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authorTim Gardner <tim.gardner@canonical.com>2013-11-02 12:50:34 -0500
committerSteve French <smfrench@gmail.com>2013-11-02 12:51:53 -0500
commit3d378d3fd82a759d59c60d89b4559bf325d7e668 (patch)
tree1fc4634672bc18c7af79f1029d42e99869beb2c4 /fs/cifs/misc.c
parent944d6f1a5b8f42a780a65378e5f52bea3ae0ce07 (diff)
downloadlinux-3d378d3fd82a759d59c60d89b4559bf325d7e668.tar.bz2
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 <jlayton@redhat.com> Signed-off-by: Tim Gardner <timg@tpi.com> Signed-off-by: Steve French <smfrench@gmail.com>
Diffstat (limited to 'fs/cifs/misc.c')
-rw-r--r--fs/cifs/misc.c10
1 files changed, 6 insertions, 4 deletions
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;
}
}