scp: Check remote->local directory copy filenames

CVE-2019-6111

6 files changed, 233 insertions, 11 deletions

diff --git a/debian/.git-dpm b/debian/.git-dpm
index 992d37c60..8a18e26dc 100644
--- a/debian/.git-dpm
+++ b/debian/.git-dpm
@@ -1,6 +1,6 @@
 # see git-dpm(1) from git-dpm package
-2a8f710447442e9a03e71c022859112ec2d77d17
-2a8f710447442e9a03e71c022859112ec2d77d17
+125924e47db3713a85a70e0f8d6c23818d2ea054
+125924e47db3713a85a70e0f8d6c23818d2ea054
 3d246f10429fc9a37b98eabef94fe8dc7c61002b
 3d246f10429fc9a37b98eabef94fe8dc7c61002b
 openssh_7.9p1.orig.tar.gz
diff --git a/debian/changelog b/debian/changelog
index cc1cfd5f1..41b42221d 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -2,6 +2,9 @@ openssh (1:7.9p1-6) UNRELEASED; urgency=medium
 
   * CVE-2019-6109: Apply upstream patches to sanitize scp filenames via
     snmprintf (closes: #793412).
+  * CVE-2019-6111: Apply upstream patch to check in scp client that
+    filenames sent during remote->local directory copies satisfy the
+    wildcard specified by the user.
 
  -- Colin Watson <cjwatson@debian.org>  Fri, 08 Feb 2019 15:41:25 +0000
 
diff --git a/debian/patches/check-filenames-in-scp-client.patch b/debian/patches/check-filenames-in-scp-client.patch
new file mode 100644
index 000000000..519358ce6
--- /dev/null
+++ b/debian/patches/check-filenames-in-scp-client.patch
@@ -0,0 +1,187 @@
+From 125924e47db3713a85a70e0f8d6c23818d2ea054 Mon Sep 17 00:00:00 2001
+From: "djm@openbsd.org" <djm@openbsd.org>
+Date: Sat, 26 Jan 2019 22:41:28 +0000
+Subject: 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
+
+CVE-2019-6111
+
+Origin: backport, https://anongit.mindrot.org/openssh.git/commit/?id=391ffc4b9d31fa1f4ad566499fef9176ff8a07dc
+Last-Update: 2019-02-08
+
+Patch-Name: check-filenames-in-scp-client.patch
+---
+ scp.1 | 12 +++++++++++-
+ scp.c | 37 +++++++++++++++++++++++++++++--------
+ 2 files changed, 40 insertions(+), 9 deletions(-)
+
+diff --git a/scp.1 b/scp.1
+index 0e5cc1b2d..397e77091 100644
+--- a/scp.1
++++ b/scp.1
+@@ -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
+@@ -208,6 +208,16 @@ 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 1971c80cd..035037bcc 100644
+--- a/scp.c
++++ b/scp.c
+@@ -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>
+@@ -383,14 +384,14 @@ 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 *[]);
+@@ -429,8 +430,9 @@ 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:")) != -1)
++       fflag = Tflag = tflag = 0;
++       while ((ch = getopt(argc, argv,
++           "dfl:prtTvBCc:i:P:q12346S:o:F:")) != -1) {
+                switch (ch) {
+                /* User-visible flags. */
+                case '1':
+@@ -509,9 +511,13 @@ main(int argc, char **argv)
+                        setmode(0, O_BINARY);
+ #endif
+                        break;
++               case 'T':
++                       Tflag = 1;
++                       break;
+                default:
+                        usage();
+                }
++       }
+        argc -= optind;
+        argv += optind;
+ 
+@@ -542,7 +548,7 @@ main(int argc, char **argv)
+        }
+        if (tflag) {
+                /* Receive data. */
+-               sink(argc, argv);
++               sink(argc, argv, NULL);
+                exit(errs != 0);
+        }
+        if (argc < 2)
+@@ -800,7 +806,7 @@ 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;
+        }
+@@ -976,7 +982,7 @@ 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;
+@@ -992,6 +998,7 @@ 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]
+@@ -1016,6 +1023,17 @@ 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)
+@@ -1120,6 +1138,9 @@ 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;
+@@ -1157,7 +1178,7 @@ 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)
diff --git a/debian/patches/series b/debian/patches/series
index 710e56b7b..4403cba3b 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -27,3 +27,4 @@ conch-old-privkey-format.patch
 scp-disallow-dot-or-empty-filename.patch
 sanitize-scp-filenames-via-snmprintf.patch
 have-progressmeter-force-update-at-beginning-and-end-transfer.patch
+check-filenames-in-scp-client.patch
diff --git a/scp.1 b/scp.1
index 0e5cc1b2d..397e77091 100644
--- a/scp.1
+++ b/scp.1
@@ -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
@@ -208,6 +208,16 @@ 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 1971c80cd..035037bcc 100644
--- a/scp.c
+++ b/scp.c
@@ -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>
@@ -383,14 +384,14 @@ 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 *[]);
@@ -429,8 +430,9 @@ 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:")) != -1)
+        fflag = Tflag = tflag = 0;
+        while ((ch = getopt(argc, argv,
+            "dfl:prtTvBCc:i:P:q12346S:o:F:")) != -1) {
                 switch (ch) {
                 /* User-visible flags. */
                 case '1':
@@ -509,9 +511,13 @@ main(int argc, char **argv)
                         setmode(0, O_BINARY);
 #endif
                         break;
+                case 'T':
+                        Tflag = 1;
+                        break;
                 default:
                         usage();
                 }
+        }
         argc -= optind;
         argv += optind;
 
@@ -542,7 +548,7 @@ main(int argc, char **argv)
         }
         if (tflag) {
                 /* Receive data. */
-                sink(argc, argv);
+                sink(argc, argv, NULL);
                 exit(errs != 0);
         }
         if (argc < 2)
@@ -800,7 +806,7 @@ 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;
         }
@@ -976,7 +982,7 @@ 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;
@@ -992,6 +998,7 @@ 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]
@@ -1016,6 +1023,17 @@ 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)
@@ -1120,6 +1138,9 @@ 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;
@@ -1157,7 +1178,7 @@ 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)