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From: Andrew Morton <akpm@linux-foundation.org>
To: akpm@linux-foundation.org, ast@kernel.org, ebiggers@google.com,
	gregkh@linuxfoundation.org, jeffv@google.com, jeyu@kernel.org,
	keescook@chromium.org, linux-mm@kvack.org, mcgrof@kernel.org,
	mm-commits@vger.kernel.org, neilb@suse.com,
	torvalds@linux-foundation.org
Subject: [patch 28/35] docs: admin-guide: document the kernel.modprobe sysctl
Date: Fri, 10 Apr 2020 14:33:50 -0700	[thread overview]
Message-ID: <20200410213350.o21mcrRmh%akpm@linux-foundation.org> (raw)
In-Reply-To: <20200410143047.bf34a933ce1affdc042c7c80@linux-foundation.org>

From: Eric Biggers <ebiggers@google.com>
Subject: docs: admin-guide: document the kernel.modprobe sysctl

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.

[ebiggers@google.com: v5]
  Link: http://lkml.kernel.org/r/20200318230515.171692-4-ebiggers@kernel.org
Link: http://lkml.kernel.org/r/20200312202552.241885-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Cc: Alexei Starovoitov <ast@kernel.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: Andrew Morton <akpm@linux-foundation.org>
---

 Documentation/admin-guide/sysctl/kernel.rst |   21 ++++++++++++++++++
 1 file changed, 21 insertions(+)

--- a/Documentation/admin-guide/sysctl/kernel.rst~docs-admin-guide-document-the-kernelmodprobe-sysctl
+++ a/Documentation/admin-guide/sysctl/kernel.rst
@@ -446,6 +446,27 @@ 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
 ============
_

  parent reply	other threads:[~2020-04-10 21:33 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-10 21:30 incoming Andrew Morton
2020-04-10 21:32 ` [patch 01/35] hfsplus: fix crash and filesystem corruption when deleting files Andrew Morton
2020-04-10 21:32 ` [patch 02/35] mm, memcg: do not high throttle allocators based on wraparound Andrew Morton
2020-04-10 21:32 ` [patch 03/35] mm, slab_common: fix a typo in comment "eariler"->"earlier" Andrew Morton
2020-04-10 21:32 ` [patch 04/35] docs: mm: slab.h: fix a broken cross-reference Andrew Morton
2020-04-10 21:32 ` [patch 05/35] mm/page_alloc.c: fix kernel-doc warning Andrew Morton
2020-04-10 21:32 ` [patch 06/35] mm/page_alloc: make pcpu_drain_mutex and pcpu_drain static Andrew Morton
2020-04-10 21:32 ` [patch 07/35] mm/gup: fix null pointer dereference detected by coverity Andrew Morton
2020-04-10 21:32 ` [patch 08/35] ocfs2: no need try to truncate file beyond i_size Andrew Morton
2020-04-10 21:32 ` [patch 09/35] mm: cma: NUMA node interface Andrew Morton
2020-04-10 21:32 ` [patch 10/35] mm: hugetlb: optionally allocate gigantic hugepages using cma Andrew Morton
2020-04-10 21:32 ` [patch 11/35] mm/mmap.c: initialize align_offset explicitly for vm_unmapped_area Andrew Morton
2020-04-10 21:32 ` [patch 12/35] mm/memory.c: refactor insert_page to prepare for batched-lock insert Andrew Morton
2020-04-10 21:32 ` [patch 13/35] mm: bring sparc pte_index() semantics inline with other platforms Andrew Morton
2020-04-10 21:32 ` [patch 14/35] mm: define pte_index as macro for x86 Andrew Morton
2020-04-10 21:33 ` [patch 15/35] mm/memory.c: add vm_insert_pages() Andrew Morton
2020-04-10 21:33 ` [patch 16/35] mm/vma: define a default value for VM_DATA_DEFAULT_FLAGS Andrew Morton
2020-04-10 21:33 ` [patch 17/35] mm/vma: introduce VM_ACCESS_FLAGS Andrew Morton
2020-04-10 21:33 ` [patch 18/35] mm/special: create generic fallbacks for pte_special() and pte_mkspecial() Andrew Morton
2020-04-10 21:33 ` [patch 19/35] mm/memory_hotplug: drop the flags field from struct mhp_restrictions Andrew Morton
2020-04-10 21:33 ` [patch 20/35] mm/memory_hotplug: rename mhp_restrictions to mhp_params Andrew Morton
2020-04-10 21:33 ` [patch 21/35] x86/mm: thread pgprot_t through init_memory_mapping() Andrew Morton
2020-04-10 21:33 ` [patch 22/35] x86/mm: introduce __set_memory_prot() Andrew Morton
2020-04-10 21:33 ` [patch 23/35] powerpc/mm: thread pgprot_t through create_section_mapping() Andrew Morton
2020-04-10 21:33 ` [patch 24/35] mm/memory_hotplug: add pgprot_t to mhp_params Andrew Morton
2020-04-10 21:33 ` [patch 25/35] mm/memremap: set caching mode for PCI P2PDMA memory to WC Andrew Morton
2020-04-10 21:33 ` [patch 26/35] kmod: make request_module() return an error when autoloading is disabled Andrew Morton
2020-04-10 21:33 ` [patch 27/35] fs/filesystems.c: downgrade user-reachable WARN_ONCE() to pr_warn_once() Andrew Morton
2020-04-10 21:33 ` Andrew Morton [this message]
2020-04-10 21:33 ` [patch 29/35] selftests: kmod: fix handling test numbers above 9 Andrew Morton
2020-04-10 21:33 ` [patch 30/35] selftests: kmod: test disabling module autoloading Andrew Morton
2020-04-10 21:34 ` [patch 31/35] change email address for Pali Rohár Andrew Morton
2020-04-10 21:34 ` [patch 32/35] drivers/dma/tegra20-apb-dma.c: fix platform_get_irq.cocci warnings Andrew Morton
2020-04-10 21:34 ` [patch 33/35] fs/seq_file.c: seq_read(): add info message about buggy .next functions Andrew Morton
2020-04-10 21:34 ` [patch 34/35] kernel/gcov/fs.c: gcov_seq_next() should increase position index Andrew Morton
2020-04-10 21:34 ` [patch 35/35] ipc/util.c: sysvipc_find_ipc() " Andrew Morton

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