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authorMimi Zohar <zohar@linux.vnet.ibm.com>2018-07-13 21:05:58 +0300
committerJames Morris <james.morris@microsoft.com>2018-07-16 22:31:57 +0300
commit16c267aac86b463b1fcccd43c89f4c8e5c5c86fa (patch)
tree550e6fcb00d732a3c018b3258302f8ffd61a4379 /security
parenta210fd32a46bae6d05b43860fe3b47732501d63b (diff)
downloadlinux-16c267aac86b463b1fcccd43c89f4c8e5c5c86fa.tar.xz
ima: based on policy require signed kexec kernel images
The original kexec_load syscall can not verify file signatures, nor can the kexec image be measured. Based on policy, deny the kexec_load syscall. Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com> Cc: Eric Biederman <ebiederm@xmission.com> Cc: Kees Cook <keescook@chromium.org> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: James Morris <james.morris@microsoft.com>
Diffstat (limited to 'security')
-rw-r--r--security/integrity/ima/ima.h1
-rw-r--r--security/integrity/ima/ima_main.c27
-rw-r--r--security/integrity/ima/ima_policy.c2
-rw-r--r--security/security.c7
4 files changed, 36 insertions, 1 deletions
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 dca44cf7838e..71fecfef0939 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -496,6 +496,33 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
MAY_READ, func, 0);
}
+/**
+ * ima_load_data - appraise decision based on policy
+ * @id: kernel load data caller identifier
+ *
+ * Callers of this LSM hook can not measure, appraise, or audit the
+ * data provided by userspace. Enforce policy rules requring a file
+ * signature (eg. kexec'ed kernel image).
+ *
+ * For permission return 0, otherwise return -EACCES.
+ */
+int ima_load_data(enum kernel_load_data_id id)
+{
+ if ((ima_appraise & IMA_APPRAISE_ENFORCE) != IMA_APPRAISE_ENFORCE)
+ return 0;
+
+ switch (id) {
+ case LOADING_KEXEC_IMAGE:
+ if (ima_appraise & IMA_APPRAISE_KEXEC) {
+ pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n");
+ return -EACCES; /* INTEGRITY_UNKNOWN */
+ }
+ default:
+ break;
+ }
+ return 0;
+}
+
static int __init init_ima(void)
{
int error;
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index cdcc9a7b4e24..d5b4958decc5 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;
}
diff --git a/security/security.c b/security/security.c
index c2de2f134854..4927e7cc7d96 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1058,7 +1058,12 @@ EXPORT_SYMBOL_GPL(security_kernel_post_read_file);
int security_kernel_load_data(enum kernel_load_data_id id)
{
- return call_int_hook(kernel_load_data, 0, id);
+ int ret;
+
+ ret = call_int_hook(kernel_load_data, 0, id);
+ if (ret)
+ return ret;
+ return ima_load_data(id);
}
int security_task_fix_setuid(struct cred *new, const struct cred *old,