1 /* 2 * Handling of different ABIs (personalities). 3 * 4 * We group personalities into execution domains which have their 5 * own handlers for kernel entry points, signal mapping, etc... 6 * 7 * 2001-05-06 Complete rewrite, Christoph Hellwig (hch@infradead.org) 8 */ 9 10 #include <linux/init.h> 11 #include <linux/kernel.h> 12 #include <linux/kmod.h> 13 #include <linux/module.h> 14 #include <linux/personality.h> 15 #include <linux/proc_fs.h> 16 #include <linux/sched.h> 17 #include <linux/seq_file.h> 18 #include <linux/syscalls.h> 19 #include <linux/sysctl.h> 20 #include <linux/types.h> 21 #include <linux/fs_struct.h> 22 23 24 static void default_handler(int, struct pt_regs *); 25 26 static struct exec_domain *exec_domains = &default_exec_domain; 27 static DEFINE_RWLOCK(exec_domains_lock); 28 29 30 static unsigned long ident_map[32] = { 31 0, 1, 2, 3, 4, 5, 6, 7, 32 8, 9, 10, 11, 12, 13, 14, 15, 33 16, 17, 18, 19, 20, 21, 22, 23, 34 24, 25, 26, 27, 28, 29, 30, 31 35 }; 36 37 struct exec_domain default_exec_domain = { 38 .name = "Linux", /* name */ 39 .handler = default_handler, /* lcall7 causes a seg fault. */ 40 .pers_low = 0, /* PER_LINUX personality. */ 41 .pers_high = 0, /* PER_LINUX personality. */ 42 .signal_map = ident_map, /* Identity map signals. */ 43 .signal_invmap = ident_map, /* - both ways. */ 44 }; 45 46 47 static void 48 default_handler(int segment, struct pt_regs *regp) 49 { 50 set_personality(0); 51 52 if (current_thread_info()->exec_domain->handler != default_handler) 53 current_thread_info()->exec_domain->handler(segment, regp); 54 else 55 send_sig(SIGSEGV, current, 1); 56 } 57 58 static struct exec_domain * 59 lookup_exec_domain(unsigned int personality) 60 { 61 unsigned int pers = personality(personality); 62 struct exec_domain *ep; 63 64 read_lock(&exec_domains_lock); 65 for (ep = exec_domains; ep; ep = ep->next) { 66 if (pers >= ep->pers_low && pers <= ep->pers_high) 67 if (try_module_get(ep->module)) 68 goto out; 69 } 70 71 #ifdef CONFIG_MODULES 72 read_unlock(&exec_domains_lock); 73 request_module("personality-%d", pers); 74 read_lock(&exec_domains_lock); 75 76 for (ep = exec_domains; ep; ep = ep->next) { 77 if (pers >= ep->pers_low && pers <= ep->pers_high) 78 if (try_module_get(ep->module)) 79 goto out; 80 } 81 #endif 82 83 ep = &default_exec_domain; 84 out: 85 read_unlock(&exec_domains_lock); 86 return ep; 87 } 88 89 int 90 register_exec_domain(struct exec_domain *ep) 91 { 92 struct exec_domain *tmp; 93 int err = -EBUSY; 94 95 if (ep == NULL) 96 return -EINVAL; 97 98 if (ep->next != NULL) 99 return -EBUSY; 100 101 write_lock(&exec_domains_lock); 102 for (tmp = exec_domains; tmp; tmp = tmp->next) { 103 if (tmp == ep) 104 goto out; 105 } 106 107 ep->next = exec_domains; 108 exec_domains = ep; 109 err = 0; 110 111 out: 112 write_unlock(&exec_domains_lock); 113 return err; 114 } 115 EXPORT_SYMBOL(register_exec_domain); 116 117 int 118 unregister_exec_domain(struct exec_domain *ep) 119 { 120 struct exec_domain **epp; 121 122 epp = &exec_domains; 123 write_lock(&exec_domains_lock); 124 for (epp = &exec_domains; *epp; epp = &(*epp)->next) { 125 if (ep == *epp) 126 goto unregister; 127 } 128 write_unlock(&exec_domains_lock); 129 return -EINVAL; 130 131 unregister: 132 *epp = ep->next; 133 ep->next = NULL; 134 write_unlock(&exec_domains_lock); 135 return 0; 136 } 137 EXPORT_SYMBOL(unregister_exec_domain); 138 139 int __set_personality(unsigned int personality) 140 { 141 struct exec_domain *oep = current_thread_info()->exec_domain; 142 143 current_thread_info()->exec_domain = lookup_exec_domain(personality); 144 current->personality = personality; 145 module_put(oep->module); 146 147 return 0; 148 } 149 EXPORT_SYMBOL(__set_personality); 150 151 #ifdef CONFIG_PROC_FS 152 static int execdomains_proc_show(struct seq_file *m, void *v) 153 { 154 struct exec_domain *ep; 155 156 read_lock(&exec_domains_lock); 157 for (ep = exec_domains; ep; ep = ep->next) 158 seq_printf(m, "%d-%d\t%-16s\t[%s]\n", 159 ep->pers_low, ep->pers_high, ep->name, 160 module_name(ep->module)); 161 read_unlock(&exec_domains_lock); 162 return 0; 163 } 164 165 static int execdomains_proc_open(struct inode *inode, struct file *file) 166 { 167 return single_open(file, execdomains_proc_show, NULL); 168 } 169 170 static const struct file_operations execdomains_proc_fops = { 171 .open = execdomains_proc_open, 172 .read = seq_read, 173 .llseek = seq_lseek, 174 .release = single_release, 175 }; 176 177 static int __init proc_execdomains_init(void) 178 { 179 proc_create("execdomains", 0, NULL, &execdomains_proc_fops); 180 return 0; 181 } 182 module_init(proc_execdomains_init); 183 #endif 184 185 SYSCALL_DEFINE1(personality, unsigned int, personality) 186 { 187 unsigned int old = current->personality; 188 189 if (personality != 0xffffffff) 190 set_personality(personality); 191 192 return old; 193 } 194