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https://github.com/owasp-modsecurity/ModSecurity.git
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Multipart parsing improvements.
This commit is contained in:
ivanr
parent
e275162463
commit
baf6f59dff
@ -535,6 +535,73 @@ static int multipart_process_boundary(modsec_rec *msr, int last_part, char **err
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return 1;
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}
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static int multipart_boundary_characters_valid(char *boundary) {
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unsigned char *p = (unsigned char *)boundary;
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unsigned char c;
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if (p == NULL) return -1;
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while((c = *p) != '\0') {
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/* Control characters and space not allowed. */
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if (c < 32) {
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return 0;
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}
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/* Non-ASCII characters not allowed. */
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if (c > 126) {
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return 0;
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}
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switch(c) {
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/* Special characters not allowed. */
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case '(' :
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case ')' :
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case '<' :
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case '>' :
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case '@' :
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case ',' :
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case ';' :
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case ':' :
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case '\\' :
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case '"' :
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case '/' :
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case '[' :
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case ']' :
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case '?' :
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case '=' :
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return 0;
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break;
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default :
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/* Do nothing. */
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break;
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}
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p++;
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}
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return 0;
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}
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static int multipart_count_boundary_params(apr_pool_t *mp, const char *header_value) {
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char *duplicate = NULL;
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char *s = NULL;
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int count = 0;
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if (header_value == NULL) return -1;
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duplicate = apr_pstrdup(mp, header_value);
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if (duplicate == NULL) return -1;
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/* Performing a case-insensitive search. */
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strtolower_inplace(duplicate);
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s = duplicate;
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while((s = strstr(s, "boundary")) != NULL) {
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count++;
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s += 8;
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}
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return count;
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}
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/**
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*
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@ -553,23 +620,60 @@ int multipart_init(modsec_rec *msr, char **error_msg) {
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msr->mpd->mpp = NULL;
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if (msr->request_content_type == NULL) {
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msr->mpd->flag_error = 1;
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*error_msg = apr_psprintf(msr->mp, "Multipart: Content-Type header not available.");
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return -1;
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}
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msr->mpd->boundary = strstr(msr->request_content_type, "boundary=");
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if ((msr->mpd->boundary != NULL)&&(*(msr->mpd->boundary + 9) != 0)) {
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char *b = msr->mpd->boundary + 9;
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int len = strlen(b);
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/* Count how many times the word "boundary" appears in the C-T header. */
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if (multipart_count_boundary_params(msr->mp, msr->request_content_type) > 1) {
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msr->mpd->flag_error = 1;
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*error_msg = apr_psprintf(msr->mp, "Multipart: Multiple boundary parameters in C-T.");
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return -1;
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}
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msr->mpd->boundary = strstr(msr->request_content_type, "boundary");
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if (msr->mpd->boundary != NULL) {
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char *b = NULL;
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int len = 0;
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b = strchr(msr->mpd->boundary + 8, '=');
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if (b == NULL) {
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msr->mpd->flag_error = 1;
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*error_msg = apr_psprintf(msr->mp, "Multipart: Invalid boundary in C-T (malformed).");
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return -1;
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}
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/* Check parameter name ends well. */
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if (b != (msr->mpd->boundary + 8)) {
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if (isspace(*(msr->mpd->boundary + 8))) {
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/* Flag for whitespace after parameter name. */
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msr->mpd->flag_boundary_whitespace = 1;
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} else {
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msr->mpd->flag_error = 1;
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*error_msg = apr_psprintf(msr->mp, "Multipart: Invalid boundary in C-T (parameter name).");
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return -1;
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}
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}
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b++; /* Go over the = character. */
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len = strlen(b);
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/* Flag for whitespace before parameter value. */
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if (isspace(*b)) {
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msr->mpd->flag_boundary_whitespace = 1;
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}
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/* Is the boundary quoted? */
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if ((len >= 2)&&(*b == '"')&&(*(b + len - 1) == '"')) {
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/* Quoted. */
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msr->mpd->boundary = apr_pstrndup(msr->mp, b + 1, len - 2);
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if (msr->mpd->boundary == NULL) return -1;
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msr->mpd->flag_boundary_quoted = 1;
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if (strstr(msr->mpd->boundary, "\"") != NULL) {
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*error_msg = apr_psprintf(msr->mp, "Invalid boundary in C-T (quote).");
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msr->mpd->flag_error = 1;
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*error_msg = apr_psprintf(msr->mp, "Multipart: Invalid boundary in C-T (quote).");
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return -1;
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}
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} else {
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@ -579,25 +683,49 @@ int multipart_init(modsec_rec *msr, char **error_msg) {
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if ( (*b == '"')
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|| ((len >= 2)&&(*(b + len - 1) == '"')) )
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{
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*error_msg = apr_psprintf(msr->mp, "Invalid boundary in C-T (quote).");
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msr->mpd->flag_error = 1;
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*error_msg = apr_psprintf(msr->mp, "Multipart: Invalid boundary in C-T (quote).");
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return -1;
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}
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msr->mpd->boundary = apr_pstrdup(msr->mp, b);
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if (msr->mpd->boundary == NULL) return -1;
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msr->mpd->flag_boundary_quoted = 0;
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}
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/* Case-insensitive test for the string "boundary" in the boundary. */
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if (multipart_count_boundary_params(msr->mp, msr->mpd->boundary) != 0) {
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msr->mpd->flag_error = 1;
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*error_msg = apr_psprintf(msr->mp, "Multipart: Invalid boundary in C-T (content).");
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return -1;
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}
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/* Validate the characters used in the boundary. */
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if (multipart_boundary_characters_valid(msr->mpd->boundary) != 1) {
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msr->mpd->flag_error = 1;
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*error_msg = apr_psprintf(msr->mp, "Multipart: Invalid boundary in C-T (characters).");
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return -1;
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}
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msr_log(msr, 9, "Multipart: Boundary%s: %s",
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(msr->mpd->flag_boundary_quoted ? " (quoted)" : ""),
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log_escape_nq(msr->mp, msr->mpd->boundary));
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if (strlen(msr->mpd->boundary) == 0) {
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*error_msg = apr_psprintf(msr->mp, "Multipart boundary in C-T empty.");
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msr->mpd->flag_error = 1;
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*error_msg = apr_psprintf(msr->mp, "Multipart: Invalid boundary in C-T (empty).");
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return -1;
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}
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}
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else {
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*error_msg = apr_psprintf(msr->mp, "Multipart boundary in C-T not found or invalid.");
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/* Test for case-insensitive boundary. Allowed by the RFC but highly unusual. */
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if (multipart_count_boundary_params(msr->mp, msr->request_content_type) > 0) {
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msr->mpd->flag_error = 1;
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*error_msg = apr_psprintf(msr->mp, "Multipart: Invalid boundary in C-T (case sensitivity).");
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return -1;
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}
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*error_msg = apr_psprintf(msr->mp, "Multipart: Boundary not found in C-T.");
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return -1;
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}
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@ -611,7 +739,11 @@ int multipart_complete(modsec_rec *msr, char **error_log) {
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if (msr->mpd == NULL) return 1;
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if ((msr->mpd->seen_data != 0)&&(msr->mpd->is_complete == 0)) {
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*error_log = apr_psprintf(msr->mp, "Multipart: Final boundary missing.");
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if (msr->mpd->boundary_count > 0) {
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*error_log = apr_psprintf(msr->mp, "Multipart: Final boundary missing.");
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} else {
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*error_log = apr_psprintf(msr->mp, "Multipart: No boundaries found in payload.");
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}
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return -1;
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}
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@ -718,6 +850,7 @@ int multipart_process_chunk(modsec_rec *msr, const char *buf,
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}
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processed_as_boundary = 1;
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msr->mpd->boundary_count++;
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}
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else {
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/* error */
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@ -728,9 +861,11 @@ int multipart_process_chunk(modsec_rec *msr, const char *buf,
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return -1;
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}
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} else {
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char *p = NULL;
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/* Check if an attempt to use quotes around the boundary was made. */
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if ( (msr->mpd->flag_boundary_quoted)
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&& (strlen(msr->mpd->buf) >= strlen(msr->mpd->boundary) + 3)
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&& (((*(msr->mpd->buf) == '-'))&&(*(msr->mpd->buf + 1) == '-'))
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&& (*(msr->mpd->buf + 2) == '"')
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&& (strncmp(msr->mpd->buf + 3, msr->mpd->boundary, strlen(msr->mpd->boundary)) == 0)
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) {
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@ -739,6 +874,21 @@ int multipart_process_chunk(modsec_rec *msr, const char *buf,
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return -1;
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}
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/* Check the beginning of the boundary for whitespace. */
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p = msr->mpd->buf + 2;
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while(isspace(*p)) {
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p++;
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}
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if ( (p != msr->mpd->buf)
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&& (strncmp(p, msr->mpd->boundary, strlen(msr->mpd->boundary)))
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) {
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/* Found whitespace at the beginning of the boundary. */
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msr->mpd->flag_error = 1;
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*error_msg = apr_psprintf(msr->mp, "Multipart: Invalid boundary (whitespace).");
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return -1;
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}
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msr->mpd->flag_unmatched_boundary = 1;
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}
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}
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@ -61,9 +61,10 @@ struct multipart_data {
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apr_array_header_t *parts;
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/* mime boundary used to detect when
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* parts end and new begin
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* parts end and begin
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*/
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char *boundary;
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int boundary_count;
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/* internal buffer and other variables
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* used while parsing
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@ -84,7 +85,7 @@ struct multipart_data {
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/* part parsing state; 0 means we are reading
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* headers, 1 means we are collecting data
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*/
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int mpp_state;
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int mpp_state;
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/* because of the way this parsing algorithm
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* works we hold back the last two bytes of
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@ -93,18 +94,19 @@ struct multipart_data {
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* a boundary; the first byte is an indicator
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* 0 - no content, 1 - two data bytes available
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*/
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char reserve[4];
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char reserve[4];
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int seen_data;
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int is_complete;
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int seen_data;
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int is_complete;
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int flag_error;
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int flag_data_before;
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int flag_data_after;
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int flag_header_folding;
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int flag_boundary_quoted;
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int flag_lf_line;
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int flag_unmatched_boundary;
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int flag_error;
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int flag_data_before;
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int flag_data_after;
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int flag_header_folding;
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int flag_boundary_quoted;
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int flag_lf_line;
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int flag_unmatched_boundary;
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int flag_boundary_whitespace;
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};
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@ -1240,6 +1240,18 @@ static int var_multipart_boundary_quoted_generate(modsec_rec *msr, msre_var *var
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}
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}
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/* MULTIPART_BOUNDARY_WHITESPACE */
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static int var_multipart_boundary_whitespace_generate(modsec_rec *msr, msre_var *var, msre_rule *rule,
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apr_table_t *vartab, apr_pool_t *mptmp)
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{
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if ((msr->mpd != NULL)&&(msr->mpd->flag_boundary_whitespace != 0)) {
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return var_simple_generate(var, vartab, mptmp, "1");
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} else {
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return var_simple_generate(var, vartab, mptmp, "0");
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}
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}
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/* MULTIPART_DATA_AFTER */
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static int var_multipart_data_after_generate(modsec_rec *msr, msre_var *var, msre_rule *rule,
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@ -1297,6 +1309,7 @@ static int var_multipart_strict_error_generate(modsec_rec *msr, msre_var *var, m
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/* Respond positive if at least one of the multipart flags is raised. */
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if ( (msr->mpd->flag_error)
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||(msr->mpd->flag_boundary_quoted != 0)
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||(msr->mpd->flag_boundary_whitespace != 0)
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||(msr->mpd->flag_data_before != 0)
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||(msr->mpd->flag_data_after != 0)
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||(msr->mpd->flag_header_folding != 0)
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@ -2264,6 +2277,17 @@ void msre_engine_register_default_variables(msre_engine *engine) {
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PHASE_REQUEST_BODY
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);
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/* MULTIPART_BOUNDARY_WHITESPACE */
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msre_engine_variable_register(engine,
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"MULTIPART_BOUNDARY_WHITESPACE",
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VAR_SIMPLE,
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0, 0,
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NULL,
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var_multipart_boundary_whitespace_generate,
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VAR_CACHE,
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PHASE_REQUEST_BODY
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);
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/* MULTIPART_DATA_AFTER */
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msre_engine_variable_register(engine,
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"MULTIPART_DATA_AFTER",
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