1#include <linux/init.h> 2#include <linux/mm.h> 3#include <linux/security.h> 4#include <linux/sysctl.h> 5 6/* amount of vm to protect from userspace access by both DAC and the LSM*/ 7unsigned long mmap_min_addr; 8/* amount of vm to protect from userspace using CAP_SYS_RAWIO (DAC) */ 9unsigned long dac_mmap_min_addr = CONFIG_DEFAULT_MMAP_MIN_ADDR; 10/* amount of vm to protect from userspace using the LSM = CONFIG_LSM_MMAP_MIN_ADDR */ 11 12/* 13 * Update mmap_min_addr = max(dac_mmap_min_addr, CONFIG_LSM_MMAP_MIN_ADDR) 14 */ 15static void update_mmap_min_addr(void) 16{ 17#ifdef CONFIG_LSM_MMAP_MIN_ADDR 18 if (dac_mmap_min_addr > CONFIG_LSM_MMAP_MIN_ADDR) 19 mmap_min_addr = dac_mmap_min_addr; 20 else 21 mmap_min_addr = CONFIG_LSM_MMAP_MIN_ADDR; 22#else 23 mmap_min_addr = dac_mmap_min_addr; 24#endif 25} 26 27/* 28 * sysctl handler which just sets dac_mmap_min_addr = the new value and then 29 * calls update_mmap_min_addr() so non MAP_FIXED hints get rounded properly 30 */ 31int mmap_min_addr_handler(struct ctl_table *table, int write, 32 void __user *buffer, size_t *lenp, loff_t *ppos) 33{ 34 int ret; 35 36 if (write && !capable(CAP_SYS_RAWIO)) 37 return -EPERM; 38 39 ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos); 40 41 update_mmap_min_addr(); 42 43 return ret; 44} 45 46static int __init init_mmap_min_addr(void) 47{ 48 update_mmap_min_addr(); 49 50 return 0; 51} 52pure_initcall(init_mmap_min_addr); 53