From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f53.google.com (mail-wm1-f53.google.com [209.85.128.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 16D9952FE46 for ; Tue, 8 Sep 2026 13:53:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.53 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788875644; cv=none; b=IBoeDPbkeRF5B+s992W25Syy0tCq9zoJndSZpmqrQXmxv+1URJMyTpZ68RtHiIAmmFoykPF0xEBUA8XE/TEcBLw/idjrVUViGaTWPlckn/Kz2YNy0HDLEzLWNpTpxN3aFT+SOY9MlpSs0FOl7gEfWTR6eTuoVlNGJ5Le1bJTtaM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788875644; c=relaxed/simple; bh=nn6iDL8B9k+PR6cXXKfLJz/cPg/XodyTbC68/H77o/k=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Wyyg/YkcOjLYTYI4W4pb+nQH2vSKWtKQOEE9OX0roLDfBa8Q7obXfwaunbaZzZCRujxYIGGr5x7ViXLKgfMS3JtxdBdU02rWFbKFx+e2kZU9Cf1eu0/wZsCV4LzkJrAWJuzSpv6u/Pl8Apm8am9q0Ieo+7AhkE7TLMadtWMphPI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=OmEdKU6F; arc=none smtp.client-ip=209.85.128.53 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="OmEdKU6F" Received: by mail-wm1-f53.google.com with SMTP id 5b1f17b1804b1-49954b88fffso34597455e9.0 for ; Tue, 08 Sep 2026 06:53:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1788875626; x=1789480426; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=EkB8DRl1+/pAks8Eb/LLAKOiFOjTpgaq+26U4zD1T/Y=; b=OmEdKU6FFfX3cTa3ls6LLkUB8mwlzpWVRknNJQPZ/X2keZku5/s8ry1o9zd57mYitL XsLehqLvUHpnRReQIJtNlh2J9kuMKD6Bg3qSuA7jLcTOblSMUnrF2tDUlZTIGdap2FyB l8h9XCEeQg/Y60hCdatflWmzMqhVopXvdHtHoyVd44EhRnSzsFuWzx55YTBuGl1jtZl7 QMUEFj5PQ6nsi9vPEcf/MhKvvTTSg//A6Ic8zu0b/5LhyLIfxrEC7edGeEfKOWB/1At2 p03jcq/oL3zaSRHCC/rAauQtbCDIPu3MZBUeGOZr4y8LalORiJ+coVjdHQdDgGtLTP1c Lklw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788875626; x=1789480426; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=EkB8DRl1+/pAks8Eb/LLAKOiFOjTpgaq+26U4zD1T/Y=; b=FodEtD7Yl0dByg8S99biTSDrT+dPB7vaFPd9HuPH+I0AH0aVhIE3VG80pKCU8mNJqx UQiUs8wBzBAmcDTxYibiaEHioN2eMXh9Gc0ND7Jks0/Fecgqz/Zg51wKO/z4idtP1+2V ssJGxiaXjCZbX50KuQ4J59t9TCGiQkY1fzNHLHcVHoUcvk5GZ/wlsv8kOmY4h5jENbXD zcA9EehiDs3xJsyGC58Z//F9/puR5fu8ZOqhvulY4RNQo75NzkVAhxYyhQ7tANStgJIa c6feAiWIKUQcOfE4GMytuEvJSON/0/n10opQeZ6SGkgj2eaMTW8+s2H3RnS5J0J0lsPH AHPQ== X-Gm-Message-State: AFuF++kTmuw1WDEuW113gEXBTOIFOTJXYjKMMbG2L9sz+zxt/z7ipNip YeK5dgeGfPtFL1V/4kzd8v44kPG3SX+7sZgne4t4Z4vARIDQeDUAA/mD X-Gm-Gg: AYBFou1+XNMShA8RD+GshXj5UVQFZtxAK5eKo3hBgNZ0iz3C2BV39DvM+JdL0SLUZb4 1ggZkziQ3+5ZMkeZ/6OTn/r7d9dvuxjC6B6pudQHi++OfchPn21u797rgH8WrK7rQ7ucOyOC4Zk QvL9FEuhSsgwvv3VIUxUJd7D4awuuicKtbFMyftxTFOh5rjfR+ubbK9NBwPdDHWfQHiZtYYCKeY soA29SkWW6XChIk14PZ9zS6XWzowBXOzElua8O//f5sUm5BaiH9pGw/3lxjaE4DwScp8IXeeKqI au0NNydkAoQwWDnqRdIuNOc3hJdRD/kC0wDCTha58GElzpFcWSXo6vFXZ51wjO+nu5u41yvOmwj OcfLeqM1qhOSpM6U26DVVL4/4U+EPjKdL/+vN8t8/QabsyBEp06AkGjQHZkQ+mMU0rEZjulZthw oiCr4r7wRMSO2i1rhlu6OR45s1fBa//Xusfqk6bCbCbmw2+XJW2T9NyjFcG/f95q2IKpDIkfw8Q A5w6zyAjgqL X-Received: by 2002:a05:600c:34ca:b0:49c:ee36:10fc with SMTP id 5b1f17b1804b1-49cf820e13bmr281314635e9.8.1788875625455; Tue, 08 Sep 2026 06:53:45 -0700 (PDT) Received: from dell-desktop ([2a02:587:4b5f:900:ef25:2f4:1792:4e6f]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49ce5533ffbsm377235005e9.3.2026.09.08.06.53.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Sep 2026 06:53:45 -0700 (PDT) From: Anastasios Papagiannis To: bpf@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, david@kernel.org, akpm@linux-foundation.org, andrii@kernel.org, ast@kernel.org, brauner@kernel.org, daniel@iogearbox.net, eddyz87@gmail.com, kpsingh@kernel.org, ljs@kernel.org, matt@bobrowski.net, memxor@gmail.com, song@kernel.org, sun.jian.kdev@gmail.com, utilityemal77@gmail.com, viro@zeniv.linux.org.uk, tasos.papagiannnis@gmail.com Subject: [PATCH bpf-next v6 4/5] bpf: Mark linux_binprm->mm as trusted-or-null Date: Tue, 8 Sep 2026 16:53:01 +0300 Message-ID: <20260908135302.74963-5-tasos.papagiannnis@gmail.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260908135302.74963-1-tasos.papagiannnis@gmail.com> References: <20260908135302.74963-1-tasos.papagiannnis@gmail.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Mark linux_binprm->mm as a trusted-or-null nested pointer so BPF programs can pass it to kfuncs after a NULL check. The field is either NULL or points to a live mm_struct whenever BPF can access a linux_binprm. On successful exec, exec_mmap() installs the new address space before begin_new_exec() clears bprm->mm. The bprm_mm_init() error path clears the field before mmdrop(), and free_bprm() clears it before mmput(), as ensured by an earlier patch in this series. Update the existing LSM selftest to check bprm->mm for NULL before dereferencing it, as required for trusted-or-null pointers. Signed-off-by: Anastasios Papagiannis Reviewed-by: Sun Jian Reviewed-By: Matt Bobrowski --- kernel/bpf/verifier.c | 5 +++++ tools/testing/selftests/bpf/progs/lsm.c | 5 ++++- 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 9e79750e2480..791b3d25caa5 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6004,6 +6004,10 @@ BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct dentry) { struct inode *d_inode; }; +BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct linux_binprm) { + struct mm_struct *mm; +}; + BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct socket) { struct sock *sk; }; @@ -6058,6 +6062,7 @@ static bool type_is_trusted_or_null(struct bpf_verifier_env *env, { BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct socket)); BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct dentry)); + BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct linux_binprm)); BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct vm_area_struct)); return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, diff --git a/tools/testing/selftests/bpf/progs/lsm.c b/tools/testing/selftests/bpf/progs/lsm.c index 7de173daf27b..7441d66c080c 100644 --- a/tools/testing/selftests/bpf/progs/lsm.c +++ b/tools/testing/selftests/bpf/progs/lsm.c @@ -113,6 +113,7 @@ int BPF_PROG(test_void_hook, struct linux_binprm *bprm) { __u32 pid = bpf_get_current_pid_tgid() >> 32; struct inner_map *inner_map; + struct mm_struct *mm; char args[64]; __u32 key = 0; __u64 *value; @@ -121,7 +122,9 @@ int BPF_PROG(test_void_hook, struct linux_binprm *bprm) bprm_count++; bpf_copy_from_user(args, sizeof(args), (void *)bprm->vma->vm_mm->arg_start); - bpf_copy_from_user(args, sizeof(args), (void *)bprm->mm->arg_start); + mm = bprm->mm; + if (mm) + bpf_copy_from_user(args, sizeof(args), (void *)mm->arg_start); value = bpf_map_lookup_elem(&array, &key); if (value) -- 2.55.0