ima: support for kexec image and initramfs

Add IMA policy support for measuring/appraising the kexec image and
initramfs. Two new IMA policy identifiers KEXEC_KERNEL_CHECK and
KEXEC_INITRAMFS_CHECK are defined.

Example policy rules:
measure func=KEXEC_KERNEL_CHECK
appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig
measure func=KEXEC_INITRAMFS_CHECK
appraise func=KEXEC_INITRAMFS_CHECK appraise_type=imasig

Moving the enumeration to the vfs layer simplified the patches, allowing
the IMA changes, for the most part, to be separated from the other
changes.  Unfortunately, passing either a kernel_read_file_id or a
ima_hooks enumeration within IMA is messy.

Option 1: duplicate kernel_read_file enumeration in ima_hooks

enum kernel_read_file_id {
	...
        READING_KEXEC_IMAGE,
        READING_KEXEC_INITRAMFS,
        READING_MAX_ID

enum ima_hooks {
	...
	KEXEC_KERNEL_CHECK
	KEXEC_INITRAMFS_CHECK

Option 2: define ima_hooks as extension of kernel_read_file
eg: enum ima_hooks {
        FILE_CHECK = READING_MAX_ID,
        MMAP_CHECK,

In order to pass both kernel_read_file_id and ima_hooks values, we
would need to specify a struct containing a union.

struct caller_id {
        union {
                enum ima_hooks func_id;
                enum kernel_read_file_id read_id;
        };
};

Option 3: incorportate the ima_hooks enumeration into kernel_read_file_id,
perhaps changing the enumeration name.

For now, duplicate the new READING_KEXEC_IMAGE/INITRAMFS in the ima_hooks.

Changelog v4:
- replaced switch statement with a kernel_read_file_id to an ima_hooks
id mapping array - Dmitry
- renamed ima_hook tokens KEXEC_CHECK and INITRAMFS_CHECK to
KEXEC_KERNEL_CHECK and KEXEC_INITRAMFS_CHECK respectively - Dave Young

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: Petko Manolov <petkan@mip-labs.com>
Acked-by: Dmitry Kasatkin <dmitry.kasatkin@huawei.com>
Cc: Dave Young <dyoung@redhat.com>

1 files changed, 16 insertions, 1 deletions

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 7571ce8841ff..646134cdf3e8 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -612,6 +612,12 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 				entry->func = MMAP_CHECK;
 			else if (strcmp(args[0].from, "BPRM_CHECK") == 0)
 				entry->func = BPRM_CHECK;
+			else if (strcmp(args[0].from, "KEXEC_KERNEL_CHECK") ==
+				 0)
+				entry->func = KEXEC_KERNEL_CHECK;
+			else if (strcmp(args[0].from, "KEXEC_INITRAMFS_CHECK")
+				 == 0)
+				entry->func = KEXEC_INITRAMFS_CHECK;
 			else
 				result = -EINVAL;
 			if (!result)
@@ -855,7 +861,8 @@ static char *mask_tokens[] = {
 
 enum {
 	func_file = 0, func_mmap, func_bprm,
-	func_module, func_firmware, func_post
+	func_module, func_firmware, func_post,
+	func_kexec_kernel, func_kexec_initramfs
 };
 
 static char *func_tokens[] = {
@@ -864,6 +871,8 @@ static char *func_tokens[] = {
 	"BPRM_CHECK",
 	"MODULE_CHECK",
 	"FIRMWARE_CHECK",
+	"KEXEC_KERNEL_CHECK",
+	"KEXEC_INITRAMFS_CHECK",
 	"POST_SETATTR"
 };
 
@@ -929,6 +938,12 @@ static void policy_func_show(struct seq_file *m, enum ima_hooks func)
 	case POST_SETATTR:
 		seq_printf(m, pt(Opt_func), ft(func_post));
 		break;
+	case KEXEC_KERNEL_CHECK:
+		seq_printf(m, pt(Opt_func), ft(func_kexec_kernel));
+		break;
+	case KEXEC_INITRAMFS_CHECK:
+		seq_printf(m, pt(Opt_func), ft(func_kexec_initramfs));
+		break;
 	default:
 		snprintf(tbuf, sizeof(tbuf), "%d", func);
 		seq_printf(m, pt(Opt_func), tbuf);