| --- busybox-1.19.4/networking/udhcp/common.c |
| +++ busybox-1.19.4-udhcp/networking/udhcp/common.c |
| @@ -29,16 +29,16 @@ 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 */ |
| { OPTION_U16 , 0x1a }, /* DHCP_MTU */ |
| { 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 */ |
| @@ -46,7 +46,7 @@ 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 */ |
| @@ -143,6 +143,7 @@ const uint8_t dhcp_option_lengths[] ALIG |
| [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, |
| @@ -411,7 +412,9 @@ 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++; |
| @@ -475,6 +478,7 @@ int FAST_FUNC udhcp_str2optset(const cha |
| retval = udhcp_str2nip(val, buffer + 4); |
| break; |
| case OPTION_STRING: |
| + case OPTION_STRING_HOST: |
| #if ENABLE_FEATURE_UDHCP_RFC3397 |
| case OPTION_DNS_STRING: |
| #endif |
| --- busybox-1.19.4/networking/udhcp/common.h |
| +++ busybox-1.19.4-udhcp/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, |
| --- busybox-1.19.4/networking/udhcp/dhcpc.c |
| +++ busybox-1.19.4-udhcp/networking/udhcp/dhcpc.c |
| @@ -101,6 +101,7 @@ static const uint8_t len_of_option_as_st |
| [OPTION_IP_PAIR ] = sizeof("255.255.255.255 ") * 2, |
| [OPTION_STATIC_ROUTES ] = sizeof("255.255.255.255/32 255.255.255.255 "), |
| [OPTION_STRING ] = 1, |
| + [OPTION_STRING_HOST ] = 1, |
| #if ENABLE_FEATURE_UDHCP_RFC3397 |
| [OPTION_DNS_STRING ] = 1, /* unused */ |
| /* Hmmm, this severely overestimates size if SIP_SERVERS option |
| @@ -135,6 +136,63 @@ 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) |
| { |
| @@ -185,8 +243,11 @@ static NOINLINE char *xmalloc_optname_op |
| break; |
| } |
| 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; /* Short circuit this case */ |
| case OPTION_STATIC_ROUTES: { |
| /* Option binary format: |
| @@ -314,6 +375,7 @@ static char **fill_envp(struct dhcp_pack |
| /* +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) { |