From 48a17cff6aa104b8e806ddb2191f83f1024060f1 Mon Sep 17 00:00:00 2001
From: Matt Johnston <matt@ucc.asn.au>
Date: Tue, 9 Dec 2025 22:59:19 +0900
Subject: [PATCH] scp CVE-2019-6111 fix

Cherry-pick from OpenSSH portable

391ffc4b9d31 ("upstream: check in scp client that filenames sent during")

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@

CVE: CVE-2019-6111
Upstream-Status: Backport [https://github.com/mkj/dropbear/commit/48a17cff6aa104b8e806ddb2191f83f1024060f1]
Signed-off-by: Peter Marko <peter.marko@siemens.com>
---
 src/scp.c | 38 +++++++++++++++++++++++++++++---------
 1 file changed, 29 insertions(+), 9 deletions(-)

diff --git a/src/scp.c b/src/scp.c
index 384f2cb..bf98986 100644
--- a/src/scp.c
+++ b/src/scp.c
@@ -76,6 +76,8 @@
 #include "includes.h"
 /*RCSID("$OpenBSD: scp.c,v 1.130 2006/01/31 10:35:43 djm Exp $");*/
 
+#include <fnmatch.h>
+
 #include "atomicio.h"
 #include "compat.h"
 #include "scpmisc.h"
@@ -291,14 +293,14 @@ void verifydir(char *);
 
 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(char *, int, char *[]);
@@ -325,8 +327,8 @@ main(int argc, char **argv)
 	args.list = NULL;
 	addargs(&args, "%s", ssh_program);
 
-	fflag = tflag = 0;
-	while ((ch = getopt(argc, argv, "dfl:prtvBCc:i:P:q1246S:o:F:")) != -1)
+	fflag = Tflag = tflag = 0;
+	while ((ch = getopt(argc, argv, "dfl:prtTvBCc:i:P:q1246S:o:F:")) != -1)
 		switch (ch) {
 		/* User-visible flags. */
 		case '1':
@@ -389,9 +391,12 @@ main(int argc, char **argv)
 			setmode(0, O_BINARY);
 #endif
 			break;
+		case 'T':
+			Tflag = 1;
+			break;
 		default:
 			usage();
-		}
+	}
 	argc -= optind;
 	argv += optind;
 
@@ -409,7 +414,7 @@ main(int argc, char **argv)
 	}
 	if (tflag) {
 		/* Receive data. */
-		sink(argc, argv);
+		sink(argc, argv, NULL);
 		exit(errs != 0);
 	}
 	if (argc < 2)
@@ -589,7 +594,7 @@ tolocal(int argc, char **argv)
 			continue;
 		}
 		xfree(bp);
-		sink(1, argv + argc - 1);
+		sink(1, argv + argc - 1, src);
 		(void) close(remin);
 		remin = remout = -1;
 	}
@@ -822,7 +827,7 @@ bwlimit(int amount)
 }
 
 void
-sink(int argc, char **argv)
+sink(int argc, char **argv, const char *src)
 {
 	static BUF buffer;
 	struct stat stb;
@@ -836,6 +841,7 @@ sink(int argc, char **argv)
 	off_t size, statbytes;
 	int setimes, targisdir, wrerrno = 0;
 	char ch, *cp, *np, *targ, *why, *vect[1], buf[2048];
+	char *src_copy = NULL, *restrict_pattern = NULL;
 	struct timeval tv[2];
 
 #define	atime	tv[0]
@@ -857,6 +863,17 @@ 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)
@@ -939,6 +956,9 @@ 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 = NULL;
 			static size_t cursize = 0;
@@ -977,7 +997,7 @@ 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)
