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 */