linux-kernel - [PATCH 2/3] kexec: measure boot command line

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Message-Id: <1466602505-21915-3-git-send-email-zohar@linux.vnet.ibm.com>
Date:	Wed, 22 Jun 2016 09:35:04 -0400
From:	Mimi Zohar <zohar@...ux.vnet.ibm.com>
To:	linux-security-module <linux-security-module@...r.kernel.org>,
	linux-ima-devel <linux-ima-devel@...ts.sourceforge.net>
Cc:	Dave Young <dyoung@...hat.com>, kexec@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Eric Biederman <ebiederm@...ssion.com>,
	Mimi Zohar <zohar@...ux.vnet.ibm.com>
Subject: [PATCH 2/3] kexec: measure boot command line

This patch defines the buffer identifier "KEXEC_CMDLINE_CHECK" for
measuring the boot command line.

eg: echo -n -e `cat /proc/cmdline | sed 's/^.*root=/root=/'` | sha256sum

Signed-off-by: Mimi Zohar <zohar@...ux.vnet.ibm.com>
---
 Documentation/ABI/testing/ima_policy | 1 +
 include/linux/ima.h                  | 1 +
 kernel/kexec_file.c                  | 4 ++++
 security/integrity/ima/ima.h         | 1 +
 security/integrity/ima/ima_buffer.c  | 2 ++
 security/integrity/ima/ima_policy.c  | 9 ++++++++-
 6 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy
index bb0f9a1..5a99c6f 100644
--- a/Documentation/ABI/testing/ima_policy
+++ b/Documentation/ABI/testing/ima_policy
@@ -28,6 +28,7 @@ Description:
 		base: 	func:= [BPRM_CHECK][MMAP_CHECK][FILE_CHECK][MODULE_CHECK]
 				[FIRMWARE_CHECK]
 				[KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK]
+				[KEXEC_CMDLINE_CHECK]
 			mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND]
 			       [[^]MAY_EXEC]
 			fsmagic:= hex value
diff --git a/include/linux/ima.h b/include/linux/ima.h
index 01319b3..88203f9 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -14,6 +14,7 @@
 struct linux_binprm;
 
 enum ima_buffer_id {
+	MEASURING_KEXEC_CMDLINE,
 	MEASURING_MAX_BUFFER_ID
 };
 
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 503bc2d..acc8dad1 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -19,6 +19,7 @@
 #include <linux/mutex.h>
 #include <linux/list.h>
 #include <linux/fs.h>
+#include <linux/ima.h>
 #include <crypto/hash.h>
 #include <crypto/sha.h>
 #include <linux/syscalls.h>
@@ -178,6 +179,9 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
 			ret = -EINVAL;
 			goto out;
 		}
+
+		ima_buffer_check(image->cmdline_buf, cmdline_len - 1,
+				 MEASURING_KEXEC_CMDLINE);
 	}
 
 	/* Call arch image load handlers */
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index cc2e77b..5f21a9a 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -150,6 +150,7 @@ enum ima_hooks {
 	FIRMWARE_CHECK,
 	KEXEC_KERNEL_CHECK,
 	KEXEC_INITRAMFS_CHECK,
+	KEXEC_CMDLINE_CHECK,
 	POLICY_CHECK,
 	MAX_CHECK
 };
diff --git a/security/integrity/ima/ima_buffer.c b/security/integrity/ima/ima_buffer.c
index 84c9494..e74131b 100644
--- a/security/integrity/ima/ima_buffer.c
+++ b/security/integrity/ima/ima_buffer.c
@@ -20,6 +20,8 @@ struct buffer_idmap {
 };
 
 static struct buffer_idmap _idmap[MEASURING_MAX_BUFFER_ID] = {
+	[MEASURING_KEXEC_CMDLINE].func = KEXEC_CMDLINE_CHECK,
+	[MEASURING_KEXEC_CMDLINE].buf = "boot-cmdline",
 };
 
 static void process_buffer_measurement(void *buf, loff_t size,
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 521d612..8e53f84 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -663,6 +663,9 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 			else if (strcmp(args[0].from, "KEXEC_INITRAMFS_CHECK")
 				 == 0)
 				entry->func = KEXEC_INITRAMFS_CHECK;
+			else if (strcmp(args[0].from, "KEXEC_CMDLINE_CHECK")
+				 == 0)
+				entry->func = KEXEC_CMDLINE_CHECK;
 			else if (strcmp(args[0].from, "POLICY_CHECK") == 0)
 				entry->func = POLICY_CHECK;
 			else
@@ -926,7 +929,7 @@ enum {
 	func_file = 0, func_mmap, func_bprm,
 	func_module, func_firmware, func_post,
 	func_kexec_kernel, func_kexec_initramfs,
-	func_policy
+	func_kexec_cmdline, func_policy
 };
 
 static char *func_tokens[] = {
@@ -938,6 +941,7 @@ static char *func_tokens[] = {
 	"POST_SETATTR",
 	"KEXEC_KERNEL_CHECK",
 	"KEXEC_INITRAMFS_CHECK",
+	"KEXEC_CMDLINE_CHECK",
 	"POLICY_CHECK"
 };
 
@@ -1009,6 +1013,9 @@ static void policy_func_show(struct seq_file *m, enum ima_hooks func)
 	case KEXEC_INITRAMFS_CHECK:
 		seq_printf(m, pt(Opt_func), ft(func_kexec_initramfs));
 		break;
+	case KEXEC_CMDLINE_CHECK:
+		seq_printf(m, pt(Opt_func), ft(func_kexec_cmdline));
+		break;
 	case POLICY_CHECK:
 		seq_printf(m, pt(Opt_func), ft(func_policy));
 		break;
-- 
2.1.0