linux.git/net/sysctl_net.c, branch v6.18.21

sysctl: Remove check for sentinel element in ctl_table arrays

2024-06-13T08:50:52+00:00

Use ARRAY_SIZE exclusively by removing the check to ->procname in the
stopping criteria of the loops traversing ctl_table arrays. This commit
finalizes the removal of the sentinel elements at the end of ctl_table
arrays which reduces the build time size and run time memory bloat by
~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)

Remove the entry->procname evaluation from the for loop stopping
criteria in sysctl and sysctl_net.

Signed-off-by: Joel Granados

sysctl: treewide: constify argument ctl_table_root::permissions(table)

2024-04-24T07:43:54+00:00

The permissions callback should not modify the ctl_table. Enforce this
expectation via the typesystem. This is a step to put "struct ctl_table"
into .rodata throughout the kernel.

The patch was created with the following coccinelle script:

  @@
  identifier func, head, ctl;
  @@

  int func(
    struct ctl_table_header *head,
  - struct ctl_table *ctl)
  + const struct ctl_table *ctl)
  { ... }

(insert_entry() from fs/proc/proc_sysctl.c is a false-positive)

No additional occurrences of '.permissions =' were found after a
tree-wide search for places missed by the conccinelle script.

Reviewed-by: Joel Granados 
Signed-off-by: Thomas Weißschuh 
Signed-off-by: Joel Granados

sysctl: treewide: drop unused argument ctl_table_root::set_ownership(table)

2024-04-24T07:43:54+00:00

Remove the 'table' argument from set_ownership as it is never used. This
change is a step towards putting "struct ctl_table" into .rodata and
eventually having sysctl core only use "const struct ctl_table".

The patch was created with the following coccinelle script:

  @@
  identifier func, head, table, uid, gid;
  @@

  void func(
    struct ctl_table_header *head,
  - struct ctl_table *table,
    kuid_t *uid, kgid_t *gid)
  { ... }

No additional occurrences of 'set_ownership' were found after doing a
tree-wide search.

Reviewed-by: Joel Granados 
Signed-off-by: Thomas Weißschuh 
Signed-off-by: Joel Granados

sysctl: Add size to register_net_sysctl function

2023-08-15T22:26:17+00:00

This commit adds size to the register_net_sysctl indirection function to
facilitate the removal of the sentinel elements (last empty markers)
from the ctl_table arrays. Though we don't actually remove any sentinels
in this commit, register_net_sysctl* now has the capability of
forwarding table_size for when that happens.

We create a new function register_net_sysctl_sz with an extra size
argument. A macro replaces the existing register_net_sysctl. The size in
the macro is SIZE_MAX instead of ARRAY_SIZE to avoid compilation errors
while we systematically migrate to register_net_sysctl_sz. Will change
to ARRAY_SIZE in subsequent commits.

Care is taken to add table_size to the stopping criteria in such a way
that when we remove the empty sentinel element, it will continue
stopping in the last element of the ctl_table array.

Signed-off-by: Joel Granados 
Suggested-by: Greg Kroah-Hartman 
Signed-off-by: Luis Chamberlain

sysctl: Add size to register_sysctl

2023-08-15T22:26:17+00:00

This commit adds table_size to register_sysctl in preparation for the
removal of the sentinel elements in the ctl_table arrays (last empty
markers). And though we do *not* remove any sentinels in this commit, we
set things up by either passing the table_size explicitly or using
ARRAY_SIZE on the ctl_table arrays.

We replace the register_syctl function with a macro that will add the
ARRAY_SIZE to the new register_sysctl_sz function. In this way the
callers that are already using an array of ctl_table structs do not
change. For the callers that pass a ctl_table array pointer, we pass the
table_size to register_sysctl_sz instead of the macro.

Signed-off-by: Joel Granados 
Suggested-by: Greg Kroah-Hartman 
Signed-off-by: Luis Chamberlain

sysctl: Add a size arg to __register_sysctl_table

2023-08-15T22:26:17+00:00

We make these changes in order to prepare __register_sysctl_table and
its callers for when we remove the sentinel element (empty element at
the end of ctl_table arrays). We don't actually remove any sentinels in
this commit, but we *do* make sure to use ARRAY_SIZE so the table_size
is available when the removal occurs.

We add a table_size argument to __register_sysctl_table and adjust
callers, all of which pass ctl_table pointers and need an explicit call
to ARRAY_SIZE. We implement a size calculation in register_net_sysctl in
order to forward the size of the array pointer received from the network
register calls.

The new table_size argument does not yet have any effect in the
init_header call which is still dependent on the sentinel's presence.
table_size *does* however drive the `kzalloc` allocation in
__register_sysctl_table with no adverse effects as the allocated memory
is either one element greater than the calculated ctl_table array (for
the calls in ipc_sysctl.c, mq_sysctl.c and ucount.c) or the exact size
of the calculated ctl_table array (for the call from sysctl_net.c and
register_sysctl). This approach will allows us to "just" remove the
sentinel without further changes to __register_sysctl_table as
table_size will represent the exact size for all the callers at that
point.

Signed-off-by: Joel Granados 
Signed-off-by: Luis Chamberlain

sections: move and rename core_kernel_data() to is_kernel_core_data()

2021-11-09T18:02:50+00:00

Move core_kernel_data() into sections.h and rename it to
is_kernel_core_data(), also make it return bool value, then update all the
callers.

Link: https://lkml.kernel.org/r/20210930071143.63410-4-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang 
Reviewed-by: Sergey Senozhatsky 
Cc: Arnd Bergmann 
Cc: Steven Rostedt 
Cc: Ingo Molnar 
Cc: "David S. Miller" 
Cc: Alexander Potapenko 
Cc: Alexei Starovoitov 
Cc: Andrey Konovalov 
Cc: Andrey Ryabinin 
Cc: Benjamin Herrenschmidt 
Cc: Borislav Petkov 
Cc: Christophe Leroy 
Cc: Dmitry Vyukov 
Cc: Ivan Kokshaysky 
Cc: Matt Turner 
Cc: Michael Ellerman 
Cc: Michal Simek 
Cc: Paul Mackerras 
Cc: Petr Mladek 
Cc: Richard Henderson 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

net: Ensure net namespace isolation of sysctls

2021-04-12T20:27:11+00:00

This adds an ensure_safe_net_sysctl() check during register_net_sysctl()
to validate that sysctl table entries for a non-init_net netns are
sufficiently isolated. To be netns-safe, an entry must adhere to at
least (and usually exactly) one of these rules:

1. It is marked read-only inside the netns.
2. Its data pointer does not point to kernel/module global data.

An entry which fails both of these checks is indicative of a bug,
whereby a child netns can affect global net sysctl values.

If such an entry is found, this code will issue a warning to the kernel
log, and force the entry to be read-only to prevent a leak.

To test, simply create a new netns:

    $ sudo ip netns add dummy

As it sits now, this patch will WARN for two sysctls which will be
addressed in a subsequent patch:
- /proc/sys/net/netfilter/nf_conntrack_max
- /proc/sys/net/netfilter/nf_conntrack_expect_max

Signed-off-by: Jonathon Reinhart 
Signed-off-by: David S. Miller

treewide: Add SPDX license identifier for missed files

2019-05-21T08:50:45+00:00

Add SPDX license identifiers to all files which:

 - Have no license information of any form

 - Have EXPORT_.*_SYMBOL_GPL inside which was used in the
   initial scan/conversion to ignore the file

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

sysctl: Remove dead register_sysctl_root

2017-04-17T04:42:49+00:00

The function no longer does anything.  The is only a single caller of
register_sysctl_root when semantically there should be two.  Remove
this function so that if someone decides this functionality is needed
again it will be obvious all of the callers of setup_sysctl_set need
to be audited and modified appropriately.

Signed-off-by: "Eric W. Biederman"