Commit 074f528e authored by Daniel Borkmann's avatar Daniel Borkmann Committed by David S. Miller
Browse files

bpf: convert relevant helper args to ARG_PTR_TO_RAW_STACK 



This patch converts all helpers that can use ARG_PTR_TO_RAW_STACK as argument
type. For tc programs this is bpf_skb_load_bytes(), bpf_skb_get_tunnel_key(),
bpf_skb_get_tunnel_opt(). For tracing, this optimizes bpf_get_current_comm()
and bpf_probe_read(). The check in bpf_skb_load_bytes() for MAX_BPF_STACK can
also be removed since the verifier already makes sure we stay within bounds
on stack buffers.

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 435faee1

kernel/bpf/helpers.c

+13 −4
Original line number Diff line number Diff line
@@ -163,17 +163,26 @@ static u64 bpf_get_current_comm(u64 r1, u64 size, u64 r3, u64 r4, u64 r5) 
	struct task_struct *task = current;

	char *buf = (char *) (long) r1;



	if (!task)

		return -EINVAL;

	if (unlikely(!task))

		goto err_clear;



	strncpy(buf, task->comm, size);



	strlcpy(buf, task->comm, min_t(size_t, size, sizeof(task->comm)));

	/* Verifier guarantees that size > 0. For task->comm exceeding

	 * size, guarantee that buf is %NUL-terminated. Unconditionally

	 * done here to save the size test.

	 */

	buf[size - 1] = 0;

	return 0;

err_clear:

	memset(buf, 0, size);

	return -EINVAL;

}



const struct bpf_func_proto bpf_get_current_comm_proto = {

	.func		= bpf_get_current_comm,

	.gpl_only	= false,

	.ret_type	= RET_INTEGER,

	.arg1_type	= ARG_PTR_TO_STACK,

	.arg1_type	= ARG_PTR_TO_RAW_STACK,

	.arg2_type	= ARG_CONST_STACK_SIZE,

};

kernel/trace/bpf_trace.c

+7 −3
Original line number Diff line number Diff line
@@ -62,17 +62,21 @@ EXPORT_SYMBOL_GPL(trace_call_bpf); 
static u64 bpf_probe_read(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)

{

	void *dst = (void *) (long) r1;

	int size = (int) r2;

	int ret, size = (int) r2;

	void *unsafe_ptr = (void *) (long) r3;



	return probe_kernel_read(dst, unsafe_ptr, size);

	ret = probe_kernel_read(dst, unsafe_ptr, size);

	if (unlikely(ret < 0))

		memset(dst, 0, size);



	return ret;

}



static const struct bpf_func_proto bpf_probe_read_proto = {

	.func		= bpf_probe_read,

	.gpl_only	= true,

	.ret_type	= RET_INTEGER,

	.arg1_type	= ARG_PTR_TO_STACK,

	.arg1_type	= ARG_PTR_TO_RAW_STACK,

	.arg2_type	= ARG_CONST_STACK_SIZE,

	.arg3_type	= ARG_ANYTHING,

};

net/core/filter.c

+40 −17
Original line number Diff line number Diff line
@@ -1409,16 +1409,19 @@ static u64 bpf_skb_load_bytes(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) 
	unsigned int len = (unsigned int) r4;

	void *ptr;



	if (unlikely((u32) offset > 0xffff || len > MAX_BPF_STACK))

		return -EFAULT;

	if (unlikely((u32) offset > 0xffff))

		goto err_clear;



	ptr = skb_header_pointer(skb, offset, len, to);

	if (unlikely(!ptr))

		return -EFAULT;

		goto err_clear;

	if (ptr != to)

		memcpy(to, ptr, len);



	return 0;

err_clear:

	memset(to, 0, len);

	return -EFAULT;

}



static const struct bpf_func_proto bpf_skb_load_bytes_proto = {
@@ -1427,7 +1430,7 @@ static const struct bpf_func_proto bpf_skb_load_bytes_proto = { 
	.ret_type	= RET_INTEGER,

	.arg1_type	= ARG_PTR_TO_CTX,

	.arg2_type	= ARG_ANYTHING,

	.arg3_type	= ARG_PTR_TO_STACK,

	.arg3_type	= ARG_PTR_TO_RAW_STACK,

	.arg4_type	= ARG_CONST_STACK_SIZE,

};
@@ -1756,12 +1759,19 @@ static u64 bpf_skb_get_tunnel_key(u64 r1, u64 r2, u64 size, u64 flags, u64 r5) 
	struct bpf_tunnel_key *to = (struct bpf_tunnel_key *) (long) r2;

	const struct ip_tunnel_info *info = skb_tunnel_info(skb);

	u8 compat[sizeof(struct bpf_tunnel_key)];

	void *to_orig = to;

	int err;



	if (unlikely(!info || (flags & ~(BPF_F_TUNINFO_IPV6))))

		return -EINVAL;

	if (ip_tunnel_info_af(info) != bpf_tunnel_key_af(flags))

		return -EPROTO;

	if (unlikely(!info || (flags & ~(BPF_F_TUNINFO_IPV6)))) {

		err = -EINVAL;

		goto err_clear;

	}

	if (ip_tunnel_info_af(info) != bpf_tunnel_key_af(flags)) {

		err = -EPROTO;

		goto err_clear;

	}

	if (unlikely(size != sizeof(struct bpf_tunnel_key))) {

		err = -EINVAL;

		switch (size) {

		case offsetof(struct bpf_tunnel_key, tunnel_label):

		case offsetof(struct bpf_tunnel_key, tunnel_ext):
@@ -1771,12 +1781,12 @@ static u64 bpf_skb_get_tunnel_key(u64 r1, u64 r2, u64 size, u64 flags, u64 r5) 
			 * a common path later on.

			 */

			if (ip_tunnel_info_af(info) != AF_INET)

				return -EINVAL;

				goto err_clear;

set_compat:

			to = (struct bpf_tunnel_key *)compat;

			break;

		default:

			return -EINVAL;

			goto err_clear;

		}

	}
@@ -1793,9 +1803,12 @@ set_compat: 
	}



	if (unlikely(size != sizeof(struct bpf_tunnel_key)))

		memcpy((void *)(long) r2, to, size);

		memcpy(to_orig, to, size);



	return 0;

err_clear:

	memset(to_orig, 0, size);

	return err;

}



static const struct bpf_func_proto bpf_skb_get_tunnel_key_proto = {
@@ -1803,7 +1816,7 @@ static const struct bpf_func_proto bpf_skb_get_tunnel_key_proto = { 
	.gpl_only	= false,

	.ret_type	= RET_INTEGER,

	.arg1_type	= ARG_PTR_TO_CTX,

	.arg2_type	= ARG_PTR_TO_STACK,

	.arg2_type	= ARG_PTR_TO_RAW_STACK,

	.arg3_type	= ARG_CONST_STACK_SIZE,

	.arg4_type	= ARG_ANYTHING,

};
@@ -1813,16 +1826,26 @@ static u64 bpf_skb_get_tunnel_opt(u64 r1, u64 r2, u64 size, u64 r4, u64 r5) 
	struct sk_buff *skb = (struct sk_buff *) (long) r1;

	u8 *to = (u8 *) (long) r2;

	const struct ip_tunnel_info *info = skb_tunnel_info(skb);

	int err;



	if (unlikely(!info ||

		     !(info->key.tun_flags & TUNNEL_OPTIONS_PRESENT)))

		return -ENOENT;

	if (unlikely(size < info->options_len))

		return -ENOMEM;

		     !(info->key.tun_flags & TUNNEL_OPTIONS_PRESENT))) {

		err = -ENOENT;

		goto err_clear;

	}

	if (unlikely(size < info->options_len)) {

		err = -ENOMEM;

		goto err_clear;

	}



	ip_tunnel_info_opts_get(to, info);

	if (size > info->options_len)

		memset(to + info->options_len, 0, size - info->options_len);



	return info->options_len;

err_clear:

	memset(to, 0, size);

	return err;

}



static const struct bpf_func_proto bpf_skb_get_tunnel_opt_proto = {
@@ -1830,7 +1853,7 @@ static const struct bpf_func_proto bpf_skb_get_tunnel_opt_proto = { 
	.gpl_only	= false,

	.ret_type	= RET_INTEGER,

	.arg1_type	= ARG_PTR_TO_CTX,

	.arg2_type	= ARG_PTR_TO_STACK,

	.arg2_type	= ARG_PTR_TO_RAW_STACK,

	.arg3_type	= ARG_CONST_STACK_SIZE,

};

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