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
default_handler(int segment,struct pt_regs * regp)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 *
lookup_exec_domain(unsigned int personality)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 /*
72 * Disable the request_module here to avoid trying to
73 * load the personality-8 module, which doesn't exist,
74 * and results in selinux audit noise.
75 * Disabling this here avoids folks adding module_request
76 * to their sepolicy, which is maybe too generous
77 */
78 #if 0
79 read_unlock(&exec_domains_lock);
80 request_module("personality-%d", pers);
81 read_lock(&exec_domains_lock);
82
83 for (ep = exec_domains; ep; ep = ep->next) {
84 if (pers >= ep->pers_low && pers <= ep->pers_high)
85 if (try_module_get(ep->module))
86 goto out;
87 }
88 #endif
89
90 ep = &default_exec_domain;
91 out:
92 read_unlock(&exec_domains_lock);
93 return ep;
94 }
95
96 int
register_exec_domain(struct exec_domain * ep)97 register_exec_domain(struct exec_domain *ep)
98 {
99 struct exec_domain *tmp;
100 int err = -EBUSY;
101
102 if (ep == NULL)
103 return -EINVAL;
104
105 if (ep->next != NULL)
106 return -EBUSY;
107
108 write_lock(&exec_domains_lock);
109 for (tmp = exec_domains; tmp; tmp = tmp->next) {
110 if (tmp == ep)
111 goto out;
112 }
113
114 ep->next = exec_domains;
115 exec_domains = ep;
116 err = 0;
117
118 out:
119 write_unlock(&exec_domains_lock);
120 return err;
121 }
122 EXPORT_SYMBOL(register_exec_domain);
123
124 int
unregister_exec_domain(struct exec_domain * ep)125 unregister_exec_domain(struct exec_domain *ep)
126 {
127 struct exec_domain **epp;
128
129 epp = &exec_domains;
130 write_lock(&exec_domains_lock);
131 for (epp = &exec_domains; *epp; epp = &(*epp)->next) {
132 if (ep == *epp)
133 goto unregister;
134 }
135 write_unlock(&exec_domains_lock);
136 return -EINVAL;
137
138 unregister:
139 *epp = ep->next;
140 ep->next = NULL;
141 write_unlock(&exec_domains_lock);
142 return 0;
143 }
144 EXPORT_SYMBOL(unregister_exec_domain);
145
__set_personality(unsigned int personality)146 int __set_personality(unsigned int personality)
147 {
148 struct exec_domain *oep = current_thread_info()->exec_domain;
149
150 current_thread_info()->exec_domain = lookup_exec_domain(personality);
151 current->personality = personality;
152 module_put(oep->module);
153
154 return 0;
155 }
156 EXPORT_SYMBOL(__set_personality);
157
158 #ifdef CONFIG_PROC_FS
execdomains_proc_show(struct seq_file * m,void * v)159 static int execdomains_proc_show(struct seq_file *m, void *v)
160 {
161 struct exec_domain *ep;
162
163 read_lock(&exec_domains_lock);
164 for (ep = exec_domains; ep; ep = ep->next)
165 seq_printf(m, "%d-%d\t%-16s\t[%s]\n",
166 ep->pers_low, ep->pers_high, ep->name,
167 module_name(ep->module));
168 read_unlock(&exec_domains_lock);
169 return 0;
170 }
171
execdomains_proc_open(struct inode * inode,struct file * file)172 static int execdomains_proc_open(struct inode *inode, struct file *file)
173 {
174 return single_open(file, execdomains_proc_show, NULL);
175 }
176
177 static const struct file_operations execdomains_proc_fops = {
178 .open = execdomains_proc_open,
179 .read = seq_read,
180 .llseek = seq_lseek,
181 .release = single_release,
182 };
183
proc_execdomains_init(void)184 static int __init proc_execdomains_init(void)
185 {
186 proc_create("execdomains", 0, NULL, &execdomains_proc_fops);
187 return 0;
188 }
189 module_init(proc_execdomains_init);
190 #endif
191
SYSCALL_DEFINE1(personality,unsigned int,personality)192 SYSCALL_DEFINE1(personality, unsigned int, personality)
193 {
194 unsigned int old = current->personality;
195
196 if (personality != 0xffffffff)
197 set_personality(personality);
198
199 return old;
200 }
201