From cc3ccf26f0649089b3a34a2781977755ea36e72c Mon Sep 17 00:00:00 2001 From: Xin Long Date: Sun, 18 Nov 2018 15:21:53 +0800 Subject: sctp: not allow to set asoc prsctp_enable by sockopt As rfc7496#section4.5 says about SCTP_PR_SUPPORTED: This socket option allows the enabling or disabling of the negotiation of PR-SCTP support for future associations. For existing associations, it allows one to query whether or not PR-SCTP support was negotiated on a particular association. It means only sctp sock's prsctp_enable can be set. Note that for the limitation of SCTP_{CURRENT|ALL}_ASSOC, we will add it when introducing SCTP_{FUTURE|CURRENT|ALL}_ASSOC for linux sctp in another patchset. v1->v2: - drop the params.assoc_id check as Neil suggested. Fixes: 28aa4c26fce2 ("sctp: add SCTP_PR_SUPPORTED on sctp sockopt") Reported-by: Ying Xu Signed-off-by: Xin Long Signed-off-by: David S. Miller --- net/sctp/socket.c | 26 +++++--------------------- 1 file changed, 5 insertions(+), 21 deletions(-) (limited to 'net/sctp/socket.c') diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 739f3e50120d..bf618d1b41fd 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -3940,32 +3940,16 @@ static int sctp_setsockopt_pr_supported(struct sock *sk, unsigned int optlen) { struct sctp_assoc_value params; - struct sctp_association *asoc; - int retval = -EINVAL; if (optlen != sizeof(params)) - goto out; - - if (copy_from_user(¶ms, optval, optlen)) { - retval = -EFAULT; - goto out; - } - - asoc = sctp_id2assoc(sk, params.assoc_id); - if (asoc) { - asoc->prsctp_enable = !!params.assoc_value; - } else if (!params.assoc_id) { - struct sctp_sock *sp = sctp_sk(sk); + return -EINVAL; - sp->ep->prsctp_enable = !!params.assoc_value; - } else { - goto out; - } + if (copy_from_user(¶ms, optval, optlen)) + return -EFAULT; - retval = 0; + sctp_sk(sk)->ep->prsctp_enable = !!params.assoc_value; -out: - return retval; + return 0; } static int sctp_setsockopt_default_prinfo(struct sock *sk, -- cgit From afd0a8006e98b1890908f81746c94ca5dae29d7c Mon Sep 17 00:00:00 2001 From: Jakub Audykowicz Date: Tue, 4 Dec 2018 20:27:41 +0100 Subject: sctp: frag_point sanity check If for some reason an association's fragmentation point is zero, sctp_datamsg_from_user will try to endlessly try to divide a message into zero-sized chunks. This eventually causes kernel panic due to running out of memory. Although this situation is quite unlikely, it has occurred before as reported. I propose to add this simple last-ditch sanity check due to the severity of the potential consequences. Signed-off-by: Jakub Audykowicz Acked-by: Neil Horman Acked-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller --- include/net/sctp/sctp.h | 5 +++++ net/sctp/chunk.c | 6 ++++++ net/sctp/socket.c | 3 +-- 3 files changed, 12 insertions(+), 2 deletions(-) (limited to 'net/sctp/socket.c') diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h index ab9242e51d9e..2abbc15824af 100644 --- a/include/net/sctp/sctp.h +++ b/include/net/sctp/sctp.h @@ -620,4 +620,9 @@ static inline bool sctp_transport_pmtu_check(struct sctp_transport *t) return false; } +static inline __u32 sctp_min_frag_point(struct sctp_sock *sp, __u16 datasize) +{ + return sctp_mtu_payload(sp, SCTP_DEFAULT_MINSEGMENT, datasize); +} + #endif /* __net_sctp_h__ */ diff --git a/net/sctp/chunk.c b/net/sctp/chunk.c index ce8087846f05..d2048de86e7c 100644 --- a/net/sctp/chunk.c +++ b/net/sctp/chunk.c @@ -191,6 +191,12 @@ struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc, * the packet */ max_data = asoc->frag_point; + if (unlikely(!max_data)) { + max_data = sctp_min_frag_point(sctp_sk(asoc->base.sk), + sctp_datachk_len(&asoc->stream)); + pr_warn_ratelimited("%s: asoc:%p frag_point is zero, forcing max_data to default minimum (%Zu)", + __func__, asoc, max_data); + } /* If the the peer requested that we authenticate DATA chunks * we need to account for bundling of the AUTH chunks along with diff --git a/net/sctp/socket.c b/net/sctp/socket.c index bf618d1b41fd..b8cebd5a87e5 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -3324,8 +3324,7 @@ static int sctp_setsockopt_maxseg(struct sock *sk, char __user *optval, unsigned __u16 datasize = asoc ? sctp_datachk_len(&asoc->stream) : sizeof(struct sctp_data_chunk); - min_len = sctp_mtu_payload(sp, SCTP_DEFAULT_MINSEGMENT, - datasize); + min_len = sctp_min_frag_point(sp, datasize); max_len = SCTP_MAX_CHUNK_LEN - datasize; if (val < min_len || val > max_len) -- cgit