kernel/exec_domain.c

   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/config.h>
  11 #include <linux/init.h>
  12 #include <linux/kernel.h>
  13 #include <linux/kmod.h>
  14 #include <linux/module.h>
  15 #include <linux/personality.h>
  16 #include <linux/sched.h>
  17 #include <linux/sysctl.h>
  18 #include <linux/types.h>
  19
  20
  21 static void default_handler(int, struct pt_regs *);
  22
  23 static struct exec_domain *exec_domains = &default_exec_domain;
  24 static rwlock_t exec_domains_lock = RW_LOCK_UNLOCKED;
  25
  26
  27 static u_long ident_map[32] = {
  28         0,      1,      2,      3,      4,      5,      6,      7,
  29         8,      9,      10,     11,     12,     13,     14,     15,
  30         16,     17,     18,     19,     20,     21,     22,     23,
  31         24,     25,     26,     27,     28,     29,     30,     31
  32 };
  33
  34 struct exec_domain default_exec_domain = {
  35         "Linux",                /* name */
  36         default_handler,        /* lcall7 causes a seg fault. */
  37         0, 0,                   /* PER_LINUX personality. */
  38         ident_map,              /* Identity map signals. */
  39         ident_map,              /*  - both ways. */
  40 };
  41
  42
  43 static void
  44 default_handler(int segment, struct pt_regs *regp)
  45 {
  46         u_long                  pers = 0;
  47
  48         /*
  49          * This may have been a static linked SVr4 binary, so we would
  50          * have the personality set incorrectly. Or it might have been
  51          * a Solaris/x86 binary. We can tell which because the former
  52          * uses lcall7, while the latter used lcall 0x27.
  53          * Try to find or load the appropriate personality, and fall back
  54          * to just forcing a SEGV.
  55          *
  56          * XXX: this is IA32-specific and should be moved to the MD-tree.
  57          */
  58         switch (segment) {
  59 #ifdef __i386__
  60         case 0x07:
  61                 pers = abi_defhandler_lcall7;
  62                 break;
  63         case 0x27:
  64                 pers = PER_SOLARIS;
  65                 break;
  66 #endif
  67         }
  68         set_personality(pers);
  69
  70         if (current_thread_info()->exec_domain->handler != default_handler)
  71                 current_thread_info()->exec_domain->handler(segment, regp);
  72         else
  73                 send_sig(SIGSEGV, current, 1);
  74 }
  75
  76 static struct exec_domain *
  77 lookup_exec_domain(u_long personality)
  78 {
  79         struct exec_domain *    ep;
  80         u_long                  pers = personality(personality);
  81
  82         read_lock(&exec_domains_lock);
  83         for (ep = exec_domains; ep; ep = ep->next) {
  84                 if (pers >= ep->pers_low && pers <= ep->pers_high)
  85                         if (try_inc_mod_count(ep->module))
  86                                 goto out;
  87         }
  88
  89 #ifdef CONFIG_KMOD
  90         read_unlock(&exec_domains_lock);
  91         {
  92                 char buffer[30];
  93                 sprintf(buffer, "personality-%ld", pers);
  94                 request_module(buffer);
  95         }
  96         read_lock(&exec_domains_lock);
  97
  98         for (ep = exec_domains; ep; ep = ep->next) {
  99                 if (pers >= ep->pers_low && pers <= ep->pers_high)
 100                         if (try_inc_mod_count(ep->module))
 101                                 goto out;
 102         }
 103 #endif
 104
 105         ep = &default_exec_domain;
 106 out:
 107         read_unlock(&exec_domains_lock);
 108         return (ep);
 109 }
 110
 111 int
 112 register_exec_domain(struct exec_domain *ep)
 113 {
 114         struct exec_domain      *tmp;
 115         int                     err = -EBUSY;
 116
 117         if (ep == NULL)
 118                 return -EINVAL;
 119
 120         if (ep->next != NULL)
 121                 return -EBUSY;
 122
 123         write_lock(&exec_domains_lock);
 124         for (tmp = exec_domains; tmp; tmp = tmp->next) {
 125                 if (tmp == ep)
 126                         goto out;
 127         }
 128
 129         ep->next = exec_domains;
 130         exec_domains = ep;
 131         err = 0;
 132
 133 out:
 134         write_unlock(&exec_domains_lock);
 135         return (err);
 136 }
 137
 138 int
 139 unregister_exec_domain(struct exec_domain *ep)
 140 {
 141         struct exec_domain      **epp;
 142
 143         epp = &exec_domains;
 144         write_lock(&exec_domains_lock);
 145         for (epp = &exec_domains; *epp; epp = &(*epp)->next) {
 146                 if (ep == *epp)
 147                         goto unregister;
 148         }
 149         write_unlock(&exec_domains_lock);
 150         return -EINVAL;
 151
 152 unregister:
 153         *epp = ep->next;
 154         ep->next = NULL;
 155         write_unlock(&exec_domains_lock);
 156         return 0;
 157 }
 158
 159 int
 160 __set_personality(u_long personality)
 161 {
 162         struct exec_domain      *ep, *oep;
 163
 164         ep = lookup_exec_domain(personality);
 165         if (ep == current_thread_info()->exec_domain) {
 166                 current->personality = personality;
 167                 return 0;
 168         }
 169
 170         if (atomic_read(&current->fs->count) != 1) {
 171                 struct fs_struct *fsp, *ofsp;
 172
 173                 fsp = copy_fs_struct(current->fs);
 174                 if (fsp == NULL) {
 175                         put_exec_domain(ep);
 176                         return -ENOMEM;;
 177                 }
 178
 179                 task_lock(current);
 180                 ofsp = current->fs;
 181                 current->fs = fsp;
 182                 task_unlock(current);
 183
 184                 put_fs_struct(ofsp);
 185         }
 186
 187         /*
 188          * At that point we are guaranteed to be the sole owner of
 189          * current->fs.
 190          */
 191
 192         current->personality = personality;
 193         oep = current_thread_info()->exec_domain;
 194         current_thread_info()->exec_domain = ep;
 195         set_fs_altroot();
 196
 197         put_exec_domain(oep);
 198
 199         printk(KERN_DEBUG "[%s:%d]: set personality to %lx\n",
 200                         current->comm, current->pid, personality);
 201         return 0;
 202 }
 203
 204 int
 205 get_exec_domain_list(char *page)
 206 {
 207         struct exec_domain      *ep;
 208         int                     len = 0;
 209
 210         read_lock(&exec_domains_lock);
 211         for (ep = exec_domains; ep && len < PAGE_SIZE - 80; ep = ep->next)
 212                 len += sprintf(page + len, "%d-%d\t%-16s\t[%s]\n",
 213                         ep->pers_low, ep->pers_high, ep->name,
 214                         ep->module ? ep->module->name : "kernel");
 215         read_unlock(&exec_domains_lock);
 216         return (len);
 217 }
 218
 219 asmlinkage long
 220 sys_personality(u_long personality)
 221 {
 222         u_long old = current->personality;;
 223
 224         if (personality != 0xffffffff) {
 225                 set_personality(personality);
 226                 if (current->personality != personality)
 227                         return -EINVAL;
 228         }
 229
 230         return (long)old;
 231 }
 232
 233
 234 EXPORT_SYMBOL(register_exec_domain);
 235 EXPORT_SYMBOL(unregister_exec_domain);
 236 EXPORT_SYMBOL(__set_personality);
 237
 238 /*
 239  * We have to have all sysctl handling for the Linux-ABI
 240  * in one place as the dynamic registration of sysctls is
 241  * horribly crufty in Linux <= 2.4.
 242  *
 243  * I hope the new sysctl schemes discussed for future versions
 244  * will obsolete this.
 245  *
 246  *                              --hch
 247  */
 248
 249 u_long abi_defhandler_coff = PER_SCOSVR3;
 250 u_long abi_defhandler_elf = PER_LINUX;
 251 u_long abi_defhandler_lcall7 = PER_SVR4;
 252 u_long abi_defhandler_libcso = PER_SVR4;
 253 u_int abi_traceflg;
 254 int abi_fake_utsname;
 255
 256 static struct ctl_table abi_table[] = {
 257         {ABI_DEFHANDLER_COFF, "defhandler_coff", &abi_defhandler_coff,
 258                 sizeof(int), 0644, NULL, &proc_doulongvec_minmax},
 259         {ABI_DEFHANDLER_ELF, "defhandler_elf", &abi_defhandler_elf,
 260                 sizeof(int), 0644, NULL, &proc_doulongvec_minmax},
 261         {ABI_DEFHANDLER_LCALL7, "defhandler_lcall7", &abi_defhandler_lcall7,
 262                 sizeof(int), 0644, NULL, &proc_doulongvec_minmax},
 263         {ABI_DEFHANDLER_LIBCSO, "defhandler_libcso", &abi_defhandler_libcso,
 264                 sizeof(int), 0644, NULL, &proc_doulongvec_minmax},
 265         {ABI_TRACE, "trace", &abi_traceflg,
 266                 sizeof(u_int), 0644, NULL, &proc_dointvec},
 267         {ABI_FAKE_UTSNAME, "fake_utsname", &abi_fake_utsname,
 268                 sizeof(int), 0644, NULL, &proc_dointvec},
 269         {0}
 270 };
 271
 272 static struct ctl_table abi_root_table[] = {
 273         {CTL_ABI, "abi", NULL, 0, 0555, abi_table},
 274         {0}
 275 };
 276
 277 static int __init
 278 abi_register_sysctl(void)
 279 {
 280         register_sysctl_table(abi_root_table, 1);
 281         return 0;
 282 }
 283
 284 __initcall(abi_register_sysctl);
 285
 286
 287 EXPORT_SYMBOL(abi_defhandler_coff);
 288 EXPORT_SYMBOL(abi_defhandler_elf);
 289 EXPORT_SYMBOL(abi_defhandler_lcall7);
 290 EXPORT_SYMBOL(abi_defhandler_libcso);
 291 EXPORT_SYMBOL(abi_traceflg);
 292 EXPORT_SYMBOL(abi_fake_utsname);