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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 | |
24 | static void default_handler(int, struct pt_regs *); |
25 | |
26 | static struct exec_domain *exec_domains = &default_exec_domain; |
27 | static DEFINE_RWLOCK(exec_domains_lock); |
28 | |
29 | |
30 | static 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 | |
37 | struct 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 | |
47 | static void |
48 | default_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 | |
58 | static struct exec_domain * |
59 | lookup_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; |
84 | out: |
85 | read_unlock(&exec_domains_lock); |
86 | return ep; |
87 | } |
88 | |
89 | int |
90 | register_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 | |
111 | out: |
112 | write_unlock(&exec_domains_lock); |
113 | return err; |
114 | } |
115 | EXPORT_SYMBOL(register_exec_domain); |
116 | |
117 | int |
118 | unregister_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 | |
131 | unregister: |
132 | *epp = ep->next; |
133 | ep->next = NULL; |
134 | write_unlock(&exec_domains_lock); |
135 | return 0; |
136 | } |
137 | EXPORT_SYMBOL(unregister_exec_domain); |
138 | |
139 | int __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 | } |
149 | EXPORT_SYMBOL(__set_personality); |
150 | |
151 | #ifdef CONFIG_PROC_FS |
152 | static 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 | |
165 | static int execdomains_proc_open(struct inode *inode, struct file *file) |
166 | { |
167 | return single_open(file, execdomains_proc_show, NULL); |
168 | } |
169 | |
170 | static 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 | |
177 | static int __init proc_execdomains_init(void) |
178 | { |
179 | proc_create("execdomains", 0, NULL, &execdomains_proc_fops); |
180 | return 0; |
181 | } |
182 | module_init(proc_execdomains_init); |
183 | #endif |
184 | |
185 | SYSCALL_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 | } |
194 |
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