IAM policy can be used to give readonly access to a single S3 bucket in Amazon cloud for a particular user.
{
"Statement": [
{
"Action": [
"s3:GetBucketAcl",
"s3:GetBucketLocation",
"s3:GetBucketNotification",
"s3:GetBucketPolicy",
"s3:GetBucketRequestPayment",
"s3:GetBucketVersioning",
"s3:GetObject",
"s3:GetObjectAcl",
"s3:GetObjectVersion",
"s3:GetObjectVersionAcl",
"s3:ListBucket",
"s3:ListBucketMultipartUploads",
"s3:ListBucketVersions",
"s3:ListMultipartUploadParts"
],
"Effect": "Allow",
"Resource": [
"arn:aws:s3:::BUCKET_NAME",
"arn:aws:s3:::BUCKET_NAME/*"
]
}
]
}