From 125924e47db3713a85a70e0f8d6c23818d2ea054 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 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 #include #include +#include #include #include #include @@ -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)