From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f71.google.com (mail-pg0-f71.google.com [74.125.83.71]) by kanga.kvack.org (Postfix) with ESMTP id 95C556B028C for ; Wed, 20 Sep 2017 16:46:08 -0400 (EDT) Received: by mail-pg0-f71.google.com with SMTP id p5so7351203pgn.7 for ; Wed, 20 Sep 2017 13:46:08 -0700 (PDT) Received: from mail-sor-f41.google.com (mail-sor-f41.google.com. [209.85.220.41]) by mx.google.com with SMTPS id t6sor2068318pgt.170.2017.09.20.13.46.07 for (Google Transport Security); Wed, 20 Sep 2017 13:46:07 -0700 (PDT) From: Kees Cook Subject: [PATCH v3 09/31] jfs: Define usercopy region in jfs_ip slab cache Date: Wed, 20 Sep 2017 13:45:15 -0700 Message-Id: <1505940337-79069-10-git-send-email-keescook@chromium.org> In-Reply-To: <1505940337-79069-1-git-send-email-keescook@chromium.org> References: <1505940337-79069-1-git-send-email-keescook@chromium.org> Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org Cc: Kees Cook , David Windsor , Dave Kleikamp , jfs-discussion@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, netdev@vger.kernel.org, linux-mm@kvack.org, kernel-hardening@lists.openwall.com From: David Windsor The jfs symlink pathnames, stored in struct jfs_inode_info.i_inline and therefore contained in the jfs_ip slab cache, need to be copied to/from userspace. cache object allocation: fs/jfs/super.c: jfs_alloc_inode(...): ... jfs_inode = kmem_cache_alloc(jfs_inode_cachep, GFP_NOFS); ... return &jfs_inode->vfs_inode; fs/jfs/jfs_incore.h: JFS_IP(struct inode *inode): return container_of(inode, struct jfs_inode_info, vfs_inode); fs/jfs/inode.c: jfs_iget(...): ... inode->i_link = JFS_IP(inode)->i_inline; example usage trace: readlink_copy+0x43/0x70 vfs_readlink+0x62/0x110 SyS_readlinkat+0x100/0x130 fs/namei.c: readlink_copy(..., link): ... copy_to_user(..., link, len); (inlined in vfs_readlink) generic_readlink(dentry, ...): struct inode *inode = d_inode(dentry); const char *link = inode->i_link; ... readlink_copy(..., link); In support of usercopy hardening, this patch defines a region in the jfs_ip slab cache in which userspace copy operations are allowed. This region is known as the slab cache's usercopy region. Slab caches can now check that each copy operation involving cache-managed memory falls entirely within the slab's usercopy region. This patch is modified from Brad Spengler/PaX Team's PAX_USERCOPY whitelisting code in the last public patch of grsecurity/PaX based on my understanding of the code. Changes or omissions from the original code are mine and don't reflect the original grsecurity/PaX code. Signed-off-by: David Windsor [kees: adjust commit log, provide usage trace] Cc: Dave Kleikamp Cc: jfs-discussion@lists.sourceforge.net Signed-off-by: Kees Cook --- fs/jfs/super.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/fs/jfs/super.c b/fs/jfs/super.c index 2f14677169c3..e018412608d4 100644 --- a/fs/jfs/super.c +++ b/fs/jfs/super.c @@ -966,9 +966,11 @@ static int __init init_jfs_fs(void) int rc; jfs_inode_cachep = - kmem_cache_create("jfs_ip", sizeof(struct jfs_inode_info), 0, - SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD|SLAB_ACCOUNT, - init_once); + kmem_cache_create_usercopy("jfs_ip", sizeof(struct jfs_inode_info), + 0, SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD|SLAB_ACCOUNT, + offsetof(struct jfs_inode_info, i_inline), + sizeof_field(struct jfs_inode_info, i_inline), + init_once); if (jfs_inode_cachep == NULL) return -ENOMEM; -- 2.7.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org