| Message ID | 20200318230515.171692-4-ebiggers@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | module autoloading fixes and cleanups | expand |
Andrew, On Wed, Mar 18, 2020 at 04:05:13PM -0700, Eric Biggers wrote: > From: Eric Biggers <ebiggers@google.com> > > Document the kernel.modprobe sysctl in the same place that all the other > kernel.* sysctls are documented. Make sure to mention how to use this > sysctl to completely disable module autoloading, and how this sysctl > relates to CONFIG_STATIC_USERMODEHELPER. > > Cc: Alexei Starovoitov <ast@kernel.org> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Cc: Jeff Vander Stoep <jeffv@google.com> > Cc: Jessica Yu <jeyu@kernel.org> > Cc: Kees Cook <keescook@chromium.org> > Cc: Luis Chamberlain <mcgrof@kernel.org> > Cc: NeilBrown <neilb@suse.com> > Signed-off-by: Eric Biggers <ebiggers@google.com> > --- > Documentation/admin-guide/sysctl/kernel.rst | 25 ++++++++++++++++++++- > 1 file changed, 24 insertions(+), 1 deletion(-) > I just noticed there's already a patch going into 5.7 through the docs tree (https://lkml.kernel.org/lkml/20200329172713.206afe79@lwn.net/) that creates the documentation for this sysctl: commit 0317c5371e6a9b71a2e25b47013dd5c62d55d1a6 Author: Stephen Kitt <steve@sk2.org> Date: Tue Feb 18 13:59:17 2020 +0100 docs: merge debugging-modules.txt into sysctl/kernel.rst It looks for -mm, you resolved the conflict by changing my patch to add the documentation to a different location in the file. But that's not correct as it results in this sysctl being documented twice. Perhaps just drop this patch for now, but keep patches 1-2 and 4-5? I can rebase and resend this documentation patch later. - Eric
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index def074807cee9..e3c15660ee5d9 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -49,7 +49,7 @@ show up in /proc/sys/kernel: - kexec_load_disabled - kptr_restrict - l2cr [ PPC only ] -- modprobe ==> Documentation/debugging-modules.txt +- modprobe - modules_disabled - msg_next_id [ sysv ipc ] - msgmax @@ -444,6 +444,29 @@ l2cr: (PPC only) This flag controls the L2 cache of G3 processor boards. If 0, the cache is disabled. Enabled if nonzero. +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. + +Also see Documentation/debugging-modules.txt. modules_disabled: =================