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
default_handler(int segment,struct pt_regs * regp)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->exec_domain->handler != default_handler)
71 current->exec_domain->handler(segment, regp);
72 else
73 send_sig(SIGSEGV, current, 1);
74 }
75
76 static struct exec_domain *
lookup_exec_domain(u_long personality)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
register_exec_domain(struct exec_domain * ep)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
unregister_exec_domain(struct exec_domain * ep)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
__set_personality(u_long personality)160 __set_personality(u_long personality)
161 {
162 struct exec_domain *ep, *oep;
163
164 ep = lookup_exec_domain(personality);
165 if (ep == current->exec_domain) {
166 current->personality = personality;
167 return 0;
168 }
169
170 if (atomic_read(¤t->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->exec_domain;
194 current->exec_domain = ep;
195 set_fs_altroot();
196
197 put_exec_domain(oep);
198
199 return 0;
200 }
201
202 int
get_exec_domain_list(char * page)203 get_exec_domain_list(char *page)
204 {
205 struct exec_domain *ep;
206 int len = 0;
207
208 read_lock(&exec_domains_lock);
209 for (ep = exec_domains; ep && len < PAGE_SIZE - 80; ep = ep->next)
210 len += sprintf(page + len, "%d-%d\t%-16s\t[%s]\n",
211 ep->pers_low, ep->pers_high, ep->name,
212 ep->module ? ep->module->name : "kernel");
213 read_unlock(&exec_domains_lock);
214 return (len);
215 }
216
217 asmlinkage long
sys_personality(u_long personality)218 sys_personality(u_long personality)
219 {
220 u_long old = current->personality;;
221
222 if (personality != 0xffffffff) {
223 set_personality(personality);
224 if (current->personality != personality)
225 return -EINVAL;
226 }
227
228 return (long)old;
229 }
230
231
232 EXPORT_SYMBOL(register_exec_domain);
233 EXPORT_SYMBOL(unregister_exec_domain);
234 EXPORT_SYMBOL(__set_personality);
235
236 /*
237 * We have to have all sysctl handling for the Linux-ABI
238 * in one place as the dynamic registration of sysctls is
239 * horribly crufty in Linux <= 2.4.
240 *
241 * I hope the new sysctl schemes discussed for future versions
242 * will obsolete this.
243 *
244 * --hch
245 */
246
247 u_long abi_defhandler_coff = PER_SCOSVR3;
248 u_long abi_defhandler_elf = PER_LINUX;
249 u_long abi_defhandler_lcall7 = PER_SVR4;
250 u_long abi_defhandler_libcso = PER_SVR4;
251 u_int abi_traceflg;
252 int abi_fake_utsname;
253
254 static struct ctl_table abi_table[] = {
255 {ABI_DEFHANDLER_COFF, "defhandler_coff", &abi_defhandler_coff,
256 sizeof(int), 0644, NULL, &proc_doulongvec_minmax},
257 {ABI_DEFHANDLER_ELF, "defhandler_elf", &abi_defhandler_elf,
258 sizeof(int), 0644, NULL, &proc_doulongvec_minmax},
259 {ABI_DEFHANDLER_LCALL7, "defhandler_lcall7", &abi_defhandler_lcall7,
260 sizeof(int), 0644, NULL, &proc_doulongvec_minmax},
261 {ABI_DEFHANDLER_LIBCSO, "defhandler_libcso", &abi_defhandler_libcso,
262 sizeof(int), 0644, NULL, &proc_doulongvec_minmax},
263 {ABI_TRACE, "trace", &abi_traceflg,
264 sizeof(u_int), 0644, NULL, &proc_dointvec},
265 {ABI_FAKE_UTSNAME, "fake_utsname", &abi_fake_utsname,
266 sizeof(int), 0644, NULL, &proc_dointvec},
267 {0}
268 };
269
270 static struct ctl_table abi_root_table[] = {
271 {CTL_ABI, "abi", NULL, 0, 0555, abi_table},
272 {0}
273 };
274
275 static int __init
abi_register_sysctl(void)276 abi_register_sysctl(void)
277 {
278 register_sysctl_table(abi_root_table, 1);
279 return 0;
280 }
281
282 __initcall(abi_register_sysctl);
283
284
285 EXPORT_SYMBOL(abi_defhandler_coff);
286 EXPORT_SYMBOL(abi_defhandler_elf);
287 EXPORT_SYMBOL(abi_defhandler_lcall7);
288 EXPORT_SYMBOL(abi_defhandler_libcso);
289 EXPORT_SYMBOL(abi_traceflg);
290 EXPORT_SYMBOL(abi_fake_utsname);
291