Merge tag 'integrity-v6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity

Pull integrity update from Mimi Zohar:
 "A single commit to permit disabling IMA from the boot command line for
  just the kdump kernel.

  The exception itself sort of makes sense. My concern is that
  exceptions do not remain as exceptions, but somehow morph to become
  the norm"

* tag 'integrity-v6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
  ima: add a knob ima= to allow disabling IMA in kdump kernel

Author: torvalds

Documentation/admin-guide/kernel-parameters.txt

@@ -2212,6 +2212,11 @@
 			different crypto accelerators. This option can be used
 			to achieve best performance for particular HW.
 
+	ima=		[IMA] Enable or disable IMA
+			Format: { "off" | "on" }
+			Default: "on"
+			Note that disabling IMA is limited to kdump kernel.
+
 	indirect_target_selection= [X86,Intel] Mitigation control for Indirect
 			Target Selection(ITS) bug in Intel CPUs. Updated
 			microcode is also required for a fix in IBPB.

security/integrity/ima/ima_main.c

@@ -27,6 +27,7 @@
 #include <linux/fs.h>
 #include <linux/iversion.h>
 #include <linux/evm.h>
+#include <linux/crash_dump.h>
 
 #include "ima.h"
 
@@ -38,11 +39,30 @@ int ima_appraise;
 
 int __ro_after_init ima_hash_algo = HASH_ALGO_SHA1;
 static int hash_setup_done;
+static int ima_disabled __ro_after_init;
 
 static struct notifier_block ima_lsm_policy_notifier = {
 	.notifier_call = ima_lsm_policy_change,
 };
 
+static int __init ima_setup(char *str)
+{
+	if (!is_kdump_kernel()) {
+		pr_info("Warning: ima setup option only permitted in kdump");
+		return 1;
+	}
+
+	if (strncmp(str, "off", 3) == 0)
+		ima_disabled = 1;
+	else if (strncmp(str, "on", 2) == 0)
+		ima_disabled = 0;
+	else
+		pr_err("Invalid ima setup option: \"%s\" , please specify ima=on|off.", str);
+
+	return 1;
+}
+__setup("ima=", ima_setup);
+
 static int __init hash_setup(char *str)
 {
 	struct ima_template_desc *template_desc = ima_template_desc_current();
@@ -1186,6 +1206,12 @@ static int __init init_ima(void)
 {
 	int error;
 
+	/*Note that turning IMA off is intentionally limited to kdump kernel.*/
+	if (ima_disabled && is_kdump_kernel()) {
+		pr_info("IMA functionality is disabled");
+		return 0;
+	}
+
 	ima_appraise_parse_cmdline();
 	ima_init_template_list();
 	hash_setup(CONFIG_IMA_DEFAULT_HASH);