projects/linux·blob v2.6.18-rc6 · refs

209 lines · 4.3 KiB

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 ([email protected])
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/sched.h>
16#include <linux/syscalls.h>
17#include <linux/sysctl.h>
18#include <linux/types.h>
19
20
21static void default_handler(int, struct pt_regs *);
22
23static struct exec_domain *exec_domains = &default_exec_domain;
24static DEFINE_RWLOCK(exec_domains_lock);
25
26
27static 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
34struct exec_domain default_exec_domain = {
35 .name = "Linux", /* name */
36 .handler = default_handler, /* lcall7 causes a seg fault. */
37 .pers_low = 0, /* PER_LINUX personality. */
38 .pers_high = 0, /* PER_LINUX personality. */
39 .signal_map = ident_map, /* Identity map signals. */
40 .signal_invmap = ident_map, /* - both ways. */
41};
42
43
44static void
45default_handler(int segment, struct pt_regs *regp)
46{
47 set_personality(0);
48
49 if (current_thread_info()->exec_domain->handler != default_handler)
50 current_thread_info()->exec_domain->handler(segment, regp);
51 else
52 send_sig(SIGSEGV, current, 1);
53}
54
55static struct exec_domain *
56lookup_exec_domain(u_long personality)
57{
58 struct exec_domain * ep;
59 u_long pers = personality(personality);
60
61 read_lock(&exec_domains_lock);
62 for (ep = exec_domains; ep; ep = ep->next) {
63 if (pers >= ep->pers_low && pers <= ep->pers_high)
64 if (try_module_get(ep->module))
65 goto out;
66 }
67
68#ifdef CONFIG_KMOD
69 read_unlock(&exec_domains_lock);
70 request_module("personality-%ld", pers);
71 read_lock(&exec_domains_lock);
72
73 for (ep = exec_domains; ep; ep = ep->next) {
74 if (pers >= ep->pers_low && pers <= ep->pers_high)
75 if (try_module_get(ep->module))
76 goto out;
77 }
78#endif
79
80 ep = &default_exec_domain;
81out:
82 read_unlock(&exec_domains_lock);
83 return (ep);
84}
85
86int
87register_exec_domain(struct exec_domain *ep)
88{
89 struct exec_domain *tmp;
90 int err = -EBUSY;
91
92 if (ep == NULL)
93 return -EINVAL;
94
95 if (ep->next != NULL)
96 return -EBUSY;
97
98 write_lock(&exec_domains_lock);
99 for (tmp = exec_domains; tmp; tmp = tmp->next) {
100 if (tmp == ep)
101 goto out;
102 }
103
104 ep->next = exec_domains;
105 exec_domains = ep;
106 err = 0;
107
108out:
109 write_unlock(&exec_domains_lock);
110 return (err);
111}
112
113int
114unregister_exec_domain(struct exec_domain *ep)
115{
116 struct exec_domain **epp;
117
118 epp = &exec_domains;
119 write_lock(&exec_domains_lock);
120 for (epp = &exec_domains; *epp; epp = &(*epp)->next) {
121 if (ep == *epp)
122 goto unregister;
123 }
124 write_unlock(&exec_domains_lock);
125 return -EINVAL;
126
127unregister:
128 *epp = ep->next;
129 ep->next = NULL;
130 write_unlock(&exec_domains_lock);
131 return 0;
132}
133
134int
135__set_personality(u_long personality)
136{
137 struct exec_domain *ep, *oep;
138
139 ep = lookup_exec_domain(personality);
140 if (ep == current_thread_info()->exec_domain) {
141 current->personality = personality;
142 module_put(ep->module);
143 return 0;
144 }
145
146 if (atomic_read(&current->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
177int
178get_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
192asmlinkage long
193sys_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
207EXPORT_SYMBOL(register_exec_domain);
208EXPORT_SYMBOL(unregister_exec_domain);
209EXPORT_SYMBOL(__set_personality);