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app-layer-smtp.c
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app-layer-smtp.c
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/* Copyright (C) 2007-2021 Open Information Security Foundation
*
* You can copy, redistribute or modify this Program under the terms of
* the GNU General Public License version 2 as published by the Free
* Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* version 2 along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
/**
* \file
*
* \author Anoop Saldanha <anoopsaldanha@gmail.com>
*/
#include "suricata.h"
#include "suricata-common.h"
#include "decode.h"
#include "threads.h"
#include "stream-tcp-private.h"
#include "stream-tcp-reassemble.h"
#include "stream-tcp.h"
#include "stream.h"
#include "app-layer.h"
#include "app-layer-detect-proto.h"
#include "app-layer-protos.h"
#include "app-layer-parser.h"
#include "app-layer-smtp.h"
#include "util-enum.h"
#include "util-mpm.h"
#include "util-debug.h"
#include "util-print.h"
#include "util-byte.h"
#include "util-unittest.h"
#include "util-unittest-helper.h"
#include "util-memcmp.h"
#include "flow-util.h"
#include "detect-engine.h"
#include "detect-engine-state.h"
#include "detect-engine-build.h"
#include "detect-parse.h"
#include "decode-events.h"
#include "conf.h"
#include "util-mem.h"
#include "util-misc.h"
#include "util-validate.h"
/* content-limit default value */
#define FILEDATA_CONTENT_LIMIT 100000
/* content-inspect-min-size default value */
#define FILEDATA_CONTENT_INSPECT_MIN_SIZE 32768
/* content-inspect-window default value */
#define FILEDATA_CONTENT_INSPECT_WINDOW 4096
/* raw extraction default value */
#define SMTP_RAW_EXTRACTION_DEFAULT_VALUE false
#define SMTP_MAX_REQUEST_AND_REPLY_LINE_LENGTH 510
#define SMTP_COMMAND_BUFFER_STEPS 5
/* we are in process of parsing a fresh command. Just a placeholder. If we
* are not in STATE_COMMAND_DATA_MODE, we have to be in this mode */
#define SMTP_PARSER_STATE_COMMAND_MODE 0x00
/* we are in mode of parsing a command's data. Used when we are parsing tls
* or accepting the rfc 2822 mail after DATA command */
#define SMTP_PARSER_STATE_COMMAND_DATA_MODE 0x01
/* Used when we are still in the process of parsing a server command. Used
* with multi-line replies and the stream is fragmented before all the lines
* for a response is seen */
#define SMTP_PARSER_STATE_PARSING_SERVER_RESPONSE 0x02
/* Used to indicate that the parser has seen the first reply */
#define SMTP_PARSER_STATE_FIRST_REPLY_SEEN 0x04
/* Used to indicate that the parser is parsing a multiline reply */
#define SMTP_PARSER_STATE_PARSING_MULTILINE_REPLY 0x08
/* Used to indicate that the server supports pipelining */
#define SMTP_PARSER_STATE_PIPELINING_SERVER 0x10
/* Various SMTP commands
* We currently have var-ified just STARTTLS and DATA, since we need to them
* for state transitions. The rest are just indicate as OTHER_CMD. Other
* commands would be introduced as and when needed */
#define SMTP_COMMAND_STARTTLS 1
#define SMTP_COMMAND_DATA 2
#define SMTP_COMMAND_BDAT 3
/* not an actual command per se, but the mode where we accept the mail after
* DATA has it's own reply code for completion, from the server. We give this
* stage a pseudo command of it's own, so that we can add this to the command
* buffer to match with the reply */
#define SMTP_COMMAND_DATA_MODE 4
/* All other commands are represented by this var */
#define SMTP_COMMAND_OTHER_CMD 5
#define SMTP_COMMAND_RSET 6
/* Different EHLO extensions. Not used now. */
#define SMTP_EHLO_EXTENSION_PIPELINING
#define SMTP_EHLO_EXTENSION_SIZE
#define SMTP_EHLO_EXTENSION_DSN
#define SMTP_EHLO_EXTENSION_STARTTLS
#define SMTP_EHLO_EXTENSION_8BITMIME
/* Limit till the data would be buffered in current line */
#define SMTP_LINE_BUFFER_LIMIT 4096
typedef struct SMTPInput_ {
/* current input that is being parsed */
const uint8_t *buf;
int32_t len;
/* original length of an input */
int32_t orig_len;
/* Consumed bytes till current line */
int32_t consumed;
} SMTPInput;
typedef struct SMTPLine_ {
/** current line extracted by the parser from the call to SMTPGetline() */
const uint8_t *buf;
/** length of the line in current_line. Doesn't include the delimiter */
int32_t len;
uint8_t delim_len;
} SMTPLine;
SCEnumCharMap smtp_decoder_event_table[] = {
{ "INVALID_REPLY", SMTP_DECODER_EVENT_INVALID_REPLY },
{ "UNABLE_TO_MATCH_REPLY_WITH_REQUEST", SMTP_DECODER_EVENT_UNABLE_TO_MATCH_REPLY_WITH_REQUEST },
{ "MAX_COMMAND_LINE_LEN_EXCEEDED", SMTP_DECODER_EVENT_MAX_COMMAND_LINE_LEN_EXCEEDED },
{ "MAX_REPLY_LINE_LEN_EXCEEDED", SMTP_DECODER_EVENT_MAX_REPLY_LINE_LEN_EXCEEDED },
{ "INVALID_PIPELINED_SEQUENCE", SMTP_DECODER_EVENT_INVALID_PIPELINED_SEQUENCE },
{ "BDAT_CHUNK_LEN_EXCEEDED", SMTP_DECODER_EVENT_BDAT_CHUNK_LEN_EXCEEDED },
{ "NO_SERVER_WELCOME_MESSAGE", SMTP_DECODER_EVENT_NO_SERVER_WELCOME_MESSAGE },
{ "TLS_REJECTED", SMTP_DECODER_EVENT_TLS_REJECTED },
{ "DATA_COMMAND_REJECTED", SMTP_DECODER_EVENT_DATA_COMMAND_REJECTED },
{ "FAILED_PROTOCOL_CHANGE", SMTP_DECODER_EVENT_FAILED_PROTOCOL_CHANGE },
/* MIME Events */
{ "MIME_PARSE_FAILED", SMTP_DECODER_EVENT_MIME_PARSE_FAILED },
{ "MIME_MALFORMED_MSG", SMTP_DECODER_EVENT_MIME_MALFORMED_MSG },
{ "MIME_INVALID_BASE64", SMTP_DECODER_EVENT_MIME_INVALID_BASE64 },
{ "MIME_INVALID_QP", SMTP_DECODER_EVENT_MIME_INVALID_QP },
{ "MIME_LONG_LINE", SMTP_DECODER_EVENT_MIME_LONG_LINE },
{ "MIME_LONG_ENC_LINE", SMTP_DECODER_EVENT_MIME_LONG_ENC_LINE },
{ "MIME_LONG_HEADER_NAME", SMTP_DECODER_EVENT_MIME_LONG_HEADER_NAME },
{ "MIME_LONG_HEADER_VALUE", SMTP_DECODER_EVENT_MIME_LONG_HEADER_VALUE },
{ "MIME_LONG_BOUNDARY", SMTP_DECODER_EVENT_MIME_BOUNDARY_TOO_LONG },
{ "MIME_LONG_FILENAME", SMTP_DECODER_EVENT_MIME_LONG_FILENAME },
/* Invalid behavior or content */
{ "DUPLICATE_FIELDS", SMTP_DECODER_EVENT_DUPLICATE_FIELDS },
{ "UNPARSABLE_CONTENT", SMTP_DECODER_EVENT_UNPARSABLE_CONTENT },
{ "TRUNCATED_LINE", SMTP_DECODER_EVENT_TRUNCATED_LINE },
{ NULL, -1 },
};
typedef struct SMTPThreadCtx_ {
MpmThreadCtx *smtp_mpm_thread_ctx;
PrefilterRuleStore *pmq;
} SMTPThreadCtx;
#define SMTP_MPM mpm_default_matcher
static MpmCtx *smtp_mpm_ctx = NULL;
/* smtp reply codes. If an entry is made here, please make a simultaneous
* entry in smtp_reply_map */
enum SMTPCode {
SMTP_REPLY_211,
SMTP_REPLY_214,
SMTP_REPLY_220,
SMTP_REPLY_221,
SMTP_REPLY_235,
SMTP_REPLY_250,
SMTP_REPLY_251,
SMTP_REPLY_252,
SMTP_REPLY_334,
SMTP_REPLY_354,
SMTP_REPLY_421,
SMTP_REPLY_450,
SMTP_REPLY_451,
SMTP_REPLY_452,
SMTP_REPLY_455,
SMTP_REPLY_500,
SMTP_REPLY_501,
SMTP_REPLY_502,
SMTP_REPLY_503,
SMTP_REPLY_504,
SMTP_REPLY_550,
SMTP_REPLY_551,
SMTP_REPLY_552,
SMTP_REPLY_553,
SMTP_REPLY_554,
SMTP_REPLY_555,
};
SCEnumCharMap smtp_reply_map[ ] = {
{ "211", SMTP_REPLY_211 },
{ "214", SMTP_REPLY_214 },
{ "220", SMTP_REPLY_220 },
{ "221", SMTP_REPLY_221 },
{ "235", SMTP_REPLY_235 },
{ "250", SMTP_REPLY_250 },
{ "251", SMTP_REPLY_251 },
{ "252", SMTP_REPLY_252 },
{ "334", SMTP_REPLY_334 },
{ "354", SMTP_REPLY_354 },
{ "421", SMTP_REPLY_421 },
{ "450", SMTP_REPLY_450 },
{ "451", SMTP_REPLY_451 },
{ "452", SMTP_REPLY_452 },
{ "455", SMTP_REPLY_455 },
{ "500", SMTP_REPLY_500 },
{ "501", SMTP_REPLY_501 },
{ "502", SMTP_REPLY_502 },
{ "503", SMTP_REPLY_503 },
{ "504", SMTP_REPLY_504 },
{ "550", SMTP_REPLY_550 },
{ "551", SMTP_REPLY_551 },
{ "552", SMTP_REPLY_552 },
{ "553", SMTP_REPLY_553 },
{ "554", SMTP_REPLY_554 },
{ "555", SMTP_REPLY_555 },
{ NULL, -1 },
};
/* Create SMTP config structure */
SMTPConfig smtp_config = { false, { false, false, false, NULL, false, false, 0 }, 0, 0, 0, false,
STREAMING_BUFFER_CONFIG_INITIALIZER };
static SMTPString *SMTPStringAlloc(void);
/**
* \brief Configure SMTP Mime Decoder by parsing out mime section of YAML
* config file
*
* \return none
*/
static void SMTPConfigure(void) {
SCEnter();
intmax_t imval;
uint32_t content_limit = 0;
uint32_t content_inspect_min_size = 0;
uint32_t content_inspect_window = 0;
ConfNode *config = ConfGetNode("app-layer.protocols.smtp.mime");
if (config != NULL) {
ConfNode *extract_urls_schemes = NULL;
int val;
int ret = ConfGetChildValueBool(config, "decode-mime", &val);
if (ret) {
smtp_config.decode_mime = val;
}
ret = ConfGetChildValueBool(config, "decode-base64", &val);
if (ret) {
smtp_config.mime_config.decode_base64 = val;
}
ret = ConfGetChildValueBool(config, "decode-quoted-printable", &val);
if (ret) {
smtp_config.mime_config.decode_quoted_printable = val;
}
ret = ConfGetChildValueInt(config, "header-value-depth", &imval);
if (ret) {
smtp_config.mime_config.header_value_depth = (uint32_t) imval;
}
ret = ConfGetChildValueBool(config, "extract-urls", &val);
if (ret) {
smtp_config.mime_config.extract_urls = val;
}
/* Parse extract-urls-schemes from mime config, add '://' suffix to found schemes,
* and provide a default value of 'http' for the schemes to be extracted
* if no schemes are found in the config */
extract_urls_schemes = ConfNodeLookupChild(config, "extract-urls-schemes");
if (extract_urls_schemes) {
ConfNode *scheme = NULL;
TAILQ_FOREACH (scheme, &extract_urls_schemes->head, next) {
/* new_val_len: scheme value from config e.g. 'http' + '://' + null terminator */
size_t new_val_len = strlen(scheme->val) + 3 + 1;
if (new_val_len > UINT16_MAX) {
FatalError("Too long value for extract-urls-schemes");
}
char *new_val = SCMalloc(new_val_len);
if (unlikely(new_val == NULL)) {
FatalError("SCMalloc failure.");
}
int r = snprintf(new_val, new_val_len, "%s://", scheme->val);
if (r < 0 || r >= (int)new_val_len) {
FatalError("snprintf failure.");
}
/* replace existing scheme value stored on the linked list with new value including
* '://' suffix */
SCFree(scheme->val);
scheme->val = new_val;
}
smtp_config.mime_config.extract_urls_schemes = extract_urls_schemes;
} else {
/* Add default extract url scheme 'http' since
* extract-urls-schemes wasn't found in the config */
ConfNode *seq_node = ConfNodeNew();
if (unlikely(seq_node == NULL)) {
FatalError("ConfNodeNew failure.");
}
ConfNode *scheme = ConfNodeNew();
if (unlikely(scheme == NULL)) {
FatalError("ConfNodeNew failure.");
}
seq_node->name = SCStrdup("extract-urls-schemes");
if (unlikely(seq_node->name == NULL)) {
FatalError("SCStrdup failure.");
}
scheme->val = SCStrdup("http://");
if (unlikely(scheme->val == NULL)) {
FatalError("SCStrdup failure.");
}
seq_node->is_seq = 1;
TAILQ_INSERT_TAIL(&seq_node->head, scheme, next);
TAILQ_INSERT_TAIL(&config->head, seq_node, next);
smtp_config.mime_config.extract_urls_schemes = seq_node;
}
ret = ConfGetChildValueBool(config, "log-url-scheme", &val);
if (ret) {
smtp_config.mime_config.log_url_scheme = val;
}
ret = ConfGetChildValueBool(config, "body-md5", &val);
if (ret) {
smtp_config.mime_config.body_md5 = val;
}
}
/* Pass mime config data to MimeDec API */
MimeDecSetConfig(&smtp_config.mime_config);
smtp_config.content_limit = FILEDATA_CONTENT_LIMIT;
smtp_config.content_inspect_window = FILEDATA_CONTENT_INSPECT_WINDOW;
smtp_config.content_inspect_min_size = FILEDATA_CONTENT_INSPECT_MIN_SIZE;
ConfNode *t = ConfGetNode("app-layer.protocols.smtp.inspected-tracker");
ConfNode *p = NULL;
if (t != NULL) {
TAILQ_FOREACH(p, &t->head, next) {
if (strcasecmp("content-limit", p->name) == 0) {
if (ParseSizeStringU32(p->val, &content_limit) < 0) {
SCLogWarning("parsing content-limit %s failed", p->val);
content_limit = FILEDATA_CONTENT_LIMIT;
}
smtp_config.content_limit = content_limit;
}
if (strcasecmp("content-inspect-min-size", p->name) == 0) {
if (ParseSizeStringU32(p->val, &content_inspect_min_size) < 0) {
SCLogWarning("parsing content-inspect-min-size %s failed", p->val);
content_inspect_min_size = FILEDATA_CONTENT_INSPECT_MIN_SIZE;
}
smtp_config.content_inspect_min_size = content_inspect_min_size;
}
if (strcasecmp("content-inspect-window", p->name) == 0) {
if (ParseSizeStringU32(p->val, &content_inspect_window) < 0) {
SCLogWarning("parsing content-inspect-window %s failed", p->val);
content_inspect_window = FILEDATA_CONTENT_INSPECT_WINDOW;
}
smtp_config.content_inspect_window = content_inspect_window;
}
}
}
smtp_config.sbcfg.buf_size = content_limit ? content_limit : 256;
if (ConfGetBool("app-layer.protocols.smtp.raw-extraction",
(int *)&smtp_config.raw_extraction) != 1) {
smtp_config.raw_extraction = SMTP_RAW_EXTRACTION_DEFAULT_VALUE;
}
if (smtp_config.raw_extraction && smtp_config.decode_mime) {
SCLogError("\"decode-mime\" and \"raw-extraction\" "
"options can't be enabled at the same time, "
"disabling raw extraction");
smtp_config.raw_extraction = 0;
}
SCReturn;
}
static void SMTPSetEvent(SMTPState *s, uint8_t e)
{
SCLogDebug("setting event %u", e);
if (s->curr_tx != NULL) {
AppLayerDecoderEventsSetEventRaw(&s->curr_tx->tx_data.events, e);
// s->events++;
return;
}
SCLogDebug("couldn't set event %u", e);
}
static SMTPTransaction *SMTPTransactionCreate(void)
{
SMTPTransaction *tx = SCCalloc(1, sizeof(*tx));
if (tx == NULL) {
return NULL;
}
TAILQ_INIT(&tx->rcpt_to_list);
tx->mime_state = NULL;
tx->tx_data.file_tx = STREAM_TOSERVER; // can xfer files
return tx;
}
static void FlagDetectStateNewFile(SMTPTransaction *tx)
{
if (tx && tx->tx_data.de_state) {
SCLogDebug("DETECT_ENGINE_STATE_FLAG_FILE_NEW set");
tx->tx_data.de_state->dir_state[0].flags |= DETECT_ENGINE_STATE_FLAG_FILE_NEW;
} else if (tx == NULL) {
SCLogDebug("DETECT_ENGINE_STATE_FLAG_FILE_NEW NOT set, no TX");
} else if (tx->tx_data.de_state == NULL) {
SCLogDebug("DETECT_ENGINE_STATE_FLAG_FILE_NEW NOT set, no TX DESTATE");
}
}
static void SMTPNewFile(SMTPTransaction *tx, File *file)
{
DEBUG_VALIDATE_BUG_ON(tx == NULL);
DEBUG_VALIDATE_BUG_ON(file == NULL);
#ifdef UNITTESTS
if (RunmodeIsUnittests()) {
if (tx == NULL || file == NULL) {
return;
}
}
#endif
FlagDetectStateNewFile(tx);
tx->tx_data.files_opened++;
/* set inspect sizes used in file pruning logic.
* TODO consider moving this to the file.data code that
* would actually have use for this. */
FileSetInspectSizes(file, smtp_config.content_inspect_window,
smtp_config.content_inspect_min_size);
}
int SMTPProcessDataChunk(const uint8_t *chunk, uint32_t len,
MimeDecParseState *state)
{
SCEnter();
int ret = MIME_DEC_OK;
Flow *flow = (Flow *) state->data;
SMTPState *smtp_state = (SMTPState *) flow->alstate;
SMTPTransaction *tx = smtp_state->curr_tx;
MimeDecEntity *entity = (MimeDecEntity *) state->stack->top->data;
FileContainer *files = NULL;
DEBUG_VALIDATE_BUG_ON(tx == NULL);
uint16_t flags = FileFlowToFlags(flow, STREAM_TOSERVER);
/* we depend on detection engine for file pruning */
flags |= FILE_USE_DETECT;
/* Find file */
if (entity->ctnt_flags & CTNT_IS_ATTACHMENT) {
files = &tx->files_ts;
/* Open file if necessary */
if (state->body_begin) {
if (SCLogDebugEnabled()) {
SCLogDebug("Opening file...%u bytes", len);
printf("File - ");
for (uint32_t i = 0; i < entity->filename_len; i++) {
printf("%c", entity->filename[i]);
}
printf("\n");
}
/* Set storage flag if applicable since only the first file in the
* flow seems to be processed by the 'filestore' detector */
if (files->head != NULL && (files->head->flags & FILE_STORE)) {
flags |= FILE_STORE;
}
uint32_t depth = smtp_config.content_inspect_min_size +
(smtp_state->toserver_data_count - smtp_state->toserver_last_data_stamp);
SCLogDebug("StreamTcpReassemblySetMinInspectDepth STREAM_TOSERVER %"PRIu32, depth);
StreamTcpReassemblySetMinInspectDepth(flow->protoctx, STREAM_TOSERVER, depth);
uint16_t flen = (uint16_t)entity->filename_len;
if (entity->filename_len > SC_FILENAME_MAX) {
flen = SC_FILENAME_MAX;
SMTPSetEvent(smtp_state, SMTP_DECODER_EVENT_MIME_LONG_FILENAME);
}
if (FileOpenFileWithId(files, &smtp_config.sbcfg, smtp_state->file_track_id++,
(uint8_t *)entity->filename, flen, (uint8_t *)chunk, len, flags) != 0) {
ret = MIME_DEC_ERR_DATA;
SCLogDebug("FileOpenFile() failed");
} else {
SMTPNewFile(tx, files->tail);
}
/* If close in the same chunk, then pass in empty bytes */
if (state->body_end) {
SCLogDebug("Closing file...%u bytes", len);
if (files->tail->state == FILE_STATE_OPENED) {
ret = FileCloseFile(files, &smtp_config.sbcfg, (uint8_t *)NULL, 0, flags);
if (ret != 0) {
SCLogDebug("FileCloseFile() failed: %d", ret);
ret = MIME_DEC_ERR_DATA;
}
} else {
SCLogDebug("File already closed");
}
depth = smtp_state->toserver_data_count - smtp_state->toserver_last_data_stamp;
AppLayerParserTriggerRawStreamReassembly(flow, STREAM_TOSERVER);
SCLogDebug("StreamTcpReassemblySetMinInspectDepth STREAM_TOSERVER %u",
depth);
StreamTcpReassemblySetMinInspectDepth(flow->protoctx, STREAM_TOSERVER,
depth);
}
} else if (state->body_end) {
/* Close file */
SCLogDebug("Closing file...%u bytes", len);
if (files->tail && files->tail->state == FILE_STATE_OPENED) {
ret = FileCloseFile(files, &smtp_config.sbcfg, (uint8_t *)chunk, len, flags);
if (ret != 0) {
SCLogDebug("FileCloseFile() failed: %d", ret);
ret = MIME_DEC_ERR_DATA;
}
} else {
SCLogDebug("File already closed");
}
uint32_t depth = smtp_state->toserver_data_count - smtp_state->toserver_last_data_stamp;
AppLayerParserTriggerRawStreamReassembly(flow, STREAM_TOSERVER);
SCLogDebug("StreamTcpReassemblySetMinInspectDepth STREAM_TOSERVER %u",
depth);
StreamTcpReassemblySetMinInspectDepth(flow->protoctx,
STREAM_TOSERVER, depth);
} else {
/* Append data chunk to file */
SCLogDebug("Appending file...%u bytes", len);
/* 0 is ok, -2 is not stored, -1 is error */
ret = FileAppendData(files, &smtp_config.sbcfg, (uint8_t *)chunk, len);
if (ret == -2) {
ret = 0;
SCLogDebug("FileAppendData() - file no longer being extracted");
} else if (ret < 0) {
SCLogDebug("FileAppendData() failed: %d", ret);
ret = MIME_DEC_ERR_DATA;
}
if (files->tail && files->tail->content_inspected == 0 &&
files->tail->size >= smtp_config.content_inspect_min_size) {
uint32_t depth = smtp_config.content_inspect_min_size +
(smtp_state->toserver_data_count - smtp_state->toserver_last_data_stamp);
AppLayerParserTriggerRawStreamReassembly(flow, STREAM_TOSERVER);
SCLogDebug("StreamTcpReassemblySetMinInspectDepth STREAM_TOSERVER %u",
depth);
StreamTcpReassemblySetMinInspectDepth(flow->protoctx,
STREAM_TOSERVER, depth);
/* after the start of the body inspection, disable the depth logic */
} else if (files->tail && files->tail->content_inspected > 0) {
StreamTcpReassemblySetMinInspectDepth(flow->protoctx,
STREAM_TOSERVER, 0);
/* expand the limit as long as we get file data, as the file data is bigger on the
* wire due to base64 */
} else {
uint32_t depth = smtp_config.content_inspect_min_size +
(smtp_state->toserver_data_count - smtp_state->toserver_last_data_stamp);
SCLogDebug("StreamTcpReassemblySetMinInspectDepth STREAM_TOSERVER %"PRIu32,
depth);
StreamTcpReassemblySetMinInspectDepth(flow->protoctx,
STREAM_TOSERVER, depth);
}
}
if (ret == 0) {
SCLogDebug("Successfully processed file data!");
}
} else {
SCLogDebug("Body not a Ctnt_attachment");
}
SCReturnInt(ret);
}
/**
* \internal
* \brief Get the next line from input. It doesn't do any length validation.
*
* \param state The smtp state.
*
* \retval 0 On success.
* \retval -1 Either when we don't have any new lines to supply anymore or
* on failure.
*/
static AppLayerResult SMTPGetLine(SMTPState *state, SMTPInput *input, SMTPLine *line)
{
SCEnter();
/* we have run out of input */
if (input->len <= 0)
return APP_LAYER_ERROR;
uint8_t *lf_idx = memchr(input->buf + input->consumed, 0x0a, input->len);
if (lf_idx == NULL) {
if (!state->discard_till_lf && input->len >= SMTP_LINE_BUFFER_LIMIT) {
line->buf = input->buf;
line->len = SMTP_LINE_BUFFER_LIMIT;
line->delim_len = 0;
SCReturnStruct(APP_LAYER_OK);
}
SCReturnStruct(APP_LAYER_INCOMPLETE(input->consumed, input->len + 1));
} else {
uint32_t o_consumed = input->consumed;
input->consumed = lf_idx - input->buf + 1;
line->len = input->consumed - o_consumed;
input->len -= line->len;
DEBUG_VALIDATE_BUG_ON((input->consumed + input->len) != input->orig_len);
if (state->discard_till_lf) {
// Whatever came in with first LF should also get discarded
state->discard_till_lf = false;
line->len = 0;
line->delim_len = 0;
SCReturnStruct(APP_LAYER_OK);
}
line->buf = input->buf + o_consumed;
if (input->consumed >= 2 && input->buf[input->consumed - 2] == 0x0D) {
line->delim_len = 2;
line->len -= 2;
} else {
line->delim_len = 1;
line->len -= 1;
}
SCReturnStruct(APP_LAYER_OK);
}
}
static int SMTPInsertCommandIntoCommandBuffer(uint8_t command, SMTPState *state, Flow *f)
{
SCEnter();
void *ptmp;
if (state->cmds_cnt >= state->cmds_buffer_len) {
int increment = SMTP_COMMAND_BUFFER_STEPS;
if ((int)(state->cmds_buffer_len + SMTP_COMMAND_BUFFER_STEPS) > (int)USHRT_MAX) {
increment = USHRT_MAX - state->cmds_buffer_len;
}
ptmp = SCRealloc(state->cmds,
sizeof(uint8_t) * (state->cmds_buffer_len + increment));
if (ptmp == NULL) {
SCFree(state->cmds);
state->cmds = NULL;
SCLogDebug("SCRealloc failure");
return -1;
}
state->cmds = ptmp;
state->cmds_buffer_len += increment;
}
if (state->cmds_cnt >= 1 &&
((state->cmds[state->cmds_cnt - 1] == SMTP_COMMAND_STARTTLS) ||
(state->cmds[state->cmds_cnt - 1] == SMTP_COMMAND_DATA))) {
/* decoder event */
SMTPSetEvent(state, SMTP_DECODER_EVENT_INVALID_PIPELINED_SEQUENCE);
/* we have to have EHLO, DATA, VRFY, EXPN, TURN, QUIT, NOOP,
* STARTTLS as the last command in pipelined mode */
}
/** \todo decoder event */
if ((int)(state->cmds_cnt + 1) > (int)USHRT_MAX) {
SCLogDebug("command buffer overflow");
return -1;
}
state->cmds[state->cmds_cnt] = command;
state->cmds_cnt++;
return 0;
}
static int SMTPProcessCommandBDAT(
SMTPState *state, Flow *f, AppLayerParserState *pstate, const SMTPLine *line)
{
SCEnter();
state->bdat_chunk_idx += (line->len + line->delim_len);
if (state->bdat_chunk_idx > state->bdat_chunk_len) {
state->parser_state &= ~SMTP_PARSER_STATE_COMMAND_DATA_MODE;
/* decoder event */
SMTPSetEvent(state, SMTP_DECODER_EVENT_BDAT_CHUNK_LEN_EXCEEDED);
SCReturnInt(-1);
} else if (state->bdat_chunk_idx == state->bdat_chunk_len) {
state->parser_state &= ~SMTP_PARSER_STATE_COMMAND_DATA_MODE;
}
SCReturnInt(0);
}
static void SetMimeEvents(SMTPState *state)
{
if (state->curr_tx->mime_state->msg == NULL) {
return;
}
/* Generate decoder events */
MimeDecEntity *msg = state->curr_tx->mime_state->msg;
if (msg->anomaly_flags & ANOM_INVALID_BASE64) {
SMTPSetEvent(state, SMTP_DECODER_EVENT_MIME_INVALID_BASE64);
}
if (msg->anomaly_flags & ANOM_INVALID_QP) {
SMTPSetEvent(state, SMTP_DECODER_EVENT_MIME_INVALID_QP);
}
if (msg->anomaly_flags & ANOM_LONG_LINE) {
SMTPSetEvent(state, SMTP_DECODER_EVENT_MIME_LONG_LINE);
}
if (msg->anomaly_flags & ANOM_LONG_ENC_LINE) {
SMTPSetEvent(state, SMTP_DECODER_EVENT_MIME_LONG_ENC_LINE);
}
if (msg->anomaly_flags & ANOM_LONG_HEADER_NAME) {
SMTPSetEvent(state, SMTP_DECODER_EVENT_MIME_LONG_HEADER_NAME);
}
if (msg->anomaly_flags & ANOM_LONG_HEADER_VALUE) {
SMTPSetEvent(state, SMTP_DECODER_EVENT_MIME_LONG_HEADER_VALUE);
}
if (msg->anomaly_flags & ANOM_MALFORMED_MSG) {
SMTPSetEvent(state, SMTP_DECODER_EVENT_MIME_MALFORMED_MSG);
}
if (msg->anomaly_flags & ANOM_LONG_BOUNDARY) {
SMTPSetEvent(state, SMTP_DECODER_EVENT_MIME_BOUNDARY_TOO_LONG);
}
if (msg->anomaly_flags & ANOM_LONG_FILENAME) {
SMTPSetEvent(state, SMTP_DECODER_EVENT_MIME_LONG_FILENAME);
}
}
static inline void SMTPTransactionComplete(SMTPState *state)
{
DEBUG_VALIDATE_BUG_ON(state->curr_tx == NULL);
if (state->curr_tx)
state->curr_tx->done = 1;
}
/**
* \retval 0 ok
* \retval -1 error
*/
static int SMTPProcessCommandDATA(SMTPState *state, SMTPTransaction *tx, Flow *f,
AppLayerParserState *pstate, const SMTPLine *line)
{
SCEnter();
DEBUG_VALIDATE_BUG_ON(tx == NULL);
if (!(state->parser_state & SMTP_PARSER_STATE_COMMAND_DATA_MODE)) {
/* looks like are still waiting for a confirmation from the server */
return 0;
}
if (line->len == 1 && line->buf[0] == '.') {
state->parser_state &= ~SMTP_PARSER_STATE_COMMAND_DATA_MODE;
/* kinda like a hack. The mail sent in DATA mode, would be
* acknowledged with a reply. We insert a dummy command to
* the command buffer to be used by the reply handler to match
* the reply received */
SMTPInsertCommandIntoCommandBuffer(SMTP_COMMAND_DATA_MODE, state, f);
if (smtp_config.raw_extraction) {
/* we use this as the signal that message data is complete. */
FileCloseFile(&tx->files_ts, &smtp_config.sbcfg, NULL, 0, 0);
} else if (smtp_config.decode_mime && tx->mime_state != NULL) {
/* Complete parsing task */
int ret = MimeDecParseComplete(tx->mime_state);
if (ret != MIME_DEC_OK) {
SMTPSetEvent(state, SMTP_DECODER_EVENT_MIME_PARSE_FAILED);
SCLogDebug("MimeDecParseComplete() function failed");
}
/* Generate decoder events */
SetMimeEvents(state);
}
SMTPTransactionComplete(state);
SCLogDebug("marked tx as done");
} else if (smtp_config.raw_extraction) {
// message not over, store the line. This is a substitution of
// ProcessDataChunk
FileAppendData(&tx->files_ts, &smtp_config.sbcfg, line->buf, line->len + line->delim_len);
}
/* If DATA, then parse out a MIME message */
if (state->current_command == SMTP_COMMAND_DATA &&
(state->parser_state & SMTP_PARSER_STATE_COMMAND_DATA_MODE)) {
if (smtp_config.decode_mime && tx->mime_state != NULL) {
int ret = MimeDecParseLine(line->buf, line->len, line->delim_len, tx->mime_state);
if (ret != MIME_DEC_OK) {
if (ret != MIME_DEC_ERR_STATE) {
/* Generate decoder events */
SetMimeEvents(state);
SCLogDebug("MimeDecParseLine() function returned an error code: %d", ret);
SMTPSetEvent(state, SMTP_DECODER_EVENT_MIME_PARSE_FAILED);
}
/* keep the parser in its error state so we can log that,
* the parser will reject new data */
}
}
}
return 0;
}
static int SMTPProcessCommandSTARTTLS(SMTPState *state, Flow *f,
AppLayerParserState *pstate)
{
return 0;
}
static inline bool IsReplyToCommand(const SMTPState *state, const uint8_t cmd)
{
return (state->cmds_idx < state->cmds_buffer_len &&
state->cmds[state->cmds_idx] == cmd);
}
static int SMTPProcessReply(SMTPState *state, Flow *f, AppLayerParserState *pstate,
SMTPThreadCtx *td, SMTPInput *input, const SMTPLine *line)
{
SCEnter();
/* Line with just LF */
if (line->len == 0 && input->consumed == 1 && line->delim_len == 1) {
return 0; // to continue processing further
}
/* the reply code has to contain at least 3 bytes, to hold the 3 digit
* reply code */
if (line->len < 3) {
/* decoder event */
SMTPSetEvent(state, SMTP_DECODER_EVENT_INVALID_REPLY);
return -1;
}
if (line->len >= 4) {
if (state->parser_state & SMTP_PARSER_STATE_PARSING_MULTILINE_REPLY) {
if (line->buf[3] != '-') {
state->parser_state &= ~SMTP_PARSER_STATE_PARSING_MULTILINE_REPLY;
}
} else {
if (line->buf[3] == '-') {
state->parser_state |= SMTP_PARSER_STATE_PARSING_MULTILINE_REPLY;
}
}
} else {
if (state->parser_state & SMTP_PARSER_STATE_PARSING_MULTILINE_REPLY) {
state->parser_state &= ~SMTP_PARSER_STATE_PARSING_MULTILINE_REPLY;
}
}
/* I don't like this pmq reset here. We'll devise a method later, that
* should make the use of the mpm very efficient */
PmqReset(td->pmq);
int mpm_cnt = mpm_table[SMTP_MPM].Search(
smtp_mpm_ctx, td->smtp_mpm_thread_ctx, td->pmq, line->buf, 3);
if (mpm_cnt == 0) {
/* set decoder event - reply code invalid */
SMTPSetEvent(state, SMTP_DECODER_EVENT_INVALID_REPLY);
SCLogDebug("invalid reply code %02x %02x %02x", line->buf[0], line->buf[1], line->buf[2]);
SCReturnInt(-1);
}
enum SMTPCode reply_code = smtp_reply_map[td->pmq->rule_id_array[0]].enum_value;
SCLogDebug("REPLY: reply_code %u / %s", reply_code,
smtp_reply_map[reply_code].enum_name);
if (state->cmds_idx == state->cmds_cnt) {
if (!(state->parser_state & SMTP_PARSER_STATE_FIRST_REPLY_SEEN)) {
/* the first server reply can be a multiline message. Let's
* flag the fact that we have seen the first reply only at the end
* of a multiline reply
*/
if (!(state->parser_state & SMTP_PARSER_STATE_PARSING_MULTILINE_REPLY))
state->parser_state |= SMTP_PARSER_STATE_FIRST_REPLY_SEEN;
if (reply_code == SMTP_REPLY_220)
SCReturnInt(0);
else {
SMTPSetEvent(state, SMTP_DECODER_EVENT_INVALID_REPLY);
SCReturnInt(0);
}
} else {
/* decoder event - unable to match reply with request */
SCLogDebug("unable to match reply with request");
SCReturnInt(0);
}
}
if (state->cmds_cnt == 0) {
/* reply but not a command we have stored, fall through */
} else if (IsReplyToCommand(state, SMTP_COMMAND_STARTTLS)) {
if (reply_code == SMTP_REPLY_220) {
/* we are entering STARRTTLS data mode */
state->parser_state |= SMTP_PARSER_STATE_COMMAND_DATA_MODE;
if (!AppLayerRequestProtocolTLSUpgrade(f)) {
SMTPSetEvent(state, SMTP_DECODER_EVENT_FAILED_PROTOCOL_CHANGE);
}
if (state->curr_tx) {
SMTPTransactionComplete(state);
}
} else {
/* decoder event */
SMTPSetEvent(state, SMTP_DECODER_EVENT_TLS_REJECTED);
}
} else if (IsReplyToCommand(state, SMTP_COMMAND_DATA)) {
if (reply_code == SMTP_REPLY_354) {
/* Next comes the mail for the DATA command in toserver direction */
state->parser_state |= SMTP_PARSER_STATE_COMMAND_DATA_MODE;
} else {
/* decoder event */
SMTPSetEvent(state, SMTP_DECODER_EVENT_DATA_COMMAND_REJECTED);
}
} else if (IsReplyToCommand(state, SMTP_COMMAND_RSET)) {
if (reply_code == SMTP_REPLY_250 && state->curr_tx &&
!(state->parser_state & SMTP_PARSER_STATE_PARSING_MULTILINE_REPLY)) {
SMTPTransactionComplete(state);
}
} else {
/* we don't care for any other command for now */
}
/* if it is a multi-line reply, we need to move the index only once for all
* the line of the reply. We unset the multiline flag on the last
* line of the multiline reply, following which we increment the index */
if (!(state->parser_state & SMTP_PARSER_STATE_PARSING_MULTILINE_REPLY)) {
state->cmds_idx++;
} else if (state->parser_state & SMTP_PARSER_STATE_FIRST_REPLY_SEEN) {
/* we check if the server is indicating pipelining support */
if (reply_code == SMTP_REPLY_250 && line->len == 14 &&
SCMemcmpLowercase("pipelining", line->buf + 4, 10) == 0) {
state->parser_state |= SMTP_PARSER_STATE_PIPELINING_SERVER;
}
}
/* if we have matched all the buffered commands, reset the cnt and index */
if (state->cmds_idx == state->cmds_cnt) {
state->cmds_cnt = 0;
state->cmds_idx = 0;
}
return 0;
}
static int SMTPParseCommandBDAT(SMTPState *state, const SMTPLine *line)
{
SCEnter();
int i = 4;
while (i < line->len) {
if (line->buf[i] != ' ') {
break;
}
i++;
}
if (i == 4) {
/* decoder event */
return -1;
}
if (i == line->len) {