security: define kernel_read_file hook

The kernel_read_file security hook is called prior to reading the file
into memory.

Changelog v4+:
- export security_kernel_read_file()

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>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>

3 files changed, 21 insertions, 0 deletions

diff --git a/include/linux/ima.h b/include/linux/ima.h
index 7aea4863c244..6adcaea8101c 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -19,6 +19,7 @@ extern int ima_file_check(struct file *file, int mask, int opened);
 extern void ima_file_free(struct file *file);
 extern int ima_file_mmap(struct file *file, unsigned long prot);
 extern int ima_module_check(struct file *file);
+extern int ima_read_file(struct file *file, enum kernel_read_file_id id);
 extern int ima_post_read_file(struct file *file, void *buf, loff_t size,
 			      enum kernel_read_file_id id);
 
@@ -48,6 +49,11 @@ static inline int ima_module_check(struct file *file)
 	return 0;
 }
 
+static inline int ima_read_file(struct file *file, enum kernel_read_file_id id)
+{
+	return 0;
+}
+
 static inline int ima_post_read_file(struct file *file, void *buf, loff_t size,
 				     enum kernel_read_file_id id)
 {
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 7d04a1220223..d32b7bd13635 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -552,6 +552,12 @@
  *	the kernel module to load. If the module is being loaded from a blob,
  *	this argument will be NULL.
  *	Return 0 if permission is granted.
+ * @kernel_read_file:
+ *	Read a file specified by userspace.
+ *	@file contains the file structure pointing to the file being read
+ *	by the kernel.
+ *	@id kernel read file identifier
+ *	Return 0 if permission is granted.
  * @kernel_post_read_file:
  *	Read a file specified by userspace.
  *	@file contains the file structure pointing to the file being read
@@ -1455,6 +1461,7 @@ union security_list_options {
 	int (*kernel_create_files_as)(struct cred *new, struct inode *inode);
 	int (*kernel_module_request)(char *kmod_name);
 	int (*kernel_module_from_file)(struct file *file);
+	int (*kernel_read_file)(struct file *file, enum kernel_read_file_id id);
 	int (*kernel_post_read_file)(struct file *file, char *buf, loff_t size,
 				     enum kernel_read_file_id id);
 	int (*task_fix_setuid)(struct cred *new, const struct cred *old,
@@ -1715,6 +1722,7 @@ struct security_hook_heads {
 	struct list_head cred_transfer;
 	struct list_head kernel_act_as;
 	struct list_head kernel_create_files_as;
+	struct list_head kernel_read_file;
 	struct list_head kernel_post_read_file;
 	struct list_head kernel_module_request;
 	struct list_head kernel_module_from_file;
diff --git a/include/linux/security.h b/include/linux/security.h
index cee1349e1155..071fb747fdbb 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -302,6 +302,7 @@ int security_kernel_act_as(struct cred *new, u32 secid);
 int security_kernel_create_files_as(struct cred *new, struct inode *inode);
 int security_kernel_module_request(char *kmod_name);
 int security_kernel_module_from_file(struct file *file);
+int security_kernel_read_file(struct file *file, enum kernel_read_file_id id);
 int security_kernel_post_read_file(struct file *file, char *buf, loff_t size,
 				   enum kernel_read_file_id id);
 int security_task_fix_setuid(struct cred *new, const struct cred *old,
@@ -863,6 +864,12 @@ static inline int security_kernel_module_from_file(struct file *file)
 	return 0;
 }
 
+static inline int security_kernel_read_file(struct file *file,
+					    enum kernel_read_file_id id)
+{
+	return 0;
+}
+
 static inline int security_kernel_post_read_file(struct file *file,
 						 char *buf, loff_t size,
 						 enum kernel_read_file_id id)