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 
cap_combine(const kernel_cap_t a,const kernel_cap_t b)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 
cap_intersect(const kernel_cap_t a,const kernel_cap_t b)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 
cap_drop(const kernel_cap_t a,const kernel_cap_t drop)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 
cap_isclear(const kernel_cap_t a)95 static inline bool cap_isclear(const kernel_cap_t a)
96 {
97 	return !a.val;
98 }
99 
cap_isidentical(const kernel_cap_t a,const kernel_cap_t b)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  */
cap_issubset(const kernel_cap_t a,const kernel_cap_t set)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 
cap_drop_fs_set(const kernel_cap_t a)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 
cap_raise_fs_set(const kernel_cap_t a,const kernel_cap_t permitted)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 
cap_drop_nfsd_set(const kernel_cap_t a)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 
cap_raise_nfsd_set(const kernel_cap_t a,const kernel_cap_t permitted)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
has_capability(struct task_struct * t,int cap)153 static inline bool has_capability(struct task_struct *t, int cap)
154 {
155 	return true;
156 }
has_ns_capability(struct task_struct * t,struct user_namespace * ns,int cap)157 static inline bool has_ns_capability(struct task_struct *t,
158 			      struct user_namespace *ns, int cap)
159 {
160 	return true;
161 }
has_capability_noaudit(struct task_struct * t,int cap)162 static inline bool has_capability_noaudit(struct task_struct *t, int cap)
163 {
164 	return true;
165 }
has_ns_capability_noaudit(struct task_struct * t,struct user_namespace * ns,int cap)166 static inline bool has_ns_capability_noaudit(struct task_struct *t,
167 				      struct user_namespace *ns, int cap)
168 {
169 	return true;
170 }
capable(int cap)171 static inline bool capable(int cap)
172 {
173 	return true;
174 }
ns_capable(struct user_namespace * ns,int cap)175 static inline bool ns_capable(struct user_namespace *ns, int cap)
176 {
177 	return true;
178 }
ns_capable_noaudit(struct user_namespace * ns,int cap)179 static inline bool ns_capable_noaudit(struct user_namespace *ns, int cap)
180 {
181 	return true;
182 }
ns_capable_setid(struct user_namespace * ns,int cap)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);
perfmon_capable(void)195 static inline bool perfmon_capable(void)
196 {
197 	return capable(CAP_PERFMON) || capable(CAP_SYS_ADMIN);
198 }
199 
bpf_capable(void)200 static inline bool bpf_capable(void)
201 {
202 	return capable(CAP_BPF) || capable(CAP_SYS_ADMIN);
203 }
204 
checkpoint_restore_ns_capable(struct user_namespace * ns)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 */
220