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httpd/httpd-2.4.62-r1919325.patch

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From a0a68b99d131741c1867cff321424892838fc4b3 Mon Sep 17 00:00:00 2001
From: Yann Ylavic <ylavic@apache.org>
Date: Sat, 27 Jul 2024 13:35:53 +0000
Subject: [PATCH] mod_rewrite: Better question mark tracking to avoid
UnsafeAllow3F. PR 69197.
Track in do_expand() whether a '?' in the uri-path comes from a literal in
the substitution string or from an expansion (variable, lookup, ...).
In the former case it's safe to assume that it's the query-string separator
but for the other case it's not (could be a decoded %3f from r->uri).
This allows to avoid [UnsafeAllow3F] for most cases.
Merges r1919325 from trunk
Reviewed by: ylavic, covener, jorton
Github: closes #462
git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1919545 13f79535-47bb-0310-9956-ffa450edef68
---
modules/mappers/mod_rewrite.c | 107 ++++++++++++++++++++++++++++------
1 file changed, 89 insertions(+), 18 deletions(-)
diff --git a/modules/mappers/mod_rewrite.c b/modules/mappers/mod_rewrite.c
index f1c22e3235b..53fb1e91ffb 100644
--- a/modules/mappers/mod_rewrite.c
+++ b/modules/mappers/mod_rewrite.c
@@ -2376,9 +2376,16 @@ static APR_INLINE char *find_char_in_curlies(char *s, int c)
* of an earlier expansion to include expansion specifiers that
* are interpreted by a later expansion, producing results that
* were not intended by the administrator.
+ *
+ * unsafe_qmark if not NULL will be set to 1 or 0 if a question mark
+ * is found respectively in a literal or in a lookup/expansion (whether
+ * it's the first or last qmark depends on [QSL]). Should be initialized
+ * to -1 and remains so if no qmark is found.
*/
-static char *do_expand(char *input, rewrite_ctx *ctx, rewriterule_entry *entry)
+static char *do_expand(char *input, rewrite_ctx *ctx, rewriterule_entry *entry,
+ int *unsafe_qmark)
{
+#define EXPAND_SPECIALS "\\$%"
result_list *result, *current;
result_list sresult[SMALL_EXPANSION];
unsigned spc = 0;
@@ -2386,8 +2393,29 @@ static char *do_expand(char *input, rewrite_ctx *ctx, rewriterule_entry *entry)
char *p, *c;
apr_pool_t *pool = ctx->r->pool;
- span = strcspn(input, "\\$%");
inputlen = strlen(input);
+ if (!unsafe_qmark) {
+ span = strcspn(input, EXPAND_SPECIALS);
+ }
+ else {
+ span = strcspn(input, EXPAND_SPECIALS "?");
+ if (input[span] == '?') {
+ /* this qmark is not from an expansion thus safe */
+ *unsafe_qmark = 0;
+
+ /* keep tracking only if interested in the last qmark */
+ if (entry && (entry->flags & RULEFLAG_QSLAST)) {
+ do {
+ span++;
+ span += strcspn(input + span, EXPAND_SPECIALS "?");
+ } while (input[span] == '?');
+ }
+ else {
+ unsafe_qmark = NULL;
+ span += strcspn(input + span, EXPAND_SPECIALS);
+ }
+ }
+ }
/* fast exit */
if (inputlen == span) {
@@ -2405,6 +2433,8 @@ static char *do_expand(char *input, rewrite_ctx *ctx, rewriterule_entry *entry)
/* loop for specials */
do {
+ int expanded = 0;
+
/* prepare next entry */
if (current->len) {
current->next = (spc < SMALL_EXPANSION)
@@ -2450,6 +2480,8 @@ static char *do_expand(char *input, rewrite_ctx *ctx, rewriterule_entry *entry)
current->len = span;
current->string = p;
outlen += span;
+
+ expanded = 1;
p = endp + 1;
}
@@ -2489,19 +2521,18 @@ static char *do_expand(char *input, rewrite_ctx *ctx, rewriterule_entry *entry)
}
/* reuse of key variable as result */
- key = lookup_map(ctx->r, map, do_expand(key, ctx, entry));
-
+ key = lookup_map(ctx->r, map, do_expand(key, ctx, entry, NULL));
if (!key && dflt && *dflt) {
- key = do_expand(dflt, ctx, entry);
+ key = do_expand(dflt, ctx, entry, NULL);
}
-
- if (key) {
+ if (key && *key) {
span = strlen(key);
current->len = span;
current->string = key;
outlen += span;
}
+ expanded = 1;
p = endp + 1;
}
}
@@ -2531,8 +2562,9 @@ static char *do_expand(char *input, rewrite_ctx *ctx, rewriterule_entry *entry)
current->len = span;
current->string = bri->source + bri->regmatch[n].rm_so;
}
-
outlen += span;
+
+ expanded = 1;
}
p += 2;
@@ -2545,8 +2577,41 @@ static char *do_expand(char *input, rewrite_ctx *ctx, rewriterule_entry *entry)
++outlen;
}
+ if (unsafe_qmark && expanded && current->len
+ && memchr(current->string, '?', current->len)) {
+ /* this qmark is from an expansion thus unsafe */
+ *unsafe_qmark = 1;
+
+ /* keep tracking only if interested in the last qmark */
+ if (!entry || !(entry->flags & RULEFLAG_QSLAST)) {
+ unsafe_qmark = NULL;
+ }
+ }
+
/* check the remainder */
- if (*p && (span = strcspn(p, "\\$%")) > 0) {
+ if (!unsafe_qmark) {
+ span = strcspn(p, EXPAND_SPECIALS);
+ }
+ else {
+ span = strcspn(p, EXPAND_SPECIALS "?");
+ if (p[span] == '?') {
+ /* this qmark is not from an expansion thus safe */
+ *unsafe_qmark = 0;
+
+ /* keep tracking only if interested in the last qmark */
+ if (entry && (entry->flags & RULEFLAG_QSLAST)) {
+ do {
+ span++;
+ span += strcspn(p + span, EXPAND_SPECIALS "?");
+ } while (p[span] == '?');
+ }
+ else {
+ unsafe_qmark = NULL;
+ span += strcspn(p + span, EXPAND_SPECIALS);
+ }
+ }
+ }
+ if (span > 0) {
if (current->len) {
current->next = (spc < SMALL_EXPANSION)
? &(sresult[spc++])
@@ -2591,7 +2656,7 @@ static void do_expand_env(data_item *env, rewrite_ctx *ctx)
char *name, *val;
while (env) {
- name = do_expand(env->data, ctx, NULL);
+ name = do_expand(env->data, ctx, NULL, NULL);
if (*name == '!') {
name++;
apr_table_unset(ctx->r->subprocess_env, name);
@@ -2725,7 +2790,7 @@ static void add_cookie(request_rec *r, char *s)
static void do_expand_cookie(data_item *cookie, rewrite_ctx *ctx)
{
while (cookie) {
- add_cookie(ctx->r, do_expand(cookie->data, ctx, NULL));
+ add_cookie(ctx->r, do_expand(cookie->data, ctx, NULL, NULL));
cookie = cookie->next;
}
@@ -4014,7 +4079,7 @@ static int apply_rewrite_cond(rewritecond_entry *p, rewrite_ctx *ctx)
int basis;
if (p->ptype != CONDPAT_AP_EXPR)
- input = do_expand(p->input, ctx, NULL);
+ input = do_expand(p->input, ctx, NULL, NULL);
switch (p->ptype) {
case CONDPAT_FILE_EXISTS:
@@ -4178,7 +4243,7 @@ static APR_INLINE void force_type_handler(rewriterule_entry *p,
char *expanded;
if (p->forced_mimetype) {
- expanded = do_expand(p->forced_mimetype, ctx, p);
+ expanded = do_expand(p->forced_mimetype, ctx, p, NULL);
if (*expanded) {
ap_str_tolower(expanded);
@@ -4192,7 +4257,7 @@ static APR_INLINE void force_type_handler(rewriterule_entry *p,
}
if (p->forced_handler) {
- expanded = do_expand(p->forced_handler, ctx, p);
+ expanded = do_expand(p->forced_handler, ctx, p, NULL);
if (*expanded) {
ap_str_tolower(expanded);
@@ -4329,12 +4394,18 @@ static rule_return_type apply_rewrite_rule(rewriterule_entry *p,
/* expand the result */
if (!(p->flags & RULEFLAG_NOSUB)) {
- newuri = do_expand(p->output, ctx, p);
+ int unsafe_qmark = -1;
+
+ if (p->flags & RULEFLAG_UNSAFE_ALLOW3F) {
+ newuri = do_expand(p->output, ctx, p, NULL);
+ }
+ else {
+ newuri = do_expand(p->output, ctx, p, &unsafe_qmark);
+ }
rewritelog((r, 2, ctx->perdir, "rewrite '%s' -> '%s'", ctx->uri,
newuri));
- if (!(p->flags & RULEFLAG_UNSAFE_ALLOW3F) &&
- ap_strcasestr(r->unparsed_uri, "%3f") &&
- ap_strchr_c(newuri, '?')) {
+
+ if (unsafe_qmark > 0) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(10508)
"Unsafe URL with %%3f URL rewritten without "
"UnsafeAllow3F");
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