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git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
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
24static void default_handler(int, struct pt_regs *);
25
26static struct exec_domain *exec_domains = &default_exec_domain;
27static DEFINE_RWLOCK(exec_domains_lock);
28
29
30static 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
37struct 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
47static void
48default_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
58static struct exec_domain *
59lookup_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;
84out:
85 read_unlock(&exec_domains_lock);
86 return ep;
87}
88
89int
90register_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
111out:
112 write_unlock(&exec_domains_lock);
113 return err;
114}
115EXPORT_SYMBOL(register_exec_domain);
116
117int
118unregister_exec_domain(struct exec_domain *ep)
119{
120 struct exec_domain **epp;
121
122 epp = &exec_domains;
123 write_lock(&exec_domains_lock);
124 for (epp = &exec_domains; *epp; epp = &(*epp)->next) {
125 if (ep == *epp)
126 goto unregister;
127 }
128 write_unlock(&exec_domains_lock);
129 return -EINVAL;
130
131unregister:
132 *epp = ep->next;
133 ep->next = NULL;
134 write_unlock(&exec_domains_lock);
135 return 0;
136}
137EXPORT_SYMBOL(unregister_exec_domain);
138
139int __set_personality(unsigned int personality)
140{
141 struct exec_domain *oep = current_thread_info()->exec_domain;
142
143 current_thread_info()->exec_domain = lookup_exec_domain(personality);
144 current->personality = personality;
145 module_put(oep->module);
146
147 return 0;
148}
149EXPORT_SYMBOL(__set_personality);
150
151#ifdef CONFIG_PROC_FS
152static int execdomains_proc_show(struct seq_file *m, void *v)
153{
154 struct exec_domain *ep;
155
156 read_lock(&exec_domains_lock);
157 for (ep = exec_domains; ep; ep = ep->next)
158 seq_printf(m, "%d-%d\t%-16s\t[%s]\n",
159 ep->pers_low, ep->pers_high, ep->name,
160 module_name(ep->module));
161 read_unlock(&exec_domains_lock);
162 return 0;
163}
164
165static int execdomains_proc_open(struct inode *inode, struct file *file)
166{
167 return single_open(file, execdomains_proc_show, NULL);
168}
169
170static const struct file_operations execdomains_proc_fops = {
171 .open = execdomains_proc_open,
172 .read = seq_read,
173 .llseek = seq_lseek,
174 .release = single_release,
175};
176
177static int __init proc_execdomains_init(void)
178{
179 proc_create("execdomains", 0, NULL, &execdomains_proc_fops);
180 return 0;
181}
182module_init(proc_execdomains_init);
183#endif
184
185SYSCALL_DEFINE1(personality, unsigned int, personality)
186{
187 unsigned int old = current->personality;
188
189 if (personality != 0xffffffff)
190 set_personality(personality);
191
192 return old;
193}