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/syscalls.h>
18 #include <linux/sysctl.h>
19 #include <linux/types.h>
20
21
22 static void default_handler(int, struct pt_regs *);
23
24 static struct exec_domain *exec_domains = &default_exec_domain;
25 static DEFINE_RWLOCK(exec_domains_lock);
26
27
28 static u_long ident_map[32] = {
29 0, 1, 2, 3, 4, 5, 6, 7,
30 8, 9, 10, 11, 12, 13, 14, 15,
31 16, 17, 18, 19, 20, 21, 22, 23,
32 24, 25, 26, 27, 28, 29, 30, 31
33 };
34
35 struct exec_domain default_exec_domain = {
36 .name = "Linux", /* name */
37 .handler = default_handler, /* lcall7 causes a seg fault. */
38 .pers_low = 0, /* PER_LINUX personality. */
39 .pers_high = 0, /* PER_LINUX personality. */
40 .signal_map = ident_map, /* Identity map signals. */
41 .signal_invmap = ident_map, /* - both ways. */
42 };
43
44
45 static void
46 default_handler(int segment, struct pt_regs *regp)
47 {
48 set_personality(0);
49
50 if (current_thread_info()->exec_domain->handler != default_handler)
51 current_thread_info()->exec_domain->handler(segment, regp);
52 else
53 send_sig(SIGSEGV, current, 1);
54 }
55
56 static struct exec_domain *
57 lookup_exec_domain(u_long personality)
58 {
59 struct exec_domain * ep;
60 u_long pers = personality(personality);
61
62 read_lock(&exec_domains_lock);
63 for (ep = exec_domains; ep; ep = ep->next) {
64 if (pers >= ep->pers_low && pers <= ep->pers_high)
65 if (try_module_get(ep->module))
66 goto out;
67 }
68
69 #ifdef CONFIG_KMOD
70 read_unlock(&exec_domains_lock);
71 request_module("personality-%ld", pers);
72 read_lock(&exec_domains_lock);
73
74 for (ep = exec_domains; ep; ep = ep->next) {
75 if (pers >= ep->pers_low && pers <= ep->pers_high)
76 if (try_module_get(ep->module))
77 goto out;
78 }
79 #endif
80
81 ep = &default_exec_domain;
82 out:
83 read_unlock(&exec_domains_lock);
84 return (ep);
85 }
86
87 int
88 register_exec_domain(struct exec_domain *ep)
89 {
90 struct exec_domain *tmp;
91 int err = -EBUSY;
92
93 if (ep == NULL)
94 return -EINVAL;
95
96 if (ep->next != NULL)
97 return -EBUSY;
98
99 write_lock(&exec_domains_lock);
100 for (tmp = exec_domains; tmp; tmp = tmp->next) {
101 if (tmp == ep)
102 goto out;
103 }
104
105 ep->next = exec_domains;
106 exec_domains = ep;
107 err = 0;
108
109 out:
110 write_unlock(&exec_domains_lock);
111 return (err);
112 }
113
114 int
115 unregister_exec_domain(struct exec_domain *ep)
116 {
117 struct exec_domain **epp;
118
119 epp = &exec_domains;
120 write_lock(&exec_domains_lock);
121 for (epp = &exec_domains; *epp; epp = &(*epp)->next) {
122 if (ep == *epp)
123 goto unregister;
124 }
125 write_unlock(&exec_domains_lock);
126 return -EINVAL;
127
128 unregister:
129 *epp = ep->next;
130 ep->next = NULL;
131 write_unlock(&exec_domains_lock);
132 return 0;
133 }
134
135 int
136 __set_personality(u_long personality)
137 {
138 struct exec_domain *ep, *oep;
139
140 ep = lookup_exec_domain(personality);
141 if (ep == current_thread_info()->exec_domain) {
142 current->personality = personality;
143 return 0;
144 }
145
146 if (atomic_read(¤t->fs->count) != 1) {
147 struct fs_struct *fsp, *ofsp;
148
149 fsp = copy_fs_struct(current->fs);
150 if (fsp == NULL) {
151 module_put(ep->module);
152 return -ENOMEM;
153 }
154
155 task_lock(current);
156 ofsp = current->fs;
157 current->fs = fsp;
158 task_unlock(current);
159
160 put_fs_struct(ofsp);
161 }
162
163 /*
164 * At that point we are guaranteed to be the sole owner of
165 * current->fs.
166 */
167
168 current->personality = personality;
169 oep = current_thread_info()->exec_domain;
170 current_thread_info()->exec_domain = ep;
171 set_fs_altroot();
172
173 module_put(oep->module);
174 return 0;
175 }
176
177 int
178 get_exec_domain_list(char *page)
179 {
180 struct exec_domain *ep;
181 int len = 0;
182
183 read_lock(&exec_domains_lock);
184 for (ep = exec_domains; ep && len < PAGE_SIZE - 80; ep = ep->next)
185 len += sprintf(page + len, "%d-%d\t%-16s\t[%s]\n",
186 ep->pers_low, ep->pers_high, ep->name,
187 module_name(ep->module));
188 read_unlock(&exec_domains_lock);
189 return (len);
190 }
191
192 asmlinkage long
193 sys_personality(u_long personality)
194 {
195 u_long old = current->personality;
196
197 if (personality != 0xffffffff) {
198 set_personality(personality);
199 if (current->personality != personality)
200 return -EINVAL;
201 }
202
203 return (long)old;
204 }
205
206
207 EXPORT_SYMBOL(register_exec_domain);
208 EXPORT_SYMBOL(unregister_exec_domain);
209 EXPORT_SYMBOL(__set_personality);
210
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