1*4882a593Smuzhiyun /* SPDX-License-Identifier: GPL-2.0 */ 2*4882a593Smuzhiyun #ifndef _LINUX_HIGHUID_H 3*4882a593Smuzhiyun #define _LINUX_HIGHUID_H 4*4882a593Smuzhiyun 5*4882a593Smuzhiyun #include <linux/types.h> 6*4882a593Smuzhiyun 7*4882a593Smuzhiyun /* 8*4882a593Smuzhiyun * general notes: 9*4882a593Smuzhiyun * 10*4882a593Smuzhiyun * CONFIG_UID16 is defined if the given architecture needs to 11*4882a593Smuzhiyun * support backwards compatibility for old system calls. 12*4882a593Smuzhiyun * 13*4882a593Smuzhiyun * kernel code should use uid_t and gid_t at all times when dealing with 14*4882a593Smuzhiyun * kernel-private data. 15*4882a593Smuzhiyun * 16*4882a593Smuzhiyun * old_uid_t and old_gid_t should only be different if CONFIG_UID16 is 17*4882a593Smuzhiyun * defined, else the platform should provide dummy typedefs for them 18*4882a593Smuzhiyun * such that they are equivalent to __kernel_{u,g}id_t. 19*4882a593Smuzhiyun * 20*4882a593Smuzhiyun * uid16_t and gid16_t are used on all architectures. (when dealing 21*4882a593Smuzhiyun * with structures hard coded to 16 bits, such as in filesystems) 22*4882a593Smuzhiyun */ 23*4882a593Smuzhiyun 24*4882a593Smuzhiyun 25*4882a593Smuzhiyun /* 26*4882a593Smuzhiyun * This is the "overflow" UID and GID. They are used to signify uid/gid 27*4882a593Smuzhiyun * overflow to old programs when they request uid/gid information but are 28*4882a593Smuzhiyun * using the old 16 bit interfaces. 29*4882a593Smuzhiyun * When you run a libc5 program, it will think that all highuid files or 30*4882a593Smuzhiyun * processes are owned by this uid/gid. 31*4882a593Smuzhiyun * The idea is that it's better to do so than possibly return 0 in lieu of 32*4882a593Smuzhiyun * 65536, etc. 33*4882a593Smuzhiyun */ 34*4882a593Smuzhiyun 35*4882a593Smuzhiyun extern int overflowuid; 36*4882a593Smuzhiyun extern int overflowgid; 37*4882a593Smuzhiyun 38*4882a593Smuzhiyun extern void __bad_uid(void); 39*4882a593Smuzhiyun extern void __bad_gid(void); 40*4882a593Smuzhiyun 41*4882a593Smuzhiyun #define DEFAULT_OVERFLOWUID 65534 42*4882a593Smuzhiyun #define DEFAULT_OVERFLOWGID 65534 43*4882a593Smuzhiyun 44*4882a593Smuzhiyun #ifdef CONFIG_UID16 45*4882a593Smuzhiyun 46*4882a593Smuzhiyun /* prevent uid mod 65536 effect by returning a default value for high UIDs */ 47*4882a593Smuzhiyun #define high2lowuid(uid) ((uid) & ~0xFFFF ? (old_uid_t)overflowuid : (old_uid_t)(uid)) 48*4882a593Smuzhiyun #define high2lowgid(gid) ((gid) & ~0xFFFF ? (old_gid_t)overflowgid : (old_gid_t)(gid)) 49*4882a593Smuzhiyun /* 50*4882a593Smuzhiyun * -1 is different in 16 bits than it is in 32 bits 51*4882a593Smuzhiyun * these macros are used by chown(), setreuid(), ..., 52*4882a593Smuzhiyun */ 53*4882a593Smuzhiyun #define low2highuid(uid) ((uid) == (old_uid_t)-1 ? (uid_t)-1 : (uid_t)(uid)) 54*4882a593Smuzhiyun #define low2highgid(gid) ((gid) == (old_gid_t)-1 ? (gid_t)-1 : (gid_t)(gid)) 55*4882a593Smuzhiyun 56*4882a593Smuzhiyun #define __convert_uid(size, uid) \ 57*4882a593Smuzhiyun (size >= sizeof(uid) ? (uid) : high2lowuid(uid)) 58*4882a593Smuzhiyun #define __convert_gid(size, gid) \ 59*4882a593Smuzhiyun (size >= sizeof(gid) ? (gid) : high2lowgid(gid)) 60*4882a593Smuzhiyun 61*4882a593Smuzhiyun 62*4882a593Smuzhiyun #else 63*4882a593Smuzhiyun 64*4882a593Smuzhiyun #define __convert_uid(size, uid) (uid) 65*4882a593Smuzhiyun #define __convert_gid(size, gid) (gid) 66*4882a593Smuzhiyun 67*4882a593Smuzhiyun #endif /* !CONFIG_UID16 */ 68*4882a593Smuzhiyun 69*4882a593Smuzhiyun /* uid/gid input should be always 32bit uid_t */ 70*4882a593Smuzhiyun #define SET_UID(var, uid) do { (var) = __convert_uid(sizeof(var), (uid)); } while (0) 71*4882a593Smuzhiyun #define SET_GID(var, gid) do { (var) = __convert_gid(sizeof(var), (gid)); } while (0) 72*4882a593Smuzhiyun 73*4882a593Smuzhiyun /* 74*4882a593Smuzhiyun * Everything below this line is needed on all architectures, to deal with 75*4882a593Smuzhiyun * filesystems that only store 16 bits of the UID/GID, etc. 76*4882a593Smuzhiyun */ 77*4882a593Smuzhiyun 78*4882a593Smuzhiyun /* 79*4882a593Smuzhiyun * This is the UID and GID that will get written to disk if a filesystem 80*4882a593Smuzhiyun * only supports 16-bit UIDs and the kernel has a high UID/GID to write 81*4882a593Smuzhiyun */ 82*4882a593Smuzhiyun extern int fs_overflowuid; 83*4882a593Smuzhiyun extern int fs_overflowgid; 84*4882a593Smuzhiyun 85*4882a593Smuzhiyun #define DEFAULT_FS_OVERFLOWUID 65534 86*4882a593Smuzhiyun #define DEFAULT_FS_OVERFLOWGID 65534 87*4882a593Smuzhiyun 88*4882a593Smuzhiyun /* 89*4882a593Smuzhiyun * Since these macros are used in architectures that only need limited 90*4882a593Smuzhiyun * 16-bit UID back compatibility, we won't use old_uid_t and old_gid_t 91*4882a593Smuzhiyun */ 92*4882a593Smuzhiyun #define fs_high2lowuid(uid) ((uid) & ~0xFFFF ? (uid16_t)fs_overflowuid : (uid16_t)(uid)) 93*4882a593Smuzhiyun #define fs_high2lowgid(gid) ((gid) & ~0xFFFF ? (gid16_t)fs_overflowgid : (gid16_t)(gid)) 94*4882a593Smuzhiyun 95*4882a593Smuzhiyun #define low_16_bits(x) ((x) & 0xFFFF) 96*4882a593Smuzhiyun #define high_16_bits(x) (((x) & 0xFFFF0000) >> 16) 97*4882a593Smuzhiyun 98*4882a593Smuzhiyun #endif /* _LINUX_HIGHUID_H */ 99