From 69e5cce40775feb75db992e7aec02f26f1897eac Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 27 Aug 2020 15:01:12 -0700 Subject: [PATCH] UPSTREAM: bpf: Add bpf_copy_from_user() helper. Sleepable BPF programs can now use copy_from_user() to access user memory. Change-Id: Ifaf2da741d14dc56b121163d7c486e5c15d1d5a4 Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Acked-by: KP Singh Link: https://lore.kernel.org/bpf/20200827220114.69225-4-alexei.starovoitov@gmail.com --- include/linux/bpf.h | 1 + include/uapi/linux/bpf.h | 8 ++++++++ kernel/bpf/helpers.c | 22 ++++++++++++++++++++++ kernel/trace/bpf_trace.c | 2 ++ tools/include/uapi/linux/bpf.h | 8 ++++++++ 5 files changed, 41 insertions(+) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index a0cb8cff56e2..66cb81de600c 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1803,6 +1803,7 @@ 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); diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 603f38f29e43..555c3f397974 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -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 diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index d1081c3ef6de..928428ea9158 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -611,6 +611,28 @@ 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; diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 16e94edc319a..882b5757c322 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1152,6 +1152,8 @@ 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; } diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 2f1833b61d2c..b6ca9b346539 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -3502,6 +3502,13 @@ 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), \ @@ -3652,6 +3659,7 @@ 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