Re: [PATCH bpf-next v4 1/2] bpf: support BPF_PROG_QUERY for progs attached to sockmap

[Yonghong Song]

On 11/2/21 7:23 PM, zhudi (E) wrote:
> > On 11/2/21 1:48 AM, Di Zhu wrote:
> > > 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@xxxxxxxxxx>
> > > ---
> > >    include/linux/bpf.h  |  9 +++++
> > >    kernel/bpf/syscall.c |  5 +++
> > >    net/core/sock_map.c  | 88
> > ++++++++++++++++++++++++++++++++++++++++----
> > >    3 files changed, 95 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> > > index d604c8251d88..594ca91992db 100644
> > > --- a/include/linux/bpf.h
> > > +++ b/include/linux/bpf.h
> > > @@ -1961,6 +1961,9 @@ 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);
> >
> > All previous functions are with prefix "sock_map". Why you choose
> > a different prefix "sockmap"?
>
> Thanks for all your suggestions, I will make changes to the inappropriate code.
>
> > > +
> > >    void sock_map_unhash(struct sock *sk);
> > >    void sock_map_close(struct sock *sk, long timeout);
> > >    #else
> > > @@ -2014,6 +2017,12 @@ 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..17faeff8f85f 100644
> > > --- a/kernel/bpf/syscall.c
> > > +++ b/kernel/bpf/syscall.c
> > > @@ -3275,6 +3275,11 @@ 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:
> > > +	case BPF_SK_SKB_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..ca65ed0004d3 100644
> > > --- a/net/core/sock_map.c
> > > +++ b/net/core/sock_map.c
> > > @@ -1412,38 +1412,50 @@ static struct sk_psock_progs
> > *sock_map_progs(struct bpf_map *map)
> > >    	return NULL;
> > >    }
> > >
> > > -static int sock_map_prog_update(struct bpf_map *map, struct bpf_prog
> > *prog,
> > > -				struct bpf_prog *old, u32 which)
> > > +static int sock_map_prog_lookup(struct bpf_map *map, struct bpf_prog
> > **pprog[],
> >
> > Can we just change "**pprog[]" to "***pprog"? In the code, you really
> > just pass the address of the decl "struct bpf_prog **pprog;" to the
> > function.
> >
> > > +				u32 which)
> >
> > Some format issue here?
>
>
> Format is right, passed the checkpatch script check.

Sorry about this. I guess my reply formating cheated me:

>>> +static int sock_map_prog_lookup(struct bpf_map *map, struct bpf_prog
>> **pprog[],
>>> +				u32 which)

I see a larger misalignment between "struct bpf_map *map" and
"u32 which" in the reply email. But looking at original
patch, there are no issues.

> > >    {
> > >    	struct sk_psock_progs *progs = sock_map_progs(map);
> > > -	struct bpf_prog **pprog;
> > >
> > >    	if (!progs)
> > >    		return -EOPNOTSUPP;
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