From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 5EB9C3376BD; Tue, 26 Aug 2025 14:43:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756219435; cv=none; b=TpvhbxenWASbZ4f2ZZYKU2in+QPkvG/bytd0wcc+0hJW4+/xNySge6zRdzrNfwybkoyOGPA9lsSkqtAnIVm2106r0MDo8S+DGsGOnMh+Rxo5MEcgUaa9Sd1IoeXx+lfG323SlfE7sHe+ZUz2rzpEulw5SP0n5NY7GptQA4fYZMM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756219435; c=relaxed/simple; bh=9Ushf+NgKBvN0uNP6ljNqtv8uixSpOnVPMajbY67JhE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=mAunHAkigyqRhJlMMjkh7aeAjLsACdH4P4xb+VQlUwMP27WgWATq3FiZn7CqQMP62S/jYfnB5OO2x5BdHPW8V4kT3z+a4SUl5AceUIaRNfT+bDtZsOHl9Kglp/6aJh/KeXkrRDxnkN9wx4YOXwheVWzBM4eKzqBsgvTd+ot+a+M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=wrzC2RsT; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="wrzC2RsT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B3C52C4CEF1; Tue, 26 Aug 2025 14:43:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1756219435; bh=9Ushf+NgKBvN0uNP6ljNqtv8uixSpOnVPMajbY67JhE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wrzC2RsT7qypRXN6fpWWFUJjW53BxBZbnIQBk7OqPGVsHLCYb6YlbgzqVLJQD/DYM JkhiaonVK/QPBggaZSbqXpM76V+qOC0jdLIbJpAo+FPQLoR607s6G4xuuPh6MOiuwd wZePXn2ShfgPF+Crxncq+6mvmd5owUwlpVQ+C4PA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Lorenzo Stoakes , Jan Kara , Alexander Viro , Andy Lutomirski , Christian Brauner , Hugh Dickins , "Matthew Wilcox (Oracle)" , Mike Kravetz , Muchun Song , Andrew Morton , "Isaac J. Manjarres" Subject: [PATCH 5.4 380/403] mm: update memfd seal write check to include F_SEAL_WRITE Date: Tue, 26 Aug 2025 13:11:46 +0200 Message-ID: <20250826110917.515769429@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250826110905.607690791@linuxfoundation.org> References: <20250826110905.607690791@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lorenzo Stoakes [ Upstream commit 28464bbb2ddc199433383994bcb9600c8034afa1 ] The seal_check_future_write() function is called by shmem_mmap() or hugetlbfs_file_mmap() to disallow any future writable mappings of an memfd sealed this way. The F_SEAL_WRITE flag is not checked here, as that is handled via the mapping->i_mmap_writable mechanism and so any attempt at a mapping would fail before this could be run. However we intend to change this, meaning this check can be performed for F_SEAL_WRITE mappings also. The logic here is equally applicable to both flags, so update this function to accommodate both and rename it accordingly. Link: https://lkml.kernel.org/r/913628168ce6cce77df7d13a63970bae06a526e0.1697116581.git.lstoakes@gmail.com Signed-off-by: Lorenzo Stoakes Reviewed-by: Jan Kara Cc: Alexander Viro Cc: Andy Lutomirski Cc: Christian Brauner Cc: Hugh Dickins Cc: Matthew Wilcox (Oracle) Cc: Mike Kravetz Cc: Muchun Song Signed-off-by: Andrew Morton Cc: stable@vger.kernel.org Signed-off-by: Isaac J. Manjarres Signed-off-by: Greg Kroah-Hartman --- fs/hugetlbfs/inode.c | 2 +- include/linux/mm.h | 15 ++++++++------- mm/shmem.c | 2 +- 3 files changed, 10 insertions(+), 9 deletions(-) --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -152,7 +152,7 @@ static int hugetlbfs_file_mmap(struct fi vma->vm_flags |= VM_HUGETLB | VM_DONTEXPAND; vma->vm_ops = &hugetlb_vm_ops; - ret = seal_check_future_write(info->seals, vma); + ret = seal_check_write(info->seals, vma); if (ret) return ret; --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2946,25 +2946,26 @@ static inline int pages_identical(struct } /** - * seal_check_future_write - Check for F_SEAL_FUTURE_WRITE flag and handle it + * seal_check_write - Check for F_SEAL_WRITE or F_SEAL_FUTURE_WRITE flags and + * handle them. * @seals: the seals to check * @vma: the vma to operate on * - * Check whether F_SEAL_FUTURE_WRITE is set; if so, do proper check/handling on - * the vma flags. Return 0 if check pass, or <0 for errors. + * Check whether F_SEAL_WRITE or F_SEAL_FUTURE_WRITE are set; if so, do proper + * check/handling on the vma flags. Return 0 if check pass, or <0 for errors. */ -static inline int seal_check_future_write(int seals, struct vm_area_struct *vma) +static inline int seal_check_write(int seals, struct vm_area_struct *vma) { - if (seals & F_SEAL_FUTURE_WRITE) { + if (seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) { /* * New PROT_WRITE and MAP_SHARED mmaps are not allowed when - * "future write" seal active. + * write seals are active. */ if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_WRITE)) return -EPERM; /* - * Since an F_SEAL_FUTURE_WRITE sealed memfd can be mapped as + * Since an F_SEAL_[FUTURE_]WRITE sealed memfd can be mapped as * MAP_SHARED and read-only, take care to not allow mprotect to * revert protections on such mappings. Do this only for shared * mappings. For private mappings, don't need to mask --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2215,7 +2215,7 @@ static int shmem_mmap(struct file *file, struct shmem_inode_info *info = SHMEM_I(file_inode(file)); int ret; - ret = seal_check_future_write(info->seals, vma); + ret = seal_check_write(info->seals, vma); if (ret) return ret;