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 #include <linux/uidgid.h>
  18 #include <linux/bits.h>
  19
  20 #define _KERNEL_CAPABILITY_VERSION _LINUX_CAPABILITY_VERSION_3
  21
  22 extern int file_caps_enabled;
  23
  24 typedef struct { u64 val; } kernel_cap_t;
  25
  26 /* same as vfs_ns_cap_data but in cpu endian and always filled completely */
  27 struct cpu_vfs_cap_data {
  28         __u32 magic_etc;
  29         kuid_t rootid;
  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 struct file;
  38 struct inode;
  39 struct dentry;
  40 struct task_struct;
  41 struct user_namespace;
  42 struct mnt_idmap;
  43
  44 /*
  45  * CAP_FS_MASK and CAP_NFSD_MASKS:
  46  *
  47  * The fs mask is all the privileges that fsuid==0 historically meant.
  48  * At one time in the past, that included CAP_MKNOD and CAP_LINUX_IMMUTABLE.
  49  *
  50  * It has never meant setting security.* and trusted.* xattrs.
  51  *
  52  * We could also define fsmask as follows:
  53  *   1. CAP_FS_MASK is the privilege to bypass all fs-related DAC permissions
  54  *   2. The security.* and trusted.* xattrs are fs-related MAC permissions
  55  */
  56
  57 # define CAP_FS_MASK     (BIT_ULL(CAP_CHOWN)            \
  58                         | BIT_ULL(CAP_MKNOD)            \
  59                         | BIT_ULL(CAP_DAC_OVERRIDE)     \
  60                         | BIT_ULL(CAP_DAC_READ_SEARCH)  \
  61                         | BIT_ULL(CAP_FOWNER)           \
  62                         | BIT_ULL(CAP_FSETID)           \
  63                         | BIT_ULL(CAP_MAC_OVERRIDE))
  64 #define CAP_VALID_MASK   (BIT_ULL(CAP_LAST_CAP+1)-1)
  65
  66 # define CAP_EMPTY_SET    ((kernel_cap_t) { 0 })
  67 # define CAP_FULL_SET     ((kernel_cap_t) { CAP_VALID_MASK })
  68 # define CAP_FS_SET       ((kernel_cap_t) { CAP_FS_MASK | BIT_ULL(CAP_LINUX_IMMUTABLE) })
  69 # define CAP_NFSD_SET     ((kernel_cap_t) { CAP_FS_MASK | BIT_ULL(CAP_SYS_RESOURCE) })
  70
  71 # define cap_clear(c)         do { (c).val = 0; } while (0)
  72
  73 #define cap_raise(c, flag)  ((c).val |= BIT_ULL(flag))
  74 #define cap_lower(c, flag)  ((c).val &= ~BIT_ULL(flag))
  75 #define cap_raised(c, flag) (((c).val & BIT_ULL(flag)) != 0)
  76
  77 static inline kernel_cap_t cap_combine(const kernel_cap_t a,
  78                                        const kernel_cap_t b)
  79 {
  80         return (kernel_cap_t) { a.val | b.val };
  81 }
  82
  83 static inline kernel_cap_t cap_intersect(const kernel_cap_t a,
  84                                          const kernel_cap_t b)
  85 {
  86         return (kernel_cap_t) { a.val & b.val };
  87 }
  88
  89 static inline kernel_cap_t cap_drop(const kernel_cap_t a,
  90                                     const kernel_cap_t drop)
  91 {
  92         return (kernel_cap_t) { a.val &~ drop.val };
  93 }
  94
  95 static inline bool cap_isclear(const kernel_cap_t a)
  96 {
  97         return !a.val;
  98 }
  99
 100 static inline bool cap_isidentical(const kernel_cap_t a, const kernel_cap_t b)
 101 {
 102         return a.val == b.val;
 103 }
 104
 105 /*
 106  * Check if "a" is a subset of "set".
 107  * return true if ALL of the capabilities in "a" are also in "set"
 108  *      cap_issubset(0101, 1111) will return true
 109  * return false if ANY of the capabilities in "a" are not in "set"
 110  *      cap_issubset(1111, 0101) will return false
 111  */
 112 static inline bool cap_issubset(const kernel_cap_t a, const kernel_cap_t set)
 113 {
 114         return !(a.val & ~set.val);
 115 }
 116
 117 /* Used to decide between falling back on the old suser() or fsuser(). */
 118
 119 static inline kernel_cap_t cap_drop_fs_set(const kernel_cap_t a)
 120 {
 121         return cap_drop(a, CAP_FS_SET);
 122 }
 123
 124 static inline kernel_cap_t cap_raise_fs_set(const kernel_cap_t a,
 125                                             const kernel_cap_t permitted)
 126 {
 127         return cap_combine(a, cap_intersect(permitted, CAP_FS_SET));
 128 }
 129
 130 static inline kernel_cap_t cap_drop_nfsd_set(const kernel_cap_t a)
 131 {
 132         return cap_drop(a, CAP_NFSD_SET);
 133 }
 134
 135 static inline kernel_cap_t cap_raise_nfsd_set(const kernel_cap_t a,
 136                                               const kernel_cap_t permitted)
 137 {
 138         return cap_combine(a, cap_intersect(permitted, CAP_NFSD_SET));
 139 }
 140
 141 #ifdef CONFIG_MULTIUSER
 142 extern bool has_capability(struct task_struct *t, int cap);
 143 extern bool has_ns_capability(struct task_struct *t,
 144                               struct user_namespace *ns, int cap);
 145 extern bool has_capability_noaudit(struct task_struct *t, int cap);
 146 extern bool has_ns_capability_noaudit(struct task_struct *t,
 147                                       struct user_namespace *ns, int cap);
 148 extern bool capable(int cap);
 149 extern bool ns_capable(struct user_namespace *ns, int cap);
 150 extern bool ns_capable_noaudit(struct user_namespace *ns, int cap);
 151 extern bool ns_capable_setid(struct user_namespace *ns, int cap);
 152 #else
 153 static inline bool has_capability(struct task_struct *t, int cap)
 154 {
 155         return true;
 156 }
 157 static inline bool has_ns_capability(struct task_struct *t,
 158                               struct user_namespace *ns, int cap)
 159 {
 160         return true;
 161 }
 162 static inline bool has_capability_noaudit(struct task_struct *t, int cap)
 163 {
 164         return true;
 165 }
 166 static inline bool has_ns_capability_noaudit(struct task_struct *t,
 167                                       struct user_namespace *ns, int cap)
 168 {
 169         return true;
 170 }
 171 static inline bool capable(int cap)
 172 {
 173         return true;
 174 }
 175 static inline bool ns_capable(struct user_namespace *ns, int cap)
 176 {
 177         return true;
 178 }
 179 static inline bool ns_capable_noaudit(struct user_namespace *ns, int cap)
 180 {
 181         return true;
 182 }
 183 static inline bool ns_capable_setid(struct user_namespace *ns, int cap)
 184 {
 185         return true;
 186 }
 187 #endif /* CONFIG_MULTIUSER */
 188 bool privileged_wrt_inode_uidgid(struct user_namespace *ns,
 189                                  struct mnt_idmap *idmap,
 190                                  const struct inode *inode);
 191 bool capable_wrt_inode_uidgid(struct mnt_idmap *idmap,
 192                               const struct inode *inode, int cap);
 193 extern bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap);
 194 extern bool ptracer_capable(struct task_struct *tsk, struct user_namespace *ns);
 195 static inline bool perfmon_capable(void)
 196 {
 197         return capable(CAP_PERFMON) || capable(CAP_SYS_ADMIN);
 198 }
 199
 200 static inline bool bpf_capable(void)
 201 {
 202         return capable(CAP_BPF) || capable(CAP_SYS_ADMIN);
 203 }
 204
 205 static inline bool checkpoint_restore_ns_capable(struct user_namespace *ns)
 206 {
 207         return ns_capable(ns, CAP_CHECKPOINT_RESTORE) ||
 208                 ns_capable(ns, CAP_SYS_ADMIN);
 209 }
 210
 211 /* audit system wants to get cap info from files as well */
 212 int get_vfs_caps_from_disk(struct mnt_idmap *idmap,
 213                            const struct dentry *dentry,
 214                            struct cpu_vfs_cap_data *cpu_caps);
 215
 216 int cap_convert_nscap(struct mnt_idmap *idmap, struct dentry *dentry,
 217                       const void **ivalue, size_t size);
 218
 219 #endif /* !_LINUX_CAPABILITY_H */