include/linux/capability.h

0001 /* SPDX-License-Identifier: GPL-2.0 */
0002 /*
0003  * This is <linux/capability.h>
0004  *
0005  * Andrew G. Morgan <morgan@kernel.org>
0006  * Alexander Kjeldaas <astor@guardian.no>
0007  * with help from Aleph1, Roland Buresund and Andrew Main.
0008  *
0009  * See here for the libcap library ("POSIX draft" compliance):
0010  *
0011  * ftp://www.kernel.org/pub/linux/libs/security/linux-privs/kernel-2.6/
0012  */
0013 #ifndef _LINUX_CAPABILITY_H
0014 #define _LINUX_CAPABILITY_H
0015
0016 #include <uapi/linux/capability.h>
0017 #include <linux/uidgid.h>
0018
0019 #define _KERNEL_CAPABILITY_VERSION _LINUX_CAPABILITY_VERSION_3
0020 #define _KERNEL_CAPABILITY_U32S    _LINUX_CAPABILITY_U32S_3
0021
0022 extern int file_caps_enabled;
0023
0024 typedef struct kernel_cap_struct {
0025     __u32 cap[_KERNEL_CAPABILITY_U32S];
0026 } kernel_cap_t;
0027
0028 /* same as vfs_ns_cap_data but in cpu endian and always filled completely */
0029 struct cpu_vfs_cap_data {
0030     __u32 magic_etc;
0031     kernel_cap_t permitted;
0032     kernel_cap_t inheritable;
0033     kuid_t rootid;
0034 };
0035
0036 #define _USER_CAP_HEADER_SIZE  (sizeof(struct __user_cap_header_struct))
0037 #define _KERNEL_CAP_T_SIZE     (sizeof(kernel_cap_t))
0038
0039
0040 struct file;
0041 struct inode;
0042 struct dentry;
0043 struct task_struct;
0044 struct user_namespace;
0045
0046 extern const kernel_cap_t __cap_empty_set;
0047 extern const kernel_cap_t __cap_init_eff_set;
0048
0049 /*
0050  * Internal kernel functions only
0051  */
0052
0053 #define CAP_FOR_EACH_U32(__capi)  \
0054     for (__capi = 0; __capi < _KERNEL_CAPABILITY_U32S; ++__capi)
0055
0056 /*
0057  * CAP_FS_MASK and CAP_NFSD_MASKS:
0058  *
0059  * The fs mask is all the privileges that fsuid==0 historically meant.
0060  * At one time in the past, that included CAP_MKNOD and CAP_LINUX_IMMUTABLE.
0061  *
0062  * It has never meant setting security.* and trusted.* xattrs.
0063  *
0064  * We could also define fsmask as follows:
0065  *   1. CAP_FS_MASK is the privilege to bypass all fs-related DAC permissions
0066  *   2. The security.* and trusted.* xattrs are fs-related MAC permissions
0067  */
0068
0069 # define CAP_FS_MASK_B0     (CAP_TO_MASK(CAP_CHOWN)     \
0070                 | CAP_TO_MASK(CAP_MKNOD)        \
0071                 | CAP_TO_MASK(CAP_DAC_OVERRIDE) \
0072                 | CAP_TO_MASK(CAP_DAC_READ_SEARCH)  \
0073                 | CAP_TO_MASK(CAP_FOWNER)       \
0074                 | CAP_TO_MASK(CAP_FSETID))
0075
0076 # define CAP_FS_MASK_B1     (CAP_TO_MASK(CAP_MAC_OVERRIDE))
0077
0078 #if _KERNEL_CAPABILITY_U32S != 2
0079 # error Fix up hand-coded capability macro initializers
0080 #else /* HAND-CODED capability initializers */
0081
0082 #define CAP_LAST_U32            ((_KERNEL_CAPABILITY_U32S) - 1)
0083 #define CAP_LAST_U32_VALID_MASK     (CAP_TO_MASK(CAP_LAST_CAP + 1) -1)
0084
0085 # define CAP_EMPTY_SET    ((kernel_cap_t){{ 0, 0 }})
0086 # define CAP_FULL_SET     ((kernel_cap_t){{ ~0, CAP_LAST_U32_VALID_MASK }})
0087 # define CAP_FS_SET       ((kernel_cap_t){{ CAP_FS_MASK_B0 \
0088                     | CAP_TO_MASK(CAP_LINUX_IMMUTABLE), \
0089                     CAP_FS_MASK_B1 } })
0090 # define CAP_NFSD_SET     ((kernel_cap_t){{ CAP_FS_MASK_B0 \
0091                     | CAP_TO_MASK(CAP_SYS_RESOURCE), \
0092                     CAP_FS_MASK_B1 } })
0093
0094 #endif /* _KERNEL_CAPABILITY_U32S != 2 */
0095
0096 # define cap_clear(c)         do { (c) = __cap_empty_set; } while (0)
0097
0098 #define cap_raise(c, flag)  ((c).cap[CAP_TO_INDEX(flag)] |= CAP_TO_MASK(flag))
0099 #define cap_lower(c, flag)  ((c).cap[CAP_TO_INDEX(flag)] &= ~CAP_TO_MASK(flag))
0100 #define cap_raised(c, flag) ((c).cap[CAP_TO_INDEX(flag)] & CAP_TO_MASK(flag))
0101
0102 #define CAP_BOP_ALL(c, a, b, OP)                                    \
0103 do {                                                                \
0104     unsigned __capi;                                            \
0105     CAP_FOR_EACH_U32(__capi) {                                  \
0106         c.cap[__capi] = a.cap[__capi] OP b.cap[__capi];     \
0107     }                                                           \
0108 } while (0)
0109
0110 #define CAP_UOP_ALL(c, a, OP)                                       \
0111 do {                                                                \
0112     unsigned __capi;                                            \
0113     CAP_FOR_EACH_U32(__capi) {                                  \
0114         c.cap[__capi] = OP a.cap[__capi];                   \
0115     }                                                           \
0116 } while (0)
0117
0118 static inline kernel_cap_t cap_combine(const kernel_cap_t a,
0119                        const kernel_cap_t b)
0120 {
0121     kernel_cap_t dest;
0122     CAP_BOP_ALL(dest, a, b, |);
0123     return dest;
0124 }
0125
0126 static inline kernel_cap_t cap_intersect(const kernel_cap_t a,
0127                      const kernel_cap_t b)
0128 {
0129     kernel_cap_t dest;
0130     CAP_BOP_ALL(dest, a, b, &);
0131     return dest;
0132 }
0133
0134 static inline kernel_cap_t cap_drop(const kernel_cap_t a,
0135                     const kernel_cap_t drop)
0136 {
0137     kernel_cap_t dest;
0138     CAP_BOP_ALL(dest, a, drop, &~);
0139     return dest;
0140 }
0141
0142 static inline kernel_cap_t cap_invert(const kernel_cap_t c)
0143 {
0144     kernel_cap_t dest;
0145     CAP_UOP_ALL(dest, c, ~);
0146     return dest;
0147 }
0148
0149 static inline bool cap_isclear(const kernel_cap_t a)
0150 {
0151     unsigned __capi;
0152     CAP_FOR_EACH_U32(__capi) {
0153         if (a.cap[__capi] != 0)
0154             return false;
0155     }
0156     return true;
0157 }
0158
0159 /*
0160  * Check if "a" is a subset of "set".
0161  * return true if ALL of the capabilities in "a" are also in "set"
0162  *  cap_issubset(0101, 1111) will return true
0163  * return false if ANY of the capabilities in "a" are not in "set"
0164  *  cap_issubset(1111, 0101) will return false
0165  */
0166 static inline bool cap_issubset(const kernel_cap_t a, const kernel_cap_t set)
0167 {
0168     kernel_cap_t dest;
0169     dest = cap_drop(a, set);
0170     return cap_isclear(dest);
0171 }
0172
0173 /* Used to decide between falling back on the old suser() or fsuser(). */
0174
0175 static inline kernel_cap_t cap_drop_fs_set(const kernel_cap_t a)
0176 {
0177     const kernel_cap_t __cap_fs_set = CAP_FS_SET;
0178     return cap_drop(a, __cap_fs_set);
0179 }
0180
0181 static inline kernel_cap_t cap_raise_fs_set(const kernel_cap_t a,
0182                         const kernel_cap_t permitted)
0183 {
0184     const kernel_cap_t __cap_fs_set = CAP_FS_SET;
0185     return cap_combine(a,
0186                cap_intersect(permitted, __cap_fs_set));
0187 }
0188
0189 static inline kernel_cap_t cap_drop_nfsd_set(const kernel_cap_t a)
0190 {
0191     const kernel_cap_t __cap_fs_set = CAP_NFSD_SET;
0192     return cap_drop(a, __cap_fs_set);
0193 }
0194
0195 static inline kernel_cap_t cap_raise_nfsd_set(const kernel_cap_t a,
0196                           const kernel_cap_t permitted)
0197 {
0198     const kernel_cap_t __cap_nfsd_set = CAP_NFSD_SET;
0199     return cap_combine(a,
0200                cap_intersect(permitted, __cap_nfsd_set));
0201 }
0202
0203 #ifdef CONFIG_MULTIUSER
0204 extern bool has_capability(struct task_struct *t, int cap);
0205 extern bool has_ns_capability(struct task_struct *t,
0206                   struct user_namespace *ns, int cap);
0207 extern bool has_capability_noaudit(struct task_struct *t, int cap);
0208 extern bool has_ns_capability_noaudit(struct task_struct *t,
0209                       struct user_namespace *ns, int cap);
0210 extern bool capable(int cap);
0211 extern bool ns_capable(struct user_namespace *ns, int cap);
0212 extern bool ns_capable_noaudit(struct user_namespace *ns, int cap);
0213 extern bool ns_capable_setid(struct user_namespace *ns, int cap);
0214 #else
0215 static inline bool has_capability(struct task_struct *t, int cap)
0216 {
0217     return true;
0218 }
0219 static inline bool has_ns_capability(struct task_struct *t,
0220                   struct user_namespace *ns, int cap)
0221 {
0222     return true;
0223 }
0224 static inline bool has_capability_noaudit(struct task_struct *t, int cap)
0225 {
0226     return true;
0227 }
0228 static inline bool has_ns_capability_noaudit(struct task_struct *t,
0229                       struct user_namespace *ns, int cap)
0230 {
0231     return true;
0232 }
0233 static inline bool capable(int cap)
0234 {
0235     return true;
0236 }
0237 static inline bool ns_capable(struct user_namespace *ns, int cap)
0238 {
0239     return true;
0240 }
0241 static inline bool ns_capable_noaudit(struct user_namespace *ns, int cap)
0242 {
0243     return true;
0244 }
0245 static inline bool ns_capable_setid(struct user_namespace *ns, int cap)
0246 {
0247     return true;
0248 }
0249 #endif /* CONFIG_MULTIUSER */
0250 bool privileged_wrt_inode_uidgid(struct user_namespace *ns,
0251                  struct user_namespace *mnt_userns,
0252                  const struct inode *inode);
0253 bool capable_wrt_inode_uidgid(struct user_namespace *mnt_userns,
0254                   const struct inode *inode, int cap);
0255 extern bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap);
0256 extern bool ptracer_capable(struct task_struct *tsk, struct user_namespace *ns);
0257 static inline bool perfmon_capable(void)
0258 {
0259     return capable(CAP_PERFMON) || capable(CAP_SYS_ADMIN);
0260 }
0261
0262 static inline bool bpf_capable(void)
0263 {
0264     return capable(CAP_BPF) || capable(CAP_SYS_ADMIN);
0265 }
0266
0267 static inline bool checkpoint_restore_ns_capable(struct user_namespace *ns)
0268 {
0269     return ns_capable(ns, CAP_CHECKPOINT_RESTORE) ||
0270         ns_capable(ns, CAP_SYS_ADMIN);
0271 }
0272
0273 /* audit system wants to get cap info from files as well */
0274 int get_vfs_caps_from_disk(struct user_namespace *mnt_userns,
0275                const struct dentry *dentry,
0276                struct cpu_vfs_cap_data *cpu_caps);
0277
0278 int cap_convert_nscap(struct user_namespace *mnt_userns, struct dentry *dentry,
0279               const void **ivalue, size_t size);
0280
0281 #endif /* !_LINUX_CAPABILITY_H */