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 18 static void *get_uts(ctl_table *table, int write) 19 { 20 char *which = table->data; 21 struct uts_namespace *uts_ns; 22 23 uts_ns = current->nsproxy->uts_ns; 24 which = (which - (char *)&init_uts_ns) + (char *)uts_ns; 25 26 if (!write) 27 down_read(&uts_sem); 28 else 29 down_write(&uts_sem); 30 return which; 31 } 32 33 static void put_uts(ctl_table *table, int write, void *which) 34 { 35 if (!write) 36 up_read(&uts_sem); 37 else 38 up_write(&uts_sem); 39 } 40 41 #ifdef CONFIG_PROC_SYSCTL 42 /* 43 * Special case of dostring for the UTS structure. This has locks 44 * to observe. Should this be in kernel/sys.c ???? 45 */ 46 static int proc_do_uts_string(ctl_table *table, int write, 47 void __user *buffer, size_t *lenp, loff_t *ppos) 48 { 49 struct ctl_table uts_table; 50 int r; 51 memcpy(&uts_table, table, sizeof(uts_table)); 52 uts_table.data = get_uts(table, write); 53 r = proc_dostring(&uts_table,write,buffer,lenp, ppos); 54 put_uts(table, write, uts_table.data); 55 56 if (write) 57 proc_sys_poll_notify(table->poll); 58 59 return r; 60 } 61 #else 62 #define proc_do_uts_string NULL 63 #endif 64 65 static DEFINE_CTL_TABLE_POLL(hostname_poll); 66 static DEFINE_CTL_TABLE_POLL(domainname_poll); 67 68 static struct ctl_table uts_kern_table[] = { 69 { 70 .procname = "ostype", 71 .data = init_uts_ns.name.sysname, 72 .maxlen = sizeof(init_uts_ns.name.sysname), 73 .mode = 0444, 74 .proc_handler = proc_do_uts_string, 75 }, 76 { 77 .procname = "osrelease", 78 .data = init_uts_ns.name.release, 79 .maxlen = sizeof(init_uts_ns.name.release), 80 .mode = 0444, 81 .proc_handler = proc_do_uts_string, 82 }, 83 { 84 .procname = "version", 85 .data = init_uts_ns.name.version, 86 .maxlen = sizeof(init_uts_ns.name.version), 87 .mode = 0444, 88 .proc_handler = proc_do_uts_string, 89 }, 90 { 91 .procname = "hostname", 92 .data = init_uts_ns.name.nodename, 93 .maxlen = sizeof(init_uts_ns.name.nodename), 94 .mode = 0644, 95 .proc_handler = proc_do_uts_string, 96 .poll = &hostname_poll, 97 }, 98 { 99 .procname = "domainname", 100 .data = init_uts_ns.name.domainname, 101 .maxlen = sizeof(init_uts_ns.name.domainname), 102 .mode = 0644, 103 .proc_handler = proc_do_uts_string, 104 .poll = &domainname_poll, 105 }, 106 {} 107 }; 108 109 static struct ctl_table uts_root_table[] = { 110 { 111 .procname = "kernel", 112 .mode = 0555, 113 .child = uts_kern_table, 114 }, 115 {} 116 }; 117 118 #ifdef CONFIG_PROC_SYSCTL 119 /* 120 * Notify userspace about a change in a certain entry of uts_kern_table, 121 * identified by the parameter proc. 122 */ 123 void uts_proc_notify(enum uts_proc proc) 124 { 125 struct ctl_table *table = &uts_kern_table[proc]; 126 127 proc_sys_poll_notify(table->poll); 128 } 129 #endif 130 131 static int __init utsname_sysctl_init(void) 132 { 133 register_sysctl_table(uts_root_table); 134 return 0; 135 } 136 137 __initcall(utsname_sysctl_init); 138