blob: 24b8ad9c7f764d5c723e9ad8bfafc4327fbbbd5f [file] [log] [blame]
James Morris3e1c2512009-10-20 13:48:33 +09001/* Common capabilities, needed by capability.o.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 *
3 * This program is free software; you can redistribute it and/or modify
4 * it under the terms of the GNU General Public License as published by
5 * the Free Software Foundation; either version 2 of the License, or
6 * (at your option) any later version.
7 *
8 */
9
Tejal Kudav8ffffaed2016-09-06 16:09:07 -070010/*
11 * Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
12 */
13
Randy.Dunlapc59ede72006-01-11 12:17:46 -080014#include <linux/capability.h>
Eric Paris3fc689e2008-11-11 21:48:18 +110015#include <linux/audit.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070016#include <linux/module.h>
17#include <linux/init.h>
18#include <linux/kernel.h>
Casey Schauflerb1d9e6b2015-05-02 15:11:42 -070019#include <linux/lsm_hooks.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#include <linux/file.h>
21#include <linux/mm.h>
22#include <linux/mman.h>
23#include <linux/pagemap.h>
24#include <linux/swap.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070025#include <linux/skbuff.h>
26#include <linux/netlink.h>
27#include <linux/ptrace.h>
28#include <linux/xattr.h>
29#include <linux/hugetlb.h>
Serge E. Hallynb5376772007-10-16 23:31:36 -070030#include <linux/mount.h>
Serge E. Hallynb460cbc2007-10-18 23:39:52 -070031#include <linux/sched.h>
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -070032#include <linux/prctl.h>
33#include <linux/securebits.h>
Serge E. Hallyn34867402011-03-23 16:43:17 -070034#include <linux/user_namespace.h>
Al Viro40401532012-02-13 03:58:52 +000035#include <linux/binfmts.h>
Jonghwan Choi51b79be2012-04-18 17:23:04 -040036#include <linux/personality.h>
Andrew Morgan72c2d582007-10-18 03:05:59 -070037
Chia-chi Yeh9a5e2c02009-06-19 07:15:05 +080038#ifdef CONFIG_ANDROID_PARANOID_NETWORK
39#include <linux/android_aid.h>
40#endif
41
Tejal Kudav8ffffaed2016-09-06 16:09:07 -070042u8 disable_android_paranoid_network;
43EXPORT_SYMBOL(disable_android_paranoid_network);
44
45static int __init disable_android_paranoid_network_feature(char *s)
46{
47 disable_android_paranoid_network = 1;
48
49 return 1;
50}
51
52__setup("disable_android_paranoid_network",
53 disable_android_paranoid_network_feature);
54
Serge E. Hallynb5f22a52009-04-02 18:47:14 -050055/*
56 * If a non-root user executes a setuid-root binary in
57 * !secure(SECURE_NOROOT) mode, then we raise capabilities.
58 * However if fE is also set, then the intent is for only
59 * the file capabilities to be applied, and the setuid-root
60 * bit is left on either to change the uid (plausible) or
61 * to get full privilege on a kernel without file capabilities
62 * support. So in that case we do not raise capabilities.
63 *
64 * Warn if that happens, once per boot.
65 */
David Howellsd7627462010-08-17 23:52:56 +010066static void warn_setuid_and_fcaps_mixed(const char *fname)
Serge E. Hallynb5f22a52009-04-02 18:47:14 -050067{
68 static int warned;
69 if (!warned) {
70 printk(KERN_INFO "warning: `%s' has both setuid-root and"
71 " effective capabilities. Therefore not raising all"
72 " capabilities.\n", fname);
73 warned = 1;
74 }
75}
76
David Howells1d045982008-11-14 10:39:24 +110077/**
78 * cap_capable - Determine whether a task has a particular effective capability
David Howells3699c532009-01-06 22:27:01 +000079 * @cred: The credentials to use
Serge E. Hallyn34867402011-03-23 16:43:17 -070080 * @ns: The user namespace in which we need the capability
David Howells1d045982008-11-14 10:39:24 +110081 * @cap: The capability to check for
82 * @audit: Whether to write an audit message or not
83 *
84 * Determine whether the nominated task has the specified capability amongst
85 * its effective set, returning 0 if it does, -ve if it does not.
86 *
David Howells3699c532009-01-06 22:27:01 +000087 * NOTE WELL: cap_has_capability() cannot be used like the kernel's capable()
88 * and has_capability() functions. That is, it has the reverse semantics:
89 * cap_has_capability() returns 0 when a task has a capability, but the
90 * kernel's capable() and has_capability() returns 1 for this case.
Andrew G. Morgana6dbb1e2008-01-21 17:18:30 -080091 */
Eric Paris6a9de492012-01-03 12:25:14 -050092int cap_capable(const struct cred *cred, struct user_namespace *targ_ns,
93 int cap, int audit)
Linus Torvalds1da177e2005-04-16 15:20:36 -070094{
Eric W. Biederman520d9ea2012-12-13 18:06:40 -080095 struct user_namespace *ns = targ_ns;
Serge E. Hallyn34867402011-03-23 16:43:17 -070096
Tushar Behera713d6852012-03-26 16:54:15 +053097#ifdef CONFIG_ANDROID_PARANOID_NETWORK
Tejal Kudav8ffffaed2016-09-06 16:09:07 -070098 if (!disable_android_paranoid_network) {
99 if (cap == CAP_NET_RAW && in_egroup_p(AID_NET_RAW))
100 return 0;
101 if (cap == CAP_NET_ADMIN && in_egroup_p(AID_NET_ADMIN))
102 return 0;
103 }
Tushar Behera713d6852012-03-26 16:54:15 +0530104#endif
Chia-chi Yeh9a5e2c02009-06-19 07:15:05 +0800105
Eric W. Biederman520d9ea2012-12-13 18:06:40 -0800106 /* See if cred has the capability in the target user namespace
107 * by examining the target user namespace and all of the target
108 * user namespace's parents.
109 */
110 for (;;) {
Serge E. Hallyn34867402011-03-23 16:43:17 -0700111 /* Do we have the necessary capabilities? */
Eric W. Biederman520d9ea2012-12-13 18:06:40 -0800112 if (ns == cred->user_ns)
Serge E. Hallyn34867402011-03-23 16:43:17 -0700113 return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM;
114
115 /* Have we tried all of the parent namespaces? */
Eric W. Biederman520d9ea2012-12-13 18:06:40 -0800116 if (ns == &init_user_ns)
Serge E. Hallyn34867402011-03-23 16:43:17 -0700117 return -EPERM;
118
Eric W. Biederman520d9ea2012-12-13 18:06:40 -0800119 /*
120 * The owner of the user namespace in the parent of the
121 * user namespace has all caps.
122 */
123 if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid))
124 return 0;
125
Serge E. Hallyn34867402011-03-23 16:43:17 -0700126 /*
Eric W. Biederman520d9ea2012-12-13 18:06:40 -0800127 * If you have a capability in a parent user ns, then you have
Serge E. Hallyn34867402011-03-23 16:43:17 -0700128 * it over all children user namespaces as well.
129 */
Eric W. Biederman520d9ea2012-12-13 18:06:40 -0800130 ns = ns->parent;
Serge E. Hallyn34867402011-03-23 16:43:17 -0700131 }
132
133 /* We never get here */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134}
135
David Howells1d045982008-11-14 10:39:24 +1100136/**
137 * cap_settime - Determine whether the current process may set the system clock
138 * @ts: The time to set
139 * @tz: The timezone to set
140 *
141 * Determine whether the current process may set the system clock and timezone
142 * information, returning 0 if permission granted, -ve if denied.
143 */
Richard Cochran1e6d7672011-02-01 13:50:58 +0000144int cap_settime(const struct timespec *ts, const struct timezone *tz)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145{
146 if (!capable(CAP_SYS_TIME))
147 return -EPERM;
148 return 0;
149}
150
David Howells1d045982008-11-14 10:39:24 +1100151/**
Ingo Molnar9e488582009-05-07 19:26:19 +1000152 * cap_ptrace_access_check - Determine whether the current process may access
David Howells1d045982008-11-14 10:39:24 +1100153 * another
154 * @child: The process to be accessed
155 * @mode: The mode of attachment.
156 *
Serge E. Hallyn8409cca2011-03-23 16:43:20 -0700157 * If we are in the same or an ancestor user_ns and have all the target
158 * task's capabilities, then ptrace access is allowed.
159 * If we have the ptrace capability to the target user_ns, then ptrace
160 * access is allowed.
161 * Else denied.
162 *
David Howells1d045982008-11-14 10:39:24 +1100163 * Determine whether a process may access another, returning 0 if permission
164 * granted, -ve if denied.
165 */
Ingo Molnar9e488582009-05-07 19:26:19 +1000166int cap_ptrace_access_check(struct task_struct *child, unsigned int mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167{
David Howellsc69e8d92008-11-14 10:39:19 +1100168 int ret = 0;
Serge E. Hallyn8409cca2011-03-23 16:43:20 -0700169 const struct cred *cred, *child_cred;
Jann Horn969624b2016-01-20 15:00:04 -0800170 const kernel_cap_t *caller_caps;
David Howellsc69e8d92008-11-14 10:39:19 +1100171
172 rcu_read_lock();
Serge E. Hallyn8409cca2011-03-23 16:43:20 -0700173 cred = current_cred();
174 child_cred = __task_cred(child);
Jann Horn969624b2016-01-20 15:00:04 -0800175 if (mode & PTRACE_MODE_FSCREDS)
176 caller_caps = &cred->cap_effective;
177 else
178 caller_caps = &cred->cap_permitted;
Eric W. Biedermanc4a4d602011-11-16 23:15:31 -0800179 if (cred->user_ns == child_cred->user_ns &&
Jann Horn969624b2016-01-20 15:00:04 -0800180 cap_issubset(child_cred->cap_permitted, *caller_caps))
Serge E. Hallyn8409cca2011-03-23 16:43:20 -0700181 goto out;
Eric W. Biedermanc4a4d602011-11-16 23:15:31 -0800182 if (ns_capable(child_cred->user_ns, CAP_SYS_PTRACE))
Serge E. Hallyn8409cca2011-03-23 16:43:20 -0700183 goto out;
184 ret = -EPERM;
185out:
David Howellsc69e8d92008-11-14 10:39:19 +1100186 rcu_read_unlock();
187 return ret;
David Howells5cd9c582008-08-14 11:37:28 +0100188}
189
David Howells1d045982008-11-14 10:39:24 +1100190/**
191 * cap_ptrace_traceme - Determine whether another process may trace the current
192 * @parent: The task proposed to be the tracer
193 *
Serge E. Hallyn8409cca2011-03-23 16:43:20 -0700194 * If parent is in the same or an ancestor user_ns and has all current's
195 * capabilities, then ptrace access is allowed.
196 * If parent has the ptrace capability to current's user_ns, then ptrace
197 * access is allowed.
198 * Else denied.
199 *
David Howells1d045982008-11-14 10:39:24 +1100200 * Determine whether the nominated task is permitted to trace the current
201 * process, returning 0 if permission is granted, -ve if denied.
202 */
David Howells5cd9c582008-08-14 11:37:28 +0100203int cap_ptrace_traceme(struct task_struct *parent)
204{
David Howellsc69e8d92008-11-14 10:39:19 +1100205 int ret = 0;
Serge E. Hallyn8409cca2011-03-23 16:43:20 -0700206 const struct cred *cred, *child_cred;
David Howellsc69e8d92008-11-14 10:39:19 +1100207
208 rcu_read_lock();
Serge E. Hallyn8409cca2011-03-23 16:43:20 -0700209 cred = __task_cred(parent);
210 child_cred = current_cred();
Eric W. Biedermanc4a4d602011-11-16 23:15:31 -0800211 if (cred->user_ns == child_cred->user_ns &&
Serge E. Hallyn8409cca2011-03-23 16:43:20 -0700212 cap_issubset(child_cred->cap_permitted, cred->cap_permitted))
213 goto out;
Eric W. Biedermanc4a4d602011-11-16 23:15:31 -0800214 if (has_ns_capability(parent, child_cred->user_ns, CAP_SYS_PTRACE))
Serge E. Hallyn8409cca2011-03-23 16:43:20 -0700215 goto out;
216 ret = -EPERM;
217out:
David Howellsc69e8d92008-11-14 10:39:19 +1100218 rcu_read_unlock();
219 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220}
221
David Howells1d045982008-11-14 10:39:24 +1100222/**
223 * cap_capget - Retrieve a task's capability sets
224 * @target: The task from which to retrieve the capability sets
225 * @effective: The place to record the effective set
226 * @inheritable: The place to record the inheritable set
227 * @permitted: The place to record the permitted set
228 *
229 * This function retrieves the capabilities of the nominated task and returns
230 * them to the caller.
231 */
232int cap_capget(struct task_struct *target, kernel_cap_t *effective,
233 kernel_cap_t *inheritable, kernel_cap_t *permitted)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234{
David Howellsc69e8d92008-11-14 10:39:19 +1100235 const struct cred *cred;
David Howellsb6dff3e2008-11-14 10:39:16 +1100236
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237 /* Derived from kernel/capability.c:sys_capget. */
David Howellsc69e8d92008-11-14 10:39:19 +1100238 rcu_read_lock();
239 cred = __task_cred(target);
David Howellsb6dff3e2008-11-14 10:39:16 +1100240 *effective = cred->cap_effective;
241 *inheritable = cred->cap_inheritable;
242 *permitted = cred->cap_permitted;
David Howellsc69e8d92008-11-14 10:39:19 +1100243 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244 return 0;
245}
246
David Howells1d045982008-11-14 10:39:24 +1100247/*
248 * Determine whether the inheritable capabilities are limited to the old
249 * permitted set. Returns 1 if they are limited, 0 if they are not.
250 */
Andrew Morgan72c2d582007-10-18 03:05:59 -0700251static inline int cap_inh_is_capped(void)
252{
David Howells1d045982008-11-14 10:39:24 +1100253
254 /* they are so limited unless the current task has the CAP_SETPCAP
255 * capability
Andrew Morgan72c2d582007-10-18 03:05:59 -0700256 */
Eric W. Biedermanc4a4d602011-11-16 23:15:31 -0800257 if (cap_capable(current_cred(), current_cred()->user_ns,
Eric Paris6a9de492012-01-03 12:25:14 -0500258 CAP_SETPCAP, SECURITY_CAP_AUDIT) == 0)
David Howells1d045982008-11-14 10:39:24 +1100259 return 0;
David Howells1d045982008-11-14 10:39:24 +1100260 return 1;
Andrew Morgan72c2d582007-10-18 03:05:59 -0700261}
262
David Howells1d045982008-11-14 10:39:24 +1100263/**
264 * cap_capset - Validate and apply proposed changes to current's capabilities
265 * @new: The proposed new credentials; alterations should be made here
266 * @old: The current task's current credentials
267 * @effective: A pointer to the proposed new effective capabilities set
268 * @inheritable: A pointer to the proposed new inheritable capabilities set
269 * @permitted: A pointer to the proposed new permitted capabilities set
270 *
271 * This function validates and applies a proposed mass change to the current
272 * process's capability sets. The changes are made to the proposed new
273 * credentials, and assuming no error, will be committed by the caller of LSM.
274 */
David Howellsd84f4f92008-11-14 10:39:23 +1100275int cap_capset(struct cred *new,
276 const struct cred *old,
277 const kernel_cap_t *effective,
278 const kernel_cap_t *inheritable,
279 const kernel_cap_t *permitted)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280{
David Howellsd84f4f92008-11-14 10:39:23 +1100281 if (cap_inh_is_capped() &&
282 !cap_issubset(*inheritable,
283 cap_combine(old->cap_inheritable,
284 old->cap_permitted)))
Andrew Morgan72c2d582007-10-18 03:05:59 -0700285 /* incapable of using this inheritable set */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286 return -EPERM;
David Howellsd84f4f92008-11-14 10:39:23 +1100287
Serge E. Hallyn3b7391d2008-02-04 22:29:45 -0800288 if (!cap_issubset(*inheritable,
David Howellsd84f4f92008-11-14 10:39:23 +1100289 cap_combine(old->cap_inheritable,
290 old->cap_bset)))
Serge E. Hallyn3b7391d2008-02-04 22:29:45 -0800291 /* no new pI capabilities outside bounding set */
292 return -EPERM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293
294 /* verify restrictions on target's new Permitted set */
David Howellsd84f4f92008-11-14 10:39:23 +1100295 if (!cap_issubset(*permitted, old->cap_permitted))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 return -EPERM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297
298 /* verify the _new_Effective_ is a subset of the _new_Permitted_ */
David Howellsd84f4f92008-11-14 10:39:23 +1100299 if (!cap_issubset(*effective, *permitted))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300 return -EPERM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301
David Howellsd84f4f92008-11-14 10:39:23 +1100302 new->cap_effective = *effective;
303 new->cap_inheritable = *inheritable;
304 new->cap_permitted = *permitted;
Andy Lutomirski58319052015-09-04 15:42:45 -0700305
306 /*
307 * Mask off ambient bits that are no longer both permitted and
308 * inheritable.
309 */
310 new->cap_ambient = cap_intersect(new->cap_ambient,
311 cap_intersect(*permitted,
312 *inheritable));
313 if (WARN_ON(!cap_ambient_invariant_ok(new)))
314 return -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700315 return 0;
316}
317
David Howells1d045982008-11-14 10:39:24 +1100318/*
319 * Clear proposed capability sets for execve().
320 */
Serge E. Hallynb5376772007-10-16 23:31:36 -0700321static inline void bprm_clear_caps(struct linux_binprm *bprm)
322{
David Howellsa6f76f22008-11-14 10:39:24 +1100323 cap_clear(bprm->cred->cap_permitted);
Serge E. Hallynb5376772007-10-16 23:31:36 -0700324 bprm->cap_effective = false;
325}
326
David Howells1d045982008-11-14 10:39:24 +1100327/**
328 * cap_inode_need_killpriv - Determine if inode change affects privileges
329 * @dentry: The inode/dentry in being changed with change marked ATTR_KILL_PRIV
330 *
331 * Determine if an inode having a change applied that's marked ATTR_KILL_PRIV
332 * affects the security markings on that inode, and if it is, should
333 * inode_killpriv() be invoked or the change rejected?
334 *
335 * Returns 0 if granted; +ve if granted, but inode_killpriv() is required; and
336 * -ve to deny the change.
337 */
Serge E. Hallynb5376772007-10-16 23:31:36 -0700338int cap_inode_need_killpriv(struct dentry *dentry)
339{
David Howellsc6f493d2015-03-17 22:26:22 +0000340 struct inode *inode = d_backing_inode(dentry);
Serge E. Hallynb5376772007-10-16 23:31:36 -0700341 int error;
342
Al Viroacfa4382008-12-04 10:06:33 -0500343 if (!inode->i_op->getxattr)
Serge E. Hallynb5376772007-10-16 23:31:36 -0700344 return 0;
345
346 error = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, NULL, 0);
347 if (error <= 0)
348 return 0;
349 return 1;
350}
351
David Howells1d045982008-11-14 10:39:24 +1100352/**
353 * cap_inode_killpriv - Erase the security markings on an inode
354 * @dentry: The inode/dentry to alter
355 *
356 * Erase the privilege-enhancing security markings on an inode.
357 *
358 * Returns 0 if successful, -ve on error.
359 */
Serge E. Hallynb5376772007-10-16 23:31:36 -0700360int cap_inode_killpriv(struct dentry *dentry)
361{
David Howellsc6f493d2015-03-17 22:26:22 +0000362 struct inode *inode = d_backing_inode(dentry);
Serge E. Hallynb5376772007-10-16 23:31:36 -0700363
Al Viroacfa4382008-12-04 10:06:33 -0500364 if (!inode->i_op->removexattr)
Serge E. Hallynb5376772007-10-16 23:31:36 -0700365 return 0;
366
367 return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS);
368}
369
David Howells1d045982008-11-14 10:39:24 +1100370/*
371 * Calculate the new process capability sets from the capability sets attached
372 * to a file.
373 */
Eric Parisc0b00442008-11-11 21:48:10 +1100374static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps,
David Howellsa6f76f22008-11-14 10:39:24 +1100375 struct linux_binprm *bprm,
Zhi Li4d49f672011-08-11 13:27:50 +0800376 bool *effective,
377 bool *has_cap)
Serge E. Hallynb5376772007-10-16 23:31:36 -0700378{
David Howellsa6f76f22008-11-14 10:39:24 +1100379 struct cred *new = bprm->cred;
Eric Parisc0b00442008-11-11 21:48:10 +1100380 unsigned i;
381 int ret = 0;
382
383 if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE)
David Howellsa6f76f22008-11-14 10:39:24 +1100384 *effective = true;
Eric Parisc0b00442008-11-11 21:48:10 +1100385
Zhi Li4d49f672011-08-11 13:27:50 +0800386 if (caps->magic_etc & VFS_CAP_REVISION_MASK)
387 *has_cap = true;
388
Eric Parisc0b00442008-11-11 21:48:10 +1100389 CAP_FOR_EACH_U32(i) {
390 __u32 permitted = caps->permitted.cap[i];
391 __u32 inheritable = caps->inheritable.cap[i];
392
393 /*
394 * pP' = (X & fP) | (pI & fI)
Andy Lutomirski58319052015-09-04 15:42:45 -0700395 * The addition of pA' is handled later.
Eric Parisc0b00442008-11-11 21:48:10 +1100396 */
David Howellsa6f76f22008-11-14 10:39:24 +1100397 new->cap_permitted.cap[i] =
398 (new->cap_bset.cap[i] & permitted) |
399 (new->cap_inheritable.cap[i] & inheritable);
Eric Parisc0b00442008-11-11 21:48:10 +1100400
David Howellsa6f76f22008-11-14 10:39:24 +1100401 if (permitted & ~new->cap_permitted.cap[i])
402 /* insufficient to execute correctly */
Eric Parisc0b00442008-11-11 21:48:10 +1100403 ret = -EPERM;
Eric Parisc0b00442008-11-11 21:48:10 +1100404 }
405
406 /*
407 * For legacy apps, with no internal support for recognizing they
408 * do not have enough capabilities, we return an error if they are
409 * missing some "forced" (aka file-permitted) capabilities.
410 */
David Howellsa6f76f22008-11-14 10:39:24 +1100411 return *effective ? ret : 0;
Eric Parisc0b00442008-11-11 21:48:10 +1100412}
413
David Howells1d045982008-11-14 10:39:24 +1100414/*
415 * Extract the on-exec-apply capability sets for an executable file.
416 */
Eric Parisc0b00442008-11-11 21:48:10 +1100417int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps)
418{
David Howellsc6f493d2015-03-17 22:26:22 +0000419 struct inode *inode = d_backing_inode(dentry);
Serge E. Hallynb5376772007-10-16 23:31:36 -0700420 __u32 magic_etc;
Andrew Morgane338d262008-02-04 22:29:42 -0800421 unsigned tocopy, i;
Eric Parisc0b00442008-11-11 21:48:10 +1100422 int size;
423 struct vfs_cap_data caps;
424
425 memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data));
426
Al Viroacfa4382008-12-04 10:06:33 -0500427 if (!inode || !inode->i_op->getxattr)
Eric Parisc0b00442008-11-11 21:48:10 +1100428 return -ENODATA;
429
430 size = inode->i_op->getxattr((struct dentry *)dentry, XATTR_NAME_CAPS, &caps,
431 XATTR_CAPS_SZ);
David Howellsa6f76f22008-11-14 10:39:24 +1100432 if (size == -ENODATA || size == -EOPNOTSUPP)
Eric Parisc0b00442008-11-11 21:48:10 +1100433 /* no data, that's ok */
434 return -ENODATA;
Eric Parisc0b00442008-11-11 21:48:10 +1100435 if (size < 0)
436 return size;
Serge E. Hallynb5376772007-10-16 23:31:36 -0700437
Andrew Morgane338d262008-02-04 22:29:42 -0800438 if (size < sizeof(magic_etc))
Serge E. Hallynb5376772007-10-16 23:31:36 -0700439 return -EINVAL;
440
Eric Parisc0b00442008-11-11 21:48:10 +1100441 cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps.magic_etc);
Serge E. Hallynb5376772007-10-16 23:31:36 -0700442
David Howellsa6f76f22008-11-14 10:39:24 +1100443 switch (magic_etc & VFS_CAP_REVISION_MASK) {
Andrew Morgane338d262008-02-04 22:29:42 -0800444 case VFS_CAP_REVISION_1:
445 if (size != XATTR_CAPS_SZ_1)
446 return -EINVAL;
447 tocopy = VFS_CAP_U32_1;
448 break;
449 case VFS_CAP_REVISION_2:
450 if (size != XATTR_CAPS_SZ_2)
451 return -EINVAL;
452 tocopy = VFS_CAP_U32_2;
453 break;
Serge E. Hallynb5376772007-10-16 23:31:36 -0700454 default:
455 return -EINVAL;
456 }
Andrew Morgane338d262008-02-04 22:29:42 -0800457
Andrew G. Morgan5459c162008-07-23 21:28:24 -0700458 CAP_FOR_EACH_U32(i) {
Eric Parisc0b00442008-11-11 21:48:10 +1100459 if (i >= tocopy)
460 break;
461 cpu_caps->permitted.cap[i] = le32_to_cpu(caps.data[i].permitted);
462 cpu_caps->inheritable.cap[i] = le32_to_cpu(caps.data[i].inheritable);
Andrew Morgane338d262008-02-04 22:29:42 -0800463 }
David Howellsa6f76f22008-11-14 10:39:24 +1100464
Eric Paris7d8b6c62014-07-23 15:36:26 -0400465 cpu_caps->permitted.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
466 cpu_caps->inheritable.cap[CAP_LAST_U32] &= CAP_LAST_U32_VALID_MASK;
467
Eric Parisc0b00442008-11-11 21:48:10 +1100468 return 0;
Serge E. Hallynb5376772007-10-16 23:31:36 -0700469}
470
David Howells1d045982008-11-14 10:39:24 +1100471/*
472 * Attempt to get the on-exec apply capability sets for an executable file from
473 * its xattrs and, if present, apply them to the proposed credentials being
474 * constructed by execve().
475 */
Zhi Li4d49f672011-08-11 13:27:50 +0800476static int get_file_caps(struct linux_binprm *bprm, bool *effective, bool *has_cap)
Serge E. Hallynb5376772007-10-16 23:31:36 -0700477{
Serge E. Hallynb5376772007-10-16 23:31:36 -0700478 int rc = 0;
Eric Parisc0b00442008-11-11 21:48:10 +1100479 struct cpu_vfs_cap_data vcaps;
Serge E. Hallynb5376772007-10-16 23:31:36 -0700480
Serge Hallyn3318a382008-10-30 11:52:23 -0500481 bprm_clear_caps(bprm);
482
Serge E. Hallyn1f29fae2008-11-05 16:08:52 -0600483 if (!file_caps_enabled)
484 return 0;
485
Al Viro182be682013-01-24 02:21:54 -0500486 if (bprm->file->f_path.mnt->mnt_flags & MNT_NOSUID)
Serge E. Hallynb5376772007-10-16 23:31:36 -0700487 return 0;
Serge E. Hallynb5376772007-10-16 23:31:36 -0700488
Al Virof4a4a8b2014-12-28 09:27:07 -0500489 rc = get_vfs_caps_from_disk(bprm->file->f_path.dentry, &vcaps);
Eric Parisc0b00442008-11-11 21:48:10 +1100490 if (rc < 0) {
491 if (rc == -EINVAL)
492 printk(KERN_NOTICE "%s: get_vfs_caps_from_disk returned %d for %s\n",
493 __func__, rc, bprm->filename);
494 else if (rc == -ENODATA)
495 rc = 0;
Serge E. Hallynb5376772007-10-16 23:31:36 -0700496 goto out;
497 }
Serge E. Hallynb5376772007-10-16 23:31:36 -0700498
Zhi Li4d49f672011-08-11 13:27:50 +0800499 rc = bprm_caps_from_vfs_caps(&vcaps, bprm, effective, has_cap);
David Howellsa6f76f22008-11-14 10:39:24 +1100500 if (rc == -EINVAL)
501 printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n",
502 __func__, rc, bprm->filename);
Serge E. Hallynb5376772007-10-16 23:31:36 -0700503
504out:
Serge E. Hallynb5376772007-10-16 23:31:36 -0700505 if (rc)
506 bprm_clear_caps(bprm);
507
508 return rc;
509}
510
David Howells1d045982008-11-14 10:39:24 +1100511/**
512 * cap_bprm_set_creds - Set up the proposed credentials for execve().
513 * @bprm: The execution parameters, including the proposed creds
514 *
515 * Set up the proposed credentials for a new execution context being
516 * constructed by execve(). The proposed creds in @bprm->cred is altered,
517 * which won't take effect immediately. Returns 0 if successful, -ve on error.
David Howellsa6f76f22008-11-14 10:39:24 +1100518 */
519int cap_bprm_set_creds(struct linux_binprm *bprm)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700520{
David Howellsa6f76f22008-11-14 10:39:24 +1100521 const struct cred *old = current_cred();
522 struct cred *new = bprm->cred;
Andy Lutomirski58319052015-09-04 15:42:45 -0700523 bool effective, has_cap = false, is_setid;
Serge E. Hallynb5376772007-10-16 23:31:36 -0700524 int ret;
Eric W. Biederman18815a12012-02-07 16:45:47 -0800525 kuid_t root_uid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526
Andy Lutomirski58319052015-09-04 15:42:45 -0700527 if (WARN_ON(!cap_ambient_invariant_ok(old)))
528 return -EPERM;
529
David Howellsa6f76f22008-11-14 10:39:24 +1100530 effective = false;
Zhi Li4d49f672011-08-11 13:27:50 +0800531 ret = get_file_caps(bprm, &effective, &has_cap);
David Howellsa6f76f22008-11-14 10:39:24 +1100532 if (ret < 0)
533 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700534
Eric W. Biederman18815a12012-02-07 16:45:47 -0800535 root_uid = make_kuid(new->user_ns, 0);
536
Andrew G. Morgan5459c162008-07-23 21:28:24 -0700537 if (!issecure(SECURE_NOROOT)) {
538 /*
Serge E. Hallynb5f22a52009-04-02 18:47:14 -0500539 * If the legacy file capability is set, then don't set privs
540 * for a setuid root binary run by a non-root user. Do set it
541 * for a root user just to cause least surprise to an admin.
542 */
Eric W. Biederman18815a12012-02-07 16:45:47 -0800543 if (has_cap && !uid_eq(new->uid, root_uid) && uid_eq(new->euid, root_uid)) {
Serge E. Hallynb5f22a52009-04-02 18:47:14 -0500544 warn_setuid_and_fcaps_mixed(bprm->filename);
545 goto skip;
546 }
547 /*
Andrew G. Morgan5459c162008-07-23 21:28:24 -0700548 * To support inheritance of root-permissions and suid-root
549 * executables under compatibility mode, we override the
550 * capability sets for the file.
551 *
David Howellsa6f76f22008-11-14 10:39:24 +1100552 * If only the real uid is 0, we do not set the effective bit.
Andrew G. Morgan5459c162008-07-23 21:28:24 -0700553 */
Eric W. Biederman18815a12012-02-07 16:45:47 -0800554 if (uid_eq(new->euid, root_uid) || uid_eq(new->uid, root_uid)) {
Andrew G. Morgan5459c162008-07-23 21:28:24 -0700555 /* pP' = (cap_bset & ~0) | (pI & ~0) */
David Howellsa6f76f22008-11-14 10:39:24 +1100556 new->cap_permitted = cap_combine(old->cap_bset,
557 old->cap_inheritable);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700558 }
Eric W. Biederman18815a12012-02-07 16:45:47 -0800559 if (uid_eq(new->euid, root_uid))
David Howellsa6f76f22008-11-14 10:39:24 +1100560 effective = true;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700561 }
Serge E. Hallynb5f22a52009-04-02 18:47:14 -0500562skip:
Serge E. Hallynb5376772007-10-16 23:31:36 -0700563
Eric Parisd52fc5d2012-04-17 16:26:54 -0400564 /* if we have fs caps, clear dangerous personality flags */
565 if (!cap_issubset(new->cap_permitted, old->cap_permitted))
566 bprm->per_clear |= PER_CLEAR_ON_SETID;
567
568
David Howellsa6f76f22008-11-14 10:39:24 +1100569 /* Don't let someone trace a set[ug]id/setpcap binary with the revised
Andy Lutomirski259e5e62012-04-12 16:47:50 -0500570 * credentials unless they have the appropriate permit.
571 *
572 * In addition, if NO_NEW_PRIVS, then ensure we get no new privs.
David Howellsa6f76f22008-11-14 10:39:24 +1100573 */
Andy Lutomirski58319052015-09-04 15:42:45 -0700574 is_setid = !uid_eq(new->euid, old->uid) || !gid_eq(new->egid, old->gid);
575
576 if ((is_setid ||
David Howellsa6f76f22008-11-14 10:39:24 +1100577 !cap_issubset(new->cap_permitted, old->cap_permitted)) &&
578 bprm->unsafe & ~LSM_UNSAFE_PTRACE_CAP) {
579 /* downgrade; they get no more than they had, and maybe less */
Andy Lutomirski259e5e62012-04-12 16:47:50 -0500580 if (!capable(CAP_SETUID) ||
581 (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)) {
David Howellsa6f76f22008-11-14 10:39:24 +1100582 new->euid = new->uid;
583 new->egid = new->gid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584 }
Serge E. Hallynb3a222e2009-11-23 16:21:30 -0600585 new->cap_permitted = cap_intersect(new->cap_permitted,
586 old->cap_permitted);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700587 }
588
David Howellsa6f76f22008-11-14 10:39:24 +1100589 new->suid = new->fsuid = new->euid;
590 new->sgid = new->fsgid = new->egid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591
Andy Lutomirski58319052015-09-04 15:42:45 -0700592 /* File caps or setid cancels ambient. */
593 if (has_cap || is_setid)
594 cap_clear(new->cap_ambient);
595
596 /*
597 * Now that we've computed pA', update pP' to give:
598 * pP' = (X & fP) | (pI & fI) | pA'
599 */
600 new->cap_permitted = cap_combine(new->cap_permitted, new->cap_ambient);
601
602 /*
603 * Set pE' = (fE ? pP' : pA'). Because pA' is zero if fE is set,
604 * this is the same as pE' = (fE ? pP' : 0) | pA'.
605 */
Eric Paris4bf2ea72011-04-01 17:08:28 -0400606 if (effective)
607 new->cap_effective = new->cap_permitted;
608 else
Andy Lutomirski58319052015-09-04 15:42:45 -0700609 new->cap_effective = new->cap_ambient;
610
611 if (WARN_ON(!cap_ambient_invariant_ok(new)))
612 return -EPERM;
613
David Howellsa6f76f22008-11-14 10:39:24 +1100614 bprm->cap_effective = effective;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615
Eric Paris3fc689e2008-11-11 21:48:18 +1100616 /*
617 * Audit candidate if current->cap_effective is set
618 *
619 * We do not bother to audit if 3 things are true:
620 * 1) cap_effective has all caps
621 * 2) we are root
622 * 3) root is supposed to have all caps (SECURE_NOROOT)
623 * Since this is just a normal root execing a process.
624 *
625 * Number 1 above might fail if you don't have a full bset, but I think
626 * that is interesting information to audit.
627 */
Andy Lutomirski58319052015-09-04 15:42:45 -0700628 if (!cap_issubset(new->cap_effective, new->cap_ambient)) {
David Howellsd84f4f92008-11-14 10:39:23 +1100629 if (!cap_issubset(CAP_FULL_SET, new->cap_effective) ||
Eric W. Biederman18815a12012-02-07 16:45:47 -0800630 !uid_eq(new->euid, root_uid) || !uid_eq(new->uid, root_uid) ||
David Howellsa6f76f22008-11-14 10:39:24 +1100631 issecure(SECURE_NOROOT)) {
632 ret = audit_log_bprm_fcaps(bprm, new, old);
633 if (ret < 0)
634 return ret;
635 }
Eric Paris3fc689e2008-11-11 21:48:18 +1100636 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637
David Howellsd84f4f92008-11-14 10:39:23 +1100638 new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
Andy Lutomirski58319052015-09-04 15:42:45 -0700639
640 if (WARN_ON(!cap_ambient_invariant_ok(new)))
641 return -EPERM;
642
David Howellsa6f76f22008-11-14 10:39:24 +1100643 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700644}
645
David Howells1d045982008-11-14 10:39:24 +1100646/**
647 * cap_bprm_secureexec - Determine whether a secure execution is required
648 * @bprm: The execution parameters
649 *
650 * Determine whether a secure execution is required, return 1 if it is, and 0
651 * if it is not.
652 *
653 * The credentials have been committed by this point, and so are no longer
654 * available through @bprm->cred.
David Howellsa6f76f22008-11-14 10:39:24 +1100655 */
656int cap_bprm_secureexec(struct linux_binprm *bprm)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700657{
David Howellsc69e8d92008-11-14 10:39:19 +1100658 const struct cred *cred = current_cred();
Eric W. Biederman18815a12012-02-07 16:45:47 -0800659 kuid_t root_uid = make_kuid(cred->user_ns, 0);
David Howellsb6dff3e2008-11-14 10:39:16 +1100660
Eric W. Biederman18815a12012-02-07 16:45:47 -0800661 if (!uid_eq(cred->uid, root_uid)) {
Serge E. Hallynb5376772007-10-16 23:31:36 -0700662 if (bprm->cap_effective)
663 return 1;
Andy Lutomirski58319052015-09-04 15:42:45 -0700664 if (!cap_issubset(cred->cap_permitted, cred->cap_ambient))
Serge E. Hallynb5376772007-10-16 23:31:36 -0700665 return 1;
666 }
667
Eric W. Biederman18815a12012-02-07 16:45:47 -0800668 return (!uid_eq(cred->euid, cred->uid) ||
669 !gid_eq(cred->egid, cred->gid));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700670}
671
David Howells1d045982008-11-14 10:39:24 +1100672/**
673 * cap_inode_setxattr - Determine whether an xattr may be altered
674 * @dentry: The inode/dentry being altered
675 * @name: The name of the xattr to be changed
676 * @value: The value that the xattr will be changed to
677 * @size: The size of value
678 * @flags: The replacement flag
679 *
680 * Determine whether an xattr may be altered or set on an inode, returning 0 if
681 * permission is granted, -ve if denied.
682 *
683 * This is used to make sure security xattrs don't get updated or set by those
684 * who aren't privileged to do so.
685 */
David Howells8f0cfa52008-04-29 00:59:41 -0700686int cap_inode_setxattr(struct dentry *dentry, const char *name,
687 const void *value, size_t size, int flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688{
Serge E. Hallynb5376772007-10-16 23:31:36 -0700689 if (!strcmp(name, XATTR_NAME_CAPS)) {
690 if (!capable(CAP_SETFCAP))
691 return -EPERM;
692 return 0;
David Howells1d045982008-11-14 10:39:24 +1100693 }
694
695 if (!strncmp(name, XATTR_SECURITY_PREFIX,
Justin P. Mattockc5b60b52010-04-21 00:02:11 -0700696 sizeof(XATTR_SECURITY_PREFIX) - 1) &&
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697 !capable(CAP_SYS_ADMIN))
698 return -EPERM;
699 return 0;
700}
701
David Howells1d045982008-11-14 10:39:24 +1100702/**
703 * cap_inode_removexattr - Determine whether an xattr may be removed
704 * @dentry: The inode/dentry being altered
705 * @name: The name of the xattr to be changed
706 *
707 * Determine whether an xattr may be removed from an inode, returning 0 if
708 * permission is granted, -ve if denied.
709 *
710 * This is used to make sure security xattrs don't get removed by those who
711 * aren't privileged to remove them.
712 */
David Howells8f0cfa52008-04-29 00:59:41 -0700713int cap_inode_removexattr(struct dentry *dentry, const char *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700714{
Serge E. Hallynb5376772007-10-16 23:31:36 -0700715 if (!strcmp(name, XATTR_NAME_CAPS)) {
716 if (!capable(CAP_SETFCAP))
717 return -EPERM;
718 return 0;
David Howells1d045982008-11-14 10:39:24 +1100719 }
720
721 if (!strncmp(name, XATTR_SECURITY_PREFIX,
Justin P. Mattockc5b60b52010-04-21 00:02:11 -0700722 sizeof(XATTR_SECURITY_PREFIX) - 1) &&
Linus Torvalds1da177e2005-04-16 15:20:36 -0700723 !capable(CAP_SYS_ADMIN))
724 return -EPERM;
725 return 0;
726}
727
David Howellsa6f76f22008-11-14 10:39:24 +1100728/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729 * cap_emulate_setxuid() fixes the effective / permitted capabilities of
730 * a process after a call to setuid, setreuid, or setresuid.
731 *
732 * 1) When set*uiding _from_ one of {r,e,s}uid == 0 _to_ all of
733 * {r,e,s}uid != 0, the permitted and effective capabilities are
734 * cleared.
735 *
736 * 2) When set*uiding _from_ euid == 0 _to_ euid != 0, the effective
737 * capabilities of the process are cleared.
738 *
739 * 3) When set*uiding _from_ euid != 0 _to_ euid == 0, the effective
740 * capabilities are set to the permitted capabilities.
741 *
David Howellsa6f76f22008-11-14 10:39:24 +1100742 * fsuid is handled elsewhere. fsuid == 0 and {r,e,s}uid!= 0 should
Linus Torvalds1da177e2005-04-16 15:20:36 -0700743 * never happen.
744 *
David Howellsa6f76f22008-11-14 10:39:24 +1100745 * -astor
Linus Torvalds1da177e2005-04-16 15:20:36 -0700746 *
747 * cevans - New behaviour, Oct '99
748 * A process may, via prctl(), elect to keep its capabilities when it
749 * calls setuid() and switches away from uid==0. Both permitted and
750 * effective sets will be retained.
751 * Without this change, it was impossible for a daemon to drop only some
752 * of its privilege. The call to setuid(!=0) would drop all privileges!
753 * Keeping uid 0 is not an option because uid 0 owns too many vital
754 * files..
755 * Thanks to Olaf Kirch and Peter Benie for spotting this.
756 */
David Howellsd84f4f92008-11-14 10:39:23 +1100757static inline void cap_emulate_setxuid(struct cred *new, const struct cred *old)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700758{
Eric W. Biederman18815a12012-02-07 16:45:47 -0800759 kuid_t root_uid = make_kuid(old->user_ns, 0);
760
761 if ((uid_eq(old->uid, root_uid) ||
762 uid_eq(old->euid, root_uid) ||
763 uid_eq(old->suid, root_uid)) &&
764 (!uid_eq(new->uid, root_uid) &&
765 !uid_eq(new->euid, root_uid) &&
Andy Lutomirski58319052015-09-04 15:42:45 -0700766 !uid_eq(new->suid, root_uid))) {
767 if (!issecure(SECURE_KEEP_CAPS)) {
768 cap_clear(new->cap_permitted);
769 cap_clear(new->cap_effective);
770 }
771
772 /*
773 * Pre-ambient programs expect setresuid to nonroot followed
774 * by exec to drop capabilities. We should make sure that
775 * this remains the case.
776 */
777 cap_clear(new->cap_ambient);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700778 }
Eric W. Biederman18815a12012-02-07 16:45:47 -0800779 if (uid_eq(old->euid, root_uid) && !uid_eq(new->euid, root_uid))
David Howellsd84f4f92008-11-14 10:39:23 +1100780 cap_clear(new->cap_effective);
Eric W. Biederman18815a12012-02-07 16:45:47 -0800781 if (!uid_eq(old->euid, root_uid) && uid_eq(new->euid, root_uid))
David Howellsd84f4f92008-11-14 10:39:23 +1100782 new->cap_effective = new->cap_permitted;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700783}
784
David Howells1d045982008-11-14 10:39:24 +1100785/**
786 * cap_task_fix_setuid - Fix up the results of setuid() call
787 * @new: The proposed credentials
788 * @old: The current task's current credentials
789 * @flags: Indications of what has changed
790 *
791 * Fix up the results of setuid() call before the credential changes are
792 * actually applied, returning 0 to grant the changes, -ve to deny them.
793 */
David Howellsd84f4f92008-11-14 10:39:23 +1100794int cap_task_fix_setuid(struct cred *new, const struct cred *old, int flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700795{
796 switch (flags) {
797 case LSM_SETID_RE:
798 case LSM_SETID_ID:
799 case LSM_SETID_RES:
David Howells1d045982008-11-14 10:39:24 +1100800 /* juggle the capabilities to follow [RES]UID changes unless
801 * otherwise suppressed */
David Howellsd84f4f92008-11-14 10:39:23 +1100802 if (!issecure(SECURE_NO_SETUID_FIXUP))
803 cap_emulate_setxuid(new, old);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700805
David Howells1d045982008-11-14 10:39:24 +1100806 case LSM_SETID_FS:
807 /* juggle the capabilties to follow FSUID changes, unless
808 * otherwise suppressed
809 *
David Howellsd84f4f92008-11-14 10:39:23 +1100810 * FIXME - is fsuser used for all CAP_FS_MASK capabilities?
811 * if not, we might be a bit too harsh here.
812 */
813 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
Eric W. Biederman18815a12012-02-07 16:45:47 -0800814 kuid_t root_uid = make_kuid(old->user_ns, 0);
815 if (uid_eq(old->fsuid, root_uid) && !uid_eq(new->fsuid, root_uid))
David Howellsd84f4f92008-11-14 10:39:23 +1100816 new->cap_effective =
817 cap_drop_fs_set(new->cap_effective);
David Howells1d045982008-11-14 10:39:24 +1100818
Eric W. Biederman18815a12012-02-07 16:45:47 -0800819 if (!uid_eq(old->fsuid, root_uid) && uid_eq(new->fsuid, root_uid))
David Howellsd84f4f92008-11-14 10:39:23 +1100820 new->cap_effective =
821 cap_raise_fs_set(new->cap_effective,
822 new->cap_permitted);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700823 }
David Howellsd84f4f92008-11-14 10:39:23 +1100824 break;
David Howells1d045982008-11-14 10:39:24 +1100825
Linus Torvalds1da177e2005-04-16 15:20:36 -0700826 default:
827 return -EINVAL;
828 }
829
830 return 0;
831}
832
Serge E. Hallynb5376772007-10-16 23:31:36 -0700833/*
834 * Rationale: code calling task_setscheduler, task_setioprio, and
835 * task_setnice, assumes that
836 * . if capable(cap_sys_nice), then those actions should be allowed
837 * . if not capable(cap_sys_nice), but acting on your own processes,
838 * then those actions should be allowed
839 * This is insufficient now since you can call code without suid, but
840 * yet with increased caps.
841 * So we check for increased caps on the target process.
842 */
Serge E. Hallynde45e802008-09-26 22:27:47 -0400843static int cap_safe_nice(struct task_struct *p)
Serge E. Hallynb5376772007-10-16 23:31:36 -0700844{
Serge Hallynf54fb862013-07-23 13:18:53 -0500845 int is_subset, ret = 0;
David Howellsc69e8d92008-11-14 10:39:19 +1100846
847 rcu_read_lock();
848 is_subset = cap_issubset(__task_cred(p)->cap_permitted,
849 current_cred()->cap_permitted);
Serge Hallynf54fb862013-07-23 13:18:53 -0500850 if (!is_subset && !ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE))
851 ret = -EPERM;
David Howellsc69e8d92008-11-14 10:39:19 +1100852 rcu_read_unlock();
853
Serge Hallynf54fb862013-07-23 13:18:53 -0500854 return ret;
Serge E. Hallynb5376772007-10-16 23:31:36 -0700855}
856
David Howells1d045982008-11-14 10:39:24 +1100857/**
858 * cap_task_setscheduler - Detemine if scheduler policy change is permitted
859 * @p: The task to affect
David Howells1d045982008-11-14 10:39:24 +1100860 *
861 * Detemine if the requested scheduler policy change is permitted for the
862 * specified task, returning 0 if permission is granted, -ve if denied.
863 */
KOSAKI Motohirob0ae1982010-10-15 04:21:18 +0900864int cap_task_setscheduler(struct task_struct *p)
Serge E. Hallynb5376772007-10-16 23:31:36 -0700865{
866 return cap_safe_nice(p);
867}
868
David Howells1d045982008-11-14 10:39:24 +1100869/**
870 * cap_task_ioprio - Detemine if I/O priority change is permitted
871 * @p: The task to affect
872 * @ioprio: The I/O priority to set
873 *
874 * Detemine if the requested I/O priority change is permitted for the specified
875 * task, returning 0 if permission is granted, -ve if denied.
876 */
877int cap_task_setioprio(struct task_struct *p, int ioprio)
Serge E. Hallynb5376772007-10-16 23:31:36 -0700878{
879 return cap_safe_nice(p);
880}
881
David Howells1d045982008-11-14 10:39:24 +1100882/**
883 * cap_task_ioprio - Detemine if task priority change is permitted
884 * @p: The task to affect
885 * @nice: The nice value to set
886 *
887 * Detemine if the requested task priority change is permitted for the
888 * specified task, returning 0 if permission is granted, -ve if denied.
889 */
890int cap_task_setnice(struct task_struct *p, int nice)
Serge E. Hallynb5376772007-10-16 23:31:36 -0700891{
892 return cap_safe_nice(p);
893}
894
Serge E. Hallyn3b7391d2008-02-04 22:29:45 -0800895/*
David Howells1d045982008-11-14 10:39:24 +1100896 * Implement PR_CAPBSET_DROP. Attempt to remove the specified capability from
897 * the current task's bounding set. Returns 0 on success, -ve on error.
Serge E. Hallyn3b7391d2008-02-04 22:29:45 -0800898 */
Tetsuo Handa6d6f3322014-07-22 21:20:01 +0900899static int cap_prctl_drop(unsigned long cap)
Serge E. Hallyn3b7391d2008-02-04 22:29:45 -0800900{
Tetsuo Handa6d6f3322014-07-22 21:20:01 +0900901 struct cred *new;
902
Eric W. Biederman160da842013-07-02 10:04:54 -0700903 if (!ns_capable(current_user_ns(), CAP_SETPCAP))
Serge E. Hallyn3b7391d2008-02-04 22:29:45 -0800904 return -EPERM;
905 if (!cap_valid(cap))
906 return -EINVAL;
David Howellsd84f4f92008-11-14 10:39:23 +1100907
Tetsuo Handa6d6f3322014-07-22 21:20:01 +0900908 new = prepare_creds();
909 if (!new)
910 return -ENOMEM;
David Howellsd84f4f92008-11-14 10:39:23 +1100911 cap_lower(new->cap_bset, cap);
Tetsuo Handa6d6f3322014-07-22 21:20:01 +0900912 return commit_creds(new);
Serge E. Hallyn3b7391d2008-02-04 22:29:45 -0800913}
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -0700914
David Howells1d045982008-11-14 10:39:24 +1100915/**
916 * cap_task_prctl - Implement process control functions for this security module
917 * @option: The process control function requested
918 * @arg2, @arg3, @arg4, @arg5: The argument data for this function
919 *
920 * Allow process control functions (sys_prctl()) to alter capabilities; may
921 * also deny access to other functions not otherwise implemented here.
922 *
923 * Returns 0 or +ve on success, -ENOSYS if this function is not implemented
924 * here, other -ve on error. If -ENOSYS is returned, sys_prctl() and other LSM
925 * modules will consider performing the function.
926 */
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -0700927int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
David Howellsd84f4f92008-11-14 10:39:23 +1100928 unsigned long arg4, unsigned long arg5)
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -0700929{
Tetsuo Handa6d6f3322014-07-22 21:20:01 +0900930 const struct cred *old = current_cred();
David Howellsd84f4f92008-11-14 10:39:23 +1100931 struct cred *new;
David Howellsd84f4f92008-11-14 10:39:23 +1100932
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -0700933 switch (option) {
934 case PR_CAPBSET_READ:
935 if (!cap_valid(arg2))
Tetsuo Handa6d6f3322014-07-22 21:20:01 +0900936 return -EINVAL;
937 return !!cap_raised(old->cap_bset, arg2);
David Howellsd84f4f92008-11-14 10:39:23 +1100938
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -0700939 case PR_CAPBSET_DROP:
Tetsuo Handa6d6f3322014-07-22 21:20:01 +0900940 return cap_prctl_drop(arg2);
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -0700941
942 /*
943 * The next four prctl's remain to assist with transitioning a
944 * system from legacy UID=0 based privilege (when filesystem
945 * capabilities are not in use) to a system using filesystem
946 * capabilities only - as the POSIX.1e draft intended.
947 *
948 * Note:
949 *
950 * PR_SET_SECUREBITS =
951 * issecure_mask(SECURE_KEEP_CAPS_LOCKED)
952 * | issecure_mask(SECURE_NOROOT)
953 * | issecure_mask(SECURE_NOROOT_LOCKED)
954 * | issecure_mask(SECURE_NO_SETUID_FIXUP)
955 * | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED)
956 *
957 * will ensure that the current process and all of its
958 * children will be locked into a pure
959 * capability-based-privilege environment.
960 */
961 case PR_SET_SECUREBITS:
Tetsuo Handa6d6f3322014-07-22 21:20:01 +0900962 if ((((old->securebits & SECURE_ALL_LOCKS) >> 1)
963 & (old->securebits ^ arg2)) /*[1]*/
964 || ((old->securebits & SECURE_ALL_LOCKS & ~arg2)) /*[2]*/
David Howellsd84f4f92008-11-14 10:39:23 +1100965 || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/
Eric Paris6a9de492012-01-03 12:25:14 -0500966 || (cap_capable(current_cred(),
Eric W. Biedermanc4a4d602011-11-16 23:15:31 -0800967 current_cred()->user_ns, CAP_SETPCAP,
David Howells3699c532009-01-06 22:27:01 +0000968 SECURITY_CAP_AUDIT) != 0) /*[4]*/
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -0700969 /*
970 * [1] no changing of bits that are locked
971 * [2] no unlocking of locks
972 * [3] no setting of unsupported bits
973 * [4] doing anything requires privilege (go read about
974 * the "sendmail capabilities bug")
975 */
David Howellsd84f4f92008-11-14 10:39:23 +1100976 )
977 /* cannot change a locked bit */
Tetsuo Handa6d6f3322014-07-22 21:20:01 +0900978 return -EPERM;
979
980 new = prepare_creds();
981 if (!new)
982 return -ENOMEM;
David Howellsd84f4f92008-11-14 10:39:23 +1100983 new->securebits = arg2;
Tetsuo Handa6d6f3322014-07-22 21:20:01 +0900984 return commit_creds(new);
David Howellsd84f4f92008-11-14 10:39:23 +1100985
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -0700986 case PR_GET_SECUREBITS:
Tetsuo Handa6d6f3322014-07-22 21:20:01 +0900987 return old->securebits;
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -0700988
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -0700989 case PR_GET_KEEPCAPS:
Tetsuo Handa6d6f3322014-07-22 21:20:01 +0900990 return !!issecure(SECURE_KEEP_CAPS);
David Howellsd84f4f92008-11-14 10:39:23 +1100991
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -0700992 case PR_SET_KEEPCAPS:
993 if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */
Tetsuo Handa6d6f3322014-07-22 21:20:01 +0900994 return -EINVAL;
David Howellsd84f4f92008-11-14 10:39:23 +1100995 if (issecure(SECURE_KEEP_CAPS_LOCKED))
Tetsuo Handa6d6f3322014-07-22 21:20:01 +0900996 return -EPERM;
997
998 new = prepare_creds();
999 if (!new)
1000 return -ENOMEM;
David Howellsd84f4f92008-11-14 10:39:23 +11001001 if (arg2)
1002 new->securebits |= issecure_mask(SECURE_KEEP_CAPS);
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -07001003 else
David Howellsd84f4f92008-11-14 10:39:23 +11001004 new->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
Tetsuo Handa6d6f3322014-07-22 21:20:01 +09001005 return commit_creds(new);
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -07001006
Andy Lutomirski58319052015-09-04 15:42:45 -07001007 case PR_CAP_AMBIENT:
1008 if (arg2 == PR_CAP_AMBIENT_CLEAR_ALL) {
1009 if (arg3 | arg4 | arg5)
1010 return -EINVAL;
1011
1012 new = prepare_creds();
1013 if (!new)
1014 return -ENOMEM;
1015 cap_clear(new->cap_ambient);
1016 return commit_creds(new);
1017 }
1018
1019 if (((!cap_valid(arg3)) | arg4 | arg5))
1020 return -EINVAL;
1021
1022 if (arg2 == PR_CAP_AMBIENT_IS_SET) {
1023 return !!cap_raised(current_cred()->cap_ambient, arg3);
1024 } else if (arg2 != PR_CAP_AMBIENT_RAISE &&
1025 arg2 != PR_CAP_AMBIENT_LOWER) {
1026 return -EINVAL;
1027 } else {
1028 if (arg2 == PR_CAP_AMBIENT_RAISE &&
1029 (!cap_raised(current_cred()->cap_permitted, arg3) ||
1030 !cap_raised(current_cred()->cap_inheritable,
Andy Lutomirski746bf6d2015-09-04 15:42:51 -07001031 arg3) ||
1032 issecure(SECURE_NO_CAP_AMBIENT_RAISE)))
Andy Lutomirski58319052015-09-04 15:42:45 -07001033 return -EPERM;
1034
1035 new = prepare_creds();
1036 if (!new)
1037 return -ENOMEM;
1038 if (arg2 == PR_CAP_AMBIENT_RAISE)
1039 cap_raise(new->cap_ambient, arg3);
1040 else
1041 cap_lower(new->cap_ambient, arg3);
1042 return commit_creds(new);
1043 }
1044
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -07001045 default:
1046 /* No functionality available - continue with default */
Tetsuo Handa6d6f3322014-07-22 21:20:01 +09001047 return -ENOSYS;
Andrew G. Morgan3898b1b2008-04-28 02:13:40 -07001048 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001049}
1050
David Howells1d045982008-11-14 10:39:24 +11001051/**
David Howells1d045982008-11-14 10:39:24 +11001052 * cap_vm_enough_memory - Determine whether a new virtual mapping is permitted
1053 * @mm: The VM space in which the new mapping is to be made
1054 * @pages: The size of the mapping
1055 *
1056 * Determine whether the allocation of a new virtual mapping by the current
Casey Schauflerb1d9e6b2015-05-02 15:11:42 -07001057 * task is permitted, returning 1 if permission is granted, 0 if not.
David Howells1d045982008-11-14 10:39:24 +11001058 */
Alan Cox34b4e4a2007-08-22 14:01:28 -07001059int cap_vm_enough_memory(struct mm_struct *mm, long pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001060{
1061 int cap_sys_admin = 0;
1062
Eric Paris6a9de492012-01-03 12:25:14 -05001063 if (cap_capable(current_cred(), &init_user_ns, CAP_SYS_ADMIN,
David Howells3699c532009-01-06 22:27:01 +00001064 SECURITY_CAP_NOAUDIT) == 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001065 cap_sys_admin = 1;
Casey Schauflerb1d9e6b2015-05-02 15:11:42 -07001066 return cap_sys_admin;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001067}
Eric Paris7c738752009-07-31 12:53:58 -04001068
1069/*
Al Virod0077942012-05-30 13:11:37 -04001070 * cap_mmap_addr - check if able to map given addr
1071 * @addr: address attempting to be mapped
1072 *
1073 * If the process is attempting to map memory below dac_mmap_min_addr they need
1074 * CAP_SYS_RAWIO. The other parameters to this function are unused by the
1075 * capability security module. Returns 0 if this mapping should be allowed
1076 * -EPERM if not.
1077 */
1078int cap_mmap_addr(unsigned long addr)
1079{
1080 int ret = 0;
1081
1082 if (addr < dac_mmap_min_addr) {
1083 ret = cap_capable(current_cred(), &init_user_ns, CAP_SYS_RAWIO,
1084 SECURITY_CAP_AUDIT);
1085 /* set PF_SUPERPRIV if it turns out we allow the low mmap */
1086 if (ret == 0)
1087 current->flags |= PF_SUPERPRIV;
1088 }
1089 return ret;
1090}
1091
Al Viroe5467852012-05-30 13:30:51 -04001092int cap_mmap_file(struct file *file, unsigned long reqprot,
1093 unsigned long prot, unsigned long flags)
Eric Paris7c738752009-07-31 12:53:58 -04001094{
Al Viroe5467852012-05-30 13:30:51 -04001095 return 0;
Eric Paris7c738752009-07-31 12:53:58 -04001096}
Casey Schauflerb1d9e6b2015-05-02 15:11:42 -07001097
1098#ifdef CONFIG_SECURITY
1099
1100struct security_hook_list capability_hooks[] = {
1101 LSM_HOOK_INIT(capable, cap_capable),
1102 LSM_HOOK_INIT(settime, cap_settime),
1103 LSM_HOOK_INIT(ptrace_access_check, cap_ptrace_access_check),
1104 LSM_HOOK_INIT(ptrace_traceme, cap_ptrace_traceme),
1105 LSM_HOOK_INIT(capget, cap_capget),
1106 LSM_HOOK_INIT(capset, cap_capset),
1107 LSM_HOOK_INIT(bprm_set_creds, cap_bprm_set_creds),
1108 LSM_HOOK_INIT(bprm_secureexec, cap_bprm_secureexec),
1109 LSM_HOOK_INIT(inode_need_killpriv, cap_inode_need_killpriv),
1110 LSM_HOOK_INIT(inode_killpriv, cap_inode_killpriv),
1111 LSM_HOOK_INIT(mmap_addr, cap_mmap_addr),
1112 LSM_HOOK_INIT(mmap_file, cap_mmap_file),
1113 LSM_HOOK_INIT(task_fix_setuid, cap_task_fix_setuid),
1114 LSM_HOOK_INIT(task_prctl, cap_task_prctl),
1115 LSM_HOOK_INIT(task_setscheduler, cap_task_setscheduler),
1116 LSM_HOOK_INIT(task_setioprio, cap_task_setioprio),
1117 LSM_HOOK_INIT(task_setnice, cap_task_setnice),
1118 LSM_HOOK_INIT(vm_enough_memory, cap_vm_enough_memory),
1119};
1120
1121void __init capability_add_hooks(void)
1122{
1123 security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks));
1124}
1125
1126#endif /* CONFIG_SECURITY */