Commit fb91db01 authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

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: default avatarMartin KaFai Lau <kafai@fb.com>
---
====================

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents 60a128b5 91274ca5

net/core/filter.c

+46 −0
Original line number Diff line number Diff line
@@ -76,6 +76,7 @@ 
#include <net/bpf_sk_storage.h>

#include <net/transp_v6.h>

#include <linux/btf_ids.h>

#include <net/tls.h>



static const struct bpf_func_proto *

bpf_sk_base_func_proto(enum bpf_func_id func_id);
@@ -3479,6 +3480,48 @@ static u32 __bpf_skb_max_len(const struct sk_buff *skb) 
			  SKB_MAX_ALLOC;

}



BPF_CALL_4(sk_skb_adjust_room, struct sk_buff *, skb, s32, len_diff,

	   u32, mode, u64, flags)

{

	u32 len_diff_abs = abs(len_diff);

	bool shrink = len_diff < 0;

	int ret = 0;



	if (unlikely(flags || mode))

		return -EINVAL;

	if (unlikely(len_diff_abs > 0xfffU))

		return -EFAULT;



	if (!shrink) {

		ret = skb_cow(skb, len_diff);

		if (unlikely(ret < 0))

			return ret;

		__skb_push(skb, len_diff_abs);

		memset(skb->data, 0, len_diff_abs);

	} else {

		if (unlikely(!pskb_may_pull(skb, len_diff_abs)))

			return -ENOMEM;

		__skb_pull(skb, len_diff_abs);

	}

	bpf_compute_data_end_sk_skb(skb);

	if (tls_sw_has_ctx_rx(skb->sk)) {

		struct strp_msg *rxm = strp_msg(skb);



		rxm->full_len += len_diff;

	}

	return ret;

}



static const struct bpf_func_proto sk_skb_adjust_room_proto = {

	.func		= sk_skb_adjust_room,

	.gpl_only	= false,

	.ret_type	= RET_INTEGER,

	.arg1_type	= ARG_PTR_TO_CTX,

	.arg2_type	= ARG_ANYTHING,

	.arg3_type	= ARG_ANYTHING,

	.arg4_type	= ARG_ANYTHING,

};



BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff,

	   u32, mode, u64, flags)

{
@@ -6745,6 +6788,7 @@ bool bpf_helper_changes_pkt_data(void *func) 
	    func == bpf_skb_change_tail ||

	    func == sk_skb_change_tail ||

	    func == bpf_skb_adjust_room ||

	    func == sk_skb_adjust_room ||

	    func == bpf_skb_pull_data ||

	    func == sk_skb_pull_data ||

	    func == bpf_clone_redirect ||
@@ -7218,6 +7262,8 @@ sk_skb_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) 
		return &sk_skb_change_tail_proto;

	case BPF_FUNC_skb_change_head:

		return &sk_skb_change_head_proto;

	case BPF_FUNC_skb_adjust_room:

		return &sk_skb_adjust_room_proto;

	case BPF_FUNC_get_socket_cookie:

		return &bpf_get_socket_cookie_proto;

	case BPF_FUNC_get_socket_uid:

tools/testing/selftests/bpf/progs/test_sockmap_kern.h

+25 −9
Original line number Diff line number Diff line
@@ -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;

}

tools/testing/selftests/bpf/test_sockmap.c

+6 −21
Original line number Diff line number Diff line
@@ -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]);

					"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;

			}

				d[0] = 0;

				d[1] = 1;

				d[2] = 2;

				d[3] = 3;

			}

			j = 4; /* advance index past PASS header */

		}



		for (; j < msg->msg_iov[i].iov_len && size; j++) {