$N in the substitution string!
L flag can be useful in this context to end the
current round of mod_rewrite processing.
++Setting this flag is required to allow a rewrite to continue If the +HTTP request being written has an encoded question mark, '%3f', and the +rewritten result has a '?' in the substiution. This protects from a malicious +URL taking advantage of a capture and re-substitution of the encoded +question mark.
+ ++Setting this flag is required in server-scoped substitutions +start with a variable or backreference and resolve to a filesystem path. +These substitutions are not prefixed with the document root. +This protects from a malicious URL causing the expanded substitution to +map to an unexpected filesystem location. +
+Available Languages: en |
diff --git a/modules/mappers/mod_rewrite.c b/modules/mappers/mod_rewrite.c
index b71c67c..797f093 100644
--- a/modules/mappers/mod_rewrite.c
+++ b/modules/mappers/mod_rewrite.c
@@ -172,6 +172,8 @@ static const char* really_last_key = "rewrite_really_last";
#define RULEFLAG_QSLAST (1<<19)
#define RULEFLAG_QSNONE (1<<20) /* programattic only */
#define RULEFLAG_ESCAPECTLS (1<<21)
+#define RULEFLAG_UNSAFE_PREFIX_STAT (1<<22)
+#define RULEFLAG_UNSAFE_ALLOW3F (1<<23)
/* return code of the rewrite rule
* the result may be escaped - or not
@@ -179,7 +181,7 @@ static const char* really_last_key = "rewrite_really_last";
#define ACTION_NORMAL (1<<0)
#define ACTION_NOESCAPE (1<<1)
#define ACTION_STATUS (1<<2)
-
+#define ACTION_STATUS_SET (1<<3)
#define MAPTYPE_TXT (1<<0)
#define MAPTYPE_DBM (1<<1)
@@ -203,6 +205,7 @@ static const char* really_last_key = "rewrite_really_last";
#define OPTION_IGNORE_INHERIT (1<<8)
#define OPTION_IGNORE_CONTEXT_INFO (1<<9)
#define OPTION_LEGACY_PREFIX_DOCROOT (1<<10)
+#define OPTION_UNSAFE_PREFIX_STAT (1<<12)
#ifndef RAND_MAX
#define RAND_MAX 32767
@@ -296,6 +299,14 @@ typedef enum {
CONDPAT_AP_EXPR
} pattern_type;
+typedef enum {
+ RULE_RC_NOMATCH = 0, /* the rule didn't match */
+ RULE_RC_MATCH = 1, /* a matching rule w/ substitution */
+ RULE_RC_NOSUB = 2, /* a matching rule w/ no substitution */
+ RULE_RC_STATUS_SET = 3 /* a matching rule that has set an HTTP error
+ to be returned in r->status */
+} rule_return_type;
+
typedef struct {
char *input; /* Input string of RewriteCond */
char *pattern; /* the RegExp pattern string */
@@ -927,10 +938,15 @@ static void fully_qualify_uri(request_rec *r)
return;
}
+static int startsWith(request_rec *r, const char *haystack, const char *needle) {
+ int rc = (ap_strstr_c(haystack, needle) == haystack);
+ rewritelog((r, 5, NULL, "prefix_stat startsWith(%s, %s) %d", haystack, needle, rc));
+ return rc;
+}
/*
- * stat() only the first segment of a path
+ * stat() only the first segment of a path, and only if it matches the output of the last matching rule
*/
-static int prefix_stat(const char *path, apr_pool_t *pool)
+static int prefix_stat(request_rec *r, const char *path, apr_pool_t *pool, rewriterule_entry *lastsub)
{
const char *curpath = path;
const char *root;
@@ -964,10 +980,36 @@ static int prefix_stat(const char *path, apr_pool_t *pool)
apr_finfo_t sb;
if (apr_stat(&sb, statpath, APR_FINFO_MIN, pool) == APR_SUCCESS) {
- return 1;
+ if (!lastsub) {
+ rewritelog((r, 3, NULL, "prefix_stat no lastsub subst prefix %s", statpath));
+ return 1;
+ }
+
+ rewritelog((r, 3, NULL, "prefix_stat compare statpath %s and lastsub output %s STATOK %d ",
+ statpath, lastsub->output, lastsub->flags & RULEFLAG_UNSAFE_PREFIX_STAT));
+ if (lastsub->flags & RULEFLAG_UNSAFE_PREFIX_STAT) {
+ return 1;
+ }
+ else {
+ const char *docroot = ap_document_root(r);
+ const char *context_docroot = ap_context_document_root(r);
+ /*
+ * As an example, path (r->filename) is /var/foo/bar/baz.html
+ * even if the flag is not set, we can accept a rule that
+ * began with a literal /var (stapath), or if the entire path
+ * starts with the docroot or context document root
+ */
+ if (startsWith(r, lastsub->output, statpath) ||
+ startsWith(r, path, docroot) ||
+ ((docroot != context_docroot) &&
+ startsWith(r, path, context_docroot))) {
+ return 1;
+ }
+ }
}
}
+ /* prefix will be added */
return 0;
}
@@ -3046,6 +3088,9 @@ static const char *cmd_rewriteoptions(cmd_parms *cmd,
else if (!strcasecmp(w, "legacyprefixdocroot")) {
options |= OPTION_LEGACY_PREFIX_DOCROOT;
}
+ else if (!strcasecmp(w, "UnsafePrefixStat")) {
+ options |= OPTION_UNSAFE_PREFIX_STAT;
+ }
else {
return apr_pstrcat(cmd->pool, "RewriteOptions: unknown option '",
w, "'", NULL);
@@ -3752,6 +3797,18 @@ static const char *cmd_rewriterule_setflag(apr_pool_t *p, void *_cfg,
++error;
}
break;
+ case 'u':
+ case 'U':
+ if (!strcasecmp(key, "nsafePrefixStat")){
+ cfg->flags |= (RULEFLAG_UNSAFE_PREFIX_STAT);
+ }
+ else if(!strcasecmp(key, "nsafeAllow3F")) {
+ cfg->flags |= RULEFLAG_UNSAFE_ALLOW3F;
+ }
+ else {
+ ++error;
+ }
+ break;
default:
++error;
break;
@@ -4102,7 +4159,8 @@ static APR_INLINE void force_type_handler(rewriterule_entry *p,
/*
* Apply a single RewriteRule
*/
-static int apply_rewrite_rule(rewriterule_entry *p, rewrite_ctx *ctx)
+static rule_return_type apply_rewrite_rule(rewriterule_entry *p,
+ rewrite_ctx *ctx)
{
ap_regmatch_t regmatch[AP_MAX_REG_MATCH];
apr_array_header_t *rewriteconds;
@@ -4153,7 +4211,7 @@ static int apply_rewrite_rule(rewriterule_entry *p, rewrite_ctx *ctx)
rc = !ap_regexec(p->regexp, ctx->uri, AP_MAX_REG_MATCH, regmatch, 0);
if (! (( rc && !(p->flags & RULEFLAG_NOTMATCH)) ||
(!rc && (p->flags & RULEFLAG_NOTMATCH)) ) ) {
- return 0;
+ return RULE_RC_NOMATCH;
}
/* It matched, wow! Now it's time to prepare the context structure for
@@ -4204,7 +4262,7 @@ static int apply_rewrite_rule(rewriterule_entry *p, rewrite_ctx *ctx)
}
}
else if (!rc) {
- return 0;
+ return RULE_RC_NOMATCH;
}
/* If some HTTP header was involved in the condition, remember it
@@ -4224,6 +4282,15 @@ static int apply_rewrite_rule(rewriterule_entry *p, rewrite_ctx *ctx)
newuri = do_expand(p->output, ctx, p);
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, '?')) {
+ ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO()
+ "Unsafe URL with %%3f URL rewritten without "
+ "UnsafeAllow3F");
+ r->status = HTTP_FORBIDDEN;
+ return RULE_RC_STATUS_SET;
+ }
}
/* expand [E=var:val] and [CO=