1/*
2 * This is <linux/capability.h>
3 *
4 * Andrew G. Morgan <morgan@kernel.org>
5 * Alexander Kjeldaas <astor@guardian.no>
6 * with help from Aleph1, Roland Buresund and Andrew Main.
7 *
8 * See here for the libcap library ("POSIX draft" compliance):
9 *
10 * ftp://www.kernel.org/pub/linux/libs/security/linux-privs/kernel-2.6/
11 */
12#ifndef _LINUX_CAPABILITY_H
13#define _LINUX_CAPABILITY_H
14
15#include <uapi/linux/capability.h>
16
17
18#define _KERNEL_CAPABILITY_VERSION _LINUX_CAPABILITY_VERSION_3
19#define _KERNEL_CAPABILITY_U32S    _LINUX_CAPABILITY_U32S_3
20
21extern int file_caps_enabled;
22
23typedef struct kernel_cap_struct {
24	__u32 cap[_KERNEL_CAPABILITY_U32S];
25} kernel_cap_t;
26
27/* exact same as vfs_cap_data but in cpu endian and always filled completely */
28struct cpu_vfs_cap_data {
29	__u32 magic_etc;
30	kernel_cap_t permitted;
31	kernel_cap_t inheritable;
32};
33
34#define _USER_CAP_HEADER_SIZE  (sizeof(struct __user_cap_header_struct))
35#define _KERNEL_CAP_T_SIZE     (sizeof(kernel_cap_t))
36
37
38struct file;
39struct inode;
40struct dentry;
41struct user_namespace;
42
43struct user_namespace *current_user_ns(void);
44
45extern const kernel_cap_t __cap_empty_set;
46extern const kernel_cap_t __cap_init_eff_set;
47
48/*
49 * Internal kernel functions only
50 */
51
52#define CAP_FOR_EACH_U32(__capi)  \
53	for (__capi = 0; __capi < _KERNEL_CAPABILITY_U32S; ++__capi)
54
55/*
56 * CAP_FS_MASK and CAP_NFSD_MASKS:
57 *
58 * The fs mask is all the privileges that fsuid==0 historically meant.
59 * At one time in the past, that included CAP_MKNOD and CAP_LINUX_IMMUTABLE.
60 *
61 * It has never meant setting security.* and trusted.* xattrs.
62 *
63 * We could also define fsmask as follows:
64 *   1. CAP_FS_MASK is the privilege to bypass all fs-related DAC permissions
65 *   2. The security.* and trusted.* xattrs are fs-related MAC permissions
66 */
67
68# define CAP_FS_MASK_B0     (CAP_TO_MASK(CAP_CHOWN)		\
69			    | CAP_TO_MASK(CAP_MKNOD)		\
70			    | CAP_TO_MASK(CAP_DAC_OVERRIDE)	\
71			    | CAP_TO_MASK(CAP_DAC_READ_SEARCH)	\
72			    | CAP_TO_MASK(CAP_FOWNER)		\
73			    | CAP_TO_MASK(CAP_FSETID))
74
75# define CAP_FS_MASK_B1     (CAP_TO_MASK(CAP_MAC_OVERRIDE))
76
77#if _KERNEL_CAPABILITY_U32S != 2
78# error Fix up hand-coded capability macro initializers
79#else /* HAND-CODED capability initializers */
80
81#define CAP_LAST_U32			((_KERNEL_CAPABILITY_U32S) - 1)
82#define CAP_LAST_U32_VALID_MASK		(CAP_TO_MASK(CAP_LAST_CAP + 1) -1)
83
84# define CAP_EMPTY_SET    ((kernel_cap_t){{ 0, 0 }})
85# define CAP_FULL_SET     ((kernel_cap_t){{ ~0, CAP_LAST_U32_VALID_MASK }})
86# define CAP_FS_SET       ((kernel_cap_t){{ CAP_FS_MASK_B0 \
87				    | CAP_TO_MASK(CAP_LINUX_IMMUTABLE), \
88				    CAP_FS_MASK_B1 } })
89# define CAP_NFSD_SET     ((kernel_cap_t){{ CAP_FS_MASK_B0 \
90				    | CAP_TO_MASK(CAP_SYS_RESOURCE), \
91				    CAP_FS_MASK_B1 } })
92
93#endif /* _KERNEL_CAPABILITY_U32S != 2 */
94
95# define cap_clear(c)         do { (c) = __cap_empty_set; } while (0)
96
97#define cap_raise(c, flag)  ((c).cap[CAP_TO_INDEX(flag)] |= CAP_TO_MASK(flag))
98#define cap_lower(c, flag)  ((c).cap[CAP_TO_INDEX(flag)] &= ~CAP_TO_MASK(flag))
99#define cap_raised(c, flag) ((c).cap[CAP_TO_INDEX(flag)] & CAP_TO_MASK(flag))
100
101#define CAP_BOP_ALL(c, a, b, OP)                                    \
102do {                                                                \
103	unsigned __capi;                                            \
104	CAP_FOR_EACH_U32(__capi) {                                  \
105		c.cap[__capi] = a.cap[__capi] OP b.cap[__capi];     \
106	}                                                           \
107} while (0)
108
109#define CAP_UOP_ALL(c, a, OP)                                       \
110do {                                                                \
111	unsigned __capi;                                            \
112	CAP_FOR_EACH_U32(__capi) {                                  \
113		c.cap[__capi] = OP a.cap[__capi];                   \
114	}                                                           \
115} while (0)
116
117static inline kernel_cap_t cap_combine(const kernel_cap_t a,
118				       const kernel_cap_t b)
119{
120	kernel_cap_t dest;
121	CAP_BOP_ALL(dest, a, b, |);
122	return dest;
123}
124
125static inline kernel_cap_t cap_intersect(const kernel_cap_t a,
126					 const kernel_cap_t b)
127{
128	kernel_cap_t dest;
129	CAP_BOP_ALL(dest, a, b, &);
130	return dest;
131}
132
133static inline kernel_cap_t cap_drop(const kernel_cap_t a,
134				    const kernel_cap_t drop)
135{
136	kernel_cap_t dest;
137	CAP_BOP_ALL(dest, a, drop, &~);
138	return dest;
139}
140
141static inline kernel_cap_t cap_invert(const kernel_cap_t c)
142{
143	kernel_cap_t dest;
144	CAP_UOP_ALL(dest, c, ~);
145	return dest;
146}
147
148static inline int cap_isclear(const kernel_cap_t a)
149{
150	unsigned __capi;
151	CAP_FOR_EACH_U32(__capi) {
152		if (a.cap[__capi] != 0)
153			return 0;
154	}
155	return 1;
156}
157
158/*
159 * Check if "a" is a subset of "set".
160 * return 1 if ALL of the capabilities in "a" are also in "set"
161 *	cap_issubset(0101, 1111) will return 1
162 * return 0 if ANY of the capabilities in "a" are not in "set"
163 *	cap_issubset(1111, 0101) will return 0
164 */
165static inline int cap_issubset(const kernel_cap_t a, const kernel_cap_t set)
166{
167	kernel_cap_t dest;
168	dest = cap_drop(a, set);
169	return cap_isclear(dest);
170}
171
172/* Used to decide between falling back on the old suser() or fsuser(). */
173
174static inline int cap_is_fs_cap(int cap)
175{
176	const kernel_cap_t __cap_fs_set = CAP_FS_SET;
177	return !!(CAP_TO_MASK(cap) & __cap_fs_set.cap[CAP_TO_INDEX(cap)]);
178}
179
180static inline kernel_cap_t cap_drop_fs_set(const kernel_cap_t a)
181{
182	const kernel_cap_t __cap_fs_set = CAP_FS_SET;
183	return cap_drop(a, __cap_fs_set);
184}
185
186static inline kernel_cap_t cap_raise_fs_set(const kernel_cap_t a,
187					    const kernel_cap_t permitted)
188{
189	const kernel_cap_t __cap_fs_set = CAP_FS_SET;
190	return cap_combine(a,
191			   cap_intersect(permitted, __cap_fs_set));
192}
193
194static inline kernel_cap_t cap_drop_nfsd_set(const kernel_cap_t a)
195{
196	const kernel_cap_t __cap_fs_set = CAP_NFSD_SET;
197	return cap_drop(a, __cap_fs_set);
198}
199
200static inline kernel_cap_t cap_raise_nfsd_set(const kernel_cap_t a,
201					      const kernel_cap_t permitted)
202{
203	const kernel_cap_t __cap_nfsd_set = CAP_NFSD_SET;
204	return cap_combine(a,
205			   cap_intersect(permitted, __cap_nfsd_set));
206}
207
208#ifdef CONFIG_MULTIUSER
209extern bool has_capability(struct task_struct *t, int cap);
210extern bool has_ns_capability(struct task_struct *t,
211			      struct user_namespace *ns, int cap);
212extern bool has_capability_noaudit(struct task_struct *t, int cap);
213extern bool has_ns_capability_noaudit(struct task_struct *t,
214				      struct user_namespace *ns, int cap);
215extern bool capable(int cap);
216extern bool ns_capable(struct user_namespace *ns, int cap);
217#else
218static inline bool has_capability(struct task_struct *t, int cap)
219{
220	return true;
221}
222static inline bool has_ns_capability(struct task_struct *t,
223			      struct user_namespace *ns, int cap)
224{
225	return true;
226}
227static inline bool has_capability_noaudit(struct task_struct *t, int cap)
228{
229	return true;
230}
231static inline bool has_ns_capability_noaudit(struct task_struct *t,
232				      struct user_namespace *ns, int cap)
233{
234	return true;
235}
236static inline bool capable(int cap)
237{
238	return true;
239}
240static inline bool ns_capable(struct user_namespace *ns, int cap)
241{
242	return true;
243}
244#endif /* CONFIG_MULTIUSER */
245extern bool capable_wrt_inode_uidgid(const struct inode *inode, int cap);
246extern bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap);
247
248/* audit system wants to get cap info from files as well */
249extern int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps);
250
251#endif /* !_LINUX_CAPABILITY_H */
252