Commit b79c9fc9 authored by Stanislav Fomichev's avatar Stanislav Fomichev Committed by Alexei Starovoitov
Browse files

bpf: implement BPF_PROG_QUERY for BPF_LSM_CGROUP 



We have two options:
1. Treat all BPF_LSM_CGROUP the same, regardless of attach_btf_id
2. Treat BPF_LSM_CGROUP+attach_btf_id as a separate hook point

I was doing (2) in the original patch, but switching to (1) here:

* bpf_prog_query returns all attached BPF_LSM_CGROUP programs
regardless of attach_btf_id
* attach_btf_id is exported via bpf_prog_info

Reviewed-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarStanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20220628174314.1216643-6-sdf@google.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent c0e19f2c

include/uapi/linux/bpf.h

+3 −0
Original line number Diff line number Diff line
@@ -1432,6 +1432,7 @@ union bpf_attr { 
		__u32		attach_flags;

		__aligned_u64	prog_ids;

		__u32		prog_cnt;

		__aligned_u64	prog_attach_flags; /* output: per-program attach_flags */

	} query;



	struct { /* anonymous struct used by BPF_RAW_TRACEPOINT_OPEN command */
@@ -6076,6 +6077,8 @@ struct bpf_prog_info { 
	__u64 run_cnt;

	__u64 recursion_misses;

	__u32 verified_insns;

	__u32 attach_btf_obj_id;

	__u32 attach_btf_id;

} __attribute__((aligned(8)));



struct bpf_map_info {

kernel/bpf/cgroup.c

+64 −31
Original line number Diff line number Diff line
@@ -1017,48 +1017,68 @@ static int cgroup_bpf_detach(struct cgroup *cgrp, struct bpf_prog *prog, 
static int __cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,

			      union bpf_attr __user *uattr)

{

	__u32 __user *prog_attach_flags = u64_to_user_ptr(attr->query.prog_attach_flags);

	__u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);

	enum bpf_attach_type type = attr->query.attach_type;

	enum cgroup_bpf_attach_type from_atype, to_atype;

	enum cgroup_bpf_attach_type atype;

	struct bpf_prog_array *effective;

	struct hlist_head *progs;

	struct bpf_prog *prog;

	int cnt, ret = 0, i;

	int total_cnt = 0;

	u32 flags;



	atype = to_cgroup_bpf_attach_type(type);

	if (atype < 0)

	if (type == BPF_LSM_CGROUP) {

		if (attr->query.prog_cnt && prog_ids && !prog_attach_flags)

			return -EINVAL;



	progs = &cgrp->bpf.progs[atype];

	flags = cgrp->bpf.flags[atype];

		from_atype = CGROUP_LSM_START;

		to_atype = CGROUP_LSM_END;

		flags = 0;

	} else {

		from_atype = to_cgroup_bpf_attach_type(type);

		if (from_atype < 0)

			return -EINVAL;

		to_atype = from_atype;

		flags = cgrp->bpf.flags[from_atype];

	}



	for (atype = from_atype; atype <= to_atype; atype++) {

		if (attr->query.query_flags & BPF_F_QUERY_EFFECTIVE) {

			effective = rcu_dereference_protected(cgrp->bpf.effective[atype],

							      lockdep_is_held(&cgroup_mutex));



	if (attr->query.query_flags & BPF_F_QUERY_EFFECTIVE)

		cnt = bpf_prog_array_length(effective);

	else

		cnt = prog_list_length(progs);

			total_cnt += bpf_prog_array_length(effective);

		} else {

			total_cnt += prog_list_length(&cgrp->bpf.progs[atype]);

		}

	}



	if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))

		return -EFAULT;

	if (copy_to_user(&uattr->query.prog_cnt, &cnt, sizeof(cnt)))

	if (copy_to_user(&uattr->query.prog_cnt, &total_cnt, sizeof(total_cnt)))

		return -EFAULT;

	if (attr->query.prog_cnt == 0 || !prog_ids || !cnt)

	if (attr->query.prog_cnt == 0 || !prog_ids || !total_cnt)

		/* return early if user requested only program count + flags */

		return 0;

	if (attr->query.prog_cnt < cnt) {

		cnt = attr->query.prog_cnt;



	if (attr->query.prog_cnt < total_cnt) {

		total_cnt = attr->query.prog_cnt;

		ret = -ENOSPC;

	}



	for (atype = from_atype; atype <= to_atype && total_cnt; atype++) {

		if (attr->query.query_flags & BPF_F_QUERY_EFFECTIVE) {

		return bpf_prog_array_copy_to_user(effective, prog_ids, cnt);

			effective = rcu_dereference_protected(cgrp->bpf.effective[atype],

							      lockdep_is_held(&cgroup_mutex));

			cnt = min_t(int, bpf_prog_array_length(effective), total_cnt);

			ret = bpf_prog_array_copy_to_user(effective, prog_ids, cnt);

		} else {

			struct hlist_head *progs;

			struct bpf_prog_list *pl;

			struct bpf_prog *prog;

			u32 id;



			progs = &cgrp->bpf.progs[atype];

			cnt = min_t(int, prog_list_length(progs), total_cnt);

			i = 0;

			hlist_for_each_entry(pl, progs, node) {

				prog = prog_list_prog(pl);
@@ -1069,6 +1089,19 @@ static int __cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr, 
					break;

			}

		}



		if (prog_attach_flags) {

			flags = cgrp->bpf.flags[atype];



			for (i = 0; i < cnt; i++)

				if (copy_to_user(prog_attach_flags + i, &flags, sizeof(flags)))

					return -EFAULT;

			prog_attach_flags += cnt;

		}



		prog_ids += cnt;

		total_cnt -= cnt;

	}

	return ret;

}

kernel/bpf/syscall.c

+7 −1
Original line number Diff line number Diff line
@@ -3520,7 +3520,7 @@ static int bpf_prog_detach(const union bpf_attr *attr) 
	}

}



#define BPF_PROG_QUERY_LAST_FIELD query.prog_cnt

#define BPF_PROG_QUERY_LAST_FIELD query.prog_attach_flags



static int bpf_prog_query(const union bpf_attr *attr,

			  union bpf_attr __user *uattr)
@@ -3556,6 +3556,7 @@ static int bpf_prog_query(const union bpf_attr *attr, 
	case BPF_CGROUP_SYSCTL:

	case BPF_CGROUP_GETSOCKOPT:

	case BPF_CGROUP_SETSOCKOPT:

	case BPF_LSM_CGROUP:

		return cgroup_bpf_prog_query(attr, uattr);

	case BPF_LIRC_MODE2:

		return lirc_prog_query(attr, uattr);
@@ -4066,6 +4067,11 @@ static int bpf_prog_get_info_by_fd(struct file *file, 


	if (prog->aux->btf)

		info.btf_id = btf_obj_id(prog->aux->btf);

	info.attach_btf_id = prog->aux->attach_btf_id;

	if (prog->aux->attach_btf)

		info.attach_btf_obj_id = btf_obj_id(prog->aux->attach_btf);

	else if (prog->aux->dst_prog)

		info.attach_btf_obj_id = btf_obj_id(prog->aux->dst_prog->aux->attach_btf);



	ulen = info.nr_func_info;

	info.nr_func_info = prog->aux->func_info_cnt;