Merge branch 'Add skb_adjust_room() for SK_SKB'

John Fastabend says:

====================
This implements the helper skb_adjust_room() for BPF_SKS_SK_STREAM_VERDICT
programs so we can push/pop headers from the data on recieve. One use
case is to pop TLS headers off kTLS packets.

The first patch implements the helper and the second updates test_sockmap
to use it removing some case handling we had to do earlier to account for
the TLS headers in the kTLS tests.

v1->v2:
 Fix error path for TLS case (Daniel)
 check mode input is 0 because we don't use it now (Daniel)
 Remove incorrect/misleading comment (Lorenz)

Thanks,
John
Acked-by: Martin KaFai Lau <kafai@fb.com>
---
====================

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

2 files changed, 31 insertions, 30 deletions

diff --git a/tools/testing/selftests/bpf/progs/test_sockmap_kern.h b/tools/testing/selftests/bpf/progs/test_sockmap_kern.h
index 3dca4c2e2418..1858435de7aa 100644
--- a/tools/testing/selftests/bpf/progs/test_sockmap_kern.h
+++ b/tools/testing/selftests/bpf/progs/test_sockmap_kern.h
@@ -131,39 +131,55 @@ int bpf_prog2(struct __sk_buff *skb)
 
 }
 
-SEC("sk_skb3")
-int bpf_prog3(struct __sk_buff *skb)
+static inline void bpf_write_pass(struct __sk_buff *skb, int offset)
 {
-	const int one = 1;
-	int err, *f, ret = SK_PASS;
+	int err = bpf_skb_pull_data(skb, 6 + offset);
 	void *data_end;
 	char *c;
 
-	err = bpf_skb_pull_data(skb, 19);
 	if (err)
-		goto tls_out;
+		return;
 
 	c = (char *)(long)skb->data;
 	data_end = (void *)(long)skb->data_end;
 
-	if (c + 18 < data_end)
-		memcpy(&c[13], "PASS", 4);
+	if (c + 5 + offset < data_end)
+		memcpy(c + offset, "PASS", 4);
+}
+
+SEC("sk_skb3")
+int bpf_prog3(struct __sk_buff *skb)
+{
+	int err, *f, ret = SK_PASS;
+	const int one = 1;
+
 	f = bpf_map_lookup_elem(&sock_skb_opts, &one);
 	if (f && *f) {
 		__u64 flags = 0;
 
 		ret = 0;
 		flags = *f;
+
+		err = bpf_skb_adjust_room(skb, -13, 0, 0);
+		if (err)
+			return SK_DROP;
+		err = bpf_skb_adjust_room(skb, 4, 0, 0);
+		if (err)
+			return SK_DROP;
+		bpf_write_pass(skb, 0);
 #ifdef SOCKMAP
 		return bpf_sk_redirect_map(skb, &tls_sock_map, ret, flags);
 #else
 		return bpf_sk_redirect_hash(skb, &tls_sock_map, &ret, flags);
 #endif
 	}
-
 	f = bpf_map_lookup_elem(&sock_skb_opts, &one);
 	if (f && *f)
 		ret = SK_DROP;
+	err = bpf_skb_adjust_room(skb, 4, 0, 0);
+	if (err)
+		return SK_DROP;
+	bpf_write_pass(skb, 13);
 tls_out:
 	return ret;
 }
diff --git a/tools/testing/selftests/bpf/test_sockmap.c b/tools/testing/selftests/bpf/test_sockmap.c
index 9b6fb00dc7a0..5cf45455de42 100644
--- a/tools/testing/selftests/bpf/test_sockmap.c
+++ b/tools/testing/selftests/bpf/test_sockmap.c
@@ -518,28 +518,13 @@ static int msg_verify_data(struct msghdr *msg, int size, int chunk_sz)
 		if (i == 0 && txmsg_ktls_skb) {
 			if (msg->msg_iov[i].iov_len < 4)
 				return -EIO;
-			if (txmsg_ktls_skb_redir) {
-				if (memcmp(&d[13], "PASS", 4) != 0) {
-					fprintf(stderr,
-						"detected redirect ktls_skb data error with skb ingress update @iov[%i]:%i \"%02x %02x %02x %02x\" != \"PASS\"\n", i, 0, d[13], d[14], d[15], d[16]);
-					return -EIO;
-				}
-				d[13] = 0;
-				d[14] = 1;
-				d[15] = 2;
-				d[16] = 3;
-				j = 13;
-			} else if (txmsg_ktls_skb) {
-				if (memcmp(d, "PASS", 4) != 0) {
-					fprintf(stderr,
-						"detected ktls_skb data error with skb ingress update @iov[%i]:%i \"%02x %02x %02x %02x\" != \"PASS\"\n", i, 0, d[0], d[1], d[2], d[3]);
-					return -EIO;
-				}
-				d[0] = 0;
-				d[1] = 1;
-				d[2] = 2;
-				d[3] = 3;
+			if (memcmp(d, "PASS", 4) != 0) {
+				fprintf(stderr,
+					"detected skb data error with skb ingress update @iov[%i]:%i \"%02x %02x %02x %02x\" != \"PASS\"\n",
+					i, 0, d[0], d[1], d[2], d[3]);
+				return -EIO;
 			}
+			j = 4; /* advance index past PASS header */
 		}
 
 		for (; j < msg->msg_iov[i].iov_len && size; j++) {