2 files changed, 34 insertions, 5 deletions
diff --git a/vendor/github.com/shazow/ssh-chat/internal/sanitize/sanitize.go b/vendor/github.com/shazow/ssh-chat/internal/sanitize/sanitize.go
new file mode 100644
index 00000000..ed532c97
--- /dev/null
+++ b/vendor/github.com/shazow/ssh-chat/internal/sanitize/sanitize.go
@@ -0,0 +1,28 @@
+package sanitize
+
+import "regexp"
+
+var reStripName = regexp.MustCompile("[^\\w.-]")
+
+const maxLength = 16
+
+// Name returns a name with only allowed characters and a reasonable length
+func Name(s string) string {
+	s = reStripName.ReplaceAllString(s, "")
+	nameLength := maxLength
+	if len(s) <= maxLength {
+		nameLength = len(s)
+	}
+	s = s[:nameLength]
+	return s
+}
+
+var reStripData = regexp.MustCompile("[^[:ascii:]]|[[:cntrl:]]")
+
+// Data returns a string with only allowed characters for client-provided metadata inputs.
+func Data(s string, maxlen int) string {
+	if len(s) > maxlen {
+		s = s[:maxlen]
+	}
+	return reStripData.ReplaceAllString(s, "")
+}
diff --git a/vendor/github.com/shazow/ssh-chat/sshd/auth.go b/vendor/github.com/shazow/ssh-chat/sshd/auth.go
index 2fc86fa8..afa7271a 100644
--- a/vendor/github.com/shazow/ssh-chat/sshd/auth.go
+++ b/vendor/github.com/shazow/ssh-chat/sshd/auth.go
@@ -6,6 +6,7 @@ import (
 	"errors"
 	"net"
 
+	"github.com/shazow/ssh-chat/internal/sanitize"
 	"golang.org/x/crypto/ssh"
 )
 
@@ -13,8 +14,8 @@ import (
 type Auth interface {
 	// Whether to allow connections without a public key.
 	AllowAnonymous() bool
-	// Given address and public key, return if the connection should be permitted.
-	Check(net.Addr, ssh.PublicKey) (bool, error)
+	// Given address and public key and client agent string, returns nil if the connection should be allowed.
+	Check(net.Addr, ssh.PublicKey, string) error
 }
 
 // MakeAuth makes an ssh.ServerConfig which performs authentication against an Auth implementation.
@@ -23,8 +24,8 @@ func MakeAuth(auth Auth) *ssh.ServerConfig {
 		NoClientAuth: false,
 		// Auth-related things should be constant-time to avoid timing attacks.
 		PublicKeyCallback: func(conn ssh.ConnMetadata, key ssh.PublicKey) (*ssh.Permissions, error) {
-			ok, err := auth.Check(conn.RemoteAddr(), key)
-			if !ok {
+			err := auth.Check(conn.RemoteAddr(), key, sanitize.Data(string(conn.ClientVersion()), 64))
+			if err != nil {
 				return nil, err
 			}
 			perm := &ssh.Permissions{Extensions: map[string]string{
@@ -36,7 +37,7 @@ func MakeAuth(auth Auth) *ssh.ServerConfig {
 			if !auth.AllowAnonymous() {
 				return nil, errors.New("public key authentication required")
 			}
-			_, err := auth.Check(conn.RemoteAddr(), nil)
+			err := auth.Check(conn.RemoteAddr(), nil, sanitize.Data(string(conn.ClientVersion()), 64))
 			return nil, err
 		},
 	}