diff options
author | Steve French <stfrench@microsoft.com> | 2021-07-05 15:05:39 -0500 |
---|---|---|
committer | Steve French <stfrench@microsoft.com> | 2021-07-09 12:48:58 -0500 |
commit | 53d31a3ffd60176af24f2f77fb3a7e567134eb90 (patch) | |
tree | a38b05a4b6d974b3e97193639e565f6d2b2faf59 /fs/cifs/smb2pdu.c | |
parent | e0a3cbcd5cef00cace01546cc6eaaa3b31940da9 (diff) | |
download | linux-53d31a3ffd60176af24f2f77fb3a7e567134eb90.tar.bz2 |
SMB3.1.1: Add support for negotiating signing algorithm
Support for faster packet signing (using GMAC instead of CMAC) can
now be negotiated to some newer servers, including Windows.
See MS-SMB2 section 2.2.3.17.
This patch adds support for sending the new negotiate context
with the first of three supported signing algorithms (AES-CMAC)
and decoding the response. A followon patch will add support
for sending the other two (including AES-GMAC, which is fastest)
and changing the signing algorithm used based on what was
negotiated.
To allow the client to request GMAC signing set module parameter
"enable_negotiate_signing" to 1.
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Pavel Shilovsky <pshilovsky@samba.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Diffstat (limited to 'fs/cifs/smb2pdu.c')
-rw-r--r-- | fs/cifs/smb2pdu.c | 85 |
1 files changed, 75 insertions, 10 deletions
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c index 962826dc3316..781d14e5f2af 100644 --- a/fs/cifs/smb2pdu.c +++ b/fs/cifs/smb2pdu.c @@ -433,6 +433,29 @@ build_compression_ctxt(struct smb2_compression_capabilities_context *pneg_ctxt) pneg_ctxt->CompressionAlgorithms[2] = SMB3_COMPRESS_LZNT1; } +static unsigned int +build_signing_ctxt(struct smb2_signing_capabilities *pneg_ctxt) +{ + unsigned int ctxt_len = sizeof(struct smb2_signing_capabilities); + unsigned short num_algs = 1; /* number of signing algorithms sent */ + + pneg_ctxt->ContextType = SMB2_SIGNING_CAPABILITIES; + /* + * Context Data length must be rounded to multiple of 8 for some servers + */ + pneg_ctxt->DataLength = cpu_to_le16(DIV_ROUND_UP( + sizeof(struct smb2_signing_capabilities) - + sizeof(struct smb2_neg_context) + + (num_algs * 2 /* sizeof u16 */), 8) * 8); + pneg_ctxt->SigningAlgorithmCount = cpu_to_le16(num_algs); + pneg_ctxt->SigningAlgorithms[0] = cpu_to_le16(SIGNING_ALG_AES_CMAC); + + ctxt_len += 2 /* sizeof le16 */ * num_algs; + ctxt_len = DIV_ROUND_UP(ctxt_len, 8) * 8; + return ctxt_len; + /* TBD add SIGNING_ALG_AES_GMAC and/or SIGNING_ALG_HMAC_SHA256 */ +} + static void build_encrypt_ctxt(struct smb2_encryption_neg_context *pneg_ctxt) { @@ -498,7 +521,7 @@ assemble_neg_contexts(struct smb2_negotiate_req *req, struct TCP_Server_Info *server, unsigned int *total_len) { char *pneg_ctxt; - unsigned int ctxt_len; + unsigned int ctxt_len, neg_context_count; if (*total_len > 200) { /* In case length corrupted don't want to overrun smb buffer */ @@ -525,6 +548,17 @@ assemble_neg_contexts(struct smb2_negotiate_req *req, *total_len += ctxt_len; pneg_ctxt += ctxt_len; + ctxt_len = build_netname_ctxt((struct smb2_netname_neg_context *)pneg_ctxt, + server->hostname); + *total_len += ctxt_len; + pneg_ctxt += ctxt_len; + + build_posix_ctxt((struct smb2_posix_neg_context *)pneg_ctxt); + *total_len += sizeof(struct smb2_posix_neg_context); + pneg_ctxt += sizeof(struct smb2_posix_neg_context); + + neg_context_count = 4; + if (server->compress_algorithm) { build_compression_ctxt((struct smb2_compression_capabilities_context *) pneg_ctxt); @@ -533,17 +567,20 @@ assemble_neg_contexts(struct smb2_negotiate_req *req, 8) * 8; *total_len += ctxt_len; pneg_ctxt += ctxt_len; - req->NegotiateContextCount = cpu_to_le16(5); - } else - req->NegotiateContextCount = cpu_to_le16(4); + neg_context_count++; + } - ctxt_len = build_netname_ctxt((struct smb2_netname_neg_context *)pneg_ctxt, - server->hostname); - *total_len += ctxt_len; - pneg_ctxt += ctxt_len; + if (enable_negotiate_signing) { + ctxt_len = build_signing_ctxt((struct smb2_signing_capabilities *) + pneg_ctxt); + *total_len += ctxt_len; + pneg_ctxt += ctxt_len; + neg_context_count++; + } + + /* check for and add transport_capabilities and signing capabilities */ + req->NegotiateContextCount = cpu_to_le16(neg_context_count); - build_posix_ctxt((struct smb2_posix_neg_context *)pneg_ctxt); - *total_len += sizeof(struct smb2_posix_neg_context); } static void decode_preauth_context(struct smb2_preauth_neg_context *ctxt) @@ -632,6 +669,31 @@ static int decode_encrypt_ctx(struct TCP_Server_Info *server, return 0; } +static void decode_signing_ctx(struct TCP_Server_Info *server, + struct smb2_signing_capabilities *pctxt) +{ + unsigned int len = le16_to_cpu(pctxt->DataLength); + + if ((len < 4) || (len > 16)) { + pr_warn_once("server sent bad signing negcontext\n"); + return; + } + if (le16_to_cpu(pctxt->SigningAlgorithmCount) != 1) { + pr_warn_once("Invalid signing algorithm count\n"); + return; + } + if (le16_to_cpu(pctxt->SigningAlgorithms[0]) > 2) { + pr_warn_once("unknown signing algorithm\n"); + return; + } + + server->signing_negotiated = true; + server->signing_algorithm = le16_to_cpu(pctxt->SigningAlgorithms[0]); + cifs_dbg(FYI, "signing algorithm %d chosen\n", + server->signing_algorithm); +} + + static int smb311_decode_neg_context(struct smb2_negotiate_rsp *rsp, struct TCP_Server_Info *server, unsigned int len_of_smb) @@ -675,6 +737,9 @@ static int smb311_decode_neg_context(struct smb2_negotiate_rsp *rsp, (struct smb2_compression_capabilities_context *)pctx); else if (pctx->ContextType == SMB2_POSIX_EXTENSIONS_AVAILABLE) server->posix_ext_supported = true; + else if (pctx->ContextType == SMB2_SIGNING_CAPABILITIES) + decode_signing_ctx(server, + (struct smb2_signing_capabilities *)pctx); else cifs_server_dbg(VFS, "unknown negcontext of type %d ignored\n", le16_to_cpu(pctx->ContextType)); |