I keep seeing posts that refer to setting a policy and while they mention S3 buckets the policy they are often referring to are IAM policies.
In my case I want to control access to my S3 bucket only by an actual "S3 bucket policy".
My current path is :::mybucket, which has /thing1/ and /thing2/
If I wanted a bucket policy that allows a CLI user the ability to list and get /thing1/* but not /thing2/* how would this be done? I've tried my policy with all kinds of conditions, paths etc but nothing seems to work...
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I have an S3 bucket, and I want to know which AWS resources have permission to access it (security audit). There is nothing in the bucket policy itself - permissions are defined using IAM policies on the resources.
I have a LOT of different components on this project. Is there a way to find all the resources that have permissions for this bucket? Or do I have to check the IAM policies on every single resource in the account?
I always get confused in two but I wanted to add a IAM policy on S3 bucket.
Basically I have created an output bucket for Amazon transcriptions but it seems I need to add IAM role to allow Transcription job to write to the bucket. I think if I can attach AmazonTranscribeFullAccess to S3 bucket, it will work but I am unable to attach this policy. Could you please advise how can I add this policy on the new bucket?
There are a few concepts you will want to dig deeper into to understand the difference between IAM policies and S3 bucket policies. A detailed guide is: https://docs.aws.amazon.com/AmazonS3/latest/dev/how-s3-evaluates-access-control.html
You can attach IAM policies to Users, Groups and Roles, and you can attach bucket policies to S3 buckets.
Try adding S3 access to the user/role that you are using to run the transcribe job.
I have been reading a number of docs and watched number of videos, but I am still very confused about IAM Roles and Bucket policies. Here is what confuses me:
1) I create a bucket. At that time I can make it public or keep it private. If I make it public, then anyone, or any Application, can "see" the objects in the bucket. I think the permissions can be set to add/delete/get/list objects in the bucket. If this is the case, then why do I ever need to add any IAM Role for S3 buckets, or, add any Bucket policy (???)
2) At the time I create a bucket, can I give very specific permissions to only certain users/applications/EC2 instances etc to all or part of the bucket? e.g. App1 on EC2-X can access subfolder A in bucket B1.
3) Coming to IAM Roles, an EC2 role that gives full S3 access- what does it mean? Full access to any bucket? How can I restrict an app running on an EC2 to only certain buckets, with only certain restricted permissions (see #2) above)? Do all Apps on the EC2 have full access to all buckets? At the time of creating a bucket, can the permissions be so set that an IAM Role can be overruled?
4) Finally, what do Bucket Policies do in addition to the above IAM Roles? e.g is 'AllowS3FullAccess' a "Bucket Policy", or an "IAM Policy"? Why differentiate between types of policies- policies are just that- they define some permissions/rules on some objects/resources,as I see it.
Thanks for any clarifications.
- a newcomer to AWS
I think you are confusing permissions for resources with IAM entities.
i) There are resources (S3 bucket, EC2 instances etc.) owned by the AWS account and these resources can be accessed by IAM users, IAM roles or other AWS Services (can be from same or different account)
ii) We manage who can access and their permission level with policies
iii) Policies can be identity based (attached to IAM user/group/role) or resource based (attached to S3 bucket, SNS topic)
iv) Resource based policy will have a Principal element but the identity based policies will not have that (because the attached IAM entity is the Principal)
v) Permissions start from default deny, allow overrides the default deny and an explicit deny overrides any allow
vi) Final access will be determined by combination of all policies
To answer your questions:
1> We cannot add (or attach) an IAM role with an S3 bucket. If you want your bucket should be public (which is not recommended but need to do it till some extent if it's in use for static website), then you can keep it public
2> It is not possible while creating the bucket. You have to do it after creating the bucket via IAM and/or S3 bucket policy
3> If an IAM role has AmazonS3FullAccess, the role can (Effect:Allow) call any S3 API (s3:) for any S3 resource (Resource:) in your account (provided they don't have cross account access).
If multiple applications run on an instance with an IAM role attached and are using credentials provided by the role, their permission will be same.
4> I don't know where you got the reference AllowS3FullAccess but we cannot confirm unless we know the exact JSON. If it is attached to a bucket or has the Principal element, it is a bucket policy.
You can use IAM and Bucket policies based on your need. Usually bucket policies are used for cross account access or if you want to manage S3 permission policies in a single place.
I was trying few things with aws s3 bucket policy and the documentation for put-bucket-policy says that the user should have PutBucketPolicy on the bucket and should be the owner.
I do not understand the use of PutBucketPolicy permission then.
Also is the bucket owner given a default PutBucketPolicy permission on his bucket?
http://docs.aws.amazon.com/AmazonS3/latest/API/RESTBucketPUTpolicy.html
The confusion here, I suspect, is related to the fact that users don't own buckets. The "owner" of a bucket is an individual AWS account.
You can't successfully grant PutBucketPolicy to any user in a different AWS account -- only your own account's user(s).
There's an illusion of circular logic here: How can I set a bucket policy... allowing myself to set the bucket policy... unless I am already able to set the bucket policy... which would make it unnecessary to set a bucket policy allowing me to set the bucket policy?
This is not as it seems: the problem is resolved by the fact that IAM user policies can grant a user permission to set the bucket policy, and the root account can do this by default -- which is why you should not use your root account credentials routinely: they are too privileged, if they fall into the wrong hands.
In our S3 configuration we have a bucket that ended up without any permissions, which I reckon my colleague deleted.
Now, we cannot read this bucket, I cannot add permissions to it using the management console, selecting grantee and the permission, as it says "Sorry! You do not have permissions to view this bucket.", When I click on "Add Bucket policy", it opens the dialog which says "Loading" and it keeps loading forever.
I've tried to use aws s3 and aws s3api to grand permission and/or delete the bucket with no success.
I want to either delete this bucket or change it's permissions.
EDIT: We also noticed that the bucket has no owner.
In the Amazon S3 Management Console:
Select the bucket (don't click on its name, just click the line it is on)
Go to the Properties pane on the right
Expand the Permissions section
If there is no line displayed, click Add more permissions, then select the Grantee (possibly your account name?) and tick some permission boxes
These permissions are on the Bucket itself.
Permissions to list the contents of an Amazon S3 bucket are normally granted via Identity and Access Management (IAM) rather than a bucket policy. Traditionally, bucket policies are used to grant access to objects within a bucket.
From your description, it appears that there is no bucket policy in place, which is perfectly okay. All new buckets have no bucket policy anyway.
If the above fix doesn't work, you should check your permissions in IAM to see what you are permitted to do in Amazon S3:
Is there a policy granting you access to everything in S3 (s3:*), or at least a policy granting you access to this bucket?
Is there a policy that is explicitly denying access to this bucket? (Deny overrides Allow)