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 nsown_capable(int cap);
 217 extern bool capable_wrt_inode_uidgid(const struct inode *inode, int cap);
 218 extern bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap);
 219
 220 /* audit system wants to get cap info from files as well */
 221 extern int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps);
 222
 223 #endif /* !_LINUX_CAPABILITY_H */