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upstream: when receving a file in sink(), be careful to send at
most a single error response after the file has been opened. Otherwise the
source() and sink() can become desyncronised. Reported by Daniel Goujot,
Georges-Axel Jaloyan, Ryan Lahfa, and David Naccache.

ok deraadt@ markus@

OpenBSD-Commit-ID: 6c14d233c97349cb811a8f7921ded3ae7d9e0035
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djmdjm committed May 1, 2020
1 parent 3190969 commit aad87b8
Showing 1 changed file with 59 additions and 37 deletions.
96 changes: 59 additions & 37 deletions scp.c
@@ -1,4 +1,4 @@
/* $OpenBSD: scp.c,v 1.208 2020/04/30 17:07:10 markus Exp $ */
/* $OpenBSD: scp.c,v 1.209 2020/05/01 06:31:42 djm Exp $ */
/*
* scp - secure remote copy. This is basically patched BSD rcp which
* uses ssh to do the data transfer (instead of using rcmd).
Expand Down Expand Up @@ -374,6 +374,7 @@ BUF *allocbuf(BUF *, int, int);
void lostconn(int);
int okname(char *);
void run_err(const char *,...);
int note_err(const char *,...);
void verifydir(char *);

struct passwd *pwd;
Expand Down Expand Up @@ -1231,17 +1232,14 @@ sink(int argc, char **argv, const char *src)
{
static BUF buffer;
struct stat stb;
enum {
YES, NO, DISPLAYED
} wrerr;
BUF *bp;
off_t i;
size_t j, count;
int amt, exists, first, ofd;
mode_t mode, omode, mask;
off_t size, statbytes;
unsigned long long ull;
int setimes, targisdir, wrerrno = 0;
int setimes, targisdir, wrerr;
char ch, *cp, *np, *targ, *why, *vect[1], buf[2048], visbuf[2048];
char **patterns = NULL;
size_t n, npatterns = 0;
Expand Down Expand Up @@ -1450,8 +1448,13 @@ bad: run_err("%s: %s", np, strerror(errno));
continue;
}
cp = bp->buf;
wrerr = NO;
wrerr = 0;

/*
* NB. do not use run_err() unless immediately followed by
* exit() below as it may send a spurious reply that might
* desyncronise us from the peer. Use note_err() instead.
*/
statbytes = 0;
if (showprogress)
start_progress_meter(curfile, size, &statbytes);
Expand All @@ -1476,38 +1479,36 @@ bad: run_err("%s: %s", np, strerror(errno));

if (count == bp->cnt) {
/* Keep reading so we stay sync'd up. */
if (wrerr == NO) {
if (!wrerr) {
if (atomicio(vwrite, ofd, bp->buf,
count) != count) {
wrerr = YES;
wrerrno = errno;
note_err("%s: %s", np,
strerror(errno));
wrerr = 1;
}
}
count = 0;
cp = bp->buf;
}
}
unset_nonblock(remin);
if (count != 0 && wrerr == NO &&
if (count != 0 && !wrerr &&
atomicio(vwrite, ofd, bp->buf, count) != count) {
wrerr = YES;
wrerrno = errno;
}
if (wrerr == NO && (!exists || S_ISREG(stb.st_mode)) &&
ftruncate(ofd, size) != 0) {
run_err("%s: truncate: %s", np, strerror(errno));
wrerr = DISPLAYED;
note_err("%s: %s", np, strerror(errno));
wrerr = 1;
}
if (!wrerr && (!exists || S_ISREG(stb.st_mode)) &&
ftruncate(ofd, size) != 0)
note_err("%s: truncate: %s", np, strerror(errno));
if (pflag) {
if (exists || omode != mode)
#ifdef HAVE_FCHMOD
if (fchmod(ofd, omode)) {
#else /* HAVE_FCHMOD */
if (chmod(np, omode)) {
#endif /* HAVE_FCHMOD */
run_err("%s: set mode: %s",
note_err("%s: set mode: %s",
np, strerror(errno));
wrerr = DISPLAYED;
}
} else {
if (!exists && omode != mode)
Expand All @@ -1516,36 +1517,25 @@ bad: run_err("%s: %s", np, strerror(errno));
#else /* HAVE_FCHMOD */
if (chmod(np, omode & ~mask)) {
#endif /* HAVE_FCHMOD */
run_err("%s: set mode: %s",
note_err("%s: set mode: %s",
np, strerror(errno));
wrerr = DISPLAYED;
}
}
if (close(ofd) == -1) {
wrerr = YES;
wrerrno = errno;
}
if (close(ofd) == -1)
note_err(np, "%s: close: %s", np, strerror(errno));
(void) response();
if (showprogress)
stop_progress_meter();
if (setimes && wrerr == NO) {
if (setimes && !wrerr) {
setimes = 0;
if (utimes(np, tv) == -1) {
run_err("%s: set times: %s",
note_err("%s: set times: %s",
np, strerror(errno));
wrerr = DISPLAYED;
}
}
switch (wrerr) {
case YES:
run_err("%s: %s", np, strerror(wrerrno));
break;
case NO:
/* If no error was noted then signal success for this file */
if (note_err(NULL) == 0)
(void) atomicio(vwrite, remout, "", 1);
break;
case DISPLAYED:
break;
}
}
done:
for (n = 0; n < npatterns; n++)
Expand Down Expand Up @@ -1633,6 +1623,38 @@ run_err(const char *fmt,...)
}
}

/*
* Notes a sink error for sending at the end of a file transfer. Returns 0 if
* no error has been noted or -1 otherwise. Use note_err(NULL) to flush
* any active error at the end of the transfer.
*/
int
note_err(const char *fmt, ...)
{
static char *emsg;
va_list ap;

/* Replay any previously-noted error */
if (fmt == NULL) {
if (emsg == NULL)
return 0;
run_err("%s", emsg);
free(emsg);
emsg = NULL;
return -1;
}

errs++;
/* Prefer first-noted error */
if (emsg != NULL)
return -1;

va_start(ap, fmt);
vasnmprintf(&emsg, INT_MAX, NULL, fmt, ap);
va_end(ap);
return -1;
}

void
verifydir(char *cp)
{
Expand Down

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