diff options
| -rw-r--r-- | Documentation/admin-guide/sysctl/kernel.rst | 47 |
1 files changed, 19 insertions, 28 deletions
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index 39c95c0e13d3..0d427fd10941 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -390,9 +390,17 @@ When ``kptr_restrict`` is set to 2, kernel pointers printed using modprobe ======== -This gives the full path of the modprobe command which the kernel will -use to load modules. This can be used to debug module loading -requests:: +The full path to the usermode helper for autoloading kernel modules, +by default "/sbin/modprobe". This binary is executed when the kernel +requests a module. For example, if userspace passes an unknown +filesystem type to mount(), then the kernel will automatically request +the corresponding filesystem module by executing this usermode helper. +This usermode helper should insert the needed module into the kernel. + +This sysctl only affects module autoloading. It has no effect on the +ability to explicitly insert modules. + +This sysctl can be used to debug module loading requests:: echo '#! /bin/sh' > /tmp/modprobe echo 'echo "$@" >> /tmp/modprobe.log' >> /tmp/modprobe @@ -400,10 +408,15 @@ requests:: chmod a+x /tmp/modprobe echo /tmp/modprobe > /proc/sys/kernel/modprobe -This only applies when the *kernel* is requesting that the module be -loaded; it won't have any effect if the module is being loaded -explicitly using ``modprobe`` from userspace. +Alternatively, if this sysctl is set to the empty string, then module +autoloading is completely disabled. The kernel will not try to +execute a usermode helper at all, nor will it call the +kernel_module_request LSM hook. +If CONFIG_STATIC_USERMODEHELPER=y is set in the kernel configuration, +then the configured static usermode helper overrides this sysctl, +except that the empty string is still accepted to completely disable +module autoloading as described above. modules_disabled ================ @@ -446,28 +459,6 @@ Notes: successful IPC object allocation. If an IPC object allocation syscall fails, it is undefined if the value remains unmodified or is reset to -1. -modprobe: -========= - -The path to the usermode helper for autoloading kernel modules, by -default "/sbin/modprobe". This binary is executed when the kernel -requests a module. For example, if userspace passes an unknown -filesystem type to mount(), then the kernel will automatically request -the corresponding filesystem module by executing this usermode helper. -This usermode helper should insert the needed module into the kernel. - -This sysctl only affects module autoloading. It has no effect on the -ability to explicitly insert modules. - -If this sysctl is set to the empty string, then module autoloading is -completely disabled. The kernel will not try to execute a usermode -helper at all, nor will it call the kernel_module_request LSM hook. - -If CONFIG_STATIC_USERMODEHELPER=y is set in the kernel configuration, -then the configured static usermode helper overrides this sysctl, -except that the empty string is still accepted to completely disable -module autoloading as described above. - nmi_watchdog ============ |