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788084aba2
Currently SELinux enforcement of controls on the ability to map low memory is determined by the mmap_min_addr tunable. This patch causes SELinux to ignore the tunable and instead use a seperate Kconfig option specific to how much space the LSM should protect. The tunable will now only control the need for CAP_SYS_RAWIO and SELinux permissions will always protect the amount of low memory designated by CONFIG_LSM_MMAP_MIN_ADDR. This allows users who need to disable the mmap_min_addr controls (usual reason being they run WINE as a non-root user) to do so and still have SELinux controls preventing confined domains (like a web server) from being able to map some area of low memory. Signed-off-by: Eric Paris <eparis@redhat.com> Signed-off-by: James Morris <jmorris@namei.org>
50 lines
1.3 KiB
C
50 lines
1.3 KiB
C
#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, struct file *filp,
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void __user *buffer, size_t *lenp, loff_t *ppos)
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{
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int ret;
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ret = proc_doulongvec_minmax(table, write, filp, 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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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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