From 80055f78a9696b7760c9f673671cb840ca9a3f46 Mon Sep 17 00:00:00 2001 From: Jerome Marchand Date: Thu, 26 May 2016 11:52:25 +0200 Subject: [PATCH] cifs: dynamic allocation of ntlmssp blob commit b8da344b74c822e966c6d19d6b2321efe82c5d97 upstream. 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 Signed-off-by: Steve French [bwh: Backported to 3.2: - Adjust context, indentation - build_ntlmssp_auth_blob() is static - Drop changes to smb2pdu.c - Use cERROR() instead of cifs_dbg(VFS, ...) - Use MAX_USERNAME_SIZE instead of CIFS_MAX_USERNAME_LEN] Signed-off-by: Ben Hutchings --- fs/cifs/sess.c | 78 +++++++++++++++++++++++++++----------------------- 1 file changed, 42 insertions(+), 36 deletions(-) diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c index 8dbfa3e75c7b..91b51e4aa80e 100644 --- a/fs/cifs/sess.c +++ b/fs/cifs/sess.c @@ -444,19 +444,43 @@ static void build_ntlmssp_negotiate_blob(unsigned char *pbuffer, sec_blob->DomainName.MaximumLength = 0; } -/* We do not malloc the blob, it is passed in pbuffer, because its - maximum possible size is fixed and small, making this approach cleaner. - This function returns the length of the data in the blob */ -static int build_ntlmssp_auth_blob(unsigned char *pbuffer, +static int size_of_ntlmssp_blob(struct cifs_ses *ses) +{ + int sz = sizeof(AUTHENTICATE_MESSAGE) + ses->auth_key.len + - CIFS_SESS_KEY_SIZE + CIFS_CPHTXT_SIZE + 2; + + if (ses->domainName) + sz += 2 * strnlen(ses->domainName, CIFS_MAX_DOMAINNAME_LEN); + else + sz += 2; + + if (ses->user_name) + sz += 2 * strnlen(ses->user_name, MAX_USERNAME_SIZE); + else + sz += 2; + + return sz; +} + +static int build_ntlmssp_auth_blob(unsigned char **pbuffer, u16 *buflen, struct cifs_ses *ses, const struct nls_table *nls_cp) { int rc; - AUTHENTICATE_MESSAGE *sec_blob = (AUTHENTICATE_MESSAGE *)pbuffer; + AUTHENTICATE_MESSAGE *sec_blob; __u32 flags; unsigned char *tmp; + rc = setup_ntlmv2_rsp(ses, nls_cp); + if (rc) { + cERROR(1, "Error %d during NTLMSSP authentication", rc); + *buflen = 0; + goto setup_ntlmv2_ret; + } + *pbuffer = kmalloc(size_of_ntlmssp_blob(ses), GFP_KERNEL); + sec_blob = (AUTHENTICATE_MESSAGE *)*pbuffer; + memcpy(sec_blob->Signature, NTLMSSP_SIGNATURE, 8); sec_blob->MessageType = NtLmAuthenticate; @@ -471,7 +495,7 @@ static int build_ntlmssp_auth_blob(unsigned char *pbuffer, flags |= NTLMSSP_NEGOTIATE_KEY_XCH; } - tmp = pbuffer + sizeof(AUTHENTICATE_MESSAGE); + tmp = *pbuffer + sizeof(AUTHENTICATE_MESSAGE); sec_blob->NegotiateFlags = cpu_to_le32(flags); sec_blob->LmChallengeResponse.BufferOffset = @@ -479,13 +503,9 @@ static int build_ntlmssp_auth_blob(unsigned char *pbuffer, sec_blob->LmChallengeResponse.Length = 0; sec_blob->LmChallengeResponse.MaximumLength = 0; - sec_blob->NtChallengeResponse.BufferOffset = cpu_to_le32(tmp - pbuffer); + sec_blob->NtChallengeResponse.BufferOffset = + cpu_to_le32(tmp - *pbuffer); if (ses->user_name != NULL) { - rc = setup_ntlmv2_rsp(ses, nls_cp); - if (rc) { - cERROR(1, "Error %d during NTLMSSP authentication", rc); - goto setup_ntlmv2_ret; - } memcpy(tmp, ses->auth_key.response + CIFS_SESS_KEY_SIZE, ses->auth_key.len - CIFS_SESS_KEY_SIZE); tmp += ses->auth_key.len - CIFS_SESS_KEY_SIZE; @@ -503,7 +523,7 @@ static int build_ntlmssp_auth_blob(unsigned char *pbuffer, } if (ses->domainName == NULL) { - sec_blob->DomainName.BufferOffset = cpu_to_le32(tmp - pbuffer); + sec_blob->DomainName.BufferOffset = cpu_to_le32(tmp - *pbuffer); sec_blob->DomainName.Length = 0; sec_blob->DomainName.MaximumLength = 0; tmp += 2; @@ -512,14 +532,14 @@ static int build_ntlmssp_auth_blob(unsigned char *pbuffer, len = cifs_strtoUCS((__le16 *)tmp, ses->domainName, MAX_USERNAME_SIZE, nls_cp); len *= 2; /* unicode is 2 bytes each */ - sec_blob->DomainName.BufferOffset = cpu_to_le32(tmp - pbuffer); + sec_blob->DomainName.BufferOffset = cpu_to_le32(tmp - *pbuffer); sec_blob->DomainName.Length = cpu_to_le16(len); sec_blob->DomainName.MaximumLength = cpu_to_le16(len); tmp += len; } if (ses->user_name == NULL) { - sec_blob->UserName.BufferOffset = cpu_to_le32(tmp - pbuffer); + sec_blob->UserName.BufferOffset = cpu_to_le32(tmp - *pbuffer); sec_blob->UserName.Length = 0; sec_blob->UserName.MaximumLength = 0; tmp += 2; @@ -528,13 +548,13 @@ static int build_ntlmssp_auth_blob(unsigned char *pbuffer, len = cifs_strtoUCS((__le16 *)tmp, ses->user_name, MAX_USERNAME_SIZE, nls_cp); len *= 2; /* unicode is 2 bytes each */ - sec_blob->UserName.BufferOffset = cpu_to_le32(tmp - pbuffer); + sec_blob->UserName.BufferOffset = cpu_to_le32(tmp - *pbuffer); sec_blob->UserName.Length = cpu_to_le16(len); sec_blob->UserName.MaximumLength = cpu_to_le16(len); tmp += len; } - sec_blob->WorkstationName.BufferOffset = cpu_to_le32(tmp - pbuffer); + sec_blob->WorkstationName.BufferOffset = cpu_to_le32(tmp - *pbuffer); sec_blob->WorkstationName.Length = 0; sec_blob->WorkstationName.MaximumLength = 0; tmp += 2; @@ -543,19 +563,19 @@ static int build_ntlmssp_auth_blob(unsigned char *pbuffer, (ses->ntlmssp->server_flags & NTLMSSP_NEGOTIATE_EXTENDED_SEC)) && !calc_seckey(ses)) { memcpy(tmp, ses->ntlmssp->ciphertext, CIFS_CPHTXT_SIZE); - sec_blob->SessionKey.BufferOffset = cpu_to_le32(tmp - pbuffer); + sec_blob->SessionKey.BufferOffset = cpu_to_le32(tmp - *pbuffer); sec_blob->SessionKey.Length = cpu_to_le16(CIFS_CPHTXT_SIZE); sec_blob->SessionKey.MaximumLength = cpu_to_le16(CIFS_CPHTXT_SIZE); tmp += CIFS_CPHTXT_SIZE; } else { - sec_blob->SessionKey.BufferOffset = cpu_to_le32(tmp - pbuffer); + sec_blob->SessionKey.BufferOffset = cpu_to_le32(tmp - *pbuffer); sec_blob->SessionKey.Length = 0; sec_blob->SessionKey.MaximumLength = 0; } + *buflen = tmp - *pbuffer; setup_ntlmv2_ret: - *buflen = tmp - pbuffer; return rc; } @@ -578,7 +598,7 @@ CIFS_SessSetup(unsigned int xid, struct cifs_ses *ses, struct key *spnego_key = NULL; __le32 phase = NtLmNegotiate; /* NTLMSSP, if needed, is multistage */ u16 blob_len; - char *ntlmsspblob = NULL; + unsigned char *ntlmsspblob = NULL; if (ses == NULL) return -EINVAL; @@ -832,21 +852,7 @@ ssetup_ntlmssp_authenticate: cpu_to_le16(sizeof(NEGOTIATE_MESSAGE)); break; case NtLmAuthenticate: - /* - * 5 is an empirical value, large enough to hold - * authenticate message plus max 10 of av paris, - * domain, user, workstation names, flags, etc. - */ - ntlmsspblob = kzalloc( - 5*sizeof(struct _AUTHENTICATE_MESSAGE), - GFP_KERNEL); - if (!ntlmsspblob) { - cERROR(1, "Can't allocate NTLMSSP blob"); - rc = -ENOMEM; - goto ssetup_exit; - } - - rc = build_ntlmssp_auth_blob(ntlmsspblob, + rc = build_ntlmssp_auth_blob(&ntlmsspblob, &blob_len, ses, nls_cp); if (rc) goto ssetup_exit; -- 2.30.2