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Commit 39eeb4fb authored by Mimi Zohar's avatar Mimi Zohar
Browse files

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: default avatarMimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Acked-by: default avatarLuis R. Rodriguez <mcgrof@kernel.org>
Acked-by: default avatarCasey Schaufler <casey@schaufler-ca.com>
parent e40ba6d5

fs/exec.c

+4 −0
Original line number Diff line number Diff line
@@ -842,6 +842,10 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size, 
	if (!S_ISREG(file_inode(file)->i_mode) || max_size < 0)

		return -EINVAL;



	ret = security_kernel_read_file(file, id);

	if (ret)

		return ret;



	i_size = i_size_read(file_inode(file));

	if (max_size > 0 && i_size > max_size)

		return -EFBIG;

include/linux/ima.h

+6 −0
Original line number Diff line number Diff line
@@ -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)

{

include/linux/lsm_hooks.h

+8 −0
Original line number Diff line number Diff line
@@ -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;

include/linux/security.h

+7 −0
Original line number Diff line number Diff line
@@ -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)

security/integrity/ima/ima_main.c

+16 −0
Original line number Diff line number Diff line
@@ -337,6 +337,22 @@ int ima_module_check(struct file *file) 
	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

 *

 * Permit reading a file based on policy. The policy rules are written

 * in terms of the policy identifier.  Appraising the integrity of

 * a file requires a file descriptor.

 *

 * For permission return 0, otherwise return -EACCES.

 */

int ima_read_file(struct file *file, enum kernel_read_file_id read_id)

{

	return 0;

}



/**

 * ima_post_read_file - in memory collect/appraise/audit measurement

 * @file: pointer to the file to be measured/appraised/audit