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sys_oabi-compat.c

/*
 *  arch/arm/kernel/sys_oabi-compat.c
 *
 *  Compatibility wrappers for syscalls that are used from
 *  old ABI user space binaries with an EABI kernel.
 *
 *  Author: Nicolas Pitre
 *  Created:      Oct 7, 2005
 *  Copyright:    MontaVista Software, Inc.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 */

/*
 * The legacy ABI and the new ARM EABI have different rules making some
 * syscalls incompatible especially with structure arguments.
 * Most notably, Eabi says 64-bit members should be 64-bit aligned instead of
 * simply word aligned.  EABI also pads structures to the size of the largest
 * member it contains instead of the invariant 32-bit.
 *
 * The following syscalls are affected:
 *
 * sys_stat64:
 * sys_lstat64:
 * sys_fstat64:
 * sys_fstatat64:
 *
 *   struct stat64 has different sizes and some members are shifted
 *   Compatibility wrappers are needed for them and provided below.
 *
 * sys_fcntl64:
 *
 *   struct flock64 has different sizes and some members are shifted
 *   A compatibility wrapper is needed and provided below.
 *
 * sys_statfs64:
 * sys_fstatfs64:
 *
 *   struct statfs64 has extra padding with EABI growing its size from
 *   84 to 88.  This struct is now __attribute__((packed,aligned(4)))
 *   with a small assembly wrapper to force the sz argument to 84 if it is 88
 *   to avoid copying the extra padding over user space unexpecting it.
 *
 * sys_newuname:
 *
 *   struct new_utsname has no padding with EABI.  No problem there.
 *
 * sys_epoll_ctl:
 * sys_epoll_wait:
 *
 *   struct epoll_event has its second member shifted also affecting the
 *   structure size. Compatibility wrappers are needed and provided below.
 *
 * sys_ipc:
 * sys_semop:
 * sys_semtimedop:
 *
 *   struct sembuf loses its padding with EABI.  Since arrays of them are
 *   used they have to be copyed to remove the padding. Compatibility wrappers
 *   provided below.
 *
 * sys_bind:
 * sys_connect:
 * sys_sendmsg:
 * sys_sendto:
 * sys_socketcall:
 *
 *   struct sockaddr_un loses its padding with EABI.  Since the size of the
 *   structure is used as a validation test in unix_mkname(), we need to
 *   change the length argument to 110 whenever it is 112.  Compatibility
 *   wrappers provided below.
 */

#include <linux/syscalls.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/fcntl.h>
#include <linux/eventpoll.h>
#include <linux/sem.h>
#include <linux/socket.h>
#include <linux/net.h>
#include <linux/ipc.h>
#include <asm/uaccess.h>

struct oldabi_stat64 {
      unsigned long long st_dev;
      unsigned int      __pad1;
      unsigned long     __st_ino;
      unsigned int      st_mode;
      unsigned int      st_nlink;

      unsigned long     st_uid;
      unsigned long     st_gid;

      unsigned long long st_rdev;
      unsigned int      __pad2;

      long long   st_size;
      unsigned long     st_blksize;
      unsigned long long st_blocks;

      unsigned long     st_atime;
      unsigned long     st_atime_nsec;

      unsigned long     st_mtime;
      unsigned long     st_mtime_nsec;

      unsigned long     st_ctime;
      unsigned long     st_ctime_nsec;

      unsigned long long st_ino;
} __attribute__ ((packed,aligned(4)));

static long cp_oldabi_stat64(struct kstat *stat,
                       struct oldabi_stat64 __user *statbuf)
{
      struct oldabi_stat64 tmp;

      tmp.st_dev = huge_encode_dev(stat->dev);
      tmp.__pad1 = 0;
      tmp.__st_ino = stat->ino;
      tmp.st_mode = stat->mode;
      tmp.st_nlink = stat->nlink;
      tmp.st_uid = stat->uid;
      tmp.st_gid = stat->gid;
      tmp.st_rdev = huge_encode_dev(stat->rdev);
      tmp.st_size = stat->size;
      tmp.st_blocks = stat->blocks;
      tmp.__pad2 = 0;
      tmp.st_blksize = stat->blksize;
      tmp.st_atime = stat->atime.tv_sec;
      tmp.st_atime_nsec = stat->atime.tv_nsec;
      tmp.st_mtime = stat->mtime.tv_sec;
      tmp.st_mtime_nsec = stat->mtime.tv_nsec;
      tmp.st_ctime = stat->ctime.tv_sec;
      tmp.st_ctime_nsec = stat->ctime.tv_nsec;
      tmp.st_ino = stat->ino;
      return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
}

asmlinkage long sys_oabi_stat64(char __user * filename,
                        struct oldabi_stat64 __user * statbuf)
{
      struct kstat stat;
      int error = vfs_stat(filename, &stat);
      if (!error)
            error = cp_oldabi_stat64(&stat, statbuf);
      return error;
}

asmlinkage long sys_oabi_lstat64(char __user * filename,
                         struct oldabi_stat64 __user * statbuf)
{
      struct kstat stat;
      int error = vfs_lstat(filename, &stat);
      if (!error)
            error = cp_oldabi_stat64(&stat, statbuf);
      return error;
}

asmlinkage long sys_oabi_fstat64(unsigned long fd,
                         struct oldabi_stat64 __user * statbuf)
{
      struct kstat stat;
      int error = vfs_fstat(fd, &stat);
      if (!error)
            error = cp_oldabi_stat64(&stat, statbuf);
      return error;
}

asmlinkage long sys_oabi_fstatat64(int dfd,
                           char __user *filename,
                           struct oldabi_stat64  __user *statbuf,
                           int flag)
{
      struct kstat stat;
      int error = -EINVAL;

      if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)
            goto out;

      if (flag & AT_SYMLINK_NOFOLLOW)
            error = vfs_lstat_fd(dfd, filename, &stat);
      else
            error = vfs_stat_fd(dfd, filename, &stat);

      if (!error)
      error = cp_oldabi_stat64(&stat, statbuf);

out:
      return error;
}

struct oabi_flock64 {
      short l_type;
      short l_whence;
      loff_t      l_start;
      loff_t      l_len;
      pid_t l_pid;
} __attribute__ ((packed,aligned(4)));

asmlinkage long sys_oabi_fcntl64(unsigned int fd, unsigned int cmd,
                         unsigned long arg)
{
      struct oabi_flock64 user;
      struct flock64 kernel;
      mm_segment_t fs = USER_DS; /* initialized to kill a warning */
      unsigned long local_arg = arg;
      int ret;

      switch (cmd) {
      case F_GETLK64:
      case F_SETLK64:
      case F_SETLKW64:
            if (copy_from_user(&user, (struct oabi_flock64 __user *)arg,
                           sizeof(user)))
                  return -EFAULT;
            kernel.l_type     = user.l_type;
            kernel.l_whence   = user.l_whence;
            kernel.l_start    = user.l_start;
            kernel.l_len      = user.l_len;
            kernel.l_pid      = user.l_pid;
            local_arg = (unsigned long)&kernel;
            fs = get_fs();
            set_fs(KERNEL_DS);
      }

      ret = sys_fcntl64(fd, cmd, local_arg);

      switch (cmd) {
      case F_GETLK64:
            if (!ret) {
                  user.l_type = kernel.l_type;
                  user.l_whence     = kernel.l_whence;
                  user.l_start      = kernel.l_start;
                  user.l_len  = kernel.l_len;
                  user.l_pid  = kernel.l_pid;
                  if (copy_to_user((struct oabi_flock64 __user *)arg,
                               &user, sizeof(user)))
                        ret = -EFAULT;
            }
      case F_SETLK64:
      case F_SETLKW64:
            set_fs(fs);
      }

      return ret;
}

struct oabi_epoll_event {
      __u32 events;
      __u64 data;
} __attribute__ ((packed,aligned(4)));

asmlinkage long sys_oabi_epoll_ctl(int epfd, int op, int fd,
                           struct oabi_epoll_event __user *event)
{
      struct oabi_epoll_event user;
      struct epoll_event kernel;
      mm_segment_t fs;
      long ret;

      if (op == EPOLL_CTL_DEL)
            return sys_epoll_ctl(epfd, op, fd, NULL);
      if (copy_from_user(&user, event, sizeof(user)))
            return -EFAULT;
      kernel.events = user.events;
      kernel.data   = user.data;
      fs = get_fs();
      set_fs(KERNEL_DS);
      ret = sys_epoll_ctl(epfd, op, fd, &kernel);
      set_fs(fs);
      return ret;
}

asmlinkage long sys_oabi_epoll_wait(int epfd,
                            struct oabi_epoll_event __user *events,
                            int maxevents, int timeout)
{
      struct epoll_event *kbuf;
      mm_segment_t fs;
      long ret, err, i;

      if (maxevents <= 0 || maxevents > (INT_MAX/sizeof(struct epoll_event)))
            return -EINVAL;
      kbuf = kmalloc(sizeof(*kbuf) * maxevents, GFP_KERNEL);
      if (!kbuf)
            return -ENOMEM;
      fs = get_fs();
      set_fs(KERNEL_DS);
      ret = sys_epoll_wait(epfd, kbuf, maxevents, timeout);
      set_fs(fs);
      err = 0;
      for (i = 0; i < ret; i++) {
            __put_user_error(kbuf[i].events, &events->events, err);
            __put_user_error(kbuf[i].data,   &events->data,   err);
            events++;
      }
      kfree(kbuf);
      return err ? -EFAULT : ret;
}

struct oabi_sembuf {
      unsigned short    sem_num;
      short       sem_op;
      short       sem_flg;
      unsigned short    __pad;
};

asmlinkage long sys_oabi_semtimedop(int semid,
                            struct oabi_sembuf __user *tsops,
                            unsigned nsops,
                            const struct timespec __user *timeout)
{
      struct sembuf *sops;
      struct timespec local_timeout;
      long err;
      int i;

      if (nsops < 1)
            return -EINVAL;
      sops = kmalloc(sizeof(*sops) * nsops, GFP_KERNEL);
      if (!sops)
            return -ENOMEM;
      err = 0;
      for (i = 0; i < nsops; i++) {
            __get_user_error(sops[i].sem_num, &tsops->sem_num, err);
            __get_user_error(sops[i].sem_op,  &tsops->sem_op,  err);
            __get_user_error(sops[i].sem_flg, &tsops->sem_flg, err);
            tsops++;
      }
      if (timeout) {
            /* copy this as well before changing domain protection */
            err |= copy_from_user(&local_timeout, timeout, sizeof(*timeout));
            timeout = &local_timeout;
      }
      if (err) {
            err = -EFAULT;
      } else {
            mm_segment_t fs = get_fs();
            set_fs(KERNEL_DS);
            err = sys_semtimedop(semid, sops, nsops, timeout);
            set_fs(fs);
      }
      kfree(sops);
      return err;
}

asmlinkage long sys_oabi_semop(int semid, struct oabi_sembuf __user *tsops,
                         unsigned nsops)
{
      return sys_oabi_semtimedop(semid, tsops, nsops, NULL);
}

extern asmlinkage int sys_ipc(uint call, int first, int second, int third,
                        void __user *ptr, long fifth);

asmlinkage int sys_oabi_ipc(uint call, int first, int second, int third,
                      void __user *ptr, long fifth)
{
      switch (call & 0xffff) {
      case SEMOP:
            return  sys_oabi_semtimedop(first,
                                  (struct oabi_sembuf __user *)ptr,
                                  second, NULL);
      case SEMTIMEDOP:
            return  sys_oabi_semtimedop(first,
                                  (struct oabi_sembuf __user *)ptr,
                                  second,
                                  (const struct timespec __user *)fifth);
      default:
            return sys_ipc(call, first, second, third, ptr, fifth);
      }
}

asmlinkage long sys_oabi_bind(int fd, struct sockaddr __user *addr, int addrlen)
{
      sa_family_t sa_family;
      if (addrlen == 112 &&
          get_user(sa_family, &addr->sa_family) == 0 &&
          sa_family == AF_UNIX)
                  addrlen = 110;
      return sys_bind(fd, addr, addrlen);
}

asmlinkage long sys_oabi_connect(int fd, struct sockaddr __user *addr, int addrlen)
{
      sa_family_t sa_family;
      if (addrlen == 112 &&
          get_user(sa_family, &addr->sa_family) == 0 &&
          sa_family == AF_UNIX)
                  addrlen = 110;
      return sys_connect(fd, addr, addrlen);
}

asmlinkage long sys_oabi_sendto(int fd, void __user *buff,
                        size_t len, unsigned flags,
                        struct sockaddr __user *addr,
                        int addrlen)
{
      sa_family_t sa_family;
      if (addrlen == 112 &&
          get_user(sa_family, &addr->sa_family) == 0 &&
          sa_family == AF_UNIX)
                  addrlen = 110;
      return sys_sendto(fd, buff, len, flags, addr, addrlen);
}

asmlinkage long sys_oabi_sendmsg(int fd, struct msghdr __user *msg, unsigned flags)
{
      struct sockaddr __user *addr;
      int msg_namelen;
      sa_family_t sa_family;
      if (msg &&
          get_user(msg_namelen, &msg->msg_namelen) == 0 &&
          msg_namelen == 112 &&
          get_user(addr, &msg->msg_name) == 0 &&
          get_user(sa_family, &addr->sa_family) == 0 &&
          sa_family == AF_UNIX)
      {
            /*
             * HACK ALERT: there is a limit to how much backward bending
             * we should do for what is actually a transitional
             * compatibility layer.  This already has known flaws with
             * a few ioctls that we don't intend to fix.  Therefore
             * consider this blatent hack as another one... and take care
             * to run for cover.  In most cases it will "just work fine".
             * If it doesn't, well, tough.
             */
            put_user(110, &msg->msg_namelen);
      }
      return sys_sendmsg(fd, msg, flags);
}

asmlinkage long sys_oabi_socketcall(int call, unsigned long __user *args)
{
      unsigned long r = -EFAULT, a[6];

      switch (call) {
      case SYS_BIND:
            if (copy_from_user(a, args, 3 * sizeof(long)) == 0)
                  r = sys_oabi_bind(a[0], (struct sockaddr __user *)a[1], a[2]);
            break;
      case SYS_CONNECT:
            if (copy_from_user(a, args, 3 * sizeof(long)) == 0)
                  r = sys_oabi_connect(a[0], (struct sockaddr __user *)a[1], a[2]);
            break;
      case SYS_SENDTO:
            if (copy_from_user(a, args, 6 * sizeof(long)) == 0)
                  r = sys_oabi_sendto(a[0], (void __user *)a[1], a[2], a[3],
                                  (struct sockaddr __user *)a[4], a[5]);
            break;
      case SYS_SENDMSG:
            if (copy_from_user(a, args, 3 * sizeof(long)) == 0)
                  r = sys_oabi_sendmsg(a[0], (struct msghdr __user *)a[1], a[2]);
            break;
      default:
            r = sys_socketcall(call, args);
      }

      return r;
}

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