aboutsummaryrefslogtreecommitdiff
path: root/kernel/exec_domain.c
blob: 83d4382f56998d8bcde22b4d9cc4822360d41afa (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
/*
 * Handling of different ABIs (personalities).
 *
 * We group personalities into execution domains which have their
 * own handlers for kernel entry points, signal mapping, etc...
 *
 * 2001-05-06	Complete rewrite,  Christoph Hellwig (hch@infradead.org)
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/kmod.h>
#include <linux/module.h>
#include <linux/personality.h>
#include <linux/proc_fs.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/syscalls.h>
#include <linux/sysctl.h>
#include <linux/types.h>
#include <linux/fs_struct.h>


static void default_handler(int, struct pt_regs *);

static struct exec_domain *exec_domains = &default_exec_domain;
static DEFINE_RWLOCK(exec_domains_lock);


static unsigned long ident_map[32] = {
	0,	1,	2,	3,	4,	5,	6,	7,
	8,	9,	10,	11,	12,	13,	14,	15,
	16,	17,	18,	19,	20,	21,	22,	23,
	24,	25,	26,	27,	28,	29,	30,	31
};

struct exec_domain default_exec_domain = {
	.name		= "Linux",		/* name */
	.handler	= default_handler,	/* lcall7 causes a seg fault. */
	.pers_low	= 0,			/* PER_LINUX personality. */
	.pers_high	= 0,			/* PER_LINUX personality. */
	.signal_map	= ident_map,		/* Identity map signals. */
	.signal_invmap	= ident_map,		/*  - both ways. */
};


static void
default_handler(int segment, struct pt_regs *regp)
{
	set_personality(0);

	if (current_thread_info()->exec_domain->handler != default_handler)
		current_thread_info()->exec_domain->handler(segment, regp);
	else
		send_sig(SIGSEGV, current, 1);
}

static struct exec_domain *
lookup_exec_domain(unsigned int personality)
{
	unsigned int pers = personality(personality);
	struct exec_domain *ep;

	read_lock(&exec_domains_lock);
	for (ep = exec_domains; ep; ep = ep->next) {
		if (pers >= ep->pers_low && pers <= ep->pers_high)
			if (try_module_get(ep->module))
				goto out;
	}

#ifdef CONFIG_MODULES
	read_unlock(&exec_domains_lock);
	request_module("personality-%d", pers);
	read_lock(&exec_domains_lock);

	for (ep = exec_domains; ep; ep = ep->next) {
		if (pers >= ep->pers_low && pers <= ep->pers_high)
			if (try_module_get(ep->module))
				goto out;
	}
#endif

	ep = &default_exec_domain;
out:
	read_unlock(&exec_domains_lock);
	return ep;
}

int
register_exec_domain(struct exec_domain *ep)
{
	struct exec_domain	*tmp;
	int			err = -EBUSY;

	if (ep == NULL)
		return -EINVAL;

	if (ep->next != NULL)
		return -EBUSY;

	write_lock(&exec_domains_lock);
	for (tmp = exec_domains; tmp; tmp = tmp->next) {
		if (tmp == ep)
			goto out;
	}

	ep->next = exec_domains;
	exec_domains = ep;
	err = 0;

out:
	write_unlock(&exec_domains_lock);
	return err;
}
EXPORT_SYMBOL(register_exec_domain);

int
unregister_exec_domain(struct exec_domain *ep)
{
	struct exec_domain	**epp;

	epp = &exec_domains;
	write_lock(&exec_domains_lock);
	for (epp = &exec_domains; *epp; epp = &(*epp)->next) {
		if (ep == *epp)
			goto unregister;
	}
	write_unlock(&exec_domains_lock);
	return -EINVAL;

unregister:
	*epp = ep->next;
	ep->next = NULL;
	write_unlock(&exec_domains_lock);
	return 0;
}
EXPORT_SYMBOL(unregister_exec_domain);

int __set_personality(unsigned int personality)
{
	struct exec_domain *oep = current_thread_info()->exec_domain;

	current_thread_info()->exec_domain = lookup_exec_domain(personality);
	current->personality = personality;
	module_put(oep->module);

	return 0;
}
EXPORT_SYMBOL(__set_personality);

#ifdef CONFIG_PROC_FS
static int execdomains_proc_show(struct seq_file *m, void *v)
{
	struct exec_domain	*ep;

	read_lock(&exec_domains_lock);
	for (ep = exec_domains; ep; ep = ep->next)
		seq_printf(m, "%d-%d\t%-16s\t[%s]\n",
			       ep->pers_low, ep->pers_high, ep->name,
			       module_name(ep->module));
	read_unlock(&exec_domains_lock);
	return 0;
}

static int execdomains_proc_open(struct inode *inode, struct file *file)
{
	return single_open(file, execdomains_proc_show, NULL);
}

static const struct file_operations execdomains_proc_fops = {
	.open		= execdomains_proc_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
};

static int __init proc_execdomains_init(void)
{
	proc_create("execdomains", 0, NULL, &execdomains_proc_fops);
	return 0;
}
module_init(proc_execdomains_init);
#endif

SYSCALL_DEFINE1(personality, unsigned int, personality)
{
	unsigned int old = current->personality;

	if (personality != 0xffffffff)
		set_personality(personality);

	return old;
}