kernel_optimize_test/security
Eric Snowberg ab5050fd74 lockdown: Fix kexec lockdown bypass with ima policy
commit 543ce63b664e2c2f9533d089a4664b559c3e6b5b upstream.

The lockdown LSM is primarily used in conjunction with UEFI Secure Boot.
This LSM may also be used on machines without UEFI.  It can also be
enabled when UEFI Secure Boot is disabled.  One of lockdown's features
is to prevent kexec from loading untrusted kernels.  Lockdown can be
enabled through a bootparam or after the kernel has booted through
securityfs.

If IMA appraisal is used with the "ima_appraise=log" boot param,
lockdown can be defeated with kexec on any machine when Secure Boot is
disabled or unavailable.  IMA prevents setting "ima_appraise=log" from
the boot param when Secure Boot is enabled, but this does not cover
cases where lockdown is used without Secure Boot.

To defeat lockdown, boot without Secure Boot and add ima_appraise=log to
the kernel command line; then:

  $ echo "integrity" > /sys/kernel/security/lockdown
  $ echo "appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig" > \
    /sys/kernel/security/ima/policy
  $ kexec -ls unsigned-kernel

Add a call to verify ima appraisal is set to "enforce" whenever lockdown
is enabled.  This fixes CVE-2022-21505.

Cc: stable@vger.kernel.org
Fixes: 29d3c1c8df ("kexec: Allow kexec_file() with appropriate IMA policy when locked down")
Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
Acked-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: John Haxby <john.haxby@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-29 17:19:06 +02:00
..
apparmor apparmor: fix error check 2021-11-18 14:04:22 +01:00
bpf bpf: Implement bpf_local_storage for inodes 2020-08-25 15:00:04 -07:00
integrity lockdown: Fix kexec lockdown bypass with ima policy 2022-07-29 17:19:06 +02:00
keys KEYS: fix length validation in keyctl_pkey_params_get_2() 2022-04-08 14:39:50 +02:00
loadpin LSM: Add "contents" flag to kernel_read_file hook 2020-10-05 13:37:03 +02:00
lockdown Merge branch 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2020-06-02 17:36:24 -07:00
safesetid LSM: SafeSetID: Fix warnings reported by test bot 2020-10-13 09:17:36 -07:00
selinux lsm,selinux: pass flowi_common instead of flowi to the LSM hooks 2022-06-09 10:21:09 +02:00
smack Fix incorrect type in assignment of ipv6 port for audit 2022-04-08 14:40:31 +02:00
tomoyo TOMOYO: fix __setup handlers return values 2022-04-08 14:40:18 +02:00
yama task_work: cleanup notification modes 2020-10-17 15:05:30 -06:00
commoncap.c security: commoncap: fix -Wstringop-overread warning 2021-05-11 14:47:36 +02:00
device_cgroup.c device_cgroup: Fix RCU list debugging warning 2020-08-20 11:25:03 -07:00
inode.c
Kconfig x86/retbleed: Add fine grained Kconfig knobs 2022-07-25 11:26:50 +02:00
Kconfig.hardening security: allow using Clang's zero initialization for stack variables 2020-06-16 02:06:23 -07:00
lsm_audit.c dump_common_audit_data(): fix racy accesses to ->d_name 2021-01-19 18:27:29 +01:00
Makefile device_cgroup: Cleanup cgroup eBPF device filter code 2020-04-13 14:41:54 -04:00
min_addr.c sysctl: pass kernel pointers to ->proc_handler 2020-04-27 02:07:40 -04:00
security.c lsm,selinux: pass flowi_common instead of flowi to the LSM hooks 2022-06-09 10:21:09 +02:00