From e83897f1bff97275e02e9e452d8d5282131128f6 Mon Sep 17 00:00:00 2001 From: "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 Origin: upstream, https://anongit.mindrot.org/openssh.git/commit/?id=391ffc4b9d31fa1f4ad566499fef9176ff8a07dc Last-Update: 2019-02-08 Patch-Name: check-filenames-in-scp-client.patch Ported to Stretch (OpenSSH 7.4) by Yves-Alexis Perez CVE-2019-6111 --- scp.1 | 17 +++++++++++++---- scp.c | 35 +++++++++++++++++++++++++++-------- 2 files changed, 40 insertions(+), 12 deletions(-) diff --git a/scp.1 b/scp.1 index 4ae87775..695a9cb2 100644 --- a/scp.1 +++ b/scp.1 @@ -8,9 +8,9 @@ .\" .\" Created: Sun May 7 00:14:37 1995 ylo .\" -.\" $OpenBSD: scp.1,v 1.71 2016/07/16 06:57:55 jmc Exp $ +.\" $OpenBSD: scp.1,v 1.85 2019/01/26 22:41:28 djm Exp $ .\" -.Dd $Mdocdate: July 16 2016 $ +.Dd $Mdocdate: January 26 2019 $ .Dt SCP 1 .Os .Sh NAME @@ -18,8 +18,7 @@ .Nd secure copy (remote file copy program) .Sh SYNOPSIS .Nm scp -.Bk -words -.Op Fl 12346BCpqrv +.Op Fl 12346BCpqrTv .Op Fl c Ar cipher .Op Fl F Ar ssh_config .Op Fl i Ar identity_file @@ -215,6 +214,16 @@ 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 2f5a4d46..44b74fa4 100644 --- a/scp.c +++ b/scp.c @@ -94,6 +94,7 @@ #include #include #include +#include #include #include #include @@ -362,14 +363,14 @@ 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(char *, int, char *[]); @@ -406,8 +407,8 @@ main(int argc, char **argv) addargs(&args, "-oPermitLocalCommand=no"); addargs(&args, "-oClearAllForwardings=yes"); - 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': @@ -483,6 +484,9 @@ main(int argc, char **argv) setmode(0, O_BINARY); #endif break; + case 'T': + Tflag = 1; + break; default: usage(); } @@ -516,7 +520,7 @@ main(int argc, char **argv) } if (tflag) { /* Receive data. */ - sink(argc, argv); + sink(argc, argv, NULL); exit(errs != 0); } if (argc < 2) @@ -757,7 +761,7 @@ 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; } @@ -925,7 +929,7 @@ rsource(char *name, struct stat *statp) } void -sink(int argc, char **argv) +sink(int argc, char **argv, const char *src) { static BUF buffer; struct stat stb; @@ -941,6 +945,7 @@ 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] @@ -962,6 +967,17 @@ 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) @@ -1061,6 +1077,9 @@ 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; @@ -1098,7 +1117,7 @@ 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)