Commit 13752fe2 authored by Kees Cook's avatar Kees Cook

security: introduce kernel_fw_from_file hook

In order to validate the contents of firmware being loaded, there must be
a hook to evaluate any loaded firmware that wasn't built into the kernel
itself. Without this, there is a risk that a root user could load malicious
firmware designed to mount an attack against kernel memory (e.g. via DMA).
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 7d8b6c63
...@@ -702,6 +702,15 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts) ...@@ -702,6 +702,15 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
* @inode points to the inode to use as a reference. * @inode points to the inode to use as a reference.
* The current task must be the one that nominated @inode. * The current task must be the one that nominated @inode.
* Return 0 if successful. * Return 0 if successful.
* @kernel_fw_from_file:
* Load firmware from userspace (not called for built-in firmware).
* @file contains the file structure pointing to the file containing
* the firmware to load. This argument will be NULL if the firmware
* was loaded via the uevent-triggered blob-based interface exposed
* by CONFIG_FW_LOADER_USER_HELPER.
* @buf pointer to buffer containing firmware contents.
* @size length of the firmware contents.
* Return 0 if permission is granted.
* @kernel_module_request: * @kernel_module_request:
* Ability to trigger the kernel to automatically upcall to userspace for * Ability to trigger the kernel to automatically upcall to userspace for
* userspace to load a kernel module with the given name. * userspace to load a kernel module with the given name.
...@@ -1568,6 +1577,7 @@ struct security_operations { ...@@ -1568,6 +1577,7 @@ struct security_operations {
void (*cred_transfer)(struct cred *new, const struct cred *old); void (*cred_transfer)(struct cred *new, const struct cred *old);
int (*kernel_act_as)(struct cred *new, u32 secid); int (*kernel_act_as)(struct cred *new, u32 secid);
int (*kernel_create_files_as)(struct cred *new, struct inode *inode); int (*kernel_create_files_as)(struct cred *new, struct inode *inode);
int (*kernel_fw_from_file)(struct file *file, char *buf, size_t size);
int (*kernel_module_request)(char *kmod_name); int (*kernel_module_request)(char *kmod_name);
int (*kernel_module_from_file)(struct file *file); int (*kernel_module_from_file)(struct file *file);
int (*task_fix_setuid) (struct cred *new, const struct cred *old, int (*task_fix_setuid) (struct cred *new, const struct cred *old,
...@@ -1840,6 +1850,7 @@ int security_prepare_creds(struct cred *new, const struct cred *old, gfp_t gfp); ...@@ -1840,6 +1850,7 @@ int security_prepare_creds(struct cred *new, const struct cred *old, gfp_t gfp);
void security_transfer_creds(struct cred *new, const struct cred *old); void security_transfer_creds(struct cred *new, const struct cred *old);
int security_kernel_act_as(struct cred *new, u32 secid); 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_create_files_as(struct cred *new, struct inode *inode);
int security_kernel_fw_from_file(struct file *file, char *buf, size_t size);
int security_kernel_module_request(char *kmod_name); int security_kernel_module_request(char *kmod_name);
int security_kernel_module_from_file(struct file *file); int security_kernel_module_from_file(struct file *file);
int security_task_fix_setuid(struct cred *new, const struct cred *old, int security_task_fix_setuid(struct cred *new, const struct cred *old,
...@@ -2366,6 +2377,12 @@ static inline int security_kernel_create_files_as(struct cred *cred, ...@@ -2366,6 +2377,12 @@ static inline int security_kernel_create_files_as(struct cred *cred,
return 0; return 0;
} }
static inline int security_kernel_fw_from_file(struct file *file,
char *buf, size_t size)
{
return 0;
}
static inline int security_kernel_module_request(char *kmod_name) static inline int security_kernel_module_request(char *kmod_name)
{ {
return 0; return 0;
......
...@@ -401,6 +401,11 @@ static int cap_kernel_create_files_as(struct cred *new, struct inode *inode) ...@@ -401,6 +401,11 @@ static int cap_kernel_create_files_as(struct cred *new, struct inode *inode)
return 0; return 0;
} }
static int cap_kernel_fw_from_file(struct file *file, char *buf, size_t size)
{
return 0;
}
static int cap_kernel_module_request(char *kmod_name) static int cap_kernel_module_request(char *kmod_name)
{ {
return 0; return 0;
...@@ -1015,6 +1020,7 @@ void __init security_fixup_ops(struct security_operations *ops) ...@@ -1015,6 +1020,7 @@ void __init security_fixup_ops(struct security_operations *ops)
set_to_cap_if_null(ops, cred_transfer); set_to_cap_if_null(ops, cred_transfer);
set_to_cap_if_null(ops, kernel_act_as); set_to_cap_if_null(ops, kernel_act_as);
set_to_cap_if_null(ops, kernel_create_files_as); set_to_cap_if_null(ops, kernel_create_files_as);
set_to_cap_if_null(ops, kernel_fw_from_file);
set_to_cap_if_null(ops, kernel_module_request); set_to_cap_if_null(ops, kernel_module_request);
set_to_cap_if_null(ops, kernel_module_from_file); set_to_cap_if_null(ops, kernel_module_from_file);
set_to_cap_if_null(ops, task_fix_setuid); set_to_cap_if_null(ops, task_fix_setuid);
......
...@@ -845,6 +845,12 @@ int security_kernel_create_files_as(struct cred *new, struct inode *inode) ...@@ -845,6 +845,12 @@ int security_kernel_create_files_as(struct cred *new, struct inode *inode)
return security_ops->kernel_create_files_as(new, inode); return security_ops->kernel_create_files_as(new, inode);
} }
int security_kernel_fw_from_file(struct file *file, char *buf, size_t size)
{
return security_ops->kernel_fw_from_file(file, buf, size);
}
EXPORT_SYMBOL_GPL(security_kernel_fw_from_file);
int security_kernel_module_request(char *kmod_name) int security_kernel_module_request(char *kmod_name)
{ {
return security_ops->kernel_module_request(kmod_name); return security_ops->kernel_module_request(kmod_name);
......
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