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bpf: Add bpf_copy_from_user() helper.

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

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: KP Singh <kpsingh@google.com>
Link: https://lore.kernel.org/bpf/20200827220114.69225-4-alexei.starovoitov@gmail.com
This commit is contained in:
Alexei Starovoitov 2020-08-27 15:01:12 -07:00 committed by Daniel Borkmann
parent 1e6c62a882
commit 07be4c4a3e
5 changed files with 41 additions and 0 deletions
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1
include/linux/bpf.h
View File

@ -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);

8
include/uapi/linux/bpf.h
View File

@ -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

22
kernel/bpf/helpers.c
View File

@ -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;

2
kernel/trace/bpf_trace.c
View File

@ -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;
}

8
tools/include/uapi/linux/bpf.h
View File

@ -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