| Message ID | 1503956111-36652-9-git-send-email-keescook@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon 28-08-17 14:34:49, Kees Cook wrote: > From: David Windsor <dave@nullcore.net> > > The ext2 symlink pathnames, stored in struct ext2_inode_info.i_data and > therefore contained in the ext2_inode_cache slab cache, need to be copied > to/from userspace. > > cache object allocation: > fs/ext2/super.c: > ext2_alloc_inode(...): > struct ext2_inode_info *ei; > ... > ei = kmem_cache_alloc(ext2_inode_cachep, GFP_NOFS); > ... > return &ei->vfs_inode; > > fs/ext2/ext2.h: > EXT2_I(struct inode *inode): > return container_of(inode, struct ext2_inode_info, vfs_inode); > > fs/ext2/namei.c: > ext2_symlink(...): > ... > inode->i_link = (char *)&EXT2_I(inode)->i_data; > > 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 into 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 > ext2_inode_cache 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 <dave@nullcore.net> > [kees: adjust commit log, provide usage trace] > Cc: Jan Kara <jack@suse.com> > Cc: linux-ext4@vger.kernel.org > Signed-off-by: Kees Cook <keescook@chromium.org> Looks good. You can add: Acked-by: Jan Kara <jack@suse.cz> Honza > --- > fs/ext2/super.c | 12 +++++++----- > 1 file changed, 7 insertions(+), 5 deletions(-) > > diff --git a/fs/ext2/super.c b/fs/ext2/super.c > index 7b1bc9059863..670142cde59d 100644 > --- a/fs/ext2/super.c > +++ b/fs/ext2/super.c > @@ -219,11 +219,13 @@ static void init_once(void *foo) > > static int __init init_inodecache(void) > { > - ext2_inode_cachep = kmem_cache_create("ext2_inode_cache", > - sizeof(struct ext2_inode_info), > - 0, (SLAB_RECLAIM_ACCOUNT| > - SLAB_MEM_SPREAD|SLAB_ACCOUNT), > - init_once); > + ext2_inode_cachep = kmem_cache_create_usercopy("ext2_inode_cache", > + sizeof(struct ext2_inode_info), 0, > + (SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD| > + SLAB_ACCOUNT), > + offsetof(struct ext2_inode_info, i_data), > + sizeof_field(struct ext2_inode_info, i_data), > + init_once); > if (ext2_inode_cachep == NULL) > return -ENOMEM; > return 0; > -- > 2.7.4 > >
diff --git a/fs/ext2/super.c b/fs/ext2/super.c index 7b1bc9059863..670142cde59d 100644 --- a/fs/ext2/super.c +++ b/fs/ext2/super.c @@ -219,11 +219,13 @@ static void init_once(void *foo) static int __init init_inodecache(void) { - ext2_inode_cachep = kmem_cache_create("ext2_inode_cache", - sizeof(struct ext2_inode_info), - 0, (SLAB_RECLAIM_ACCOUNT| - SLAB_MEM_SPREAD|SLAB_ACCOUNT), - init_once); + ext2_inode_cachep = kmem_cache_create_usercopy("ext2_inode_cache", + sizeof(struct ext2_inode_info), 0, + (SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD| + SLAB_ACCOUNT), + offsetof(struct ext2_inode_info, i_data), + sizeof_field(struct ext2_inode_info, i_data), + init_once); if (ext2_inode_cachep == NULL) return -ENOMEM; return 0;