diff options
Diffstat (limited to 'epan/dissectors/packet-ieee80211-radiotap-iter.c')
| -rw-r--r-- | epan/dissectors/packet-ieee80211-radiotap-iter.c | 491 |
1 files changed, 491 insertions, 0 deletions
diff --git a/epan/dissectors/packet-ieee80211-radiotap-iter.c b/epan/dissectors/packet-ieee80211-radiotap-iter.c new file mode 100644 index 00000000..e7a401c8 --- /dev/null +++ b/epan/dissectors/packet-ieee80211-radiotap-iter.c @@ -0,0 +1,491 @@ +/* + * Radiotap parser + * + * Copyright 2007 Andy Green <andy@warmcat.com> + * Copyright 2009 Johannes Berg <johannes@sipsolutions.net> + * + * SPDX-License-Identifier: (ISC OR GPL-2.0-only) + */ + +#include "config.h" + +#include <errno.h> + +#include <epan/packet.h> +#include <wsutil/pint.h> + +#define le16_to_cpu GINT16_FROM_LE +#define le32_to_cpu GINT32_FROM_LE +#define get_unaligned_le16 pletoh16 +#define get_unaligned_le32 pletoh32 + +#include "packet-ieee80211-radiotap-iter.h" + +/* function prototypes and related defs are in radiotap_iter.h */ + +static const struct radiotap_align_size rtap_namespace_sizes[] = { + /* [IEEE80211_RADIOTAP_TSFT] = 0 */ { 8, 8 }, + /* [IEEE80211_RADIOTAP_FLAGS] = 1 */ { 1, 1 }, + /* [IEEE80211_RADIOTAP_RATE] = 2 */ { 1, 1 }, + /* [IEEE80211_RADIOTAP_CHANNEL] = 3 */ { 2, 4 }, + /* [IEEE80211_RADIOTAP_FHSS] = 4 */ { 2, 2 }, + /* [IEEE80211_RADIOTAP_DBM_ANTSIGNAL] = 5 */ { 1, 1 }, + /* [IEEE80211_RADIOTAP_DBM_ANTNOISE] = 6 */ { 1, 1 }, + /* [IEEE80211_RADIOTAP_LOCK_QUALITY] = 7 */ { 2, 2 }, + /* [IEEE80211_RADIOTAP_TX_ATTENUATION] = 8 */ { 2, 2 }, + /* [IEEE80211_RADIOTAP_DB_TX_ATTENUATION] = 9 */ { 2, 2 }, + /* [IEEE80211_RADIOTAP_DBM_TX_POWER] = 10 */ { 1, 1 }, + /* [IEEE80211_RADIOTAP_ANTENNA] = 11 */ { 1, 1 }, + /* [IEEE80211_RADIOTAP_DB_ANTSIGNAL] = 12 */ { 1, 1 }, + /* [IEEE80211_RADIOTAP_DB_ANTNOISE] = 13 */ { 1, 1 }, + /* [IEEE80211_RADIOTAP_RX_FLAGS] = 14 */ { 2, 2 }, + /* [IEEE80211_RADIOTAP_TX_FLAGS] = 15 */ { 2, 2 }, + /* [IEEE80211_RADIOTAP_RTS_RETRIES] = 16 */ { 1, 1 }, + /* [IEEE80211_RADIOTAP_DATA_RETRIES] = 17 */ { 1, 1 }, + /* [IEEE80211_RADIOTAP_XCHANNEL] = 18 */ { 0, 0 }, /* Unofficial, used by FreeBSD */ + /* [IEEE80211_RADIOTAP_MCS] = 19 */ { 1, 3 }, + /* [IEEE80211_RADIOTAP_AMPDU_STATUS] = 20 */ { 4, 8 }, + /* [IEEE80211_RADIOTAP_VHT] = 21 */ { 2, 12 }, + /* [IEEE80211_RADIOTAP_TIMESTAMP] = 22 */ { 8, 12 }, + /* [IEEE80211_RADIOTAP_HE] = 23 */ { 2, 12 }, + /* [IEEE80211_RADIOTAP_HE_MU] = 24 */ { 2, 12 }, + /* [IEEE80211_RADIOTAP_HE_MU_USER = 25 notdef */ { 0, 0 }, + /* [IEEE80211_RADIOTAP_0_LENGTH_PSDU = 26 */ { 1, 1 }, + /* [IEEE80211_RADIOTAP_L_SIG = 27 */ { 2, 4 }, + /* [IEEE80211_RADIOTAP_TLV = 28 */ { 4, 10 }, + /* + * add more here as they are defined in + * include/net/ieee80211_radiotap.h + */ +}; + +static const struct ieee80211_radiotap_namespace radiotap_ns = { + rtap_namespace_sizes, + (int)(sizeof(rtap_namespace_sizes) / sizeof(rtap_namespace_sizes[0])), + 0, + 0 +}; + +/* + * Sanity check. + */ +#define ITERATOR_VALID(iterator, size) \ + (((iterator)->_arg + (size) - (unsigned char *)((iterator)->_rtheader)) <= \ + (ptrdiff_t)(iterator)->_max_length) + +/** + * ieee80211_radiotap_iterator_init - radiotap parser iterator initialization + * @iterator: radiotap_iterator to initialize + * @radiotap_header: radiotap header to parse + * @max_length: total length we can parse into (eg, whole packet length) + * + * Returns: 0 or a negative error code if there is a problem. + * + * This function initializes an opaque iterator struct which can then + * be passed to ieee80211_radiotap_iterator_next() to visit every radiotap + * argument which is present in the header. It knows about extended + * present headers and handles them. + * + * How to use: + * call __ieee80211_radiotap_iterator_init() to init a semi-opaque iterator + * struct ieee80211_radiotap_iterator (no need to init the struct beforehand) + * checking for a good 0 return code. Then loop calling + * __ieee80211_radiotap_iterator_next()... it returns either 0, + * -ENOENT if there are no more args to parse, or -EINVAL if there is a problem. + * The iterator's @this_arg member points to the start of the argument + * associated with the current argument index that is present, which can be + * found in the iterator's @this_arg_index member. This arg index corresponds + * to the IEEE80211_RADIOTAP_... defines. + * + * Radiotap header length: + * You can find the CPU-endian total radiotap header length in + * iterator->max_length after executing ieee80211_radiotap_iterator_init() + * successfully. + * + * Alignment Gotcha: + * You must take care when dereferencing iterator.this_arg + * for multibyte types... the pointer is not aligned. Use + * get_unaligned((type *)iterator.this_arg) to dereference + * iterator.this_arg for type "type" safely on all arches. + * + * Example code: + * See Documentation/networking/radiotap-headers.txt + */ + +int ieee80211_radiotap_iterator_init( + struct ieee80211_radiotap_iterator *iterator, + struct ieee80211_radiotap_header *radiotap_header, + int max_length, const struct ieee80211_radiotap_vendor_namespaces *vns) +{ + /* XXX - in Wireshark, we've already checked for this */ + if (max_length < (int)sizeof(struct ieee80211_radiotap_header)) + return -EINVAL; + + /* Linux only supports version 0 radiotap format */ + /* XXX - this is Wireshark, not Linux, and we should report an expert info */ + if (radiotap_header->it_version) + return -EINVAL; + + /* sanity check for allowed length and radiotap length field */ + /* XXX - in Wireshark, this compares the length against itself. */ + if (max_length < get_unaligned_le16(&radiotap_header->it_len)) + return -EINVAL; + + iterator->_rtheader = radiotap_header; + iterator->_max_length = get_unaligned_le16(&radiotap_header->it_len); + iterator->_arg_index = 0; + iterator->_bitmap_shifter = get_unaligned_le32(&radiotap_header->it_present); + iterator->_arg = (guint8 *)radiotap_header + sizeof(*radiotap_header); + iterator->_reset_on_ext = 0; + iterator->_next_ns_data = NULL; + iterator->_next_bitmap = &radiotap_header->it_present; + iterator->_next_bitmap++; + iterator->_vns = vns; + iterator->current_namespace = &radiotap_ns; + iterator->is_radiotap_ns = 1; + iterator->tlv_mode = 0; +#ifdef RADIOTAP_SUPPORT_OVERRIDES + iterator->n_overrides = 0; + iterator->overrides = NULL; +#endif + + /* find payload start allowing for extended bitmap(s) */ + if (iterator->_bitmap_shifter & (1U << IEEE80211_RADIOTAP_EXT)) { + /* XXX - we should report an expert info here */ + if (!ITERATOR_VALID(iterator, sizeof(guint32))) + return -EINVAL; + while (get_unaligned_le32(iterator->_arg) & + (1U << IEEE80211_RADIOTAP_EXT)) { + iterator->_arg += sizeof(guint32); + + /* + * check for insanity where the present bitmaps + * keep claiming to extend up to or even beyond the + * stated radiotap header length + */ + /* XXX - we should report an expert info here */ + if (!ITERATOR_VALID(iterator, sizeof(guint32))) + return -EINVAL; + + /* XXX - we should report an expert info here */ + if ((get_unaligned_le32(iterator->_arg) & + (1U << IEEE80211_RADIOTAP_TLVS)) && + (get_unaligned_le32(iterator->_arg) & + (1U << IEEE80211_RADIOTAP_EXT))) + return -EINVAL; + } + + iterator->_arg += sizeof(guint32); + + /* + * no need to check again for blowing past stated radiotap + * header length, because ieee80211_radiotap_iterator_next + * checks it before it is dereferenced + */ + } + + iterator->this_arg = iterator->_arg; + + /* we are all initialized happily */ + + return 0; +} + +static void find_ns(struct ieee80211_radiotap_iterator *iterator, + guint32 oui, guint8 subns) +{ + int i; + + iterator->current_namespace = NULL; + + if (!iterator->_vns) + return; + + for (i = 0; i < iterator->_vns->n_ns; i++) { + if (iterator->_vns->ns[i].oui != oui) + continue; + if (iterator->_vns->ns[i].subns != subns) + continue; + + iterator->current_namespace = &iterator->_vns->ns[i]; + break; + } +} + +#ifdef RADIOTAP_SUPPORT_OVERRIDES +static int find_override(struct ieee80211_radiotap_iterator *iterator, + int *align, int *size) +{ + int i; + + if (!iterator->overrides) + return 0; + + for (i = 0; i < iterator->n_overrides; i++) { + if (iterator->_arg_index == iterator->overrides[i].field) { + *align = iterator->overrides[i].align; + *size = iterator->overrides[i].size; + if (!*align) /* erroneous override */ + return 0; + return 1; + } + } + + return 0; +} +#endif + + +/** + * ieee80211_radiotap_iterator_next - return next radiotap parser iterator arg + * @iterator: radiotap_iterator to move to next arg (if any) + * + * Returns: 0 if there is an argument to handle, + * -ENOENT if there are no more args or -EINVAL + * if there is something else wrong. + * + * This function provides the next radiotap arg index (IEEE80211_RADIOTAP_*) + * in @this_arg_index and sets @this_arg to point to the + * payload for the field. It takes care of alignment handling and extended + * present fields. @this_arg can be changed by the caller (eg, + * incremented to move inside a compound argument like + * IEEE80211_RADIOTAP_CHANNEL). The args pointed to are in + * little-endian format whatever the endianess of your CPU. + * + * Alignment Gotcha: + * You must take care when dereferencing iterator.this_arg + * for multibyte types... the pointer is not aligned. Use + * get_unaligned((type *)iterator.this_arg) to dereference + * iterator.this_arg for type "type" safely on all arches. + */ + +int ieee80211_radiotap_iterator_next( + struct ieee80211_radiotap_iterator *iterator) +{ + if (iterator->tlv_mode) { + struct ieee80211_radiotap_tlv *tlv; + guint32 size; + +#define TLV_LEN_ALIGN(x) ((x + 3) & ~3) + size = sizeof(*tlv) + TLV_LEN_ALIGN(iterator->this_arg_size); + + /* + * We know that without the alignment padding it was valid, so + * ignore arbitrary padding and return that we finished if no + * further TLV could fit. + */ + if (!ITERATOR_VALID(iterator, size)) + return -ENOENT; + + /* move to next entry */ + iterator->_arg += sizeof(*tlv) + TLV_LEN_ALIGN(iterator->this_arg_size); + +return_tlv: + /* and check again if we reached the end */ + if (!ITERATOR_VALID(iterator, 1)) + return -ENOENT; + + /* if it's not the end but a new TLV won't fit - error out */ + if (!ITERATOR_VALID(iterator, sizeof(*tlv))) + return -EINVAL; + + tlv = (struct ieee80211_radiotap_tlv *)iterator->_arg; + + iterator->this_arg_index = get_unaligned_le16(&tlv->type); + iterator->this_arg_size = get_unaligned_le16(&tlv->datalen); + iterator->this_arg = tlv->data; + iterator->is_radiotap_ns = + iterator->this_arg_index != IEEE80211_RADIOTAP_VENDOR_NAMESPACE; + + if (!ITERATOR_VALID(iterator, sizeof(*tlv) + iterator->this_arg_size)) + return -EINVAL; + return 0; + } + + while (1) { + int hit = 0; + int pad, align, size, subns; + guint32 oui; + + /* if no more EXT bits, that's it */ + if ((iterator->_arg_index % 32) == IEEE80211_RADIOTAP_EXT && + !(iterator->_bitmap_shifter & 1)) + return -ENOENT; + + if (!(iterator->_bitmap_shifter & 1)) + goto next_entry; /* arg not present */ + + /* get alignment/size of data */ + switch (iterator->_arg_index % 32) { + case IEEE80211_RADIOTAP_TLVS: + align = 4; + size = 0; + break; + case IEEE80211_RADIOTAP_RADIOTAP_NAMESPACE: + case IEEE80211_RADIOTAP_EXT: + align = 1; + size = 0; + break; + case IEEE80211_RADIOTAP_VENDOR_NAMESPACE: + align = 2; + size = 6; + break; + default: +#ifdef RADIOTAP_SUPPORT_OVERRIDES + if (find_override(iterator, &align, &size)) { + /* all set */ + } else +#endif + if (!iterator->current_namespace || + iterator->_arg_index >= iterator->current_namespace->n_bits) { + if (iterator->current_namespace == &radiotap_ns) + return -ENOENT; + align = 0; + } else { + align = iterator->current_namespace->align_size[iterator->_arg_index].align; + size = iterator->current_namespace->align_size[iterator->_arg_index].size; + } + if (!align) { + /* skip all subsequent data */ + int skip_size = IEEE80211_RADIOTAP_RADIOTAP_NAMESPACE - (iterator->_arg_index % 32); + /* XXX - we should report an expert info here */ + if (!iterator->_next_ns_data) + return -EINVAL; + iterator->_arg = iterator->_next_ns_data; + /* give up on this namespace */ + iterator->current_namespace = NULL; + iterator->_next_ns_data = NULL; + // Remove 1 because jump to next_entry will also shift bitmap by 1 + iterator->_bitmap_shifter >>= skip_size - 1; + iterator->_arg_index += skip_size - 1; + /* XXX - we should report an expert info here */ + if (!ITERATOR_VALID(iterator, 0)) + return -EINVAL; + goto next_entry; + } + break; + } + + /* + * arg is present, account for alignment padding + * + * Note that these alignments are relative to the start + * of the radiotap header. There is no guarantee + * that the radiotap header itself is aligned on any + * kind of boundary. + * + * The above is why get_unaligned() is used to dereference + * multibyte elements from the radiotap area. + */ + + pad = (int)((iterator->_arg - (unsigned char *)iterator->_rtheader) & (align - 1)); + + if (pad) + iterator->_arg += align - pad; + + if (iterator->_arg_index % 32 == IEEE80211_RADIOTAP_VENDOR_NAMESPACE) { + int vnslen; + + /* XXX - we should report an expert info here */ + if (!ITERATOR_VALID(iterator, size)) + return -EINVAL; + + oui = (*iterator->_arg << 16) | + (*(iterator->_arg + 1) << 8) | + *(iterator->_arg + 2); + subns = *(iterator->_arg + 3); + + find_ns(iterator, oui, subns); + + vnslen = get_unaligned_le16(iterator->_arg + 4); + iterator->_next_ns_data = iterator->_arg + size + vnslen; + if (!iterator->current_namespace) + size += vnslen; + } else if (iterator->_arg_index % 32 == IEEE80211_RADIOTAP_TLVS) { + iterator->tlv_mode = 1; + goto return_tlv; + } + + /* + * this is what we will return to user, but we need to + * move on first so next call has something fresh to test + */ + iterator->this_arg_index = iterator->_arg_index; + iterator->this_arg = iterator->_arg; + iterator->this_arg_size = size; + + /* internally move on the size of this arg */ + iterator->_arg += size; + + /* + * check for insanity where we are given a bitmap that + * claims to have more arg content than the length of the + * radiotap section. We will normally end up equalling this + * max_length on the last arg, never exceeding it. + */ + /* XXX - we should report an expert info here */ + if (!ITERATOR_VALID(iterator, 0)) + return -EINVAL; + + /* these special ones are valid in each bitmap word */ + switch (iterator->_arg_index % 32) { + case IEEE80211_RADIOTAP_VENDOR_NAMESPACE: + iterator->_reset_on_ext = 1; + + iterator->is_radiotap_ns = 0; + /* + * If parser didn't register this vendor + * namespace with us, allow it to show it + * as 'raw. Do do that, set argument index + * to vendor namespace. + */ + iterator->this_arg_index = + IEEE80211_RADIOTAP_VENDOR_NAMESPACE; + if (!iterator->current_namespace) + hit = 1; + goto next_entry; + case IEEE80211_RADIOTAP_RADIOTAP_NAMESPACE: + iterator->_reset_on_ext = 1; + iterator->current_namespace = &radiotap_ns; + iterator->is_radiotap_ns = 1; + goto next_entry; + case IEEE80211_RADIOTAP_EXT: + /* + * bit 31 was set, there is more + * -- move to next u32 bitmap + */ + iterator->_bitmap_shifter = + get_unaligned_le32(iterator->_next_bitmap); + iterator->_next_bitmap++; + if (iterator->_reset_on_ext) + iterator->_arg_index = 0; + else + iterator->_arg_index++; + iterator->_reset_on_ext = 0; + break; + default: + /* we've got a hit! */ + hit = 1; + next_entry: + iterator->_bitmap_shifter >>= 1; + iterator->_arg_index++; + } + + /* if we found a valid arg earlier, return it now */ + if (hit) + return 0; + } +} + +/* + * Editor modelines - https://www.wireshark.org/tools/modelines.html + * + * Local variables: + * c-basic-offset: 8 + * tab-width: 8 + * indent-tabs-mode: t + * End: + * + * vi: set shiftwidth=8 tabstop=8 noexpandtab: + * :indentSize=8:tabSize=8:noTabs=false: + */ |