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53 lines
1.3 KiB
53 lines
1.3 KiB
// SPDX-License-Identifier: GPL-2.0 |
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#include <linux/init.h> |
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#include <linux/mm.h> |
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#include <linux/security.h> |
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#include <linux/sysctl.h> |
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/* amount of vm to protect from userspace access by both DAC and the LSM*/ |
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unsigned long mmap_min_addr; |
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/* amount of vm to protect from userspace using CAP_SYS_RAWIO (DAC) */ |
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unsigned long dac_mmap_min_addr = CONFIG_DEFAULT_MMAP_MIN_ADDR; |
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/* amount of vm to protect from userspace using the LSM = CONFIG_LSM_MMAP_MIN_ADDR */ |
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/* |
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* Update mmap_min_addr = max(dac_mmap_min_addr, CONFIG_LSM_MMAP_MIN_ADDR) |
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*/ |
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static void update_mmap_min_addr(void) |
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{ |
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#ifdef CONFIG_LSM_MMAP_MIN_ADDR |
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if (dac_mmap_min_addr > CONFIG_LSM_MMAP_MIN_ADDR) |
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mmap_min_addr = dac_mmap_min_addr; |
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else |
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mmap_min_addr = CONFIG_LSM_MMAP_MIN_ADDR; |
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#else |
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mmap_min_addr = dac_mmap_min_addr; |
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#endif |
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} |
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/* |
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* sysctl handler which just sets dac_mmap_min_addr = the new value and then |
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* calls update_mmap_min_addr() so non MAP_FIXED hints get rounded properly |
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*/ |
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int mmap_min_addr_handler(struct ctl_table *table, int write, |
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void *buffer, size_t *lenp, loff_t *ppos) |
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{ |
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int ret; |
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if (write && !capable(CAP_SYS_RAWIO)) |
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return -EPERM; |
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ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos); |
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update_mmap_min_addr(); |
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return ret; |
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} |
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static int __init init_mmap_min_addr(void) |
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{ |
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update_mmap_min_addr(); |
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return 0; |
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} |
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pure_initcall(init_mmap_min_addr);
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