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Commit ea2e7ce5 authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by David S. Miller
Browse files

bpf: support 8-byte metafield access 



The verifier supported only 4-byte metafields in
struct __sk_buff and struct xdp_md. The metafields in upcoming
struct bpf_perf_event are 8-byte to match register width in struct pt_regs.
Teach verifier to recognize 8-byte metafield access.
The patch doesn't affect safety of sockets and xdp programs.
They check for 4-byte only ctx access before these conditions are hit.

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 569e937e

kernel/bpf/verifier.c

+6 −3
Original line number Diff line number Diff line
@@ -2333,7 +2333,8 @@ static int do_check(struct verifier_env *env) 
			if (err)

				return err;



			if (BPF_SIZE(insn->code) != BPF_W) {

			if (BPF_SIZE(insn->code) != BPF_W &&

			    BPF_SIZE(insn->code) != BPF_DW) {

				insn_idx++;

				continue;

			}
@@ -2642,9 +2643,11 @@ static int convert_ctx_accesses(struct verifier_env *env) 
	for (i = 0; i < insn_cnt; i++, insn++) {

		u32 insn_delta, cnt;



		if (insn->code == (BPF_LDX | BPF_MEM | BPF_W))

		if (insn->code == (BPF_LDX | BPF_MEM | BPF_W) ||

		    insn->code == (BPF_LDX | BPF_MEM | BPF_DW))

			type = BPF_READ;

		else if (insn->code == (BPF_STX | BPF_MEM | BPF_W))

		else if (insn->code == (BPF_STX | BPF_MEM | BPF_W) ||

			 insn->code == (BPF_STX | BPF_MEM | BPF_DW))

			type = BPF_WRITE;

		else

			continue;