Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit f035a515 authored by Daniel Borkmann's avatar Daniel Borkmann Committed by David S. Miller
Browse files

bpf: add BPF_SIZEOF and BPF_FIELD_SIZEOF macros 



Add BPF_SIZEOF() and BPF_FIELD_SIZEOF() macros to improve the code a bit
which otherwise often result in overly long bytes_to_bpf_size(sizeof())
and bytes_to_bpf_size(FIELD_SIZEOF()) lines. So place them into a macro
helper instead. Moreover, we currently have a BUILD_BUG_ON(BPF_FIELD_SIZEOF())
check in convert_bpf_extensions(), but we should rather make that generic
as well and add a BUILD_BUG_ON() test in all BPF_SIZEOF()/BPF_FIELD_SIZEOF()
users to detect any rewriter size issues at compile time. Note, there are
currently none, but we want to assert that it stays this way.

Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6088b582

include/linux/filter.h

+14 −0
Original line number Diff line number Diff line
@@ -314,6 +314,20 @@ struct bpf_prog_aux; 
	bpf_size;						\

})



#define BPF_SIZEOF(type)					\

	({							\

		const int __size = bytes_to_bpf_size(sizeof(type)); \

		BUILD_BUG_ON(__size < 0);			\

		__size;						\

	})



#define BPF_FIELD_SIZEOF(type, field)				\

	({							\

		const int __size = bytes_to_bpf_size(FIELD_SIZEOF(type, field)); \

		BUILD_BUG_ON(__size < 0);			\

		__size;						\

	})



#ifdef CONFIG_COMPAT

/* A struct sock_filter is architecture independent. */

struct compat_sock_fprog {

kernel/trace/bpf_trace.c

+6 −6
Original line number Diff line number Diff line
@@ -583,18 +583,18 @@ static u32 pe_prog_convert_ctx_access(enum bpf_access_type type, int dst_reg, 
	switch (ctx_off) {

	case offsetof(struct bpf_perf_event_data, sample_period):

		BUILD_BUG_ON(FIELD_SIZEOF(struct perf_sample_data, period) != sizeof(u64));

		*insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct bpf_perf_event_data_kern, data)),

				      dst_reg, src_reg,



		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern,

						       data), dst_reg, src_reg,

				      offsetof(struct bpf_perf_event_data_kern, data));

		*insn++ = BPF_LDX_MEM(BPF_DW, dst_reg, dst_reg,

				      offsetof(struct perf_sample_data, period));

		break;

	default:

		*insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct bpf_perf_event_data_kern, regs)),

				      dst_reg, src_reg,

		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct bpf_perf_event_data_kern,

						       regs), dst_reg, src_reg,

				      offsetof(struct bpf_perf_event_data_kern, regs));

		*insn++ = BPF_LDX_MEM(bytes_to_bpf_size(sizeof(long)),

				      dst_reg, dst_reg, ctx_off);

		*insn++ = BPF_LDX_MEM(BPF_SIZEOF(long), dst_reg, dst_reg, ctx_off);

		break;

	}

net/core/filter.c

+7 −8
Original line number Diff line number Diff line
@@ -233,9 +233,8 @@ static bool convert_bpf_extensions(struct sock_filter *fp, 
	case SKF_AD_OFF + SKF_AD_HATYPE:

		BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);

		BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, type) != 2);

		BUILD_BUG_ON(bytes_to_bpf_size(FIELD_SIZEOF(struct sk_buff, dev)) < 0);



		*insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct sk_buff, dev)),

		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, dev),

				      BPF_REG_TMP, BPF_REG_CTX,

				      offsetof(struct sk_buff, dev));

		/* if (tmp != 0) goto pc + 1 */
@@ -2685,7 +2684,7 @@ static u32 bpf_net_convert_ctx_access(enum bpf_access_type type, int dst_reg, 
	case offsetof(struct __sk_buff, ifindex):

		BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);



		*insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct sk_buff, dev)),

		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, dev),

				      dst_reg, src_reg,

				      offsetof(struct sk_buff, dev));

		*insn++ = BPF_JMP_IMM(BPF_JEQ, dst_reg, 0, 1);
@@ -2750,7 +2749,7 @@ static u32 bpf_net_convert_ctx_access(enum bpf_access_type type, int dst_reg, 
		break;



	case offsetof(struct __sk_buff, data):

		*insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct sk_buff, data)),

		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, data),

				      dst_reg, src_reg,

				      offsetof(struct sk_buff, data));

		break;
@@ -2759,8 +2758,8 @@ static u32 bpf_net_convert_ctx_access(enum bpf_access_type type, int dst_reg, 
		ctx_off -= offsetof(struct __sk_buff, data_end);

		ctx_off += offsetof(struct sk_buff, cb);

		ctx_off += offsetof(struct bpf_skb_data_end, data_end);

		*insn++ = BPF_LDX_MEM(bytes_to_bpf_size(sizeof(void *)),

				      dst_reg, src_reg, ctx_off);

		*insn++ = BPF_LDX_MEM(BPF_SIZEOF(void *), dst_reg, src_reg,

				      ctx_off);

		break;



	case offsetof(struct __sk_buff, tc_index):
@@ -2795,12 +2794,12 @@ static u32 xdp_convert_ctx_access(enum bpf_access_type type, int dst_reg, 


	switch (ctx_off) {

	case offsetof(struct xdp_md, data):

		*insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct xdp_buff, data)),

		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct xdp_buff, data),

				      dst_reg, src_reg,

				      offsetof(struct xdp_buff, data));

		break;

	case offsetof(struct xdp_md, data_end):

		*insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct xdp_buff, data_end)),

		*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct xdp_buff, data_end),

				      dst_reg, src_reg,

				      offsetof(struct xdp_buff, data_end));

		break;