Patch "ima: force signature verification when CONFIG_KEXEC_SIG is configured" has been added to the 5.18-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    ima: force signature verification when CONFIG_KEXEC_SIG is configured

to the 5.18-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ima-force-signature-verification-when-config_kexec_s.patch
and it can be found in the queue-5.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 88c69fd7a6542d6df8d34b7252ff15ac3721f869
Author: Coiby Xu <coxu@xxxxxxxxxx>
Date:   Wed Jul 13 15:21:11 2022 +0800

    ima: force signature verification when CONFIG_KEXEC_SIG is configured
    
    [ 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@xxxxxxxxxxxxx>
    Signed-off-by: Coiby Xu <coxu@xxxxxxxxxx>
    Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index fcd5035209f1..8d573baaab29 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 c108a2a88754..bb0fb63f563c 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;