Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Daniel Borkmann says:

====================
pull-request: bpf 2024-01-18

We've added 10 non-merge commits during the last 5 day(s) which contain
a total of 12 files changed, 806 insertions(+), 51 deletions(-).

The main changes are:

1) Fix an issue in bpf_iter_udp under backward progress which prevents
   user space process from finishing iteration, from Martin KaFai Lau.

2) Fix BPF verifier to reject variable offset alu on registers with a type
   of PTR_TO_FLOW_KEYS to prevent oob access, from Hao Sun.

3) Follow up fixes for kernel- and libbpf-side logic around handling
   arg:ctx tagged arguments of BPF global subprogs, from Andrii Nakryiko.

* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
  libbpf: warn on unexpected __arg_ctx type when rewriting BTF
  selftests/bpf: add tests confirming type logic in kernel for __arg_ctx
  bpf: enforce types for __arg_ctx-tagged arguments in global subprogs
  bpf: extract bpf_ctx_convert_map logic and make it more reusable
  libbpf: feature-detect arg:ctx tag support in kernel
  selftests/bpf: Add test for alu on PTR_TO_FLOW_KEYS
  bpf: Reject variable offset alu on PTR_TO_FLOW_KEYS
  selftests/bpf: Test udp and tcp iter batching
  bpf: Avoid iter->offset making backward progress in bpf_iter_udp
  bpf: iter_udp: Retry with a larger batch size without going back to the previous bucket
====================

Link: https://lore.kernel.org/r/20240118153936.11769-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 10 insertions, 12 deletions

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 5f742d0b9e07..148ffb007969 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -3137,16 +3137,18 @@ 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);
+	int resume_bucket, resume_offset;
 	struct udp_table *udptable;
 	unsigned int batch_sks = 0;
 	bool resized = false;
 	struct sock *sk;
 
+	resume_bucket = state->bucket;
+	resume_offset = iter->offset;
+
 	/* The current batch is done, so advance the bucket. */
-	if (iter->st_bucket_done) {
+	if (iter->st_bucket_done)
 		state->bucket++;
-		iter->offset = 0;
-	}
 
 	udptable = udp_get_table_seq(seq, net);
 
@@ -3166,19 +3168,19 @@ again:
 	for (; state->bucket <= udptable->mask; state->bucket++) {
 		struct udp_hslot *hslot2 = &udptable->hash2[state->bucket];
 
-		if (hlist_empty(&hslot2->head)) {
-			iter->offset = 0;
+		if (hlist_empty(&hslot2->head))
 			continue;
-		}
 
+		iter->offset = 0;
 		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;
+				if (state->bucket == resume_bucket &&
+				    iter->offset < resume_offset) {
+					++iter->offset;
 					continue;
 				}
 				if (iter->end_sk < iter->max_sk) {
@@ -3192,9 +3194,6 @@ again:
 
 		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. */
@@ -3213,7 +3212,6 @@ again:
 		/* After allocating a larger batch, retry one more time to grab
 		 * the whole bucket.
 		 */
-		state->bucket--;
 		goto again;
 	}
 done: