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: 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>

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index ce6536f1d269970856ecabad52f7a7604f27e210..475683cd67f1620f27aa2d32acb892358e64e047 100644 (file)
--- 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 145321a5e798a647f299b1728a61231d166621ce..f9261c07b048747c6d594c1c29327628bbb15cac 100644 (file)
--- 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 71786d01946f4539d6be8933bed6d3829f479961..9db66fe310d424f44c882a6e5702dddbef592f84 100644 (file)
--- 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;