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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: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20220628174314.1216643-6-sdf@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Stanislav Fomichev 2022-06-28 10:43:08 -07:00 committed by Alexei Starovoitov
parent c0e19f2c9a
commit b79c9fc955
3 changed files with 74 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/uapi/linux/bpf.h
View File

@ -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 {

95
kernel/bpf/cgroup.c
View File

@ -1017,57 +1017,90 @@ 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)
return -EINVAL;
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];
}
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);
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));
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;
}
if (attr->query.query_flags & BPF_F_QUERY_EFFECTIVE) {
return bpf_prog_array_copy_to_user(effective, prog_ids, cnt);
} else {
struct bpf_prog_list *pl;
u32 id;
for (atype = from_atype; atype <= to_atype && total_cnt; atype++) {
if (attr->query.query_flags & BPF_F_QUERY_EFFECTIVE) {
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;
i = 0;
hlist_for_each_entry(pl, progs, node) {
prog = prog_list_prog(pl);
id = prog->aux->id;
if (copy_to_user(prog_ids + i, &id, sizeof(id)))
return -EFAULT;
if (++i == cnt)
break;
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);
id = prog->aux->id;
if (copy_to_user(prog_ids + i, &id, sizeof(id)))
return -EFAULT;
if (++i == cnt)
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;
}

8
kernel/bpf/syscall.c
View File

@ -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;