From: NeilBrown Date: Thu, 16 Oct 2025 13:49:57 +0000 (-0400) Subject: nfsd: ensure SEQUENCE replay sends a valid reply. X-Git-Tag: v6.18-rc6~34^2~1 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1cff14b7fc7f31363c39d0269563ce75c714f7ae;p=thirdparty%2Flinux.git nfsd: ensure SEQUENCE replay sends a valid reply. nfsd4_enc_sequence_replay() uses nfsd4_encode_operation() to encode a new SEQUENCE reply when replaying a request from the slot cache - only ops after the SEQUENCE are replayed from the cache in ->sl_data. However it does this in nfsd4_replay_cache_entry() which is called *before* nfsd4_sequence() has filled in reply fields. This means that in the replayed SEQUENCE reply: maxslots will be whatever the client sent target_maxslots will be -1 (assuming init to zero, and nfsd4_encode_sequence() subtracts 1) status_flags will be zero The incorrect maxslots value, in particular, can cause the client to think the slot table has been reduced in size so it can discard its knowledge of current sequence number of the later slots, though the server has not discarded those slots. When the client later wants to use a later slot, it can get NFS4ERR_SEQ_MISORDERED from the server. This patch moves the setup of the reply into a new helper function and call it *before* nfsd4_replay_cache_entry() is called. Only one of the updated fields was used after this point - maxslots. So the nfsd4_sequence struct has been extended to have separate maxslots for the request and the response. Reported-by: Olga Kornievskaia Closes: https://lore.kernel.org/linux-nfs/20251010194449.10281-1-okorniev@redhat.com/ Tested-by: Olga Kornievskaia Signed-off-by: NeilBrown Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever --- diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index c8c326679dca..8a6960500217 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -4363,6 +4363,36 @@ static bool replay_matches_cache(struct svc_rqst *rqstp, return true; } +/* + * Note that the response is constructed here both for the case + * of a new SEQUENCE request and for a replayed SEQUENCE request. + * We do not cache SEQUENCE responses as SEQUENCE is idempotent. + */ +static void nfsd4_construct_sequence_response(struct nfsd4_session *session, + struct nfsd4_sequence *seq) +{ + struct nfs4_client *clp = session->se_client; + + seq->maxslots_response = max(session->se_target_maxslots, + seq->maxslots); + seq->target_maxslots = session->se_target_maxslots; + + switch (clp->cl_cb_state) { + case NFSD4_CB_DOWN: + seq->status_flags = SEQ4_STATUS_CB_PATH_DOWN; + break; + case NFSD4_CB_FAULT: + seq->status_flags = SEQ4_STATUS_BACKCHANNEL_FAULT; + break; + default: + seq->status_flags = 0; + } + if (!list_empty(&clp->cl_revoked)) + seq->status_flags |= SEQ4_STATUS_RECALLABLE_STATE_REVOKED; + if (atomic_read(&clp->cl_admin_revoked)) + seq->status_flags |= SEQ4_STATUS_ADMIN_STATE_REVOKED; +} + __be32 nfsd4_sequence(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, union nfsd4_op_u *u) @@ -4412,6 +4442,9 @@ nfsd4_sequence(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, dprintk("%s: slotid %d\n", __func__, seq->slotid); trace_nfsd_slot_seqid_sequence(clp, seq, slot); + + nfsd4_construct_sequence_response(session, seq); + status = check_slot_seqid(seq->seqid, slot->sl_seqid, slot->sl_flags); if (status == nfserr_replay_cache) { status = nfserr_seq_misordered; @@ -4509,23 +4542,6 @@ nfsd4_sequence(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, } out: - seq->maxslots = max(session->se_target_maxslots, seq->maxslots); - seq->target_maxslots = session->se_target_maxslots; - - switch (clp->cl_cb_state) { - case NFSD4_CB_DOWN: - seq->status_flags = SEQ4_STATUS_CB_PATH_DOWN; - break; - case NFSD4_CB_FAULT: - seq->status_flags = SEQ4_STATUS_BACKCHANNEL_FAULT; - break; - default: - seq->status_flags = 0; - } - if (!list_empty(&clp->cl_revoked)) - seq->status_flags |= SEQ4_STATUS_RECALLABLE_STATE_REVOKED; - if (atomic_read(&clp->cl_admin_revoked)) - seq->status_flags |= SEQ4_STATUS_ADMIN_STATE_REVOKED; trace_nfsd_seq4_status(rqstp, seq); out_no_session: if (conn) diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c index cf5df0f50208..67bb9c0b9fcb 100644 --- a/fs/nfsd/nfs4xdr.c +++ b/fs/nfsd/nfs4xdr.c @@ -5073,7 +5073,7 @@ nfsd4_encode_sequence(struct nfsd4_compoundres *resp, __be32 nfserr, return nfserr; /* Note slotid's are numbered from zero: */ /* sr_highest_slotid */ - nfserr = nfsd4_encode_slotid4(xdr, seq->maxslots - 1); + nfserr = nfsd4_encode_slotid4(xdr, seq->maxslots_response - 1); if (nfserr != nfs_ok) return nfserr; /* sr_target_highest_slotid */ diff --git a/fs/nfsd/xdr4.h b/fs/nfsd/xdr4.h index ee0570cbdd9e..1ce8e12ae335 100644 --- a/fs/nfsd/xdr4.h +++ b/fs/nfsd/xdr4.h @@ -574,8 +574,9 @@ struct nfsd4_sequence { struct nfs4_sessionid sessionid; /* request/response */ u32 seqid; /* request/response */ u32 slotid; /* request/response */ - u32 maxslots; /* request/response */ + u32 maxslots; /* request */ u32 cachethis; /* request */ + u32 maxslots_response; /* response */ u32 target_maxslots; /* response */ u32 status_flags; /* response */ };