diff options
| -rw-r--r-- | networking/udhcp/common.c | 19 | ||||
| -rw-r--r-- | networking/udhcp/common.h | 4 | ||||
| -rw-r--r-- | networking/udhcp/dhcpc.c | 6 | ||||
| -rw-r--r-- | networking/udhcp/dhcpd.c | 6 |
4 files changed, 29 insertions, 6 deletions
diff --git a/networking/udhcp/common.c b/networking/udhcp/common.c index e5fd74f..41b05b8 100644 --- a/networking/udhcp/common.c +++ b/networking/udhcp/common.c @@ -272,6 +272,15 @@ uint8_t* FAST_FUNC udhcp_get_option(struct dhcp_packet *packet, int code) goto complain; /* complain and return NULL */ if (optionptr[OPT_CODE] == code) { + if (optionptr[OPT_LEN] == 0) { + /* So far no valid option with length 0 known. + * Having this check means that searching + * for DHCP_MESSAGE_TYPE need not worry + * that returned pointer might be unsafe + * to dereference. + */ + goto complain; /* complain and return NULL */ + } log_option("option found", optionptr); return optionptr + OPT_DATA; } @@ -289,6 +298,16 @@ uint8_t* FAST_FUNC udhcp_get_option(struct dhcp_packet *packet, int code) return NULL; } +uint8_t* FAST_FUNC udhcp_get_option32(struct dhcp_packet *packet, int code) +{ + uint8_t *r = udhcp_get_option(packet, code); + if (r) { + if (r[-1] != 4) + r = NULL; + } + return r; +} + /* Return the position of the 'end' option (no bounds checking) */ int FAST_FUNC udhcp_end_option(uint8_t *optionptr) { diff --git a/networking/udhcp/common.h b/networking/udhcp/common.h index 7ad603d..9511152 100644 --- a/networking/udhcp/common.h +++ b/networking/udhcp/common.h @@ -205,6 +205,10 @@ extern const uint8_t dhcp_option_lengths[] ALIGN1; unsigned FAST_FUNC udhcp_option_idx(const char *name, const char *option_strings); uint8_t *udhcp_get_option(struct dhcp_packet *packet, int code) FAST_FUNC; +/* Same as above + ensures that option length is 4 bytes + * (returns NULL if size is different) + */ +uint8_t *udhcp_get_option32(struct dhcp_packet *packet, int code) FAST_FUNC; int udhcp_end_option(uint8_t *optionptr) FAST_FUNC; void udhcp_add_binary_option(struct dhcp_packet *packet, uint8_t *addopt) FAST_FUNC; #if ENABLE_UDHCPC || ENABLE_UDHCPD diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c index 4b23e4d..5b3fd53 100644 --- a/networking/udhcp/dhcpc.c +++ b/networking/udhcp/dhcpc.c @@ -1691,7 +1691,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv) * They say ISC DHCP client supports this case. */ server_addr = 0; - temp = udhcp_get_option(&packet, DHCP_SERVER_ID); + temp = udhcp_get_option32(&packet, DHCP_SERVER_ID); if (!temp) { bb_error_msg("no server ID, using 0.0.0.0"); } else { @@ -1718,7 +1718,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv) struct in_addr temp_addr; uint8_t *temp; - temp = udhcp_get_option(&packet, DHCP_LEASE_TIME); + temp = udhcp_get_option32(&packet, DHCP_LEASE_TIME); if (!temp) { bb_error_msg("no lease time with ACK, using 1 hour lease"); lease_seconds = 60 * 60; @@ -1813,7 +1813,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv) uint32_t svid; uint8_t *temp; - temp = udhcp_get_option(&packet, DHCP_SERVER_ID); + temp = udhcp_get_option32(&packet, DHCP_SERVER_ID); if (!temp) { non_matching_svid: log1("received DHCP NAK with wrong" diff --git a/networking/udhcp/dhcpd.c b/networking/udhcp/dhcpd.c index a8cd3f0..477856d 100644 --- a/networking/udhcp/dhcpd.c +++ b/networking/udhcp/dhcpd.c @@ -640,7 +640,7 @@ static void add_server_options(struct dhcp_packet *packet) static uint32_t select_lease_time(struct dhcp_packet *packet) { uint32_t lease_time_sec = server_config.max_lease_sec; - uint8_t *lease_time_opt = udhcp_get_option(packet, DHCP_LEASE_TIME); + uint8_t *lease_time_opt = udhcp_get_option32(packet, DHCP_LEASE_TIME); if (lease_time_opt) { move_from_unaligned32(lease_time_sec, lease_time_opt); lease_time_sec = ntohl(lease_time_sec); @@ -987,7 +987,7 @@ int udhcpd_main(int argc UNUSED_PARAM, char **argv) } /* Get SERVER_ID if present */ - server_id_opt = udhcp_get_option(&packet, DHCP_SERVER_ID); + server_id_opt = udhcp_get_option32(&packet, DHCP_SERVER_ID); if (server_id_opt) { uint32_t server_id_network_order; move_from_unaligned32(server_id_network_order, server_id_opt); @@ -1011,7 +1011,7 @@ int udhcpd_main(int argc UNUSED_PARAM, char **argv) } /* Get REQUESTED_IP if present */ - requested_ip_opt = udhcp_get_option(&packet, DHCP_REQUESTED_IP); + requested_ip_opt = udhcp_get_option32(&packet, DHCP_REQUESTED_IP); if (requested_ip_opt) { move_from_unaligned32(requested_nip, requested_ip_opt); } |