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Commit eec4844f authored by Matteo Croce's avatar Matteo Croce Committed by Linus Torvalds
Browse files

proc/sysctl: add shared variables for range check 

In the sysctl code the proc_dointvec_minmax() function is often used to
validate the user supplied value between an allowed range.  This
function uses the extra1 and extra2 members from struct ctl_table as
minimum and maximum allowed value.

On sysctl handler declaration, in every source file there are some
readonly variables containing just an integer which address is assigned
to the extra1 and extra2 members, so the sysctl range is enforced.

The special values 0, 1 and INT_MAX are very often used as range
boundary, leading duplication of variables like zero=0, one=1,
int_max=INT_MAX in different source files:

    $ git grep -E '\.extra[12].*&(zero|one|int_max)' |wc -l
    248

Add a const int array containing the most commonly used values, some
macros to refer more easily to the correct array member, and use them
instead of creating a local one for every object file.

This is the bloat-o-meter output comparing the old and new binary
compiled with the default Fedora config:

    # scripts/bloat-o-meter -d vmlinux.o.old vmlinux.o
    add/remove: 2/2 grow/shrink: 0/2 up/down: 24/-188 (-164)
    Data                                         old     new   delta
    sysctl_vals                                    -      12     +12
    __kstrtab_sysctl_vals                          -      12     +12
    max                                           14      10      -4
    int_max                                       16       -     -16
    one                                           68       -     -68
    zero                                         128      28    -100
    Total: Before=20583249, After=20583085, chg -0.00%

[mcroce@redhat.com: tipc: remove two unused variables]
  Link: http://lkml.kernel.org/r/20190530091952.4108-1-mcroce@redhat.com
[akpm@linux-foundation.org: fix net/ipv6/sysctl_net_ipv6.c]
[arnd@arndb.de: proc/sysctl: make firmware loader table conditional]
  Link: http://lkml.kernel.org/r/20190617130014.1713870-1-arnd@arndb.de
[akpm@linux-foundation.org: fix fs/eventpoll.c]
Link: http://lkml.kernel.org/r/20190430180111.10688-1-mcroce@redhat.com


Signed-off-by: default avatarMatteo Croce <mcroce@redhat.com>
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarAaron Tomlin <atomlin@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 37109694

arch/s390/appldata/appldata_base.c

+5 −10
Original line number Diff line number Diff line
@@ -220,15 +220,13 @@ appldata_timer_handler(struct ctl_table *ctl, int write, 
			   void __user *buffer, size_t *lenp, loff_t *ppos)

{

	int timer_active = appldata_timer_active;

	int zero = 0;

	int one = 1;

	int rc;

	struct ctl_table ctl_entry = {

		.procname	= ctl->procname,

		.data		= &timer_active,

		.maxlen		= sizeof(int),

		.extra1		= &zero,

		.extra2		= &one,

		.extra1		= SYSCTL_ZERO,

		.extra2		= SYSCTL_ONE,

	};



	rc = proc_douintvec_minmax(&ctl_entry, write, buffer, lenp, ppos);
@@ -255,13 +253,12 @@ appldata_interval_handler(struct ctl_table *ctl, int write, 
			   void __user *buffer, size_t *lenp, loff_t *ppos)

{

	int interval = appldata_interval;

	int one = 1;

	int rc;

	struct ctl_table ctl_entry = {

		.procname	= ctl->procname,

		.data		= &interval,

		.maxlen		= sizeof(int),

		.extra1		= &one,

		.extra1		= SYSCTL_ONE,

	};



	rc = proc_dointvec_minmax(&ctl_entry, write, buffer, lenp, ppos);
@@ -289,13 +286,11 @@ appldata_generic_handler(struct ctl_table *ctl, int write, 
	struct list_head *lh;

	int rc, found;

	int active;

	int zero = 0;

	int one = 1;

	struct ctl_table ctl_entry = {

		.data		= &active,

		.maxlen		= sizeof(int),

		.extra1		= &zero,

		.extra2		= &one,

		.extra1		= SYSCTL_ZERO,

		.extra2		= SYSCTL_ONE,

	};



	found = 0;

arch/s390/kernel/topology.c

+2 −4
Original line number Diff line number Diff line
@@ -587,15 +587,13 @@ static int topology_ctl_handler(struct ctl_table *ctl, int write, 
{

	int enabled = topology_is_enabled();

	int new_mode;

	int zero = 0;

	int one = 1;

	int rc;

	struct ctl_table ctl_entry = {

		.procname	= ctl->procname,

		.data		= &enabled,

		.maxlen		= sizeof(int),

		.extra1		= &zero,

		.extra2		= &one,

		.extra1		= SYSCTL_ZERO,

		.extra2		= SYSCTL_ONE,

	};



	rc = proc_douintvec_minmax(&ctl_entry, write, buffer, lenp, ppos);

arch/x86/entry/vdso/vdso32-setup.c

+2 −5
Original line number Diff line number Diff line
@@ -65,9 +65,6 @@ subsys_initcall(sysenter_setup); 
/* Register vsyscall32 into the ABI table */

#include <linux/sysctl.h>



static const int zero;

static const int one = 1;



static struct ctl_table abi_table2[] = {

	{

		.procname	= "vsyscall32",
@@ -75,8 +72,8 @@ static struct ctl_table abi_table2[] = { 
		.maxlen		= sizeof(int),

		.mode		= 0644,

		.proc_handler	= proc_dointvec_minmax,

		.extra1		= (int *)&zero,

		.extra2		= (int *)&one,

		.extra1		= SYSCTL_ZERO,

		.extra2		= SYSCTL_ONE,

	},

	{}

};

arch/x86/kernel/itmt.c

+2 −4
Original line number Diff line number Diff line
@@ -65,8 +65,6 @@ static int sched_itmt_update_handler(struct ctl_table *table, int write, 
	return ret;

}



static unsigned int zero;

static unsigned int one = 1;

static struct ctl_table itmt_kern_table[] = {

	{

		.procname	= "sched_itmt_enabled",
@@ -74,8 +72,8 @@ static struct ctl_table itmt_kern_table[] = { 
		.maxlen		= sizeof(unsigned int),

		.mode		= 0644,

		.proc_handler	= sched_itmt_update_handler,

		.extra1		= &zero,

		.extra2		= &one,

		.extra1		= SYSCTL_ZERO,

		.extra2		= SYSCTL_ONE,

	},

	{}

};

drivers/base/firmware_loader/fallback_table.c

+6 −7
Original line number Diff line number Diff line
@@ -16,9 +16,6 @@ 
 * firmware fallback configuration table

 */



static unsigned int zero;

static unsigned int one = 1;



struct firmware_fallback_config fw_fallback_config = {

	.force_sysfs_fallback = IS_ENABLED(CONFIG_FW_LOADER_USER_HELPER_FALLBACK),

	.loading_timeout = 60,
@@ -26,6 +23,7 @@ struct firmware_fallback_config fw_fallback_config = { 
};

EXPORT_SYMBOL_GPL(fw_fallback_config);



#ifdef CONFIG_SYSCTL

struct ctl_table firmware_config_table[] = {

	{

		.procname	= "force_sysfs_fallback",
@@ -33,8 +31,8 @@ struct ctl_table firmware_config_table[] = { 
		.maxlen         = sizeof(unsigned int),

		.mode           = 0644,

		.proc_handler   = proc_douintvec_minmax,

		.extra1		= &zero,

		.extra2		= &one,

		.extra1		= SYSCTL_ZERO,

		.extra2		= SYSCTL_ONE,

	},

	{

		.procname	= "ignore_sysfs_fallback",
@@ -42,9 +40,10 @@ struct ctl_table firmware_config_table[] = { 
		.maxlen         = sizeof(unsigned int),

		.mode           = 0644,

		.proc_handler   = proc_douintvec_minmax,

		.extra1		= &zero,

		.extra2		= &one,

		.extra1		= SYSCTL_ZERO,

		.extra2		= SYSCTL_ONE,

	},

	{ }

};

EXPORT_SYMBOL_GPL(firmware_config_table);

#endif