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 #ifdef CONFIG_PROC_SYSCTL 19 20 static void *get_uts(struct ctl_table *table, int write) 21 { 22 char *which = table->data; 23 struct uts_namespace *uts_ns; 24 25 uts_ns = current->nsproxy->uts_ns; 26 which = (which - (char *)&init_uts_ns) + (char *)uts_ns; 27 28 if (!write) 29 down_read(&uts_sem); 30 else 31 down_write(&uts_sem); 32 return which; 33 } 34 35 static void put_uts(struct ctl_table *table, int write, void *which) 36 { 37 if (!write) 38 up_read(&uts_sem); 39 else 40 up_write(&uts_sem); 41 } 42 43 /* 44 * Special case of dostring for the UTS structure. This has locks 45 * to observe. Should this be in kernel/sys.c ???? 46 */ 47 static int proc_do_uts_string(struct ctl_table *table, int write, 48 void __user *buffer, size_t *lenp, loff_t *ppos) 49 { 50 struct ctl_table uts_table; 51 int r; 52 memcpy(&uts_table, table, sizeof(uts_table)); 53 uts_table.data = get_uts(table, write); 54 r = proc_dostring(&uts_table, write, buffer, lenp, ppos); 55 put_uts(table, write, uts_table.data); 56 57 if (write) 58 proc_sys_poll_notify(table->poll); 59 60 return r; 61 } 62 #else 63 #define proc_do_uts_string NULL 64 #endif 65 66 static DEFINE_CTL_TABLE_POLL(hostname_poll); 67 static DEFINE_CTL_TABLE_POLL(domainname_poll); 68 69 static struct ctl_table uts_kern_table[] = { 70 { 71 .procname = "ostype", 72 .data = init_uts_ns.name.sysname, 73 .maxlen = sizeof(init_uts_ns.name.sysname), 74 .mode = 0444, 75 .proc_handler = proc_do_uts_string, 76 }, 77 { 78 .procname = "osrelease", 79 .data = init_uts_ns.name.release, 80 .maxlen = sizeof(init_uts_ns.name.release), 81 .mode = 0444, 82 .proc_handler = proc_do_uts_string, 83 }, 84 { 85 .procname = "version", 86 .data = init_uts_ns.name.version, 87 .maxlen = sizeof(init_uts_ns.name.version), 88 .mode = 0444, 89 .proc_handler = proc_do_uts_string, 90 }, 91 { 92 .procname = "hostname", 93 .data = init_uts_ns.name.nodename, 94 .maxlen = sizeof(init_uts_ns.name.nodename), 95 .mode = 0644, 96 .proc_handler = proc_do_uts_string, 97 .poll = &hostname_poll, 98 }, 99 { 100 .procname = "domainname", 101 .data = init_uts_ns.name.domainname, 102 .maxlen = sizeof(init_uts_ns.name.domainname), 103 .mode = 0644, 104 .proc_handler = proc_do_uts_string, 105 .poll = &domainname_poll, 106 }, 107 {} 108 }; 109 110 static struct ctl_table uts_root_table[] = { 111 { 112 .procname = "kernel", 113 .mode = 0555, 114 .child = uts_kern_table, 115 }, 116 {} 117 }; 118 119 #ifdef CONFIG_PROC_SYSCTL 120 /* 121 * Notify userspace about a change in a certain entry of uts_kern_table, 122 * identified by the parameter proc. 123 */ 124 void uts_proc_notify(enum uts_proc proc) 125 { 126 struct ctl_table *table = &uts_kern_table[proc]; 127 128 proc_sys_poll_notify(table->poll); 129 } 130 #endif 131 132 static int __init utsname_sysctl_init(void) 133 { 134 register_sysctl_table(uts_root_table); 135 return 0; 136 } 137 138 device_initcall(utsname_sysctl_init); 139