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Date: Tue, 19 Oct 2021 20:58:56 +0800
From: Di Zhu <zhudi2@...wei.com>
To: <davem@...emloft.net>, <ast@...nel.org>, <daniel@...earbox.net>,
<andrii@...nel.org>, <kafai@...com>
CC: <bpf@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<zhudi2@...wei.com>
Subject: [PATCH] bpf: support BPF_PROG_QUERY for progs attached to sockmap
Right now there is no way to query whether BPF programs are
attached to a sockmap or not.
we can use the standard interface in libbpf to query, such as:
bpf_prog_query(mapFd, BPF_SK_SKB_STREAM_PARSER, 0, NULL, ...);
the mapFd is the fd of sockmap.
Signed-off-by: Di Zhu <zhudi2@...wei.com>
---
include/linux/bpf.h | 8 +++++
kernel/bpf/syscall.c | 4 +++
net/core/sock_map.c | 81 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 93 insertions(+)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 1c7fd7c4c6d3..69cf70b077d5 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1959,6 +1959,8 @@ int bpf_prog_test_run_syscall(struct bpf_prog *prog,
int sock_map_get_from_fd(const union bpf_attr *attr, struct bpf_prog *prog);
int sock_map_prog_detach(const union bpf_attr *attr, enum bpf_prog_type ptype);
int sock_map_update_elem_sys(struct bpf_map *map, void *key, void *value, u64 flags);
+int sockmap_bpf_prog_query(const union bpf_attr *attr,
+ union bpf_attr __user *uattr);
void sock_map_unhash(struct sock *sk);
void sock_map_close(struct sock *sk, long timeout);
#else
@@ -2012,6 +2014,12 @@ static inline int sock_map_update_elem_sys(struct bpf_map *map, void *key, void
{
return -EOPNOTSUPP;
}
+
+static inline int sockmap_bpf_prog_query(const union bpf_attr *attr,
+ union bpf_attr __user *uattr)
+{
+ return -EINVAL;
+}
#endif /* CONFIG_BPF_SYSCALL */
#endif /* CONFIG_NET && CONFIG_BPF_SYSCALL */
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 4e50c0bfdb7d..3049b9506583 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3275,6 +3275,10 @@ static int bpf_prog_query(const union bpf_attr *attr,
case BPF_FLOW_DISSECTOR:
case BPF_SK_LOOKUP:
return netns_bpf_prog_query(attr, uattr);
+ case BPF_SK_SKB_STREAM_PARSER:
+ case BPF_SK_SKB_STREAM_VERDICT:
+ case BPF_SK_MSG_VERDICT:
+ return sockmap_bpf_prog_query(attr, uattr);
default:
return -EINVAL;
}
diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index e252b8ec2b85..32688a1b78c6 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -1451,6 +1451,87 @@ static int sock_map_prog_update(struct bpf_map *map, struct bpf_prog *prog,
return 0;
}
+static int sock_map_prog_lookup(struct bpf_map *map, struct bpf_prog **prog,
+ u32 which)
+{
+ struct sk_psock_progs *progs = sock_map_progs(map);
+
+ if (!progs)
+ return -EOPNOTSUPP;
+
+ switch (which) {
+ case BPF_SK_MSG_VERDICT:
+ *prog = READ_ONCE(progs->msg_parser);
+ break;
+#if IS_ENABLED(CONFIG_BPF_STREAM_PARSER)
+ case BPF_SK_SKB_STREAM_PARSER:
+ *prog = READ_ONCE(progs->skb_parser);
+ break;
+#endif
+ case BPF_SK_SKB_STREAM_VERDICT:
+ *prog = READ_ONCE(progs->skb_verdict);
+ break;
+ default:
+ return -EOPNOTSUPP;
+ }
+
+ return 0;
+}
+
+int sockmap_bpf_prog_query(const union bpf_attr *attr,
+ union bpf_attr __user *uattr)
+{
+ __u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
+ u32 prog_cnt = 0, flags = 0;
+ u32 ufd = attr->target_fd;
+ struct bpf_map *map;
+ struct bpf_prog *prog;
+ struct fd f;
+ int ret;
+
+ if (attr->query.query_flags)
+ return -EINVAL;
+
+ if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))
+ return -EFAULT;
+
+ f = fdget(ufd);
+ map = __bpf_map_get(f);
+ if (IS_ERR(map))
+ return PTR_ERR(map);
+
+ rcu_read_lock();
+
+ ret = sock_map_prog_lookup(map, &prog, attr->query.attach_type);
+ if (ret)
+ goto end;
+
+ prog_cnt = (!prog) ? 0 : 1;
+ if (copy_to_user(&uattr->query.prog_cnt, &prog_cnt, sizeof(prog_cnt))) {
+ ret = -EFAULT;
+ goto end;
+ }
+
+ if (!attr->query.prog_cnt || !prog_ids || !prog_cnt)
+ goto end;
+
+ prog = bpf_prog_inc_not_zero(prog);
+ if (IS_ERR(prog)) {
+ ret = PTR_ERR(prog);
+ goto end;
+ }
+
+ if (copy_to_user(prog_ids, &prog->aux->id, sizeof(u32)))
+ ret = -EFAULT;
+
+ bpf_prog_put(prog);
+
+end:
+ rcu_read_unlock();
+ fdput(f);
+ return ret;
+}
+
static void sock_map_unlink(struct sock *sk, struct sk_psock_link *link)
{
switch (link->map->map_type) {
--
2.23.0
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