14853be5944d8ffd6da305fde581ea2a29d62d87
[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@kernel.org>
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 /*
18  * This lock protects task->cap_* for all tasks including current.
19  * Locking rule: acquire this prior to tasklist_lock.
20  */
21 static DEFINE_SPINLOCK(task_capability_lock);
22
23 /*
24  * For sys_getproccap() and sys_setproccap(), any of the three
25  * capability set pointers may be NULL -- indicating that that set is
26  * uninteresting and/or not to be changed.
27  */
28
29 /**
30  * sys_capget - get the capabilities of a given process.
31  * @header: pointer to struct that contains capability version and
32  *      target pid data
33  * @dataptr: pointer to struct that contains the effective, permitted,
34  *      and inheritable capabilities that are returned
35  *
36  * Returns 0 on success and < 0 on error.
37  */
38 asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
39 {
40      int ret = 0;
41      pid_t pid;
42      __u32 version;
43      struct task_struct *target;
44      struct __user_cap_data_struct data;
45
46      if (get_user(version, &header->version))
47              return -EFAULT;
48
49      if (version != _LINUX_CAPABILITY_VERSION) {
50              if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
51                      return -EFAULT; 
52              return -EINVAL;
53      }
54
55      if (get_user(pid, &header->pid))
56              return -EFAULT;
57
58      if (pid < 0) 
59              return -EINVAL;
60
61      spin_lock(&task_capability_lock);
62      read_lock(&tasklist_lock); 
63
64      if (pid && pid != current->pid) {
65              target = find_task_by_pid(pid);
66              if (!target) {
67                   ret = -ESRCH;
68                   goto out;
69              }
70      } else
71              target = current;
72
73      ret = security_capget(target, &data.effective, &data.inheritable, &data.permitted);
74
75 out:
76      read_unlock(&tasklist_lock); 
77      spin_unlock(&task_capability_lock);
78
79      if (!ret && copy_to_user(dataptr, &data, sizeof data))
80           return -EFAULT; 
81
82      return ret;
83 }
84
85 /*
86  * cap_set_pg - set capabilities for all processes in a given process
87  * group.  We call this holding task_capability_lock and tasklist_lock.
88  */
89 static inline int cap_set_pg(int pgrp_nr, kernel_cap_t *effective,
90                               kernel_cap_t *inheritable,
91                               kernel_cap_t *permitted)
92 {
93         struct task_struct *g, *target;
94         int ret = -EPERM;
95         int found = 0;
96         struct pid *pgrp;
97
98         pgrp = find_pid(pgrp_nr);
99         do_each_pid_task(pgrp, PIDTYPE_PGID, g) {
100                 target = g;
101                 while_each_thread(g, target) {
102                         if (!security_capset_check(target, effective,
103                                                         inheritable,
104                                                         permitted)) {
105                                 security_capset_set(target, effective,
106                                                         inheritable,
107                                                         permitted);
108                                 ret = 0;
109                         }
110                         found = 1;
111                 }
112         } while_each_pid_task(pgrp, PIDTYPE_PGID, g);
113
114         if (!found)
115              ret = 0;
116         return ret;
117 }
118
119 /*
120  * cap_set_all - set capabilities for all processes other than init
121  * and self.  We call this holding task_capability_lock and tasklist_lock.
122  */
123 static inline int cap_set_all(kernel_cap_t *effective,
124                                kernel_cap_t *inheritable,
125                                kernel_cap_t *permitted)
126 {
127      struct task_struct *g, *target;
128      int ret = -EPERM;
129      int found = 0;
130
131      do_each_thread(g, target) {
132              if (target == current || is_init(target))
133                      continue;
134              found = 1;
135              if (security_capset_check(target, effective, inheritable,
136                                                 permitted))
137                      continue;
138              ret = 0;
139              security_capset_set(target, effective, inheritable, permitted);
140      } while_each_thread(g, target);
141
142      if (!found)
143              ret = 0;
144      return ret;
145 }
146
147 /**
148  * sys_capset - set capabilities for a process or a group of processes
149  * @header: pointer to struct that contains capability version and
150  *      target pid data
151  * @data: pointer to struct that contains the effective, permitted,
152  *      and inheritable capabilities
153  *
154  * Set capabilities for a given process, all processes, or all
155  * processes in a given process group.
156  *
157  * The restrictions on setting capabilities are specified as:
158  *
159  * [pid is for the 'target' task.  'current' is the calling task.]
160  *
161  * I: any raised capabilities must be a subset of the (old current) permitted
162  * P: any raised capabilities must be a subset of the (old current) permitted
163  * E: must be set to a subset of (new target) permitted
164  *
165  * Returns 0 on success and < 0 on error.
166  */
167 asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
168 {
169      kernel_cap_t inheritable, permitted, effective;
170      __u32 version;
171      struct task_struct *target;
172      int ret;
173      pid_t pid;
174
175      if (get_user(version, &header->version))
176              return -EFAULT; 
177
178      if (version != _LINUX_CAPABILITY_VERSION) {
179              if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
180                      return -EFAULT; 
181              return -EINVAL;
182      }
183
184      if (get_user(pid, &header->pid))
185              return -EFAULT; 
186
187      if (pid && pid != current->pid && !capable(CAP_SETPCAP))
188              return -EPERM;
189
190      if (copy_from_user(&effective, &data->effective, sizeof(effective)) ||
191          copy_from_user(&inheritable, &data->inheritable, sizeof(inheritable)) ||
192          copy_from_user(&permitted, &data->permitted, sizeof(permitted)))
193              return -EFAULT; 
194
195      spin_lock(&task_capability_lock);
196      read_lock(&tasklist_lock);
197
198      if (pid > 0 && pid != current->pid) {
199           target = find_task_by_pid(pid);
200           if (!target) {
201                ret = -ESRCH;
202                goto out;
203           }
204      } else
205                target = current;
206
207      ret = 0;
208
209      /* having verified that the proposed changes are legal,
210            we now put them into effect. */
211      if (pid < 0) {
212              if (pid == -1)  /* all procs other than current and init */
213                      ret = cap_set_all(&effective, &inheritable, &permitted);
214
215              else            /* all procs in process group */
216                      ret = cap_set_pg(-pid, &effective, &inheritable,
217                                                         &permitted);
218      } else {
219              ret = security_capset_check(target, &effective, &inheritable,
220                                                         &permitted);
221              if (!ret)
222                      security_capset_set(target, &effective, &inheritable,
223                                                         &permitted);
224      }
225
226 out:
227      read_unlock(&tasklist_lock);
228      spin_unlock(&task_capability_lock);
229
230      return ret;
231 }
232
233 int __capable(struct task_struct *t, int cap)
234 {
235         if (security_capable(t, cap) == 0) {
236                 t->flags |= PF_SUPERPRIV;
237                 return 1;
238         }
239         return 0;
240 }
241
242 int capable(int cap)
243 {
244         return __capable(current, cap);
245 }
246 EXPORT_SYMBOL(capable);