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authorDavid Windsor <dave@nullcore.net>2017-06-10 22:50:32 -0400
committerKees Cook <keescook@chromium.org>2018-01-15 12:07:54 -0800
commit0fc256d3ad76f2552de0db781854506bb623715a (patch)
treef5ee18f470f977641fe3853c9ad011584dcf3068 /fs
parent8d2704d382a9fd14f65dcdd2a3459067162fd4e6 (diff)
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befs: Define usercopy region in befs_inode_cache slab cache
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>
Diffstat (limited to 'fs')
-rw-r--r--fs/befs/linuxvfs.c14
1 files 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 @@ unacquire_none:
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;