6a9b88204c
VFS pathnames are stored in the names_cache slab cache, either inline
or across an entire allocation entry (when approaching PATH_MAX). These
are copied to/from userspace, so they must be entirely whitelisted.
cache object allocation:
include/linux/fs.h:
#define __getname() kmem_cache_alloc(names_cachep, GFP_KERNEL)
example usage trace:
strncpy_from_user+0x4d/0x170
getname_flags+0x6f/0x1f0
user_path_at_empty+0x23/0x40
do_mount+0x69/0xda0
SyS_mount+0x83/0xd0
fs/namei.c:
getname_flags(...):
...
result = __getname();
...
kname = (char *)result->iname;
result->name = kname;
len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX);
...
if (unlikely(len == EMBEDDED_NAME_MAX)) {
const size_t size = offsetof(struct filename, iname[1]);
kname = (char *)result;
result = kzalloc(size, GFP_KERNEL);
...
result->name = kname;
len = strncpy_from_user(kname, filename, PATH_MAX);
In support of usercopy hardening, this patch defines the entire cache
object in the names_cache slab cache as whitelisted, since it may entirely
hold name strings to be copied to/from userspace.
This patch is verbatim 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, add usage trace]
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
|
||
|---|---|---|
| Documentation | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
README
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.