[PATCH] refactor capable() to one implementation, add __capable() helper
[linux-2.6.git] / kernel / capability.c
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);