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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_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)                                    \
102 do {                                                                \
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)                                       \
110 do {                                                                \
111         unsigned __capi;                                            \
112         CAP_FOR_EACH_U32(__capi) {                                  \
113                 c.cap[__capi] = OP a.cap[__capi];                   \
114         }                                                           \
115 } while (0)
116 
117 static 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 
125 static 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 
133 static 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 
141 static 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 
148 static 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  */
165 static 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 
174 static 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 
180 static 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 
186 static 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 
194 static 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 
200 static 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 extern bool has_capability(struct task_struct *t, int cap);
209 extern bool has_ns_capability(struct task_struct *t,
210                               struct user_namespace *ns, int cap);
211 extern bool has_capability_noaudit(struct task_struct *t, int cap);
212 extern bool has_ns_capability_noaudit(struct task_struct *t,
213                                       struct user_namespace *ns, int cap);
214 extern bool capable(int cap);
215 extern bool ns_capable(struct user_namespace *ns, int cap);
216 extern bool capable_wrt_inode_uidgid(const struct inode *inode, int cap);
217 extern bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap);
218 
219 /* audit system wants to get cap info from files as well */
220 extern int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps);
221 
222 #endif /* !_LINUX_CAPABILITY_H */
223 

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