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| 1 | +// SPDX-License-Identifier: LGPL-2.1 |
| 2 | +/* |
| 3 | + * |
| 4 | + * Encryption and hashing operations relating to NTLM, NTLMv2. See MS-NLMP |
| 5 | + * for more detailed information |
| 6 | + * |
| 7 | + * Copyright (C) International Business Machines Corp., 2005,2013 |
| 8 | + * Author(s): Steve French (sfrench@us.ibm.com) |
| 9 | + * |
| 10 | + */ |
| 11 | + |
| 12 | +#include <linux/fips.h> |
| 13 | +#include <crypto/md5.h> |
| 14 | +#include "cifsproto.h" |
| 15 | +#include "smb1proto.h" |
| 16 | +#include "cifs_debug.h" |
| 17 | + |
| 18 | +/* |
| 19 | + * Calculate and return the CIFS signature based on the mac key and SMB PDU. |
| 20 | + * The 16 byte signature must be allocated by the caller. Note we only use the |
| 21 | + * 1st eight bytes and that the smb header signature field on input contains |
| 22 | + * the sequence number before this function is called. Also, this function |
| 23 | + * should be called with the server->srv_mutex held. |
| 24 | + */ |
| 25 | +static int cifs_calc_signature(struct smb_rqst *rqst, |
| 26 | + struct TCP_Server_Info *server, char *signature) |
| 27 | +{ |
| 28 | + struct md5_ctx ctx; |
| 29 | + |
| 30 | + if (!rqst->rq_iov || !signature || !server) |
| 31 | + return -EINVAL; |
| 32 | + if (fips_enabled) { |
| 33 | + cifs_dbg(VFS, |
| 34 | + "MD5 signature support is disabled due to FIPS\n"); |
| 35 | + return -EOPNOTSUPP; |
| 36 | + } |
| 37 | + |
| 38 | + md5_init(&ctx); |
| 39 | + md5_update(&ctx, server->session_key.response, server->session_key.len); |
| 40 | + |
| 41 | + return __cifs_calc_signature( |
| 42 | + rqst, server, signature, |
| 43 | + &(struct cifs_calc_sig_ctx){ .md5 = &ctx }); |
| 44 | +} |
| 45 | + |
| 46 | +/* must be called with server->srv_mutex held */ |
| 47 | +int cifs_sign_rqst(struct smb_rqst *rqst, struct TCP_Server_Info *server, |
| 48 | + __u32 *pexpected_response_sequence_number) |
| 49 | +{ |
| 50 | + int rc = 0; |
| 51 | + char smb_signature[20]; |
| 52 | + struct smb_hdr *cifs_pdu = (struct smb_hdr *)rqst->rq_iov[0].iov_base; |
| 53 | + |
| 54 | + if ((cifs_pdu == NULL) || (server == NULL)) |
| 55 | + return -EINVAL; |
| 56 | + |
| 57 | + spin_lock(&server->srv_lock); |
| 58 | + if (!(cifs_pdu->Flags2 & SMBFLG2_SECURITY_SIGNATURE) || |
| 59 | + server->tcpStatus == CifsNeedNegotiate) { |
| 60 | + spin_unlock(&server->srv_lock); |
| 61 | + return rc; |
| 62 | + } |
| 63 | + spin_unlock(&server->srv_lock); |
| 64 | + |
| 65 | + if (!server->session_estab) { |
| 66 | + memcpy(cifs_pdu->Signature.SecuritySignature, "BSRSPYL", 8); |
| 67 | + return rc; |
| 68 | + } |
| 69 | + |
| 70 | + cifs_pdu->Signature.Sequence.SequenceNumber = |
| 71 | + cpu_to_le32(server->sequence_number); |
| 72 | + cifs_pdu->Signature.Sequence.Reserved = 0; |
| 73 | + |
| 74 | + *pexpected_response_sequence_number = ++server->sequence_number; |
| 75 | + ++server->sequence_number; |
| 76 | + |
| 77 | + rc = cifs_calc_signature(rqst, server, smb_signature); |
| 78 | + if (rc) |
| 79 | + memset(cifs_pdu->Signature.SecuritySignature, 0, 8); |
| 80 | + else |
| 81 | + memcpy(cifs_pdu->Signature.SecuritySignature, smb_signature, 8); |
| 82 | + |
| 83 | + return rc; |
| 84 | +} |
| 85 | + |
| 86 | +int cifs_verify_signature(struct smb_rqst *rqst, |
| 87 | + struct TCP_Server_Info *server, |
| 88 | + __u32 expected_sequence_number) |
| 89 | +{ |
| 90 | + unsigned int rc; |
| 91 | + char server_response_sig[8]; |
| 92 | + char what_we_think_sig_should_be[20]; |
| 93 | + struct smb_hdr *cifs_pdu = (struct smb_hdr *)rqst->rq_iov[0].iov_base; |
| 94 | + |
| 95 | + if (cifs_pdu == NULL || server == NULL) |
| 96 | + return -EINVAL; |
| 97 | + |
| 98 | + if (!server->session_estab) |
| 99 | + return 0; |
| 100 | + |
| 101 | + if (cifs_pdu->Command == SMB_COM_LOCKING_ANDX) { |
| 102 | + struct smb_com_lock_req *pSMB = |
| 103 | + (struct smb_com_lock_req *)cifs_pdu; |
| 104 | + if (pSMB->LockType & LOCKING_ANDX_OPLOCK_RELEASE) |
| 105 | + return 0; |
| 106 | + } |
| 107 | + |
| 108 | + /* BB what if signatures are supposed to be on for session but |
| 109 | + server does not send one? BB */ |
| 110 | + |
| 111 | + /* Do not need to verify session setups with signature "BSRSPYL " */ |
| 112 | + if (memcmp(cifs_pdu->Signature.SecuritySignature, "BSRSPYL ", 8) == 0) |
| 113 | + cifs_dbg(FYI, "dummy signature received for smb command 0x%x\n", |
| 114 | + cifs_pdu->Command); |
| 115 | + |
| 116 | + /* save off the original signature so we can modify the smb and check |
| 117 | + its signature against what the server sent */ |
| 118 | + memcpy(server_response_sig, cifs_pdu->Signature.SecuritySignature, 8); |
| 119 | + |
| 120 | + cifs_pdu->Signature.Sequence.SequenceNumber = |
| 121 | + cpu_to_le32(expected_sequence_number); |
| 122 | + cifs_pdu->Signature.Sequence.Reserved = 0; |
| 123 | + |
| 124 | + cifs_server_lock(server); |
| 125 | + rc = cifs_calc_signature(rqst, server, what_we_think_sig_should_be); |
| 126 | + cifs_server_unlock(server); |
| 127 | + |
| 128 | + if (rc) |
| 129 | + return rc; |
| 130 | + |
| 131 | +/* cifs_dump_mem("what we think it should be: ", |
| 132 | + what_we_think_sig_should_be, 16); */ |
| 133 | + |
| 134 | + if (memcmp(server_response_sig, what_we_think_sig_should_be, 8)) |
| 135 | + return -EACCES; |
| 136 | + else |
| 137 | + return 0; |
| 138 | + |
| 139 | +} |
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