ARM: net: handle negative offsets in BPF JIT. (6d715e30) · Commits · 戴 / test

arch/arm/net/bpf_jit_32.c

+38 −9

Original line number	Diff line number	Diff line
		@@ -74,31 +74,51 @@ struct jit_ctx {

		int bpf_jit_enable __read_mostly;

		static u64 jit_get_skb_b(struct sk_buff *skb, unsigned offset)
		static inline int call_neg_helper(struct sk_buff skb, int offset, void ret,
		unsigned int size)
		{
		void *ptr = bpf_internal_load_pointer_neg_helper(skb, offset, size);

		if (!ptr)
		return -EFAULT;
		memcpy(ret, ptr, size);
		return 0;
		}

		static u64 jit_get_skb_b(struct sk_buff *skb, int offset)
		{
		u8 ret;
		int err;

		if (offset < 0)
		err = call_neg_helper(skb, offset, &ret, 1);
		else
		err = skb_copy_bits(skb, offset, &ret, 1);

		return (u64)err << 32 \| ret;
		}

		static u64 jit_get_skb_h(struct sk_buff *skb, unsigned offset)
		static u64 jit_get_skb_h(struct sk_buff *skb, int offset)
		{
		u16 ret;
		int err;

		if (offset < 0)
		err = call_neg_helper(skb, offset, &ret, 2);
		else
		err = skb_copy_bits(skb, offset, &ret, 2);

		return (u64)err << 32 \| ntohs(ret);
		}

		static u64 jit_get_skb_w(struct sk_buff *skb, unsigned offset)
		static u64 jit_get_skb_w(struct sk_buff *skb, int offset)
		{
		u32 ret;
		int err;

		if (offset < 0)
		err = call_neg_helper(skb, offset, &ret, 4);
		else
		err = skb_copy_bits(skb, offset, &ret, 4);

		return (u64)err << 32 \| ntohl(ret);
		@@ -536,9 +556,6 @@ static int build_body(struct jit_ctx *ctx)
		case BPF_LD \| BPF_B \| BPF_ABS:
		load_order = 0;
		load:
		/* the interpreter will deal with the negative K */
		if ((int)k < 0)
		return -ENOTSUPP;
		emit_mov_i(r_off, k, ctx);
		load_common:
		ctx->seen \|= SEEN_DATA \| SEEN_CALL;
		@@ -553,6 +570,18 @@ load_common:
		condt = ARM_COND_HI;
		}

		/*
		* test for negative offset, only if we are
		* currently scheduled to take the fast
		* path. this will update the flags so that
		* the slowpath instruction are ignored if the
		* offset is negative.
		*
		* for loard_order == 0 the HI condition will
		* make loads at offset 0 take the slow path too.
		*/
		_emit(condt, ARM_CMP_I(r_off, 0), ctx);

		_emit(condt, ARM_ADD_R(r_scratch, r_off, r_skb_data),
		ctx);

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