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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
Randy.Dunlapc59ede72006-01-11 12:17:46 -080010#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070011#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
17unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
18kernel_cap_t cap_bset = CAP_INIT_EFF_SET;
19
20EXPORT_SYMBOL(securebits);
21EXPORT_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 */
27static 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
Randy Dunlap207a7ba2005-07-27 11:45:10 -070035/**
Linus Torvalds1da177e2005-04-16 15:20:36 -070036 * sys_capget - get the capabilities of a given process.
Randy Dunlap207a7ba2005-07-27 11:45:10 -070037 * @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.
Linus Torvalds1da177e2005-04-16 15:20:36 -070043 */
44asmlinkage 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;
Ingo Molnar36c8b582006-07-03 00:25:41 -070049 struct task_struct *target;
Linus Torvalds1da177e2005-04-16 15:20:36 -070050 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
81out:
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 */
Eric W. Biederman41487c62007-02-12 00:53:01 -080095static inline int cap_set_pg(int pgrp_nr, kernel_cap_t *effective,
Linus Torvalds1da177e2005-04-16 15:20:36 -070096 kernel_cap_t *inheritable,
97 kernel_cap_t *permitted)
98{
Ingo Molnar36c8b582006-07-03 00:25:41 -070099 struct task_struct *g, *target;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100 int ret = -EPERM;
101 int found = 0;
Eric W. Biederman41487c62007-02-12 00:53:01 -0800102 struct pid *pgrp;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103
Eric W. Biederman41487c62007-02-12 00:53:01 -0800104 pgrp = find_pid(pgrp_nr);
105 do_each_pid_task(pgrp, PIDTYPE_PGID, g) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106 target = g;
107 while_each_thread(g, target) {
108 if (!security_capset_check(target, effective,
109 inheritable,
110 permitted)) {
111 security_capset_set(target, effective,
112 inheritable,
113 permitted);
114 ret = 0;
115 }
116 found = 1;
117 }
Eric W. Biederman41487c62007-02-12 00:53:01 -0800118 } while_each_pid_task(pgrp, PIDTYPE_PGID, g);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119
120 if (!found)
121 ret = 0;
122 return ret;
123}
124
125/*
126 * cap_set_all - set capabilities for all processes other than init
127 * and self. We call this holding task_capability_lock and tasklist_lock.
128 */
129static inline int cap_set_all(kernel_cap_t *effective,
130 kernel_cap_t *inheritable,
131 kernel_cap_t *permitted)
132{
Ingo Molnar36c8b582006-07-03 00:25:41 -0700133 struct task_struct *g, *target;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134 int ret = -EPERM;
135 int found = 0;
136
137 do_each_thread(g, target) {
Sukadev Bhattiproluf400e192006-09-29 02:00:07 -0700138 if (target == current || is_init(target))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139 continue;
140 found = 1;
141 if (security_capset_check(target, effective, inheritable,
142 permitted))
143 continue;
144 ret = 0;
145 security_capset_set(target, effective, inheritable, permitted);
146 } while_each_thread(g, target);
147
148 if (!found)
149 ret = 0;
150 return ret;
151}
152
Randy Dunlap207a7ba2005-07-27 11:45:10 -0700153/**
154 * sys_capset - set capabilities for a process or a group of processes
155 * @header: pointer to struct that contains capability version and
156 * target pid data
157 * @data: pointer to struct that contains the effective, permitted,
158 * and inheritable capabilities
159 *
160 * Set capabilities for a given process, all processes, or all
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161 * processes in a given process group.
162 *
163 * The restrictions on setting capabilities are specified as:
164 *
165 * [pid is for the 'target' task. 'current' is the calling task.]
166 *
167 * I: any raised capabilities must be a subset of the (old current) permitted
168 * P: any raised capabilities must be a subset of the (old current) permitted
169 * E: must be set to a subset of (new target) permitted
Randy Dunlap207a7ba2005-07-27 11:45:10 -0700170 *
171 * Returns 0 on success and < 0 on error.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172 */
173asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
174{
175 kernel_cap_t inheritable, permitted, effective;
176 __u32 version;
Ingo Molnar36c8b582006-07-03 00:25:41 -0700177 struct task_struct *target;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178 int ret;
179 pid_t pid;
180
181 if (get_user(version, &header->version))
182 return -EFAULT;
183
184 if (version != _LINUX_CAPABILITY_VERSION) {
185 if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
186 return -EFAULT;
187 return -EINVAL;
188 }
189
190 if (get_user(pid, &header->pid))
191 return -EFAULT;
192
193 if (pid && pid != current->pid && !capable(CAP_SETPCAP))
194 return -EPERM;
195
196 if (copy_from_user(&effective, &data->effective, sizeof(effective)) ||
197 copy_from_user(&inheritable, &data->inheritable, sizeof(inheritable)) ||
198 copy_from_user(&permitted, &data->permitted, sizeof(permitted)))
199 return -EFAULT;
200
201 spin_lock(&task_capability_lock);
202 read_lock(&tasklist_lock);
203
204 if (pid > 0 && pid != current->pid) {
205 target = find_task_by_pid(pid);
206 if (!target) {
207 ret = -ESRCH;
208 goto out;
209 }
210 } else
211 target = current;
212
213 ret = 0;
214
215 /* having verified that the proposed changes are legal,
216 we now put them into effect. */
217 if (pid < 0) {
218 if (pid == -1) /* all procs other than current and init */
219 ret = cap_set_all(&effective, &inheritable, &permitted);
220
221 else /* all procs in process group */
222 ret = cap_set_pg(-pid, &effective, &inheritable,
223 &permitted);
224 } else {
225 ret = security_capset_check(target, &effective, &inheritable,
226 &permitted);
227 if (!ret)
228 security_capset_set(target, &effective, &inheritable,
229 &permitted);
230 }
231
232out:
233 read_unlock(&tasklist_lock);
234 spin_unlock(&task_capability_lock);
235
236 return ret;
237}
Chris Wright12b59892006-03-25 03:07:41 -0800238
239int __capable(struct task_struct *t, int cap)
240{
241 if (security_capable(t, cap) == 0) {
242 t->flags |= PF_SUPERPRIV;
243 return 1;
244 }
245 return 0;
246}
247EXPORT_SYMBOL(__capable);
248
249int capable(int cap)
250{
251 return __capable(current, cap);
252}
253EXPORT_SYMBOL(capable);