From 5ab4a6c81eb3dbe32361791d1535f9153f79b0ed Mon Sep 17 00:00:00 2001 From: David L Stevens Date: Tue, 27 Dec 2005 14:03:00 -0800 Subject: [PATCH] [IPV6] mcast: Fix multiple issues in MLDv2 reports. The below "jumbo" patch fixes the following problems in MLDv2. 1) Add necessary "ntohs" to recent "pskb_may_pull" check [breaks all nonzero source queries on little-endian (!)] 2) Add locking to source filter list [resend of prior patch] 3) fix "mld_marksources()" to a) send nothing when all queried sources are excluded b) send full exclude report when source queried sources are not excluded c) don't schedule a timer when there's nothing to report NOTE: RFC 3810 specifies the source list should be saved and each source reported individually as an IS_IN. This is an obvious DOS path, requiring the host to store and then multicast as many sources as are queried (e.g., millions...). This alternative sends a full, relevant report that's limited to number of sources present on the machine. 4) fix "add_grec()" to send empty-source records when it should The original check doesn't account for a non-empty source list with all sources inactive; the new code keeps that short-circuit case, and also generates the group header with an empty list if needed. 5) fix mca_crcount decrement to be after add_grec(), which needs its original value These issues (other than item #1 ;-) ) were all found by Yan Zheng, much thanks! Signed-off-by: David L Stevens Signed-off-by: David S. Miller --- include/net/if_inet6.h | 1 + net/ipv6/mcast.c | 140 ++++++++++++++++++++++++++++++++--------- 2 files changed, 111 insertions(+), 30 deletions(-) diff --git a/include/net/if_inet6.h b/include/net/if_inet6.h index d8234f9bd4..eb8afe3499 100644 --- a/include/net/if_inet6.h +++ b/include/net/if_inet6.h @@ -83,6 +83,7 @@ struct ipv6_mc_socklist struct in6_addr addr; int ifindex; struct ipv6_mc_socklist *next; + rwlock_t sflock; unsigned int sfmode; /* MCAST_{INCLUDE,EXCLUDE} */ struct ip6_sf_socklist *sflist; }; diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c index 057d8619ba..f829a4ad3c 100644 --- a/net/ipv6/mcast.c +++ b/net/ipv6/mcast.c @@ -224,6 +224,7 @@ int ipv6_sock_mc_join(struct sock *sk, int ifindex, struct in6_addr *addr) mc_lst->ifindex = dev->ifindex; mc_lst->sfmode = MCAST_EXCLUDE; + mc_lst->sflock = RW_LOCK_UNLOCKED; mc_lst->sflist = NULL; /* @@ -360,6 +361,7 @@ int ip6_mc_source(int add, int omode, struct sock *sk, struct ip6_sf_socklist *psl; int i, j, rv; int leavegroup = 0; + int pmclocked = 0; int err; if (pgsr->gsr_group.ss_family != AF_INET6 || @@ -403,6 +405,9 @@ int ip6_mc_source(int add, int omode, struct sock *sk, pmc->sfmode = omode; } + write_lock_bh(&pmc->sflock); + pmclocked = 1; + psl = pmc->sflist; if (!add) { if (!psl) @@ -475,6 +480,8 @@ int ip6_mc_source(int add, int omode, struct sock *sk, /* update the interface list */ ip6_mc_add_src(idev, group, omode, 1, source, 1); done: + if (pmclocked) + write_unlock_bh(&pmc->sflock); read_unlock_bh(&ipv6_sk_mc_lock); read_unlock_bh(&idev->lock); in6_dev_put(idev); @@ -510,6 +517,8 @@ int ip6_mc_msfilter(struct sock *sk, struct group_filter *gsf) dev = idev->dev; err = 0; + read_lock_bh(&ipv6_sk_mc_lock); + if (gsf->gf_fmode == MCAST_INCLUDE && gsf->gf_numsrc == 0) { leavegroup = 1; goto done; @@ -549,6 +558,8 @@ int ip6_mc_msfilter(struct sock *sk, struct group_filter *gsf) newpsl = NULL; (void) ip6_mc_add_src(idev, group, gsf->gf_fmode, 0, NULL, 0); } + + write_lock_bh(&pmc->sflock); psl = pmc->sflist; if (psl) { (void) ip6_mc_del_src(idev, group, pmc->sfmode, @@ -558,8 +569,10 @@ int ip6_mc_msfilter(struct sock *sk, struct group_filter *gsf) (void) ip6_mc_del_src(idev, group, pmc->sfmode, 0, NULL, 0); pmc->sflist = newpsl; pmc->sfmode = gsf->gf_fmode; + write_unlock_bh(&pmc->sflock); err = 0; done: + read_unlock_bh(&ipv6_sk_mc_lock); read_unlock_bh(&idev->lock); in6_dev_put(idev); dev_put(dev); @@ -592,6 +605,11 @@ int ip6_mc_msfget(struct sock *sk, struct group_filter *gsf, dev = idev->dev; err = -EADDRNOTAVAIL; + /* + * changes to the ipv6_mc_list require the socket lock and + * a read lock on ip6_sk_mc_lock. We have the socket lock, + * so reading the list is safe. + */ for (pmc=inet6->ipv6_mc_list; pmc; pmc=pmc->next) { if (pmc->ifindex != gsf->gf_interface) @@ -614,6 +632,10 @@ int ip6_mc_msfget(struct sock *sk, struct group_filter *gsf, copy_to_user(optval, gsf, GROUP_FILTER_SIZE(0))) { return -EFAULT; } + /* changes to psl require the socket lock, a read lock on + * on ipv6_sk_mc_lock and a write lock on pmc->sflock. We + * have the socket lock, so reading here is safe. + */ for (i=0; isflock); psl = mc->sflist; if (!psl) { rv = mc->sfmode == MCAST_EXCLUDE; @@ -665,6 +688,7 @@ int inet6_mc_check(struct sock *sk, struct in6_addr *mc_addr, if (mc->sfmode == MCAST_EXCLUDE && i < psl->sl_count) rv = 0; } + read_unlock(&mc->sflock); read_unlock(&ipv6_sk_mc_lock); return rv; @@ -1068,7 +1092,8 @@ static void igmp6_group_queried(struct ifmcaddr6 *ma, unsigned long resptime) ma->mca_flags |= MAF_TIMER_RUNNING; } -static void mld_marksources(struct ifmcaddr6 *pmc, int nsrcs, +/* mark EXCLUDE-mode sources */ +static int mld_xmarksources(struct ifmcaddr6 *pmc, int nsrcs, struct in6_addr *srcs) { struct ip6_sf_list *psf; @@ -1078,13 +1103,53 @@ static void mld_marksources(struct ifmcaddr6 *pmc, int nsrcs, for (psf=pmc->mca_sources; psf; psf=psf->sf_next) { if (scount == nsrcs) break; - for (i=0; imca_sfcount[MCAST_INCLUDE] || + pmc->mca_sfcount[MCAST_EXCLUDE] != + psf->sf_count[MCAST_EXCLUDE]) + continue; + if (ipv6_addr_equal(&srcs[i], &psf->sf_addr)) { + scount++; + break; + } + } + } + pmc->mca_flags &= ~MAF_GSQUERY; + if (scount == nsrcs) /* all sources excluded */ + return 0; + return 1; +} + +static int mld_marksources(struct ifmcaddr6 *pmc, int nsrcs, + struct in6_addr *srcs) +{ + struct ip6_sf_list *psf; + int i, scount; + + if (pmc->mca_sfmode == MCAST_EXCLUDE) + return mld_xmarksources(pmc, nsrcs, srcs); + + /* mark INCLUDE-mode sources */ + + scount = 0; + for (psf=pmc->mca_sources; psf; psf=psf->sf_next) { + if (scount == nsrcs) + break; + for (i=0; isf_addr)) { psf->sf_gsresp = 1; scount++; break; } + } + } + if (!scount) { + pmc->mca_flags &= ~MAF_GSQUERY; + return 0; } + pmc->mca_flags |= MAF_GSQUERY; + return 1; } int igmp6_event_query(struct sk_buff *skb) @@ -1167,7 +1232,7 @@ int igmp6_event_query(struct sk_buff *skb) /* mark sources to include, if group & source-specific */ if (mlh2->nsrcs != 0) { if (!pskb_may_pull(skb, srcs_offset + - mlh2->nsrcs * sizeof(struct in6_addr))) { + ntohs(mlh2->nsrcs) * sizeof(struct in6_addr))) { in6_dev_put(idev); return -EINVAL; } @@ -1203,10 +1268,9 @@ int igmp6_event_query(struct sk_buff *skb) else ma->mca_flags &= ~MAF_GSQUERY; } - if (ma->mca_flags & MAF_GSQUERY) - mld_marksources(ma, ntohs(mlh2->nsrcs), - mlh2->srcs); - igmp6_group_queried(ma, max_delay); + if (!(ma->mca_flags & MAF_GSQUERY) || + mld_marksources(ma, ntohs(mlh2->nsrcs), mlh2->srcs)) + igmp6_group_queried(ma, max_delay); spin_unlock_bh(&ma->mca_lock); if (group_type != IPV6_ADDR_ANY) break; @@ -1281,7 +1345,18 @@ static int is_in(struct ifmcaddr6 *pmc, struct ip6_sf_list *psf, int type, case MLD2_MODE_IS_EXCLUDE: if (gdeleted || sdeleted) return 0; - return !((pmc->mca_flags & MAF_GSQUERY) && !psf->sf_gsresp); + if (!((pmc->mca_flags & MAF_GSQUERY) && !psf->sf_gsresp)) { + if (pmc->mca_sfmode == MCAST_INCLUDE) + return 1; + /* don't include if this source is excluded + * in all filters + */ + if (psf->sf_count[MCAST_INCLUDE]) + return 0; + return pmc->mca_sfcount[MCAST_EXCLUDE] == + psf->sf_count[MCAST_EXCLUDE]; + } + return 0; case MLD2_CHANGE_TO_INCLUDE: if (gdeleted || sdeleted) return 0; @@ -1450,7 +1525,7 @@ static struct sk_buff *add_grec(struct sk_buff *skb, struct ifmcaddr6 *pmc, struct mld2_report *pmr; struct mld2_grec *pgr = NULL; struct ip6_sf_list *psf, *psf_next, *psf_prev, **psf_list; - int scount, first, isquery, truncate; + int scount, stotal, first, isquery, truncate; if (pmc->mca_flags & MAF_NOREPORT) return skb; @@ -1460,25 +1535,13 @@ static struct sk_buff *add_grec(struct sk_buff *skb, struct ifmcaddr6 *pmc, truncate = type == MLD2_MODE_IS_EXCLUDE || type == MLD2_CHANGE_TO_EXCLUDE; + stotal = scount = 0; + psf_list = sdeleted ? &pmc->mca_tomb : &pmc->mca_sources; - if (!*psf_list) { - if (type == MLD2_ALLOW_NEW_SOURCES || - type == MLD2_BLOCK_OLD_SOURCES) - return skb; - if (pmc->mca_crcount || isquery) { - /* make sure we have room for group header and at - * least one source. - */ - if (skb && AVAILABLE(skb) < sizeof(struct mld2_grec)+ - sizeof(struct in6_addr)) { - mld_sendpack(skb); - skb = NULL; /* add_grhead will get a new one */ - } - skb = add_grhead(skb, pmc, type, &pgr); - } - return skb; - } + if (!*psf_list) + goto empty_source; + pmr = skb ? (struct mld2_report *)skb->h.raw : NULL; /* EX and TO_EX get a fresh packet, if needed */ @@ -1491,7 +1554,6 @@ static struct sk_buff *add_grec(struct sk_buff *skb, struct ifmcaddr6 *pmc, } } first = 1; - scount = 0; psf_prev = NULL; for (psf=*psf_list; psf; psf=psf_next) { struct in6_addr *psrc; @@ -1525,7 +1587,7 @@ static struct sk_buff *add_grec(struct sk_buff *skb, struct ifmcaddr6 *pmc, } psrc = (struct in6_addr *)skb_put(skb, sizeof(*psrc)); *psrc = psf->sf_addr; - scount++; + scount++; stotal++; if ((type == MLD2_ALLOW_NEW_SOURCES || type == MLD2_BLOCK_OLD_SOURCES) && psf->sf_crcount) { psf->sf_crcount--; @@ -1540,6 +1602,21 @@ static struct sk_buff *add_grec(struct sk_buff *skb, struct ifmcaddr6 *pmc, } psf_prev = psf; } + +empty_source: + if (!stotal) { + if (type == MLD2_ALLOW_NEW_SOURCES || + type == MLD2_BLOCK_OLD_SOURCES) + return skb; + if (pmc->mca_crcount || isquery) { + /* make sure we have room for group header */ + if (skb && AVAILABLE(skb) < sizeof(struct mld2_grec)) { + mld_sendpack(skb); + skb = NULL; /* add_grhead will get a new one */ + } + skb = add_grhead(skb, pmc, type, &pgr); + } + } if (pgr) pgr->grec_nsrcs = htons(scount); @@ -1621,11 +1698,11 @@ static void mld_send_cr(struct inet6_dev *idev) skb = add_grec(skb, pmc, dtype, 1, 1); } if (pmc->mca_crcount) { - pmc->mca_crcount--; if (pmc->mca_sfmode == MCAST_EXCLUDE) { type = MLD2_CHANGE_TO_INCLUDE; skb = add_grec(skb, pmc, type, 1, 0); } + pmc->mca_crcount--; if (pmc->mca_crcount == 0) { mld_clear_zeros(&pmc->mca_tomb); mld_clear_zeros(&pmc->mca_sources); @@ -1659,12 +1736,12 @@ static void mld_send_cr(struct inet6_dev *idev) /* filter mode changes */ if (pmc->mca_crcount) { - pmc->mca_crcount--; if (pmc->mca_sfmode == MCAST_EXCLUDE) type = MLD2_CHANGE_TO_EXCLUDE; else type = MLD2_CHANGE_TO_INCLUDE; skb = add_grec(skb, pmc, type, 0, 0); + pmc->mca_crcount--; } spin_unlock_bh(&pmc->mca_lock); } @@ -2023,6 +2100,9 @@ static int ip6_mc_leave_src(struct sock *sk, struct ipv6_mc_socklist *iml, { int err; + /* callers have the socket lock and a write lock on ipv6_sk_mc_lock, + * so no other readers or writers of iml or its sflist + */ if (iml->sflist == 0) { /* any-source empty exclude case */ return ip6_mc_del_src(idev, &iml->addr, iml->sfmode, 0, NULL, 0); -- 2.39.5