0, 0);
> +	if (!ASSERT_GE(serv, 0, "start_server"))
> +		goto cleanup;
> +
> +	clien = connect_to_fd(serv, 0);
> +	if (!ASSERT_GE(clien, 0, "connect_to_fd"))
> +		goto cleanup;
> +
> +	serv = accept(serv, NULL, NULL);

The original serv fd is over-written and lost.

> +	if (!ASSERT_GE(serv, 0, "serv accept"))
> +		goto cleanup;
> +
> +	n = send(clien, "t", 1, 0);
> +	if (!ASSERT_EQ(n, 1, "client send"))
> +		goto cleanup;
> +
> +	/* Run iterator program that destroys connected client sockets. */
> +	start_iter_sockets(skel->progs.iter_tcp6_client);
> +
> +	n = send(clien, "t", 1, 0);
> +	if (!ASSERT_LT(n, 0, "client_send on destroyed socket"))
> +		goto cleanup;
> +	ASSERT_EQ(errno, ECONNABORTED, "error code on destroyed socket");
> +
> +cleanup:
> +	if (clien != -1)
> +		close(clien);
> +	if (serv != -1)
> +		close(serv);
> +}
> +
> +static void test_tcp_server(struct sock_destroy_prog *skel)
> +{
> +	int serv = -1, clien = -1, n, serv_port;
> +
> +	serv = start_server(AF_INET6, SOCK_STREAM, NULL, 0, 0);
> +	if (!ASSERT_GE(serv, 0, "start_server"))
> +		goto cleanup;
> +	serv_port = get_socket_local_port(serv);
> +	if (!ASSERT_GE(serv_port, 0, "get_sock_local_port"))
> +		goto cleanup;
> +	skel->bss->serv_port = (__be16) serv_port;
> +
> +	clien = connect_to_fd(serv, 0);
> +	if (!ASSERT_GE(clien, 0, "connect_to_fd"))
> +		goto cleanup;
> +
> +	serv = accept(serv, NULL, NULL);

Same here.

> +	if (!ASSERT_GE(serv, 0, "serv accept"))
> +		goto cleanup;
> +
> +	n = send(clien, "t", 1, 0);
> +	if (!ASSERT_EQ(n, 1, "client send"))
> +		goto cleanup;
> +
> +	/* Run iterator program that destroys server sockets. */
> +	start_iter_sockets(skel->progs.iter_tcp6_server);
> +
> +	n = send(clien, "t", 1, 0);
> +	if (!ASSERT_LT(n, 0, "client_send on destroyed socket"))
> +		goto cleanup;
> +	ASSERT_EQ(errno, ECONNRESET, "error code on destroyed socket");
> +
> +cleanup:
> +	if (clien != -1)
> +		close(clien);
> +	if (serv != -1)
> +		close(serv);
> +}
> +
> +static void test_udp_client(struct sock_destroy_prog *skel)
> +{
> +	int serv = -1, clien = -1, n = 0;
> +
> +	serv = start_server(AF_INET6, SOCK_DGRAM, NULL, 0, 0);
> +	if (!ASSERT_GE(serv, 0, "start_server"))
> +		goto cleanup;
> +
> +	clien = connect_to_fd(serv, 0);
> +	if (!ASSERT_GE(clien, 0, "connect_to_fd"))
> +		goto cleanup;
> +
> +	n = send(clien, "t", 1, 0);
> +	if (!ASSERT_EQ(n, 1, "client send"))
> +		goto cleanup;
> +
> +	/* Run iterator program that destroys sockets. */
> +	start_iter_sockets(skel->progs.iter_udp6_client);
> +
> +	n = send(clien, "t", 1, 0);
> +	if (!ASSERT_LT(n, 0, "client_send on destroyed socket"))
> +		goto cleanup;
> +	/* UDP sockets have an overriding error code after they are disconnected,
> +	 * so we don't check for ECONNABORTED error code.
> +	 */
> +
> +cleanup:
> +	if (clien != -1)
> +		close(clien);
> +	if (serv != -1)
> +		close(serv);
> +}
> +
> +static void test_udp_server(struct sock_destroy_prog *skel)
> +{
> +	int *listen_fds = NULL, n, i, serv_port;
> +	unsigned int num_listens = 5;
> +	char buf[1];
> +
> +	/* Start reuseport servers. */
> +	listen_fds = start_reuseport_server(AF_INET6, SOCK_DGRAM,
> +					    "::1", 0, 0, num_listens);
> +	if (!ASSERT_OK_PTR(listen_fds, "start_reuseport_server"))
> +		goto cleanup;
> +	serv_port = get_socket_local_port(listen_fds[0]);
> +	if (!ASSERT_GE(serv_port, 0, "get_sock_local_port"))
> +		goto cleanup;
> +	skel->bss->serv_port = (__be16) serv_port;
> +
> +	/* Run iterator program that destroys server sockets. */
> +	start_iter_sockets(skel->progs.iter_udp6_server);
> +
> +	for (i = 0; i < num_listens; ++i) {
> +		n = read(listen_fds[i], buf, sizeof(buf));
> +		if (!ASSERT_EQ(n, -1, "read") ||
> +		    !ASSERT_EQ(errno, ECONNABORTED, "error code on destroyed socket"))
> +			break;
> +	}
> +	ASSERT_EQ(i, num_listens, "server socket");
> +
> +cleanup:
> +	free_fds(listen_fds, num_listens);
> +}
> +
> +void test_sock_destroy(void)
> +{
> +	struct sock_destroy_prog *skel;
> +	struct nstoken *nstoken;

This does need a '= NULL;' now after consolidating to one "cleanup" label. Even 
the v6 patch needs a ' = NULL;' considering the SYS() below may do a goto also, 
so I was incorrect on my v6 comment and stand to be corrected by the compiler: 
https://github.com/kernel-patches/bpf/actions/runs/4877289517/jobs/8701781601

> +	int cgroup_fd;
> +
> +	skel = sock_destroy_prog__open_and_load();
> +	if (!ASSERT_OK_PTR(skel, "skel_open"))
> +		return;
> +
> +	cgroup_fd = test__join_cgroup("/sock_destroy");
> +	if (!ASSERT_GE(cgroup_fd, 0, "join_cgroup"))
> +		goto cleanup;
> +
> +	skel->links.sock_connect = bpf_program__attach_cgroup(
> +		skel->progs.sock_connect, cgroup_fd);
> +	if (!ASSERT_OK_PTR(skel->links.sock_connect, "prog_attach"))
> +		goto cleanup;
> +
> +	SYS(cleanup, "ip netns add %s", TEST_NS);
> +	SYS(cleanup, "ip -net %s link set dev lo up", TEST_NS);
> +
> +	nstoken = open_netns(TEST_NS);
> +	if (!ASSERT_OK_PTR(nstoken, "open_netns"))
> +		goto cleanup;
> +
> +	if (test__start_subtest("tcp_client"))
> +		test_tcp_client(skel);
> +	if (test__start_subtest("tcp_server"))
> +		test_tcp_server(skel);
> +	if (test__start_subtest("udp_client"))
> +		test_udp_client(skel);
> +	if (test__start_subtest("udp_server"))
> +		test_udp_server(skel);
> +
> +
> +cleanup:
> +	if (nstoken)
> +		close_netns(nstoken);
> +	SYS_NOFAIL("ip netns del " TEST_NS " &> /dev/null");
> +	if (cgroup_fd >= 0)
> +		close(cgroup_fd);
> +	sock_destroy_prog__destroy(skel);
> +}

Re: [PATCH v7 bpf-next 09/10] bpf: Add a kfunc filter function to 'struct btf_kfunc_id_set'

[Martin KaFai Lau]

On 5/3/23 3:53 PM, Aditi Ghag wrote:
> This commit adds the ability to filter kfuncs to certain BPF program
> types, and thereby limits bpf_sock_destroy kfunc to progras with attach

s/progras/program/

> type 'BPF_TRACE_ITER'.
> Previous patches introduced 'bpf_sock_destroy kfunc' that can only be
> called from BPF (sockets) iterator type programs.  The reason being, the
> kfunc requires lock_sock to be done from the BPF context prior to
> calling the kfunc.
> To that end, the patch adds a callback filter to 'struct
> btf_kfunc_id_set'.  The filter has access to the prog construct
> including other properties of the prog.  For the bpf_sock_destroy case,
> the `expected_attached_type` property of a prog construct is used to
> allow access to the kfunc in the provided callback filter.

Please also cc "David Vernet <void@manifault.com>" in the next respin.

Re: [PATCH v7 bpf-next 06/10] bpf: Add bpf_sock_destroy kfunc

[Martin KaFai Lau]

On 5/4/23 5:13 PM, Martin KaFai Lau wrote:
> 
> Follow up on the v6 patch-set regarding KF_TRUSTED_ARGS.
> KF_TRUSTED_ARGS is needed here to avoid the cases where a PTR_TO_BTF_ID sk is 
> obtained by following another pointer. eg. getting a sk pointer (may be even 
> NULL) by following another sk pointer. The recent PTR_TRUSTED concept in the 
> verifier can guard this. I tried and the following should do:
> 
> diff --git i/net/core/filter.c w/net/core/filter.c
> index 68b228f3eca6..d82e038da0e3 100644
> --- i/net/core/filter.c
> +++ w/net/core/filter.c
> @@ -11767,7 +11767,7 @@ __bpf_kfunc int bpf_sock_destroy(struct sock_common *sock)
>   __diag_pop()
> 
>   BTF_SET8_START(sock_destroy_kfunc_set)
> -BTF_ID_FLAGS(func, bpf_sock_destroy)
> +BTF_ID_FLAGS(func, bpf_sock_destroy, KF_TRUSTED_ARGS)
>   BTF_SET8_END(sock_destroy_kfunc_set)
> 
>   static int tracing_iter_filter(const struct bpf_prog *prog, u32 kfunc_id)
> diff --git i/net/ipv4/tcp_ipv4.c w/net/ipv4/tcp_ipv4.c
> index 887f83a90d85..a769284e8291 100644
> --- i/net/ipv4/tcp_ipv4.c
> +++ w/net/ipv4/tcp_ipv4.c
> @@ -3354,7 +3354,7 @@ static struct bpf_iter_reg tcp_reg_info = {
>       .ctx_arg_info_size    = 1,
>       .ctx_arg_info        = {
>           { offsetof(struct bpf_iter__tcp, sk_common),
> -          PTR_TO_BTF_ID_OR_NULL },
> +          PTR_TO_BTF_ID_OR_NULL | PTR_TRUSTED },

Alexei, what do you think about having "PTR_MAYBE_NULL | PTR_TRUSTED" here?
The verifier side looks fine (eg. is_trusted_reg() is taking PTR_MAYBE_NULL into 
consideration). However, it seems this will be the first "PTR_MAYBE_NULL | 
PTR_TRUSTED" use case and not sure if PTR_MAYBE_NULL may conceptually conflict 
with the PTR_TRUSTED idea (like PTR_TRUSTED should not be NULL).

>       },
>       .get_func_proto        = bpf_iter_tcp_get_func_proto,
>       .seq_info        = &tcp_seq_info,
> diff --git i/net/ipv4/udp.c w/net/ipv4/udp.c
> index 746c85f2bb03..945b641b363b 100644
> --- i/net/ipv4/udp.c
> +++ w/net/ipv4/udp.c
> @@ -3646,7 +3646,7 @@ static struct bpf_iter_reg udp_reg_info = {
>       .ctx_arg_info_size    = 1,
>       .ctx_arg_info        = {
>           { offsetof(struct bpf_iter__udp, udp_sk),
> -          PTR_TO_BTF_ID_OR_NULL },
> +          PTR_TO_BTF_ID_OR_NULL | PTR_TRUSTED },
>       },
>       .seq_info        = &udp_seq_info,
>   };

Re: [PATCH v7 bpf-next 06/10] bpf: Add bpf_sock_destroy kfunc

[Alexei Starovoitov]

On Fri, May 5, 2023 at 11:49 AM Martin KaFai Lau <martin.lau@linux.dev> wrote:
>
> On 5/4/23 5:13 PM, Martin KaFai Lau wrote:
> >
> > Follow up on the v6 patch-set regarding KF_TRUSTED_ARGS.
> > KF_TRUSTED_ARGS is needed here to avoid the cases where a PTR_TO_BTF_ID sk is
> > obtained by following another pointer. eg. getting a sk pointer (may be even
> > NULL) by following another sk pointer. The recent PTR_TRUSTED concept in the
> > verifier can guard this. I tried and the following should do:
> >
> > diff --git i/net/core/filter.c w/net/core/filter.c
> > index 68b228f3eca6..d82e038da0e3 100644
> > --- i/net/core/filter.c
> > +++ w/net/core/filter.c
> > @@ -11767,7 +11767,7 @@ __bpf_kfunc int bpf_sock_destroy(struct sock_common *sock)
> >   __diag_pop()
> >
> >   BTF_SET8_START(sock_destroy_kfunc_set)
> > -BTF_ID_FLAGS(func, bpf_sock_destroy)
> > +BTF_ID_FLAGS(func, bpf_sock_destroy, KF_TRUSTED_ARGS)
> >   BTF_SET8_END(sock_destroy_kfunc_set)
> >
> >   static int tracing_iter_filter(const struct bpf_prog *prog, u32 kfunc_id)
> > diff --git i/net/ipv4/tcp_ipv4.c w/net/ipv4/tcp_ipv4.c
> > index 887f83a90d85..a769284e8291 100644
> > --- i/net/ipv4/tcp_ipv4.c
> > +++ w/net/ipv4/tcp_ipv4.c
> > @@ -3354,7 +3354,7 @@ static struct bpf_iter_reg tcp_reg_info = {
> >       .ctx_arg_info_size    = 1,
> >       .ctx_arg_info        = {
> >           { offsetof(struct bpf_iter__tcp, sk_common),
> > -          PTR_TO_BTF_ID_OR_NULL },
> > +          PTR_TO_BTF_ID_OR_NULL | PTR_TRUSTED },
>
> Alexei, what do you think about having "PTR_MAYBE_NULL | PTR_TRUSTED" here?
> The verifier side looks fine (eg. is_trusted_reg() is taking PTR_MAYBE_NULL into
> consideration). However, it seems this will be the first "PTR_MAYBE_NULL |
> PTR_TRUSTED" use case and not sure if PTR_MAYBE_NULL may conceptually conflict
> with the PTR_TRUSTED idea (like PTR_TRUSTED should not be NULL).

Conceptually it should be fine. There are no real cases of
PTR_TRUSTED | PTR_MAYBE_NULL now, though check_reg_type() handles it.
Proceed with care, I guess :)