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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
Linus Torvalds1da177e2005-04-16 15:20:36 -070010#include <linux/init.h>
11#include <linux/kernel.h>
12#include <linux/kmod.h>
13#include <linux/module.h>
14#include <linux/personality.h>
Alexey Dobriyan6e627752008-10-04 14:28:09 +040015#include <linux/proc_fs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070016#include <linux/sched.h>
Alexey Dobriyan6e627752008-10-04 14:28:09 +040017#include <linux/seq_file.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070018#include <linux/syscalls.h>
19#include <linux/sysctl.h>
20#include <linux/types.h>
Al Viro5ad4e532009-03-29 19:50:06 -040021#include <linux/fs_struct.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022
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
Oleg Nesterov485d5272010-06-04 14:14:58 -070030static unsigned long ident_map[32] = {
Linus Torvalds1da177e2005-04-16 15:20:36 -070031 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 *
Oleg Nesterov485d5272010-06-04 14:14:58 -070059lookup_exec_domain(unsigned int personality)
Linus Torvalds1da177e2005-04-16 15:20:36 -070060{
Oleg Nesterov485d5272010-06-04 14:14:58 -070061 unsigned int pers = personality(personality);
62 struct exec_domain *ep;
Daniel Walker62769dc2007-10-18 03:06:10 -070063
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 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
Johannes Berga1ef5ad2008-07-08 19:00:17 +020071#ifdef CONFIG_MODULES
Linus Torvalds1da177e2005-04-16 15:20:36 -070072 read_unlock(&exec_domains_lock);
Oleg Nesterov485d5272010-06-04 14:14:58 -070073 request_module("personality-%d", pers);
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 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}
115
116int
117unregister_exec_domain(struct exec_domain *ep)
118{
119 struct exec_domain **epp;
120
121 epp = &exec_domains;
122 write_lock(&exec_domains_lock);
123 for (epp = &exec_domains; *epp; epp = &(*epp)->next) {
124 if (ep == *epp)
125 goto unregister;
126 }
127 write_unlock(&exec_domains_lock);
128 return -EINVAL;
129
130unregister:
131 *epp = ep->next;
132 ep->next = NULL;
133 write_unlock(&exec_domains_lock);
134 return 0;
135}
136
Oleg Nesterov2ee7c922010-08-09 17:20:30 -0700137int __set_personality(unsigned int personality)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138{
Oleg Nesterov2ee7c922010-08-09 17:20:30 -0700139 struct exec_domain *oep = current_thread_info()->exec_domain;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140
Oleg Nesterov2ee7c922010-08-09 17:20:30 -0700141 current_thread_info()->exec_domain = lookup_exec_domain(personality);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142 current->personality = personality;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 module_put(oep->module);
Oleg Nesterov2ee7c922010-08-09 17:20:30 -0700144
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145 return 0;
146}
147
Alexey Dobriyan6e627752008-10-04 14:28:09 +0400148#ifdef CONFIG_PROC_FS
149static int execdomains_proc_show(struct seq_file *m, void *v)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150{
151 struct exec_domain *ep;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152
153 read_lock(&exec_domains_lock);
Alexey Dobriyan6e627752008-10-04 14:28:09 +0400154 for (ep = exec_domains; ep; ep = ep->next)
155 seq_printf(m, "%d-%d\t%-16s\t[%s]\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 ep->pers_low, ep->pers_high, ep->name,
157 module_name(ep->module));
158 read_unlock(&exec_domains_lock);
Alexey Dobriyan6e627752008-10-04 14:28:09 +0400159 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160}
161
Alexey Dobriyan6e627752008-10-04 14:28:09 +0400162static int execdomains_proc_open(struct inode *inode, struct file *file)
163{
164 return single_open(file, execdomains_proc_show, NULL);
165}
166
167static const struct file_operations execdomains_proc_fops = {
168 .open = execdomains_proc_open,
169 .read = seq_read,
170 .llseek = seq_lseek,
171 .release = single_release,
172};
173
174static int __init proc_execdomains_init(void)
175{
176 proc_create("execdomains", 0, NULL, &execdomains_proc_fops);
177 return 0;
178}
179module_init(proc_execdomains_init);
180#endif
181
Oleg Nesterov485d5272010-06-04 14:14:58 -0700182SYSCALL_DEFINE1(personality, unsigned int, personality)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183{
Oleg Nesterov485d5272010-06-04 14:14:58 -0700184 unsigned int old = current->personality;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185
Oleg Nesterov2ee7c922010-08-09 17:20:30 -0700186 if (personality != 0xffffffff)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187 set_personality(personality);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188
Oleg Nesterov485d5272010-06-04 14:14:58 -0700189 return old;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190}
191
192
193EXPORT_SYMBOL(register_exec_domain);
194EXPORT_SYMBOL(unregister_exec_domain);
195EXPORT_SYMBOL(__set_personality);