diff options
| -rw-r--r-- | networking/udhcp/common.c | 14 | ||||
| -rw-r--r-- | networking/udhcp/common.h | 3 | ||||
| -rw-r--r-- | networking/udhcp/dhcpc.c | 61 |
3 files changed, 73 insertions, 5 deletions
diff --git a/networking/udhcp/common.c b/networking/udhcp/common.c index a89dce3..cf6b1ca 100644 --- a/networking/udhcp/common.c +++ b/networking/udhcp/common.c @@ -29,9 +29,9 @@ const struct dhcp_optflag dhcp_optflags[] = { // { OPTION_IP | OPTION_LIST , 0x07 }, /* DHCP_LOG_SERVER */ // { OPTION_IP | OPTION_LIST , 0x08 }, /* DHCP_COOKIE_SERVER */ { OPTION_IP | OPTION_LIST , 0x09 }, /* DHCP_LPR_SERVER */ - { OPTION_STRING | OPTION_REQ, 0x0c }, /* DHCP_HOST_NAME */ + { OPTION_STRING_HOST | OPTION_REQ, 0x0c }, /* DHCP_HOST_NAME */ { OPTION_U16 , 0x0d }, /* DHCP_BOOT_SIZE */ - { OPTION_STRING | OPTION_REQ, 0x0f }, /* DHCP_DOMAIN_NAME */ + { OPTION_STRING_HOST | OPTION_REQ, 0x0f }, /* DHCP_DOMAIN_NAME */ { OPTION_IP , 0x10 }, /* DHCP_SWAP_SERVER */ { OPTION_STRING , 0x11 }, /* DHCP_ROOT_PATH */ { OPTION_U8 , 0x17 }, /* DHCP_IP_TTL */ @@ -41,7 +41,7 @@ const struct dhcp_optflag dhcp_optflags[] = { //server would let us know anyway? { OPTION_IP | OPTION_REQ, 0x1c }, /* DHCP_BROADCAST */ { OPTION_IP_PAIR | OPTION_LIST , 0x21 }, /* DHCP_ROUTES */ - { OPTION_STRING , 0x28 }, /* DHCP_NIS_DOMAIN */ + { OPTION_STRING_HOST , 0x28 }, /* DHCP_NIS_DOMAIN */ { OPTION_IP | OPTION_LIST , 0x29 }, /* DHCP_NIS_SERVER */ { OPTION_IP | OPTION_LIST | OPTION_REQ, 0x2a }, /* DHCP_NTP_SERVER */ { OPTION_IP | OPTION_LIST , 0x2c }, /* DHCP_WINS_SERVER */ @@ -49,7 +49,7 @@ const struct dhcp_optflag dhcp_optflags[] = { { OPTION_IP , 0x36 }, /* DHCP_SERVER_ID */ { OPTION_STRING , 0x38 }, /* DHCP_ERR_MESSAGE */ //TODO: must be combined with 'sname' and 'file' handling: - { OPTION_STRING , 0x42 }, /* DHCP_TFTP_SERVER_NAME */ + { OPTION_STRING_HOST , 0x42 }, /* DHCP_TFTP_SERVER_NAME */ { OPTION_STRING , 0x43 }, /* DHCP_BOOT_FILE */ //TODO: not a string, but a set of LASCII strings: // { OPTION_STRING , 0x4D }, /* DHCP_USER_CLASS */ @@ -148,6 +148,7 @@ const uint8_t dhcp_option_lengths[] ALIGN1 = { [OPTION_IP_PAIR] = 8, // [OPTION_BOOLEAN] = 1, [OPTION_STRING] = 1, /* ignored by udhcp_str2optset */ + [OPTION_STRING_HOST] = 1, /* ignored by udhcp_str2optset */ #if ENABLE_FEATURE_UDHCP_RFC3397 [OPTION_DNS_STRING] = 1, /* ignored by both udhcp_str2optset and xmalloc_optname_optval */ [OPTION_SIP_SERVERS] = 1, @@ -417,7 +418,9 @@ static NOINLINE void attach_option( /* actually 255 is ok too, but adding a space can overlow it */ existing->data = xrealloc(existing->data, OPT_DATA + 1 + old_len + length); - if ((optflag->flags & OPTION_TYPE_MASK) == OPTION_STRING) { + if ((optflag->flags & OPTION_TYPE_MASK) == OPTION_STRING + || (optflag->flags & OPTION_TYPE_MASK) == OPTION_STRING_HOST + ) { /* add space separator between STRING options in a list */ existing->data[OPT_DATA + old_len] = ' '; old_len++; @@ -481,6 +484,7 @@ int FAST_FUNC udhcp_str2optset(const char *const_str, void *arg) retval = udhcp_str2nip(val, buffer + 4); break; case OPTION_STRING: + case OPTION_STRING_HOST: #if ENABLE_FEATURE_UDHCP_RFC3397 case OPTION_DNS_STRING: #endif diff --git a/networking/udhcp/common.h b/networking/udhcp/common.h index 479ae49..cfd5867 100644 --- a/networking/udhcp/common.h +++ b/networking/udhcp/common.h @@ -80,6 +80,9 @@ enum { OPTION_IP = 1, OPTION_IP_PAIR, OPTION_STRING, + /* Opts of STRING_HOST type will be sanitized before they are passed + * to udhcpc script's environment: */ + OPTION_STRING_HOST, // OPTION_BOOLEAN, OPTION_U8, OPTION_U16, diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c index 945600c..2f2016c 100644 --- a/networking/udhcp/dhcpc.c +++ b/networking/udhcp/dhcpc.c @@ -135,6 +135,63 @@ static int mton(uint32_t mask) return i; } +/* Check if a given label represents a valid DNS label + * Return pointer to the first character after the label upon success, + * NULL otherwise. + * See RFC1035, 2.3.1 + */ +/* We don't need to be particularly anal. For example, allowing _, hyphen + * at the end, or leading and trailing dots would be ok, since it + * can't be used for attacks. (Leading hyphen can be, if someone uses + * cmd "$hostname" + * in the script: then hostname may be treated as an option) + */ +static const char *valid_domain_label(const char *label) +{ + unsigned char ch; + unsigned pos = 0; + + for (;;) { + ch = *label; + if ((ch|0x20) < 'a' || (ch|0x20) > 'z') { + if (pos == 0) { + /* label must begin with letter */ + return NULL; + } + if (ch < '0' || ch > '9') { + if (ch == '\0' || ch == '.') + return label; + /* DNS allows only '-', but we are more permissive */ + if (ch != '-' && ch != '_') + return NULL; + } + } + label++; + pos++; + //Do we want this? + //if (pos > 63) /* NS_MAXLABEL; labels must be 63 chars or less */ + // return NULL; + } +} + +/* Check if a given name represents a valid DNS name */ +/* See RFC1035, 2.3.1 */ +static int good_hostname(const char *name) +{ + //const char *start = name; + + for (;;) { + name = valid_domain_label(name); + if (!name) + return 0; + if (!name[0]) + return 1; + //Do we want this? + //return ((name - start) < 1025); /* NS_MAXDNAME */ + name++; + } +} + /* Create "opt_name=opt_value" string */ static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_optflag *optflag, const char *opt_name) { @@ -187,8 +244,11 @@ static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_ * the case of list of options. */ case OPTION_STRING: + case OPTION_STRING_HOST: memcpy(dest, option, len); dest[len] = '\0'; + if (type == OPTION_STRING_HOST && !good_hostname(dest)) + safe_strncpy(dest, "bad", len); return ret; case OPTION_STATIC_ROUTES: { /* Option binary format: @@ -368,6 +428,7 @@ static char **fill_envp(struct dhcp_packet *packet) /* +1 element for each option, +2 for subnet option: */ if (packet) { /* note: do not search for "pad" (0) and "end" (255) options */ +//TODO: change logic to scan packet _once_ for (i = 1; i < 255; i++) { temp = udhcp_get_option(packet, i); if (temp) { |