statx: optimize copy of struct statx to userspace

[linux-block.git] / fs / stat.c

diff --git a/fs/stat.c b/fs/stat.c
index b792dd201c31986a65c4b627b7b1ec300d61b3db..ab27f2868588b89a9408e9c1192c34571daeab2b 100644 (file)
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -510,46 +510,37 @@ SYSCALL_DEFINE4(fstatat64, int, dfd, const char __user *, filename,
 }
 #endif /* __ARCH_WANT_STAT64 || __ARCH_WANT_COMPAT_STAT64 */
 
-static inline int __put_timestamp(struct timespec *kts,
-                                 struct statx_timestamp __user *uts)
+static noinline_for_stack int
+cp_statx(const struct kstat *stat, struct statx __user *buffer)
 {
-       return (__put_user(kts->tv_sec,         &uts->tv_sec            ) ||
-               __put_user(kts->tv_nsec,        &uts->tv_nsec           ) ||
-               __put_user(0,                   &uts->__reserved        ));
-}
-
-/*
- * Set the statx results.
- */
-static long statx_set_result(struct kstat *stat, struct statx __user *buffer)
-{
-       uid_t uid = from_kuid_munged(current_user_ns(), stat->uid);
-       gid_t gid = from_kgid_munged(current_user_ns(), stat->gid);
-
-       if (__put_user(stat->result_mask,       &buffer->stx_mask       ) ||
-           __put_user(stat->mode,              &buffer->stx_mode       ) ||
-           __clear_user(&buffer->__spare0, sizeof(buffer->__spare0))     ||
-           __put_user(stat->nlink,             &buffer->stx_nlink      ) ||
-           __put_user(uid,                     &buffer->stx_uid        ) ||
-           __put_user(gid,                     &buffer->stx_gid        ) ||
-           __put_user(stat->attributes,        &buffer->stx_attributes ) ||
-           __put_user(stat->blksize,           &buffer->stx_blksize    ) ||
-           __put_user(MAJOR(stat->rdev),       &buffer->stx_rdev_major ) ||
-           __put_user(MINOR(stat->rdev),       &buffer->stx_rdev_minor ) ||
-           __put_user(MAJOR(stat->dev),        &buffer->stx_dev_major  ) ||
-           __put_user(MINOR(stat->dev),        &buffer->stx_dev_minor  ) ||
-           __put_timestamp(&stat->atime,       &buffer->stx_atime      ) ||
-           __put_timestamp(&stat->btime,       &buffer->stx_btime      ) ||
-           __put_timestamp(&stat->ctime,       &buffer->stx_ctime      ) ||
-           __put_timestamp(&stat->mtime,       &buffer->stx_mtime      ) ||
-           __put_user(stat->ino,               &buffer->stx_ino        ) ||
-           __put_user(stat->size,              &buffer->stx_size       ) ||
-           __put_user(stat->blocks,            &buffer->stx_blocks     ) ||
-           __clear_user(&buffer->__spare1, sizeof(buffer->__spare1))     ||
-           __clear_user(&buffer->__spare2, sizeof(buffer->__spare2)))
-               return -EFAULT;
-
-       return 0;
+       struct statx tmp;
+
+       memset(&tmp, 0, sizeof(tmp));
+
+       tmp.stx_mask = stat->result_mask;
+       tmp.stx_blksize = stat->blksize;
+       tmp.stx_attributes = stat->attributes;
+       tmp.stx_nlink = stat->nlink;
+       tmp.stx_uid = from_kuid_munged(current_user_ns(), stat->uid);
+       tmp.stx_gid = from_kgid_munged(current_user_ns(), stat->gid);
+       tmp.stx_mode = stat->mode;
+       tmp.stx_ino = stat->ino;
+       tmp.stx_size = stat->size;
+       tmp.stx_blocks = stat->blocks;
+       tmp.stx_atime.tv_sec = stat->atime.tv_sec;
+       tmp.stx_atime.tv_nsec = stat->atime.tv_nsec;
+       tmp.stx_btime.tv_sec = stat->btime.tv_sec;
+       tmp.stx_btime.tv_nsec = stat->btime.tv_nsec;
+       tmp.stx_ctime.tv_sec = stat->ctime.tv_sec;
+       tmp.stx_ctime.tv_nsec = stat->ctime.tv_nsec;
+       tmp.stx_mtime.tv_sec = stat->mtime.tv_sec;
+       tmp.stx_mtime.tv_nsec = stat->mtime.tv_nsec;
+       tmp.stx_rdev_major = MAJOR(stat->rdev);
+       tmp.stx_rdev_minor = MINOR(stat->rdev);
+       tmp.stx_dev_major = MAJOR(stat->dev);
+       tmp.stx_dev_minor = MINOR(stat->dev);
+
+       return copy_to_user(buffer, &tmp, sizeof(tmp)) ? -EFAULT : 0;
 }
 
 /**
@@ -573,8 +564,6 @@ SYSCALL_DEFINE5(statx,
 
        if ((flags & AT_STATX_SYNC_TYPE) == AT_STATX_SYNC_TYPE)
                return -EINVAL;
-       if (!access_ok(VERIFY_WRITE, buffer, sizeof(*buffer)))
-               return -EFAULT;
 
        if (filename)
                error = vfs_statx(dfd, filename, flags, &stat, mask);
@@ -582,7 +571,8 @@ SYSCALL_DEFINE5(statx,
                error = vfs_statx_fd(dfd, &stat, mask, flags);
        if (error)
                return error;
-       return statx_set_result(&stat, buffer);
+
+       return cp_statx(&stat, buffer);
 }
 
 /* Caller is here responsible for sufficient locking (ie. inode->i_lock) */