signed-commit remote shell (see also https://github.com/dyne/scorsh)
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scorsh/commits.go

240 lines
6.2 KiB

package main
import (
"fmt"
"github.com/dyne/git2go.v26"
"golang.org/x/crypto/openpgp"
"gopkg.in/yaml.v2"
"log"
"os"
"strings"
// "log"
)
// func commitToString(commit *git.Commit) string {
// var ret string
// ret += fmt.Sprintf("type: %s\n", commit.Type())
// ret += fmt.Sprintf("Id: %s\n", commit.Id())
// ret += fmt.Sprintf("Author: %s\n", commit.Author())
// ret += fmt.Sprintf("Message: %s\n", commit.Message())
// ret += fmt.Sprintf("Parent-count: %d\n", commit.ParentCount())
// return ret
// }
// FIXME: RETURN THE ENTITY PROVIDED BY THE CHECK, OR nil
func checkSignature(commit *git.Commit, keyring *openpgp.KeyRing) (signature, signed string, err error) {
signature, signed, err = commit.ExtractSignature()
if err == nil {
_, errSig :=
openpgp.CheckArmoredDetachedSignature(*keyring, strings.NewReader(signed),
strings.NewReader(signature))
if errSig == nil {
debug.log("[commit: %s] Good signature \n", commit.Id())
return signature, signed, nil
}
err = errSig
}
return "", "", err
}
func findScorshMessage(commit *git.Commit) (*clientMsg, error) {
var commands = new(clientMsg)
sep := "---\n"
msg := commit.RawMessage()
debug.log("[findScorshMessage] found message:\n%s\n", msg)
// FIXME!!! replace the following with a proper regexp.Match
idx := strings.Index(msg, sep)
if idx < 0 {
return nil, fmt.Errorf("no SCORSH message found")
}
err := yaml.Unmarshal([]byte(msg[idx:]), &commands)
if err != nil {
// no scorsh message found
err = fmt.Errorf("unmarshal error: %s", err)
commands = nil
} else {
err = nil
}
return commands, nil
}
// return a list of keyring names which verify the signature of a given commit
func getValidKeys(commit *git.Commit, keys *map[string]openpgp.KeyRing) []string {
var ret []string
for kname, kval := range *keys {
_, _, err := checkSignature(commit, &kval)
if err == nil {
ret = append(ret, kname)
}
}
return ret
}
func intersectKeys(ref map[string]bool, keys []string) []string {
var ret []string
for _, k := range keys {
if _, ok := ref[k]; ok {
ret = append(ret, k)
}
}
return ret
}
func findCmdConfig(cmdName string, w *worker) (commandCfg, bool) {
var cmdNull commandCfg
for _, c := range w.Commands {
if c.Name == cmdName {
return c, true
}
}
return cmdNull, false
}
func getAuthorEmail(c *git.Commit) string {
sig := c.Author()
return sig.Email
}
func getCommitterEmail(c *git.Commit) string {
sig := c.Committer()
return sig.Email
}
// walkCommits traverses all the commits between two references,
// looking for scorsh commands, and tries to execute those if found
func walkCommits(msg spoolMsg, w *worker) error {
var cmdMsg *clientMsg
var cmdStack = make([]command, 0)
debug.log("[worker: %s] Inside walkCommits\n", w.Name)
reponame := msg.Repo
oldRev := msg.OldRev
newRev := msg.NewRev
repo, err := git.OpenRepository(reponame)
if err != nil {
fmt.Fprintf(os.Stderr, "Error while opening repository %s (%s)\n",
reponame, err)
return SCORSHerr(errNoRepo)
}
oldRevOid, _ := git.NewOid(oldRev)
oldrevCommit, err := repo.LookupCommit(oldRevOid)
if err != nil {
fmt.Fprintf(os.Stderr, "Commit: %s does not exist\n", oldRev)
return fmt.Errorf("%s: %s", SCORSHerr(errNoCommit), oldRev)
}
newRevOid, _ := git.NewOid(newRev)
newrevCommit, err := repo.LookupCommit(newRevOid)
if err != nil {
fmt.Fprintf(os.Stderr, "Commit: %s does not exist\n", newRev)
return fmt.Errorf("%s: %s", SCORSHerr(errNoCommit), newRev)
}
curCommit := newrevCommit
// FIXME: replace with a queue of commits
for curCommit.Id().String() != oldrevCommit.Id().String() {
commit, err := repo.LookupCommit(curCommit.Id())
if err == nil {
// We look for scorsh-commands, and if the commit has any, check
// if it can be verified by any of the keyrings associated with
// that specific scorsh-command
// Check if the commit contains a scorsh message
cmdMsg, err = findScorshMessage(commit)
if err == nil {
// the commit contains a valid scorsh message
// 1) get the list of all the keyrings which verify the message signature
validKeys := getValidKeys(commit, &(w.Keys))
debug.log("[worker: %s] validated keyrings on commit: %s\n", w.Name, validKeys)
// 2) then for each command in the message
for _, c := range cmdMsg.Commands {
if c.Cmd == "" {
// The command is empty -- ignore, log, and continue
log.Printf("[worker: %s] empty command\n", w.Name)
continue
}
// a) check that the command is among those accepted by the worker
debug.log("[worker: %s] validating command: %s\n", w.Name, c.Cmd)
var cmd = new(command)
var goodCmd, goodKeys bool
cmd.commandCfg, goodCmd = findCmdConfig(c.Cmd, w)
debug.log("[worker: %s] goodCmd: %s\n", w.Name, goodCmd)
if !goodCmd {
debug.log("[worker: %s] unsupported command: %s\n", w.Name, c.Cmd)
continue
}
// b) check that at least one of the accepted command keyrings
// is in valid_keys
goodKeys = intersectKeys(w.CommandKeys[c.Cmd], validKeys) != nil
debug.log("[worker: %s] goodKeys: %s\n", w.Name, goodKeys)
if !goodKeys {
debug.log("[worker: %s] no matching keys for command: %s\n", w.Name, c.Cmd)
continue
}
// c) If everything is OK, push the command to the stack
if goodCmd && goodKeys {
cmd.setEnvironment(&msg, curCommit.Id().String(), getAuthorEmail(commit), getCommitterEmail(commit))
cmd.Args = c.Args
cmdStack = append(cmdStack, *cmd)
}
}
} else {
log.Printf("[worker: %s] error parsing commit %s: %s", w.Name, curCommit.Id().String(), err)
}
// FIXME: ADD ALL THE PARENTS TO THE QUEUE OF COMMITS
curCommit = commit.Parent(0)
} else {
fmt.Printf("Commit %x not found!\n", curCommit.Id())
return SCORSHerr(errNoCommit)
}
}
// Now we can execute the commands in the stack, in the correct order...
stackHead := len(cmdStack) - 1
debug.log("[worker: %s] Executing command stack:\n", w.Name)
for i := range cmdStack {
//debug.log("[stack elem: %d] %s\n", i, cmdStack[stackHead-i].String())
// now we execute the command that emerges from the stack
cmd := cmdStack[stackHead-i]
errs := cmd.exec()
debug.log("[worker: %s] errors in command %s: %s\n", w.Name, cmd.Name, errs)
}
return nil
}