module: replace copy_module_from_fd with kernel version

Replace copy_module_from_fd() with kernel_read_file_from_fd().

Although none of the upstreamed LSMs define a kernel_module_from_file
hook, IMA is called, based on policy, to prevent unsigned kernel modules
from being loaded by the original kernel module syscall and to
measure/appraise signed kernel modules.

The security function security_kernel_module_from_file() was called prior
to reading a kernel module.  Preventing unsigned kernel modules from being
loaded by the original kernel module syscall remains on the pre-read
kernel_read_file() security hook.  Instead of reading the kernel module
twice, once for measuring/appraising and again for loading the kernel
module, the signature validation is moved to the kernel_post_read_file()
security hook.

This patch removes the security_kernel_module_from_file() hook and security
call.

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Luis R. Rodriguez <mcgrof@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>

2 files changed, 13 insertions, 34 deletions

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index bbb80df..5da0b9c 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -316,28 +316,6 @@ int ima_file_check(struct file *file, int mask, int opened)
 EXPORT_SYMBOL_GPL(ima_file_check);
 
 /**
- * ima_module_check - based on policy, collect/store/appraise measurement.
- * @file: pointer to the file to be measured/appraised
- *
- * Measure/appraise kernel modules based on policy.
- *
- * On success return 0.  On integrity appraisal error, assuming the file
- * is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
- */
-int ima_module_check(struct file *file)
-{
-	if (!file) {
-#ifndef CONFIG_MODULE_SIG_FORCE
-		if ((ima_appraise & IMA_APPRAISE_MODULES) &&
-		    (ima_appraise & IMA_APPRAISE_ENFORCE))
-			return -EACCES;	/* INTEGRITY_UNKNOWN */
-#endif
-		return 0;	/* We rely on module signature checking */
-	}
-	return process_measurement(file, NULL, 0, MAY_EXEC, MODULE_CHECK, 0);
-}
-
-/**
  * ima_read_file - pre-measure/appraise hook decision based on policy
  * @file: pointer to the file to be measured/appraised/audit
  * @read_id: caller identifier
@@ -350,6 +328,14 @@ int ima_module_check(struct file *file)
  */
 int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
 {
+	if (!file && read_id == READING_MODULE) {
+#ifndef CONFIG_MODULE_SIG_FORCE
+		if ((ima_appraise & IMA_APPRAISE_MODULES) &&
+		    (ima_appraise & IMA_APPRAISE_ENFORCE))
+			return -EACCES;	/* INTEGRITY_UNKNOWN */
+#endif
+		return 0;	/* We rely on module signature checking */
+	}
 	return 0;
 }
 
@@ -378,6 +364,9 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
 		return 0;
 	}
 
+	if (!file && read_id == READING_MODULE) /* MODULE_SIG_FORCE enabled */
+		return 0;
+
 	if (!file || !buf || size == 0) { /* should never happen */
 		if (ima_appraise & IMA_APPRAISE_ENFORCE)
 			return -EACCES;
@@ -386,6 +375,8 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
 
 	if (read_id == READING_FIRMWARE)
 		func = FIRMWARE_CHECK;
+	else if (read_id == READING_MODULE)
+		func = MODULE_CHECK;
 
 	return process_measurement(file, buf, size, MAY_READ, func, 0);
 }
diff --git a/security/security.c b/security/security.c
index 8e699f9..3644b034 100644
--- a/security/security.c
+++ b/security/security.c
@@ -889,16 +889,6 @@ int security_kernel_module_request(char *kmod_name)
 	return call_int_hook(kernel_module_request, 0, kmod_name);
 }
 
-int security_kernel_module_from_file(struct file *file)
-{
-	int ret;
-
-	ret = call_int_hook(kernel_module_from_file, 0, file);
-	if (ret)
-		return ret;
-	return ima_module_check(file);
-}
-
 int security_kernel_read_file(struct file *file, enum kernel_read_file_id id)
 {
 	int ret;
@@ -1705,8 +1695,6 @@ struct security_hook_heads security_hook_heads = {
 		LIST_HEAD_INIT(security_hook_heads.kernel_create_files_as),
 	.kernel_module_request =
 		LIST_HEAD_INIT(security_hook_heads.kernel_module_request),
-	.kernel_module_from_file =
-		LIST_HEAD_INIT(security_hook_heads.kernel_module_from_file),
 	.kernel_read_file =
 		LIST_HEAD_INIT(security_hook_heads.kernel_read_file),
 	.kernel_post_read_file =