Cregit: Linux 6.3: min

Contributors: 13
Author	Tokens	Token Proportion	Commits	Commit Proportion
Eric Paris	77	53.10%	1	5.00%
Linus Torvalds (pre-git)	25	17.24%	6	30.00%
Kees Cook	14	9.66%	2	10.00%
David Howells	5	3.45%	1	5.00%
Linus Torvalds	5	3.45%	1	5.00%
Hideaki Yoshifuji / 吉藤英明	4	2.76%	1	5.00%
Greg Kroah-Hartman	4	2.76%	2	10.00%
Christoph Lameter	3	2.07%	1	5.00%
Paul Mundt	3	2.07%	1	5.00%
Mimi Zohar	2	1.38%	1	5.00%
H Hartley Sweeten	1	0.69%	1	5.00%
Eric W. Biedermann	1	0.69%	1	5.00%
Nicholas Piggin	1	0.69%	1	5.00%
Total	145		20

// SPDX-License-Identifier: GPL-2.0
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/security.h>
#include <linux/sysctl.h>

/* amount of vm to protect from userspace access by both DAC and the LSM*/
unsigned long mmap_min_addr;
/* amount of vm to protect from userspace using CAP_SYS_RAWIO (DAC) */
unsigned long dac_mmap_min_addr = CONFIG_DEFAULT_MMAP_MIN_ADDR;
/* amount of vm to protect from userspace using the LSM = CONFIG_LSM_MMAP_MIN_ADDR */

/*
 * Update mmap_min_addr = max(dac_mmap_min_addr, CONFIG_LSM_MMAP_MIN_ADDR)
 */
static void update_mmap_min_addr(void)
{
#ifdef CONFIG_LSM_MMAP_MIN_ADDR
	if (dac_mmap_min_addr > CONFIG_LSM_MMAP_MIN_ADDR)
		mmap_min_addr = dac_mmap_min_addr;
	else
		mmap_min_addr = CONFIG_LSM_MMAP_MIN_ADDR;
#else
	mmap_min_addr = dac_mmap_min_addr;
#endif
}

/*
 * sysctl handler which just sets dac_mmap_min_addr = the new value and then
 * calls update_mmap_min_addr() so non MAP_FIXED hints get rounded properly
 */
int mmap_min_addr_handler(struct ctl_table *table, int write,
			  void *buffer, size_t *lenp, loff_t *ppos)
{
	int ret;

	if (write && !capable(CAP_SYS_RAWIO))
		return -EPERM;

	ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);

	update_mmap_min_addr();

	return ret;
}

static int __init init_mmap_min_addr(void)
{
	update_mmap_min_addr();

	return 0;
}
pure_initcall(init_mmap_min_addr);

min_addr.c