LXR linux/include/linux/capability.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2/*
   3 * This is <linux/capability.h>
   4 *
   5 * Andrew G. Morgan <morgan@kernel.org>
   6 * Alexander Kjeldaas <astor@guardian.no>
   7 * with help from Aleph1, Roland Buresund and Andrew Main.
   8 *
   9 * See here for the libcap library ("POSIX draft" compliance):
  10 *
  11 * ftp://www.kernel.org/pub/linux/libs/security/linux-privs/kernel-2.6/
  12 */
  13#ifndef _LINUX_CAPABILITY_H
  14#define _LINUX_CAPABILITY_H
  15
  16#include <uapi/linux/capability.h>
  17
  18
  19#define _KERNEL_CAPABILITY_VERSION _LINUX_CAPABILITY_VERSION_3
  20#define _KERNEL_CAPABILITY_U32S    _LINUX_CAPABILITY_U32S_3
  21
  22extern int file_caps_enabled;
  23
  24typedef struct kernel_cap_struct {
  25        __u32 cap[_KERNEL_CAPABILITY_U32S];
  26} kernel_cap_t;
  27
  28/* exact same as vfs_cap_data but in cpu endian and always filled completely */
  29struct cpu_vfs_cap_data {
  30        __u32 magic_etc;
  31        kernel_cap_t permitted;
  32        kernel_cap_t inheritable;
  33};
  34
  35#define _USER_CAP_HEADER_SIZE  (sizeof(struct __user_cap_header_struct))
  36#define _KERNEL_CAP_T_SIZE     (sizeof(kernel_cap_t))
  37
  38
  39struct file;
  40struct inode;
  41struct dentry;
  42struct task_struct;
  43struct user_namespace;
  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_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)                                    \
 102do {                                                                \
 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)                                       \
 110do {                                                                \
 111        unsigned __capi;                                            \
 112        CAP_FOR_EACH_U32(__capi) {                                  \
 113                c.cap[__capi] = OP a.cap[__capi];                   \
 114        }                                                           \
 115} while (0)
 116
 117static 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
 125static 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
 133static 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
 141static 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
 148static inline bool 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 false;
 154        }
 155        return true;
 156}
 157
 158/*
 159 * Check if "a" is a subset of "set".
 160 * return true if ALL of the capabilities in "a" are also in "set"
 161 *      cap_issubset(0101, 1111) will return true
 162 * return false if ANY of the capabilities in "a" are not in "set"
 163 *      cap_issubset(1111, 0101) will return false
 164 */
 165static inline bool 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
 174static inline kernel_cap_t cap_drop_fs_set(const kernel_cap_t a)
 175{
 176        const kernel_cap_t __cap_fs_set = CAP_FS_SET;
 177        return cap_drop(a, __cap_fs_set);
 178}
 179
 180static inline kernel_cap_t cap_raise_fs_set(const kernel_cap_t a,
 181                                            const kernel_cap_t permitted)
 182{
 183        const kernel_cap_t __cap_fs_set = CAP_FS_SET;
 184        return cap_combine(a,
 185                           cap_intersect(permitted, __cap_fs_set));
 186}
 187
 188static inline kernel_cap_t cap_drop_nfsd_set(const kernel_cap_t a)
 189{
 190        const kernel_cap_t __cap_fs_set = CAP_NFSD_SET;
 191        return cap_drop(a, __cap_fs_set);
 192}
 193
 194static inline kernel_cap_t cap_raise_nfsd_set(const kernel_cap_t a,
 195                                              const kernel_cap_t permitted)
 196{
 197        const kernel_cap_t __cap_nfsd_set = CAP_NFSD_SET;
 198        return cap_combine(a,
 199                           cap_intersect(permitted, __cap_nfsd_set));
 200}
 201
 202#ifdef CONFIG_MULTIUSER
 203extern bool has_capability(struct task_struct *t, int cap);
 204extern bool has_ns_capability(struct task_struct *t,
 205                              struct user_namespace *ns, int cap);
 206extern bool has_capability_noaudit(struct task_struct *t, int cap);
 207extern bool has_ns_capability_noaudit(struct task_struct *t,
 208                                      struct user_namespace *ns, int cap);
 209extern bool capable(int cap);
 210extern bool ns_capable(struct user_namespace *ns, int cap);
 211extern bool ns_capable_noaudit(struct user_namespace *ns, int cap);
 212#else
 213static inline bool has_capability(struct task_struct *t, int cap)
 214{
 215        return true;
 216}
 217static inline bool has_ns_capability(struct task_struct *t,
 218                              struct user_namespace *ns, int cap)
 219{
 220        return true;
 221}
 222static inline bool has_capability_noaudit(struct task_struct *t, int cap)
 223{
 224        return true;
 225}
 226static inline bool has_ns_capability_noaudit(struct task_struct *t,
 227                                      struct user_namespace *ns, int cap)
 228{
 229        return true;
 230}
 231static inline bool capable(int cap)
 232{
 233        return true;
 234}
 235static inline bool ns_capable(struct user_namespace *ns, int cap)
 236{
 237        return true;
 238}
 239static inline bool ns_capable_noaudit(struct user_namespace *ns, int cap)
 240{
 241        return true;
 242}
 243#endif /* CONFIG_MULTIUSER */
 244extern bool privileged_wrt_inode_uidgid(struct user_namespace *ns, const struct inode *inode);
 245extern bool capable_wrt_inode_uidgid(const struct inode *inode, int cap);
 246extern bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap);
 247extern bool ptracer_capable(struct task_struct *tsk, struct user_namespace *ns);
 248
 249/* audit system wants to get cap info from files as well */
 250extern int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps);
 251
 252extern int cap_convert_nscap(struct dentry *dentry, void **ivalue, size_t size);
 253
 254#endif /* !_LINUX_CAPABILITY_H */
 255