2 * linux/kernel/capability.c
4 * Copyright (C) 1997 Andrew Main <zefram@fysh.org>
6 * Integrated into 2.1.97+, Andrew G. Morgan <morgan@kernel.org>
7 * 30 May 2002: Cleanup, Robert M. Love <rml@tech9.net>
10 #include <linux/audit.h>
11 #include <linux/capability.h>
13 #include <linux/export.h>
14 #include <linux/security.h>
15 #include <linux/syscalls.h>
16 #include <linux/pid_namespace.h>
17 #include <linux/user_namespace.h>
18 #include <asm/uaccess.h>
21 * Leveraged for setting/resetting capabilities
24 const kernel_cap_t __cap_empty_set
= CAP_EMPTY_SET
;
26 EXPORT_SYMBOL(__cap_empty_set
);
28 int file_caps_enabled
= 1;
30 static int __init
file_caps_disable(char *str
)
32 file_caps_enabled
= 0;
35 __setup("no_file_caps", file_caps_disable
);
38 * More recent versions of libcap are available from:
40 * http://www.kernel.org/pub/linux/libs/security/linux-privs/
43 static void warn_legacy_capability_use(void)
47 char name
[sizeof(current
->comm
)];
49 printk(KERN_INFO
"warning: `%s' uses 32-bit capabilities"
50 " (legacy support in use)\n",
51 get_task_comm(name
, current
));
57 * Version 2 capabilities worked fine, but the linux/capability.h file
58 * that accompanied their introduction encouraged their use without
59 * the necessary user-space source code changes. As such, we have
60 * created a version 3 with equivalent functionality to version 2, but
61 * with a header change to protect legacy source code from using
62 * version 2 when it wanted to use version 1. If your system has code
63 * that trips the following warning, it is using version 2 specific
64 * capabilities and may be doing so insecurely.
66 * The remedy is to either upgrade your version of libcap (to 2.10+,
67 * if the application is linked against it), or recompile your
68 * application with modern kernel headers and this warning will go
72 static void warn_deprecated_v2(void)
77 char name
[sizeof(current
->comm
)];
79 printk(KERN_INFO
"warning: `%s' uses deprecated v2"
80 " capabilities in a way that may be insecure.\n",
81 get_task_comm(name
, current
));
87 * Version check. Return the number of u32s in each capability flag
88 * array, or a negative value on error.
90 static int cap_validate_magic(cap_user_header_t header
, unsigned *tocopy
)
94 if (get_user(version
, &header
->version
))
98 case _LINUX_CAPABILITY_VERSION_1
:
99 warn_legacy_capability_use();
100 *tocopy
= _LINUX_CAPABILITY_U32S_1
;
102 case _LINUX_CAPABILITY_VERSION_2
:
103 warn_deprecated_v2();
105 * fall through - v3 is otherwise equivalent to v2.
107 case _LINUX_CAPABILITY_VERSION_3
:
108 *tocopy
= _LINUX_CAPABILITY_U32S_3
;
111 if (put_user((u32
)_KERNEL_CAPABILITY_VERSION
, &header
->version
))
120 * The only thing that can change the capabilities of the current
121 * process is the current process. As such, we can't be in this code
122 * at the same time as we are in the process of setting capabilities
123 * in this process. The net result is that we can limit our use of
124 * locks to when we are reading the caps of another process.
126 static inline int cap_get_target_pid(pid_t pid
, kernel_cap_t
*pEp
,
127 kernel_cap_t
*pIp
, kernel_cap_t
*pPp
)
131 if (pid
&& (pid
!= task_pid_vnr(current
))) {
132 struct task_struct
*target
;
136 target
= find_task_by_vpid(pid
);
140 ret
= security_capget(target
, pEp
, pIp
, pPp
);
144 ret
= security_capget(current
, pEp
, pIp
, pPp
);
150 * sys_capget - get the capabilities of a given process.
151 * @header: pointer to struct that contains capability version and
153 * @dataptr: pointer to struct that contains the effective, permitted,
154 * and inheritable capabilities that are returned
156 * Returns 0 on success and < 0 on error.
158 SYSCALL_DEFINE2(capget
, cap_user_header_t
, header
, cap_user_data_t
, dataptr
)
163 kernel_cap_t pE
, pI
, pP
;
165 ret
= cap_validate_magic(header
, &tocopy
);
166 if ((dataptr
== NULL
) || (ret
!= 0))
167 return ((dataptr
== NULL
) && (ret
== -EINVAL
)) ? 0 : ret
;
169 if (get_user(pid
, &header
->pid
))
175 ret
= cap_get_target_pid(pid
, &pE
, &pI
, &pP
);
177 struct __user_cap_data_struct kdata
[_KERNEL_CAPABILITY_U32S
];
180 for (i
= 0; i
< tocopy
; i
++) {
181 kdata
[i
].effective
= pE
.cap
[i
];
182 kdata
[i
].permitted
= pP
.cap
[i
];
183 kdata
[i
].inheritable
= pI
.cap
[i
];
187 * Note, in the case, tocopy < _KERNEL_CAPABILITY_U32S,
188 * we silently drop the upper capabilities here. This
189 * has the effect of making older libcap
190 * implementations implicitly drop upper capability
191 * bits when they perform a: capget/modify/capset
194 * This behavior is considered fail-safe
195 * behavior. Upgrading the application to a newer
196 * version of libcap will enable access to the newer
199 * An alternative would be to return an error here
200 * (-ERANGE), but that causes legacy applications to
201 * unexpectidly fail; the capget/modify/capset aborts
202 * before modification is attempted and the application
205 if (copy_to_user(dataptr
, kdata
, tocopy
206 * sizeof(struct __user_cap_data_struct
))) {
215 * sys_capset - set capabilities for a process or (*) a group of processes
216 * @header: pointer to struct that contains capability version and
218 * @data: pointer to struct that contains the effective, permitted,
219 * and inheritable capabilities
221 * Set capabilities for the current process only. The ability to any other
222 * process(es) has been deprecated and removed.
224 * The restrictions on setting capabilities are specified as:
226 * I: any raised capabilities must be a subset of the old permitted
227 * P: any raised capabilities must be a subset of the old permitted
228 * E: must be set to a subset of new permitted
230 * Returns 0 on success and < 0 on error.
232 SYSCALL_DEFINE2(capset
, cap_user_header_t
, header
, const cap_user_data_t
, data
)
234 struct __user_cap_data_struct kdata
[_KERNEL_CAPABILITY_U32S
];
235 unsigned i
, tocopy
, copybytes
;
236 kernel_cap_t inheritable
, permitted
, effective
;
241 ret
= cap_validate_magic(header
, &tocopy
);
245 if (get_user(pid
, &header
->pid
))
248 /* may only affect current now */
249 if (pid
!= 0 && pid
!= task_pid_vnr(current
))
252 copybytes
= tocopy
* sizeof(struct __user_cap_data_struct
);
253 if (copybytes
> sizeof(kdata
))
256 if (copy_from_user(&kdata
, data
, copybytes
))
259 for (i
= 0; i
< tocopy
; i
++) {
260 effective
.cap
[i
] = kdata
[i
].effective
;
261 permitted
.cap
[i
] = kdata
[i
].permitted
;
262 inheritable
.cap
[i
] = kdata
[i
].inheritable
;
264 while (i
< _KERNEL_CAPABILITY_U32S
) {
265 effective
.cap
[i
] = 0;
266 permitted
.cap
[i
] = 0;
267 inheritable
.cap
[i
] = 0;
271 new = prepare_creds();
275 ret
= security_capset(new, current_cred(),
276 &effective
, &inheritable
, &permitted
);
280 audit_log_capset(pid
, new, current_cred());
282 return commit_creds(new);
290 * has_ns_capability - Does a task have a capability in a specific user ns
291 * @t: The task in question
292 * @ns: target user namespace
293 * @cap: The capability to be tested for
295 * Return true if the specified task has the given superior capability
296 * currently in effect to the specified user namespace, false if not.
298 * Note that this does not set PF_SUPERPRIV on the task.
300 bool has_ns_capability(struct task_struct
*t
,
301 struct user_namespace
*ns
, int cap
)
306 ret
= security_capable(__task_cred(t
), ns
, cap
);
313 * has_capability - Does a task have a capability in init_user_ns
314 * @t: The task in question
315 * @cap: The capability to be tested for
317 * Return true if the specified task has the given superior capability
318 * currently in effect to the initial user namespace, false if not.
320 * Note that this does not set PF_SUPERPRIV on the task.
322 bool has_capability(struct task_struct
*t
, int cap
)
324 return has_ns_capability(t
, &init_user_ns
, cap
);
328 * has_ns_capability_noaudit - Does a task have a capability (unaudited)
329 * in a specific user ns.
330 * @t: The task in question
331 * @ns: target user namespace
332 * @cap: The capability to be tested for
334 * Return true if the specified task has the given superior capability
335 * currently in effect to the specified user namespace, false if not.
336 * Do not write an audit message for the check.
338 * Note that this does not set PF_SUPERPRIV on the task.
340 bool has_ns_capability_noaudit(struct task_struct
*t
,
341 struct user_namespace
*ns
, int cap
)
346 ret
= security_capable_noaudit(__task_cred(t
), ns
, cap
);
353 * has_capability_noaudit - Does a task have a capability (unaudited) in the
355 * @t: The task in question
356 * @cap: The capability to be tested for
358 * Return true if the specified task has the given superior capability
359 * currently in effect to init_user_ns, false if not. Don't write an
360 * audit message for the check.
362 * Note that this does not set PF_SUPERPRIV on the task.
364 bool has_capability_noaudit(struct task_struct
*t
, int cap
)
366 return has_ns_capability_noaudit(t
, &init_user_ns
, cap
);
370 * ns_capable - Determine if the current task has a superior capability in effect
371 * @ns: The usernamespace we want the capability in
372 * @cap: The capability to be tested for
374 * Return true if the current task has the given superior capability currently
375 * available for use, false if not.
377 * This sets PF_SUPERPRIV on the task if the capability is available on the
378 * assumption that it's about to be used.
380 bool ns_capable(struct user_namespace
*ns
, int cap
)
382 if (unlikely(!cap_valid(cap
))) {
383 printk(KERN_CRIT
"capable() called with invalid cap=%u\n", cap
);
387 if (security_capable(current_cred(), ns
, cap
) == 0) {
388 current
->flags
|= PF_SUPERPRIV
;
393 EXPORT_SYMBOL(ns_capable
);
396 * file_ns_capable - Determine if the file's opener had a capability in effect
397 * @file: The file we want to check
398 * @ns: The usernamespace we want the capability in
399 * @cap: The capability to be tested for
401 * Return true if task that opened the file had a capability in effect
402 * when the file was opened.
404 * This does not set PF_SUPERPRIV because the caller may not
405 * actually be privileged.
407 bool file_ns_capable(const struct file
*file
, struct user_namespace
*ns
, int cap
)
409 if (WARN_ON_ONCE(!cap_valid(cap
)))
412 if (security_capable(file
->f_cred
, ns
, cap
) == 0)
417 EXPORT_SYMBOL(file_ns_capable
);
420 * capable - Determine if the current task has a superior capability in effect
421 * @cap: The capability to be tested for
423 * Return true if the current task has the given superior capability currently
424 * available for use, false if not.
426 * This sets PF_SUPERPRIV on the task if the capability is available on the
427 * assumption that it's about to be used.
429 bool capable(int cap
)
431 return ns_capable(&init_user_ns
, cap
);
433 EXPORT_SYMBOL(capable
);
436 * capable_wrt_inode_uidgid - Check nsown_capable and uid and gid mapped
437 * @inode: The inode in question
438 * @cap: The capability in question
440 * Return true if the current task has the given capability targeted at
441 * its own user namespace and that the given inode's uid and gid are
442 * mapped into the current user namespace.
444 bool capable_wrt_inode_uidgid(const struct inode
*inode
, int cap
)
446 struct user_namespace
*ns
= current_user_ns();
448 return ns_capable(ns
, cap
) && kuid_has_mapping(ns
, inode
->i_uid
) &&
449 kgid_has_mapping(ns
, inode
->i_gid
);
451 EXPORT_SYMBOL(capable_wrt_inode_uidgid
);