[Patch] sysctl: make CONFIG_SYSCTL_SYSCALL default to n

From: WANG Cong
Date: Thu Aug 18 2011 - 01:36:06 EST


IIRC, when I tried to send a patch to remove it, Andi told me
we still need to keep compabitlies for old libc, so we can't
remove this completely. Then just make it default to n and
remove the doc from feature-removal-schedule.txt.

Signed-off-by: WANG Cong <amwang@xxxxxxxxxx>
Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>

---
diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index c4a6e14..ad5d67b 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -133,41 +133,6 @@ Who: Pavel Machek <pavel@xxxxxx>

---------------------------

-What: sys_sysctl
-When: September 2010
-Option: CONFIG_SYSCTL_SYSCALL
-Why: The same information is available in a more convenient from
- /proc/sys, and none of the sysctl variables appear to be
- important performance wise.
-
- Binary sysctls are a long standing source of subtle kernel
- bugs and security issues.
-
- When I looked several months ago all I could find after
- searching several distributions were 5 user space programs and
- glibc (which falls back to /proc/sys) using this syscall.
-
- The man page for sysctl(2) documents it as unusable for user
- space programs.
-
- sysctl(2) is not generally ABI compatible to a 32bit user
- space application on a 64bit and a 32bit kernel.
-
- For the last several months the policy has been no new binary
- sysctls and no one has put forward an argument to use them.
-
- Binary sysctls issues seem to keep happening appearing so
- properly deprecating them (with a warning to user space) and a
- 2 year grace warning period will mean eventually we can kill
- them and end the pain.
-
- In the mean time individual binary sysctls can be dealt with
- in a piecewise fashion.
-
-Who: Eric Biederman <ebiederm@xxxxxxxxxxxx>
-
----------------------------
-
What: /proc/<pid>/oom_adj
When: August 2012
Why: /proc/<pid>/oom_adj allows userspace to influence the oom killer's
diff --git a/init/Kconfig b/init/Kconfig
index d627783..566b2a4 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -935,7 +935,7 @@ config UID16
config SYSCTL_SYSCALL
bool "Sysctl syscall support" if EXPERT
depends on PROC_SYSCTL
- default y
+ default n
select SYSCTL
---help---
sys_sysctl uses binary paths that have been found challenging
@@ -947,7 +947,7 @@ config SYSCTL_SYSCALL
trying to save some space it is probably safe to disable this,
making your kernel marginally smaller.

- If unsure say Y here.
+ If unsure say N here.

config KALLSYMS
bool "Load all symbols for debugging/ksymoops" if EXPERT
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