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cifs: dynamic allocation of ntlmssp blob
In sess_auth_rawntlmssp_authenticate(), the ntlmssp blob is allocated statically and its size is an "empirical" 5*sizeof(struct _AUTHENTICATE_MESSAGE) (320B on x86_64). I don't know where this value comes from or if it was ever appropriate, but it is currently insufficient: the user and domain name in UTF16 could take 1kB by themselves. Because of that, build_ntlmssp_auth_blob() might corrupt memory (out-of-bounds write). The size of ntlmssp_blob in SMB2_sess_setup() is too small too (sizeof(struct _NEGOTIATE_MESSAGE) + 500). This patch allocates the blob dynamically in build_ntlmssp_auth_blob(). Signed-off-by: Jerome Marchand <jmarchan@redhat.com> Signed-off-by: Steve French <smfrench@gmail.com> CC: Stable <stable@vger.kernel.org>
This commit is contained in:
Jerome Marchand
Steve French
parent
202d772ba0
commit
b8da344b74
@ -133,6 +133,6 @@ typedef struct _AUTHENTICATE_MESSAGE {
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int decode_ntlmssp_challenge(char *bcc_ptr, int blob_len, struct cifs_ses *ses);
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void build_ntlmssp_negotiate_blob(unsigned char *pbuffer, struct cifs_ses *ses);
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int build_ntlmssp_auth_blob(unsigned char *pbuffer, u16 *buflen,
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int build_ntlmssp_auth_blob(unsigned char **pbuffer, u16 *buflen,
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struct cifs_ses *ses,
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const struct nls_table *nls_cp);
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@ -364,19 +364,43 @@ void build_ntlmssp_negotiate_blob(unsigned char *pbuffer,
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sec_blob->DomainName.MaximumLength = 0;
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}
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/* We do not malloc the blob, it is passed in pbuffer, because its
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maximum possible size is fixed and small, making this approach cleaner.
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This function returns the length of the data in the blob */
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int build_ntlmssp_auth_blob(unsigned char *pbuffer,
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static int size_of_ntlmssp_blob(struct cifs_ses *ses)
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{
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int sz = sizeof(AUTHENTICATE_MESSAGE) + ses->auth_key.len
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- CIFS_SESS_KEY_SIZE + CIFS_CPHTXT_SIZE + 2;
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if (ses->domainName)
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sz += 2 * strnlen(ses->domainName, CIFS_MAX_DOMAINNAME_LEN);
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else
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sz += 2;
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if (ses->user_name)
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sz += 2 * strnlen(ses->user_name, CIFS_MAX_USERNAME_LEN);
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else
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sz += 2;
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return sz;
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}
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int build_ntlmssp_auth_blob(unsigned char **pbuffer,
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u16 *buflen,
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struct cifs_ses *ses,
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const struct nls_table *nls_cp)
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{
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int rc;
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AUTHENTICATE_MESSAGE *sec_blob = (AUTHENTICATE_MESSAGE *)pbuffer;
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AUTHENTICATE_MESSAGE *sec_blob;
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__u32 flags;
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unsigned char *tmp;
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rc = setup_ntlmv2_rsp(ses, nls_cp);
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if (rc) {
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cifs_dbg(VFS, "Error %d during NTLMSSP authentication\n", rc);
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*buflen = 0;
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goto setup_ntlmv2_ret;
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}
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*pbuffer = kmalloc(size_of_ntlmssp_blob(ses), GFP_KERNEL);
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sec_blob = (AUTHENTICATE_MESSAGE *)*pbuffer;
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memcpy(sec_blob->Signature, NTLMSSP_SIGNATURE, 8);
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sec_blob->MessageType = NtLmAuthenticate;
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@ -391,7 +415,7 @@ int build_ntlmssp_auth_blob(unsigned char *pbuffer,
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flags |= NTLMSSP_NEGOTIATE_KEY_XCH;
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}
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tmp = pbuffer + sizeof(AUTHENTICATE_MESSAGE);
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tmp = *pbuffer + sizeof(AUTHENTICATE_MESSAGE);
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sec_blob->NegotiateFlags = cpu_to_le32(flags);
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sec_blob->LmChallengeResponse.BufferOffset =
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@ -399,13 +423,9 @@ int build_ntlmssp_auth_blob(unsigned char *pbuffer,
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sec_blob->LmChallengeResponse.Length = 0;
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sec_blob->LmChallengeResponse.MaximumLength = 0;
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sec_blob->NtChallengeResponse.BufferOffset = cpu_to_le32(tmp - pbuffer);
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sec_blob->NtChallengeResponse.BufferOffset =
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cpu_to_le32(tmp - *pbuffer);
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if (ses->user_name != NULL) {
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rc = setup_ntlmv2_rsp(ses, nls_cp);
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if (rc) {
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cifs_dbg(VFS, "Error %d during NTLMSSP authentication\n", rc);
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goto setup_ntlmv2_ret;
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}
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memcpy(tmp, ses->auth_key.response + CIFS_SESS_KEY_SIZE,
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ses->auth_key.len - CIFS_SESS_KEY_SIZE);
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tmp += ses->auth_key.len - CIFS_SESS_KEY_SIZE;
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@ -423,7 +443,7 @@ int build_ntlmssp_auth_blob(unsigned char *pbuffer,
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}
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if (ses->domainName == NULL) {
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sec_blob->DomainName.BufferOffset = cpu_to_le32(tmp - pbuffer);
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sec_blob->DomainName.BufferOffset = cpu_to_le32(tmp - *pbuffer);
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sec_blob->DomainName.Length = 0;
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sec_blob->DomainName.MaximumLength = 0;
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tmp += 2;
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@ -432,14 +452,14 @@ int build_ntlmssp_auth_blob(unsigned char *pbuffer,
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len = cifs_strtoUTF16((__le16 *)tmp, ses->domainName,
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CIFS_MAX_DOMAINNAME_LEN, nls_cp);
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len *= 2; /* unicode is 2 bytes each */
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sec_blob->DomainName.BufferOffset = cpu_to_le32(tmp - pbuffer);
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sec_blob->DomainName.BufferOffset = cpu_to_le32(tmp - *pbuffer);
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sec_blob->DomainName.Length = cpu_to_le16(len);
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sec_blob->DomainName.MaximumLength = cpu_to_le16(len);
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tmp += len;
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}
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if (ses->user_name == NULL) {
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sec_blob->UserName.BufferOffset = cpu_to_le32(tmp - pbuffer);
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sec_blob->UserName.BufferOffset = cpu_to_le32(tmp - *pbuffer);
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sec_blob->UserName.Length = 0;
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sec_blob->UserName.MaximumLength = 0;
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tmp += 2;
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@ -448,13 +468,13 @@ int build_ntlmssp_auth_blob(unsigned char *pbuffer,
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len = cifs_strtoUTF16((__le16 *)tmp, ses->user_name,
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CIFS_MAX_USERNAME_LEN, nls_cp);
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len *= 2; /* unicode is 2 bytes each */
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sec_blob->UserName.BufferOffset = cpu_to_le32(tmp - pbuffer);
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sec_blob->UserName.BufferOffset = cpu_to_le32(tmp - *pbuffer);
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sec_blob->UserName.Length = cpu_to_le16(len);
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sec_blob->UserName.MaximumLength = cpu_to_le16(len);
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tmp += len;
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}
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sec_blob->WorkstationName.BufferOffset = cpu_to_le32(tmp - pbuffer);
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sec_blob->WorkstationName.BufferOffset = cpu_to_le32(tmp - *pbuffer);
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sec_blob->WorkstationName.Length = 0;
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sec_blob->WorkstationName.MaximumLength = 0;
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tmp += 2;
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@ -463,19 +483,19 @@ int build_ntlmssp_auth_blob(unsigned char *pbuffer,
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(ses->ntlmssp->server_flags & NTLMSSP_NEGOTIATE_EXTENDED_SEC))
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&& !calc_seckey(ses)) {
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memcpy(tmp, ses->ntlmssp->ciphertext, CIFS_CPHTXT_SIZE);
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sec_blob->SessionKey.BufferOffset = cpu_to_le32(tmp - pbuffer);
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sec_blob->SessionKey.BufferOffset = cpu_to_le32(tmp - *pbuffer);
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sec_blob->SessionKey.Length = cpu_to_le16(CIFS_CPHTXT_SIZE);
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sec_blob->SessionKey.MaximumLength =
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cpu_to_le16(CIFS_CPHTXT_SIZE);
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tmp += CIFS_CPHTXT_SIZE;
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} else {
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sec_blob->SessionKey.BufferOffset = cpu_to_le32(tmp - pbuffer);
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sec_blob->SessionKey.BufferOffset = cpu_to_le32(tmp - *pbuffer);
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sec_blob->SessionKey.Length = 0;
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sec_blob->SessionKey.MaximumLength = 0;
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}
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*buflen = tmp - *pbuffer;
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setup_ntlmv2_ret:
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*buflen = tmp - pbuffer;
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return rc;
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}
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@ -1266,7 +1286,7 @@ sess_auth_rawntlmssp_authenticate(struct sess_data *sess_data)
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struct cifs_ses *ses = sess_data->ses;
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__u16 bytes_remaining;
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char *bcc_ptr;
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char *ntlmsspblob = NULL;
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unsigned char *ntlmsspblob = NULL;
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u16 blob_len;
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cifs_dbg(FYI, "rawntlmssp session setup authenticate phase\n");
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@ -1279,19 +1299,7 @@ sess_auth_rawntlmssp_authenticate(struct sess_data *sess_data)
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/* Build security blob before we assemble the request */
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pSMB = (SESSION_SETUP_ANDX *)sess_data->iov[0].iov_base;
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smb_buf = (struct smb_hdr *)pSMB;
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/*
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* 5 is an empirical value, large enough to hold
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* authenticate message plus max 10 of av paris,
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* domain, user, workstation names, flags, etc.
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*/
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ntlmsspblob = kzalloc(5*sizeof(struct _AUTHENTICATE_MESSAGE),
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GFP_KERNEL);
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if (!ntlmsspblob) {
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rc = -ENOMEM;
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goto out;
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}
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rc = build_ntlmssp_auth_blob(ntlmsspblob,
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rc = build_ntlmssp_auth_blob(&ntlmsspblob,
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&blob_len, ses, sess_data->nls_cp);
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if (rc)
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goto out_free_ntlmsspblob;
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@ -588,7 +588,7 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
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u16 blob_length = 0;
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struct key *spnego_key = NULL;
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char *security_blob = NULL;
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char *ntlmssp_blob = NULL;
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unsigned char *ntlmssp_blob = NULL;
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bool use_spnego = false; /* else use raw ntlmssp */
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cifs_dbg(FYI, "Session Setup\n");
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@ -713,13 +713,7 @@ ssetup_ntlmssp_authenticate:
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iov[1].iov_len = blob_length;
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} else if (phase == NtLmAuthenticate) {
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req->hdr.SessionId = ses->Suid;
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ntlmssp_blob = kzalloc(sizeof(struct _NEGOTIATE_MESSAGE) + 500,
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GFP_KERNEL);
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if (ntlmssp_blob == NULL) {
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rc = -ENOMEM;
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goto ssetup_exit;
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}
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rc = build_ntlmssp_auth_blob(ntlmssp_blob, &blob_length, ses,
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rc = build_ntlmssp_auth_blob(&ntlmssp_blob, &blob_length, ses,
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nls_cp);
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if (rc) {
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cifs_dbg(FYI, "build_ntlmssp_auth_blob failed %d\n",
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