From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4B77FCD4F3D for ; Fri, 22 May 2026 22:33:06 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 56B186B0096; Fri, 22 May 2026 18:33:05 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5116E6B0099; Fri, 22 May 2026 18:33:05 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4002E6B009B; Fri, 22 May 2026 18:33:05 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 2FCCA6B0096 for ; Fri, 22 May 2026 18:33:05 -0400 (EDT) Received: from smtpin10.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 6B6B21C06F9 for ; Fri, 22 May 2026 22:33:04 +0000 (UTC) X-FDA: 84796507488.10.5E9F6E9 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf12.hostedemail.com (Postfix) with ESMTP id AB72140005 for ; Fri, 22 May 2026 22:33:02 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=Dkx8nkhm; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf12.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1779489182; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=VRX6RdQlInnC8iDYrg/+evNFCkJuEZSlotJ8IHNu/Y0=; b=c4goTvJdr4RSI98eL1qsf/35nG4h6wYhGL2a5XfaI72MSE3/4MdLhhcdymb7WB2bwh/kmr xL+/88SsGyjCUQzSBxnJ9/AvhxqUnQ+cb1juEBE96R5fB7aIJzpQTjJLFF5BOIOoGdN8xL azJlU5iEwrHppBNKBFLGTZuaq0AmrV0= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=Dkx8nkhm; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf12.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1779489182; a=rsa-sha256; cv=none; b=5uyHuTIdCOmWdEcV01FYmBHppmQr11hPlcXtNnU/x1M1HCXMRIqH4mrrENg4MW7jGLGkKD OO+UgZuswmFJ0ECBaJ6ICqrCD8oGTo/3VfGdsJOVGTsoliuQgA/26tMHj3R8gjRs85UFTr RkwQwB/TDq4ZGL/YVUR024FutyoaW6Y= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 0A0BA60103; Fri, 22 May 2026 22:33:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 306B01F000E9; Fri, 22 May 2026 22:32:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779489181; bh=VRX6RdQlInnC8iDYrg/+evNFCkJuEZSlotJ8IHNu/Y0=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=Dkx8nkhm71/jfiQYcLtXj5OCx+u+h077LFH9Ejt8Sn588F4qJil9eyTGHRRwI0Q/d fHpcbCxFp5UbSV3lR+9duxR/W5vBjEFXF3fJ7rQBy/y521MQK7HcPyXeKfjT3Ud0/+ mHzLBFrT8K8crdEq5tv8JmRqoqebcuwktqeCYwPQE9oaNnD779704BCvdsKQLsqZXs s6tr6VoMLrVVgHztbhW1ylZ9tFUO4cuaU/Rit2HF/PpME+S5yiGaopQn1s+7IVQ1Y1 T8yZ/XNZJJq027DqDU+YYOXTfGczEkcri/q6YyAQzS7uXDh+k8ETDb3W+uka5TAoSk 4Yj2ZbF4s8IKQ== Message-ID: <610c0702-4e55-429f-befd-445134483563@kernel.org> Date: Sat, 23 May 2026 00:32:56 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC v3 3/4] ptrace: add ptracer_access_allowed() To: "Christian Brauner (Amutable)" , Jann Horn , Linus Torvalds , Oleg Nesterov Cc: Andrew Morton , Qualys Security Advisory , Kees Cook , Minchan Kim , linux-mm@kvack.org, Suren Baghdasaryan , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Michal Hocko References: <20260520-work-task_exec_state-v3-0-69f895bc1385@kernel.org> <20260520-work-task_exec_state-v3-3-69f895bc1385@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20260520-work-task_exec_state-v3-3-69f895bc1385@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: AB72140005 X-Stat-Signature: jzf1hgi8fmi7ixkgawcdpc3cerqh8du3 X-Rspam-User: X-HE-Tag: 1779489182-407701 X-HE-Meta: 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 Jb+zpAKW PFwBxq6d5FJgAq6THtvBSKlO/uqODJq8snZdrVg0tch4ePRGyJFE+MfgVAnJHdQ7wncdK2zo5uREcFHfFNNkatVnz9hWQmqGRty4jgLlbxPXGIRWOdRZCbgrAPFEO2UddPInCY4/yN7ueM6F+Pm07rZLfWC9vkhzEe5qqg3JmxHQB6YQY/fIyE/QA3PkOOwRwHTAVio55rW/aIPHU7lriI90zwMW2OgXZzdfE1k9xcgXUHb8ppXCdNBnU8gjwQ0UtCXlCvL9jgKk7aWwKcs0nVRb4Py9b6Ie5CIvsUmCR+ktne5C1ncoCeY9UFAZG2uho8FlUrnRc4PUCGJlP6+IE1J7KTtc4CKGqnsTne2QkcgmN9aWCDMD5fLpiRvK9UAJdOcUF Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 5/20/26 23:48, Christian Brauner (Amutable) wrote: > Add a helper that encapsulates all of the logic for checking ptrace > access and remove open-coded versions in follow-up patches. > > Reviewed-by: Jann Horn > Signed-off-by: Christian Brauner (Amutable) > --- > include/linux/ptrace.h | 1 + > kernel/ptrace.c | 27 +++++++++++++++++++++++++++ > 2 files changed, 28 insertions(+) > > diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h > index 90507d4afcd6..ef314f7a9ecc 100644 > --- a/include/linux/ptrace.h > +++ b/include/linux/ptrace.h > @@ -17,6 +17,7 @@ struct syscall_info { > struct seccomp_data data; > }; > > +bool ptracer_access_allowed(struct task_struct *tsk); > extern int ptrace_access_vm(struct task_struct *tsk, unsigned long addr, > void *buf, int len, unsigned int gup_flags); > > diff --git a/kernel/ptrace.c b/kernel/ptrace.c > index 07398c9c8fe3..0e1f80f73a7f 100644 > --- a/kernel/ptrace.c > +++ b/kernel/ptrace.c > @@ -13,6 +13,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -36,6 +37,32 @@ > > #include /* for syscall_get_* */ > > +/** > + * ptracer_access_allowed - may current peek/poke @tsk's address space? > + * @tsk: tracee > + * > + * Per-access check used by ptrace_access_vm() and architecture-specific > + * tag/register accessors. Returns true iff current is the registered > + * ptracer of @tsk and either @tsk is owner-dumpable or current holds > + * CAP_SYS_PTRACE in @tsk's exec namespace. Lighter than > + * __ptrace_may_access(): it re-validates only dumpability and > + * capability on every access, without re-running LSM hooks or > + * cred_cap_issubset() checks performed at attach time. > + */ > +bool ptracer_access_allowed(struct task_struct *tsk) > +{ > + const struct task_exec_state *es; > + > + if (!tsk->ptrace) > + return false; > + if (current != tsk->parent) > + return false; > + guard(rcu)(); > + es = task_exec_state_rcu(tsk); > + return READ_ONCE(es->dumpable) == TASK_DUMPABLE_OWNER || > + ptracer_capable(tsk, es->user_ns); > +} > + > /* > * Access another process' address space via ptrace. > * Source/target buffer must be kernel space, > Besides the new RCU + old MM handling, this matches what we do in ptrace_access_vm(). Reviewed-by: David Hildenbrand (arm) -- Cheers, David