bpf: sockmap sample test for bpf_msg_pull_data

This adds an option to test the msg_pull_data helper. This
uses two options txmsg_start and txmsg_end to let the user
specify start and end bytes to pull.

The options can be used with txmsg_apply, txmsg_cork options
as well as with any of the basic tests, txmsg, txmsg_redir and
txmsg_drop (plus noisy variants) to run pull_data inline with
those tests. By giving user direct control over the variables
we can easily do negative testing as well as positive tests.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

samples/sockmap/sockmap_kern.c

@@ -71,6 +71,14 @@ struct bpf_map_def SEC("maps") sock_cork_bytes = {
 	.max_entries = 1
 };
 
+struct bpf_map_def SEC("maps") sock_pull_bytes = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(int),
+	.value_size = sizeof(int),
+	.max_entries = 2
+};
+
+
 SEC("sk_skb1")
 int bpf_prog1(struct __sk_buff *skb)
 {
@@ -137,7 +145,8 @@ int bpf_sockmap(struct bpf_sock_ops *skops)
 SEC("sk_msg1")
 int bpf_prog4(struct sk_msg_md *msg)
 {
-	int *bytes, zero = 0;
+	int *bytes, zero = 0, one = 1;
+	int *start, *end;
 
 	bytes = bpf_map_lookup_elem(&sock_apply_bytes, &zero);
 	if (bytes)
@@ -145,15 +154,18 @@ int bpf_prog4(struct sk_msg_md *msg)
 	bytes = bpf_map_lookup_elem(&sock_cork_bytes, &zero);
 	if (bytes)
 		bpf_msg_cork_bytes(msg, *bytes);
+	start = bpf_map_lookup_elem(&sock_pull_bytes, &zero);
+	end = bpf_map_lookup_elem(&sock_pull_bytes, &one);
+	if (start && end)
+		bpf_msg_pull_data(msg, *start, *end, 0);
 	return SK_PASS;
 }
 
 SEC("sk_msg2")
 int bpf_prog5(struct sk_msg_md *msg)
 {
-	void *data_end = (void *)(long) msg->data_end;
-	void *data = (void *)(long) msg->data;
-	int *bytes, err1 = -1, err2 = -1, zero = 0;
+	int err1 = -1, err2 = -1, zero = 0, one = 1;
+	int *bytes, *start, *end, len1, len2;
 
 	bytes = bpf_map_lookup_elem(&sock_apply_bytes, &zero);
 	if (bytes)
@@ -161,17 +173,32 @@ int bpf_prog5(struct sk_msg_md *msg)
 	bytes = bpf_map_lookup_elem(&sock_cork_bytes, &zero);
 	if (bytes)
 		err2 = bpf_msg_cork_bytes(msg, *bytes);
+	len1 = (__u64)msg->data_end - (__u64)msg->data;
+	start = bpf_map_lookup_elem(&sock_pull_bytes, &zero);
+	end = bpf_map_lookup_elem(&sock_pull_bytes, &one);
+	if (start && end) {
+		int err;
+
+		bpf_printk("sk_msg2: pull(%i:%i)\n",
+			   start ? *start : 0, end ? *end : 0);
+		err = bpf_msg_pull_data(msg, *start, *end, 0);
+		if (err)
+			bpf_printk("sk_msg2: pull_data err %i\n",
+				   err);
+		len2 = (__u64)msg->data_end - (__u64)msg->data;
+		bpf_printk("sk_msg2: length update %i->%i\n",
+			   len1, len2);
+	}
 	bpf_printk("sk_msg2: data length %i err1 %i err2 %i\n",
-		   (__u64)data_end - (__u64)data, err1, err2);
+		   len1, err1, err2);
 	return SK_PASS;
 }
 
 SEC("sk_msg3")
 int bpf_prog6(struct sk_msg_md *msg)
 {
-	void *data_end = (void *)(long) msg->data_end;
-	void *data = (void *)(long) msg->data;
-	int *bytes, zero = 0;
+	int *bytes, zero = 0, one = 1;
+	int *start, *end;
 
 	bytes = bpf_map_lookup_elem(&sock_apply_bytes, &zero);
 	if (bytes)
@@ -179,15 +206,18 @@ int bpf_prog6(struct sk_msg_md *msg)
 	bytes = bpf_map_lookup_elem(&sock_cork_bytes, &zero);
 	if (bytes)
 		bpf_msg_cork_bytes(msg, *bytes);
+	start = bpf_map_lookup_elem(&sock_pull_bytes, &zero);
+	end = bpf_map_lookup_elem(&sock_pull_bytes, &one);
+	if (start && end)
+		bpf_msg_pull_data(msg, *start, *end, 0);
 	return bpf_msg_redirect_map(msg, &sock_map_redir, zero, 0);
 }
 
 SEC("sk_msg4")
 int bpf_prog7(struct sk_msg_md *msg)
 {
-	void *data_end = (void *)(long) msg->data_end;
-	void *data = (void *)(long) msg->data;
-	int *bytes, err1 = 0, err2 = 0, zero = 0;
+	int err1 = 0, err2 = 0, zero = 0, one = 1;
+	int *bytes, *start, *end, len1, len2;
 
 	bytes = bpf_map_lookup_elem(&sock_apply_bytes, &zero);
 	if (bytes)
@@ -195,9 +225,24 @@ int bpf_prog7(struct sk_msg_md *msg)
 	bytes = bpf_map_lookup_elem(&sock_cork_bytes, &zero);
 	if (bytes)
 		err2 = bpf_msg_cork_bytes(msg, *bytes);
-
+	len1 = (__u64)msg->data_end - (__u64)msg->data;
+	start = bpf_map_lookup_elem(&sock_pull_bytes, &zero);
+	end = bpf_map_lookup_elem(&sock_pull_bytes, &one);
+	if (start && end) {
+		int err;
+
+		bpf_printk("sk_msg2: pull(%i:%i)\n",
+			   start ? *start : 0, end ? *end : 0);
+		err = bpf_msg_pull_data(msg, *start, *end, 0);
+		if (err)
+			bpf_printk("sk_msg2: pull_data err %i\n",
+				   err);
+		len2 = (__u64)msg->data_end - (__u64)msg->data;
+		bpf_printk("sk_msg2: length update %i->%i\n",
+			   len1, len2);
+	}
 	bpf_printk("sk_msg3: redirect(%iB) err1=%i err2=%i\n",
-		   (__u64)data_end - (__u64)data, err1, err2);
+		   len1, err1, err2);
 	return bpf_msg_redirect_map(msg, &sock_map_redir, zero, 0);
 }
 
@@ -239,7 +284,8 @@ int bpf_prog9(struct sk_msg_md *msg)
 SEC("sk_msg7")
 int bpf_prog10(struct sk_msg_md *msg)
 {
-	int *bytes, zero = 0;
+	int *bytes, zero = 0, one = 1;
+	int *start, *end;
 
 	bytes = bpf_map_lookup_elem(&sock_apply_bytes, &zero);
 	if (bytes)
@@ -247,6 +293,11 @@ int bpf_prog10(struct sk_msg_md *msg)
 	bytes = bpf_map_lookup_elem(&sock_cork_bytes, &zero);
 	if (bytes)
 		bpf_msg_cork_bytes(msg, *bytes);
+	start = bpf_map_lookup_elem(&sock_pull_bytes, &zero);
+	end = bpf_map_lookup_elem(&sock_pull_bytes, &one);
+	if (start && end)
+		bpf_msg_pull_data(msg, *start, *end, 0);
+
 	return SK_DROP;
 }
 

samples/sockmap/sockmap_user.c

@@ -62,6 +62,8 @@ int txmsg_redir_noisy;
 int txmsg_drop;
 int txmsg_apply;
 int txmsg_cork;
+int txmsg_start;
+int txmsg_end;
 
 static const struct option long_options[] = {
 	{"help",	no_argument,		NULL, 'h' },
@@ -79,6 +81,8 @@ static const struct option long_options[] = {
 	{"txmsg_drop",		no_argument,	&txmsg_drop, 1 },
 	{"txmsg_apply",	required_argument,	NULL, 'a'},
 	{"txmsg_cork",	required_argument,	NULL, 'k'},
+	{"txmsg_start", required_argument,	NULL, 's'},
+	{"txmsg_end",	required_argument,	NULL, 'e'},
 	{0, 0, NULL, 0 }
 };
 
@@ -572,6 +576,12 @@ int main(int argc, char **argv)
 	while ((opt = getopt_long(argc, argv, ":dhvc:r:i:l:t:",
 				  long_options, &longindex)) != -1) {
 		switch (opt) {
+		case 's':
+			txmsg_start = atoi(optarg);
+			break;
+		case 'e':
+			txmsg_end = atoi(optarg);
+			break;
 		case 'a':
 			txmsg_apply = atoi(optarg);
 			break;
@@ -761,6 +771,28 @@ run:
 			}
 		}
 
+		if (txmsg_start) {
+			err = bpf_map_update_elem(map_fd[5],
+						  &i, &txmsg_start, BPF_ANY);
+			if (err) {
+				fprintf(stderr,
+					"ERROR: bpf_map_update_elem (txmsg_start):  %d (%s)\n",
+					err, strerror(errno));
+				return err;
+			}
+		}
+
+		if (txmsg_end) {
+			i = 1;
+			err = bpf_map_update_elem(map_fd[5],
+						  &i, &txmsg_end, BPF_ANY);
+			if (err) {
+				fprintf(stderr,
+					"ERROR: bpf_map_update_elem (txmsg_end):  %d (%s)\n",
+					err, strerror(errno));
+				return err;
+			}
+		}
 	}
 
 	if (txmsg_drop)

tools/include/uapi/linux/bpf.h

@@ -793,7 +793,8 @@ union bpf_attr {
 	FN(sock_ops_cb_flags_set),	\
 	FN(msg_redirect_map),		\
 	FN(msg_apply_bytes),		\
-	FN(msg_cork_bytes),
+	FN(msg_cork_bytes),		\
+	FN(msg_pull_data),
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
  * function eBPF program intends to call

tools/testing/selftests/bpf/bpf_helpers.h

@@ -92,6 +92,8 @@ static int (*bpf_msg_apply_bytes)(void *ctx, int len) =
 	(void *) BPF_FUNC_msg_apply_bytes;
 static int (*bpf_msg_cork_bytes)(void *ctx, int len) =
 	(void *) BPF_FUNC_msg_cork_bytes;
+static int (*bpf_msg_pull_data)(void *ctx, int start, int end, int flags) =
+	(void *) BPF_FUNC_msg_pull_data;
 
 /* llvm builtin functions that eBPF C program may use to
  * emit BPF_LD_ABS and BPF_LD_IND instructions