用于上传和查看图片的 Amazon S3 存储桶策略

Question

我有一个应用程序，用户可以使用 facebook 登录，然后可以将图像上传到 s3 存储桶并查看它们。我使用 Cognito 服务允许每个登录用户上传和查看所有文件。

我不知道如何在 s3 存储桶上设置正确的权限。这是我的尝试，但我无法保存政策并获得 Statement is missing required element - Statement "NO_ID-0" is missing "Principal" element

{
    "Version": "2012-10-17",
    "Id": "Policy1457546546214",
    "Statement": [
        {
            "Sid": "Stmt1475657256771436",
            "Effect": "Allow",
            "Principal": "*",
            "Action": "s3:GetObject",
            "Resource": "arn:aws:s3:::bucket-name/*"
        },
        {
            "Sid": "Stmt16577654572138125",
            "Effect": "Allow",
            "Principal": "*",
            "Action": "s3:PutObject",
            "Resource": [
                "bucket-name/identity-pool-id*"
            ]
        }
    ]
}

这是客户端部分，如果有帮助：

FB.login(function (response) {
    if (response.authResponse) {

      AWS.config.region = 'eu-west-1';
      AWS.config.credentials = new AWS.CognitoIdentityCredentials({
        IdentityPoolId: 'eu-west-1:xxxxxxxxxxx',
        Logins: {
          'graph.facebook.com': response.authResponse.accessToken
        }
      })

      var bucket = new AWS.S3({params: {Bucket: 'name'}})
      var fileChooser = document.getElementById('file-chooser')
      var button = document.getElementById('upload-button')

      button.addEventListener('click', function() {
        var file = fileChooser.files[0]
        var params = {Key: file.name, ContentType: file.type, Body: file}
        bucket.upload(params, function (err, data) {
        ...

认知 IAM > Roles > Cognito_myappAuth_Role:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Action": [
                "cognito-identity:*"
            ],
            "Effect": "Allow",
            "Resource": [
                "*"
            ]
        },
        {
            "Effect": "Allow",
            "Action": [
                "s3:GetObject",
                "s3:PutObject",
                "s3:PutObjectAcl"
            ],
            "Resource": [
                "arn:aws:s3:::bucket/${cognito-identity.amazonaws.com:sub}/*",
                "arn:aws:s3:::bucket/${cognito-identity.amazonaws.com:sub}"
            ]
        }
    ]
}

Answer 1

你检查过this blog post了吗？它有一个很好的示例，说明如何设置允许用户访问 S3 存储桶的角色。删除列表桶部分，您 link 对身份池角色的访问策略可能如下所示：

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Action": [
        "s3:GetObject",
        "s3:PutObject"
      ],
      "Effect": "Allow",
      "Resource": ["arn:aws:s3:::mybucket/${cognito-identity.amazonaws.com:sub}/*"]
    }
  ]
}

编辑：

Tl;dr 来自未来读者的评论：

将策略应用于池的身份验证角色而不是存储桶
如果应用程序用例需要公共区域，请使用存储桶根目录，否则为策略中定义的每个身份使用一个目录（如博客中所述）
角色本身只有在身份验证发生后才会应用。该策略仅定义了返回的凭据将有权执行的操作以及执行的操作。

用于上传和查看图片的 Amazon S3 存储桶策略

Amazon S3 bucket policy for uploading and viewing pictures

policy

amazon-s3

amazon-web-services

amazon-cognito