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