ima: force signature verification when CONFIG_KEXEC_SIG is configured

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: 99d5cad ("kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE") Reported-and-suggested-by: Mimi Zohar <[email protected]> Signed-off-by: Coiby Xu <[email protected]> Signed-off-by: Mimi Zohar <[email protected]>
niw · Jul 13, 2022 · af16df5 · af16df5
1 parent d2ee2cf
commit af16df5
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Showing 3 changed files with 18 additions and 1 deletion.
diff --git 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
@@ -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
@@ -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;