1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
|
#ifndef _LINUX_HIGHUID_H
#define _LINUX_HIGHUID_H
#include <linux/config.h>
#include <linux/types.h>
/*
* general notes:
*
* CONFIG_UID16 is defined if the given architecture needs to
* support backwards compatibility for old system calls.
*
* kernel code should use uid_t and gid_t at all times when dealing with
* kernel-private data.
*
* old_uid_t and old_gid_t should only be different if CONFIG_UID16 is
* defined, else the platform should provide dummy typedefs for them
* such that they are equivalent to __kernel_{u,g}id_t.
*
* uid16_t and gid16_t are used on all architectures. (when dealing
* with structures hard coded to 16 bits, such as in filesystems)
*/
/*
* This is the "overflow" UID and GID. They are used to signify uid/gid
* overflow to old programs when they request uid/gid information but are
* using the old 16 bit interfaces.
* When you run a libc5 program, it will think that all highuid files or
* processes are owned by this uid/gid.
* The idea is that it's better to do so than possibly return 0 in lieu of
* 65536, etc.
*/
extern int overflowuid;
extern int overflowgid;
#define DEFAULT_OVERFLOWUID 65534
#define DEFAULT_OVERFLOWGID 65534
#ifdef CONFIG_UID16
/* prevent uid mod 65536 effect by returning a default value for high UIDs */
#define high2lowuid(uid) ((uid) > 65535) ? (old_uid_t)overflowuid : (old_uid_t)(uid)
#define high2lowgid(gid) ((gid) > 65535) ? (old_gid_t)overflowgid : (old_gid_t)(gid)
/*
* -1 is different in 16 bits than it is in 32 bits
* these macros are used by chown(), setreuid(), ...,
*/
#define low2highuid(uid) ((uid) == (old_uid_t)-1) ? (uid_t)-1 : (uid_t)(uid)
#define low2highgid(gid) ((gid) == (old_gid_t)-1) ? (gid_t)-1 : (gid_t)(gid)
/* Avoid extra ifdefs with these macros */
#define SET_UID16(var, uid) var = high2lowuid(uid)
#define SET_GID16(var, gid) var = high2lowgid(gid)
#define NEW_TO_OLD_UID(uid) high2lowuid(uid)
#define NEW_TO_OLD_GID(gid) high2lowgid(gid)
/* specific to fs/stat.c */
#define SET_OLDSTAT_UID(stat, uid) (stat).st_uid = high2lowuid(uid)
#define SET_OLDSTAT_GID(stat, gid) (stat).st_gid = high2lowgid(gid)
#define SET_STAT_UID(stat, uid) (stat).st_uid = high2lowuid(uid)
#define SET_STAT_GID(stat, gid) (stat).st_gid = high2lowgid(gid)
#else
#define SET_UID16(var, uid) do { ; } while (0)
#define SET_GID16(var, gid) do { ; } while (0)
#define NEW_TO_OLD_UID(uid) uid
#define NEW_TO_OLD_GID(gid) gid
#define SET_OLDSTAT_UID(stat, uid) (stat).st_uid = uid
#define SET_OLDSTAT_GID(stat, gid) (stat).st_gid = gid
#define SET_STAT_UID(stat, uid) (stat).st_uid = uid
#define SET_STAT_GID(stat, gid) (stat).st_gid = gid
#endif /* CONFIG_UID16 */
/*
* Everything below this line is needed on all architectures, to deal with
* filesystems that only store 16 bits of the UID/GID, etc.
*/
/*
* This is the UID and GID that will get written to disk if a filesystem
* only supports 16-bit UIDs and the kernel has a high UID/GID to write
*/
extern int fs_overflowuid;
extern int fs_overflowgid;
#define DEFAULT_FS_OVERFLOWUID 65534
#define DEFAULT_FS_OVERFLOWGID 65534
/*
* Since these macros are used in architectures that only need limited
* 16-bit UID back compatibility, we won't use old_uid_t and old_gid_t
*/
#define fs_high2lowuid(uid) (uid > 65535) ? (uid16_t)fs_overflowuid : (uid16_t)uid
#define fs_high2lowgid(gid) (gid > 65535) ? (gid16_t)fs_overflowgid : (gid16_t)gid
#define low_16_bits(x) x & 0xFFFF
#define high_16_bits(x) (x & 0xFFFF0000) >> 16
#endif /* _LINUX_HIGHUID_H */
|
