Commit f371c923 authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

Merge branch 'csum-fixes' 



Daniel Borkmann says:

====================
This series fixes an issue originally reported by Lorenz Bauer where using
the bpf_skb_adjust_room() helper hid a checksum bug since it wasn't adjusting
CHECKSUM_UNNECESSARY's skb->csum_level after decap. The fix is two-fold:
 i) We do a safe reset in bpf_skb_adjust_room() to CHECKSUM_NONE with an opt-
    out flag BPF_F_ADJ_ROOM_NO_CSUM_RESET.
ii) We add a new bpf_csum_level() for the latter in order to allow users to
    manually inc/dec the skb->csum_level when needed.
The series is rebased against latest bpf-next tree. It can be applied there,
or to bpf after the merge win sync from net-next.

Thanks!
====================

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents 9a25c1df c4ba153b

include/linux/skbuff.h

+8 −0
Original line number Diff line number Diff line
@@ -3919,6 +3919,14 @@ static inline void __skb_incr_checksum_unnecessary(struct sk_buff *skb) 
	}

}



static inline void __skb_reset_checksum_unnecessary(struct sk_buff *skb)

{

	if (skb->ip_summed == CHECKSUM_UNNECESSARY) {

		skb->ip_summed = CHECKSUM_NONE;

		skb->csum_level = 0;

	}

}



/* Check if we need to perform checksum complete validation.

 *

 * Returns true if checksum complete is needed, false otherwise

include/uapi/linux/bpf.h

+50 −1
Original line number Diff line number Diff line
@@ -1635,6 +1635,13 @@ union bpf_attr { 
 * 		Grow or shrink the room for data in the packet associated to

 * 		*skb* by *len_diff*, and according to the selected *mode*.

 *

 * 		By default, the helper will reset any offloaded checksum

 * 		indicator of the skb to CHECKSUM_NONE. This can be avoided

 * 		by the following flag:

 *

 * 		* **BPF_F_ADJ_ROOM_NO_CSUM_RESET**: Do not reset offloaded

 * 		  checksum data of the skb to CHECKSUM_NONE.

 *

 *		There are two supported modes at this time:

 *

 *		* **BPF_ADJ_ROOM_MAC**: Adjust room at the mac layer
@@ -3213,6 +3220,38 @@ union bpf_attr { 
 *		calculation.

 *	Return

 *		Requested value, or 0, if flags are not recognized.

 *

 * int bpf_csum_level(struct sk_buff *skb, u64 level)

 * 	Description

 * 		Change the skbs checksum level by one layer up or down, or

 * 		reset it entirely to none in order to have the stack perform

 * 		checksum validation. The level is applicable to the following

 * 		protocols: TCP, UDP, GRE, SCTP, FCOE. For example, a decap of

 * 		| ETH | IP | UDP | GUE | IP | TCP | into | ETH | IP | TCP |

 * 		through **bpf_skb_adjust_room**\ () helper with passing in

 * 		**BPF_F_ADJ_ROOM_NO_CSUM_RESET** flag would require one	call

 * 		to **bpf_csum_level**\ () with **BPF_CSUM_LEVEL_DEC** since

 * 		the UDP header is removed. Similarly, an encap of the latter

 * 		into the former could be accompanied by a helper call to

 * 		**bpf_csum_level**\ () with **BPF_CSUM_LEVEL_INC** if the

 * 		skb is still intended to be processed in higher layers of the

 * 		stack instead of just egressing at tc.

 *

 * 		There are three supported level settings at this time:

 *

 * 		* **BPF_CSUM_LEVEL_INC**: Increases skb->csum_level for skbs

 * 		  with CHECKSUM_UNNECESSARY.

 * 		* **BPF_CSUM_LEVEL_DEC**: Decreases skb->csum_level for skbs

 * 		  with CHECKSUM_UNNECESSARY.

 * 		* **BPF_CSUM_LEVEL_RESET**: Resets skb->csum_level to 0 and

 * 		  sets CHECKSUM_NONE to force checksum validation by the stack.

 * 		* **BPF_CSUM_LEVEL_QUERY**: No-op, returns the current

 * 		  skb->csum_level.

 * 	Return

 * 		0 on success, or a negative error in case of failure. In the

 * 		case of **BPF_CSUM_LEVEL_QUERY**, the current skb->csum_level

 * 		is returned or the error code -EACCES in case the skb is not

 * 		subject to CHECKSUM_UNNECESSARY.

 */

#define __BPF_FUNC_MAPPER(FN)		\

	FN(unspec),			\
@@ -3349,7 +3388,8 @@ union bpf_attr { 
	FN(ringbuf_reserve),		\

	FN(ringbuf_submit),		\

	FN(ringbuf_discard),		\

	FN(ringbuf_query),

	FN(ringbuf_query),		\

	FN(csum_level),



/* integer value in 'imm' field of BPF_CALL instruction selects which helper

 * function eBPF program intends to call
@@ -3426,6 +3466,14 @@ enum { 
	BPF_F_CURRENT_NETNS		= (-1L),

};



/* BPF_FUNC_csum_level level values. */

enum {

	BPF_CSUM_LEVEL_QUERY,

	BPF_CSUM_LEVEL_INC,

	BPF_CSUM_LEVEL_DEC,

	BPF_CSUM_LEVEL_RESET,

};



/* BPF_FUNC_skb_adjust_room flags. */

enum {

	BPF_F_ADJ_ROOM_FIXED_GSO	= (1ULL << 0),
@@ -3433,6 +3481,7 @@ enum { 
	BPF_F_ADJ_ROOM_ENCAP_L3_IPV6	= (1ULL << 2),

	BPF_F_ADJ_ROOM_ENCAP_L4_GRE	= (1ULL << 3),

	BPF_F_ADJ_ROOM_ENCAP_L4_UDP	= (1ULL << 4),

	BPF_F_ADJ_ROOM_NO_CSUM_RESET	= (1ULL << 5),

};



enum {

net/core/filter.c

+44 −2
Original line number Diff line number Diff line
@@ -2015,6 +2015,40 @@ static const struct bpf_func_proto bpf_csum_update_proto = { 
	.arg2_type	= ARG_ANYTHING,

};



BPF_CALL_2(bpf_csum_level, struct sk_buff *, skb, u64, level)

{

	/* The interface is to be used in combination with bpf_skb_adjust_room()

	 * for encap/decap of packet headers when BPF_F_ADJ_ROOM_NO_CSUM_RESET

	 * is passed as flags, for example.

	 */

	switch (level) {

	case BPF_CSUM_LEVEL_INC:

		__skb_incr_checksum_unnecessary(skb);

		break;

	case BPF_CSUM_LEVEL_DEC:

		__skb_decr_checksum_unnecessary(skb);

		break;

	case BPF_CSUM_LEVEL_RESET:

		__skb_reset_checksum_unnecessary(skb);

		break;

	case BPF_CSUM_LEVEL_QUERY:

		return skb->ip_summed == CHECKSUM_UNNECESSARY ?

		       skb->csum_level : -EACCES;

	default:

		return -EINVAL;

	}



	return 0;

}



static const struct bpf_func_proto bpf_csum_level_proto = {

	.func		= bpf_csum_level,

	.gpl_only	= false,

	.ret_type	= RET_INTEGER,

	.arg1_type	= ARG_PTR_TO_CTX,

	.arg2_type	= ARG_ANYTHING,

};



static inline int __bpf_rx_skb(struct net_device *dev, struct sk_buff *skb)

{

	return dev_forward_skb(dev, skb);
@@ -3113,7 +3147,8 @@ static int bpf_skb_net_shrink(struct sk_buff *skb, u32 off, u32 len_diff, 
{

	int ret;



	if (flags & ~BPF_F_ADJ_ROOM_FIXED_GSO)

	if (unlikely(flags & ~(BPF_F_ADJ_ROOM_FIXED_GSO |

			       BPF_F_ADJ_ROOM_NO_CSUM_RESET)))

		return -EINVAL;



	if (skb_is_gso(skb) && !skb_is_gso_tcp(skb)) {
@@ -3163,7 +3198,8 @@ BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff, 
	u32 off;

	int ret;



	if (unlikely(flags & ~BPF_F_ADJ_ROOM_MASK))

	if (unlikely(flags & ~(BPF_F_ADJ_ROOM_MASK |

			       BPF_F_ADJ_ROOM_NO_CSUM_RESET)))

		return -EINVAL;

	if (unlikely(len_diff_abs > 0xfffU))

		return -EFAULT;
@@ -3191,6 +3227,8 @@ BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff, 


	ret = shrink ? bpf_skb_net_shrink(skb, off, len_diff_abs, flags) :

		       bpf_skb_net_grow(skb, off, len_diff_abs, flags);

	if (!ret && !(flags & BPF_F_ADJ_ROOM_NO_CSUM_RESET))

		__skb_reset_checksum_unnecessary(skb);



	bpf_compute_data_pointers(skb);

	return ret;
@@ -6276,6 +6314,8 @@ tc_cls_act_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) 
		return &bpf_csum_diff_proto;

	case BPF_FUNC_csum_update:

		return &bpf_csum_update_proto;

	case BPF_FUNC_csum_level:

		return &bpf_csum_level_proto;

	case BPF_FUNC_l3_csum_replace:

		return &bpf_l3_csum_replace_proto;

	case BPF_FUNC_l4_csum_replace:
@@ -6609,6 +6649,8 @@ lwt_xmit_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) 
		return &bpf_skb_store_bytes_proto;

	case BPF_FUNC_csum_update:

		return &bpf_csum_update_proto;

	case BPF_FUNC_csum_level:

		return &bpf_csum_level_proto;

	case BPF_FUNC_l3_csum_replace:

		return &bpf_l3_csum_replace_proto;

	case BPF_FUNC_l4_csum_replace:

tools/include/uapi/linux/bpf.h

+50 −1
Original line number Diff line number Diff line
@@ -1635,6 +1635,13 @@ union bpf_attr { 
 * 		Grow or shrink the room for data in the packet associated to

 * 		*skb* by *len_diff*, and according to the selected *mode*.

 *

 * 		By default, the helper will reset any offloaded checksum

 * 		indicator of the skb to CHECKSUM_NONE. This can be avoided

 * 		by the following flag:

 *

 * 		* **BPF_F_ADJ_ROOM_NO_CSUM_RESET**: Do not reset offloaded

 * 		  checksum data of the skb to CHECKSUM_NONE.

 *

 *		There are two supported modes at this time:

 *

 *		* **BPF_ADJ_ROOM_MAC**: Adjust room at the mac layer
@@ -3213,6 +3220,38 @@ union bpf_attr { 
 *		calculation.

 *	Return

 *		Requested value, or 0, if flags are not recognized.

 *

 * int bpf_csum_level(struct sk_buff *skb, u64 level)

 * 	Description

 * 		Change the skbs checksum level by one layer up or down, or

 * 		reset it entirely to none in order to have the stack perform

 * 		checksum validation. The level is applicable to the following

 * 		protocols: TCP, UDP, GRE, SCTP, FCOE. For example, a decap of

 * 		| ETH | IP | UDP | GUE | IP | TCP | into | ETH | IP | TCP |

 * 		through **bpf_skb_adjust_room**\ () helper with passing in

 * 		**BPF_F_ADJ_ROOM_NO_CSUM_RESET** flag would require one	call

 * 		to **bpf_csum_level**\ () with **BPF_CSUM_LEVEL_DEC** since

 * 		the UDP header is removed. Similarly, an encap of the latter

 * 		into the former could be accompanied by a helper call to

 * 		**bpf_csum_level**\ () with **BPF_CSUM_LEVEL_INC** if the

 * 		skb is still intended to be processed in higher layers of the

 * 		stack instead of just egressing at tc.

 *

 * 		There are three supported level settings at this time:

 *

 * 		* **BPF_CSUM_LEVEL_INC**: Increases skb->csum_level for skbs

 * 		  with CHECKSUM_UNNECESSARY.

 * 		* **BPF_CSUM_LEVEL_DEC**: Decreases skb->csum_level for skbs

 * 		  with CHECKSUM_UNNECESSARY.

 * 		* **BPF_CSUM_LEVEL_RESET**: Resets skb->csum_level to 0 and

 * 		  sets CHECKSUM_NONE to force checksum validation by the stack.

 * 		* **BPF_CSUM_LEVEL_QUERY**: No-op, returns the current

 * 		  skb->csum_level.

 * 	Return

 * 		0 on success, or a negative error in case of failure. In the

 * 		case of **BPF_CSUM_LEVEL_QUERY**, the current skb->csum_level

 * 		is returned or the error code -EACCES in case the skb is not

 * 		subject to CHECKSUM_UNNECESSARY.

 */

#define __BPF_FUNC_MAPPER(FN)		\

	FN(unspec),			\
@@ -3349,7 +3388,8 @@ union bpf_attr { 
	FN(ringbuf_reserve),		\

	FN(ringbuf_submit),		\

	FN(ringbuf_discard),		\

	FN(ringbuf_query),

	FN(ringbuf_query),		\

	FN(csum_level),



/* integer value in 'imm' field of BPF_CALL instruction selects which helper

 * function eBPF program intends to call
@@ -3426,6 +3466,14 @@ enum { 
	BPF_F_CURRENT_NETNS		= (-1L),

};



/* BPF_FUNC_csum_level level values. */

enum {

	BPF_CSUM_LEVEL_QUERY,

	BPF_CSUM_LEVEL_INC,

	BPF_CSUM_LEVEL_DEC,

	BPF_CSUM_LEVEL_RESET,

};



/* BPF_FUNC_skb_adjust_room flags. */

enum {

	BPF_F_ADJ_ROOM_FIXED_GSO	= (1ULL << 0),
@@ -3433,6 +3481,7 @@ enum { 
	BPF_F_ADJ_ROOM_ENCAP_L3_IPV6	= (1ULL << 2),

	BPF_F_ADJ_ROOM_ENCAP_L4_GRE	= (1ULL << 3),

	BPF_F_ADJ_ROOM_ENCAP_L4_UDP	= (1ULL << 4),

	BPF_F_ADJ_ROOM_NO_CSUM_RESET	= (1ULL << 5),

};



enum {

tools/testing/selftests/bpf/progs/test_cls_redirect.c

+6 −3
Original line number Diff line number Diff line
@@ -380,9 +380,10 @@ static ret_t accept_locally(struct __sk_buff *skb, encap_headers_t *encap) 
	}



	if (bpf_skb_adjust_room(skb, -encap_overhead, BPF_ADJ_ROOM_MAC,

				BPF_F_ADJ_ROOM_FIXED_GSO)) {

				BPF_F_ADJ_ROOM_FIXED_GSO |

				BPF_F_ADJ_ROOM_NO_CSUM_RESET) ||

	    bpf_csum_level(skb, BPF_CSUM_LEVEL_DEC))

		return TC_ACT_SHOT;

	}



	return bpf_redirect(skb->ifindex, BPF_F_INGRESS);

}
@@ -472,7 +473,9 @@ static ret_t forward_with_gre(struct __sk_buff *skb, encap_headers_t *encap, 
	}



	if (bpf_skb_adjust_room(skb, delta, BPF_ADJ_ROOM_NET,

				BPF_F_ADJ_ROOM_FIXED_GSO)) {

				BPF_F_ADJ_ROOM_FIXED_GSO |

				BPF_F_ADJ_ROOM_NO_CSUM_RESET) ||

	    bpf_csum_level(skb, BPF_CSUM_LEVEL_INC)) {

		metrics->errors_total_encap_adjust_failed++;

		return TC_ACT_SHOT;

	}

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