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bdde21d3e7
While reworking the LSM initialization code the
/proc/sys/vm/mmap_min_addr handler was inadvertently caught up in the
change and the procfs entry wasn't setup when CONFIG_SECURITY was not
selected at kernel build time. This patch restores the previous behavior
and ensures that the procfs entry is setup regardless of the
CONFIG_SECURITY state.
Future work will improve upon this, likely by moving the procfs handler
into the mm subsystem, but this patch should resolve the immediate
regression.
Fixes: 4ab5efcc28 ("lsm: consolidate all of the LSM framework initcalls")
Reported-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Tested-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Paul Moore <paul@paul-moore.com>
63 lines
1.6 KiB
C
63 lines
1.6 KiB
C
// 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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#include <linux/minmax.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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mmap_min_addr = umax(dac_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(const 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 const struct ctl_table min_addr_sysctl_table[] = {
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{
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.procname = "mmap_min_addr",
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.data = &dac_mmap_min_addr,
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.maxlen = sizeof(unsigned long),
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.mode = 0644,
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.proc_handler = mmap_min_addr_handler,
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},
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};
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static int __init mmap_min_addr_init(void)
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{
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register_sysctl_init("vm", min_addr_sysctl_table);
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update_mmap_min_addr();
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return 0;
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}
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pure_initcall(mmap_min_addr_init);
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