linux/include/linux/capability.h
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   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
  21extern int file_caps_enabled;
  22
  23typedef 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 */
  28struct 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
  38struct file;
  39struct inode;
  40struct dentry;
  41struct user_namespace;
  42
  43struct user_namespace *current_user_ns(void);
  44
  45extern const kernel_cap_t __cap_empty_set;
  46extern 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)                                    \
  99do {                                                                \
 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)                                       \
 107do {                                                                \
 108        unsigned __capi;                                            \
 109        CAP_FOR_EACH_U32(__capi) {                                  \
 110                c.cap[__capi] = OP a.cap[__capi];                   \
 111        }                                                           \
 112} while (0)
 113
 114static 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
 122static 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
 130static 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
 138static 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
 145static 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 */
 162static 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
 171static 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
 177static 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
 183static 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
 191static 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
 197static 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
 205extern bool has_capability(struct task_struct *t, int cap);
 206extern bool has_ns_capability(struct task_struct *t,
 207                              struct user_namespace *ns, int cap);
 208extern bool has_capability_noaudit(struct task_struct *t, int cap);
 209extern bool has_ns_capability_noaudit(struct task_struct *t,
 210                                      struct user_namespace *ns, int cap);
 211extern bool capable(int cap);
 212extern bool ns_capable(struct user_namespace *ns, int cap);
 213extern bool nsown_capable(int cap);
 214extern bool inode_capable(const struct inode *inode, int cap);
 215extern bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap);
 216
 217/* audit system wants to get cap info from files as well */
 218extern int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps);
 219
 220#endif /* !_LINUX_CAPABILITY_H */
 221
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