podman ssh work, using new c/common interface

implement new ssh interface into podman

this completely redesigns the entire functionality of podman image scp,
podman system connection add, and podman --remote. All references to golang.org/x/crypto/ssh
have been moved to common as have native ssh/scp execs and the new usage of the sftp package.

this PR adds a global flag, --ssh to podman which has two valid inputs `golang` and `native` where golang is the default.
Users should not notice any difference in their everyday workflows if they continue using the golang option. UNLESS they have been using an improperly verified ssh key, this will now fail. This is because podman was incorrectly using the
ssh callback method to IGNORE the ssh known hosts file which is very insecure and golang tells you not yo use this in production.

The native paths allows for immense flexibility, with a new containers.conf field `SSH_CONFIG` that specifies a specific ssh config file to be used in all operations. Else the users ~/.ssh/config file will be used.
podman --remote currently only uses the golang path, given its deep interconnection with dialing multiple clients and urls.

My goal after this PR is to go back and abstract the idea of podman --remote from golang's dialed clients, as it should not be so intrinsically connected. Overall, this is a v1 of a long process of offering native ssh, and one that covers some good ground with podman system connection add and podman image scp.

Signed-off-by: Charlie Doern <cdoern@redhat.com>

3 files changed, 35 insertions, 5 deletions

diff --git a/vendor/golang.org/x/crypto/curve25519/curve25519.go b/vendor/golang.org/x/crypto/curve25519/curve25519.go
index cda3fdd35..bc62161d6 100644
--- a/vendor/golang.org/x/crypto/curve25519/curve25519.go
+++ b/vendor/golang.org/x/crypto/curve25519/curve25519.go
@@ -9,7 +9,8 @@ package curve25519 // import "golang.org/x/crypto/curve25519"
 
 import (
 	"crypto/subtle"
-	"fmt"
+	"errors"
+	"strconv"
 
 	"golang.org/x/crypto/curve25519/internal/field"
 )
@@ -124,10 +125,10 @@ func X25519(scalar, point []byte) ([]byte, error) {
 func x25519(dst *[32]byte, scalar, point []byte) ([]byte, error) {
 	var in [32]byte
 	if l := len(scalar); l != 32 {
-		return nil, fmt.Errorf("bad scalar length: %d, expected %d", l, 32)
+		return nil, errors.New("bad scalar length: " + strconv.Itoa(l) + ", expected 32")
 	}
 	if l := len(point); l != 32 {
-		return nil, fmt.Errorf("bad point length: %d, expected %d", l, 32)
+		return nil, errors.New("bad point length: " + strconv.Itoa(l) + ", expected 32")
 	}
 	copy(in[:], scalar)
 	if &point[0] == &Basepoint[0] {
@@ -138,7 +139,7 @@ func x25519(dst *[32]byte, scalar, point []byte) ([]byte, error) {
 		copy(base[:], point)
 		ScalarMult(dst, &in, &base)
 		if subtle.ConstantTimeCompare(dst[:], zero[:]) == 1 {
-			return nil, fmt.Errorf("bad input point: low order point")
+			return nil, errors.New("bad input point: low order point")
 		}
 	}
 	return dst[:], nil
diff --git a/vendor/golang.org/x/crypto/ssh/agent/client.go b/vendor/golang.org/x/crypto/ssh/agent/client.go
index dbc79d583..3c4d18a15 100644
--- a/vendor/golang.org/x/crypto/ssh/agent/client.go
+++ b/vendor/golang.org/x/crypto/ssh/agent/client.go
@@ -772,7 +772,7 @@ func (s *agentKeyringSigner) Sign(rand io.Reader, data []byte) (*ssh.Signature,
 }
 
 func (s *agentKeyringSigner) SignWithAlgorithm(rand io.Reader, data []byte, algorithm string) (*ssh.Signature, error) {
-	if algorithm == "" || algorithm == s.pub.Type() {
+	if algorithm == "" || algorithm == underlyingAlgo(s.pub.Type()) {
 		return s.Sign(rand, data)
 	}
 
@@ -791,6 +791,33 @@ func (s *agentKeyringSigner) SignWithAlgorithm(rand io.Reader, data []byte, algo
 
 var _ ssh.AlgorithmSigner = &agentKeyringSigner{}
 
+// certKeyAlgoNames is a mapping from known certificate algorithm names to the
+// corresponding public key signature algorithm.
+//
+// This map must be kept in sync with the one in certs.go.
+var certKeyAlgoNames = map[string]string{
+	ssh.CertAlgoRSAv01:        ssh.KeyAlgoRSA,
+	ssh.CertAlgoRSASHA256v01:  ssh.KeyAlgoRSASHA256,
+	ssh.CertAlgoRSASHA512v01:  ssh.KeyAlgoRSASHA512,
+	ssh.CertAlgoDSAv01:        ssh.KeyAlgoDSA,
+	ssh.CertAlgoECDSA256v01:   ssh.KeyAlgoECDSA256,
+	ssh.CertAlgoECDSA384v01:   ssh.KeyAlgoECDSA384,
+	ssh.CertAlgoECDSA521v01:   ssh.KeyAlgoECDSA521,
+	ssh.CertAlgoSKECDSA256v01: ssh.KeyAlgoSKECDSA256,
+	ssh.CertAlgoED25519v01:    ssh.KeyAlgoED25519,
+	ssh.CertAlgoSKED25519v01:  ssh.KeyAlgoSKED25519,
+}
+
+// underlyingAlgo returns the signature algorithm associated with algo (which is
+// an advertised or negotiated public key or host key algorithm). These are
+// usually the same, except for certificate algorithms.
+func underlyingAlgo(algo string) string {
+	if a, ok := certKeyAlgoNames[algo]; ok {
+		return a
+	}
+	return algo
+}
+
 // Calls an extension method. It is up to the agent implementation as to whether or not
 // any particular extension is supported and may always return an error. Because the
 // type of the response is up to the implementation, this returns the bytes of the
diff --git a/vendor/golang.org/x/crypto/ssh/certs.go b/vendor/golang.org/x/crypto/ssh/certs.go
index a69e22491..4600c2077 100644
--- a/vendor/golang.org/x/crypto/ssh/certs.go
+++ b/vendor/golang.org/x/crypto/ssh/certs.go
@@ -460,6 +460,8 @@ func (c *Certificate) SignCert(rand io.Reader, authority Signer) error {
 
 // certKeyAlgoNames is a mapping from known certificate algorithm names to the
 // corresponding public key signature algorithm.
+//
+// This map must be kept in sync with the one in agent/client.go.
 var certKeyAlgoNames = map[string]string{
 	CertAlgoRSAv01:        KeyAlgoRSA,
 	CertAlgoRSASHA256v01:  KeyAlgoRSASHA256,