// SPDX-License-Identifier: GPL-2.0
#include <linux/file.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/utime.h>
#include <linux/syscalls.h>
#include <linux/uaccess.h>
#include <linux/compat.h>
#include <asm/unistd.h>

static bool nsec_valid(long nsec)
{
        if (nsec == UTIME_OMIT || nsec == UTIME_NOW)
                return true;

        return nsec >= 0 && nsec <= 999999999;
}

static int utimes_common(const struct path *path, struct timespec64 *times)
{
        int error;
        struct iattr newattrs;
        struct inode *inode = path->dentry->d_inode;
        struct inode *delegated_inode = NULL;

        error = mnt_want_write(path->mnt);
        if (error)
                goto out;

        if (times && times[0].tv_nsec == UTIME_NOW &&
                     times[1].tv_nsec == UTIME_NOW)
                times = NULL;

        newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
        if (times) {
                if (times[0].tv_nsec == UTIME_OMIT)
                        newattrs.ia_valid &= ~ATTR_ATIME;
                else if (times[0].tv_nsec != UTIME_NOW) {
                        newattrs.ia_atime.tv_sec = times[0].tv_sec;
                        newattrs.ia_atime.tv_nsec = times[0].tv_nsec;
                        newattrs.ia_valid |= ATTR_ATIME_SET;
                }

                if (times[1].tv_nsec == UTIME_OMIT)
                        newattrs.ia_valid &= ~ATTR_MTIME;
                else if (times[1].tv_nsec != UTIME_NOW) {
                        newattrs.ia_mtime.tv_sec = times[1].tv_sec;
                        newattrs.ia_mtime.tv_nsec = times[1].tv_nsec;
                        newattrs.ia_valid |= ATTR_MTIME_SET;
                }
                /*
                 * Tell setattr_prepare(), that this is an explicit time
                 * update, even if neither ATTR_ATIME_SET nor ATTR_MTIME_SET
                 * were used.
                 */
                newattrs.ia_valid |= ATTR_TIMES_SET;
        } else {
                newattrs.ia_valid |= ATTR_TOUCH;
        }
retry_deleg:
        inode_lock(inode);
        error = notify_change(path->dentry, &newattrs, &delegated_inode);
        inode_unlock(inode);
        if (delegated_inode) {
                error = break_deleg_wait(&delegated_inode);
                if (!error)
                        goto retry_deleg;
        }

        mnt_drop_write(path->mnt);
out:
        return error;
}

/*
 * do_utimes - change times on filename or file descriptor
 * @dfd: open file descriptor, -1 or AT_FDCWD
 * @filename: path name or NULL
 * @times: new times or NULL
 * @flags: zero or more flags (only AT_SYMLINK_NOFOLLOW for the moment)
 *
 * If filename is NULL and dfd refers to an open file, then operate on
 * the file.  Otherwise look up filename, possibly using dfd as a
 * starting point.
 *
 * If times==NULL, set access and modification to current time,
 * must be owner or have write permission.
 * Else, update from *times, must be owner or super user.
 */
long do_utimes(int dfd, const char __user *filename, struct timespec64 *times,
               int flags)
{
        int error = -EINVAL;

        if (times && (!nsec_valid(times[0].tv_nsec) ||
                      !nsec_valid(times[1].tv_nsec))) {
                goto out;
        }

        if (flags & ~AT_SYMLINK_NOFOLLOW)
                goto out;

        if (filename == NULL && dfd != AT_FDCWD) {
                struct fd f;

                if (flags & AT_SYMLINK_NOFOLLOW)
                        goto out;

                f = fdget(dfd);
                error = -EBADF;
                if (!f.file)
                        goto out;

                error = utimes_common(&f.file->f_path, times);
                fdput(f);
        } else {
                struct path path;
                int lookup_flags = 0;

                if (!(flags & AT_SYMLINK_NOFOLLOW))
                        lookup_flags |= LOOKUP_FOLLOW;
retry:
                error = user_path_at(dfd, filename, lookup_flags, &path);
                if (error)
                        goto out;

                error = utimes_common(&path, times);
                path_put(&path);
                if (retry_estale(error, lookup_flags)) {
                        lookup_flags |= LOOKUP_REVAL;
                        goto retry;
                }
        }

out:
        return error;
}

SYSCALL_DEFINE4(utimensat, int, dfd, const char __user *, filename,
                struct __kernel_timespec __user *, utimes, int, flags)
{
        struct timespec64 tstimes[2];

        if (utimes) {
                if ((get_timespec64(&tstimes[0], &utimes[0]) ||
                        get_timespec64(&tstimes[1], &utimes[1])))
                        return -EFAULT;

                /* Nothing to do, we must not even check the path.  */
                if (tstimes[0].tv_nsec == UTIME_OMIT &&
                    tstimes[1].tv_nsec == UTIME_OMIT)
                        return 0;
        }

        return do_utimes(dfd, filename, utimes ? tstimes : NULL, flags);
}

#ifdef __ARCH_WANT_SYS_UTIME
/*
 * futimesat(), utimes() and utime() are older versions of utimensat()
 * that are provided for compatibility with traditional C libraries.
 * On modern architectures, we always use libc wrappers around
 * utimensat() instead.
 */
static long do_futimesat(int dfd, const char __user *filename,
                         struct timeval __user *utimes)
{
        struct timeval times[2];
        struct timespec64 tstimes[2];

        if (utimes) {
                if (copy_from_user(&times, utimes, sizeof(times)))
                        return -EFAULT;

                /* This test is needed to catch all invalid values.  If we
                   would test only in do_utimes we would miss those invalid
                   values truncated by the multiplication with 1000.  Note
                   that we also catch UTIME_{NOW,OMIT} here which are only
                   valid for utimensat.  */
                if (times[0].tv_usec >= 1000000 || times[0].tv_usec < 0 ||
                    times[1].tv_usec >= 1000000 || times[1].tv_usec < 0)
                        return -EINVAL;

                tstimes[0].tv_sec = times[0].tv_sec;
                tstimes[0].tv_nsec = 1000 * times[0].tv_usec;
                tstimes[1].tv_sec = times[1].tv_sec;
                tstimes[1].tv_nsec = 1000 * times[1].tv_usec;
        }

        return do_utimes(dfd, filename, utimes ? tstimes : NULL, 0);
}


SYSCALL_DEFINE3(futimesat, int, dfd, const char __user *, filename,
                struct timeval __user *, utimes)
{
        return do_futimesat(dfd, filename, utimes);
}

SYSCALL_DEFINE2(utimes, char __user *, filename,
                struct timeval __user *, utimes)
{
        return do_futimesat(AT_FDCWD, filename, utimes);
}

SYSCALL_DEFINE2(utime, char __user *, filename, struct utimbuf __user *, times)
{
        struct timespec64 tv[2];

        if (times) {
                if (get_user(tv[0].tv_sec, &times->actime) ||
                    get_user(tv[1].tv_sec, &times->modtime))
                        return -EFAULT;
                tv[0].tv_nsec = 0;
                tv[1].tv_nsec = 0;
        }
        return do_utimes(AT_FDCWD, filename, times ? tv : NULL, 0);
}
#endif

#ifdef CONFIG_COMPAT_32BIT_TIME
/*
 * Not all architectures have sys_utime, so implement this in terms
 * of sys_utimes.
 */
#ifdef __ARCH_WANT_SYS_UTIME32
SYSCALL_DEFINE2(utime32, const char __user *, filename,
                struct old_utimbuf32 __user *, t)
{
        struct timespec64 tv[2];

        if (t) {
                if (get_user(tv[0].tv_sec, &t->actime) ||
                    get_user(tv[1].tv_sec, &t->modtime))
                        return -EFAULT;
                tv[0].tv_nsec = 0;
                tv[1].tv_nsec = 0;
        }
        return do_utimes(AT_FDCWD, filename, t ? tv : NULL, 0);
}
#endif

SYSCALL_DEFINE4(utimensat_time32, unsigned int, dfd, const char __user *, filename, struct old_timespec32 __user *, t, int, flags)
{
        struct timespec64 tv[2];

        if  (t) {
                if (get_old_timespec32(&tv[0], &t[0]) ||
                    get_old_timespec32(&tv[1], &t[1]))
                        return -EFAULT;

                if (tv[0].tv_nsec == UTIME_OMIT && tv[1].tv_nsec == UTIME_OMIT)
                        return 0;
        }
        return do_utimes(dfd, filename, t ? tv : NULL, flags);
}

#ifdef __ARCH_WANT_SYS_UTIME32
static long do_compat_futimesat(unsigned int dfd, const char __user *filename,
                                struct old_timeval32 __user *t)
{
        struct timespec64 tv[2];

        if (t) {
                if (get_user(tv[0].tv_sec, &t[0].tv_sec) ||
                    get_user(tv[0].tv_nsec, &t[0].tv_usec) ||
                    get_user(tv[1].tv_sec, &t[1].tv_sec) ||
                    get_user(tv[1].tv_nsec, &t[1].tv_usec))
                        return -EFAULT;
                if (tv[0].tv_nsec >= 1000000 || tv[0].tv_nsec < 0 ||
                    tv[1].tv_nsec >= 1000000 || tv[1].tv_nsec < 0)
                        return -EINVAL;
                tv[0].tv_nsec *= 1000;
                tv[1].tv_nsec *= 1000;
        }
        return do_utimes(dfd, filename, t ? tv : NULL, 0);
}

SYSCALL_DEFINE3(futimesat_time32, unsigned int, dfd,
                       const char __user *, filename,
                       struct old_timeval32 __user *, t)
{
        return do_compat_futimesat(dfd, filename, t);
}

SYSCALL_DEFINE2(utimes_time32, const char __user *, filename, struct old_timeval32 __user *, t)
{
        return do_compat_futimesat(AT_FDCWD, filename, t);
}
#endif
#endif