75 lines
2.0 KiB
Go
75 lines
2.0 KiB
Go
/*
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Copyright The containerd Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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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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*/
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package v2
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import (
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"encoding/json"
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"os"
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"github.com/opencontainers/runtime-spec/specs-go"
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)
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// prepareBundleDirectoryPermissions prepares the permissions of the bundle
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// directory according to the needs of the current platform.
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// On Linux when user namespaces are enabled, the permissions are modified to
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// allow the remapped root GID to access the bundle.
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func prepareBundleDirectoryPermissions(path string, spec []byte) error {
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gid, err := remappedGID(spec)
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if err != nil {
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return err
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}
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if gid == 0 {
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return nil
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}
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if err := os.Chown(path, -1, int(gid)); err != nil {
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return err
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}
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return os.Chmod(path, 0710)
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}
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// ociSpecUserNS is a subset of specs.Spec used to reduce garbage during
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// unmarshal.
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type ociSpecUserNS struct {
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Linux *linuxSpecUserNS
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}
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// linuxSpecUserNS is a subset of specs.Linux used to reduce garbage during
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// unmarshal.
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type linuxSpecUserNS struct {
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GIDMappings []specs.LinuxIDMapping
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}
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// remappedGID reads the remapped GID 0 from the OCI spec, if it exists. If
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// there is no remapping, remappedGID returns 0. If the spec cannot be parsed,
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// remappedGID returns an error.
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func remappedGID(spec []byte) (uint32, error) {
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var ociSpec ociSpecUserNS
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err := json.Unmarshal(spec, &ociSpec)
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if err != nil {
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return 0, err
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}
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if ociSpec.Linux == nil || len(ociSpec.Linux.GIDMappings) == 0 {
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return 0, nil
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}
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for _, mapping := range ociSpec.Linux.GIDMappings {
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if mapping.ContainerID == 0 {
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return mapping.HostID, nil
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}
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}
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return 0, nil
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}
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