github.com/tompreston/snapd@v0.0.0-20210817193607-954edfcb9611/cmd/snap/cmd_sign.go (about)

     1  // -*- Mode: Go; indent-tabs-mode: t -*-
     2  
     3  /*
     4   * Copyright (C) 2014-2021 Canonical Ltd
     5   *
     6   * This program is free software: you can redistribute it and/or modify
     7   * it under the terms of the GNU General Public License version 3 as
     8   * published by the Free Software Foundation.
     9   *
    10   * This program is distributed in the hope that it will be useful,
    11   * but WITHOUT ANY WARRANTY; without even the implied warranty of
    12   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    13   * GNU General Public License for more details.
    14   *
    15   * You should have received a copy of the GNU General Public License
    16   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
    17   *
    18   */
    19  
    20  package main
    21  
    22  import (
    23  	"fmt"
    24  	"io/ioutil"
    25  
    26  	"github.com/jessevdk/go-flags"
    27  
    28  	"github.com/snapcore/snapd/asserts/signtool"
    29  	"github.com/snapcore/snapd/i18n"
    30  )
    31  
    32  var shortSignHelp = i18n.G("Sign an assertion")
    33  var longSignHelp = i18n.G(`
    34  The sign command signs an assertion using the specified key, using the
    35  input for headers from a JSON mapping provided through stdin. The body
    36  of the assertion can be specified through a "body" pseudo-header.
    37  `)
    38  
    39  type cmdSign struct {
    40  	Positional struct {
    41  		Filename flags.Filename
    42  	} `positional-args:"yes"`
    43  
    44  	KeyName keyName `short:"k" default:"default"`
    45  }
    46  
    47  func init() {
    48  	cmd := addCommand("sign", shortSignHelp, longSignHelp, func() flags.Commander {
    49  		return &cmdSign{}
    50  	}, map[string]string{
    51  		// TRANSLATORS: This should not start with a lowercase letter.
    52  		"k": i18n.G("Name of the key to use, otherwise use the default key"),
    53  	}, []argDesc{{
    54  		// TRANSLATORS: This needs to begin with < and end with >
    55  		name: i18n.G("<filename>"),
    56  		// TRANSLATORS: This should not start with a lowercase letter.
    57  		desc: i18n.G("File to sign (defaults to stdin)"),
    58  	}})
    59  	cmd.hidden = true
    60  	cmd.completeHidden = true
    61  }
    62  
    63  func (x *cmdSign) Execute(args []string) error {
    64  	if len(args) > 0 {
    65  		return ErrExtraArgs
    66  	}
    67  
    68  	useStdin := x.Positional.Filename == "" || x.Positional.Filename == "-"
    69  
    70  	var (
    71  		statement []byte
    72  		err       error
    73  	)
    74  	if !useStdin {
    75  		statement, err = ioutil.ReadFile(string(x.Positional.Filename))
    76  	} else {
    77  		statement, err = ioutil.ReadAll(Stdin)
    78  	}
    79  	if err != nil {
    80  		return fmt.Errorf(i18n.G("cannot read assertion input: %v"), err)
    81  	}
    82  
    83  	keypairMgr, err := getKeypairManager()
    84  	if err != nil {
    85  		return err
    86  	}
    87  	privKey, err := keypairMgr.GetByName(string(x.KeyName))
    88  	if err != nil {
    89  		// TRANSLATORS: %q is the key name, %v the error message
    90  		return fmt.Errorf(i18n.G("cannot use %q key: %v"), x.KeyName, err)
    91  	}
    92  
    93  	signOpts := signtool.Options{
    94  		KeyID:     privKey.PublicKey().ID(),
    95  		Statement: statement,
    96  	}
    97  
    98  	encodedAssert, err := signtool.Sign(&signOpts, keypairMgr)
    99  	if err != nil {
   100  		return err
   101  	}
   102  
   103  	_, err = Stdout.Write(encodedAssert)
   104  	if err != nil {
   105  		return err
   106  	}
   107  	return nil
   108  }