Commit 2e72d51b authored by Kees Cook's avatar Kees Cook Committed by Rusty Russell
Browse files

security: introduce kernel_module_from_file hook

Now that kernel module origins can be reasoned about, provide a hook to
the LSMs to make policy decisions about the module file. This will let
Chrome OS enforce that loadable kernel modules can only come from its
read-only hash-verified root filesystem. Other LSMs can, for example,
read extended attributes for signatures, etc.
Signed-off-by: default avatarKees Cook <>
Acked-by: default avatarSerge E. Hallyn <>
Acked-by: default avatarEric Paris <>
Acked-by: default avatarMimi Zohar <>
Acked-by: default avatarJames Morris <>
Signed-off-by: default avatarRusty Russell <>
parent 2f3238ae
......@@ -694,6 +694,12 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
* userspace to load a kernel module with the given name.
* @kmod_name name of the module requested by the kernel
* Return 0 if successful.
* @kernel_module_from_file:
* Load a kernel module from userspace.
* @file contains the file structure pointing to the file containing
* 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.
* @task_fix_setuid:
* Update the module's state after setting one or more of the user
* identity attributes of the current process. The @flags parameter
......@@ -1508,6 +1514,7 @@ struct security_operations {
int (*kernel_act_as)(struct cred *new, u32 secid);
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 (*task_fix_setuid) (struct cred *new, const struct cred *old,
int flags);
int (*task_setpgid) (struct task_struct *p, pid_t pgid);
......@@ -1765,6 +1772,7 @@ void security_transfer_creds(struct cred *new, const struct cred *old);
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_task_fix_setuid(struct cred *new, const struct cred *old,
int flags);
int security_task_setpgid(struct task_struct *p, pid_t pgid);
......@@ -2278,6 +2286,11 @@ static inline int security_kernel_module_request(char *kmod_name)
return 0;
static inline int security_kernel_module_from_file(struct file *file)
return 0;
static inline int security_task_fix_setuid(struct cred *new,
const struct cred *old,
int flags)
......@@ -29,6 +29,7 @@
#include <linux/vmalloc.h>
#include <linux/elf.h>
#include <linux/proc_fs.h>
#include <linux/security.h>
#include <linux/seq_file.h>
#include <linux/syscalls.h>
#include <linux/fcntl.h>
......@@ -2485,10 +2486,16 @@ static int elf_header_check(struct load_info *info)
static int copy_module_from_user(const void __user *umod, unsigned long len,
struct load_info *info)
int err;
info->len = len;
if (info->len < sizeof(*(info->hdr)))
return -ENOEXEC;
err = security_kernel_module_from_file(NULL);
if (err)
return err;
/* Suck in entire file: we'll want most of it. */
info->hdr = vmalloc(info->len);
if (!info->hdr)
......@@ -2515,6 +2522,10 @@ static int copy_module_from_fd(int fd, struct load_info *info)
if (!file)
return -ENOEXEC;
err = security_kernel_module_from_file(file);
if (err)
goto out;
err = vfs_getattr(file->f_vfsmnt, file->f_dentry, &stat);
if (err)
goto out;
......@@ -395,6 +395,11 @@ static int cap_kernel_module_request(char *kmod_name)
return 0;
static int cap_kernel_module_from_file(struct file *file)
return 0;
static int cap_task_setpgid(struct task_struct *p, pid_t pgid)
return 0;
......@@ -967,6 +972,7 @@ void __init security_fixup_ops(struct security_operations *ops)
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_module_request);
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_setpgid);
set_to_cap_if_null(ops, task_getpgid);
......@@ -820,6 +820,11 @@ int security_kernel_module_request(char *kmod_name)
return security_ops->kernel_module_request(kmod_name);
int security_kernel_module_from_file(struct file *file)
return security_ops->kernel_module_from_file(file);
int security_task_fix_setuid(struct cred *new, const struct cred *old,
int flags)
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