mirror of
https://github.com/opencontainers/runc.git
synced 2026-07-11 06:03:57 +08:00
Kir Kolyshkin
28cb321887
A lot of filesystem-related stuff happens inside the container root directory, and we have used its name before. It makes sense to pre-open it and use a *os.File handle instead. Function names in internal/pathrs are kept as is for simplicity (and it is an internal package), but they now accept root as *os.File. Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
73 lines
2.7 KiB
Go
73 lines
2.7 KiB
Go
// SPDX-License-Identifier: Apache-2.0
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/*
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* Copyright (C) 2024-2025 Aleksa Sarai <cyphar@cyphar.com>
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* Copyright (C) 2024-2025 SUSE LLC
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*
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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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*
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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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*/
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package pathrs
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import (
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"fmt"
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"os"
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"github.com/cyphar/filepath-securejoin/pathrs-lite"
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"github.com/sirupsen/logrus"
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)
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// MkdirAllInRoot attempts to make
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//
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// path, _ := securejoin.SecureJoin(root.Name(), unsafePath)
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// os.MkdirAll(path, mode)
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// os.Open(path)
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//
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// safer against attacks where components in the path are changed between
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// SecureJoin returning and MkdirAll (or Open) being called. In particular, we
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// try to detect any symlink components in the path while we are doing the
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// MkdirAll.
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//
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// NOTE: If unsafePath is a subpath of root, we assume that you have already
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// called SecureJoin and so we use the provided path verbatim without resolving
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// any symlinks (this is done in a way that avoids symlink-exchange races).
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// This means that the path also must not contain ".." elements, otherwise an
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// error will occur.
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//
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// This uses (pathrs-lite).MkdirAllHandle under the hood, but it has special
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// handling if unsafePath has already been scoped within the rootfs (this is
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// needed for a lot of runc callers and fixing this would require reworking a
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// lot of path logic).
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func MkdirAllInRoot(root *os.File, unsafePath string, mode os.FileMode) (*os.File, error) {
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unsafePath, err := hallucinateUnsafePath(root.Name(), unsafePath)
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if err != nil {
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return nil, fmt.Errorf("failed to construct hallucinated target path: %w", err)
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}
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// Check for any silly mode bits.
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if mode&^0o7777 != 0 {
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return nil, fmt.Errorf("tried to include non-mode bits in MkdirAll mode: 0o%.3o", mode)
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}
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// Linux (and thus os.MkdirAll) silently ignores the suid and sgid bits if
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// passed. While it would make sense to return an error in that case (since
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// the user has asked for a mode that won't be applied), for compatibility
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// reasons we have to ignore these bits.
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if ignoredBits := mode &^ 0o1777; ignoredBits != 0 {
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logrus.Warnf("MkdirAll called with no-op mode bits that are ignored by Linux: 0o%.3o", ignoredBits)
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mode &= 0o1777
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}
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return retryEAGAIN(func() (*os.File, error) {
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return pathrs.MkdirAllHandle(root, unsafePath, mode)
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})
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}
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