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Message-Id: <20220518225531.558008-6-sdf@google.com>
Date: Wed, 18 May 2022 15:55:25 -0700
From: Stanislav Fomichev <sdf@...gle.com>
To: netdev@...r.kernel.org, bpf@...r.kernel.org
Cc: ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
Stanislav Fomichev <sdf@...gle.com>
Subject: [PATCH bpf-next v7 05/11] 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
Signed-off-by: Stanislav Fomichev <sdf@...gle.com>
---
include/uapi/linux/bpf.h | 5 ++
kernel/bpf/cgroup.c | 103 +++++++++++++++++++++++++++------------
kernel/bpf/syscall.c | 4 +-
3 files changed, 81 insertions(+), 31 deletions(-)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index b9d2d6de63a7..432fc5f49567 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -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 */
@@ -5911,6 +5912,10 @@ struct bpf_prog_info {
__u64 run_cnt;
__u64 recursion_misses;
__u32 verified_insns;
+ /* BTF ID of the function to attach to within BTF object identified
+ * by btf_id.
+ */
+ __u32 attach_btf_func_id;
} __attribute__((aligned(8)));
struct bpf_map_info {
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index a959cdd22870..08a1015ee09e 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -1074,6 +1074,7 @@ 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 atype;
@@ -1081,50 +1082,92 @@ static int __cgroup_bpf_query(struct cgroup *cgrp, const union bpf_attr *attr,
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;
+ enum cgroup_bpf_attach_type from_atype, to_atype;
- progs = &cgrp->bpf.progs[atype];
- flags = cgrp->bpf.flags[atype];
+ if (type == BPF_LSM_CGROUP) {
+ from_atype = CGROUP_LSM_START;
+ to_atype = CGROUP_LSM_END;
+ } else {
+ from_atype = to_cgroup_bpf_attach_type(type);
+ if (from_atype < 0)
+ return -EINVAL;
+ to_atype = from_atype;
+ }
- effective = rcu_dereference_protected(cgrp->bpf.effective[atype],
- lockdep_is_held(&cgroup_mutex));
+ for (atype = from_atype; atype <= to_atype; atype++) {
+ progs = &cgrp->bpf.progs[atype];
+ flags = cgrp->bpf.flags[atype];
- if (attr->query.query_flags & BPF_F_QUERY_EFFECTIVE)
- cnt = bpf_prog_array_length(effective);
- else
- cnt = prog_list_length(progs);
+ effective = rcu_dereference_protected(cgrp->bpf.effective[atype],
+ lockdep_is_held(&cgroup_mutex));
- 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 (attr->query.query_flags & BPF_F_QUERY_EFFECTIVE)
+ total_cnt += bpf_prog_array_length(effective);
+ else
+ total_cnt += prog_list_length(progs);
+ }
+
+ if (type != BPF_LSM_CGROUP)
+ if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))
+ return -EFAULT;
+ 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; atype++) {
+ if (total_cnt <= 0)
+ break;
- 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];
+ flags = cgrp->bpf.flags[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);
+
+ if (cnt >= total_cnt)
+ cnt = total_cnt;
+
+ if (attr->query.query_flags & BPF_F_QUERY_EFFECTIVE) {
+ ret = bpf_prog_array_copy_to_user(effective, prog_ids, cnt);
+ } else {
+ struct bpf_prog_list *pl;
+ 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;
+ }
}
+
+ if (prog_attach_flags)
+ for (i = 0; i < cnt; i++)
+ if (copy_to_user(prog_attach_flags + i, &flags, sizeof(flags)))
+ return -EFAULT;
+
+ prog_ids += cnt;
+ total_cnt -= cnt;
+ if (prog_attach_flags)
+ prog_attach_flags += cnt;
}
return ret;
}
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 5ed2093e51cc..4137583c04a2 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -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 +4067,7 @@ 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_func_id = prog->aux->attach_btf_id;
ulen = info.nr_func_info;
info.nr_func_info = prog->aux->func_info_cnt;
--
2.36.1.124.g0e6072fb45-goog
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