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
 22extern int file_caps_enabled;
 23
 24typedef struct { u64 val; } kernel_cap_t;
 25
 26/* same as vfs_ns_cap_data but in cpu endian and always filled completely */
 27struct 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
 37struct file;
 38struct inode;
 39struct dentry;
 40struct task_struct;
 41struct user_namespace;
 42struct 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
 77static 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
 83static 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
 89static 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
 95static inline bool cap_isclear(const kernel_cap_t a)
 96{
 97	return !a.val;
 98}
 99
100static 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 */
112static 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
119static inline kernel_cap_t cap_drop_fs_set(const kernel_cap_t a)
120{
121	return cap_drop(a, CAP_FS_SET);
122}
123
124static 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
130static inline kernel_cap_t cap_drop_nfsd_set(const kernel_cap_t a)
131{
132	return cap_drop(a, CAP_NFSD_SET);
133}
134
135static 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
142extern bool has_ns_capability(struct task_struct *t,
143			      struct user_namespace *ns, int cap);
144extern bool has_capability_noaudit(struct task_struct *t, int cap);
145extern bool has_ns_capability_noaudit(struct task_struct *t,
146				      struct user_namespace *ns, int cap);
147extern bool capable(int cap);
148extern bool ns_capable(struct user_namespace *ns, int cap);
149extern bool ns_capable_noaudit(struct user_namespace *ns, int cap);
150extern bool ns_capable_setid(struct user_namespace *ns, int cap);
151#else
152static inline bool has_ns_capability(struct task_struct *t,
153			      struct user_namespace *ns, int cap)
154{
155	return true;
156}
157static inline bool has_capability_noaudit(struct task_struct *t, int cap)
158{
159	return true;
160}
161static inline bool has_ns_capability_noaudit(struct task_struct *t,
162				      struct user_namespace *ns, int cap)
163{
164	return true;
165}
166static inline bool capable(int cap)
167{
168	return true;
169}
170static inline bool ns_capable(struct user_namespace *ns, int cap)
171{
172	return true;
173}
174static inline bool ns_capable_noaudit(struct user_namespace *ns, int cap)
175{
176	return true;
177}
178static inline bool ns_capable_setid(struct user_namespace *ns, int cap)
179{
180	return true;
181}
182#endif /* CONFIG_MULTIUSER */
183bool privileged_wrt_inode_uidgid(struct user_namespace *ns,
184				 struct mnt_idmap *idmap,
185				 const struct inode *inode);
186bool capable_wrt_inode_uidgid(struct mnt_idmap *idmap,
187			      const struct inode *inode, int cap);
188extern bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap);
189extern bool ptracer_capable(struct task_struct *tsk, struct user_namespace *ns);
190static inline bool perfmon_capable(void)
191{
192	return capable(CAP_PERFMON) || capable(CAP_SYS_ADMIN);
193}
194
195static inline bool bpf_capable(void)
196{
197	return capable(CAP_BPF) || capable(CAP_SYS_ADMIN);
198}
199
200static inline bool checkpoint_restore_ns_capable(struct user_namespace *ns)
201{
202	return ns_capable(ns, CAP_CHECKPOINT_RESTORE) ||
203		ns_capable(ns, CAP_SYS_ADMIN);
204}
205
206static inline bool checkpoint_restore_ns_capable_noaudit(struct user_namespace *ns)
207{
208	return ns_capable_noaudit(ns, CAP_CHECKPOINT_RESTORE) ||
209		ns_capable_noaudit(ns, CAP_SYS_ADMIN);
210}
211
212/* audit system wants to get cap info from files as well */
213int get_vfs_caps_from_disk(struct mnt_idmap *idmap,
214			   const struct dentry *dentry,
215			   struct cpu_vfs_cap_data *cpu_caps);
216
217int cap_convert_nscap(struct mnt_idmap *idmap, struct dentry *dentry,
218		      const void **ivalue, size_t size);
219
220#endif /* !_LINUX_CAPABILITY_H */