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77 lines
2.3 KiB
Go
77 lines
2.3 KiB
Go
//
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// Copyright 2019 Kinvolk
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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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// source: https://github.com/kinvolk/seccompagent/blob/main/pkg/readarg/readarg.go
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package readarg
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import (
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"bytes"
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"errors"
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"fmt"
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"os"
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"golang.org/x/sys/unix"
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)
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// OpenMem opens the memory file for the target process. It is done separately,
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// so that the caller can call libseccomp.NotifIDValid() in between.
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func OpenMem(pid uint32) (*os.File, error) {
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if pid == 0 {
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// This can happen if the seccomp agent is in a pid namespace
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// where the target pid is not mapped.
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return nil, errors.New("unknown pid")
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}
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return os.OpenFile(fmt.Sprintf("/proc/%d/mem", pid), os.O_RDONLY, 0)
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}
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func ReadString(memFile *os.File, offset int64) (string, error) {
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if offset == 0 {
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return "", nil
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}
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var buffer = make([]byte, 4096) // PATH_MAX
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_, err := unix.Pread(int(memFile.Fd()), buffer, offset)
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if err != nil {
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return "", err
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}
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// pread() will always return the size of the buffer, as usually
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// /proc/pid/mem is bigger than the buffer.
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// Then, to know when the string we are looking for finishes, we look
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// for the first \0 (with :bytes.IndexByte(buffer, 0)). As the string
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// should be nul-terminated, this is a simple way to find it.
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// Also, as a safety check, we add a ending 0 in the buffer, to avoid
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// doing buffer[-1] and panic, if the buffer doesn't contain any 0.
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buffer[len(buffer)-1] = 0
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s := buffer[:bytes.IndexByte(buffer, 0)]
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return string(s), nil
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}
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func ReadBytes(memFile *os.File, offset int64, len int) ([]byte, error) {
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if offset == 0 && len == 0 {
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return nil, nil
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}
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var buffer = make([]byte, len)
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// pread() will always return the size of the buffer
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_, err := unix.Pread(int(memFile.Fd()), buffer, offset)
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if err != nil {
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return nil, err
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}
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return buffer, nil
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}
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