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Rev | Author | Line No. | Line |
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422 | giacomo | 1 | #ifndef _LINUX_HIGHUID_H |
2 | #define _LINUX_HIGHUID_H |
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3 | |||
4 | #include <linux/config.h> |
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5 | #include <linux/types.h> |
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6 | |||
7 | /* |
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8 | * general notes: |
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9 | * |
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10 | * CONFIG_UID16 is defined if the given architecture needs to |
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11 | * support backwards compatibility for old system calls. |
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12 | * |
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13 | * kernel code should use uid_t and gid_t at all times when dealing with |
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14 | * kernel-private data. |
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15 | * |
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16 | * old_uid_t and old_gid_t should only be different if CONFIG_UID16 is |
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17 | * defined, else the platform should provide dummy typedefs for them |
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18 | * such that they are equivalent to __kernel_{u,g}id_t. |
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19 | * |
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20 | * uid16_t and gid16_t are used on all architectures. (when dealing |
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21 | * with structures hard coded to 16 bits, such as in filesystems) |
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22 | */ |
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23 | |||
24 | |||
25 | /* |
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26 | * This is the "overflow" UID and GID. They are used to signify uid/gid |
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27 | * overflow to old programs when they request uid/gid information but are |
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28 | * using the old 16 bit interfaces. |
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29 | * When you run a libc5 program, it will think that all highuid files or |
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30 | * processes are owned by this uid/gid. |
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31 | * The idea is that it's better to do so than possibly return 0 in lieu of |
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32 | * 65536, etc. |
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33 | */ |
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34 | |||
35 | extern int overflowuid; |
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36 | extern int overflowgid; |
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37 | |||
38 | extern void __bad_uid(void); |
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39 | extern void __bad_gid(void); |
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40 | |||
41 | #define DEFAULT_OVERFLOWUID 65534 |
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42 | #define DEFAULT_OVERFLOWGID 65534 |
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43 | |||
44 | #ifdef CONFIG_UID16 |
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45 | |||
46 | /* prevent uid mod 65536 effect by returning a default value for high UIDs */ |
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47 | #define high2lowuid(uid) ((uid) > 65535 ? (old_uid_t)overflowuid : (old_uid_t)(uid)) |
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48 | #define high2lowgid(gid) ((gid) > 65535 ? (old_gid_t)overflowgid : (old_gid_t)(gid)) |
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49 | /* |
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50 | * -1 is different in 16 bits than it is in 32 bits |
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51 | * these macros are used by chown(), setreuid(), ..., |
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52 | */ |
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53 | #define low2highuid(uid) ((uid) == (old_uid_t)-1 ? (uid_t)-1 : (uid_t)(uid)) |
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54 | #define low2highgid(gid) ((gid) == (old_gid_t)-1 ? (gid_t)-1 : (gid_t)(gid)) |
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55 | |||
56 | #define __convert_uid(size, uid) \ |
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57 | (size >= sizeof(uid) ? (uid) : high2lowuid(uid)) |
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58 | #define __convert_gid(size, gid) \ |
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59 | (size >= sizeof(gid) ? (gid) : high2lowgid(gid)) |
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60 | |||
61 | |||
62 | #else |
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63 | |||
64 | #define __convert_uid(size, uid) (uid) |
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65 | #define __convert_gid(size, gid) (gid) |
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66 | |||
67 | #endif /* !CONFIG_UID16 */ |
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68 | |||
69 | /* uid/gid input should be always 32bit uid_t */ |
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70 | #define SET_UID(var, uid) do { (var) = __convert_uid(sizeof(var), (uid)); } while (0) |
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71 | #define SET_GID(var, gid) do { (var) = __convert_gid(sizeof(var), (gid)); } while (0) |
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72 | |||
73 | /* |
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74 | * Everything below this line is needed on all architectures, to deal with |
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75 | * filesystems that only store 16 bits of the UID/GID, etc. |
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76 | */ |
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77 | |||
78 | /* |
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79 | * This is the UID and GID that will get written to disk if a filesystem |
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80 | * only supports 16-bit UIDs and the kernel has a high UID/GID to write |
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81 | */ |
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82 | extern int fs_overflowuid; |
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83 | extern int fs_overflowgid; |
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84 | |||
85 | #define DEFAULT_FS_OVERFLOWUID 65534 |
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86 | #define DEFAULT_FS_OVERFLOWGID 65534 |
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87 | |||
88 | /* |
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89 | * Since these macros are used in architectures that only need limited |
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90 | * 16-bit UID back compatibility, we won't use old_uid_t and old_gid_t |
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91 | */ |
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92 | #define fs_high2lowuid(uid) ((uid) > 65535 ? (uid16_t)fs_overflowuid : (uid16_t)(uid)) |
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93 | #define fs_high2lowgid(gid) ((gid) > 65535 ? (gid16_t)fs_overflowgid : (gid16_t)(gid)) |
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94 | |||
95 | #define low_16_bits(x) ((x) & 0xFFFF) |
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96 | #define high_16_bits(x) (((x) & 0xFFFF0000) >> 16) |
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97 | |||
98 | #endif /* _LINUX_HIGHUID_H */ |