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Fri, 10 Apr 2020 06:09:57 +0000 Subject: Re: [RFC PATCH bpf-next 05/16] bpf: create file or anonymous dumpers To: Alexei Starovoitov CC: Andrii Nakryiko , , Martin KaFai Lau , , Alexei Starovoitov , Daniel Borkmann , References: <20200408232520.2675265-1-yhs@fb.com> <20200408232526.2675664-1-yhs@fb.com> <20200410030017.errh35srmbmd7uk5@ast-mbp.dhcp.thefacebook.com> From: Yonghong Song Message-ID: <814a49f7-68b5-e796-7254-2a4ce9c0af74@fb.com> Date: Thu, 9 Apr 2020 23:09:39 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 In-Reply-To: <20200410030017.errh35srmbmd7uk5@ast-mbp.dhcp.thefacebook.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: CO2PR04CA0154.namprd04.prod.outlook.com (2603:10b6:104::32) To MW3PR15MB3883.namprd15.prod.outlook.com (2603:10b6:303:51::22) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from rutu-mbp.dhcp.thefacebook.com (2620:10d:c090:400::5:75b7) by CO2PR04CA0154.namprd04.prod.outlook.com (2603:10b6:104::32) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2900.20 via Frontend Transport; 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X-Microsoft-Antispam-Message-Info: KOfX1C5Vn1ixwn8KKYIqVyrqFdUuKWNrrN0z6GAJ5usiqWOkhkbeu13HGD9X669PBowmWmtiW9YD36UnjybHXFFYPK0+txZh3vV8ymuFJ64eaVVB/s7ZttxI1Gx/ziSrbHmMAzxYRW4zm9OuA6zWPbh7LEsUPJe/N7uXRStNIo7LqqOVNshVAk1t5l44yrLlc/UBXR80oazTj6DgsOCg7NClCWBut08AZBFS5odmooSL/b55lbr+qdV5NsOk7tA64aaFzJG/kjoPQUW9c+GcAa6uZWgGuivqygUCJaUYTWQiCjyPhXw9YEDj+2tV9wpsJjkmxGTKFjMA8KWI6h2qP7iakUiQ56owCfCXpBpUBhBBe4odNBOiFSKWkav5y+atL/7cHxvubg1rQUfBd3Rba5dUE4baCxypPR/+nkpmsDHqmvyQSQ4Rgnrze6IUnOXr X-MS-Exchange-AntiSpam-MessageData: aHMNWT1ZTLuREZdKKAJrxEb0eWqqpz3ADBrq6fmMhHLp6zwWx0pHCEs5IOEsP3jBr+4HFpHRIaMno3lEDcP233udw3KrSdkELHz5c8/7gM4mrx8WnFbCxe+fqb/12b5tipeKguRCN4HtiG7swSEBoXNMXVRaU/fBtS6pVozLd67xAzQQfJ+/+lKktMqXtcUK X-MS-Exchange-CrossTenant-Network-Message-Id: ee4acfaf-e175-4ce7-0625-08d7dd15caed X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Apr 2020 06:09:56.8690 (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: gjRo5rHXNJVbSV+CyxS/8H3ysRTvga0F3f1EGGACvtJS7jwVUTp0agrk/NI4c0wr X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW3PR15MB3977 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.676 definitions=2020-04-10_01:2020-04-07,2020-04-10 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 phishscore=0 mlxscore=0 priorityscore=1501 malwarescore=0 suspectscore=0 adultscore=0 lowpriorityscore=0 spamscore=0 bulkscore=0 clxscore=1015 mlxlogscore=999 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2004100052 X-FB-Internal: deliver Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 4/9/20 8:00 PM, Alexei Starovoitov wrote: > On Wed, Apr 08, 2020 at 04:25:26PM -0700, Yonghong Song wrote: >> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h >> index 0f1cbed446c1..b51d56fc77f9 100644 >> --- a/include/uapi/linux/bpf.h >> +++ b/include/uapi/linux/bpf.h >> @@ -354,6 +354,7 @@ enum { >> /* Flags for accessing BPF object from syscall side. */ >> BPF_F_RDONLY = (1U << 3), >> BPF_F_WRONLY = (1U << 4), >> + BPF_F_DUMP = (1U << 5), > ... >> static int bpf_obj_pin(const union bpf_attr *attr) >> { >> - if (CHECK_ATTR(BPF_OBJ) || attr->file_flags != 0) >> + if (CHECK_ATTR(BPF_OBJ) || attr->file_flags & ~BPF_F_DUMP) >> return -EINVAL; >> >> + if (attr->file_flags == BPF_F_DUMP) >> + return bpf_dump_create(attr->bpf_fd, >> + u64_to_user_ptr(attr->dumper_name)); >> + >> return bpf_obj_pin_user(attr->bpf_fd, u64_to_user_ptr(attr->pathname)); >> } > > I think kernel can be a bit smarter here. There is no need for user space > to pass BPF_F_DUMP flag to kernel just to differentiate the pinning. > Can prog attach type be used instead? Good point. Yes, no need for BPF_F_DUMP, expected_attach_type is enough. Will change.