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![Matteo Croce](/assets/img/avatar_default.png)
In the sysctl code the proc_dointvec_minmax() function is often used to validate the user supplied value between an allowed range. This function uses the extra1 and extra2 members from struct ctl_table as minimum and maximum allowed value. On sysctl handler declaration, in every source file there are some readonly variables containing just an integer which address is assigned to the extra1 and extra2 members, so the sysctl range is enforced. The special values 0, 1 and INT_MAX are very often used as range boundary, leading duplication of variables like zero=0, one=1, int_max=INT_MAX in different source files: $ git grep -E '\.extra[12].*&(zero|one|int_max)' |wc -l 248 Add a const int array containing the most commonly used values, some macros to refer more easily to the correct array member, and use them instead of creating a local one for every object file. This is the bloat-o-meter output comparing the old and new binary compiled with the default Fedora config: # scripts/bloat-o-meter -d vmlinux.o.old vmlinux.o add/remove: 2/2 grow/shrink: 0/2 up/down: 24/-188 (-164) Data old new delta sysctl_vals - 12 +12 __kstrtab_sysctl_vals - 12 +12 max 14 10 -4 int_max 16 - -16 one 68 - -68 zero 128 28 -100 Total: Before=20583249, After=20583085, chg -0.00% [mcroce@redhat.com: tipc: remove two unused variables] Link: http://lkml.kernel.org/r/20190530091952.4108-1-mcroce@redhat.com [akpm@linux-foundation.org: fix net/ipv6/sysctl_net_ipv6.c] [arnd@arndb.de: proc/sysctl: make firmware loader table conditional] Link: http://lkml.kernel.org/r/20190617130014.1713870-1-arnd@arndb.de [akpm@linux-foundation.org: fix fs/eventpoll.c] Link: http://lkml.kernel.org/r/20190430180111.10688-1-mcroce@redhat.com Signed-off-by: Matteo Croce <mcroce@redhat.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Kees Cook <keescook@chromium.org> Reviewed-by: Aaron Tomlin <atomlin@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
253 lines
6.1 KiB
C
253 lines
6.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2007
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*
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* Author: Eric Biederman <ebiederm@xmision.com>
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*/
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#include <linux/module.h>
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#include <linux/ipc.h>
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#include <linux/nsproxy.h>
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#include <linux/sysctl.h>
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#include <linux/uaccess.h>
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#include <linux/ipc_namespace.h>
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#include <linux/msg.h>
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#include "util.h"
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static void *get_ipc(struct ctl_table *table)
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{
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char *which = table->data;
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struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
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which = (which - (char *)&init_ipc_ns) + (char *)ipc_ns;
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return which;
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}
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#ifdef CONFIG_PROC_SYSCTL
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static int proc_ipc_dointvec(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp, loff_t *ppos)
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{
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struct ctl_table ipc_table;
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memcpy(&ipc_table, table, sizeof(ipc_table));
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ipc_table.data = get_ipc(table);
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return proc_dointvec(&ipc_table, write, buffer, lenp, ppos);
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}
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static int proc_ipc_dointvec_minmax(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp, loff_t *ppos)
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{
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struct ctl_table ipc_table;
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memcpy(&ipc_table, table, sizeof(ipc_table));
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ipc_table.data = get_ipc(table);
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return proc_dointvec_minmax(&ipc_table, write, buffer, lenp, ppos);
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}
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static int proc_ipc_dointvec_minmax_orphans(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp, loff_t *ppos)
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{
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struct ipc_namespace *ns = current->nsproxy->ipc_ns;
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int err = proc_ipc_dointvec_minmax(table, write, buffer, lenp, ppos);
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if (err < 0)
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return err;
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if (ns->shm_rmid_forced)
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shm_destroy_orphaned(ns);
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return err;
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}
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static int proc_ipc_doulongvec_minmax(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp, loff_t *ppos)
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{
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struct ctl_table ipc_table;
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memcpy(&ipc_table, table, sizeof(ipc_table));
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ipc_table.data = get_ipc(table);
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return proc_doulongvec_minmax(&ipc_table, write, buffer,
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lenp, ppos);
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}
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static int proc_ipc_auto_msgmni(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp, loff_t *ppos)
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{
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struct ctl_table ipc_table;
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int dummy = 0;
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memcpy(&ipc_table, table, sizeof(ipc_table));
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ipc_table.data = &dummy;
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if (write)
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pr_info_once("writing to auto_msgmni has no effect");
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return proc_dointvec_minmax(&ipc_table, write, buffer, lenp, ppos);
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}
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static int proc_ipc_sem_dointvec(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp, loff_t *ppos)
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{
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int ret, semmni;
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struct ipc_namespace *ns = current->nsproxy->ipc_ns;
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semmni = ns->sem_ctls[3];
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ret = proc_ipc_dointvec(table, write, buffer, lenp, ppos);
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if (!ret)
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ret = sem_check_semmni(current->nsproxy->ipc_ns);
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/*
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* Reset the semmni value if an error happens.
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*/
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if (ret)
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ns->sem_ctls[3] = semmni;
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return ret;
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}
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#else
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#define proc_ipc_doulongvec_minmax NULL
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#define proc_ipc_dointvec NULL
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#define proc_ipc_dointvec_minmax NULL
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#define proc_ipc_dointvec_minmax_orphans NULL
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#define proc_ipc_auto_msgmni NULL
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#define proc_ipc_sem_dointvec NULL
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#endif
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int ipc_mni = IPCMNI;
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int ipc_mni_shift = IPCMNI_SHIFT;
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int ipc_min_cycle = RADIX_TREE_MAP_SIZE;
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static struct ctl_table ipc_kern_table[] = {
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{
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.procname = "shmmax",
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.data = &init_ipc_ns.shm_ctlmax,
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.maxlen = sizeof(init_ipc_ns.shm_ctlmax),
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.mode = 0644,
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.proc_handler = proc_ipc_doulongvec_minmax,
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},
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{
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.procname = "shmall",
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.data = &init_ipc_ns.shm_ctlall,
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.maxlen = sizeof(init_ipc_ns.shm_ctlall),
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.mode = 0644,
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.proc_handler = proc_ipc_doulongvec_minmax,
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},
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{
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.procname = "shmmni",
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.data = &init_ipc_ns.shm_ctlmni,
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.maxlen = sizeof(init_ipc_ns.shm_ctlmni),
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.mode = 0644,
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.proc_handler = proc_ipc_dointvec_minmax,
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.extra1 = SYSCTL_ZERO,
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.extra2 = &ipc_mni,
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},
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{
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.procname = "shm_rmid_forced",
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.data = &init_ipc_ns.shm_rmid_forced,
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.maxlen = sizeof(init_ipc_ns.shm_rmid_forced),
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.mode = 0644,
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.proc_handler = proc_ipc_dointvec_minmax_orphans,
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.extra1 = SYSCTL_ZERO,
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.extra2 = SYSCTL_ONE,
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},
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{
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.procname = "msgmax",
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.data = &init_ipc_ns.msg_ctlmax,
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.maxlen = sizeof(init_ipc_ns.msg_ctlmax),
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.mode = 0644,
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.proc_handler = proc_ipc_dointvec_minmax,
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.extra1 = SYSCTL_ZERO,
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.extra2 = SYSCTL_INT_MAX,
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},
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{
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.procname = "msgmni",
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.data = &init_ipc_ns.msg_ctlmni,
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.maxlen = sizeof(init_ipc_ns.msg_ctlmni),
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.mode = 0644,
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.proc_handler = proc_ipc_dointvec_minmax,
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.extra1 = SYSCTL_ZERO,
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.extra2 = &ipc_mni,
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},
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{
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.procname = "auto_msgmni",
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.data = NULL,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_ipc_auto_msgmni,
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.extra1 = SYSCTL_ZERO,
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.extra2 = SYSCTL_ONE,
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},
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{
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.procname = "msgmnb",
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.data = &init_ipc_ns.msg_ctlmnb,
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.maxlen = sizeof(init_ipc_ns.msg_ctlmnb),
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.mode = 0644,
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.proc_handler = proc_ipc_dointvec_minmax,
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.extra1 = SYSCTL_ZERO,
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.extra2 = SYSCTL_INT_MAX,
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},
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{
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.procname = "sem",
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.data = &init_ipc_ns.sem_ctls,
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.maxlen = 4*sizeof(int),
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.mode = 0644,
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.proc_handler = proc_ipc_sem_dointvec,
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},
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#ifdef CONFIG_CHECKPOINT_RESTORE
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{
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.procname = "sem_next_id",
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.data = &init_ipc_ns.ids[IPC_SEM_IDS].next_id,
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.maxlen = sizeof(init_ipc_ns.ids[IPC_SEM_IDS].next_id),
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.mode = 0644,
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.proc_handler = proc_ipc_dointvec_minmax,
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.extra1 = SYSCTL_ZERO,
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.extra2 = SYSCTL_INT_MAX,
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},
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{
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.procname = "msg_next_id",
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.data = &init_ipc_ns.ids[IPC_MSG_IDS].next_id,
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.maxlen = sizeof(init_ipc_ns.ids[IPC_MSG_IDS].next_id),
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.mode = 0644,
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.proc_handler = proc_ipc_dointvec_minmax,
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.extra1 = SYSCTL_ZERO,
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.extra2 = SYSCTL_INT_MAX,
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},
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{
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.procname = "shm_next_id",
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.data = &init_ipc_ns.ids[IPC_SHM_IDS].next_id,
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.maxlen = sizeof(init_ipc_ns.ids[IPC_SHM_IDS].next_id),
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.mode = 0644,
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.proc_handler = proc_ipc_dointvec_minmax,
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.extra1 = SYSCTL_ZERO,
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.extra2 = SYSCTL_INT_MAX,
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},
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#endif
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{}
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};
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static struct ctl_table ipc_root_table[] = {
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{
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.procname = "kernel",
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.mode = 0555,
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.child = ipc_kern_table,
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},
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{}
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};
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static int __init ipc_sysctl_init(void)
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{
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register_sysctl_table(ipc_root_table);
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return 0;
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}
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device_initcall(ipc_sysctl_init);
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static int __init ipc_mni_extend(char *str)
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{
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ipc_mni = IPCMNI_EXTEND;
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ipc_mni_shift = IPCMNI_EXTEND_SHIFT;
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ipc_min_cycle = IPCMNI_EXTEND_MIN_CYCLE;
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pr_info("IPCMNI extended to %d.\n", ipc_mni);
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return 0;
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}
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early_param("ipcmni_extend", ipc_mni_extend);
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