diff options
| author | Matthew Garrett <mjg59@srcf.ucam.org> | 2019-08-19 17:17:42 -0700 |
|---|---|---|
| committer | James Morris <jmorris@namei.org> | 2019-08-19 21:54:15 -0700 |
| commit | 7d31f4602f8d366072471ca138e4ea7b8edf9be0 (patch) | |
| tree | d6c84bb75d5972c3c2ba086f6e7179d82f36393d | |
| parent | 9b9d8dda1ed72e9bd560ab0ca93d322a9440510e (diff) | |
| download | linux-7d31f4602f8d366072471ca138e4ea7b8edf9be0.tar.bz2 | |
kexec_load: Disable at runtime if the kernel is locked down
The kexec_load() syscall permits the loading and execution of arbitrary
code in ring 0, which is something that lock-down is meant to prevent. It
makes sense to disable kexec_load() in this situation.
This does not affect kexec_file_load() syscall which can check for a
signature on the image to be booted.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Dave Young <dyoung@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: kexec@lists.infradead.org
Signed-off-by: James Morris <jmorris@namei.org>
| -rw-r--r-- | include/linux/security.h | 1 | ||||
| -rw-r--r-- | kernel/kexec.c | 8 | ||||
| -rw-r--r-- | security/lockdown/lockdown.c | 1 |
3 files changed, 10 insertions, 0 deletions
diff --git a/include/linux/security.h b/include/linux/security.h index e5dd446ef35b..b607a8ac97fe 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -105,6 +105,7 @@ enum lockdown_reason { LOCKDOWN_NONE, LOCKDOWN_MODULE_SIGNATURE, LOCKDOWN_DEV_MEM, + LOCKDOWN_KEXEC, LOCKDOWN_INTEGRITY_MAX, LOCKDOWN_CONFIDENTIALITY_MAX, }; diff --git a/kernel/kexec.c b/kernel/kexec.c index 1b018f1a6e0d..bc933c0db9bf 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -206,6 +206,14 @@ static inline int kexec_load_check(unsigned long nr_segments, return result; /* + * kexec can be used to circumvent module loading restrictions, so + * prevent loading in that case + */ + result = security_locked_down(LOCKDOWN_KEXEC); + if (result) + return result; + + /* * Verify we have a legal set of flags * This leaves us room for future extensions. */ diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c index 240ecaa10a1d..aaf30ad351f9 100644 --- a/security/lockdown/lockdown.c +++ b/security/lockdown/lockdown.c @@ -20,6 +20,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = { [LOCKDOWN_NONE] = "none", [LOCKDOWN_MODULE_SIGNATURE] = "unsigned module loading", [LOCKDOWN_DEV_MEM] = "/dev/mem,kmem,port", + [LOCKDOWN_KEXEC] = "kexec of unsigned images", [LOCKDOWN_INTEGRITY_MAX] = "integrity", [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", }; |