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osmo-pcap
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server: Improve verification of messages from client 

Take the chance to define SERVER_MAX_DATA_SIZE as pcap payload, which we
can later match to configurable snaplen parameter.

Change-Id: I45d4c59026faf1108c0976eb6ad8c270e3577dbf
This commit is contained in:
Pau Espin 2018-10-08 18:42:05 +02:00
parent b799344ecd
commit 868a501213
2 changed files with 38 additions and 8 deletions
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2
include/osmo-pcap/osmo_pcap_server.h
View File

@ -91,7 +91,7 @@ struct osmo_pcap_conn {
int state;
int pend;
int reopen;
char buf[SERVER_MAX_DATA_SIZE + sizeof(struct osmo_pcap_data)];
char buf[sizeof(struct osmo_pcap_data) + sizeof(struct osmo_pcap_pkthdr) + SERVER_MAX_DATA_SIZE];
struct osmo_pcap_data *data;
/* statistics */

44
src/osmo_server_network.c
View File

@ -192,12 +192,15 @@ static int link_data(struct osmo_pcap_conn *conn, struct osmo_pcap_data *data)
{
struct pcap_file_header *hdr;
if (data->len != sizeof(*hdr)) {
LOGP(DSERVER, LOGL_ERROR, "The pcap_file_header does not fit.\n");
hdr = (struct pcap_file_header *) &data->data[0];
if (hdr->snaplen > SERVER_MAX_DATA_SIZE) {
LOGP(DSERVER, LOGL_ERROR,
"The recvd pcap_file_header contains too big snaplen %zu > %zu\n",
(size_t) hdr->snaplen, (size_t) SERVER_MAX_DATA_SIZE);
return -1;
}
hdr = (struct pcap_file_header *) &data->data[0];
if (!conn->no_store && conn->local_fd < 0) {
conn->file_hdr = *hdr;
restart_pcap(conn);
@ -335,6 +338,36 @@ static int do_read(struct osmo_pcap_conn *conn, void *buf, size_t size)
return do_read_tls(conn, buf, size);
}
static bool pcap_data_valid(struct osmo_pcap_conn *conn)
{
unsigned int min_len, max_len;
switch ((enum OsmoPcapDataType) conn->data->type) {
case PKT_LINK_HDR:
if (conn->data->len != sizeof(struct pcap_file_header)) {
LOGP(DSERVER, LOGL_ERROR,
"Implausible llink_hdr length: %u != %zu\n",
conn->data->len, sizeof(struct osmo_pcap_pkthdr));
return false;
}
break;
case PKT_LINK_DATA:
min_len = sizeof(struct osmo_pcap_pkthdr);
max_len = SERVER_MAX_DATA_SIZE + sizeof(struct osmo_pcap_pkthdr);
if (conn->data->len < min_len || conn->data->len > max_len) {
LOGP(DSERVER, LOGL_ERROR,
"Implausible data length: %u < %u <= %u\n",
min_len, conn->data->len, max_len);
return false;
}
break;
default:
LOGP(DSERVER, LOGL_ERROR, "Unknown data type %" PRIx8 "\n",
conn->data->type);
return false;
}
return true;
}
static int read_cb_initial(struct osmo_pcap_conn *conn)
{
int rc;
@ -354,11 +387,8 @@ static int read_cb_initial(struct osmo_pcap_conn *conn)
} else if (conn->pend == 0) {
conn->data->len = ntohs(conn->data->len);
if (conn->data->len > SERVER_MAX_DATA_SIZE) {
LOGP(DSERVER, LOGL_ERROR,
"Implausible data length: %u\n", conn->data->len);
if (!pcap_data_valid(conn))
return -1;
}
conn->state = STATE_DATA;
conn->pend = conn->data->len;