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https://github.com/rkd77/elinks.git
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Reject CR and LF characters in FTP pathnames.
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parent
12d94d3408
commit
4bcce2e5ea
@ -638,6 +638,26 @@ get_ftp_data_socket(struct connection *conn, struct string *command)
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return 1;
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return 1;
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}
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}
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/* Check if the file or directory name @s can be safely sent to the
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* FTP server. To prevent command injection attacks, this function
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* must reject CR LF sequences. */
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static int
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is_ftp_pathname_safe(const struct string *s)
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{
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int i;
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/* RFC 959 says the argument of CWD and RETR is a <pathname>,
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* which consists of <char>s, "any of the 128 ASCII characters
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* except <CR> and <LF>". So other control characters, such
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* as 0x00 and 0x7F, are allowed here. Bytes 0x80...0xFF
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* should not be allowed, but if we reject them, users will
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* probably complain. */
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for (i = 0; i < s->length; i++) {
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if (s->source[i] == 0x0A || s->source[i] == 0x0D)
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return 0;
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}
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return 1;
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}
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/* Create passive socket and add appropriate announcing commands to str. Then
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/* Create passive socket and add appropriate announcing commands to str. Then
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* go and retrieve appropriate object from server.
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* go and retrieve appropriate object from server.
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@ -704,6 +724,13 @@ add_file_cmd_to_str(struct connection *conn)
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add_to_string(&command, "CWD ");
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add_to_string(&command, "CWD ");
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add_uri_to_string(&uri_string, conn->uri, URI_PATH);
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add_uri_to_string(&uri_string, conn->uri, URI_PATH);
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decode_uri_string(&uri_string);
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decode_uri_string(&uri_string);
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if (!is_ftp_pathname_safe(&uri_string)) {
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done_string(&uri_string);
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done_string(&command);
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done_string(&ftp_data_command);
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abort_connection(conn, S_BAD_URL);
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return NULL;
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}
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add_string_to_string(&command, &uri_string);
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add_string_to_string(&command, &uri_string);
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add_crlf_to_string(&command);
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add_crlf_to_string(&command);
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@ -746,6 +773,13 @@ add_file_cmd_to_str(struct connection *conn)
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add_to_string(&command, "RETR ");
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add_to_string(&command, "RETR ");
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add_uri_to_string(&uri_string, conn->uri, URI_PATH);
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add_uri_to_string(&uri_string, conn->uri, URI_PATH);
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decode_uri_string(&uri_string);
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decode_uri_string(&uri_string);
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if (!is_ftp_pathname_safe(&uri_string)) {
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done_string(&uri_string);
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done_string(&command);
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done_string(&ftp_data_command);
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abort_connection(conn, S_BAD_URL);
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return NULL;
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}
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add_string_to_string(&command, &uri_string);
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add_string_to_string(&command, &uri_string);
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add_crlf_to_string(&command);
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add_crlf_to_string(&command);
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done_string(&uri_string);
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done_string(&uri_string);
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