As predicted during code review, the sysctl(2) changes made systems with
old glibc nearly unusable.  About every command gives a:

  warning: process `ls' used the deprecated sysctl system call with 1.4

warning in the log.

I see this on a SUSE 10.0 system with glibc 2.3.5.

Don't warn for this common case.
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

A malicious user could have passed in a ctl_name of 0 and triggered
the well know ctl_name to procname mapping code, instead of the wild
card matching code.  This is a slight problem as wild card entries don't
have procnames, and because in some alternate universe a network device
might have ifindex 0.  So test for and handle wild card entries first.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>

dev_get_by_index does not exist when the network stack is not
compiled in, so only include the code to follow wild card paths
when the network stack is present.

I have shuffled the code around a little to make it clear
that dev_put is called after dev_get_by_index showing that
there is no leak.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>

Now that the glibc pthread implemenation no longers uses sysctl() users
of sysctl are as rare as hen's teeth.  So remove the glibc exception
from the warning, and use the standard printk_ratelimit instead of
rolling our own.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>

To simply maintenance and to be able to remove all of the binary
sysctl support from various subsystems I have rewritten the binary
sysctl code as a compatibility wrapper around proc/sys.

The code is built around a hard coded table based on the table
in sysctl_check.c that lists all of our current binary sysctls
and provides enough information to convert from the sysctl
binary input into into ascii and back again.  New in this
patch is the realization that the only dynamic entries
that need to be handled have ifname as the asscii string
and ifindex as their ctl_name.

When a sys_sysctl is called the code now looks in the
translation table converting the binary name to the
path under /proc where the value is to be found.  Opens
that file, and calls into a format conversion wrapper
that calls fop->read and then fop->write as appropriate.

Since in practice the practically no one uses or tests
sys_sysctl rewritting the code to be beautiful is a little
silly.  The redeeming merit of this work is it allows us to
rip out all of the binary sysctl syscall support from
everywhere else in the tree.  Allowing us to remove
a lot of dead (after this patch) and barely maintained code.

In addition it becomes much easier to optimize the sysctl
implementation for being the backing store of /proc/sys,
without having to worry about sys_sysctl.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>

Now that all of the architectures use compat_sys_sysctl do_sysctl
can become static.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>

This uses compat_alloc_userspace to remove the various
hacks to allow do_sysctl to write to throuh oldlenp.

The rest of our mature compat syscall helper facitilies
are used as well to ensure we have a nice clean maintainable
compat syscall that can be used on all architectures.

The motiviation for a generic compat sysctl (besides the
obvious hack removal) is to reduce the number of compat
sysctl defintions out there so I can refactor the
binary sysctl implementation.

ppc already used the name compat_sys_sysctl so I remove the
ppcs version here.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>

Read in the binary sysctl path once, instead of reread it
from user space each time the code needs to access a path
element.

The deprecated sysctl warning is moved to do_sysctl so
that the compat_sysctl entries syscalls will also warn.

The return of -ENOSYS when !CONFIG_SYSCTL_SYSCALL is moved
to binary_sysctl.  Always leaving a do_sysctl available
that handles !CONFIG_SYSCTL_SYSCALL and printing the
deprecated sysctl warning allows for a single defitition
of the sysctl syscall.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>

In preparation for more invasive cleanups separate the core
binary sysctl logic into it's own file.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>