Line data Source code
1 : #ifndef _LINUX_HIGHUID_H
2 : #define _LINUX_HIGHUID_H
3 :
4 : #include <linux/types.h>
5 :
6 : /*
7 : * general notes:
8 : *
9 : * CONFIG_UID16 is defined if the given architecture needs to
10 : * support backwards compatibility for old system calls.
11 : *
12 : * kernel code should use uid_t and gid_t at all times when dealing with
13 : * kernel-private data.
14 : *
15 : * old_uid_t and old_gid_t should only be different if CONFIG_UID16 is
16 : * defined, else the platform should provide dummy typedefs for them
17 : * such that they are equivalent to __kernel_{u,g}id_t.
18 : *
19 : * uid16_t and gid16_t are used on all architectures. (when dealing
20 : * with structures hard coded to 16 bits, such as in filesystems)
21 : */
22 :
23 :
24 : /*
25 : * This is the "overflow" UID and GID. They are used to signify uid/gid
26 : * overflow to old programs when they request uid/gid information but are
27 : * using the old 16 bit interfaces.
28 : * When you run a libc5 program, it will think that all highuid files or
29 : * processes are owned by this uid/gid.
30 : * The idea is that it's better to do so than possibly return 0 in lieu of
31 : * 65536, etc.
32 : */
33 :
34 : extern int overflowuid;
35 : extern int overflowgid;
36 :
37 : extern void __bad_uid(void);
38 : extern void __bad_gid(void);
39 :
40 : #define DEFAULT_OVERFLOWUID 65534
41 : #define DEFAULT_OVERFLOWGID 65534
42 :
43 : #ifdef CONFIG_UID16
44 :
45 : /* prevent uid mod 65536 effect by returning a default value for high UIDs */
46 : #define high2lowuid(uid) ((uid) & ~0xFFFF ? (old_uid_t)overflowuid : (old_uid_t)(uid))
47 : #define high2lowgid(gid) ((gid) & ~0xFFFF ? (old_gid_t)overflowgid : (old_gid_t)(gid))
48 : /*
49 : * -1 is different in 16 bits than it is in 32 bits
50 : * these macros are used by chown(), setreuid(), ...,
51 : */
52 : #define low2highuid(uid) ((uid) == (old_uid_t)-1 ? (uid_t)-1 : (uid_t)(uid))
53 : #define low2highgid(gid) ((gid) == (old_gid_t)-1 ? (gid_t)-1 : (gid_t)(gid))
54 :
55 : #define __convert_uid(size, uid) \
56 : (size >= sizeof(uid) ? (uid) : high2lowuid(uid))
57 : #define __convert_gid(size, gid) \
58 : (size >= sizeof(gid) ? (gid) : high2lowgid(gid))
59 :
60 :
61 : #else
62 :
63 : #define __convert_uid(size, uid) (uid)
64 : #define __convert_gid(size, gid) (gid)
65 :
66 : #endif /* !CONFIG_UID16 */
67 :
68 : /* uid/gid input should be always 32bit uid_t */
69 : #define SET_UID(var, uid) do { (var) = __convert_uid(sizeof(var), (uid)); } while (0)
70 : #define SET_GID(var, gid) do { (var) = __convert_gid(sizeof(var), (gid)); } while (0)
71 :
72 : /*
73 : * Everything below this line is needed on all architectures, to deal with
74 : * filesystems that only store 16 bits of the UID/GID, etc.
75 : */
76 :
77 : /*
78 : * This is the UID and GID that will get written to disk if a filesystem
79 : * only supports 16-bit UIDs and the kernel has a high UID/GID to write
80 : */
81 1 : extern int fs_overflowuid;
82 1 : extern int fs_overflowgid;
83 :
84 : #define DEFAULT_FS_OVERFLOWUID 65534
85 : #define DEFAULT_FS_OVERFLOWGID 65534
86 :
87 : /*
88 : * Since these macros are used in architectures that only need limited
89 : * 16-bit UID back compatibility, we won't use old_uid_t and old_gid_t
90 : */
91 : #define fs_high2lowuid(uid) ((uid) & ~0xFFFF ? (uid16_t)fs_overflowuid : (uid16_t)(uid))
92 : #define fs_high2lowgid(gid) ((gid) & ~0xFFFF ? (gid16_t)fs_overflowgid : (gid16_t)(gid))
93 :
94 : #define low_16_bits(x) ((x) & 0xFFFF)
95 : #define high_16_bits(x) (((x) & 0xFFFF0000) >> 16)
96 :
97 : #endif /* _LINUX_HIGHUID_H */
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