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charset="us-ascii" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: 75ce0b43-8338-42a8-b2cb-08d6db13419a X-MS-Exchange-CrossTenant-originalarrivaltime: 17 May 2019 22:01:47.4885 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR15MB1903 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-05-17_14:,, signatures=0 X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Fri, May 17, 2019 at 02:51:48PM -0700, Eric Dumazet wrote: >=20 >=20 > On 5/17/19 2:21 PM, Martin KaFai Lau wrote: > > The BPF_FUNC_sk_lookup_xxx helpers return RET_PTR_TO_SOCKET_OR_NULL. > > Meaning a fullsock ptr and its fullsock's fields in bpf_sock can be > > accessed, e.g. type, protocol, mark and priority. > > Some new helper, like bpf_sk_storage_get(), also expects > > ARG_PTR_TO_SOCKET is a fullsock. > >=20 > > bpf_sk_lookup() currently calls sk_to_full_sk() before returning. > > However, the ptr returned from sk_to_full_sk() is not guaranteed > > to be a fullsock. For example, it cannot get a fullsock if sk > > is in TCP_TIME_WAIT. > >=20 > > This patch checks for sk_fullsock() before returning. If it is not > > a fullsock, sock_gen_put() is called if needed and then returns NULL. > >=20 > > Fixes: 6acc9b432e67 ("bpf: Add helper to retrieve socket in BPF") > > Cc: Joe Stringer > > Signed-off-by: Martin KaFai Lau > > --- > > net/core/filter.c | 16 ++++++++++++++-- > > 1 file changed, 14 insertions(+), 2 deletions(-) > >=20 > > diff --git a/net/core/filter.c b/net/core/filter.c > > index 55bfc941d17a..85def5a20aaf 100644 > > --- a/net/core/filter.c > > +++ b/net/core/filter.c > > @@ -5337,8 +5337,14 @@ __bpf_sk_lookup(struct sk_buff *skb, struct bpf_= sock_tuple *tuple, u32 len, > > struct sock *sk =3D __bpf_skc_lookup(skb, tuple, len, caller_net, > > ifindex, proto, netns_id, flags); > > =20 > > - if (sk) > > + if (sk) { > > sk =3D sk_to_full_sk(sk); > > + if (!sk_fullsock(sk)) { > > + if (!sock_flag(sk, SOCK_RCU_FREE)) > > + sock_gen_put(sk); >=20 > This looks a bit convoluted/weird. >=20 > What about telling/asking __bpf_skc_lookup() to not return a non fullsock= instead ? It is becausee some other helpers, like BPF_FUNC_skc_lookup_tcp, can return non fullsock. >=20 > > + return NULL; > > + } > > + } > > =20 > > return sk; > > } > > @@ -5369,8 +5375,14 @@ bpf_sk_lookup(struct sk_buff *skb, struct bpf_so= ck_tuple *tuple, u32 len, > > struct sock *sk =3D bpf_skc_lookup(skb, tuple, len, proto, netns_id, > > flags); > > =20 > > - if (sk) > > + if (sk) { > > sk =3D sk_to_full_sk(sk); > > + if (!sk_fullsock(sk)) { > > + if (!sock_flag(sk, SOCK_RCU_FREE)) > > + sock_gen_put(sk); > > + return NULL; > > + } > > + } > > =20 > > return sk; > > } > >=20