From 2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 Mon Sep 17 00:00:00 2001 From: Huw Davies Date: Mon, 27 Jun 2016 15:06:15 -0400 Subject: calipso: Allow the lsm to label the skbuff directly. In some cases, the lsm needs to add the label to the skbuff directly. A NF_INET_LOCAL_OUT IPv6 hook is added to selinux to match the IPv4 behaviour. This allows selinux to label the skbuffs that it requires. Signed-off-by: Huw Davies Signed-off-by: Paul Moore --- net/ipv6/calipso.c | 165 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 165 insertions(+) (limited to 'net/ipv6/calipso.c') diff --git a/net/ipv6/calipso.c b/net/ipv6/calipso.c index 067a5640ef17..fa371a8827cf 100644 --- a/net/ipv6/calipso.c +++ b/net/ipv6/calipso.c @@ -62,6 +62,11 @@ */ #define CALIPSO_OPT_LEN_MAX_WITH_PAD (3 + CALIPSO_OPT_LEN_MAX + 7) + /* Maximium size of u32 aligned buffer required to hold calipso + * option. Max of 3 initial pad bytes starting from buffer + 3. + * i.e. the worst case is when the previous tlv finishes on 4n + 3. + */ +#define CALIPSO_MAX_BUFFER (6 + CALIPSO_OPT_LEN_MAX) /* List of available DOI definitions */ static DEFINE_SPINLOCK(calipso_doi_list_lock); @@ -973,6 +978,162 @@ static void calipso_req_delattr(struct request_sock *req) kfree(new); } +/* skbuff functions. + */ + +/** + * calipso_skbuff_optptr - Find the CALIPSO option in the packet + * @skb: the packet + * + * Description: + * Parse the packet's IP header looking for a CALIPSO option. Returns a pointer + * to the start of the CALIPSO option on success, NULL if one if not found. + * + */ +static unsigned char *calipso_skbuff_optptr(const struct sk_buff *skb) +{ + const struct ipv6hdr *ip6_hdr = ipv6_hdr(skb); + int offset; + + if (ip6_hdr->nexthdr != NEXTHDR_HOP) + return NULL; + + offset = ipv6_find_tlv(skb, sizeof(*ip6_hdr), IPV6_TLV_CALIPSO); + if (offset >= 0) + return (unsigned char *)ip6_hdr + offset; + + return NULL; +} + +/** + * calipso_skbuff_setattr - Set the CALIPSO option on a packet + * @skb: the packet + * @doi_def: the CALIPSO DOI to use + * @secattr: the security attributes + * + * Description: + * Set the CALIPSO option on the given packet based on the security attributes. + * Returns a pointer to the IP header on success and NULL on failure. + * + */ +static int calipso_skbuff_setattr(struct sk_buff *skb, + const struct calipso_doi *doi_def, + const struct netlbl_lsm_secattr *secattr) +{ + int ret_val; + struct ipv6hdr *ip6_hdr; + struct ipv6_opt_hdr *hop; + unsigned char buf[CALIPSO_MAX_BUFFER]; + int len_delta, new_end, pad; + unsigned int start, end; + + ip6_hdr = ipv6_hdr(skb); + if (ip6_hdr->nexthdr == NEXTHDR_HOP) { + hop = (struct ipv6_opt_hdr *)(ip6_hdr + 1); + ret_val = calipso_opt_find(hop, &start, &end); + if (ret_val && ret_val != -ENOENT) + return ret_val; + } else { + start = 0; + end = 0; + } + + memset(buf, 0, sizeof(buf)); + ret_val = calipso_genopt(buf, start & 3, sizeof(buf), doi_def, secattr); + if (ret_val < 0) + return ret_val; + + new_end = start + ret_val; + /* At this point new_end aligns to 4n, so (new_end & 4) pads to 8n */ + pad = ((new_end & 4) + (end & 7)) & 7; + len_delta = new_end - (int)end + pad; + ret_val = skb_cow(skb, skb_headroom(skb) + len_delta); + if (ret_val < 0) + return ret_val; + + if (len_delta) { + if (len_delta > 0) + skb_push(skb, len_delta); + else + skb_pull(skb, -len_delta); + memmove((char *)ip6_hdr - len_delta, ip6_hdr, + sizeof(*ip6_hdr) + start); + skb_reset_network_header(skb); + ip6_hdr = ipv6_hdr(skb); + } + + hop = (struct ipv6_opt_hdr *)(ip6_hdr + 1); + if (start == 0) { + struct ipv6_opt_hdr *new_hop = (struct ipv6_opt_hdr *)buf; + + new_hop->nexthdr = ip6_hdr->nexthdr; + new_hop->hdrlen = len_delta / 8 - 1; + ip6_hdr->nexthdr = NEXTHDR_HOP; + } else { + hop->hdrlen += len_delta / 8; + } + memcpy((char *)hop + start, buf + (start & 3), new_end - start); + calipso_pad_write((unsigned char *)hop, new_end, pad); + + return 0; +} + +/** + * calipso_skbuff_delattr - Delete any CALIPSO options from a packet + * @skb: the packet + * + * Description: + * Removes any and all CALIPSO options from the given packet. Returns zero on + * success, negative values on failure. + * + */ +static int calipso_skbuff_delattr(struct sk_buff *skb) +{ + int ret_val; + struct ipv6hdr *ip6_hdr; + struct ipv6_opt_hdr *old_hop; + u32 old_hop_len, start = 0, end = 0, delta, size, pad; + + if (!calipso_skbuff_optptr(skb)) + return 0; + + /* since we are changing the packet we should make a copy */ + ret_val = skb_cow(skb, skb_headroom(skb)); + if (ret_val < 0) + return ret_val; + + ip6_hdr = ipv6_hdr(skb); + old_hop = (struct ipv6_opt_hdr *)(ip6_hdr + 1); + old_hop_len = ipv6_optlen(old_hop); + + ret_val = calipso_opt_find(old_hop, &start, &end); + if (ret_val) + return ret_val; + + if (start == sizeof(*old_hop) && end == old_hop_len) { + /* There's no other option in the header so we delete + * the whole thing. */ + delta = old_hop_len; + size = sizeof(*ip6_hdr); + ip6_hdr->nexthdr = old_hop->nexthdr; + } else { + delta = (end - start) & ~7; + if (delta) + old_hop->hdrlen -= delta / 8; + pad = (end - start) & 7; + size = sizeof(*ip6_hdr) + start + pad; + calipso_pad_write((unsigned char *)old_hop, start, pad); + } + + if (delta) { + skb_pull(skb, delta); + memmove((char *)ip6_hdr + delta, ip6_hdr, size); + skb_reset_network_header(skb); + } + + return 0; +} + static const struct netlbl_calipso_ops ops = { .doi_add = calipso_doi_add, .doi_free = calipso_doi_free, @@ -985,6 +1146,10 @@ static const struct netlbl_calipso_ops ops = { .sock_delattr = calipso_sock_delattr, .req_setattr = calipso_req_setattr, .req_delattr = calipso_req_delattr, + .opt_getattr = calipso_opt_getattr, + .skbuff_optptr = calipso_skbuff_optptr, + .skbuff_setattr = calipso_skbuff_setattr, + .skbuff_delattr = calipso_skbuff_delattr, }; /** -- cgit v1.2.3