ima: force signature verification when CONFIG_KEXEC_SIG is configured

stable inclusion
from stable-v5.10.132
commit eb360267e1e972475023d06546e18365a222698c
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5YS3T

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=eb360267e1e972475023d06546e18365a222698c

--------------------------------

[ Upstream commit af16df54 ]

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: 99d5cadf ("kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE")
Reported-and-suggested-by: NMimi Zohar <zohar@linux.ibm.com>
Signed-off-by: NCoiby Xu <coxu@redhat.com>
Signed-off-by: NMimi Zohar <zohar@linux.ibm.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>

arch/x86/kernel/ima_arch.c

@@ -88,6 +88,8 @@ 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;

include/linux/kexec.h

@@ -434,6 +434,12 @@ 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 */

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);
 
 /*
@@ -193,7 +202,7 @@ 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;
 		}