kernel_optimize_test/security/integrity
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
..
evm Revert "evm: Fix memleak in init_desc" 2022-07-21 21:20:02 +02:00
ima lockdown: Fix kexec lockdown bypass with ima policy 2022-07-29 17:19:06 +02:00
platform_certs efi: Do not import certificates from UEFI Secure Boot for T2 Macs 2022-06-09 10:21:22 +02:00
digsig_asymmetric.c integrity-v5.10 2020-10-15 15:58:18 -07:00
digsig.c fs/kernel_file_read: Add "offset" arg for partial reads 2020-10-05 13:37:04 +02:00
iint.c integrity: double check iint_cache was initialized 2021-03-30 14:31:55 +02:00
integrity_audit.c integrity: check the return value of audit_log_start() 2022-02-16 12:54:16 +01:00
integrity.h integrity: Add errno field in audit message 2020-07-16 21:48:11 -04:00
Kconfig
Makefile