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 18F8FCD4F3D for ; Wed, 20 May 2026 21:49:19 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 77DF96B0092; Wed, 20 May 2026 17:49:18 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 72F036B0095; Wed, 20 May 2026 17:49:18 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 61D936B0096; Wed, 20 May 2026 17:49:18 -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 550986B0092 for ; Wed, 20 May 2026 17:49:18 -0400 (EDT) Received: from smtpin26.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 0637A8D1FE for ; Wed, 20 May 2026 21:49:18 +0000 (UTC) X-FDA: 84789139596.26.ECBE9FD Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf26.hostedemail.com (Postfix) with ESMTP id 4580F14000A for ; Wed, 20 May 2026 21:49:16 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=GWOdtwhE; spf=pass (imf26.hostedemail.com: domain of brauner@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=brauner@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1779313756; 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=lrJdT5/Hkn1JInBKx8um+ZwIQJoC7T3gsIrsOIlTpJQ=; b=stOwmVFFMx5puv8NVPsG25S61uE6eZBIpgThFm1eirsyUiR9YqFnbBv2jJbdSnoUaex/6Y QliRfMssBLR53XrQo2XBQsSaogS1b9iQT5TfgEFseEZwWuflaAGBJ9EyUX3ctpdktf/LEL BtLNbmdJ6rtWkKmYu8O7MiaGWuXAnbU= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1779313756; a=rsa-sha256; cv=none; b=uqsj3QZDvJWGa3/qdXrTI6LjdtapJxtaBpQ+TgxQkPZDNpc4Wfe2lbVjuw7CAXahetwta2 UuFluWE/627g8LYsKdF4ZoryRSTIvrrBhrWdl1HoPLPiP0PBDLXmB+qvAWdq0JaIsyeqjl JHBGcVIOwuqaAEUAe1lTetCkTgHbjFg= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=GWOdtwhE; spf=pass (imf26.hostedemail.com: domain of brauner@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=brauner@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id C41D2600FF; Wed, 20 May 2026 21:49:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 140881F000E9; Wed, 20 May 2026 21:49:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779313755; bh=lrJdT5/Hkn1JInBKx8um+ZwIQJoC7T3gsIrsOIlTpJQ=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=GWOdtwhEiy+Ywq1F0bATocbsaAD71rz+YlBhQrPH97jU5m9LKaUUygKqqT0FVRWgO lv3UPcQJ18geFm0APZ+kbmdcP+ICinicjB3v5Rf14a8x4gUnNOaIMXeylsFzf3Vr7E Yrrn0GQvz43CtBvfjG1Hs17AhSWKEUp26N8zFsi91B/LZEi39jMf3wlXtEoFq1FxCe J22w3rc3gprAibaH9a3LWc3bPqLuAqZXDwcTLlL+02DAWjyDNqtyNsx97+2Q/xT0RW KR7m7iZ9Dqf6cm/GdAeLx+9XzFCLouS+JGoXtFt4VtYgJKlBeK8lZfmH55Wtcozt96 g+JklGDnUFXJw== From: "Christian Brauner (Amutable)" Date: Wed, 20 May 2026 23:48:54 +0200 Subject: [PATCH RFC v3 3/4] ptrace: add ptracer_access_allowed() MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260520-work-task_exec_state-v3-3-69f895bc1385@kernel.org> References: <20260520-work-task_exec_state-v3-0-69f895bc1385@kernel.org> In-Reply-To: <20260520-work-task_exec_state-v3-0-69f895bc1385@kernel.org> To: Jann Horn , Linus Torvalds , Oleg Nesterov Cc: "David Hildenbrand (Arm)" , 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 , "Christian Brauner (Amutable)" X-Mailer: b4 0.16-dev-d5d98 X-Developer-Signature: v=1; a=openpgp-sha256; l=2298; i=brauner@kernel.org; h=from:subject:message-id; bh=W8K5dO9D9mrOIuLfw9lrPq4XuIDQC4pNK8UxrFpZggQ=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWTx6Xhrnu2TWPSEee+xYnmD2GXVEj1SbYklfX6e3rPzb ndc2Liko5SFQYyLQVZMkcWh3SRcbjlPxWajTA2YOaxMIEMYuDgFYCLPxRgZHvCWduTWJWybLVL8 W/9Jwe8L7AKHmDyXC7k6GamcO/x3AyND3wQzlZDdwn/rZ4ScPuOmdFlU5NK1YL7Vx03FXrcHiNx jBAA= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 X-Rspam-User: X-Rspamd-Queue-Id: 4580F14000A X-Stat-Signature: bzz1fcby6tetbcbmwsghjgxqg94m8nyo X-Rspamd-Server: rspam06 X-HE-Tag: 1779313756-11446 X-HE-Meta: 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 /sM6CoRD dlAiRSUF8TrBNvu8zWO6yDc8oUBDEeMoLL0+Z6O4CEn9jeKjFjtiKEcdF86ZmtuYkFqywM9Prd2uoLB1qsD42qcEFitbbgYTQnF2FG0VhFG46QfeMb4u0ymdrDmKd+XIRjpi3I6ePh83s1nPgNXxg8PbPVVKFxdCH8+++C+y+s3f4orMinVcPABmf8tskvv0ClsTfujFYt9Z2Ldd3SKGJob93ubwuuirVvjYC8UPEwbiBomVBhq7Y4VyCVx5ZuLzJifggS6mNILHFwb6mfsI8KuUdz8yPA3u54Ne2wDC31/LrNKVeYyeeizu5ranZb0+37tWFQoxIsRKvmomwuRPF9WmeqhIE9duEHBHH Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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, -- 2.47.3