xref: /openbmc/linux/kernel/capability.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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      struct task_struct *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_nr, kernel_cap_t *effective,
96 			      kernel_cap_t *inheritable,
97 			      kernel_cap_t *permitted)
98 {
99 	struct task_struct *g, *target;
100 	int ret = -EPERM;
101 	int found = 0;
102 	struct pid *pgrp;
103 
104 	pgrp = find_pid(pgrp_nr);
105 	do_each_pid_task(pgrp, PIDTYPE_PGID, g) {
106 		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 		}
118 	} while_each_pid_task(pgrp, PIDTYPE_PGID, g);
119 
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  */
129 static inline int cap_set_all(kernel_cap_t *effective,
130 			       kernel_cap_t *inheritable,
131 			       kernel_cap_t *permitted)
132 {
133      struct task_struct *g, *target;
134      int ret = -EPERM;
135      int found = 0;
136 
137      do_each_thread(g, target) {
138              if (target == current || is_init(target))
139                      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 
153 /**
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
161  * 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
170  *
171  * Returns 0 on success and < 0 on error.
172  */
173 asmlinkage 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;
177      struct task_struct *target;
178      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 
232 out:
233      read_unlock(&tasklist_lock);
234      spin_unlock(&task_capability_lock);
235 
236      return ret;
237 }
238 
239 int __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 }
247 EXPORT_SYMBOL(__capable);
248 
249 int capable(int cap)
250 {
251 	return __capable(current, cap);
252 }
253 EXPORT_SYMBOL(capable);
254