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1da177e4 LT |
1 | #ifndef _LINUX_HIGHUID_H |
2 | #define _LINUX_HIGHUID_H | |
3 | ||
1da177e4 LT |
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 | extern int fs_overflowuid; | |
82 | 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 */ |