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 557DDCD4F3D for ; Wed, 20 May 2026 14:43:34 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BDD866B0095; Wed, 20 May 2026 10:43:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BB54A6B0096; Wed, 20 May 2026 10:43:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AF22A6B0098; Wed, 20 May 2026 10:43:33 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 9E7676B0095 for ; Wed, 20 May 2026 10:43:33 -0400 (EDT) Received: from smtpin28.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 6E53FA0388 for ; Wed, 20 May 2026 14:43:33 +0000 (UTC) X-FDA: 84788066706.28.62FFFC3 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf10.hostedemail.com (Postfix) with ESMTP id 7E1B4C0006 for ; Wed, 20 May 2026 14:43:31 +0000 (UTC) Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=npDbjlIN; spf=pass (imf10.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=1779288211; 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=cA8jfZ0PItYW2mi5IdBqTPaBnduDIHyksLZMvz7bUxU=; b=HNqNWvC1wpVgbwl8MrZIOAGDYsh183mP8r3QhlzCcV1GfaR8tdabN+DF52ltTvTIuaYgZL 0kbyHo4FIyhWvqRRWFc6B6uxY1GldqAwroqw2xFo28b463CMsdPA3hAuxPWK3slElOFRjt nWc1dGq3m2JUy7UnuFyzYOdODdzMqxU= ARC-Authentication-Results: i=1; imf10.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=npDbjlIN; spf=pass (imf10.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-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1779288211; a=rsa-sha256; cv=none; b=lgtKczhh1s/NMIBBD0k97GdO+P+J6tcOazg72GJP6i3LKSvDYa8NJ3DmMmJbgMUMTIlqkW vsVjx2SUQOGJUud8TN7nmKhtTIHsrphF68dGMjUvb7vWmHNeYF3tAJkcC97GCCJ4/NXzmg ZUFyYHfJv55mI7/Zh0sNgcjfQ8P5t4w= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 1CDD560008; Wed, 20 May 2026 14:43:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4990E1F000E9; Wed, 20 May 2026 14:43:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779288210; bh=cA8jfZ0PItYW2mi5IdBqTPaBnduDIHyksLZMvz7bUxU=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=npDbjlINardW1b+wnW5ioc7Zt7LBZmOXDVkZ9pja5AWP5jb7GT8EH+W85F6sKDodb yu0Nqa8HHfFxNVyy0Wn+JkJANEo0WaqNh6tz1LT6U41utLP3RL8rTVBx1xTd41BmKl aq1GIwVFV4JiGrIyhy719h52S/AZkxmiWdx5le+4GEpH1LTCr3UAB6YzHeruLzBSpN Up8481llqTWA0nz3D4g3BkPL6PW1cefw8/tcT6pEsSJHpNyRFfxBbsoqcFjwduGSmA KNPV27hzkq7sFGi1HpPgf8DvSlFOqYpL7IcRHvzK/SzCSv4g2492leE3Ke9sTxwbq2 KKYMGppvTxtPg== From: Christian Brauner Date: Wed, 20 May 2026 16:42:56 +0200 Subject: [PATCH RFC v2 3/5] 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-v2-3-9ea88ceb09e6@kernel.org> References: <20260520-work-task_exec_state-v2-0-9ea88ceb09e6@kernel.org> In-Reply-To: <20260520-work-task_exec_state-v2-0-9ea88ceb09e6@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=2217; i=brauner@kernel.org; h=from:subject:message-id; bh=2a/Z2caovtOQVDYSymcMTRrhIMfnAjYOZKY2geq9AOI=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWTxnmg+rsvy8eT+jkiFrGPLU9V/XvsveKiZ9WbS+2t60 xXePOWt6ChlYRDjYpAVU2RxaDcJl1vOU7HZKFMDZg4rE8gQBi5OAZjIXk2G/9Xn3/TtejvH41rx VpaY74J2txrvRsdP77yRp+xzIUfo7EFGhou8ojt38Cy+4KX7f2n6Wsff/38m3X40tWhR/A5f694 jc9kB X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 X-Stat-Signature: d5q1s3aoztogxh7t7y5ekwotmm1yq1un X-Rspamd-Queue-Id: 7E1B4C0006 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1779288211-320780 X-HE-Meta: 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 at8vNIJn AbOBZl3ZfNF4oa1y1lepibNHKLv9AOlv8JFmzSSo+H2LN8fcgZkQVLg0eyjQdZAEYVnQMIHquamKksnrqyu4OyJJLgfW/1CoU/gTJWznLr35sXGCtdbezUUjWW8oH/tNoJwPm2jrcsLXKzJ/DgNDIGfoxsBljBLxgIzkHBemoNaAL2lNQLRcaZM7JrX8hPFEf0+9C/0Ub9DsYCt12MF1MpGz401+x9WSO/Bj/2KkotLVVxwz/dp5UCi0JoIak9XluVqhNm+YJzJFeIFEiqupWfMp3mAfPYRCsrR4t2lgV2lzzoE/uPJaBjQw68iadxemoQicc9OK5YgjKxnSsUfLaAkFZjiAeJ92KsU0MakyH6JRfWQo= 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. Signed-off-by: Christian Brauner (Amutable) --- include/linux/ptrace.h | 1 + kernel/ptrace.c | 26 ++++++++++++++++++++++++++ 2 files changed, 27 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..2dc7d01baba0 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -13,6 +13,7 @@ #include #include #include +#include #include #include #include @@ -36,6 +37,31 @@ #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. Stricter than the up-front + * ptrace_may_access() check at attach time; this re-validates on every + * memory access so privilege changes are observed promptly. + */ +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