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Groups > linux.kernel > #1736134
| From | Kees Cook <keescook@chromium.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH v3 08/31] ext2: Define usercopy region in ext2_inode_cache slab cache |
| Date | 2017-09-20 23:00 +0200 |
| Message-ID | <urUgb-855-61@gated-at.bofh.it> (permalink) |
| References | <urU6t-818-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
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>
Acked-by: Jan Kara <jack@suse.cz>
---
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 1458706bd2ec..789c29987b36 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -220,11 +220,13 @@ 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
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[PATCH v3 00/31] Hardened usercopy whitelisting Kees Cook <keescook@chromium.org> - 2017-09-20 22:50 +0200
[PATCH v3 26/31] fork: Provide usercopy whitelisting for task_struct Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
[PATCH v3 15/31] xfs: Define usercopy region in xfs_inode slab cache Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
[PATCH v3 07/31] ext4: Define usercopy region in ext4_inode_cache slab cache Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
[PATCH v3 29/31] arm: Implement thread_struct whitelist for hardened usercopy Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
[PATCH v3 25/31] fork: Define usercopy region in thread_stack slab caches Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
[PATCH v3 02/31] usercopy: Enforce slab cache usercopy region boundaries Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
Re: [PATCH v3 02/31] usercopy: Enforce slab cache usercopy region boundaries Christopher Lameter <cl@linux.com> - 2017-09-21 17:30 +0200
[PATCH v3 23/31] net: Restrict unwhitelisted proto caches to size 0 Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
[PATCH v3 17/31] scsi: Define usercopy region in scsi_sense_cache slab cache Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
[PATCH v3 19/31] ip: Define usercopy region in IP proto slab cache Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
[PATCH v3 28/31] arm64: Implement thread_struct whitelist for hardened usercopy Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
[PATCH v3 21/31] sctp: Define usercopy region in SCTP proto slab cache Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
[PATCH v3 31/31] lkdtm: Update usercopy tests for whitelisting Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
[PATCH v3 01/31] usercopy: Prepare for usercopy whitelisting Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
Re: [PATCH v3 01/31] usercopy: Prepare for usercopy whitelisting Christopher Lameter <cl@linux.com> - 2017-09-21 17:30 +0200
[PATCH v3 08/31] ext2: Define usercopy region in ext2_inode_cache slab cache Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
[PATCH v3 18/31] net: Define usercopy region in struct proto slab cache Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
[PATCH v3 24/31] fork: Define usercopy region in mm_struct slab caches Kees Cook <keescook@chromium.org> - 2017-09-20 23:00 +0200
[PATCH v3 04/31] dcache: Define usercopy region in dentry_cache slab cache Kees Cook <keescook@chromium.org> - 2017-09-20 23:10 +0200
[PATCH v3 27/31] x86: Implement thread_struct whitelist for hardened usercopy Kees Cook <keescook@chromium.org> - 2017-09-20 23:10 +0200
[PATCH v3 03/31] usercopy: Mark kmalloc caches as usercopy caches Kees Cook <keescook@chromium.org> - 2017-09-20 23:10 +0200
Re: [PATCH v3 03/31] usercopy: Mark kmalloc caches as usercopy caches Christopher Lameter <cl@linux.com> - 2017-09-21 17:30 +0200
Re: [kernel-hardening] Re: [PATCH v3 03/31] usercopy: Mark kmalloc caches as usercopy caches Kees Cook <keescook@chromium.org> - 2017-09-21 17:50 +0200
Re: [kernel-hardening] Re: [PATCH v3 03/31] usercopy: Mark kmalloc caches as usercopy caches Christopher Lameter <cl@linux.com> - 2017-09-21 18:10 +0200
Re: [kernel-hardening] Re: [PATCH v3 03/31] usercopy: Mark kmalloc caches as usercopy caches Kees Cook <keescook@chromium.org> - 2017-09-21 20:30 +0200
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