linux/fs/befs
David Windsor 0fc256d3ad 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>
2018-01-15 12:07:54 -08:00
..
ChangeLog Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
Kconfig fs/befs: remove depends on CONFIG_EXPERIMENTAL 2013-01-21 14:39:04 -08:00
Makefile BEFS: logging cleanup 2014-04-03 16:21:25 -07:00
TODO Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
befs.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
befs_fs_types.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
btree.c befs: add kernel-doc formatting for befs_bt_read_super() 2017-07-09 10:42:50 +01:00
btree.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
datastream.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
datastream.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
debug.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
endian.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
inode.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
inode.h befs: remove trailing whitespaces 2016-12-22 11:25:23 +00:00
io.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
io.h befs: remove trailing whitespaces 2016-12-22 11:25:23 +00:00
linuxvfs.c befs: Define usercopy region in befs_inode_cache slab cache 2018-01-15 12:07:54 -08:00
super.c befs: fix style issues in super.c 2016-10-08 10:01:34 +01:00
super.h befs: fix style issues in header files 2016-12-22 11:25:22 +00:00