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 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 */ 98