leandrof/linux
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
4f0496d8ff
linux/security
History
Mimi Zohar 4f0496d8ff ima: based on policy warn about loading firmware (pre-allocated buffer) 
Some systems are memory constrained but they need to load very large
firmwares.  The firmware subsystem allows drivers to request this
firmware be loaded from the filesystem, but this requires that the
entire firmware be loaded into kernel memory first before it's provided
to the driver.  This can lead to a situation where we map the firmware
twice, once to load the firmware into kernel memory and once to copy the
firmware into the final resting place.

To resolve this problem, commit a098ecd2fa ("firmware: support loading
into a pre-allocated buffer") introduced request_firmware_into_buf() API
that allows drivers to request firmware be loaded directly into a
pre-allocated buffer.

Do devices using pre-allocated memory run the risk of the firmware being
accessible to the device prior to the completion of IMA's signature
verification any more than when using two buffers? (Refer to mailing list
discussion[1]).

Only on systems with an IOMMU can the access be prevented.  As long as
the signature verification completes prior to the DMA map is performed,
the device can not access the buffer.  This implies that the same buffer
can not be re-used.  Can we ensure the buffer has not been DMA mapped
before using the pre-allocated buffer?

[1] https://lkml.org/lkml/2018/7/10/56

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Morris <james.morris@microsoft.com>
2018-07-16 12:31:57 -07:00
..
apparmor + Features 2018-06-14 16:11:28 +09:00
integrity ima: based on policy warn about loading firmware (pre-allocated buffer) 2018-07-16 12:31:57 -07:00
keys treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
loadpin module: replace the existing LSM hook in init_module 2018-07-16 12:31:57 -07:00
selinux module: replace the existing LSM hook in init_module 2018-07-16 12:31:57 -07:00
smack Merge branch 'smack-for-4.18' of https://github.com/cschaufler/next-smack into next-smack 2018-06-05 13:18:58 -07:00
tomoyo net: make getname() functions return length rather than use int* parameter 2018-02-12 14:15:04 -05:00
yama pids: introduce find_get_task_by_vpid() helper 2018-02-06 18:32:46 -08:00
commoncap.c capabilities: Allow privileged user in s_user_ns to set security.* xattrs 2018-05-24 12:03:31 -05:00
device_cgroup.c docs: fix broken references with multiple hints 2018-06-15 18:10:01 -03:00
inode.c securityfs: add the ability to support symlinks 2017-06-08 12:51:43 -07:00
Kconfig Currently, hardened usercopy performs dynamic bounds checking on slab 2018-02-03 16:25:42 -08:00
lsm_audit.c audit: use inline function to get audit context 2018-05-14 17:24:18 -04:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
min_addr.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
security.c ima: based on policy require signed kexec kernel images 2018-07-16 12:31:57 -07:00