[PATCH 5.15 095/167] ima: force signature verification when CONFIG_KEXEC_SIG is configured

Greg Kroah-Hartman
2022-07-19T12:41:20Z

From: Coiby Xu <coxu@redhat.com>

[ Upstream commit af16df54b89dee72df253abc5e7b5e8a6d16c11c ]

Currently, an unsigned kernel could be kexec'ed when IMA arch specific
policy is configured unless lockdown is enabled. Enforce kernel
signature verification check in the kexec_file_load syscall when IMA
arch specific policy is configured.

Fixes: 99d5cadfde2b ("kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE")
Reported-and-suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Coiby Xu <coxu@redhat.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/kexec.h | 6 ++++++
kernel/kexec_file.c | 11 ++++++++++-
security/integrity/ima/ima_efi.c | 2 ++
3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 33be67c2f7ff..cf042d41c87b 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -452,6 +452,12 @@ static inline int kexec_crash_loaded(void) { return 0; }
#define kexec_in_progress false
#endif /* CONFIG_KEXEC_CORE */

+#ifdef CONFIG_KEXEC_SIG
+void set_kexec_sig_enforced(void);
+#else
+static inline void set_kexec_sig_enforced(void) {}
+#endif
+
#endif /* !defined(__ASSEBMLY__) */

#endif /* LINUX_KEXEC_H */
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index e289e60ba3ad..f7a4fd4d243f 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -29,6 +29,15 @@
#include <linux/vmalloc.h>
#include "kexec_internal.h"

+#ifdef CONFIG_KEXEC_SIG
+static bool sig_enforce = IS_ENABLED(CONFIG_KEXEC_SIG_FORCE);
+
+void set_kexec_sig_enforced(void)
+{
+ sig_enforce = true;
+}
+#endif
+
static int kexec_calculate_store_digests(struct kimage *image);

/*
@@ -159,7 +168,7 @@ kimage_validate_signature(struct kimage *image)
image->kernel_buf_len);
if (ret) {

- if (IS_ENABLED(CONFIG_KEXEC_SIG_FORCE)) {
+ if (sig_enforce) {
pr_notice("Enforced kernel signature verification failed (%d).\n", ret);
return ret;
}
diff --git a/security/integrity/ima/ima_efi.c b/security/integrity/ima/ima_efi.c
index 71786d01946f..9db66fe310d4 100644
--- a/security/integrity/ima/ima_efi.c
+++ b/security/integrity/ima/ima_efi.c
@@ -67,6 +67,8 @@ const char * const *arch_get_ima_policy(void)
if (IS_ENABLED(CONFIG_IMA_ARCH_POLICY) && arch_ima_get_secureboot()) {
if (IS_ENABLED(CONFIG_MODULE_SIG))
set_module_sig_enforced();
+ if (IS_ENABLED(CONFIG_KEXEC_SIG))
+ set_kexec_sig_enforced();
return sb_arch_rules;
}
return NULL;
--
2.35.1