From acc58d0bab55a50e02c25f00bd6a210ee121595f Mon Sep 17 00:00:00 2001 From: Pavel Shilovsky Date: Thu, 17 Jan 2019 08:21:24 -0800 Subject: CIFS: Fix possible hang during async MTU reads and writes When doing MTU i/o we need to leave some credits for possible reopen requests and other operations happening in parallel. Currently we leave 1 credit which is not enough even for reopen only: we need at least 2 credits if durable handle reconnect fails. Also there may be other operations at the same time including compounding ones which require 3 credits at a time each. Fix this by leaving 8 credits which is big enough to cover most scenarios. Was able to reproduce this when server was configured to give out fewer credits than usual. The proper fix would be to reconnect a file handle first and then obtain credits for an MTU request but this leads to bigger code changes and should happen in other patches. Cc: Signed-off-by: Pavel Shilovsky Signed-off-by: Steve French --- fs/cifs/smb2ops.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'fs/cifs/smb2ops.c') diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c index cf7eb891804f..1d3ce127b02e 100644 --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -165,14 +165,14 @@ smb2_wait_mtu_credits(struct TCP_Server_Info *server, unsigned int size, scredits = server->credits; /* can deadlock with reopen */ - if (scredits == 1) { + if (scredits <= 8) { *num = SMB2_MAX_BUFFER_SIZE; *credits = 0; break; } - /* leave one credit for a possible reopen */ - scredits--; + /* leave some credits for reopen and other ops */ + scredits -= 8; *num = min_t(unsigned int, size, scredits * SMB2_MAX_BUFFER_SIZE); -- cgit v1.2.3 From ef68e831840c40c7d01b328b3c0f5d8c4796c232 Mon Sep 17 00:00:00 2001 From: Pavel Shilovsky Date: Fri, 18 Jan 2019 17:25:36 -0800 Subject: CIFS: Do not reconnect TCP session in add_credits() When executing add_credits() we currently call cifs_reconnect() if the number of credits is zero and there are no requests in flight. In this case we may call cifs_reconnect() recursively twice and cause memory corruption given the following sequence of functions: mid1.callback() -> add_credits() -> cifs_reconnect() -> -> mid2.callback() -> add_credits() -> cifs_reconnect(). Fix this by avoiding to call cifs_reconnect() in add_credits() and checking for zero credits in the demultiplex thread. Cc: Signed-off-by: Pavel Shilovsky Reviewed-by: Ronnie Sahlberg Signed-off-by: Steve French --- fs/cifs/connect.c | 21 +++++++++++++++++++++ fs/cifs/smb2ops.c | 32 +++++++++++++++++++++++++------- 2 files changed, 46 insertions(+), 7 deletions(-) (limited to 'fs/cifs/smb2ops.c') diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index 683310f26171..8463c940e0e5 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -720,6 +720,21 @@ server_unresponsive(struct TCP_Server_Info *server) return false; } +static inline bool +zero_credits(struct TCP_Server_Info *server) +{ + int val; + + spin_lock(&server->req_lock); + val = server->credits + server->echo_credits + server->oplock_credits; + if (server->in_flight == 0 && val == 0) { + spin_unlock(&server->req_lock); + return true; + } + spin_unlock(&server->req_lock); + return false; +} + static int cifs_readv_from_socket(struct TCP_Server_Info *server, struct msghdr *smb_msg) { @@ -732,6 +747,12 @@ cifs_readv_from_socket(struct TCP_Server_Info *server, struct msghdr *smb_msg) for (total_read = 0; msg_data_left(smb_msg); total_read += length) { try_to_freeze(); + /* reconnect if no credits and no requests in flight */ + if (zero_credits(server)) { + cifs_reconnect(server); + return -ECONNABORTED; + } + if (server_unresponsive(server)) return -ECONNABORTED; if (cifs_rdma_enabled(server) && server->smbd_conn) diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c index 1d3ce127b02e..fa8d2e1076c8 100644 --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -34,6 +34,7 @@ #include "cifs_ioctl.h" #include "smbdirect.h" +/* Change credits for different ops and return the total number of credits */ static int change_conf(struct TCP_Server_Info *server) { @@ -41,17 +42,15 @@ change_conf(struct TCP_Server_Info *server) server->oplock_credits = server->echo_credits = 0; switch (server->credits) { case 0: - return -1; + return 0; case 1: server->echoes = false; server->oplocks = false; - cifs_dbg(VFS, "disabling echoes and oplocks\n"); break; case 2: server->echoes = true; server->oplocks = false; server->echo_credits = 1; - cifs_dbg(FYI, "disabling oplocks\n"); break; default: server->echoes = true; @@ -64,14 +63,15 @@ change_conf(struct TCP_Server_Info *server) server->echo_credits = 1; } server->credits -= server->echo_credits + server->oplock_credits; - return 0; + return server->credits + server->echo_credits + server->oplock_credits; } static void smb2_add_credits(struct TCP_Server_Info *server, const unsigned int add, const int optype) { - int *val, rc = 0; + int *val, rc = -1; + spin_lock(&server->req_lock); val = server->ops->get_credits_field(server, optype); @@ -101,8 +101,26 @@ smb2_add_credits(struct TCP_Server_Info *server, const unsigned int add, } spin_unlock(&server->req_lock); wake_up(&server->request_q); - if (rc) - cifs_reconnect(server); + + if (server->tcpStatus == CifsNeedReconnect) + return; + + switch (rc) { + case -1: + /* change_conf hasn't been executed */ + break; + case 0: + cifs_dbg(VFS, "Possible client or server bug - zero credits\n"); + break; + case 1: + cifs_dbg(VFS, "disabling echoes and oplocks\n"); + break; + case 2: + cifs_dbg(FYI, "disabling oplocks\n"); + break; + default: + cifs_dbg(FYI, "add %u credits total=%d\n", add, rc); + } } static void -- cgit v1.2.3 From ec678eae746dd25766a61c4095e2b649d3b20b09 Mon Sep 17 00:00:00 2001 From: Pavel Shilovsky Date: Fri, 18 Jan 2019 15:38:11 -0800 Subject: CIFS: Fix credit calculation for encrypted reads with errors We do need to account for credits received in error responses to read requests on encrypted sessions. Cc: Signed-off-by: Pavel Shilovsky Reviewed-by: Ronnie Sahlberg Signed-off-by: Steve French --- fs/cifs/smb2ops.c | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-) (limited to 'fs/cifs/smb2ops.c') diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c index fa8d2e1076c8..73f9c6af4065 100644 --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -3207,11 +3207,23 @@ handle_read_data(struct TCP_Server_Info *server, struct mid_q_entry *mid, server->ops->is_status_pending(buf, server, 0)) return -1; - rdata->result = server->ops->map_error(buf, false); + /* set up first two iov to get credits */ + rdata->iov[0].iov_base = buf; + rdata->iov[0].iov_len = 4; + rdata->iov[1].iov_base = buf + 4; + rdata->iov[1].iov_len = + min_t(unsigned int, buf_len, server->vals->read_rsp_size) - 4; + cifs_dbg(FYI, "0: iov_base=%p iov_len=%zu\n", + rdata->iov[0].iov_base, rdata->iov[0].iov_len); + cifs_dbg(FYI, "1: iov_base=%p iov_len=%zu\n", + rdata->iov[1].iov_base, rdata->iov[1].iov_len); + + rdata->result = server->ops->map_error(buf, true); if (rdata->result != 0) { cifs_dbg(FYI, "%s: server returned error %d\n", __func__, rdata->result); - dequeue_mid(mid, rdata->result); + /* normal error on read response */ + dequeue_mid(mid, false); return 0; } @@ -3284,14 +3296,6 @@ handle_read_data(struct TCP_Server_Info *server, struct mid_q_entry *mid, return 0; } - /* set up first iov for signature check */ - rdata->iov[0].iov_base = buf; - rdata->iov[0].iov_len = 4; - rdata->iov[1].iov_base = buf + 4; - rdata->iov[1].iov_len = server->vals->read_rsp_size - 4; - cifs_dbg(FYI, "0: iov_base=%p iov_len=%zu\n", - rdata->iov[0].iov_base, server->vals->read_rsp_size); - length = rdata->copy_into_pages(server, rdata, &iter); kfree(bvec); -- cgit v1.2.3 From 3d3003fce8e837acc4e3960fe3cbabebc356dcb5 Mon Sep 17 00:00:00 2001 From: Pavel Shilovsky Date: Tue, 22 Jan 2019 16:50:21 -0800 Subject: CIFS: Fix credit calculations in compound mid callback The current code doesn't do proper accounting for credits in SMB1 case: it adds one credit per response only if we get a complete response while it needs to return it unconditionally. Fix this and also include malformed responses for SMB2+ into accounting for credits because such responses have Credit Granted field, thus nothing prevents to get a proper credit value from them. Signed-off-by: Pavel Shilovsky Reviewed-by: Ronnie Sahlberg Signed-off-by: Steve French --- fs/cifs/smb2ops.c | 6 +++++- fs/cifs/transport.c | 11 +---------- 2 files changed, 6 insertions(+), 11 deletions(-) (limited to 'fs/cifs/smb2ops.c') diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c index 73f9c6af4065..153238fc4fa9 100644 --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -154,7 +154,11 @@ smb2_get_credits(struct mid_q_entry *mid) { struct smb2_sync_hdr *shdr = (struct smb2_sync_hdr *)mid->resp_buf; - return le16_to_cpu(shdr->CreditRequest); + if (mid->mid_state == MID_RESPONSE_RECEIVED + || mid->mid_state == MID_RESPONSE_MALFORMED) + return le16_to_cpu(shdr->CreditRequest); + + return 0; } static int diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c index 202e0e84efdd..53532bd3f50d 100644 --- a/fs/cifs/transport.c +++ b/fs/cifs/transport.c @@ -786,17 +786,8 @@ static void cifs_compound_callback(struct mid_q_entry *mid) { struct TCP_Server_Info *server = mid->server; - unsigned int optype = mid->optype; - unsigned int credits_received = 0; - if (mid->mid_state == MID_RESPONSE_RECEIVED) { - if (mid->resp_buf) - credits_received = server->ops->get_credits(mid); - else - cifs_dbg(FYI, "Bad state for cancelled MID\n"); - } - - add_credits(server, credits_received, optype); + add_credits(server, server->ops->get_credits(mid), mid->optype); } static void -- cgit v1.2.3 From c4627e66f73a28c5515b908c90c2bf7120086497 Mon Sep 17 00:00:00 2001 From: Ronnie Sahlberg Date: Tue, 29 Jan 2019 12:46:17 +1000 Subject: cifs: limit amount of data we request for xattrs to CIFSMaxBufSize minus the various headers and blobs that will be part of the reply. or else we might trigger a session reconnect. Signed-off-by: Ronnie Sahlberg Signed-off-by: Steve French Reviewed-by: Pavel Shilovsky --- fs/cifs/smb2ops.c | 4 +++- fs/cifs/smb2pdu.h | 15 +++++++++++++-- 2 files changed, 16 insertions(+), 3 deletions(-) (limited to 'fs/cifs/smb2ops.c') diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c index 153238fc4fa9..6f96e2292856 100644 --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -866,7 +866,9 @@ smb2_query_eas(const unsigned int xid, struct cifs_tcon *tcon, FILE_READ_EA, FILE_FULL_EA_INFORMATION, SMB2_O_INFO_FILE, - SMB2_MAX_EA_BUF, + CIFSMaxBufSize - + MAX_SMB2_CREATE_RESPONSE_SIZE - + MAX_SMB2_CLOSE_RESPONSE_SIZE, &rsp_iov, &buftype, cifs_sb); if (rc) { /* diff --git a/fs/cifs/smb2pdu.h b/fs/cifs/smb2pdu.h index e9cc6775df21..538e2299805f 100644 --- a/fs/cifs/smb2pdu.h +++ b/fs/cifs/smb2pdu.h @@ -85,6 +85,7 @@ #define NUMBER_OF_SMB2_COMMANDS 0x0013 /* 52 transform hdr + 64 hdr + 88 create rsp */ +#define SMB2_TRANSFORM_HEADER_SIZE 52 #define MAX_SMB2_HDR_SIZE 204 #define SMB2_PROTO_NUMBER cpu_to_le32(0x424d53fe) @@ -648,6 +649,13 @@ struct smb2_create_req { __u8 Buffer[0]; } __packed; +/* + * Maximum size of a SMB2_CREATE response is 64 (smb2 header) + + * 88 (fixed part of create response) + 520 (path) + 150 (contexts) + + * 2 bytes of padding. + */ +#define MAX_SMB2_CREATE_RESPONSE_SIZE 824 + struct smb2_create_rsp { struct smb2_sync_hdr sync_hdr; __le16 StructureSize; /* Must be 89 */ @@ -996,6 +1004,11 @@ struct smb2_close_req { __u64 VolatileFileId; /* opaque endianness */ } __packed; +/* + * Maximum size of a SMB2_CLOSE response is 64 (smb2 header) + 60 (data) + */ +#define MAX_SMB2_CLOSE_RESPONSE_SIZE 124 + struct smb2_close_rsp { struct smb2_sync_hdr sync_hdr; __le16 StructureSize; /* 60 */ @@ -1398,8 +1411,6 @@ struct smb2_file_link_info { /* encoding of request for level 11 */ char FileName[0]; /* Name to be assigned to new link */ } __packed; /* level 11 Set */ -#define SMB2_MAX_EA_BUF 65536 - struct smb2_file_full_ea_info { /* encoding of response for level 15 */ __le32 next_entry_offset; __u8 flags; -- cgit v1.2.3