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From: Mimi Zohar <zohar@linux.vnet.ibm.com>
To: linux-integrity@vger.kernel.org
Cc: Eric Biederman <ebiederm@xmission.com>,
	David Howells <dhowells@redhat.com>,
	Mimi Zohar <zohar@linux.vnet.ibm.com>,
	linux-security-module@vger.kernel.org, kexec@lists.infradead.org,
	linux-kernel@vger.kernel.org, Kees Cook <keescook@chromium.org>,
	Matthew Garrett <mjg59@google.com>
Subject: [PATCH 3/3] ima: based on policy require signed kexec kernel images
Date: Thu, 10 May 2018 21:36:48 -0400	[thread overview]
Message-ID: <1526002608-27474-4-git-send-email-zohar@linux.vnet.ibm.com> (raw)
In-Reply-To: <1526002608-27474-1-git-send-email-zohar@linux.vnet.ibm.com>

The original kexec_load syscall can not verify file signatures.  This
patch differentiates between the kexec_load and kexec_file_load
syscalls.

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Matthew Garrett <mjg59@google.com>
---
 security/integrity/ima/ima.h        | 1 +
 security/integrity/ima/ima_main.c   | 9 +++++++++
 security/integrity/ima/ima_policy.c | 2 ++
 3 files changed, 12 insertions(+)

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 35fe91aa1fc9..03c9c37ee345 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -233,6 +233,7 @@ int ima_policy_show(struct seq_file *m, void *v);
 #define IMA_APPRAISE_MODULES	0x08
 #define IMA_APPRAISE_FIRMWARE	0x10
 #define IMA_APPRAISE_POLICY	0x20
+#define IMA_APPRAISE_KEXEC	0x40
 
 #ifdef CONFIG_IMA_APPRAISE
 int ima_appraise_measurement(enum ima_hooks func,
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 74d0bd7e76d7..754ece08e1c6 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -444,6 +444,15 @@ int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
 		}
 		return 0;	/* We rely on module signature checking */
 	}
+
+	if (!file && read_id == READING_KEXEC_IMAGE) {
+		if ((ima_appraise & IMA_APPRAISE_KEXEC) &&
+		    (ima_appraise & IMA_APPRAISE_ENFORCE)) {
+			pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file syscall.\n");
+			return -EACCES;	/* INTEGRITY_UNKNOWN */
+		}
+		return 0;
+	}
 	return 0;
 }
 
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index df3e45878a87..a9e96a884867 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -448,6 +448,8 @@ static int ima_appraise_flag(enum ima_hooks func)
 		return IMA_APPRAISE_FIRMWARE;
 	else if (func == POLICY_CHECK)
 		return IMA_APPRAISE_POLICY;
+	else if (func == KEXEC_KERNEL_CHECK)
+		return IMA_APPRAISE_KEXEC;
 	return 0;
 }
 
-- 
2.7.5

  parent reply	other threads:[~2018-05-11  1:37 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-11  1:36 [PATCH 0/3] kexec: limit kexec_load syscall Mimi Zohar
2018-05-11  1:36 ` [PATCH 1/3] ima: based on the "secure_boot" policy limit syscalls Mimi Zohar
2018-05-11  1:36 ` [PATCH 2/3] kexec: call LSM hook for kexec_load syscall Mimi Zohar
2018-05-11  1:36 ` Mimi Zohar [this message]
  -- strict thread matches above, loose matches on Subject: below --
2018-04-12 22:41 [PATCH 0/3] kexec: limit " Mimi Zohar
2018-04-12 22:41 ` [PATCH 3/3] ima: based on policy require signed kexec kernel images Mimi Zohar

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