From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0B591316199 for ; Tue, 15 Sep 2026 01:08:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789434538; cv=none; b=GYP+jBkuttq8gxNS/AEjHNFPPO+z2wA4M6BQcYU4L90a5YHfrhdY+ERX53ZoCxxMLoKaZ+2H2gXc1Z4RlXYgNGKvf3IO0k7PWYucMd94jX5mEq/lnlAduJZ5bZ6Qik1LTEEAVXH+B7MVqQT+d4HGlwgvUvk3AQIb42AbdT8WmQg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789434538; c=relaxed/simple; bh=sI5ym07NWdG3tmFbIBDjBbi3Qv0BXLy0lrkO/ei5yCg=; h=Date:To:From:Subject:Message-Id; b=K8ZVfG82HAxk1p6KmApNBqB1YfhUIKdsnknJfr9+DN3tHZX8k9wZJ/n7Ew6dVQTGMaHlyhCWgLo2AFqarqCWq1cPQhLkLC3avKSokdMaQ5waTb1dp4ZbWdzSZVYWGPIlzaBcPCgMcMKPYXMm0c21mTFXgYo3PvkTQAhrfnr3mMA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=yAIYbPiU; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="yAIYbPiU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CC0A51F000FF; Tue, 15 Sep 2026 01:08:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1789434536; bh=PJgv087VirHIbcU8kSvML3YsvG3bkE64CoIA69DiNAg=; h=Date:To:From:Subject; b=yAIYbPiUcu9/Z9O1saBkXC1cnVCI0YFvErG+fTcCNACNrWZw/p7JG5CuN6W6IrV9m 2iOVOG32RXmxDSjoi1xIuz5c8yfClQB1K2+4gW0MyB7gEzaCsXdjXdaudaVUX2kmQI qPs4apCTyzD2TDuoOxzEmD8zaj+Q4tR9DSjkXepo= Date: Mon, 14 Sep 2026 18:08:56 -0700 To: mm-commits@vger.kernel.org,stephen.smalley.work@gmail.com,jannh@google.com,ljs@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: + selinux-reject-writable-opens-of-policy-file-drop-mmap-shared-write-check.patch added to mm-new branch Message-Id: <20260915010856.CC0A51F000FF@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: selinux: reject writable opens of policy file, drop mmap shared/write check has been added to the -mm mm-new branch. Its filename is selinux-reject-writable-opens-of-policy-file-drop-mmap-shared-write-check.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selinux-reject-writable-opens-of-policy-file-drop-mmap-shared-write-check.patch This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. The mm-new branch of mm.git is not included in linux-next If a few days of testing in mm-new is successful, the patch will me moved into mm.git's mm-unstable branch, which is included in linux-next Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: "Lorenzo Stoakes (ARM)" Subject: selinux: reject writable opens of policy file, drop mmap shared/write check Date: Mon, 14 Sep 2026 15:57:32 +0100 The policy file has no write method and is exposed read-only (S_IRUGO in selinux_files[]), yet sel_open_policy() performs no open mode check, so a CAP_DAC_OVERRIDE caller can open it O_RDWR. Reject FMODE_WRITE at open, as kernfs does. The file can then never be mapped with FMODE_WRITE, so do_mmap() always clears VM_MAYWRITE and VM_SHARED for MAP_SHARED mappings and the VM_SHARED check in sel_mmap_policy() cannot be reached. Remove it. This also stops sel_mmap_policy() clearing VM_MAYWRITE on a mapping that is neither a PFN map nor a mixed map, ahead of the core enforcing that only such mappings may do so. Link: https://lore.kernel.org/20260914-b4-mmap-prepare-vma-flag-sanify-v2-12-7d9781ed5361@kernel.org Signed-off-by: Lorenzo Stoakes (ARM) Signed-off-by: Andrew Morton Acked-by: Stephen Smalley Reviewed-by: Jann Horn --- security/selinux/selinuxfs.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) --- a/security/selinux/selinuxfs.c~selinux-reject-writable-opens-of-policy-file-drop-mmap-shared-write-check +++ a/security/selinux/selinuxfs.c @@ -340,6 +340,9 @@ static int sel_open_policy(struct inode struct policy_load_memory *plm = NULL; int rc; + if (filp->f_mode & FMODE_WRITE) + return -EACCES; + rc = avc_has_perm(current_sid(), SECINITSID_SECURITY, SECCLASS_SECURITY, SECURITY__READ_POLICY, NULL); if (rc) @@ -424,14 +427,6 @@ static const struct vm_operations_struct static int sel_mmap_policy(struct file *filp, struct vm_area_struct *vma) { - if (vma->vm_flags & VM_SHARED) { - /* do not allow mprotect to make mapping writable */ - vm_flags_clear(vma, VM_MAYWRITE); - - if (vma->vm_flags & VM_WRITE) - return -EACCES; - } - vm_flags_set(vma, VM_DONTEXPAND | VM_DONTDUMP); vma->vm_ops = &sel_mmap_policy_ops; _ Patches currently in -mm which might be from ljs@kernel.org are mm-vmpressure-remove-window-size-todo.patch tools-testing-selftests-mm-add-missing-gitignore-entries.patch mm-move-drivers-char-memc-to-mm-char-memc.patch mm-implement-file_is_dev_zero-to-uniquely-identify-dev-zero.patch mm-vma-only-permit-map_private-dev-zero-to-be-mapped-anonymous.patch mm-vma-make-map_private-mapped-dev-zero-mappings-truly-anonymous.patch tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon.patch tools-testing-selftests-mm-add-map_private-dev-zero-merge-tests.patch mm-madvise-swap-in-cowd-map_private-file-mappings-on-madv_willneed.patch mm-huge_memory-zap-deposited-page-tables-after-an-rcu-grace-period.patch mm-enable-mmu_gather_rcu_table_free-for-most-2-level-architectures.patch mm-enable-mmu_gather_rcu_table_free-for-mmu-riscv.patch mm-enable-mmu_gather_rcu_table_free-for-mmu-arm.patch mm-enable-mmu_gather_rcu_table_free-for-arc-microblaze-xtensa.patch mm-enable-mmu_gather_rcu_table_free-for-sparc64.patch mm-enable-mmu_gather_rcu_table_free-for-m68k-coldfire.patch mm-enable-mmu_gather_rcu_table_free-for-sh-x2.patch mm-enable-mmu_gather_rcu_table_free-for-m68k-motorola.patch mm-enable-mmu_gather_rcu_table_free-for-sparc32.patch mm-make-userland-page-table-freeing-rcu-safe.patch mm-change-the-contract-for-free_pgtables-update-docs.patch mm-vma-fix-mmap_prepare-file-handling-remove-file_doesnt_need_get.patch mm-vma-predicate-setting-mmap_prepare-vma-fields-on-new-vma-alloc.patch mm-vma-introduce-and-use-vma_can_merge.patch mm-consistently-validate-vma-state-after-mmap-hooks.patch mm-vma-ensure-mmap_prepare-doesnt-set-actions-on-a-mergeable-vma.patch mm-make-map_kernel_pages_-internal-and-unexported.patch mm-vma-tidy-up-map-kernel-pages-enum-values.patch mm-add-mmap-action-for-discontiguous-kernel-page-mapping.patch docs-filesystems-update-mmap_prepare-docs-for-discontig-kernel-pgs.patch drivers-usb-mon-update-to-use-mmap_prepare-map-kernel-pages.patch infiniband-update-hfi1-to-use-remap_vmalloc_range.patch selinux-reject-writable-opens-of-policy-file-drop-mmap-shared-write-check.patch alsa-pcm-use-vm_insert_page-to-map-pcm-status-page.patch bpf-arena-mark-arena_map_mmap-mappings-vm_mixedmap.patch mm-vma-add-vma_is_kernel_owned-predicates.patch mm-vma-only-allow-mmap-to-clear-vma_maywrite_bit-if-kernel-owned.patch mm-vma-add-and-use-vma__is_fixed_mapping.patch scsi-sg-convert-mmap-hook-to-mmap_prepare-and-rework.patch fbdev-defio-assert-fbinfo_virtfb-drop-vm_io-add-vm_mixedmap.patch hsi-cmt_speech-convert-mmap-hook-to-mmap_prepare-refactor.patch mm-gup-error-out-early-on-vma_mayread_bit-vmas.patch uprobes-remove-vm_io-set-vm_mixedmap-for-mapped-kernel-pages.patch mm-mlock-clear-vma_locked_mask-over-mmap-callback.patch mm-mlock-eliminate-weird-vma_io_bit-abuse-and-simplify.patch mm-vma-enforce-that-only-kernel-owned-mappings-may-set-vma_io_bit.patch mm-remove-vma_io_bit-check-in-vma_is_kernel_owned.patch mm-remove-hugetlb_inlineh.patch mm-rename-is_vm_hugetlb_page-to-vma_is_hugetlb.patch mm-drop-some-redundant-checks-around-hugetlb-vmas.patch mm-madvise-update-is_valid_guard_vma-to-use-vma_can_merge.patch mm-vma-introduce-vma_is_persistent.patch mm-uffd-use-predicates-for-userfaultfd-checks.patch mm-madvise-use-predicates-for-madvise-madv_dofork.patch mm-eliminate-vma_special_flags-usage-when-hugetlb-explicitly-tested.patch mm-eliminate-vma_special_flags-check-in-lru_gen_look_around.patch mm-avoid-use-of-vma_special_flags-in-migrate_vma_setup.patch mm-eliminate-vm_special-vma_special_flags.patch fuse-dax-do-not-set-vm_mixedmap.patch mm-huge_memory-remove-vma_is_special_huge.patch mm-vma-introduce-and-use-vma_can_gup.patch