| Message ID | 1515531365-37423-14-git-send-email-keescook@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 01/09/2018 08:55 PM, Kees Cook wrote: > From: David Windsor <dave@nullcore.net> > > befs symlink pathnames, stored in struct befs_inode_info.i_data.symlink > and therefore contained in the befs_inode_cache slab cache, need to be > copied to/from userspace. > > cache object allocation: > fs/befs/linuxvfs.c: > befs_alloc_inode(...): > ... > bi = kmem_cache_alloc(befs_inode_cachep, GFP_KERNEL); > ... > return &bi->vfs_inode; > > befs_iget(...): > ... > strlcpy(befs_ino->i_data.symlink, raw_inode->data.symlink, > BEFS_SYMLINK_LEN); > ... > inode->i_link = befs_ino->i_data.symlink; > > 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 > befs_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 dynamically sized 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: Luis de Bethencourt <luisbg@kernel.org> > Cc: Salah Triki <salah.triki@gmail.com> > Signed-off-by: Kees Cook <keescook@chromium.org> > Acked-by: Luis de Bethencourt <luisbg@kernel.org> > --- > fs/befs/linuxvfs.c | 14 +++++++++----- > 1 file changed, 9 insertions(+), 5 deletions(-) > > diff --git a/fs/befs/linuxvfs.c b/fs/befs/linuxvfs.c > index ee236231cafa..af2832aaeec5 100644 > --- a/fs/befs/linuxvfs.c > +++ b/fs/befs/linuxvfs.c > @@ -444,11 +444,15 @@ static struct inode *befs_iget(struct super_block *sb, unsigned long ino) > static int __init > befs_init_inodecache(void) > { > - befs_inode_cachep = kmem_cache_create("befs_inode_cache", > - sizeof (struct befs_inode_info), > - 0, (SLAB_RECLAIM_ACCOUNT| > - SLAB_MEM_SPREAD|SLAB_ACCOUNT), > - init_once); > + befs_inode_cachep = kmem_cache_create_usercopy("befs_inode_cache", > + sizeof(struct befs_inode_info), 0, > + (SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD| > + SLAB_ACCOUNT), > + offsetof(struct befs_inode_info, > + i_data.symlink), > + sizeof_field(struct befs_inode_info, > + i_data.symlink), > + init_once); > if (befs_inode_cachep == NULL) > return -ENOMEM; > > Hi Kees, I've tested this and it works well. You can have me as: Signed-off-by, Tested-by, or the current Acked-by. Whatever you think is better. Thanks for the great work. Your rock! Luis
diff --git a/fs/befs/linuxvfs.c b/fs/befs/linuxvfs.c index ee236231cafa..af2832aaeec5 100644 --- a/fs/befs/linuxvfs.c +++ b/fs/befs/linuxvfs.c @@ -444,11 +444,15 @@ static struct inode *befs_iget(struct super_block *sb, unsigned long ino) static int __init befs_init_inodecache(void) { - befs_inode_cachep = kmem_cache_create("befs_inode_cache", - sizeof (struct befs_inode_info), - 0, (SLAB_RECLAIM_ACCOUNT| - SLAB_MEM_SPREAD|SLAB_ACCOUNT), - init_once); + befs_inode_cachep = kmem_cache_create_usercopy("befs_inode_cache", + sizeof(struct befs_inode_info), 0, + (SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD| + SLAB_ACCOUNT), + offsetof(struct befs_inode_info, + i_data.symlink), + sizeof_field(struct befs_inode_info, + i_data.symlink), + init_once); if (befs_inode_cachep == NULL) return -ENOMEM;