[bpf-next PATCH v3 15/18] bpf: sockmap sample support for bpf_msg_cork_bytes()

John Fastabend
2018-03-18T19:58:06Z

Add sample application support for the bpf_msg_cork_bytes helper. This
lets the user specify how many bytes each verdict should apply to.

Similar to apply_bytes() tests these can be run as a stand-alone test
when used without other options or inline with other tests by using
the txmsg_cork option along with any of the basic tests txmsg,
txmsg_redir, txmsg_drop.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
---
samples/sockmap/sockmap_kern.c | 53 +++++++++++++++++++++++++----
samples/sockmap/sockmap_user.c | 19 ++++++++++
tools/include/uapi/linux/bpf.h | 3 +-
tools/testing/selftests/bpf/bpf_helpers.h | 2 +
4 files changed, 68 insertions(+), 9 deletions(-)

diff --git a/samples/sockmap/sockmap_kern.c b/samples/sockmap/sockmap_kern.c
index 205ec36..7352267 100644
--- a/samples/sockmap/sockmap_kern.c
+++ b/samples/sockmap/sockmap_kern.c
@@ -64,6 +64,13 @@ struct bpf_map_def SEC("maps") sock_apply_bytes = {
.max_entries = 1
};

+struct bpf_map_def SEC("maps") sock_cork_bytes = {
+ .type = BPF_MAP_TYPE_ARRAY,
+ .key_size = sizeof(int),
+ .value_size = sizeof(int),
+ .max_entries = 1
+};
+
SEC("sk_skb1")
int bpf_prog1(struct __sk_buff *skb)
{
@@ -135,6 +142,9 @@ int bpf_prog4(struct sk_msg_md *msg)
bytes = bpf_map_lookup_elem(&sock_apply_bytes, &zero);
if (bytes)
bpf_msg_apply_bytes(msg, *bytes);
+ bytes = bpf_map_lookup_elem(&sock_cork_bytes, &zero);
+ if (bytes)
+ bpf_msg_cork_bytes(msg, *bytes);
return SK_PASS;
}

@@ -143,13 +153,16 @@ int bpf_prog5(struct sk_msg_md *msg)
{
void *data_end = (void *)(long) msg->data_end;
void *data = (void *)(long) msg->data;
- int *bytes, err = 0, zero = 0;
+ int *bytes, err1 = -1, err2 = -1, zero = 0;

bytes = bpf_map_lookup_elem(&sock_apply_bytes, &zero);
if (bytes)
- err = bpf_msg_apply_bytes(msg, *bytes);
- bpf_printk("sk_msg2: data length %i err %i\n",
- (__u64)data_end - (__u64)data, err);
+ err1 = bpf_msg_apply_bytes(msg, *bytes);
+ bytes = bpf_map_lookup_elem(&sock_cork_bytes, &zero);
+ if (bytes)
+ err2 = bpf_msg_cork_bytes(msg, *bytes);
+ bpf_printk("sk_msg2: data length %i err1 %i err2 %i\n",
+ (__u64)data_end - (__u64)data, err1, err2);
return SK_PASS;
}

@@ -163,6 +176,9 @@ int bpf_prog6(struct sk_msg_md *msg)
bytes = bpf_map_lookup_elem(&sock_apply_bytes, &zero);
if (bytes)
bpf_msg_apply_bytes(msg, *bytes);
+ bytes = bpf_map_lookup_elem(&sock_cork_bytes, &zero);
+ if (bytes)
+ bpf_msg_cork_bytes(msg, *bytes);
return bpf_msg_redirect_map(msg, &sock_map_redir, zero, 0);
}

@@ -171,13 +187,17 @@ int bpf_prog7(struct sk_msg_md *msg)
{
void *data_end = (void *)(long) msg->data_end;
void *data = (void *)(long) msg->data;
- int *bytes, err = 0, zero = 0;
+ int *bytes, err1 = 0, err2 = 0, zero = 0;

bytes = bpf_map_lookup_elem(&sock_apply_bytes, &zero);
if (bytes)
- err = bpf_msg_apply_bytes(msg, *bytes);
- bpf_printk("sk_msg3: redirect(%iB) err=%i\n",
- (__u64)data_end - (__u64)data, err);
+ err1 = bpf_msg_apply_bytes(msg, *bytes);
+ bytes = bpf_map_lookup_elem(&sock_cork_bytes, &zero);
+ if (bytes)
+ err2 = bpf_msg_cork_bytes(msg, *bytes);
+
+ bpf_printk("sk_msg3: redirect(%iB) err1=%i err2=%i\n",
+ (__u64)data_end - (__u64)data, err1, err2);
return bpf_msg_redirect_map(msg, &sock_map_redir, zero, 0);
}

@@ -198,5 +218,22 @@ int bpf_prog8(struct sk_msg_md *msg)
}
return SK_PASS;
}
+SEC("sk_msg6")
+int bpf_prog9(struct sk_msg_md *msg)
+{
+ void *data_end = (void *)(long) msg->data_end;
+ void *data = (void *)(long) msg->data;
+ int ret = 0, *bytes, zero = 0;
+
+ bytes = bpf_map_lookup_elem(&sock_cork_bytes, &zero);
+ if (bytes) {
+ if (((__u64)data_end - (__u64)data) >= *bytes)
+ return SK_PASS;
+ ret = bpf_msg_cork_bytes(msg, *bytes);
+ if (ret)
+ return SK_DROP;
+ }
+ return SK_PASS;
+}

char _license[] SEC("license") = "GPL";
diff --git a/samples/sockmap/sockmap_user.c b/samples/sockmap/sockmap_user.c
index 41774ec..4e0a3d8 100644
--- a/samples/sockmap/sockmap_user.c
+++ b/samples/sockmap/sockmap_user.c
@@ -60,6 +60,7 @@
int txmsg_redir;
int txmsg_redir_noisy;
int txmsg_apply;
+int txmsg_cork;

static const struct option long_options[] = {
{"help", no_argument, NULL, 'h' },
@@ -75,6 +76,7 @@
{"txmsg_redir", no_argument, &txmsg_redir, 1 },
{"txmsg_redir_noisy", no_argument, &txmsg_redir_noisy, 1},
{"txmsg_apply", required_argument, NULL, 'a'},
+ {"txmsg_cork", required_argument, NULL, 'k'},
{0, 0, NULL, 0 }
};

@@ -551,6 +553,9 @@ int main(int argc, char **argv)
case 'a':
txmsg_apply = atoi(optarg);
break;
+ case 'k':
+ txmsg_cork = atoi(optarg);
+ break;
case 'c':
cg_fd = open(optarg, O_DIRECTORY, O_RDONLY);
if (cg_fd < 0) {
@@ -671,6 +676,8 @@ int main(int argc, char **argv)
tx_prog_fd = prog_fd[6];
else if (txmsg_apply)
tx_prog_fd = prog_fd[7];
+ else if (txmsg_cork)
+ tx_prog_fd = prog_fd[8];
else
tx_prog_fd = 0;

@@ -716,6 +723,18 @@ int main(int argc, char **argv)
return err;
}
}
+
+ if (txmsg_cork) {
+ err = bpf_map_update_elem(map_fd[4],
+ &i, &txmsg_cork, BPF_ANY);
+ if (err) {
+ fprintf(stderr,
+ "ERROR: bpf_map_update_elem (cork_bytes): %d (%s\n",
+ err, strerror(errno));
+ return err;
+ }
+ }
+
}
if (test == PING_PONG)
err = forever_ping_pong(rate, &options);
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 01b9c97..e6924ab 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -792,7 +792,8 @@ struct bpf_stack_build_id {
FN(override_return), \
FN(sock_ops_cb_flags_set), \
FN(msg_redirect_map), \
- FN(msg_apply_bytes),
+ FN(msg_apply_bytes), \
+ FN(msg_cork_bytes),

/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call
diff --git a/tools/testing/selftests/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
index 4713de4..b5b45ff 100644
--- a/tools/testing/selftests/bpf/bpf_helpers.h
+++ b/tools/testing/selftests/bpf/bpf_helpers.h
@@ -90,6 +90,8 @@ static int (*bpf_msg_redirect_map)(void *ctx, void *map, int key, int flags) =
(void *) BPF_FUNC_msg_redirect_map;
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;

/* llvm builtin functions that eBPF C program may use to
* emit BPF_LD_ABS and BPF_LD_IND instructions