upstream: check in scp client that filenames sent during

remote->local directory copies satisfy the wildcard specified by the user.

This checking provides some protection against a malicious server
sending unexpected filenames, but it comes at a risk of rejecting wanted
files due to differences between client and server wildcard expansion rules.

For this reason, this also adds a new -T flag to disable the check.

reported by Harry Sintonen
fix approach suggested by markus@;
has been in snaps for ~1wk courtesy deraadt@

OpenBSD-Commit-ID: 00f44b50d2be8e321973f3c6d014260f8f7a8eda

diff --git a/scp.1 b/scp.1
index 8bb63edaafc2439b09f558bcaa8ce620467f04cc..a2833dab041fa5a1757d13cba17abab20e0f2493 100644 (file)
--- a/scp.1
+++ b/scp.1
@@ -8,9 +8,9 @@
 .\"
 .\" Created: Sun May  7 00:14:37 1995 ylo
 .\"
-.\" $OpenBSD: scp.1,v 1.84 2019/01/22 06:58:31 jmc Exp $
+.\" $OpenBSD: scp.1,v 1.85 2019/01/26 22:41:28 djm Exp $
 .\"
-.Dd $Mdocdate: January 22 2019 $
+.Dd $Mdocdate: January 26 2019 $
 .Dt SCP 1
 .Os
 .Sh NAME
@@ -18,7 +18,7 @@
 .Nd secure copy (remote file copy program)
 .Sh SYNOPSIS
 .Nm scp
-.Op Fl 346BCpqrv
+.Op Fl 346BCpqrTv
 .Op Fl c Ar cipher
 .Op Fl F Ar ssh_config
 .Op Fl i Ar identity_file
@@ -222,6 +222,16 @@ to use for the encrypted connection.
 The program must understand
 .Xr ssh 1
 options.
+.It Fl T
+Disable strict filename checking.
+By default when copying files from a remote host to a local directory
+.Nm
+checks that the received filenames match those requested on the command-line
+to prevent the remote end from sending unexpected or unwanted files.
+Because of differences in how various operating systems and shells interpret
+filename wildcards, these checks may cause wanted files to be rejected.
+This option disables these checks at the expense of fully trusting that
+the server will not send unexpected filenames.
 .It Fl v
 Verbose mode.
 Causes

diff --git a/scp.c b/scp.c
index 74dfe521aad1d655977af94fa96dc14ff18eb1fd..e669e815effaffbf49c0a872a724b898ce1657da 100644 (file)
--- a/scp.c
+++ b/scp.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: scp.c,v 1.201 2019/01/24 16:52:17 dtucker Exp $ */
+/* $OpenBSD: scp.c,v 1.202 2019/01/26 22:41:28 djm Exp $ */
 /*
  * scp - secure remote copy.  This is basically patched BSD rcp which
  * uses ssh to do the data transfer (instead of using rcmd).
@@ -94,6 +94,7 @@
 #include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <fnmatch.h>
 #include <limits.h>
 #include <locale.h>
 #include <pwd.h>
@@ -375,14 +376,14 @@ void verifydir(char *);
 struct passwd *pwd;
 uid_t userid;
 int errs, remin, remout;
-int pflag, iamremote, iamrecursive, targetshouldbedirectory;
+int Tflag, pflag, iamremote, iamrecursive, targetshouldbedirectory;
 
 #define        CMDNEEDS        64
 char cmd[CMDNEEDS];            /* must hold "rcp -r -p -d\0" */
 
 int response(void);
 void rsource(char *, struct stat *);
-void sink(int, char *[]);
+void sink(int, char *[], const char *);
 void source(int, char *[]);
 void tolocal(int, char *[]);
 void toremote(int, char *[]);
@@ -423,8 +424,9 @@ main(int argc, char **argv)
        addargs(&args, "-oRemoteCommand=none");
        addargs(&args, "-oRequestTTY=no");
 
-       fflag = tflag = 0;
-       while ((ch = getopt(argc, argv, "dfl:prtvBCc:i:P:q12346S:o:F:J:")) != -1)
+       fflag = Tflag = tflag = 0;
+       while ((ch = getopt(argc, argv,
+           "dfl:prtTvBCc:i:P:q12346S:o:F:J:")) != -1) {
                switch (ch) {
                /* User-visible flags. */
                case '1':
@@ -504,9 +506,13 @@ main(int argc, char **argv)
                        setmode(0, O_BINARY);
 #endif
                        break;
+               case 'T':
+                       Tflag = 1;
+                       break;
                default:
                        usage();
                }
+       }
        argc -= optind;
        argv += optind;
 
@@ -537,7 +543,7 @@ main(int argc, char **argv)
        }
        if (tflag) {
                /* Receive data. */
-               sink(argc, argv);
+               sink(argc, argv, NULL);
                exit(errs != 0);
        }
        if (argc < 2)
@@ -795,7 +801,7 @@ tolocal(int argc, char **argv)
                        continue;
                }
                free(bp);
-               sink(1, argv + argc - 1);
+               sink(1, argv + argc - 1, src);
                (void) close(remin);
                remin = remout = -1;
        }
@@ -971,7 +977,7 @@ rsource(char *name, struct stat *statp)
         (sizeof(type) != 4 && sizeof(type) != 8))
 
 void
-sink(int argc, char **argv)
+sink(int argc, char **argv, const char *src)
 {
        static BUF buffer;
        struct stat stb;
@@ -987,6 +993,7 @@ sink(int argc, char **argv)
        unsigned long long ull;
        int setimes, targisdir, wrerrno = 0;
        char ch, *cp, *np, *targ, *why, *vect[1], buf[2048], visbuf[2048];
+       char *src_copy = NULL, *restrict_pattern = NULL;
        struct timeval tv[2];
 
 #define        atime   tv[0]
@@ -1011,6 +1018,17 @@ sink(int argc, char **argv)
        (void) atomicio(vwrite, remout, "", 1);
        if (stat(targ, &stb) == 0 && S_ISDIR(stb.st_mode))
                targisdir = 1;
+       if (src != NULL && !iamrecursive && !Tflag) {
+               /*
+                * Prepare to try to restrict incoming filenames to match
+                * the requested destination file glob.
+                */
+               if ((src_copy = strdup(src)) == NULL)
+                       fatal("strdup failed");
+               if ((restrict_pattern = strrchr(src_copy, '/')) != NULL) {
+                       *restrict_pattern++ = '\0';
+               }
+       }
        for (first = 1;; first = 0) {
                cp = buf;
                if (atomicio(read, remin, cp, 1) != 1)
@@ -1115,6 +1133,9 @@ sink(int argc, char **argv)
                        run_err("error: unexpected filename: %s", cp);
                        exit(1);
                }
+               if (restrict_pattern != NULL &&
+                   fnmatch(restrict_pattern, cp, 0) != 0)
+                       SCREWUP("filename does not match request");
                if (targisdir) {
                        static char *namebuf;
                        static size_t cursize;
@@ -1152,7 +1173,7 @@ sink(int argc, char **argv)
                                        goto bad;
                        }
                        vect[0] = xstrdup(np);
-                       sink(1, vect);
+                       sink(1, vect, src);
                        if (setimes) {
                                setimes = 0;
                                if (utimes(vect[0], tv) < 0)