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upstream: when checking that filenames sent by the server side

match what the client requested, be prepared to handle shell-style brace
alternations, e.g. "{foo,bar}".

"looks good to me" millert@ + in snaps for the last week courtesy
deraadt@

OpenBSD-Commit-ID: 3b1ce7639b0b25b2248e3a30f561a548f6815f3e
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djmdjm committed Feb 10, 2019
1 parent 318e4f8 commit 3d896c157c722bc47adca51a58dca859225b5874
Showing with 270 additions and 12 deletions.
  1. +270 −12 scp.c
282 scp.c
@@ -1,4 +1,4 @@
/* $OpenBSD: scp.c,v 1.203 2019/01/27 07:14:11 jmc Exp $ */
/* $OpenBSD: scp.c,v 1.204 2019/02/10 11:15:52 djm Exp $ */
/*
* scp - secure remote copy. This is basically patched BSD rcp which
* uses ssh to do the data transfer (instead of using rcmd).
@@ -630,6 +630,253 @@ parse_scp_uri(const char *uri, char **userp, char **hostp, int *portp,
return r;
}

/* Appends a string to an array; returns 0 on success, -1 on alloc failure */
static int
append(char *cp, char ***ap, size_t *np)
{
char **tmp;

if ((tmp = reallocarray(*ap, *np + 1, sizeof(*tmp))) == NULL)
return -1;
tmp[(*np)] = cp;
(*np)++;
*ap = tmp;
return 0;
}

/*
* Finds the start and end of the first brace pair in the pattern.
* returns 0 on success or -1 for invalid patterns.
*/
static int
find_brace(const char *pattern, int *startp, int *endp)
{
int i;
int in_bracket, brace_level;

*startp = *endp = -1;
in_bracket = brace_level = 0;
for (i = 0; i < INT_MAX && *endp < 0 && pattern[i] != '\0'; i++) {
switch (pattern[i]) {
case '\\':
/* skip next character */
if (pattern[i + 1] != '\0')
i++;
break;
case '[':
in_bracket = 1;
break;
case ']':
in_bracket = 0;
break;
case '{':
if (in_bracket)
break;
if (pattern[i + 1] == '}') {
/* Protect a single {}, for find(1), like csh */
i++; /* skip */
break;
}
if (*startp == -1)
*startp = i;
brace_level++;
break;
case '}':
if (in_bracket)
break;
if (*startp < 0) {
/* Unbalanced brace */
return -1;
}
if (--brace_level <= 0)
*endp = i;
break;
}
}
/* unbalanced brackets/braces */
if (*endp < 0 && (*startp >= 0 || in_bracket))
return -1;
return 0;
}

/*
* Assembles and records a successfully-expanded pattern, returns -1 on
* alloc failure.
*/
static int
emit_expansion(const char *pattern, int brace_start, int brace_end,
int sel_start, int sel_end, char ***patternsp, size_t *npatternsp)
{
char *cp;
int o = 0, tail_len = strlen(pattern + brace_end + 1);

if ((cp = malloc(brace_start + (sel_end - sel_start) +
tail_len + 1)) == NULL)
return -1;

/* Pattern before initial brace */
if (brace_start > 0) {
memcpy(cp, pattern, brace_start);
o = brace_start;
}
/* Current braced selection */
if (sel_end - sel_start > 0) {
memcpy(cp + o, pattern + sel_start,
sel_end - sel_start);
o += sel_end - sel_start;
}
/* Remainder of pattern after closing brace */
if (tail_len > 0) {
memcpy(cp + o, pattern + brace_end + 1, tail_len);
o += tail_len;
}
cp[o] = '\0';
if (append(cp, patternsp, npatternsp) != 0) {
free(cp);
return -1;
}
return 0;
}

/*
* Expand the first encountered brace in pattern, appending the expanded
* patterns it yielded to the *patternsp array.
*
* Returns 0 on success or -1 on allocation failure.
*
* Signals whether expansion was performed via *expanded and whether
* pattern was invalid via *invalid.
*/
static int
brace_expand_one(const char *pattern, char ***patternsp, size_t *npatternsp,
int *expanded, int *invalid)
{
int i;
int in_bracket, brace_start, brace_end, brace_level;
int sel_start, sel_end;

*invalid = *expanded = 0;

if (find_brace(pattern, &brace_start, &brace_end) != 0) {
*invalid = 1;
return 0;
} else if (brace_start == -1)
return 0;

in_bracket = brace_level = 0;
for (i = sel_start = brace_start + 1; i < brace_end; i++) {
switch (pattern[i]) {
case '{':
if (in_bracket)
break;
brace_level++;
break;
case '}':
if (in_bracket)
break;
brace_level--;
break;
case '[':
in_bracket = 1;
break;
case ']':
in_bracket = 0;
break;
case '\\':
if (i < brace_end - 1)
i++; /* skip */
break;
}
if (pattern[i] == ',' || i == brace_end - 1) {
if (in_bracket || brace_level > 0)
continue;
/* End of a selection, emit an expanded pattern */

/* Adjust end index for last selection */
sel_end = (i == brace_end - 1) ? brace_end : i;
if (emit_expansion(pattern, brace_start, brace_end,
sel_start, sel_end, patternsp, npatternsp) != 0)
return -1;
/* move on to the next selection */
sel_start = i + 1;
continue;
}
}
if (in_bracket || brace_level > 0) {
*invalid = 1;
return 0;
}
/* success */
*expanded = 1;
return 0;
}

/* Expand braces from pattern. Returns 0 on success, -1 on failure */
static int
brace_expand(const char *pattern, char ***patternsp, size_t *npatternsp)
{
char *cp, *cp2, **active = NULL, **done = NULL;
size_t i, nactive = 0, ndone = 0;
int ret = -1, invalid = 0, expanded = 0;

*patternsp = NULL;
*npatternsp = 0;

/* Start the worklist with the original pattern */
if ((cp = strdup(pattern)) == NULL)
return -1;
if (append(cp, &active, &nactive) != 0) {
free(cp);
return -1;
}
while (nactive > 0) {
cp = active[nactive - 1];
nactive--;
if (brace_expand_one(cp, &active, &nactive,
&expanded, &invalid) == -1) {
free(cp);
goto fail;
}
if (invalid)
fatal("%s: invalid brace pattern \"%s\"", __func__, cp);
if (expanded) {
/*
* Current entry expanded to new entries on the
* active list; discard the progenitor pattern.
*/
free(cp);
continue;
}
/*
* Pattern did not expand; append the finename component to
* the completed list
*/
if ((cp2 = strrchr(cp, '/')) != NULL)
*cp2++ = '\0';
else
cp2 = cp;
if (append(xstrdup(cp2), &done, &ndone) != 0) {
free(cp);
goto fail;
}
free(cp);
}
/* success */
*patternsp = done;
*npatternsp = ndone;
done = NULL;
ndone = 0;
ret = 0;
fail:
for (i = 0; i < nactive; i++)
free(active[i]);
free(active);
for (i = 0; i < ndone; i++)
free(done[i]);
free(done);
return ret;
}

void
toremote(int argc, char **argv)
{
@@ -993,7 +1240,8 @@ sink(int argc, char **argv, const char *src)
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;
char **patterns = NULL;
size_t n, npatterns = 0;
struct timeval tv[2];

#define atime tv[0]
@@ -1023,16 +1271,13 @@ sink(int argc, char **argv, const char *src)
* 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';
}
if (brace_expand(src, &patterns, &npatterns) != 0)
fatal("%s: could not expand pattern", __func__);
}
for (first = 1;; first = 0) {
cp = buf;
if (atomicio(read, remin, cp, 1) != 1)
return;
goto done;
if (*cp++ == '\n')
SCREWUP("unexpected <newline>");
do {
@@ -1058,7 +1303,7 @@ sink(int argc, char **argv, const char *src)
}
if (buf[0] == 'E') {
(void) atomicio(vwrite, remout, "", 1);
return;
goto done;
}
if (ch == '\n')
*--cp = 0;
@@ -1133,9 +1378,14 @@ sink(int argc, char **argv, const char *src)
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 (npatterns > 0) {
for (n = 0; n < npatterns; n++) {
if (fnmatch(patterns[n], cp, 0) == 0)
break;
}
if (n >= npatterns)
SCREWUP("filename does not match request");
}
if (targisdir) {
static char *namebuf;
static size_t cursize;
@@ -1294,7 +1544,15 @@ bad: run_err("%s: %s", np, strerror(errno));
break;
}
}
done:
for (n = 0; n < npatterns; n++)
free(patterns[n]);
free(patterns);
return;
screwup:
for (n = 0; n < npatterns; n++)
free(patterns[n]);
free(patterns);
run_err("protocol error: %s", why);
exit(1);
}

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