scp: do not spawn ssh with two -s flags for remote-to-remote copies

Do not add another "-s" to the argument vector every time an SFTP
connection is initiated.  Instead, introduce a subsystem flag to
do_cmd() and add "-s" when the flag is set.

ok djm@

diff --git a/usr.bin/ssh/scp.c b/usr.bin/ssh/scp.c
index ce133d8..f31dd71 100644 (file)
--- a/usr.bin/ssh/scp.c
+++ b/usr.bin/ssh/scp.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: scp.c,v 1.230 2021/08/10 03:33:34 djm Exp $ */
+/* $OpenBSD: scp.c,v 1.231 2021/08/11 14:05:19 naddy Exp $ */
 /*
  * scp - secure remote copy.  This is basically patched BSD rcp which
  * uses ssh to do the data transfer (instead of using rcmd).
@@ -112,10 +112,8 @@
 
 #define COPY_BUFLEN    16384
 
-int do_cmd(char *program, char *host, char *remuser, int port, char *cmd,
-    int *fdin, int *fdout, pid_t *pidp);
-int do_cmd2(char *host, char *remuser, int port, char *cmd,
-    int fdin, int fdout);
+int do_cmd(char *, char *, char *, int, int, char *, int *, int *, pid_t *);
+int do_cmd2(char *, char *, int, char *, int, int);
 
 /* Struct for addargs */
 arglist args;
@@ -244,8 +242,8 @@ do_local_cmd(arglist *a)
  */
 
 int
-do_cmd(char *program, char *host, char *remuser, int port, char *cmd,
-    int *fdin, int *fdout, pid_t *pid)
+do_cmd(char *program, char *host, char *remuser, int port, int subsystem,
+    char *cmd, int *fdin, int *fdout, pid_t *pid)
 {
        int pin[2], pout[2], reserved[2];
 
@@ -299,6 +297,8 @@ do_cmd(char *program, char *host, char *remuser, int port, char *cmd,
                        addargs(&args, "-l");
                        addargs(&args, "%s", remuser);
                }
+               if (subsystem)
+                       addargs(&args, "-s");
                addargs(&args, "--");
                addargs(&args, "%s", host);
                addargs(&args, "%s", cmd);
@@ -929,15 +929,14 @@ do_sftp_connect(char *host, char *user, int port, char *sftp_direct,
    int *reminp, int *remoutp, int *pidp)
 {
        if (sftp_direct == NULL) {
-               addargs(&args, "-s");
-               if (do_cmd(ssh_program, host, user, port, "sftp",
+               if (do_cmd(ssh_program, host, user, port, 1, "sftp",
                    reminp, remoutp, pidp) < 0)
                        return NULL;
 
        } else {
                args.list = NULL;
                addargs(&args, "sftp-server");
-               if (do_cmd(sftp_direct, host, NULL, -1, "sftp",
+               if (do_cmd(sftp_direct, host, NULL, -1, 0, "sftp",
                    reminp, remoutp, pidp) < 0)
                        return NULL;
        }
@@ -1036,7 +1035,7 @@ toremote(int argc, char **argv, enum scp_mode_e mode, char *sftp_direct)
                        } else {
                                xasprintf(&bp, "%s -f %s%s", cmd,
                                    *src == '-' ? "-- " : "", src);
-                               if (do_cmd(ssh_program, host, suser, sport,
+                               if (do_cmd(ssh_program, host, suser, sport, 0,
                                    bp, &remin, &remout, &do_cmd_pid) < 0)
                                        exit(1);
                                free(bp);
@@ -1114,8 +1113,8 @@ toremote(int argc, char **argv, enum scp_mode_e mode, char *sftp_direct)
                        if (remin == -1) {
                                xasprintf(&bp, "%s -t %s%s", cmd,
                                    *targ == '-' ? "-- " : "", targ);
-                               if (do_cmd(ssh_program, thost, tuser, tport, bp,
-                                   &remin, &remout, &do_cmd_pid) < 0)
+                               if (do_cmd(ssh_program, thost, tuser, tport, 0,
+                                   bp, &remin, &remout, &do_cmd_pid) < 0)
                                        exit(1);
                                if (response() < 0)
                                        exit(1);
@@ -1199,7 +1198,7 @@ tolocal(int argc, char **argv, enum scp_mode_e mode, char *sftp_direct)
                /* SCP */
                xasprintf(&bp, "%s -f %s%s",
                    cmd, *src == '-' ? "-- " : "", src);
-               if (do_cmd(ssh_program, host, suser, sport, bp,
+               if (do_cmd(ssh_program, host, suser, sport, 0, bp,
                    &remin, &remout, &do_cmd_pid) < 0) {
                        free(bp);
                        ++errs;