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| 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 | |
| 116 | int |
| 117 | unregister_exec_domain(struct exec_domain *ep) |
| 118 | { |
| 119 | struct exec_domain **epp; |
| 120 | |
| 121 | epp = &exec_domains; |
| 122 | write_lock(&exec_domains_lock); |
| 123 | for (epp = &exec_domains; *epp; epp = &(*epp)->next) { |
| 124 | if (ep == *epp) |
| 125 | goto unregister; |
| 126 | } |
| 127 | write_unlock(&exec_domains_lock); |
| 128 | return -EINVAL; |
| 129 | |
| 130 | unregister: |
| 131 | *epp = ep->next; |
| 132 | ep->next = NULL; |
| 133 | write_unlock(&exec_domains_lock); |
| 134 | return 0; |
| 135 | } |
| 136 | |
| 137 | int __set_personality(unsigned int personality) |
| 138 | { |
| 139 | struct exec_domain *oep = current_thread_info()->exec_domain; |
| 140 | |
| 141 | current_thread_info()->exec_domain = lookup_exec_domain(personality); |
| 142 | current->personality = personality; |
| 143 | module_put(oep->module); |
| 144 | |
| 145 | return 0; |
| 146 | } |
| 147 | |
| 148 | #ifdef CONFIG_PROC_FS |
| 149 | static int execdomains_proc_show(struct seq_file *m, void *v) |
| 150 | { |
| 151 | struct exec_domain *ep; |
| 152 | |
| 153 | read_lock(&exec_domains_lock); |
| 154 | for (ep = exec_domains; ep; ep = ep->next) |
| 155 | seq_printf(m, "%d-%d\t%-16s\t[%s]\n", |
| 156 | ep->pers_low, ep->pers_high, ep->name, |
| 157 | module_name(ep->module)); |
| 158 | read_unlock(&exec_domains_lock); |
| 159 | return 0; |
| 160 | } |
| 161 | |
| 162 | static int execdomains_proc_open(struct inode *inode, struct file *file) |
| 163 | { |
| 164 | return single_open(file, execdomains_proc_show, NULL); |
| 165 | } |
| 166 | |
| 167 | static const struct file_operations execdomains_proc_fops = { |
| 168 | .open = execdomains_proc_open, |
| 169 | .read = seq_read, |
| 170 | .llseek = seq_lseek, |
| 171 | .release = single_release, |
| 172 | }; |
| 173 | |
| 174 | static int __init proc_execdomains_init(void) |
| 175 | { |
| 176 | proc_create("execdomains", 0, NULL, &execdomains_proc_fops); |
| 177 | return 0; |
| 178 | } |
| 179 | module_init(proc_execdomains_init); |
| 180 | #endif |
| 181 | |
| 182 | SYSCALL_DEFINE1(personality, unsigned int, personality) |
| 183 | { |
| 184 | unsigned int old = current->personality; |
| 185 | |
| 186 | if (personality != 0xffffffff) |
| 187 | set_personality(personality); |
| 188 | |
| 189 | return old; |
| 190 | } |
| 191 | |
| 192 | |
| 193 | EXPORT_SYMBOL(register_exec_domain); |
| 194 | EXPORT_SYMBOL(unregister_exec_domain); |
| 195 | EXPORT_SYMBOL(__set_personality); |
| 196 |
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