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// -*- Mode: Go; indent-tabs-mode: t -*-
//go:build !nosecboot
/*
* Copyright (C) 2025 Canonical Ltd
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
package secboot
import (
"fmt"
"os"
"os/exec"
"time"
sb "github.com/snapcore/secboot"
"github.com/snapcore/snapd/logger"
)
var (
osExit = os.Exit
osReadlink = os.Readlink
sbWaitForAndRunArgon2OutOfProcessRequest = sb.WaitForAndRunArgon2OutOfProcessRequest
sbNewOutOfProcessArgon2KDF = sb.NewOutOfProcessArgon2KDF
sbSetArgon2KDF = sb.SetArgon2KDF
)
const (
outOfProcessArgon2KDFTimeout = 100 * time.Millisecond
)
// HijackAndRunArgon2OutOfProcessHandlerOnArg is supposed to be called from the
// main() of binaries involved with sealing/unsealing of keys (i.e. snapd and
// snap-bootstrap).
//
// This switches the binary to a special argon2 mode when the matching args are
// detected where it hijacks the process and acts as an argon2 out-of-process
// helper command and exits when its work is done, otherwise (in normal mode)
// it sets the default argon2 kdf implementation to be self-invoking into the
// special argon2 mode of the calling binary.
//
// For more context, check docs for sb.WaitForAndRunArgon2OutOfProcessRequest
// and sb.NewOutOfProcessArgon2KDF for details on how the flow works
// in secboot.
func HijackAndRunArgon2OutOfProcessHandlerOnArg(args []string) {
if !isOutOfProcessArgon2KDFMode(args) {
// Binary was invoked in normal mode, let's setup default argon2 kdf implementation
// to point to this binary when invoked using special args.
exe, err := osReadlink("/proc/self/exe")
if err != nil {
logger.Noticef("internal error: failed to read symlink of /proc/self/exe: %v", err)
return
}
handlerCmd := func() (*exec.Cmd, error) {
cmd := exec.Command(exe, args...)
return cmd, nil
}
argon2KDF := sbNewOutOfProcessArgon2KDF(handlerCmd, outOfProcessArgon2KDFTimeout, nil)
sbSetArgon2KDF(argon2KDF)
return
}
logger.Noticef("running argon2 out-of-process helper")
// Ignore the lock release callback and use implicit release on process termination.
_, err := sbWaitForAndRunArgon2OutOfProcessRequest(os.Stdin, os.Stdout, sb.NoArgon2OutOfProcessWatchdogHandler())
if err != nil {
fmt.Fprintf(os.Stderr, "cannot run argon2 out-of-process request: %v", err)
osExit(1)
}
// Argon2 request was processed successfully
osExit(0)
panic("internal error: not reachable")
}
|
