From 3d378d3fd82a759d59c60d89b4559bf325d7e668 Mon Sep 17 00:00:00 2001 From: Tim Gardner Date: Sat, 2 Nov 2013 12:50:34 -0500 Subject: [PATCH] cifs: Make big endian multiplex ID sequences monotonic on the wire The multiplex identifier (MID) in the SMB header is only ever used by the client, in conjunction with PID, to match responses from the server. As such, the endianess of the MID is not important. However, When tracing packet sequences on the wire, protocol analyzers such as wireshark display MID as little endian. It is much more informative for the on-the-wire MID sequences to match debug information emitted by the CIFS driver. Therefore, one should write and read MID in the SMB header assuming it is always little endian. Observed from wireshark during the protocol negotiation and session setup: Multiplex ID: 256 Multiplex ID: 256 Multiplex ID: 512 Multiplex ID: 512 Multiplex ID: 768 Multiplex ID: 768 After this patch on-the-wire MID values begin at 1 and increase monotonically. Introduce get_next_mid64() for the internal consumers that use the full 64 bit multiplex identifier. Introduce the helpers get_mid() and compare_mid() to make the endian translation clear. Reviewed-by: Jeff Layton Signed-off-by: Tim Gardner Signed-off-by: Steve French --- fs/cifs/cifsglob.h | 25 ++++++++++++++++++++++++- fs/cifs/cifspdu.h | 2 +- fs/cifs/misc.c | 10 ++++++---- fs/cifs/smb1ops.c | 4 ++-- fs/cifs/smb2transport.c | 2 +- fs/cifs/transport.c | 2 +- 6 files changed, 35 insertions(+), 10 deletions(-) diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h index 06e8947fc370..670da1e55be7 100644 --- a/fs/cifs/cifsglob.h +++ b/fs/cifs/cifsglob.h @@ -622,11 +622,34 @@ set_credits(struct TCP_Server_Info *server, const int val) } static inline __u64 -get_next_mid(struct TCP_Server_Info *server) +get_next_mid64(struct TCP_Server_Info *server) { return server->ops->get_next_mid(server); } +static inline __le16 +get_next_mid(struct TCP_Server_Info *server) +{ + __u16 mid = get_next_mid64(server); + /* + * The value in the SMB header should be little endian for easy + * on-the-wire decoding. + */ + return cpu_to_le16(mid); +} + +static inline __u16 +get_mid(const struct smb_hdr *smb) +{ + return le16_to_cpu(smb->Mid); +} + +static inline bool +compare_mid(__u16 mid, const struct smb_hdr *smb) +{ + return mid == le16_to_cpu(smb->Mid); +} + /* * When the server supports very large reads and writes via POSIX extensions, * we can allow up to 2^24-1, minus the size of a READ/WRITE_AND_X header, not diff --git a/fs/cifs/cifspdu.h b/fs/cifs/cifspdu.h index d40bd77a2392..f80f98f5ef9c 100644 --- a/fs/cifs/cifspdu.h +++ b/fs/cifs/cifspdu.h @@ -428,7 +428,7 @@ struct smb_hdr { __u16 Tid; __le16 Pid; __u16 Uid; - __u16 Mid; + __le16 Mid; __u8 WordCount; } __attribute__((packed)); diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c index 298e31e3bdc6..2f9f3790679d 100644 --- a/fs/cifs/misc.c +++ b/fs/cifs/misc.c @@ -295,7 +295,8 @@ check_smb_hdr(struct smb_hdr *smb) if (smb->Command == SMB_COM_LOCKING_ANDX) return 0; - cifs_dbg(VFS, "Server sent request, not response. mid=%u\n", smb->Mid); + cifs_dbg(VFS, "Server sent request, not response. mid=%u\n", + get_mid(smb)); return 1; } @@ -351,6 +352,7 @@ checkSMB(char *buf, unsigned int total_read) } if (4 + rfclen != clc_len) { + __u16 mid = get_mid(smb); /* check if bcc wrapped around for large read responses */ if ((rfclen > 64 * 1024) && (rfclen > clc_len)) { /* check if lengths match mod 64K */ @@ -358,11 +360,11 @@ checkSMB(char *buf, unsigned int total_read) return 0; /* bcc wrapped */ } cifs_dbg(FYI, "Calculated size %u vs length %u mismatch for mid=%u\n", - clc_len, 4 + rfclen, smb->Mid); + clc_len, 4 + rfclen, mid); if (4 + rfclen < clc_len) { cifs_dbg(VFS, "RFC1001 size %u smaller than SMB for mid=%u\n", - rfclen, smb->Mid); + rfclen, mid); return -EIO; } else if (rfclen > clc_len + 512) { /* @@ -375,7 +377,7 @@ checkSMB(char *buf, unsigned int total_read) * data to 512 bytes. */ cifs_dbg(VFS, "RFC1001 size %u more than 512 bytes larger than SMB for mid=%u\n", - rfclen, smb->Mid); + rfclen, mid); return -EIO; } } diff --git a/fs/cifs/smb1ops.c b/fs/cifs/smb1ops.c index 8233b174de3d..09ef8f322c2a 100644 --- a/fs/cifs/smb1ops.c +++ b/fs/cifs/smb1ops.c @@ -67,7 +67,7 @@ send_nt_cancel(struct TCP_Server_Info *server, void *buf, mutex_unlock(&server->srv_mutex); cifs_dbg(FYI, "issued NT_CANCEL for mid %u, rc = %d\n", - in_buf->Mid, rc); + get_mid(in_buf), rc); return rc; } @@ -101,7 +101,7 @@ cifs_find_mid(struct TCP_Server_Info *server, char *buffer) spin_lock(&GlobalMid_Lock); list_for_each_entry(mid, &server->pending_mid_q, qhead) { - if (mid->mid == buf->Mid && + if (compare_mid(mid->mid, buf) && mid->mid_state == MID_REQUEST_SUBMITTED && le16_to_cpu(mid->command) == buf->Command) { spin_unlock(&GlobalMid_Lock); diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c index 340abca3aa52..c523617eade2 100644 --- a/fs/cifs/smb2transport.c +++ b/fs/cifs/smb2transport.c @@ -466,7 +466,7 @@ smb2_verify_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server) static inline void smb2_seq_num_into_buf(struct TCP_Server_Info *server, struct smb2_hdr *hdr) { - hdr->MessageId = get_next_mid(server); + hdr->MessageId = get_next_mid64(server); } static struct mid_q_entry * diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c index 800b938e4061..0ee6d249ef6f 100644 --- a/fs/cifs/transport.c +++ b/fs/cifs/transport.c @@ -58,7 +58,7 @@ AllocMidQEntry(const struct smb_hdr *smb_buffer, struct TCP_Server_Info *server) return temp; else { memset(temp, 0, sizeof(struct mid_q_entry)); - temp->mid = smb_buffer->Mid; /* always LE */ + temp->mid = get_mid(smb_buffer); temp->pid = current->pid; temp->command = cpu_to_le16(smb_buffer->Command); cifs_dbg(FYI, "For smb_command %d\n", smb_buffer->Command); -- 2.30.2