Provided by: manpages-dev_3.54-1ubuntu1_all bug


       init_module, finit_module - load a kernel module


       int init_module(void *module_image, unsigned long len,
                       const char *param_values);

       int finit_module(int fd, const char *param_values,
                        int flags);

       Note: There are no glibc wrappers for these system calls; see NOTES.


       init_module()  loads  an  ELF  image  into  kernel  space,  performs  any necessary symbol
       relocations, initializes module parameters to values provided by the caller, and then runs
       the module's init function.  This system call requires privilege.

       The module_image argument points to a buffer containing the binary image to be loaded; len
       specifies the size of that buffer.  The module image should be a valid  ELF  image,  built
       for the running kernel.

       The  param_values  argument  is  a string containing space-delimited specifications of the
       values  for  module  parameters  (defined  inside  the  module  using  module_param()  and
       module_param_array()).   The  kernel  parses  this  string  and  initializes the specified
       parameters.  Each of the parameter specifications has the form:


       The parameter name is one of those defined within the module using module_param() (see the
       Linux kernel source file include/linux/moduleparam.h).  The parameter value is optional in
       the case of bool and invbool parameters.  Values for array parameters are specified  as  a
       comma-separated list.

       The  finit_module()  system  call is like init_module(), but reads the module to be loaded
       from the file descriptor fd.  It is useful when the authenticity of a kernel module can be
       determined  from  its  location  in  the  filesystem; in cases where that is possible, the
       overhead of using cryptographically signed modules to  determine  the  authenticity  of  a
       module can be avoided.  The param_values argument is as for init_module().

       The  flags  argument  modifies  the  operation  of finit_module().  It is a bit mask value
       created by ORing together zero or more of the following flags:

              Ignore symbol version hashes.

              Ignore kernel version magic.

       There are some safety checks built into a module to ensure  that  it  matches  the  kernel
       against  which  it  is  loaded.   These  checks  are recorded when the module is built and
       verified when the module is  loaded.   First,  the  module  records  a  "vermagic"  string
       containing  the  kernel  version  number  and  prominent  features (such as the CPU type).
       Second, if the module was built with the CONFIG_MODVERSIONS configuration option  enabled,
       a  version  hash  is  recorded for each symbol the module uses.  This hash is based on the
       types of the arguments and return value for the function named by  the  symbol.   In  this
       case,  the  kernel  version  number within the "vermagic" string is ignored, as the symbol
       version hashes are assumed to be sufficiently reliable.

       Using the MODULE_INIT_IGNORE_VERMAGIC flag indicates that the "vermagic" string is  to  be
       ignored,  and  the  MODULE_INIT_IGNORE_MODVERSIONS  flag indicates that the symbol version
       hashes are to be ignored.  If  the  kernel  is  built  to  permit  forced  loading  (i.e.,
       configured  with  CONFIG_MODULE_FORCE_LOAD), then loading will continue, otherwise it will
       fail with ENOEXEC as expected for malformed modules.


       On success, these system calls return 0.  On error,  -1  is  returned  and  errno  is  set


       EBADMSG (since Linux 3.7)
              Module signature is misformatted.

       EBUSY  Timeout while trying to resolve a symbol reference by this module.

       EFAULT An address argument referred to a location that is outside the process's accessible
              address space.

       ENOKEY (since Linux 3.7)
              Module signature is invalid or the kernel does not have  a  key  for  this  module.
              This    error    is   returned   only   if   the   kernel   was   configured   with
              CONFIG_MODULE_SIG_FORCE; if the kernel was not configured with this option, then an
              invalid or unsigned module simply taints the kernel.

       ENOMEM Out of memory.

       EPERM  The  caller  was  not  privileged  (did not have the CAP_SYS_MODULE capability), or
              module loading is disabled (see /proc/sys/kernel/modules_disabled in proc(5)).

       The following errors may additionally occur for init_module():

       EEXIST A module with this name is already loaded.

       EINVAL param_values is invalid, or some part of the ELF  image  in  module_image  contains

              The  binary  image supplied in module_image is not an ELF image, or is an ELF image
              that is invalid or for a different architecture.

       The following errors may additionally occur for finit_module():

       EBADF  The file referred to by fd is not opened for reading.

       EFBIG  The file referred to by fd is too large.

       EINVAL flags is invalid.

              fd does not refer to an open file.

       In addition to the above errors, if the module's init function is executed and returns  an
       error,  then  init_module() or finit_module() fails and errno is set to the value returned
       by the init function.


       finit_module () is available since Linux 3.8.


       init_module() and finit_module() are Linux-specific.


       Glibc does not provide a wrapper for these system calls; call them using syscall(2).

       Information about currently loaded modules can be found in /proc/modules and in  the  file
       trees under the per-module subdirectories under /sys/module.

       See  the  Linux  kernel  source  file  include/linux/module.h  for  some useful background

   Linux 2.4 and earlier
       In Linux 2.4 and earlier, the init_module() system call was rather different:

           #include <linux/module.h>

           int init_module(const char *name, struct module *image);

       (User-space applications can detect which version of init_module() is available by calling
       query_module(); the latter call fails with the error ENOSYS on Linux 2.6 and later.)

       The  older version of the system call loads the relocated module image pointed to by image
       into kernel space and runs the module's init function.   The  caller  is  responsible  for
       providing  the  relocated  image  (since Linux 2.6, the init_module() system call does the

       The module image begins with a module structure and  is  followed  by  code  and  data  as
       appropriate.  Since Linux 2.2, the module structure is defined as follows:

           struct module {
               unsigned long         size_of_struct;
               struct module        *next;
               const char           *name;
               unsigned long         size;
               long                  usecount;
               unsigned long         flags;
               unsigned int          nsyms;
               unsigned int          ndeps;
               struct module_symbol *syms;
               struct module_ref    *deps;
               struct module_ref    *refs;
               int                 (*init)(void);
               void                (*cleanup)(void);
               const struct exception_table_entry *ex_table_start;
               const struct exception_table_entry *ex_table_end;
           #ifdef __alpha__
               unsigned long gp;

       All  of  the  pointer  fields,  with the exception of next and refs, are expected to point
       within the module body and be initialized  as  appropriate  for  kernel  space,  that  is,
       relocated with the rest of the module.


       create_module(2), delete_module(2), query_module(2), lsmod(8), modprobe(8)


       This  page  is  part of release 3.54 of the Linux man-pages project.  A description of the
       project,    and    information    about    reporting    bugs,    can    be    found     at