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Tue, 23 Jun 2020 02:22:06 +0000 Subject: Re: [PATCH bpf-next v3 09/15] bpf: add bpf_skc_to_udp6_sock() helper To: Eric Dumazet , , CC: Alexei Starovoitov , Daniel Borkmann , , Martin KaFai Lau References: <20200623003626.3072825-1-yhs@fb.com> <20200623003636.3074473-1-yhs@fb.com> From: Yonghong Song Message-ID: Date: Mon, 22 Jun 2020 19:22:03 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: BYAPR07CA0081.namprd07.prod.outlook.com (2603:10b6:a03:12b::22) To BYAPR15MB4088.namprd15.prod.outlook.com (2603:10b6:a02:c3::18) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [IPv6:2620:10d:c085:21c1::1595] (2620:10d:c090:400::5:3cd7) by BYAPR07CA0081.namprd07.prod.outlook.com (2603:10b6:a03:12b::22) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3109.21 via Frontend Transport; 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X-MS-Exchange-AntiSpam-MessageData: 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 X-MS-Exchange-CrossTenant-Network-Message-Id: 1cfc0ba0-3345-4666-c751-08d8171c392b X-MS-Exchange-CrossTenant-OriginalArrivalTime: 23 Jun 2020 02:22:06.4995 (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-CrossTenant-UserPrincipalName: Amkcc8ndHX3QJYazHhZXMazefBR6Bommdq/2EN8UcWfLxv6AzXOcrRP3NOLv4h40 X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR15MB3191 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216,18.0.687 definitions=2020-06-22_16:2020-06-22,2020-06-22 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 bulkscore=0 impostorscore=0 malwarescore=0 phishscore=0 mlxlogscore=999 spamscore=0 clxscore=1011 mlxscore=0 lowpriorityscore=0 priorityscore=1501 cotscore=-2147483648 adultscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006230016 X-FB-Internal: deliver Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 6/22/20 6:47 PM, Eric Dumazet wrote: > > > On 6/22/20 5:36 PM, Yonghong Song wrote: >> The helper is used in tracing programs to cast a socket >> pointer to a udp6_sock pointer. >> The return value could be NULL if the casting is illegal. >> >> Acked-by: Martin KaFai Lau >> Signed-off-by: Yonghong Song >> --- >> include/linux/bpf.h | 1 + >> include/uapi/linux/bpf.h | 9 ++++++++- >> kernel/trace/bpf_trace.c | 2 ++ >> net/core/filter.c | 22 ++++++++++++++++++++++ >> scripts/bpf_helpers_doc.py | 2 ++ >> tools/include/uapi/linux/bpf.h | 9 ++++++++- >> 6 files changed, 43 insertions(+), 2 deletions(-) >> >> diff --git a/include/linux/bpf.h b/include/linux/bpf.h >> index cc3f89827b89..3f5c6bb5e3a7 100644 >> --- a/include/linux/bpf.h >> +++ b/include/linux/bpf.h >> @@ -1649,6 +1649,7 @@ extern const struct bpf_func_proto bpf_skc_to_tcp6_sock_proto; >> extern const struct bpf_func_proto bpf_skc_to_tcp_sock_proto; >> extern const struct bpf_func_proto bpf_skc_to_tcp_timewait_sock_proto; >> extern const struct bpf_func_proto bpf_skc_to_tcp_request_sock_proto; >> +extern const struct bpf_func_proto bpf_skc_to_udp6_sock_proto; >> >> const struct bpf_func_proto *bpf_tracing_func_proto( >> enum bpf_func_id func_id, const struct bpf_prog *prog); >> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h >> index e256417d94c2..3f4b12c5c563 100644 >> --- a/include/uapi/linux/bpf.h >> +++ b/include/uapi/linux/bpf.h >> @@ -3276,6 +3276,12 @@ union bpf_attr { >> * Dynamically cast a *sk* pointer to a *tcp_request_sock* pointer. >> * Return >> * *sk* if casting is valid, or NULL otherwise. >> + * >> + * struct udp6_sock *bpf_skc_to_udp6_sock(void *sk) >> + * Description >> + * Dynamically cast a *sk* pointer to a *udp6_sock* pointer. >> + * Return >> + * *sk* if casting is valid, or NULL otherwise. >> */ >> #define __BPF_FUNC_MAPPER(FN) \ >> FN(unspec), \ >> @@ -3417,7 +3423,8 @@ union bpf_attr { >> FN(skc_to_tcp6_sock), \ >> FN(skc_to_tcp_sock), \ >> FN(skc_to_tcp_timewait_sock), \ >> - FN(skc_to_tcp_request_sock), >> + FN(skc_to_tcp_request_sock), \ >> + FN(skc_to_udp6_sock), >> >> /* integer value in 'imm' field of BPF_CALL instruction selects which helper >> * function eBPF program intends to call >> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c >> index de5fbe66e1ca..d10ab16c4a2f 100644 >> --- a/kernel/trace/bpf_trace.c >> +++ b/kernel/trace/bpf_trace.c >> @@ -1523,6 +1523,8 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) >> return &bpf_skc_to_tcp_timewait_sock_proto; >> case BPF_FUNC_skc_to_tcp_request_sock: >> return &bpf_skc_to_tcp_request_sock_proto; >> + case BPF_FUNC_skc_to_udp6_sock: >> + return &bpf_skc_to_udp6_sock_proto; >> #endif >> case BPF_FUNC_seq_printf: >> return prog->expected_attach_type == BPF_TRACE_ITER ? >> diff --git a/net/core/filter.c b/net/core/filter.c >> index 140fc0fdf3e1..9a98f3616273 100644 >> --- a/net/core/filter.c >> +++ b/net/core/filter.c >> @@ -9325,3 +9325,25 @@ const struct bpf_func_proto bpf_skc_to_tcp_request_sock_proto = { >> .check_btf_id = check_arg_btf_id, >> .ret_btf_id = &btf_sock_ids[BTF_SOCK_TYPE_TCP_REQ], >> }; >> + >> +BPF_CALL_1(bpf_skc_to_udp6_sock, struct sock *, sk) >> +{ >> + /* udp6_sock type is not generated in dwarf and hence btf, >> + * trigger an explicit type generation here. >> + */ >> + BTF_TYPE_EMIT(struct udp6_sock); >> + if (sk_fullsock(sk) && sk->sk_protocol == IPPROTO_UDP && > > Why is the sk_fullsock(sk) needed ? The parameter 'sk' could be a sock_common. That is why the helper name bpf_skc_to_udp6_sock implies. The sock_common cannot access sk_protocol, hence we requires sk_fullsock(sk) here. Did I miss anything? > >> + sk->sk_family == AF_INET6) >> + return (unsigned long)sk; >> + >> + return (unsigned long)NULL; >> +} >> + >> +const struct bpf_func_proto bpf_skc_to_udp6_sock_proto = { >> + .func = bpf_skc_to_udp6_sock, >> + .gpl_only = false, >> + .ret_type = RET_PTR_TO_BTF_ID_OR_NULL, >> + .arg1_type = ARG_PTR_TO_BTF_ID, >> + .check_btf_id = check_arg_btf_id, >> + .ret_btf_id = &btf_sock_ids[BTF_SOCK_TYPE_UDP6], >> +}; [...]