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Linux/include/linux/capability.h

  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 
 21 extern int file_caps_enabled;
 22 
 23 typedef 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 */
 28 struct 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 
 38 struct file;
 39 struct inode;
 40 struct dentry;
 41 struct user_namespace;
 42 
 43 extern const kernel_cap_t __cap_empty_set;
 44 extern const kernel_cap_t __cap_init_eff_set;
 45 
 46 /*
 47  * Internal kernel functions only
 48  */
 49 
 50 #define CAP_FOR_EACH_U32(__capi)  \
 51         for (__capi = 0; __capi < _KERNEL_CAPABILITY_U32S; ++__capi)
 52 
 53 /*
 54  * CAP_FS_MASK and CAP_NFSD_MASKS:
 55  *
 56  * The fs mask is all the privileges that fsuid==0 historically meant.
 57  * At one time in the past, that included CAP_MKNOD and CAP_LINUX_IMMUTABLE.
 58  *
 59  * It has never meant setting security.* and trusted.* xattrs.
 60  *
 61  * We could also define fsmask as follows:
 62  *   1. CAP_FS_MASK is the privilege to bypass all fs-related DAC permissions
 63  *   2. The security.* and trusted.* xattrs are fs-related MAC permissions
 64  */
 65 
 66 # define CAP_FS_MASK_B0     (CAP_TO_MASK(CAP_CHOWN)             \
 67                             | CAP_TO_MASK(CAP_MKNOD)            \
 68                             | CAP_TO_MASK(CAP_DAC_OVERRIDE)     \
 69                             | CAP_TO_MASK(CAP_DAC_READ_SEARCH)  \
 70                             | CAP_TO_MASK(CAP_FOWNER)           \
 71                             | CAP_TO_MASK(CAP_FSETID))
 72 
 73 # define CAP_FS_MASK_B1     (CAP_TO_MASK(CAP_MAC_OVERRIDE))
 74 
 75 #if _KERNEL_CAPABILITY_U32S != 2
 76 # error Fix up hand-coded capability macro initializers
 77 #else /* HAND-CODED capability initializers */
 78 
 79 #define CAP_LAST_U32                    ((_KERNEL_CAPABILITY_U32S) - 1)
 80 #define CAP_LAST_U32_VALID_MASK         (CAP_TO_MASK(CAP_LAST_CAP + 1) -1)
 81 
 82 # define CAP_EMPTY_SET    ((kernel_cap_t){{ 0, 0 }})
 83 # define CAP_FULL_SET     ((kernel_cap_t){{ ~0, CAP_LAST_U32_VALID_MASK }})
 84 # define CAP_FS_SET       ((kernel_cap_t){{ CAP_FS_MASK_B0 \
 85                                     | CAP_TO_MASK(CAP_LINUX_IMMUTABLE), \
 86                                     CAP_FS_MASK_B1 } })
 87 # define CAP_NFSD_SET     ((kernel_cap_t){{ CAP_FS_MASK_B0 \
 88                                     | CAP_TO_MASK(CAP_SYS_RESOURCE), \
 89                                     CAP_FS_MASK_B1 } })
 90 
 91 #endif /* _KERNEL_CAPABILITY_U32S != 2 */
 92 
 93 # define cap_clear(c)         do { (c) = __cap_empty_set; } while (0)
 94 
 95 #define cap_raise(c, flag)  ((c).cap[CAP_TO_INDEX(flag)] |= CAP_TO_MASK(flag))
 96 #define cap_lower(c, flag)  ((c).cap[CAP_TO_INDEX(flag)] &= ~CAP_TO_MASK(flag))
 97 #define cap_raised(c, flag) ((c).cap[CAP_TO_INDEX(flag)] & CAP_TO_MASK(flag))
 98 
 99 #define CAP_BOP_ALL(c, a, b, OP)                                    \
100 do {                                                                \
101         unsigned __capi;                                            \
102         CAP_FOR_EACH_U32(__capi) {                                  \
103                 c.cap[__capi] = a.cap[__capi] OP b.cap[__capi];     \
104         }                                                           \
105 } while (0)
106 
107 #define CAP_UOP_ALL(c, a, OP)                                       \
108 do {                                                                \
109         unsigned __capi;                                            \
110         CAP_FOR_EACH_U32(__capi) {                                  \
111                 c.cap[__capi] = OP a.cap[__capi];                   \
112         }                                                           \
113 } while (0)
114 
115 static inline kernel_cap_t cap_combine(const kernel_cap_t a,
116                                        const kernel_cap_t b)
117 {
118         kernel_cap_t dest;
119         CAP_BOP_ALL(dest, a, b, |);
120         return dest;
121 }
122 
123 static inline kernel_cap_t cap_intersect(const kernel_cap_t a,
124                                          const kernel_cap_t b)
125 {
126         kernel_cap_t dest;
127         CAP_BOP_ALL(dest, a, b, &);
128         return dest;
129 }
130 
131 static inline kernel_cap_t cap_drop(const kernel_cap_t a,
132                                     const kernel_cap_t drop)
133 {
134         kernel_cap_t dest;
135         CAP_BOP_ALL(dest, a, drop, &~);
136         return dest;
137 }
138 
139 static inline kernel_cap_t cap_invert(const kernel_cap_t c)
140 {
141         kernel_cap_t dest;
142         CAP_UOP_ALL(dest, c, ~);
143         return dest;
144 }
145 
146 static inline bool cap_isclear(const kernel_cap_t a)
147 {
148         unsigned __capi;
149         CAP_FOR_EACH_U32(__capi) {
150                 if (a.cap[__capi] != 0)
151                         return false;
152         }
153         return true;
154 }
155 
156 /*
157  * Check if "a" is a subset of "set".
158  * return true if ALL of the capabilities in "a" are also in "set"
159  *      cap_issubset(0101, 1111) will return true
160  * return false if ANY of the capabilities in "a" are not in "set"
161  *      cap_issubset(1111, 0101) will return false
162  */
163 static inline bool cap_issubset(const kernel_cap_t a, const kernel_cap_t set)
164 {
165         kernel_cap_t dest;
166         dest = cap_drop(a, set);
167         return cap_isclear(dest);
168 }
169 
170 /* Used to decide between falling back on the old suser() or fsuser(). */
171 
172 static inline kernel_cap_t cap_drop_fs_set(const kernel_cap_t a)
173 {
174         const kernel_cap_t __cap_fs_set = CAP_FS_SET;
175         return cap_drop(a, __cap_fs_set);
176 }
177 
178 static inline kernel_cap_t cap_raise_fs_set(const kernel_cap_t a,
179                                             const kernel_cap_t permitted)
180 {
181         const kernel_cap_t __cap_fs_set = CAP_FS_SET;
182         return cap_combine(a,
183                            cap_intersect(permitted, __cap_fs_set));
184 }
185 
186 static inline kernel_cap_t cap_drop_nfsd_set(const kernel_cap_t a)
187 {
188         const kernel_cap_t __cap_fs_set = CAP_NFSD_SET;
189         return cap_drop(a, __cap_fs_set);
190 }
191 
192 static inline kernel_cap_t cap_raise_nfsd_set(const kernel_cap_t a,
193                                               const kernel_cap_t permitted)
194 {
195         const kernel_cap_t __cap_nfsd_set = CAP_NFSD_SET;
196         return cap_combine(a,
197                            cap_intersect(permitted, __cap_nfsd_set));
198 }
199 
200 #ifdef CONFIG_MULTIUSER
201 extern bool has_capability(struct task_struct *t, int cap);
202 extern bool has_ns_capability(struct task_struct *t,
203                               struct user_namespace *ns, int cap);
204 extern bool has_capability_noaudit(struct task_struct *t, int cap);
205 extern bool has_ns_capability_noaudit(struct task_struct *t,
206                                       struct user_namespace *ns, int cap);
207 extern bool capable(int cap);
208 extern bool ns_capable(struct user_namespace *ns, int cap);
209 #else
210 static inline bool has_capability(struct task_struct *t, int cap)
211 {
212         return true;
213 }
214 static inline bool has_ns_capability(struct task_struct *t,
215                               struct user_namespace *ns, int cap)
216 {
217         return true;
218 }
219 static inline bool has_capability_noaudit(struct task_struct *t, int cap)
220 {
221         return true;
222 }
223 static inline bool has_ns_capability_noaudit(struct task_struct *t,
224                                       struct user_namespace *ns, int cap)
225 {
226         return true;
227 }
228 static inline bool capable(int cap)
229 {
230         return true;
231 }
232 static inline bool ns_capable(struct user_namespace *ns, int cap)
233 {
234         return true;
235 }
236 #endif /* CONFIG_MULTIUSER */
237 extern bool capable_wrt_inode_uidgid(const struct inode *inode, int cap);
238 extern bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap);
239 
240 /* audit system wants to get cap info from files as well */
241 extern int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps);
242 
243 #endif /* !_LINUX_CAPABILITY_H */
244 

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