1 /*
2 * linux/kernel/capability.c
3 *
4 * Copyright (C) 1997 Andrew Main <zefram@fysh.org>
5 *
6 * Integrated into 2.1.97+, Andrew G. Morgan <morgan@transmeta.com>
7 * 30 May 2002: Cleanup, Robert M. Love <rml@tech9.net>
8 */
9
10 #include <linux/capability.h>
11 #include <linux/mm.h>
12 #include <linux/module.h>
13 #include <linux/security.h>
14 #include <linux/syscalls.h>
15 #include <asm/uaccess.h>
16
17 unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
18 kernel_cap_t cap_bset = CAP_INIT_EFF_SET;
19
20 EXPORT_SYMBOL(securebits);
21 EXPORT_SYMBOL(cap_bset);
22
23 /*
24 * This lock protects task->cap_* for all tasks including current.
25 * Locking rule: acquire this prior to tasklist_lock.
26 */
27 static DEFINE_SPINLOCK(task_capability_lock);
28
29 /*
30 * For sys_getproccap() and sys_setproccap(), any of the three
31 * capability set pointers may be NULL -- indicating that that set is
32 * uninteresting and/or not to be changed.
33 */
34
35 /**
36 * sys_capget - get the capabilities of a given process.
37 * @header: pointer to struct that contains capability version and
38 * target pid data
39 * @dataptr: pointer to struct that contains the effective, permitted,
40 * and inheritable capabilities that are returned
41 *
42 * Returns 0 on success and < 0 on error.
43 */
44 asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
45 {
46 int ret = 0;
47 pid_t pid;
48 __u32 version;
49 task_t *target;
50 struct __user_cap_data_struct data;
51
52 if (get_user(version, &header->version))
53 return -EFAULT;
54
55 if (version != _LINUX_CAPABILITY_VERSION) {
56 if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
57 return -EFAULT;
58 return -EINVAL;
59 }
60
61 if (get_user(pid, &header->pid))
62 return -EFAULT;
63
64 if (pid < 0)
65 return -EINVAL;
66
67 spin_lock(&task_capability_lock);
68 read_lock(&tasklist_lock);
69
70 if (pid && pid != current->pid) {
71 target = find_task_by_pid(pid);
72 if (!target) {
73 ret = -ESRCH;
74 goto out;
75 }
76 } else
77 target = current;
78
79 ret = security_capget(target, &data.effective, &data.inheritable, &data.permitted);
80
81 out:
82 read_unlock(&tasklist_lock);
83 spin_unlock(&task_capability_lock);
84
85 if (!ret && copy_to_user(dataptr, &data, sizeof data))
86 return -EFAULT;
87
88 return ret;
89 }
90
91 /*
92 * cap_set_pg - set capabilities for all processes in a given process
93 * group. We call this holding task_capability_lock and tasklist_lock.
94 */
95 static inline int cap_set_pg(int pgrp, kernel_cap_t *effective,
96 kernel_cap_t *inheritable,
97 kernel_cap_t *permitted)
98 {
99 task_t *g, *target;
100 int ret = -EPERM;
101 int found = 0;
102
103 do_each_task_pid(pgrp, PIDTYPE_PGID, g) {
104 target = g;
105 while_each_thread(g, target) {
106 if (!security_capset_check(target, effective,
107 inheritable,
108 permitted)) {
109 security_capset_set(target, effective,
110 inheritable,
111 permitted);
112 ret = 0;
113 }
114 found = 1;
115 }
116 } while_each_task_pid(pgrp, PIDTYPE_PGID, g);
117
118 if (!found)
119 ret = 0;
120 return ret;
121 }
122
123 /*
124 * cap_set_all - set capabilities for all processes other than init
125 * and self. We call this holding task_capability_lock and tasklist_lock.
126 */
127 static inline int cap_set_all(kernel_cap_t *effective,
128 kernel_cap_t *inheritable,
129 kernel_cap_t *permitted)
130 {
131 task_t *g, *target;
132 int ret = -EPERM;
133 int found = 0;
134
135 do_each_thread(g, target) {
136 if (target == current || target->pid == 1)
137 continue;
138 found = 1;
139 if (security_capset_check(target, effective, inheritable,
140 permitted))
141 continue;
142 ret = 0;
143 security_capset_set(target, effective, inheritable, permitted);
144 } while_each_thread(g, target);
145
146 if (!found)
147 ret = 0;
148 return ret;
149 }
150
151 /**
152 * sys_capset - set capabilities for a process or a group of processes
153 * @header: pointer to struct that contains capability version and
154 * target pid data
155 * @data: pointer to struct that contains the effective, permitted,
156 * and inheritable capabilities
157 *
158 * Set capabilities for a given process, all processes, or all
159 * processes in a given process group.
160 *
161 * The restrictions on setting capabilities are specified as:
162 *
163 * [pid is for the 'target' task. 'current' is the calling task.]
164 *
165 * I: any raised capabilities must be a subset of the (old current) permitted
166 * P: any raised capabilities must be a subset of the (old current) permitted
167 * E: must be set to a subset of (new target) permitted
168 *
169 * Returns 0 on success and < 0 on error.
170 */
171 asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
172 {
173 kernel_cap_t inheritable, permitted, effective;
174 __u32 version;
175 task_t *target;
176 int ret;
177 pid_t pid;
178
179 if (get_user(version, &header->version))
180 return -EFAULT;
181
182 if (version != _LINUX_CAPABILITY_VERSION) {
183 if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
184 return -EFAULT;
185 return -EINVAL;
186 }
187
188 if (get_user(pid, &header->pid))
189 return -EFAULT;
190
191 if (pid && pid != current->pid && !capable(CAP_SETPCAP))
192 return -EPERM;
193
194 if (copy_from_user(&effective, &data->effective, sizeof(effective)) ||
195 copy_from_user(&inheritable, &data->inheritable, sizeof(inheritable)) ||
196 copy_from_user(&permitted, &data->permitted, sizeof(permitted)))
197 return -EFAULT;
198
199 spin_lock(&task_capability_lock);
200 read_lock(&tasklist_lock);
201
202 if (pid > 0 && pid != current->pid) {
203 target = find_task_by_pid(pid);
204 if (!target) {
205 ret = -ESRCH;
206 goto out;
207 }
208 } else
209 target = current;
210
211 ret = 0;
212
213 /* having verified that the proposed changes are legal,
214 we now put them into effect. */
215 if (pid < 0) {
216 if (pid == -1) /* all procs other than current and init */
217 ret = cap_set_all(&effective, &inheritable, &permitted);
218
219 else /* all procs in process group */
220 ret = cap_set_pg(-pid, &effective, &inheritable,
221 &permitted);
222 } else {
223 ret = security_capset_check(target, &effective, &inheritable,
224 &permitted);
225 if (!ret)
226 security_capset_set(target, &effective, &inheritable,
227 &permitted);
228 }
229
230 out:
231 read_unlock(&tasklist_lock);
232 spin_unlock(&task_capability_lock);
233
234 return ret;
235 }
236
237 int __capable(struct task_struct *t, int cap)
238 {
239 if (security_capable(t, cap) == 0) {
240 t->flags |= PF_SUPERPRIV;
241 return 1;
242 }
243 return 0;
244 }
245 EXPORT_SYMBOL(__capable);
246
247 int capable(int cap)
248 {
249 return __capable(current, cap);
250 }
251 EXPORT_SYMBOL(capable);
252
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