bpf: Factor btf_struct_access function (1c6d28a6) · Commits · 戴 / test

kernel/bpf/btf.c

+65 −10

Original line number	Diff line number	Diff line
		@@ -3886,16 +3886,22 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type,
		return true;
		}

		int btf_struct_access(struct bpf_verifier_log *log,
		enum bpf_struct_walk_result {
		/* < 0 error */
		WALK_SCALAR = 0,
		WALK_PTR,
		WALK_STRUCT,
		};

		static int btf_struct_walk(struct bpf_verifier_log *log,
		const struct btf_type *t, int off, int size,
		enum bpf_access_type atype,
		u32 *next_btf_id)
		{
		u32 i, moff, mtrue_end, msize = 0, total_nelems = 0;
		const struct btf_type mtype, elem_type = NULL;
		const struct btf_member *member;
		const char tname, mname;
		u32 vlen;
		u32 vlen, elem_id, mid;

		again:
		tname = __btf_name_by_offset(btf_vmlinux, t->name_off);
		@@ -3966,7 +3972,7 @@ error:
		*/
		if (off <= moff &&
		BITS_ROUNDUP_BYTES(end_bit) <= off + size)
		return SCALAR_VALUE;
		return WALK_SCALAR;

		/* off may be accessing a following member
		*
		@@ -3988,11 +3994,13 @@ error:
		break;

		/* type of the field */
		mid = member->type;
		mtype = btf_type_by_id(btf_vmlinux, member->type);
		mname = __btf_name_by_offset(btf_vmlinux, member->name_off);

		mtype = __btf_resolve_size(btf_vmlinux, mtype, &msize,
		&elem_type, NULL, &total_nelems, NULL);
		&elem_type, &elem_id, &total_nelems,
		&mid);
		if (IS_ERR(mtype)) {
		bpf_log(log, "field %s doesn't have size\n", mname);
		return -EFAULT;
		@@ -4054,6 +4062,7 @@ error:
		elem_idx = (off - moff) / msize;
		moff += elem_idx * msize;
		mtype = elem_type;
		mid = elem_id;
		}

		/* the 'off' we're looking for is either equal to start
		@@ -4063,6 +4072,12 @@ error:
		/* our field must be inside that union or struct */
		t = mtype;

		/* return if the offset matches the member offset */
		if (off == moff) {
		*next_btf_id = mid;
		return WALK_STRUCT;
		}

		/* adjust offset we're looking for */
		off -= moff;
		goto again;
		@@ -4078,11 +4093,10 @@ error:
		mname, moff, tname, off, size);
		return -EACCES;
		}

		stype = btf_type_skip_modifiers(btf_vmlinux, mtype->type, &id);
		if (btf_type_is_struct(stype)) {
		*next_btf_id = id;
		return PTR_TO_BTF_ID;
		return WALK_PTR;
		}
		}

		@@ -4099,12 +4113,53 @@ error:
		return -EACCES;
		}

		return SCALAR_VALUE;
		return WALK_SCALAR;
		}
		bpf_log(log, "struct %s doesn't have field at offset %d\n", tname, off);
		return -EINVAL;
		}

		int btf_struct_access(struct bpf_verifier_log *log,
		const struct btf_type *t, int off, int size,
		enum bpf_access_type atype __maybe_unused,
		u32 *next_btf_id)
		{
		int err;
		u32 id;

		do {
		err = btf_struct_walk(log, t, off, size, &id);

		switch (err) {
		case WALK_PTR:
		/* If we found the pointer or scalar on t+off,
		* we're done.
		*/
		*next_btf_id = id;
		return PTR_TO_BTF_ID;
		case WALK_SCALAR:
		return SCALAR_VALUE;
		case WALK_STRUCT:
		/* We found nested struct, so continue the search
		* by diving in it. At this point the offset is
		* aligned with the new type, so set it to 0.
		*/
		t = btf_type_by_id(btf_vmlinux, id);
		off = 0;
		break;
		default:
		/* It's either error or unknown return value..
		* scream and leave.
		*/
		if (WARN_ONCE(err > 0, "unknown btf_struct_walk return value"))
		return -EINVAL;
		return err;
		}
		} while (t);

		return -EINVAL;
		}

		int btf_resolve_helper_id(struct bpf_verifier_log *log,
		const struct bpf_func_proto *fn, int arg)
		{

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