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https://github.com/versity/versitygw.git
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niksis02
c84c5f645a
Bucket policy `Principal` named callers by access key id. Under the standalone IAM service it now names them by AWS-style ARN, as real S3 does: a user ARN, a role ARN (covering every session of that role), an assumed-role ARN (covering one session), the account root ARN or bare account id, or `*`. Every other IAM backend has no ARNs to name anything by and keeps access-key principals unchanged, gated on a new `auth.PrincipalResolver` capability interface that only the standalone client implements. `auth.Account` carries `Arn` and `RoleArn`, filled at authentication time, so a session can be matched against both its own ARN and its role's. Principals are validated at PutBucketPolicy time through a new `/private/resolve-principals` endpoint, which rejects anything that does not name a live identity with `MalformedPolicy: Invalid principal in policy`. An `Allow` naming the account root ARN or bare account id delegates to the account's own IAM rather than granting on its own, while a `Deny` naming it denies every principal in the account outright. Denial messages now name the caller by ARN wherever one exists. Also fixes `aws:PrincipalArn` for assumed-role sessions, which reported the session ARN where AWS reports the role's, and stops an unreachable IAM service being reported as a malformed policy.
68 lines
2.8 KiB
Go
68 lines
2.8 KiB
Go
// Copyright 2026 Versity Software
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// This file is licensed under the Apache License, Version 2.0
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// (the "License"); you may not use this file except in compliance
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// with the License. You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package auth
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// FixedBucketOwner is implemented by IAM backends that give every bucket the
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// same owner instead of the account that created it — currently only the
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// standalone IAM service client, which has no per-user ownership to express:
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// every account is a plain RoleUser, they cannot be enumerated, and access is
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// decided by IAM policy rather than by ACL.
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//
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// Backends that do not implement it keep per-creator ownership as before.
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type FixedBucketOwner interface {
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BucketOwner() Account
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}
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// ResolveFixedBucketOwner reports the account that owns every bucket when iam
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// fixes ownership, and false when ownership follows the creator instead.
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func ResolveFixedBucketOwner(iam IAMService) (Account, bool) {
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fbo, ok := iam.(FixedBucketOwner)
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if !ok {
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return Account{}, false
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}
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return fbo.BucketOwner(), true
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}
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// rootIdentity returns the account a storage backend should see for a request
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// signed with the gateway's root credentials. The S3 request path knows root
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// only by its access key and secret, so root would otherwise reach the
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// backend with the zero uid/gid — which the posix backend's --chuid/--chgid
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// then tries to chown to, an operation an unprivileged gateway can never
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// perform.
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//
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// An IAM backend that fixes bucket ownership to root also defines the POSIX
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// identity root owns those buckets with, so take it from there: root's own
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// object writes then land with the same ownership as the buckets root owns.
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// Backends that do not fix ownership resolve a real per-account uid/gid for
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// every other account and keep root exactly as it was.
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//
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// The same backend is also the one that knows root's principal ARN, which
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// the S3 request path likewise cannot derive: root is the only identity
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// resolved locally rather than through the IAM service, so without this it
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// would reach bucket-policy matching unnamed and a statement naming the
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// account root ARN would miss it.
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func rootIdentity(iam IAMService, root Account) Account {
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owner, fixed := ResolveFixedBucketOwner(iam)
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if !fixed || owner.Access != root.Access {
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return root
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}
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root.UserID = owner.UserID
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root.GroupID = owner.GroupID
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root.ProjectID = owner.ProjectID
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root.Arn = owner.Arn
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return root
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}
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