1 /* 2 * Copyright (C) 2007 3 * 4 * Author: Eric Biederman <ebiederm@xmision.com> 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License as 8 * published by the Free Software Foundation, version 2 of the 9 * License. 10 */ 11 12 #include <linux/export.h> 13 #include <linux/uts.h> 14 #include <linux/utsname.h> 15 #include <linux/sysctl.h> 16 #include <linux/wait.h> 17 #include <linux/rwsem.h> 18 19 #ifdef CONFIG_PROC_SYSCTL 20 21 static void *get_uts(struct ctl_table *table, int write) 22 { 23 char *which = table->data; 24 struct uts_namespace *uts_ns; 25 26 uts_ns = current->nsproxy->uts_ns; 27 which = (which - (char *)&init_uts_ns) + (char *)uts_ns; 28 29 if (!write) 30 down_read(&uts_sem); 31 else 32 down_write(&uts_sem); 33 return which; 34 } 35 36 static void put_uts(struct ctl_table *table, int write, void *which) 37 { 38 if (!write) 39 up_read(&uts_sem); 40 else 41 up_write(&uts_sem); 42 } 43 44 /* 45 * Special case of dostring for the UTS structure. This has locks 46 * to observe. Should this be in kernel/sys.c ???? 47 */ 48 static int proc_do_uts_string(struct ctl_table *table, int write, 49 void __user *buffer, size_t *lenp, loff_t *ppos) 50 { 51 struct ctl_table uts_table; 52 int r; 53 memcpy(&uts_table, table, sizeof(uts_table)); 54 uts_table.data = get_uts(table, write); 55 r = proc_dostring(&uts_table, write, buffer, lenp, ppos); 56 put_uts(table, write, uts_table.data); 57 58 if (write) 59 proc_sys_poll_notify(table->poll); 60 61 return r; 62 } 63 #else 64 #define proc_do_uts_string NULL 65 #endif 66 67 static DEFINE_CTL_TABLE_POLL(hostname_poll); 68 static DEFINE_CTL_TABLE_POLL(domainname_poll); 69 70 static struct ctl_table uts_kern_table[] = { 71 { 72 .procname = "ostype", 73 .data = init_uts_ns.name.sysname, 74 .maxlen = sizeof(init_uts_ns.name.sysname), 75 .mode = 0444, 76 .proc_handler = proc_do_uts_string, 77 }, 78 { 79 .procname = "osrelease", 80 .data = init_uts_ns.name.release, 81 .maxlen = sizeof(init_uts_ns.name.release), 82 .mode = 0444, 83 .proc_handler = proc_do_uts_string, 84 }, 85 { 86 .procname = "version", 87 .data = init_uts_ns.name.version, 88 .maxlen = sizeof(init_uts_ns.name.version), 89 .mode = 0444, 90 .proc_handler = proc_do_uts_string, 91 }, 92 { 93 .procname = "hostname", 94 .data = init_uts_ns.name.nodename, 95 .maxlen = sizeof(init_uts_ns.name.nodename), 96 .mode = 0644, 97 .proc_handler = proc_do_uts_string, 98 .poll = &hostname_poll, 99 }, 100 { 101 .procname = "domainname", 102 .data = init_uts_ns.name.domainname, 103 .maxlen = sizeof(init_uts_ns.name.domainname), 104 .mode = 0644, 105 .proc_handler = proc_do_uts_string, 106 .poll = &domainname_poll, 107 }, 108 {} 109 }; 110 111 static struct ctl_table uts_root_table[] = { 112 { 113 .procname = "kernel", 114 .mode = 0555, 115 .child = uts_kern_table, 116 }, 117 {} 118 }; 119 120 #ifdef CONFIG_PROC_SYSCTL 121 /* 122 * Notify userspace about a change in a certain entry of uts_kern_table, 123 * identified by the parameter proc. 124 */ 125 void uts_proc_notify(enum uts_proc proc) 126 { 127 struct ctl_table *table = &uts_kern_table[proc]; 128 129 proc_sys_poll_notify(table->poll); 130 } 131 #endif 132 133 static int __init utsname_sysctl_init(void) 134 { 135 register_sysctl_table(uts_root_table); 136 return 0; 137 } 138 139 device_initcall(utsname_sysctl_init); 140