jschoubben
5d98bcc0db
mesh/delivery-group group feat/900-node-files checking: composed check out of date: novox/mesh-controller@210f7cf5e64b was judged against trunk 611e2275cf7c, t…
mesh/merge-gate out of date: judged against trunk 3db85a0dde83, the trunk is now 8b53a3663244; judged again on a recheck or when it is merged
mesh/repo-check out of date: judged against trunk 3db85a0dde83, the trunk is now 8b53a3663244; judged again on a recheck or when it is merged
mesh/delivery superseded: a newer head of the same pull request
75 lines
2.1 KiB
Go
75 lines
2.1 KiB
Go
package main
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import (
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"bytes"
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"context"
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"fmt"
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"io"
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"os/exec"
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"sort"
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"strings"
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"time"
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)
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// Root repeats an act with more rights than the account this runs as has (novox/hq ADR 0394 §2). It is an
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// interface so a unit test uses a fake: no test runs sudo.
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type Root interface {
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// Run runs one fixed binary with the arguments given, never through a shell, and answers what it wrote.
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Run(bin string, args ...string) ([]byte, error)
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}
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// rootBins are the only binaries that run as root. The argument list is the caller's, but each caller in this
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// module builds it from fixed words and one path, and ends its options with `--`.
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var rootBins = map[string]bool{
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"/usr/bin/cat": true, "/usr/bin/cp": true, "/usr/bin/mv": true, "/usr/bin/stat": true, "/usr/bin/chmod": true,
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"/usr/bin/chown": true, "/usr/bin/mkdir": true, "/usr/bin/rm": true, "/usr/bin/readlink": true, "/usr/bin/find": true,
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}
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func rootBinList() string {
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var l []string
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for b := range rootBins {
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l = append(l, b)
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}
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sort.Strings(l)
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return strings.Join(l, ", ")
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}
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// sudoRoot is the real runner: `sudo -n` (never a password prompt) with a binary from rootBins.
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type sudoRoot struct{}
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// capped keeps at most n bytes and drops the rest.
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type capped struct {
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buf bytes.Buffer
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n int
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}
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func (c *capped) Write(p []byte) (int, error) {
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if room := c.n - c.buf.Len(); room > 0 {
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if len(p) < room {
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room = len(p)
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}
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c.buf.Write(p[:room])
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}
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return len(p), nil
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}
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func (sudoRoot) Run(bin string, args ...string) ([]byte, error) {
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if !rootBins[bin] {
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return nil, fmt.Errorf("%s is not one of the binaries that run as root here (%s)", bin, rootBinList())
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}
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ctx, cancel := context.WithTimeout(context.Background(), SearchTime+10*time.Second)
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defer cancel()
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cmd := exec.CommandContext(ctx, "/usr/bin/sudo", append([]string{"-n", "--", bin}, args...)...)
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out, errs := &capped{n: MaxScan}, &capped{n: 4096}
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cmd.Stdout, cmd.Stderr = out, errs
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cmd.Stdin = io.LimitReader(strings.NewReader(""), 0)
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if err := cmd.Run(); err != nil {
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msg := strings.TrimSpace(errs.buf.String())
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if msg == "" {
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msg = err.Error()
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}
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return nil, fmt.Errorf("sudo -n %s: %s", bin, msg)
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}
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return out.buf.Bytes(), nil
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}
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