// SPDX-License-Identifier: GPL-2.0-only
/*
 *  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.
 */

/*
 * 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/cred.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 <linux/uaccess.h>
#include <linux/slab.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 = from_kuid_munged(current_user_ns(), stat->uid);
        tmp.st_gid = from_kgid_munged(current_user_ns(), 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(const 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(const 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,
                                   const char __user *filename,
                                   struct oldabi_stat64  __user *statbuf,
                                   int flag)
{
        struct kstat stat;
        int error;

        error = vfs_fstatat(dfd, filename, &stat, flag);
        if (error)
                return error;
        return cp_oldabi_stat64(&stat, statbuf);
}

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)));

static long do_locks(unsigned int fd, unsigned int cmd,
                                 unsigned long arg)
{
        struct flock64 kernel;
        struct oabi_flock64 user;
        mm_segment_t fs;
        long ret;

        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;

        fs = get_fs();
        set_fs(KERNEL_DS);
        ret = sys_fcntl64(fd, cmd, (unsigned long)&kernel);
        set_fs(fs);

        if (!ret && (cmd == F_GETLK64 || cmd == F_OFD_GETLK)) {
                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;
        }
        return ret;
}

asmlinkage long sys_oabi_fcntl64(unsigned int fd, unsigned int cmd,
                                 unsigned long arg)
{
        switch (cmd) {
        case F_OFD_GETLK:
        case F_OFD_SETLK:
        case F_OFD_SETLKW:
        case F_GETLK64:
        case F_SETLK64:
        case F_SETLKW64:
                return do_locks(fd, cmd, arg);

        default:
                return sys_fcntl64(fd, cmd, arg);
        }
}

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;

        if (ep_op_has_event(op) &&
            copy_from_user(&user, event, sizeof(user)))
                return -EFAULT;

        kernel.events = user.events;
        kernel.data   = user.data;

        return do_epoll_ctl(epfd, op, fd, &kernel, false);
}

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

        if (maxevents <= 0 ||
                        maxevents > (INT_MAX/sizeof(*kbuf)) ||
                        maxevents > (INT_MAX/sizeof(*events)))
                return -EINVAL;
        if (!access_ok(events, sizeof(*events) * maxevents))
                return -EFAULT;
        kbuf = kmalloc_array(maxevents, sizeof(*kbuf), 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++) {
                e.events = kbuf[i].events;
                e.data = kbuf[i].data;
                err = __copy_to_user(events, &e, sizeof(e));
                if (err)
                        break;
                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 old_timespec32 __user *timeout)
{
        struct sembuf *sops;
        struct old_timespec32 local_timeout;
        long err;
        int i;

        if (nsops < 1 || nsops > SEMOPM)
                return -EINVAL;
        if (!access_ok(tsops, sizeof(*tsops) * nsops))
                return -EFAULT;
        sops = kmalloc_array(nsops, sizeof(*sops), GFP_KERNEL);
        if (!sops)
                return -ENOMEM;
        err = 0;
        for (i = 0; i < nsops; i++) {
                struct oabi_sembuf osb;
                err |= __copy_from_user(&osb, tsops, sizeof(osb));
                sops[i].sem_num = osb.sem_num;
                sops[i].sem_op = osb.sem_op;
                sops[i].sem_flg = osb.sem_flg;
                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_time32(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);
}

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 old_timespec32 __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 user_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 user_msghdr __user *)a[1], a[2]);
                break;
        default:
                r = sys_socketcall(call, args);
        }

        return r;
}