Commit df86ca0d authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Daniel Borkmann
Browse files

bpf: Allow attach TRACING programs through LINK_CREATE command 



Allow attaching BTF-aware TRACING programs, previously attachable only
through BPF_RAW_TRACEPOINT_OPEN command, through LINK_CREATE command:

  - BTF-aware raw tracepoints (tp_btf in libbpf lingo);
  - fentry/fexit/fmod_ret programs;
  - BPF LSM programs.

This change converges all bpf_link-based attachments under LINK_CREATE
command allowing to further extend the API with features like BPF cookie
under "multiplexed" link_create section of bpf_attr.

Non-BTF-aware raw tracepoints are left under BPF_RAW_TRACEPOINT_OPEN,
but there is nothing preventing opening them up to LINK_CREATE as well.

Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Reviewed-by: default avatarKuifeng Lee <kuifeng@fb.com>
Link: https://lore.kernel.org/bpf/20220421033945.3602803-2-andrii@kernel.org
parent e8c5e1a0

kernel/bpf/syscall.c

+56 −54
Original line number Diff line number Diff line
@@ -3030,66 +3030,45 @@ static int bpf_perf_link_attach(const union bpf_attr *attr, struct bpf_prog *pro 
}

#endif /* CONFIG_PERF_EVENTS */



#define BPF_RAW_TRACEPOINT_OPEN_LAST_FIELD raw_tracepoint.prog_fd



static int bpf_raw_tracepoint_open(const union bpf_attr *attr)

static int bpf_raw_tp_link_attach(struct bpf_prog *prog,

				  const char __user *user_tp_name)

{

	struct bpf_link_primer link_primer;

	struct bpf_raw_tp_link *link;

	struct bpf_raw_event_map *btp;

	struct bpf_prog *prog;

	const char *tp_name;

	char buf[128];

	int err;



	if (CHECK_ATTR(BPF_RAW_TRACEPOINT_OPEN))

		return -EINVAL;



	prog = bpf_prog_get(attr->raw_tracepoint.prog_fd);

	if (IS_ERR(prog))

		return PTR_ERR(prog);



	switch (prog->type) {

	case BPF_PROG_TYPE_TRACING:

	case BPF_PROG_TYPE_EXT:

	case BPF_PROG_TYPE_LSM:

		if (attr->raw_tracepoint.name) {

		if (user_tp_name)

			/* The attach point for this category of programs

			 * should be specified via btf_id during program load.

			 */

			err = -EINVAL;

			goto out_put_prog;

		}

			return -EINVAL;

		if (prog->type == BPF_PROG_TYPE_TRACING &&

		    prog->expected_attach_type == BPF_TRACE_RAW_TP) {

			tp_name = prog->aux->attach_func_name;

			break;

		}

		err = bpf_tracing_prog_attach(prog, 0, 0);

		if (err >= 0)

			return err;

		goto out_put_prog;

		return bpf_tracing_prog_attach(prog, 0, 0);

	case BPF_PROG_TYPE_RAW_TRACEPOINT:

	case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:

		if (strncpy_from_user(buf,

				      u64_to_user_ptr(attr->raw_tracepoint.name),

				      sizeof(buf) - 1) < 0) {

			err = -EFAULT;

			goto out_put_prog;

		}

		if (strncpy_from_user(buf, user_tp_name, sizeof(buf) - 1) < 0)

			return -EFAULT;

		buf[sizeof(buf) - 1] = 0;

		tp_name = buf;

		break;

	default:

		err = -EINVAL;

		goto out_put_prog;

		return -EINVAL;

	}



	btp = bpf_get_raw_tracepoint(tp_name);

	if (!btp) {

		err = -ENOENT;

		goto out_put_prog;

	}

	if (!btp)

		return -ENOENT;



	link = kzalloc(sizeof(*link), GFP_USER);

	if (!link) {
@@ -3116,11 +3095,29 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr) 


out_put_btp:

	bpf_put_raw_tracepoint(btp);

out_put_prog:

	bpf_prog_put(prog);

	return err;

}



#define BPF_RAW_TRACEPOINT_OPEN_LAST_FIELD raw_tracepoint.prog_fd



static int bpf_raw_tracepoint_open(const union bpf_attr *attr)

{

	struct bpf_prog *prog;

	int fd;



	if (CHECK_ATTR(BPF_RAW_TRACEPOINT_OPEN))

		return -EINVAL;



	prog = bpf_prog_get(attr->raw_tracepoint.prog_fd);

	if (IS_ERR(prog))

		return PTR_ERR(prog);



	fd = bpf_raw_tp_link_attach(prog, u64_to_user_ptr(attr->raw_tracepoint.name));

	if (fd < 0)

		bpf_prog_put(prog);

	return fd;

}



static int bpf_prog_attach_check_attach_type(const struct bpf_prog *prog,

					     enum bpf_attach_type attach_type)

{
@@ -3189,7 +3186,13 @@ attach_type_to_prog_type(enum bpf_attach_type attach_type) 
	case BPF_CGROUP_SETSOCKOPT:

		return BPF_PROG_TYPE_CGROUP_SOCKOPT;

	case BPF_TRACE_ITER:

	case BPF_TRACE_RAW_TP:

	case BPF_TRACE_FENTRY:

	case BPF_TRACE_FEXIT:

	case BPF_MODIFY_RETURN:

		return BPF_PROG_TYPE_TRACING;

	case BPF_LSM_MAC:

		return BPF_PROG_TYPE_LSM;

	case BPF_SK_LOOKUP:

		return BPF_PROG_TYPE_SK_LOOKUP;

	case BPF_XDP:
@@ -4246,21 +4249,6 @@ static int bpf_map_do_batch(const union bpf_attr *attr, 
	return err;

}



static int tracing_bpf_link_attach(const union bpf_attr *attr, bpfptr_t uattr,

				   struct bpf_prog *prog)

{

	if (attr->link_create.attach_type != prog->expected_attach_type)

		return -EINVAL;



	if (prog->expected_attach_type == BPF_TRACE_ITER)

		return bpf_iter_link_attach(attr, uattr, prog);

	else if (prog->type == BPF_PROG_TYPE_EXT)

		return bpf_tracing_prog_attach(prog,

					       attr->link_create.target_fd,

					       attr->link_create.target_btf_id);

	return -EINVAL;

}



#define BPF_LINK_CREATE_LAST_FIELD link_create.kprobe_multi.cookies

static int link_create(union bpf_attr *attr, bpfptr_t uattr)

{
@@ -4282,15 +4270,13 @@ static int link_create(union bpf_attr *attr, bpfptr_t uattr) 


	switch (prog->type) {

	case BPF_PROG_TYPE_EXT:

		ret = tracing_bpf_link_attach(attr, uattr, prog);

		goto out;

		break;

	case BPF_PROG_TYPE_PERF_EVENT:

	case BPF_PROG_TYPE_TRACEPOINT:

		if (attr->link_create.attach_type != BPF_PERF_EVENT) {

			ret = -EINVAL;

			goto out;

		}

		ptype = prog->type;

		break;

	case BPF_PROG_TYPE_KPROBE:

		if (attr->link_create.attach_type != BPF_PERF_EVENT &&
@@ -4298,7 +4284,6 @@ static int link_create(union bpf_attr *attr, bpfptr_t uattr) 
			ret = -EINVAL;

			goto out;

		}

		ptype = prog->type;

		break;

	default:

		ptype = attach_type_to_prog_type(attr->link_create.attach_type);
@@ -4309,7 +4294,7 @@ static int link_create(union bpf_attr *attr, bpfptr_t uattr) 
		break;

	}



	switch (ptype) {

	switch (prog->type) {

	case BPF_PROG_TYPE_CGROUP_SKB:

	case BPF_PROG_TYPE_CGROUP_SOCK:

	case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
@@ -4319,8 +4304,25 @@ static int link_create(union bpf_attr *attr, bpfptr_t uattr) 
	case BPF_PROG_TYPE_CGROUP_SOCKOPT:

		ret = cgroup_bpf_link_attach(attr, prog);

		break;

	case BPF_PROG_TYPE_EXT:

		ret = bpf_tracing_prog_attach(prog,

					      attr->link_create.target_fd,

					      attr->link_create.target_btf_id);

		break;

	case BPF_PROG_TYPE_LSM:

	case BPF_PROG_TYPE_TRACING:

		ret = tracing_bpf_link_attach(attr, uattr, prog);

		if (attr->link_create.attach_type != prog->expected_attach_type) {

			ret = -EINVAL;

			goto out;

		}

		if (prog->expected_attach_type == BPF_TRACE_RAW_TP)

			ret = bpf_raw_tp_link_attach(prog, NULL);

		else if (prog->expected_attach_type == BPF_TRACE_ITER)

			ret = bpf_iter_link_attach(attr, uattr, prog);

		else

			ret = bpf_tracing_prog_attach(prog,

						      attr->link_create.target_fd,

						      attr->link_create.target_btf_id);

		break;

	case BPF_PROG_TYPE_FLOW_DISSECTOR:

	case BPF_PROG_TYPE_SK_LOOKUP: