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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
1da177e4 LT |
2 | #ifndef _LINUX_HIGHUID_H |
3 | #define _LINUX_HIGHUID_H | |
4 | ||
1da177e4 LT |
5 | #include <linux/types.h> |
6 | ||
7 | /* | |
8 | * general notes: | |
9 | * | |
10 | * CONFIG_UID16 is defined if the given architecture needs to | |
11 | * support backwards compatibility for old system calls. | |
12 | * | |
13 | * kernel code should use uid_t and gid_t at all times when dealing with | |
14 | * kernel-private data. | |
15 | * | |
16 | * old_uid_t and old_gid_t should only be different if CONFIG_UID16 is | |
17 | * defined, else the platform should provide dummy typedefs for them | |
18 | * such that they are equivalent to __kernel_{u,g}id_t. | |
19 | * | |
20 | * uid16_t and gid16_t are used on all architectures. (when dealing | |
21 | * with structures hard coded to 16 bits, such as in filesystems) | |
22 | */ | |
23 | ||
24 | ||
25 | /* | |
26 | * This is the "overflow" UID and GID. They are used to signify uid/gid | |
27 | * overflow to old programs when they request uid/gid information but are | |
28 | * using the old 16 bit interfaces. | |
29 | * When you run a libc5 program, it will think that all highuid files or | |
30 | * processes are owned by this uid/gid. | |
31 | * The idea is that it's better to do so than possibly return 0 in lieu of | |
32 | * 65536, etc. | |
33 | */ | |
34 | ||
35 | extern int overflowuid; | |
36 | extern int overflowgid; | |
37 | ||
38 | extern void __bad_uid(void); | |
39 | extern void __bad_gid(void); | |
40 | ||
41 | #define DEFAULT_OVERFLOWUID 65534 | |
42 | #define DEFAULT_OVERFLOWGID 65534 | |
43 | ||
44 | #ifdef CONFIG_UID16 | |
45 | ||
46 | /* prevent uid mod 65536 effect by returning a default value for high UIDs */ | |
47 | #define high2lowuid(uid) ((uid) & ~0xFFFF ? (old_uid_t)overflowuid : (old_uid_t)(uid)) | |
48 | #define high2lowgid(gid) ((gid) & ~0xFFFF ? (old_gid_t)overflowgid : (old_gid_t)(gid)) | |
49 | /* | |
50 | * -1 is different in 16 bits than it is in 32 bits | |
51 | * these macros are used by chown(), setreuid(), ..., | |
52 | */ | |
53 | #define low2highuid(uid) ((uid) == (old_uid_t)-1 ? (uid_t)-1 : (uid_t)(uid)) | |
54 | #define low2highgid(gid) ((gid) == (old_gid_t)-1 ? (gid_t)-1 : (gid_t)(gid)) | |
55 | ||
56 | #define __convert_uid(size, uid) \ | |
57 | (size >= sizeof(uid) ? (uid) : high2lowuid(uid)) | |
58 | #define __convert_gid(size, gid) \ | |
59 | (size >= sizeof(gid) ? (gid) : high2lowgid(gid)) | |
60 | ||
61 | ||
62 | #else | |
63 | ||
64 | #define __convert_uid(size, uid) (uid) | |
65 | #define __convert_gid(size, gid) (gid) | |
66 | ||
67 | #endif /* !CONFIG_UID16 */ | |
68 | ||
69 | /* uid/gid input should be always 32bit uid_t */ | |
70 | #define SET_UID(var, uid) do { (var) = __convert_uid(sizeof(var), (uid)); } while (0) | |
71 | #define SET_GID(var, gid) do { (var) = __convert_gid(sizeof(var), (gid)); } while (0) | |
72 | ||
73 | /* | |
74 | * Everything below this line is needed on all architectures, to deal with | |
75 | * filesystems that only store 16 bits of the UID/GID, etc. | |
76 | */ | |
77 | ||
78 | /* | |
79 | * This is the UID and GID that will get written to disk if a filesystem | |
80 | * only supports 16-bit UIDs and the kernel has a high UID/GID to write | |
81 | */ | |
82 | extern int fs_overflowuid; | |
83 | extern int fs_overflowgid; | |
84 | ||
85 | #define DEFAULT_FS_OVERFLOWUID 65534 | |
86 | #define DEFAULT_FS_OVERFLOWGID 65534 | |
87 | ||
88 | /* | |
89 | * Since these macros are used in architectures that only need limited | |
90 | * 16-bit UID back compatibility, we won't use old_uid_t and old_gid_t | |
91 | */ | |
92 | #define fs_high2lowuid(uid) ((uid) & ~0xFFFF ? (uid16_t)fs_overflowuid : (uid16_t)(uid)) | |
93 | #define fs_high2lowgid(gid) ((gid) & ~0xFFFF ? (gid16_t)fs_overflowgid : (gid16_t)(gid)) | |
94 | ||
95 | #define low_16_bits(x) ((x) & 0xFFFF) | |
96 | #define high_16_bits(x) (((x) & 0xFFFF0000) >> 16) | |
97 | ||
98 | #endif /* _LINUX_HIGHUID_H */ |