Commit 07be4c4a authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by Daniel Borkmann
Browse files

bpf: Add bpf_copy_from_user() helper. 



Sleepable BPF programs can now use copy_from_user() to access user memory.

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Acked-by: default avatarKP Singh <kpsingh@google.com>
Link: https://lore.kernel.org/bpf/20200827220114.69225-4-alexei.starovoitov@gmail.com
parent 1e6c62a8

include/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -1784,6 +1784,7 @@ extern const struct bpf_func_proto bpf_skc_to_tcp_sock_proto; 
extern const struct bpf_func_proto bpf_skc_to_tcp_timewait_sock_proto;

extern const struct bpf_func_proto bpf_skc_to_tcp_request_sock_proto;

extern const struct bpf_func_proto bpf_skc_to_udp6_sock_proto;

extern const struct bpf_func_proto bpf_copy_from_user_proto;



const struct bpf_func_proto *bpf_tracing_func_proto(

	enum bpf_func_id func_id, const struct bpf_prog *prog);

include/uapi/linux/bpf.h

+8 −0
Original line number Diff line number Diff line
@@ -3569,6 +3569,13 @@ union bpf_attr { 
 *		On success, the strictly positive length of the string,

 *		including the trailing NUL character. On error, a negative

 *		value.

 *

 * long bpf_copy_from_user(void *dst, u32 size, const void *user_ptr)

 * 	Description

 * 		Read *size* bytes from user space address *user_ptr* and store

 * 		the data in *dst*. This is a wrapper of copy_from_user().

 * 	Return

 * 		0 on success, or a negative error in case of failure.

 */

#define __BPF_FUNC_MAPPER(FN)		\

	FN(unspec),			\
@@ -3719,6 +3726,7 @@ union bpf_attr { 
	FN(inode_storage_get),		\

	FN(inode_storage_delete),	\

	FN(d_path),			\

	FN(copy_from_user),		\

	/* */



/* integer value in 'imm' field of BPF_CALL instruction selects which helper

kernel/bpf/helpers.c

+22 −0
Original line number Diff line number Diff line
@@ -601,6 +601,28 @@ const struct bpf_func_proto bpf_event_output_data_proto = { 
	.arg5_type      = ARG_CONST_SIZE_OR_ZERO,

};



BPF_CALL_3(bpf_copy_from_user, void *, dst, u32, size,

	   const void __user *, user_ptr)

{

	int ret = copy_from_user(dst, user_ptr, size);



	if (unlikely(ret)) {

		memset(dst, 0, size);

		ret = -EFAULT;

	}



	return ret;

}



const struct bpf_func_proto bpf_copy_from_user_proto = {

	.func		= bpf_copy_from_user,

	.gpl_only	= false,

	.ret_type	= RET_INTEGER,

	.arg1_type	= ARG_PTR_TO_UNINIT_MEM,

	.arg2_type	= ARG_CONST_SIZE_OR_ZERO,

	.arg3_type	= ARG_ANYTHING,

};



const struct bpf_func_proto bpf_get_current_task_proto __weak;

const struct bpf_func_proto bpf_probe_read_user_proto __weak;

const struct bpf_func_proto bpf_probe_read_user_str_proto __weak;

kernel/trace/bpf_trace.c

+2 −0
Original line number Diff line number Diff line
@@ -1228,6 +1228,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) 
		return &bpf_jiffies64_proto;

	case BPF_FUNC_get_task_stack:

		return &bpf_get_task_stack_proto;

	case BPF_FUNC_copy_from_user:

		return prog->aux->sleepable ? &bpf_copy_from_user_proto : NULL;

	default:

		return NULL;

	}

tools/include/uapi/linux/bpf.h

+8 −0
Original line number Diff line number Diff line
@@ -3569,6 +3569,13 @@ union bpf_attr { 
 *		On success, the strictly positive length of the string,

 *		including the trailing NUL character. On error, a negative

 *		value.

 *

 * long bpf_copy_from_user(void *dst, u32 size, const void *user_ptr)

 * 	Description

 * 		Read *size* bytes from user space address *user_ptr* and store

 * 		the data in *dst*. This is a wrapper of copy_from_user().

 * 	Return

 * 		0 on success, or a negative error in case of failure.

 */

#define __BPF_FUNC_MAPPER(FN)		\

	FN(unspec),			\
@@ -3719,6 +3726,7 @@ union bpf_attr { 
	FN(inode_storage_get),		\

	FN(inode_storage_delete),	\

	FN(d_path),			\

	FN(copy_from_user),		\

	/* */



/* integer value in 'imm' field of BPF_CALL instruction selects which helper

CRA Git | Maintained and supported by SUSTech CRA and CCSE