diff options
| author | Steve French <smfrench@gmail.com> | 2018-04-08 23:14:31 +0200 |
|---|---|---|
| committer | Steve French <smfrench@gmail.com> | 2018-04-12 23:52:38 +0200 |
| commit | 136ff1b4b65edf09b6b7173ba94ad53347d3aa83 (patch) | |
| tree | a3637b5dc7de1c91869b111f10eed9736f8a7d96 /fs | |
| parent | CIFS: add ONCE flag for cifs_dbg type (diff) | |
| download | linux-136ff1b4b65edf09b6b7173ba94ad53347d3aa83.tar.xz linux-136ff1b4b65edf09b6b7173ba94ad53347d3aa83.zip | |
SMB3: Fix length checking of SMB3.11 negotiate request
The length checking for SMB3.11 negotiate request includes
"negotiate contexts" which caused a buffer validation problem
and a confusing warning message on SMB3.11 mount e.g.:
SMB2 server sent bad RFC1001 len 236 not 170
Fix the length checking for SMB3.11 negotiate to account for
the new negotiate context so that we don't log a warning on
SMB3.11 mount by default but do log warnings if lengths returned
by the server are incorrect.
CC: Stable <stable@vger.kernel.org>
Signed-off-by: Steve French <smfrench@gmail.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/cifs/smb2misc.c | 39 | ||||
| -rw-r--r-- | fs/cifs/smb2pdu.h | 7 |
2 files changed, 46 insertions, 0 deletions
diff --git a/fs/cifs/smb2misc.c b/fs/cifs/smb2misc.c index 5406e95f5d92..9df9f0b48160 100644 --- a/fs/cifs/smb2misc.c +++ b/fs/cifs/smb2misc.c @@ -93,6 +93,41 @@ static const __le16 smb2_rsp_struct_sizes[NUMBER_OF_SMB2_COMMANDS] = { /* SMB2_OPLOCK_BREAK */ cpu_to_le16(24) }; +#ifdef CONFIG_CIFS_SMB311 +static __u32 get_neg_ctxt_len(struct smb2_hdr *hdr, __u32 len, __u32 non_ctxlen) +{ + __u16 neg_count; + __u32 nc_offset, size_of_pad_before_neg_ctxts; + struct smb2_negotiate_rsp *pneg_rsp = (struct smb2_negotiate_rsp *)hdr; + + /* Negotiate contexts are only valid for latest dialect SMB3.11 */ + neg_count = le16_to_cpu(pneg_rsp->NegotiateContextCount); + if ((neg_count == 0) || + (pneg_rsp->DialectRevision != cpu_to_le16(SMB311_PROT_ID))) + return 0; + + /* Make sure that negotiate contexts start after gss security blob */ + nc_offset = le32_to_cpu(pneg_rsp->NegotiateContextOffset); + if (nc_offset < non_ctxlen - 4 /* RFC1001 len field */) { + printk_once(KERN_WARNING "invalid negotiate context offset\n"); + return 0; + } + size_of_pad_before_neg_ctxts = nc_offset - (non_ctxlen - 4); + + /* Verify that at least minimal negotiate contexts fit within frame */ + if (len < nc_offset + (neg_count * sizeof(struct smb2_neg_context))) { + printk_once(KERN_WARNING "negotiate context goes beyond end\n"); + return 0; + } + + cifs_dbg(FYI, "length of negcontexts %d pad %d\n", + len - nc_offset, size_of_pad_before_neg_ctxts); + + /* length of negcontexts including pad from end of sec blob to them */ + return (len - nc_offset) + size_of_pad_before_neg_ctxts; +} +#endif /* CIFS_SMB311 */ + int smb2_check_message(char *buf, unsigned int length, struct TCP_Server_Info *srvr) { @@ -198,6 +233,10 @@ smb2_check_message(char *buf, unsigned int length, struct TCP_Server_Info *srvr) clc_len = smb2_calc_size(hdr); +#ifdef CONFIG_CIFS_SMB311 + if (shdr->Command == SMB2_NEGOTIATE) + clc_len += get_neg_ctxt_len(hdr, len, clc_len); +#endif /* SMB311 */ if (srvr->vals->header_preamble_size + len != clc_len) { cifs_dbg(FYI, "Calculated size %u length %zu mismatch mid %llu\n", clc_len, srvr->vals->header_preamble_size + len, mid); diff --git a/fs/cifs/smb2pdu.h b/fs/cifs/smb2pdu.h index 253e2c7c952f..0e0a0af89e4d 100644 --- a/fs/cifs/smb2pdu.h +++ b/fs/cifs/smb2pdu.h @@ -263,6 +263,13 @@ struct smb2_negotiate_req { #define SMB2_NT_FIND 0x00100000 #define SMB2_LARGE_FILES 0x00200000 +struct smb2_neg_context { + __le16 ContextType; + __le16 DataLength; + __le32 Reserved; + /* Followed by array of data */ +} __packed; + #define SMB311_SALT_SIZE 32 /* Hash Algorithm Types */ #define SMB2_PREAUTH_INTEGRITY_SHA512 cpu_to_le16(0x0001) |