- djm@cvs.openbsd.org 2006/01/31 10:19:02

     [misc.c misc.h scp.c sftp.c]
     fix local arbitrary command execution vulnerability on local/local and
     remote/remote copies (CVE-2006-0225, bz #1094), patch by
     t8m AT centrum.cz, polished by dtucker@ and myself; ok markus@

1 files changed, 87 insertions, 45 deletions

diff --git a/scp.c b/scp.c
index 5dced6ce4..2467dcb5c 100644
--- a/scp.c
+++ b/scp.c
@@ -71,7 +71,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: scp.c,v 1.128 2005/12/06 22:38:27 reyk Exp $");
+RCSID("$OpenBSD: scp.c,v 1.129 2006/01/31 10:19:02 djm Exp $");
 
 #include "xmalloc.h"
 #include "atomicio.h"
@@ -118,6 +118,48 @@ killchild(int signo)
         exit(1);
 }
 
+static int
+do_local_cmd(arglist *a)
+{
+        u_int i;
+        int status;
+        pid_t pid;
+
+        if (a->num == 0)
+                fatal("do_local_cmd: no arguments");
+
+        if (verbose_mode) {
+                fprintf(stderr, "Executing:");
+                for (i = 0; i < a->num; i++)
+                        fprintf(stderr, " %s", a->list[i]);
+                fprintf(stderr, "\n");
+        }
+        if ((pid = fork()) == -1)
+                fatal("do_local_cmd: fork: %s", strerror(errno));
+
+        if (pid == 0) {
+                execvp(a->list[0], a->list);
+                perror(a->list[0]);
+                exit(1);
+        }
+
+        do_cmd_pid = pid;
+        signal(SIGTERM, killchild);
+        signal(SIGINT, killchild);
+        signal(SIGHUP, killchild);
+
+        while (waitpid(pid, &status, 0) == -1)
+                if (errno != EINTR)
+                        fatal("do_local_cmd: waitpid: %s", strerror(errno));
+
+        do_cmd_pid = -1;
+
+        if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
+                return (-1);
+
+        return (0);
+}
+
 /*
  * This function executes the given command as the specified user on the
  * given host.  This returns < 0 if execution fails, and >= 0 otherwise. This
@@ -162,7 +204,7 @@ do_cmd(char *host, char *remuser, char *cmd, int *fdin, int *fdout, int argc)
                 close(pin[0]);
                 close(pout[1]);
 
-                args.list[0] = ssh_program;
+                replacearg(&args, 0, "%s", ssh_program);
                 if (remuser != NULL)
                         addargs(&args, "-l%s", remuser);
                 addargs(&args, "%s", host);
@@ -227,8 +269,9 @@ main(int argc, char **argv)
 
         __progname = ssh_get_progname(argv[0]);
 
+        memset(&args, '\0', sizeof(args));
         args.list = NULL;
-        addargs(&args, "ssh");          /* overwritten with ssh_program */
+        addargs(&args, "%s", ssh_program);
         addargs(&args, "-x");
         addargs(&args, "-oForwardAgent no");
         addargs(&args, "-oPermitLocalCommand no");
@@ -368,6 +411,10 @@ toremote(char *targ, int argc, char **argv)
 {
         int i, len;
         char *bp, *host, *src, *suser, *thost, *tuser, *arg;
+        arglist alist;
+
+        memset(&alist, '\0', sizeof(alist));
+        alist.list = NULL;
 
         *targ++ = 0;
         if (*targ == 0)
@@ -385,56 +432,48 @@ toremote(char *targ, int argc, char **argv)
                 tuser = NULL;
         }
 
+        if (tuser != NULL && !okname(tuser)) {
+                xfree(arg);
+                return;
+        }
+
         for (i = 0; i < argc - 1; i++) {
                 src = colon(argv[i]);
                 if (src) {      /* remote to remote */
-                        static char *ssh_options =
-                            "-x -o'ClearAllForwardings yes'";
+                        freeargs(&alist);
+                        addargs(&alist, "%s", ssh_program);
+                        if (verbose_mode)
+                                addargs(&alist, "-v");
+                        addargs(&alist, "-x");
+                        addargs(&alist, "-oClearAllForwardings yes");
+                        addargs(&alist, "-n");
+
                         *src++ = 0;
                         if (*src == 0)
                                 src = ".";
                         host = strrchr(argv[i], '@');
-                        len = strlen(ssh_program) + strlen(argv[i]) +
-                            strlen(src) + (tuser ? strlen(tuser) : 0) +
-                            strlen(thost) + strlen(targ) +
-                            strlen(ssh_options) + CMDNEEDS + 20;
-                        bp = xmalloc(len);
+
                         if (host) {
                                 *host++ = 0;
                                 host = cleanhostname(host);
                                 suser = argv[i];
                                 if (*suser == '\0')
                                         suser = pwd->pw_name;
-                                else if (!okname(suser)) {
-                                        xfree(bp);
+                                else if (!okname(suser))
                                         continue;
-                                }
-                                if (tuser && !okname(tuser)) {
-                                        xfree(bp);
-                                        continue;
-                                }
-                                snprintf(bp, len,
-                                    "%s%s %s -n "
-                                    "-l %s %s %s %s '%s%s%s:%s'",
-                                    ssh_program, verbose_mode ? " -v" : "",
-                                    ssh_options, suser, host, cmd, src,
-                                    tuser ? tuser : "", tuser ? "@" : "",
-                                    thost, targ);
+                                addargs(&alist, "-l");
+                                addargs(&alist, "%s", suser);
                         } else {
                                 host = cleanhostname(argv[i]);
-                                snprintf(bp, len,
-                                    "exec %s%s %s -n %s "
-                                    "%s %s '%s%s%s:%s'",
-                                    ssh_program, verbose_mode ? " -v" : "",
-                                    ssh_options, host, cmd, src,
-                                    tuser ? tuser : "", tuser ? "@" : "",
-                                    thost, targ);
                         }
-                        if (verbose_mode)
-                                fprintf(stderr, "Executing: %s\n", bp);
-                        if (system(bp) != 0)
+                        addargs(&alist, "%s", host);
+                        addargs(&alist, "%s", cmd);
+                        addargs(&alist, "%s", src);
+                        addargs(&alist, "%s%s%s:%s",
+                            tuser ? tuser : "", tuser ? "@" : "",
+                            thost, targ);
+                        if (do_local_cmd(&alist) != 0)
                                 errs = 1;
-                        (void) xfree(bp);
                 } else {        /* local to remote */
                         if (remin == -1) {
                                 len = strlen(targ) + CMDNEEDS + 20;
@@ -458,20 +497,23 @@ tolocal(int argc, char **argv)
 {
         int i, len;
         char *bp, *host, *src, *suser;
+        arglist alist;
+
+        memset(&alist, '\0', sizeof(alist));
+        alist.list = NULL;
 
         for (i = 0; i < argc - 1; i++) {
                 if (!(src = colon(argv[i]))) {  /* Local to local. */
-                        len = strlen(_PATH_CP) + strlen(argv[i]) +
-                            strlen(argv[argc - 1]) + 20;
-                        bp = xmalloc(len);
-                        (void) snprintf(bp, len, "exec %s%s%s %s %s", _PATH_CP,
-                            iamrecursive ? " -r" : "", pflag ? " -p" : "",
-                            argv[i], argv[argc - 1]);
-                        if (verbose_mode)
-                                fprintf(stderr, "Executing: %s\n", bp);
-                        if (system(bp))
+                        freeargs(&alist);
+                        addargs(&alist, "%s", _PATH_CP);
+                        if (iamrecursive)
+                                addargs(&alist, "-r");
+                        if (pflag)
+                                addargs(&alist, "-p");
+                        addargs(&alist, "%s", argv[i]);
+                        addargs(&alist, "%s", argv[argc-1]);
+                        if (do_local_cmd(&alist))
                                 ++errs;
-                        (void) xfree(bp);
                         continue;
                 }
                 *src++ = 0;