linux/security
Mathieu Desnoyers 8aec0f5d41 Fix: compat_rw_copy_check_uvector() misuse in aio, readv, writev, and security keys
Looking at mm/process_vm_access.c:process_vm_rw() and comparing it to
compat_process_vm_rw() shows that the compatibility code requires an
explicit "access_ok()" check before calling
compat_rw_copy_check_uvector(). The same difference seems to appear when
we compare fs/read_write.c:do_readv_writev() to
fs/compat.c:compat_do_readv_writev().

This subtle difference between the compat and non-compat requirements
should probably be debated, as it seems to be error-prone. In fact,
there are two others sites that use this function in the Linux kernel,
and they both seem to get it wrong:

Now shifting our attention to fs/aio.c, we see that aio_setup_iocb()
also ends up calling compat_rw_copy_check_uvector() through
aio_setup_vectored_rw(). Unfortunately, the access_ok() check appears to
be missing. Same situation for
security/keys/compat.c:compat_keyctl_instantiate_key_iov().

I propose that we add the access_ok() check directly into
compat_rw_copy_check_uvector(), so callers don't have to worry about it,
and it therefore makes the compat call code similar to its non-compat
counterpart. Place the access_ok() check in the same location where
copy_from_user() can trigger a -EFAULT error in the non-compat code, so
the ABI behaviors are alike on both compat and non-compat.

While we are here, fix compat_do_readv_writev() so it checks for
compat_rw_copy_check_uvector() negative return values.

And also, fix a memory leak in compat_keyctl_instantiate_key_iov() error
handling.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-03-12 11:05:45 -07:00
..
apparmor new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
integrity hlist: drop the node parameter from iterators 2013-02-27 19:10:24 -08:00
keys Fix: compat_rw_copy_check_uvector() misuse in aio, readv, writev, and security keys 2013-03-12 11:05:45 -07:00
selinux Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-03-03 13:23:03 -08:00
smack new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
tomoyo new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
yama Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2012-12-17 15:44:47 -08:00
capability.c tun: fix LSM/SELinux labeling of tun/tap devices 2013-01-14 18:16:59 -05:00
commoncap.c kill f_vfsmnt 2013-02-26 02:46:10 -05:00
device_cgroup.c device_cgroup: don't grab mutex in rcu callback 2013-02-21 17:22:15 -08:00
inode.c
Kconfig
lsm_audit.c
Makefile
min_addr.c
security.c tun: fix LSM/SELinux labeling of tun/tap devices 2013-01-14 18:16:59 -05:00