1 files changed, 98 insertions, 0 deletions

diff --git a/include/linux/highuid.h b/include/linux/highuid.h
new file mode 100644
index 000000000000..53ecac3905e8
--- /dev/null
+++ b/include/linux/highuid.h
@@ -0,0 +1,98 @@
+#ifndef _LINUX_HIGHUID_H
+#define _LINUX_HIGHUID_H
+
+#include <linux/config.h>
+#include <linux/types.h>
+
+/*
+ * general notes:
+ *
+ * CONFIG_UID16 is defined if the given architecture needs to
+ * support backwards compatibility for old system calls.
+ *
+ * kernel code should use uid_t and gid_t at all times when dealing with
+ * kernel-private data.
+ *
+ * old_uid_t and old_gid_t should only be different if CONFIG_UID16 is
+ * defined, else the platform should provide dummy typedefs for them
+ * such that they are equivalent to __kernel_{u,g}id_t.
+ *
+ * uid16_t and gid16_t are used on all architectures. (when dealing
+ * with structures hard coded to 16 bits, such as in filesystems)
+ */
+
+
+/*
+ * This is the "overflow" UID and GID. They are used to signify uid/gid
+ * overflow to old programs when they request uid/gid information but are
+ * using the old 16 bit interfaces.
+ * When you run a libc5 program, it will think that all highuid files or
+ * processes are owned by this uid/gid.
+ * The idea is that it's better to do so than possibly return 0 in lieu of
+ * 65536, etc.
+ */
+
+extern int overflowuid;
+extern int overflowgid;
+
+extern void __bad_uid(void);
+extern void __bad_gid(void);
+
+#define DEFAULT_OVERFLOWUID     65534
+#define DEFAULT_OVERFLOWGID     65534
+
+#ifdef CONFIG_UID16
+
+/* prevent uid mod 65536 effect by returning a default value for high UIDs */
+#define high2lowuid(uid) ((uid) & ~0xFFFF ? (old_uid_t)overflowuid : (old_uid_t)(uid))
+#define high2lowgid(gid) ((gid) & ~0xFFFF ? (old_gid_t)overflowgid : (old_gid_t)(gid))
+/*
+ * -1 is different in 16 bits than it is in 32 bits
+ * these macros are used by chown(), setreuid(), ...,
+ */
+#define low2highuid(uid) ((uid) == (old_uid_t)-1 ? (uid_t)-1 : (uid_t)(uid))
+#define low2highgid(gid) ((gid) == (old_gid_t)-1 ? (gid_t)-1 : (gid_t)(gid))
+
+#define __convert_uid(size, uid) \
+        (size >= sizeof(uid) ? (uid) : high2lowuid(uid))
+#define __convert_gid(size, gid) \
+        (size >= sizeof(gid) ? (gid) : high2lowgid(gid))
+        
+
+#else
+
+#define __convert_uid(size, uid) (uid)
+#define __convert_gid(size, gid) (gid)
+
+#endif /* !CONFIG_UID16 */
+
+/* uid/gid input should be always 32bit uid_t */
+#define SET_UID(var, uid) do { (var) = __convert_uid(sizeof(var), (uid)); } while (0)
+#define SET_GID(var, gid) do { (var) = __convert_gid(sizeof(var), (gid)); } while (0)
+
+/*
+ * Everything below this line is needed on all architectures, to deal with
+ * filesystems that only store 16 bits of the UID/GID, etc.
+ */
+
+/*
+ * This is the UID and GID that will get written to disk if a filesystem
+ * only supports 16-bit UIDs and the kernel has a high UID/GID to write
+ */
+extern int fs_overflowuid;
+extern int fs_overflowgid;
+
+#define DEFAULT_FS_OVERFLOWUID  65534
+#define DEFAULT_FS_OVERFLOWGID  65534
+
+/*
+ * Since these macros are used in architectures that only need limited
+ * 16-bit UID back compatibility, we won't use old_uid_t and old_gid_t
+ */
+#define fs_high2lowuid(uid) ((uid) & ~0xFFFF ? (uid16_t)fs_overflowuid : (uid16_t)(uid))
+#define fs_high2lowgid(gid) ((gid) & ~0xFFFF ? (gid16_t)fs_overflowgid : (gid16_t)(gid))
+
+#define low_16_bits(x)  ((x) & 0xFFFF)
+#define high_16_bits(x) (((x) & 0xFFFF0000) >> 16)
+
+#endif /* _LINUX_HIGHUID_H */