aboutsummaryrefslogtreecommitdiffstats
path: root/kernel/capability.c
blob: edb845a6e84ae5e649ece39e18384620c5dac74e (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
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
/*
 * linux/kernel/capability.c
 *
 * Copyright (C) 1997  Andrew Main <zefram@fysh.org>
 *
 * Integrated into 2.1.97+,  Andrew G. Morgan <morgan@transmeta.com>
 * 30 May 2002:	Cleanup, Robert M. Love <rml@tech9.net>
 */ 

#include <linux/capability.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <asm/uaccess.h>

unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
kernel_cap_t cap_bset = CAP_INIT_EFF_SET;

EXPORT_SYMBOL(securebits);
EXPORT_SYMBOL(cap_bset);

/*
 * This lock protects task->cap_* for all tasks including current.
 * Locking rule: acquire this prior to tasklist_lock.
 */
static DEFINE_SPINLOCK(task_capability_lock);

/*
 * For sys_getproccap() and sys_setproccap(), any of the three
 * capability set pointers may be NULL -- indicating that that set is
 * uninteresting and/or not to be changed.
 */

/**
 * sys_capget - get the capabilities of a given process.
 * @header: pointer to struct that contains capability version and
 *	target pid data
 * @dataptr: pointer to struct that contains the effective, permitted,
 *	and inheritable capabilities that are returned
 *
 * Returns 0 on success and < 0 on error.
 */
asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
{
     int ret = 0;
     pid_t pid;
     __u32 version;
     struct task_struct *target;
     struct __user_cap_data_struct data;

     if (get_user(version, &header->version))
	     return -EFAULT;

     if (version != _LINUX_CAPABILITY_VERSION) {
	     if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
		     return -EFAULT; 
             return -EINVAL;
     }

     if (get_user(pid, &header->pid))
	     return -EFAULT;

     if (pid < 0) 
             return -EINVAL;

     spin_lock(&task_capability_lock);
     read_lock(&tasklist_lock); 

     if (pid && pid != current->pid) {
	     target = find_task_by_pid(pid);
	     if (!target) {
	          ret = -ESRCH;
	          goto out;
	     }
     } else
	     target = current;

     ret = security_capget(target, &data.effective, &data.inheritable, &data.permitted);

out:
     read_unlock(&tasklist_lock); 
     spin_unlock(&task_capability_lock);

     if (!ret && copy_to_user(dataptr, &data, sizeof data))
          return -EFAULT; 

     return ret;
}

/*
 * cap_set_pg - set capabilities for all processes in a given process
 * group.  We call this holding task_capability_lock and tasklist_lock.
 */
static inline int cap_set_pg(int pgrp, kernel_cap_t *effective,
			      kernel_cap_t *inheritable,
			      kernel_cap_t *permitted)
{
	struct task_struct *g, *target;
	int ret = -EPERM;
	int found = 0;

	do_each_task_pid(pgrp, PIDTYPE_PGID, g) {
		target = g;
		while_each_thread(g, target) {
			if (!security_capset_check(target, effective,
							inheritable,
							permitted)) {
				security_capset_set(target, effective,
							inheritable,
							permitted);
				ret = 0;
			}
			found = 1;
		}
	} while_each_task_pid(pgrp, PIDTYPE_PGID, g);

	if (!found)
	     ret = 0;
	return ret;
}

/*
 * cap_set_all - set capabilities for all processes other than init
 * and self.  We call this holding task_capability_lock and tasklist_lock.
 */
static inline int cap_set_all(kernel_cap_t *effective,
			       kernel_cap_t *inheritable,
			       kernel_cap_t *permitted)
{
     struct task_struct *g, *target;
     int ret = -EPERM;
     int found = 0;

     do_each_thread(g, target) {
             if (target == current || is_init(target))
                     continue;
             found = 1;
	     if (security_capset_check(target, effective, inheritable,
						permitted))
		     continue;
	     ret = 0;
	     security_capset_set(target, effective, inheritable, permitted);
     } while_each_thread(g, target);

     if (!found)
	     ret = 0;
     return ret;
}

/**
 * sys_capset - set capabilities for a process or a group of processes
 * @header: pointer to struct that contains capability version and
 *	target pid data
 * @data: pointer to struct that contains the effective, permitted,
 *	and inheritable capabilities
 *
 * Set capabilities for a given process, all processes, or all
 * processes in a given process group.
 *
 * The restrictions on setting capabilities are specified as:
 *
 * [pid is for the 'target' task.  'current' is the calling task.]
 *
 * I: any raised capabilities must be a subset of the (old current) permitted
 * P: any raised capabilities must be a subset of the (old current) permitted
 * E: must be set to a subset of (new target) permitted
 *
 * Returns 0 on success and < 0 on error.
 */
asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
{
     kernel_cap_t inheritable, permitted, effective;
     __u32 version;
     struct task_struct *target;
     int ret;
     pid_t pid;

     if (get_user(version, &header->version))
	     return -EFAULT; 

     if (version != _LINUX_CAPABILITY_VERSION) {
	     if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
		     return -EFAULT; 
             return -EINVAL;
     }

     if (get_user(pid, &header->pid))
	     return -EFAULT; 

     if (pid && pid != current->pid && !capable(CAP_SETPCAP))
             return -EPERM;

     if (copy_from_user(&effective, &data->effective, sizeof(effective)) ||
	 copy_from_user(&inheritable, &data->inheritable, sizeof(inheritable)) ||
	 copy_from_user(&permitted, &data->permitted, sizeof(permitted)))
	     return -EFAULT; 

     spin_lock(&task_capability_lock);
     read_lock(&tasklist_lock);

     if (pid > 0 && pid != current->pid) {
          target = find_task_by_pid(pid);
          if (!target) {
               ret = -ESRCH;
               goto out;
          }
     } else
               target = current;

     ret = 0;

     /* having verified that the proposed changes are legal,
           we now put them into effect. */
     if (pid < 0) {
             if (pid == -1)  /* all procs other than current and init */
                     ret = cap_set_all(&effective, &inheritable, &permitted);

             else            /* all procs in process group */
                     ret = cap_set_pg(-pid, &effective, &inheritable,
		     					&permitted);
     } else {
	     ret = security_capset_check(target, &effective, &inheritable,
	     						&permitted);
	     if (!ret)
		     security_capset_set(target, &effective, &inheritable,
		     					&permitted);
     }

out:
     read_unlock(&tasklist_lock);
     spin_unlock(&task_capability_lock);

     return ret;
}

int __capable(struct task_struct *t, int cap)
{
	if (security_capable(t, cap) == 0) {
		t->flags |= PF_SUPERPRIV;
		return 1;
	}
	return 0;
}
EXPORT_SYMBOL(__capable);

int capable(int cap)
{
	return __capable(current, cap);
}
EXPORT_SYMBOL(capable);

Privacy Policy