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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 struct user_namespace *current_user_ns(void);
 44 
 45 extern const kernel_cap_t __cap_empty_set;
 46 extern 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_EMPTY_SET    ((kernel_cap_t){{ 0, 0 }})
 82 # define CAP_FULL_SET     ((kernel_cap_t){{ ~0, ~0 }})
 83 # define CAP_FS_SET       ((kernel_cap_t){{ CAP_FS_MASK_B0 \
 84                                     | CAP_TO_MASK(CAP_LINUX_IMMUTABLE), \
 85                                     CAP_FS_MASK_B1 } })
 86 # define CAP_NFSD_SET     ((kernel_cap_t){{ CAP_FS_MASK_B0 \
 87                                     | CAP_TO_MASK(CAP_SYS_RESOURCE), \
 88                                     CAP_FS_MASK_B1 } })
 89 
 90 #endif /* _KERNEL_CAPABILITY_U32S != 2 */
 91 
 92 # define cap_clear(c)         do { (c) = __cap_empty_set; } while (0)
 93 
 94 #define cap_raise(c, flag)  ((c).cap[CAP_TO_INDEX(flag)] |= CAP_TO_MASK(flag))
 95 #define cap_lower(c, flag)  ((c).cap[CAP_TO_INDEX(flag)] &= ~CAP_TO_MASK(flag))
 96 #define cap_raised(c, flag) ((c).cap[CAP_TO_INDEX(flag)] & CAP_TO_MASK(flag))
 97 
 98 #define CAP_BOP_ALL(c, a, b, OP)                                    \
 99 do {                                                                \
100         unsigned __capi;                                            \
101         CAP_FOR_EACH_U32(__capi) {                                  \
102                 c.cap[__capi] = a.cap[__capi] OP b.cap[__capi];     \
103         }                                                           \
104 } while (0)
105 
106 #define CAP_UOP_ALL(c, a, OP)                                       \
107 do {                                                                \
108         unsigned __capi;                                            \
109         CAP_FOR_EACH_U32(__capi) {                                  \
110                 c.cap[__capi] = OP a.cap[__capi];                   \
111         }                                                           \
112 } while (0)
113 
114 static inline kernel_cap_t cap_combine(const kernel_cap_t a,
115                                        const kernel_cap_t b)
116 {
117         kernel_cap_t dest;
118         CAP_BOP_ALL(dest, a, b, |);
119         return dest;
120 }
121 
122 static inline kernel_cap_t cap_intersect(const kernel_cap_t a,
123                                          const kernel_cap_t b)
124 {
125         kernel_cap_t dest;
126         CAP_BOP_ALL(dest, a, b, &);
127         return dest;
128 }
129 
130 static inline kernel_cap_t cap_drop(const kernel_cap_t a,
131                                     const kernel_cap_t drop)
132 {
133         kernel_cap_t dest;
134         CAP_BOP_ALL(dest, a, drop, &~);
135         return dest;
136 }
137 
138 static inline kernel_cap_t cap_invert(const kernel_cap_t c)
139 {
140         kernel_cap_t dest;
141         CAP_UOP_ALL(dest, c, ~);
142         return dest;
143 }
144 
145 static inline int cap_isclear(const kernel_cap_t a)
146 {
147         unsigned __capi;
148         CAP_FOR_EACH_U32(__capi) {
149                 if (a.cap[__capi] != 0)
150                         return 0;
151         }
152         return 1;
153 }
154 
155 /*
156  * Check if "a" is a subset of "set".
157  * return 1 if ALL of the capabilities in "a" are also in "set"
158  *      cap_issubset(0101, 1111) will return 1
159  * return 0 if ANY of the capabilities in "a" are not in "set"
160  *      cap_issubset(1111, 0101) will return 0
161  */
162 static inline int cap_issubset(const kernel_cap_t a, const kernel_cap_t set)
163 {
164         kernel_cap_t dest;
165         dest = cap_drop(a, set);
166         return cap_isclear(dest);
167 }
168 
169 /* Used to decide between falling back on the old suser() or fsuser(). */
170 
171 static inline int cap_is_fs_cap(int cap)
172 {
173         const kernel_cap_t __cap_fs_set = CAP_FS_SET;
174         return !!(CAP_TO_MASK(cap) & __cap_fs_set.cap[CAP_TO_INDEX(cap)]);
175 }
176 
177 static inline kernel_cap_t cap_drop_fs_set(const kernel_cap_t a)
178 {
179         const kernel_cap_t __cap_fs_set = CAP_FS_SET;
180         return cap_drop(a, __cap_fs_set);
181 }
182 
183 static inline kernel_cap_t cap_raise_fs_set(const kernel_cap_t a,
184                                             const kernel_cap_t permitted)
185 {
186         const kernel_cap_t __cap_fs_set = CAP_FS_SET;
187         return cap_combine(a,
188                            cap_intersect(permitted, __cap_fs_set));
189 }
190 
191 static inline kernel_cap_t cap_drop_nfsd_set(const kernel_cap_t a)
192 {
193         const kernel_cap_t __cap_fs_set = CAP_NFSD_SET;
194         return cap_drop(a, __cap_fs_set);
195 }
196 
197 static inline kernel_cap_t cap_raise_nfsd_set(const kernel_cap_t a,
198                                               const kernel_cap_t permitted)
199 {
200         const kernel_cap_t __cap_nfsd_set = CAP_NFSD_SET;
201         return cap_combine(a,
202                            cap_intersect(permitted, __cap_nfsd_set));
203 }
204 
205 extern bool has_capability(struct task_struct *t, int cap);
206 extern bool has_ns_capability(struct task_struct *t,
207                               struct user_namespace *ns, int cap);
208 extern bool has_capability_noaudit(struct task_struct *t, int cap);
209 extern bool has_ns_capability_noaudit(struct task_struct *t,
210                                       struct user_namespace *ns, int cap);
211 extern bool capable(int cap);
212 extern bool ns_capable(struct user_namespace *ns, int cap);
213 extern bool capable_wrt_inode_uidgid(const struct inode *inode, int cap);
214 extern bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap);
215 
216 /* audit system wants to get cap info from files as well */
217 extern int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps);
218 
219 #endif /* !_LINUX_CAPABILITY_H */
220 

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