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144 lines
3.2 KiB
144 lines
3.2 KiB
// 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 <[email protected]> |
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*/ |
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#include <linux/export.h> |
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#include <linux/uts.h> |
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#include <linux/utsname.h> |
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#include <linux/sysctl.h> |
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#include <linux/wait.h> |
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#include <linux/rwsem.h> |
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#ifdef CONFIG_PROC_SYSCTL |
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static void *get_uts(struct ctl_table *table) |
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{ |
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char *which = table->data; |
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struct uts_namespace *uts_ns; |
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uts_ns = current->nsproxy->uts_ns; |
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which = (which - (char *)&init_uts_ns) + (char *)uts_ns; |
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return which; |
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} |
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/* |
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* Special case of dostring for the UTS structure. This has locks |
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* to observe. Should this be in kernel/sys.c ???? |
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*/ |
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static int proc_do_uts_string(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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struct ctl_table uts_table; |
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int r; |
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char tmp_data[__NEW_UTS_LEN + 1]; |
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memcpy(&uts_table, table, sizeof(uts_table)); |
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uts_table.data = tmp_data; |
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/* |
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* Buffer the value in tmp_data so that proc_dostring() can be called |
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* without holding any locks. |
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* We also need to read the original value in the write==1 case to |
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* support partial writes. |
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*/ |
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down_read(&uts_sem); |
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memcpy(tmp_data, get_uts(table), sizeof(tmp_data)); |
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up_read(&uts_sem); |
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r = proc_dostring(&uts_table, write, buffer, lenp, ppos); |
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if (write) { |
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/* |
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* Write back the new value. |
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* Note that, since we dropped uts_sem, the result can |
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* theoretically be incorrect if there are two parallel writes |
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* at non-zero offsets to the same sysctl. |
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*/ |
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down_write(&uts_sem); |
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memcpy(get_uts(table), tmp_data, sizeof(tmp_data)); |
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up_write(&uts_sem); |
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proc_sys_poll_notify(table->poll); |
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} |
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return r; |
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} |
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#else |
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#define proc_do_uts_string NULL |
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#endif |
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static DEFINE_CTL_TABLE_POLL(hostname_poll); |
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static DEFINE_CTL_TABLE_POLL(domainname_poll); |
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static struct ctl_table uts_kern_table[] = { |
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{ |
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.procname = "ostype", |
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.data = init_uts_ns.name.sysname, |
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.maxlen = sizeof(init_uts_ns.name.sysname), |
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.mode = 0444, |
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.proc_handler = proc_do_uts_string, |
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}, |
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{ |
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.procname = "osrelease", |
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.data = init_uts_ns.name.release, |
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.maxlen = sizeof(init_uts_ns.name.release), |
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.mode = 0444, |
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.proc_handler = proc_do_uts_string, |
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}, |
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{ |
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.procname = "version", |
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.data = init_uts_ns.name.version, |
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.maxlen = sizeof(init_uts_ns.name.version), |
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.mode = 0444, |
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.proc_handler = proc_do_uts_string, |
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}, |
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{ |
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.procname = "hostname", |
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.data = init_uts_ns.name.nodename, |
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.maxlen = sizeof(init_uts_ns.name.nodename), |
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.mode = 0644, |
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.proc_handler = proc_do_uts_string, |
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.poll = &hostname_poll, |
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}, |
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{ |
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.procname = "domainname", |
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.data = init_uts_ns.name.domainname, |
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.maxlen = sizeof(init_uts_ns.name.domainname), |
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.mode = 0644, |
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.proc_handler = proc_do_uts_string, |
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.poll = &domainname_poll, |
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}, |
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{} |
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}; |
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static struct ctl_table uts_root_table[] = { |
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{ |
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.procname = "kernel", |
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.mode = 0555, |
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.child = uts_kern_table, |
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}, |
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{} |
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}; |
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#ifdef CONFIG_PROC_SYSCTL |
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/* |
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* Notify userspace about a change in a certain entry of uts_kern_table, |
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* identified by the parameter proc. |
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*/ |
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void uts_proc_notify(enum uts_proc proc) |
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{ |
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struct ctl_table *table = &uts_kern_table[proc]; |
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proc_sys_poll_notify(table->poll); |
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} |
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#endif |
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static int __init utsname_sysctl_init(void) |
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{ |
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register_sysctl_table(uts_root_table); |
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return 0; |
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} |
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device_initcall(utsname_sysctl_init);
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