[PATCH v2 5/9] ima: based on policy require signed kexec kernel images

[Mimi Zohar]

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 <zo...@linux.vnet.ibm.com>
Cc: Eric Biederman <ebied...@xmission.com>
Cc: Luis R. Rodriguez <mcg...@kernel.org>
Cc: Kees Cook <keesc...@chromium.org>
Cc: David Howells <dhowe...@redhat.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 354bb5716ce3..78c15264b17b 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -232,6 +232,7 @@ 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 83f84928ad76..7e1a127f18fe 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -442,6 +442,15 @@ 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 8bbc18eb07eb..c27f6993b07a 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