From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932510AbdKGWEv (ORCPT ); Tue, 7 Nov 2017 17:04:51 -0500 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:41190 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754183AbdKGWEt (ORCPT ); Tue, 7 Nov 2017 17:04:49 -0500 Subject: Re: [RFC PATCH] bpf: Add helpers to read useful task_struct members To: Y Song References: <20171103065833.8076-1-sandipan@linux.vnet.ibm.com> <94a4761f-1b51-8b70-fb7f-3cea91c69717@fb.com> <1509815348.8zu63uatdo.naveen@linux.ibm.com> <4acdc081-341d-ee91-a591-b1d331a8c8d5@fb.com> <1509982000.092la4257a.naveen@linux.ibm.com> <1510042830.62prnydrlw.naveen@linux.ibm.com> CC: "Naveen N. Rao" , netdev , Sandipan Das , Brendan Gregg , Daniel Borkmann , Martin KaFai Lau , Kees Cook , From: Alexei Starovoitov Message-ID: <328c2dff-7d6d-0dc0-46cf-ae715845903e@fb.com> Date: Wed, 8 Nov 2017 07:04:02 +0900 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [2620:10d:c094:180::1:23e4] X-ClientProxiedBy: HK2PR02CA0172.apcprd02.prod.outlook.com (2603:1096:201:1f::32) To BL2PR15MB0961.namprd15.prod.outlook.com (2603:10b6:201:15::23) X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: a431223b-07bf-4c6c-e788-08d5262b81cd X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:(22001)(4534020)(4602075)(4627115)(201703031133081)(201702281549075)(2017052603249);SRVR:BL2PR15MB0961; X-Microsoft-Exchange-Diagnostics: 1;BL2PR15MB0961;3:twkhrOjuBpzgkSLyizEr3DshoWkwf7JeJlApwAYi84r+PiH2uGmgAnSKlRQBoYc5t8X+rkKYpIUGU47jHbxT+/mz/h0nMi3Z3pySxVAGBISeMftOZHrHNxbnQlrWIH6yUzJ2Ht14w/7BobITO7Ym7qv9/4sHF0WE7tN5v3bn7m4ZE96Z5xy23D7MgpmSqKQx3kYBlt279afFnMUwvHmo7RoSx/ji97J4/fnPcfPsOF9RiNNpfMncZXZQgaV7IosP;25:DKJmkhDw4Ox3r0aCkszm/SfsUnG7ejqLgBrntT1HFY8uxCXyAi6npNdWjwMAY1+cbgxh4Os4qjHpAlBnZhhJQV2QAb0tgLsu9OesdiqBP2zEzSgd9gkYkxbVfQ+o2aXh9rrcmoMQhPeMCs8qyWp8VlqZUnPBQwbX30y1Qc7Lg3S6cS6sRqRMFaY2lK+o4B9cq+SRPV4tAN7eOnfhUmzqqUaBA7/aiQvrRR+IBjjHiywkj8YRDJZ9MbdjxepdXyL7Et1861b6g5AD5ZflYJ949a1X1AXWYIc+G5Jh6gV5EMB48lJhEcHk4UqLT6BIZrWZ0uGop6iVKHO43Fo4y5GkOw==;31:MglleMgNubWla7kCGZynBPxdTRzU+k4ApV0LeaL3NzW16OLoTaXJCybJPRQg8cX05aa5gg826ulQYi6vS6/qQhSNwHzCdjTrXZFHXj2poFNM53XOKcqB825YBmhUve3+gTR77sccERB6FpeRKQnm7Xrw9sUaNSHHj8gPbBGhC8j4/NFEHM9C9VhFpyUQLbeGiIuHwPq3tZopxQS0bOfL0ph8mwrLXghLMjD4fmFsmq0= X-MS-TrafficTypeDiagnostic: BL2PR15MB0961: X-Microsoft-Exchange-Diagnostics: 1;BL2PR15MB0961;20: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;4:99+VpxYLFxd+SItx8hnVYjOpsfyUVTPDvgGfxLJ3tP3Zha51h2Gt9me6g+lA3vVeJPIWyZp5tEDhkSWAw1DHAFrYnOrDF/gELOGmuWBr5PqnvJCKjPg+5sSI/X5k0IuHjrYPiCvfNjUn03btEp71mk6dHyujF/RsvnU/LpUs2Exs9m1tJzmtV7oueNt4gaW6pRXYaI0NOxe2JU3UOxGPG24O4oqmPMz7X3R+KIg+38bpbrV8ofoaR+26d1yI/3UeyRa4PKtZacO+NE4mJX15qCaegxQo0ZvFvT5CdafWUdlNnbaWi+UyGh6JM4Mt2PKWiv8S+mJ9VMUSwiv8aHorAUP/fVdxsy3VQKTTL9GOreE= X-Exchange-Antispam-Report-Test: UriScan:(67672495146484)(104084551191319); X-Microsoft-Antispam-PRVS: X-Exchange-Antispam-Report-CFA-Test: BCL:0;PCL:0;RULEID:(100000700101)(100105000095)(100000701101)(100105300095)(100000702101)(100105100095)(11241501159)(6040450)(2401047)(8121501046)(5005006)(3231021)(93006095)(93001095)(100000703101)(100105400095)(10201501046)(3002001)(6041248)(20161123555025)(20161123564025)(20161123560025)(20161123562025)(20161123558100)(201703131423075)(201702281528075)(201703061421075)(201703061406153)(6072148)(201708071742011)(100000704101)(100105200095)(100000705101)(100105500095);SRVR:BL2PR15MB0961;BCL:0;PCL:0;RULEID:(100000800101)(100110000095)(100000801101)(100110300095)(100000802101)(100110100095)(100000803101)(100110400095)(100000804101)(100110200095)(100000805101)(100110500095);SRVR:BL2PR15MB0961; X-Forefront-PRVS: 0484063412 X-Forefront-Antispam-Report: SFV:NSPM;SFS:(10019020)(6009001)(376002)(346002)(199003)(189002)(24454002)(33646002)(106356001)(31686004)(1706002)(105586002)(6116002)(1411001)(478600001)(5660300001)(53546010)(2950100002)(6916009)(6666003)(6246003)(4326008)(53936002)(65826007)(8676002)(81156014)(81166006)(83506002)(68736007)(8936002)(25786009)(2906002)(229853002)(65956001)(65806001)(50466002)(6486002)(64126003)(39060400002)(47776003)(230700001)(36756003)(97736004)(305945005)(23676003)(7736002)(86362001)(189998001)(31696002)(67846002)(76176999)(54906003)(54356999)(58126008)(93886005)(316002)(50986999)(101416001)(42262002);DIR:OUT;SFP:1102;SCL:1;SRVR:BL2PR15MB0961;H:[IPv6:2620:10d:c0e1:1110::1004];FPR:;SPF:None;PTR:InfoNoRecords;A:1;MX:1;LANG:en; X-Microsoft-Exchange-Diagnostics: =?utf-8?B?MTtCTDJQUjE1TUIwOTYxOzIzOmhFaklhMUdUamk0c2trRUdMS0I2dnZ2NVk1?= =?utf-8?B?V2daTm12Z2ltQ1NwTUJIUVVnL0YrdjZobllyUmFVZGFmQ2FGSFhva1NqeWdT?= =?utf-8?B?cjkwblN3M3JLdW1zSFVOOTdHYzVLRW5JMExPYURoTnUzN0JVNjMzbVlRbDRo?= =?utf-8?B?QkszRk0wZ2ltdkkzelpPeG5QZFVhRzQzbG41c1BPc1VOOG85SGpOWi9mYjgv?= =?utf-8?B?SDNBNUN2NGRvMGFIbXRHR0VFOExDNlNQTTBSNDBZL2VXTmZPdGlHZmR0dlR2?= =?utf-8?B?YlhwVHg0bjNWQmJvdEIvRWg4WTRqSDEvYkwyekp6ck9USG5QT0pzZEJtU3JJ?= =?utf-8?B?U05jNWRjaFhTZGEwUGF0aGlYVlluVm5acURtbE00SjFobjlWa3c2RWlUcmU2?= =?utf-8?B?UFRxSlF0Tmx0VjRReDBHellkS2xQSklWZTU4MmNVUzlwNmNTZnh2UlRvTEdV?= =?utf-8?B?SjVjU1pRREFEazQ1cFFLbDBlNFZHcEQvSXR4azZVcmJ1ZVcvN0RVM29hdWlp?= =?utf-8?B?Y1UxM1pFQ0ZLbjFWZmFma21XVll3S2V2UzE2enFqTEVjMlRWTVpwSCtBS1FM?= =?utf-8?B?TlV0Wjg2SlluKzFERkNSU201RzZ1NUZ4bUtOVm5qL2hsaDJSRHJQN3pqcDNV?= =?utf-8?B?WjYybG80TXlaM2k3OTU5eW1CRTVjVk1tY1QxcnlsMzJ3Ynpzb3VaSlN2SDNr?= =?utf-8?B?NlZXbVhyNHZGaU1GRHBZYUFmMm9ubTlyNFNLMnpOVUxlMk9kYzQrMzd0VFR6?= =?utf-8?B?MGNZVWVSRHZSdkZBOXFkTEM4S2cxN3hTY1pVT3hTSFpkOVFBMFc3U1NLY2Uv?= =?utf-8?B?WTQyOUdtbnRkNitCTzZUdDVmS0d5VU9SZTFWdWhaQkNTeXQwZy9MWmVqSVU4?= =?utf-8?B?SEV0TVkvN1grWCtIUC9SM1pCVFNsbWZmbzNSWlJ6QnZuQjVkU2NSY2w3ZTVx?= =?utf-8?B?R1IvUEJRRUN3U1IwOTRNeWRWMGhtYW5BbzQ5ZXNSbXYzUER6NCtWZE5FNm5M?= =?utf-8?B?VExROVRieUNTRDAvTzkzbi9EV1hHdVBubTVKNVQ4c1FZL21RTGNKMlRiZGdF?= =?utf-8?B?UTF4bWU3cHJpa2dUL1hmdVhrZXdMTlNUS3dBWWxvZlBPMW42RDlaZWNmV0Z0?= =?utf-8?B?d0VkUE5UaWF2THlvNDJJWWozUStEQ0tyMldvbXBPcjlINXZ2U290M3hweGx4?= =?utf-8?B?UDZxNS9jb0VZcnNROEFibmFQRTNYZW9nWlAyV251Q2VnRGpuODMrTzF2a0tr?= =?utf-8?B?NVJNR2JDWERFTmtkY3ZqZTZ3RXBTTWNOVStvM0dXOGVVclFhMnJhVWtNZnV1?= =?utf-8?B?SmExV3RpdFU1VzVmc0g0Tm5oZjRONWV5MXVKcW9GbnYzNjNlVkZNZ2NncTFY?= =?utf-8?B?SmZ4YmhzWkdqYjVRZjdlUlZlRkJWblZuMWFieEl4cWwzazViQ3ZFYmZWNmxx?= =?utf-8?B?cmhhRzFkRERhenF3UW15SDdKSzFJMU5sQVJWR2NHbHlVL0JCTDlxSUE3L2Zq?= =?utf-8?B?K3p3Q2dFaE1JYVJYaWxyenYyUDZsdml4K2E3TlMra3BTNVJkQUtGeldRRUIv?= =?utf-8?B?elVIR3pvUzZ5YTkybTU5TVB5bGZ4S3J3cTVTK2hMVWFlRmgrdmdnM3pXMEg3?= =?utf-8?B?MFlLQW85TlpxTG9ra21DbmlxcnNjaUV6L1BsazhOWng0Ni9CUXZXVzdVUVRC?= =?utf-8?B?bFFpV2dsbVVDK25RQ3lYYXBvbjE2YjUwTnlMa0dpVXBaemJCQStJMGEwT2Vs?= =?utf-8?B?YTBBWnUvR1dUZEx1N2tFK3REb0NiNFc3OUQrRDY5STNlOWsvMXZSTURFZ1Iw?= =?utf-8?Q?aywm1s16LY+8s?= X-Microsoft-Exchange-Diagnostics: 1;BL2PR15MB0961;6:7yIDa/Do/THF0WmG/ig+iMvxxQml549wcVSNLsD4gj8aJVT9pWKi48hdQSl7yRbkfd3c2zsn+IpAMhIzyzXYQFDEPgP6c1GME+mIMmZehoc5eUmlDHalhs3cys2/JovnLvu2M1ppMG3NI0vkcoZhyEqkU0ocd3ZKkdjHKF2bYgwZ6CVewiZkNWA+9Q4jGEkL10nA80FsfEtT1G56/Jarp54xy/+z8fQnDMflRacWT5GXllAD+/ERvKWts+SfLUfT6xzEnCoaQBDZznFXkOS5rUL6vPlxEG8ZWPAPk3txLtZ2XyJMd6uYrqhS6QLJb7Duke1+ODl9fvdapoAk0W4QPwyxoQIRZTDwTeRaCTrcDpA=;5:f6VvdAXnKyTbGKbmmq5DKIgW1GVNl6Brw89zleLjvhxZ6tQWl2cLnidh1re5lDHdyO5f4zIiqRvmYXA9kViOtnolcUmchmXAtPpkddP6VDv62IpIaREUOOslufAy3adZzz3rXEA8Jl+Ax7rbxUgbXhDzfgSSpIVYH4azuHiaaPI=;24:4liLO7I0S7Wcu6EVYyXekXd6Iizm1k+3RA+gX+AyEgrmEhpr7+rLAzeXiAUHTsV8in+YlBwqOseRVgiOG0q2lx5ZPwU9LTK1xvf52yMOKzc=;7:439cERteqDLzGcE6wS9WzpUr5byIaJuSVelh7ldaed9kykvptGE35U7cTIuWfeNSumOwnfDBqNRgCDtBlx1QlcIkEXCaWzWPo2pbD8K/ix9+K2ySzidi/5UHmmOlflD724ngUpnv+BNX9+JLaTTZUfXiQa87dn6CloD90/J6EyxvKG3xy7grYzpnhnlNnhkIm/K7MJBAybSwn5UA3VcMIomC8XSxSLcFU4awmJAXPici8TEebc4Mxgtix2EiqWTD SpamDiagnosticOutput: 1:99 SpamDiagnosticMetadata: NSPM X-Microsoft-Exchange-Diagnostics: 1;BL2PR15MB0961;20:iJUBz/FmhOSL1zqM63Ufz/b26Pm4eWJQqpl1pZr/jI88uT8qK3/hIO44oxy9KnnVNvdhNbFp8O3mgqpZR+LBCkxaLmoRrdpen3XugAvnwWIb3T/3bm7nHIjn0BtARdmf2VPfLzxmPhn1nWSfa1oX2FrI7DnktNcqwNERQSze7qA= X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Nov 2017 22:04:21.0058 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: a431223b-07bf-4c6c-e788-08d5262b81cd X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL2PR15MB0961 X-OriginatorOrg: fb.com X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-11-07_07:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/8/17 6:47 AM, Y Song wrote: > On Tue, Nov 7, 2017 at 1:39 PM, Alexei Starovoitov wrote: >> On 11/8/17 6:14 AM, Y Song wrote: >>> >>> On Tue, Nov 7, 2017 at 12:37 AM, Naveen N. Rao >>> wrote: >>>> >>>> Alexei Starovoitov wrote: >>>>> >>>>> >>>>> On 11/7/17 12:55 AM, Naveen N. Rao wrote: >>>>>>> >>>>>>> >>>>>>> I thought such struct shouldn't change layout. >>>>>>> If it is we need to fix include/linux/compiler-clang.h to do that >>>>>>> anon struct as well. >>>>>> >>>>>> >>>>>> >>>>>> We considered that, but it looked to be very dependent on the version >>>>>> of >>>>>> gcc used to build the kernel. But, this may be a simpler approach for >>>>>> the shorter term. >>>>>> >>>>> >>>>> why it would depend on version of gcc? >>>> >>>> >>>> >>>> From what I can see, randomized_struct_fields_start is defined only for >>>> gcc >>>>> >>>>> = 4.6. For older versions, it does not get mapped to an anonymous >>>> >>>> structure. We may not care for older gcc versions, but.. >>>> >>>> The other issue was that __randomize_layout maps to __designated_init >>>> when >>>> randstruct plugin is not enabled, which is in turn an attribute on gcc >= >>>> v5.1, but not otherwise. >>>> >>>>> We just need this, no? >>>>> >>>>> diff --git a/include/linux/compiler-clang.h >>>>> b/include/linux/compiler-clang.h >>>>> index de179993e039..4e29ab6187cb 100644 >>>>> --- a/include/linux/compiler-clang.h >>>>> +++ b/include/linux/compiler-clang.h >>>>> @@ -15,3 +15,6 @@ >>>>> * with any version that can compile the kernel >>>>> */ >>>>> #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), >>>>> __COUNTER__) >>>>> + >>>>> +#define randomized_struct_fields_start struct { >>>>> +#define randomized_struct_fields_end }; >>>>> >>>>> since offsets are mandated by C standard. >>>> >>>> >>>> >>>> Yes, this is what we're testing with and is probably sufficient for our >>>> purposes. >>> >>> >>> Just tested this with bcc. bcc actually complains. the rewriter >>> is not able to rewrite prev->pid where prev is "struct task_struct *prev". >>> I will change bcc rewriter to see whether the field value is correct or >>> not. >>> >>> Not sure my understanding is correct or not, but I am afraid that >>> the above approach for clang compiler change may not work. >>> If clang calculates the field offset based on header file, the offset >>> may not be the same as kernel one.... >> >> >> why is that? >> When randomization is off both gcc and clang must generate the same >> offsets, since it's C standard. > > The patch changed compiler-clang.h, so gcc still do randomization. gcc_plugins are off by default and randomization will not be turned on for any sane distro or datacenter that cares about performance and stability. So imo above compiler-clang.h patch together with bcc fix would be enough.