From c164a9ba0a8870c5c9d353f63085319931d69f23 Mon Sep 17 00:00:00 2001 From: Sridhar Samudrala Date: Tue, 22 Aug 2006 11:50:39 -0700 Subject: [PATCH] Fix sctp privilege elevation (CVE-2006-3745) sctp_make_abort_user() now takes the msg_len along with the msg so that we don't have to recalculate the bytes in iovec. It also uses memcpy_fromiovec() so that we don't go beyond the length allocated. It is good to have this fix even if verify_iovec() is fixed to return error on overflow. Signed-off-by: Sridhar Samudrala Signed-off-by: Greg Kroah-Hartman --- include/net/sctp/sctp.h | 13 ------------- include/net/sctp/sm.h | 3 +-- net/sctp/sm_make_chunk.c | 30 +++++++++--------------------- net/sctp/sm_statefuns.c | 20 ++++---------------- net/sctp/socket.c | 10 +++++++++- 5 files changed, 23 insertions(+), 53 deletions(-) diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h index a9663b49ea54..92eae0e0f3f1 100644 --- a/include/net/sctp/sctp.h +++ b/include/net/sctp/sctp.h @@ -404,19 +404,6 @@ static inline int sctp_list_single_entry(struct list_head *head) return ((head->next != head) && (head->next == head->prev)); } -/* Calculate the size (in bytes) occupied by the data of an iovec. */ -static inline size_t get_user_iov_size(struct iovec *iov, int iovlen) -{ - size_t retval = 0; - - for (; iovlen > 0; --iovlen) { - retval += iov->iov_len; - iov++; - } - - return retval; -} - /* Generate a random jitter in the range of -50% ~ +50% of input RTO. */ static inline __s32 sctp_jitter(__u32 rto) { diff --git a/include/net/sctp/sm.h b/include/net/sctp/sm.h index 1eac3d0eb7a9..de313de4fefe 100644 --- a/include/net/sctp/sm.h +++ b/include/net/sctp/sm.h @@ -221,8 +221,7 @@ struct sctp_chunk *sctp_make_abort_no_data(const struct sctp_association *, const struct sctp_chunk *, __u32 tsn); struct sctp_chunk *sctp_make_abort_user(const struct sctp_association *, - const struct sctp_chunk *, - const struct msghdr *); + const struct msghdr *, size_t msg_len); struct sctp_chunk *sctp_make_abort_violation(const struct sctp_association *, const struct sctp_chunk *, const __u8 *, diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c index 4f11f5858209..17b509282cf2 100644 --- a/net/sctp/sm_make_chunk.c +++ b/net/sctp/sm_make_chunk.c @@ -806,38 +806,26 @@ no_mem: /* Helper to create ABORT with a SCTP_ERROR_USER_ABORT error. */ struct sctp_chunk *sctp_make_abort_user(const struct sctp_association *asoc, - const struct sctp_chunk *chunk, - const struct msghdr *msg) + const struct msghdr *msg, + size_t paylen) { struct sctp_chunk *retval; - void *payload = NULL, *payoff; - size_t paylen = 0; - struct iovec *iov = NULL; - int iovlen = 0; + void *payload = NULL; + int err; - if (msg) { - iov = msg->msg_iov; - iovlen = msg->msg_iovlen; - paylen = get_user_iov_size(iov, iovlen); - } - - retval = sctp_make_abort(asoc, chunk, sizeof(sctp_errhdr_t) + paylen); + retval = sctp_make_abort(asoc, NULL, sizeof(sctp_errhdr_t) + paylen); if (!retval) goto err_chunk; if (paylen) { /* Put the msg_iov together into payload. */ - payload = kmalloc(paylen, GFP_ATOMIC); + payload = kmalloc(paylen, GFP_KERNEL); if (!payload) goto err_payload; - payoff = payload; - for (; iovlen > 0; --iovlen) { - if (copy_from_user(payoff, iov->iov_base,iov->iov_len)) - goto err_copy; - payoff += iov->iov_len; - iov++; - } + err = memcpy_fromiovec(payload, msg->msg_iov, paylen); + if (err < 0) + goto err_copy; } sctp_init_cause(retval, SCTP_ERROR_USER_ABORT, payload, paylen); diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c index ead3f1b0ea3d..5b5ae7958322 100644 --- a/net/sctp/sm_statefuns.c +++ b/net/sctp/sm_statefuns.c @@ -4031,18 +4031,12 @@ sctp_disposition_t sctp_sf_do_9_1_prm_abort( * from its upper layer, but retransmits data to the far end * if necessary to fill gaps. */ - struct msghdr *msg = arg; - struct sctp_chunk *abort; + struct sctp_chunk *abort = arg; sctp_disposition_t retval; retval = SCTP_DISPOSITION_CONSUME; - /* Generate ABORT chunk to send the peer. */ - abort = sctp_make_abort_user(asoc, NULL, msg); - if (!abort) - retval = SCTP_DISPOSITION_NOMEM; - else - sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort)); + sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort)); /* Even if we can't send the ABORT due to low memory delete the * TCB. This is a departure from our typical NOMEM handling. @@ -4166,8 +4160,7 @@ sctp_disposition_t sctp_sf_cookie_wait_prm_abort( void *arg, sctp_cmd_seq_t *commands) { - struct msghdr *msg = arg; - struct sctp_chunk *abort; + struct sctp_chunk *abort = arg; sctp_disposition_t retval; /* Stop T1-init timer */ @@ -4175,12 +4168,7 @@ sctp_disposition_t sctp_sf_cookie_wait_prm_abort( SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT)); retval = SCTP_DISPOSITION_CONSUME; - /* Generate ABORT chunk to send the peer */ - abort = sctp_make_abort_user(asoc, NULL, msg); - if (!abort) - retval = SCTP_DISPOSITION_NOMEM; - else - sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort)); + sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort)); sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE, SCTP_STATE(SCTP_STATE_CLOSED)); diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 54722e622e6d..fde3f55bfd4b 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -1520,8 +1520,16 @@ SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk, goto out_unlock; } if (sinfo_flags & SCTP_ABORT) { + struct sctp_chunk *chunk; + + chunk = sctp_make_abort_user(asoc, msg, msg_len); + if (!chunk) { + err = -ENOMEM; + goto out_unlock; + } + SCTP_DEBUG_PRINTK("Aborting association: %p\n", asoc); - sctp_primitive_ABORT(asoc, msg); + sctp_primitive_ABORT(asoc, chunk); err = 0; goto out_unlock; }