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bpf: support BPF_PROG_QUERY for BPF_FLOW_DISSECTOR attach_type

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target_fd is target namespace. If there is a flow dissector BPF program
attached to that namespace, its (single) id is returned.

v5:
* drop net ref right after rcu unlock (Daniel Borkmann)

v4:
* add missing put_net (Jann Horn)

v3:
* add missing inline to skb_flow_dissector_prog_query static def
  (kbuild test robot <lkp@intel.com>)

v2:
* don't sleep in rcu critical section (Jakub Kicinski)
* check input prog_cnt (exit early)

Cc: Jann Horn <jannh@google.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Stanislav Fomichev 2019-04-25 14:37:23 -07:00 committed by Daniel Borkmann
parent ead442a0f9
commit 118c8e9ae6
3 changed files with 49 additions and 0 deletions
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8
include/linux/skbuff.h
View File

@ -1258,11 +1258,19 @@ void skb_flow_dissector_init(struct flow_dissector *flow_dissector,
unsigned int key_count);
#ifdef CONFIG_NET
int skb_flow_dissector_prog_query(const union bpf_attr *attr,
union bpf_attr __user *uattr);
int skb_flow_dissector_bpf_prog_attach(const union bpf_attr *attr,
struct bpf_prog *prog);
int skb_flow_dissector_bpf_prog_detach(const union bpf_attr *attr);
#else
static inline int skb_flow_dissector_prog_query(const union bpf_attr *attr,
union bpf_attr __user *uattr)
{
return -EOPNOTSUPP;
}
static inline int skb_flow_dissector_bpf_prog_attach(const union bpf_attr *attr,
struct bpf_prog *prog)
{

2
kernel/bpf/syscall.c
View File

@ -2009,6 +2009,8 @@ static int bpf_prog_query(const union bpf_attr *attr,
break;
case BPF_LIRC_MODE2:
return lirc_prog_query(attr, uattr);
case BPF_FLOW_DISSECTOR:
return skb_flow_dissector_prog_query(attr, uattr);
default:
return -EINVAL;
}

39
net/core/flow_dissector.c
View File

@ -65,6 +65,45 @@ void skb_flow_dissector_init(struct flow_dissector *flow_dissector,
}
EXPORT_SYMBOL(skb_flow_dissector_init);
int skb_flow_dissector_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_id, prog_cnt = 0, flags = 0;
struct bpf_prog *attached;
struct net *net;
if (attr->query.query_flags)
return -EINVAL;
net = get_net_ns_by_fd(attr->query.target_fd);
if (IS_ERR(net))
return PTR_ERR(net);
rcu_read_lock();
attached = rcu_dereference(net->flow_dissector_prog);
if (attached) {
prog_cnt = 1;
prog_id = attached->aux->id;
}
rcu_read_unlock();
put_net(net);
if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))
return -EFAULT;
if (copy_to_user(&uattr->query.prog_cnt, &prog_cnt, sizeof(prog_cnt)))
return -EFAULT;
if (!attr->query.prog_cnt || !prog_ids || !prog_cnt)
return 0;
if (copy_to_user(prog_ids, &prog_id, sizeof(u32)))
return -EFAULT;
return 0;
}
int skb_flow_dissector_bpf_prog_attach(const union bpf_attr *attr,
struct bpf_prog *prog)
{