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Message-Id: <1464256345-26131-2-git-send-email-jmarchan@redhat.com>
Date: Thu, 26 May 2016 11:52:25 +0200
From: "Jerome Marchand" <jmarchan@...hat.com>
To: Steve French <sfrench@...ba.org>
Cc: linux-cifs@...r.kernel.org, samba-technical@...ts.samba.org,
linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] 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@...hat.com>
---
fs/cifs/ntlmssp.h | 2 +-
fs/cifs/sess.c | 76 ++++++++++++++++++++++++++++++-------------------------
fs/cifs/smb2pdu.c | 10 ++------
3 files changed, 45 insertions(+), 43 deletions(-)
diff --git a/fs/cifs/ntlmssp.h b/fs/cifs/ntlmssp.h
index 848249f..3079b38 100644
--- a/fs/cifs/ntlmssp.h
+++ b/fs/cifs/ntlmssp.h
@@ -133,6 +133,6 @@ typedef struct _AUTHENTICATE_MESSAGE {
int decode_ntlmssp_challenge(char *bcc_ptr, int blob_len, struct cifs_ses *ses);
void build_ntlmssp_negotiate_blob(unsigned char *pbuffer, struct cifs_ses *ses);
-int build_ntlmssp_auth_blob(unsigned char *pbuffer, u16 *buflen,
+int build_ntlmssp_auth_blob(unsigned char **pbuffer, u16 *buflen,
struct cifs_ses *ses,
const struct nls_table *nls_cp);
diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
index c3d086e..463bed7 100644
--- a/fs/cifs/sess.c
+++ b/fs/cifs/sess.c
@@ -364,19 +364,43 @@ 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 */
-int build_ntlmssp_auth_blob(unsigned char *pbuffer,
+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, CIFS_MAX_USERNAME_LEN);
+ else
+ sz += 2;
+
+ return sz;
+}
+
+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) {
+ cifs_dbg(VFS, "Error %d during NTLMSSP authentication\n", 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;
@@ -391,7 +415,7 @@ 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 =
@@ -399,13 +423,9 @@ 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) {
- cifs_dbg(VFS, "Error %d during NTLMSSP authentication\n", 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;
@@ -423,7 +443,7 @@ 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;
@@ -432,14 +452,14 @@ int build_ntlmssp_auth_blob(unsigned char *pbuffer,
len = cifs_strtoUTF16((__le16 *)tmp, ses->domainName,
CIFS_MAX_DOMAINNAME_LEN, 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;
@@ -448,13 +468,13 @@ int build_ntlmssp_auth_blob(unsigned char *pbuffer,
len = cifs_strtoUTF16((__le16 *)tmp, ses->user_name,
CIFS_MAX_USERNAME_LEN, 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;
@@ -463,19 +483,19 @@ 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;
}
@@ -1266,7 +1286,7 @@ sess_auth_rawntlmssp_authenticate(struct sess_data *sess_data)
struct cifs_ses *ses = sess_data->ses;
__u16 bytes_remaining;
char *bcc_ptr;
- char *ntlmsspblob = NULL;
+ unsigned char *ntlmsspblob = NULL;
u16 blob_len;
cifs_dbg(FYI, "rawntlmssp session setup authenticate phase\n");
@@ -1279,19 +1299,7 @@ sess_auth_rawntlmssp_authenticate(struct sess_data *sess_data)
/* Build security blob before we assemble the request */
pSMB = (SESSION_SETUP_ANDX *)sess_data->iov[0].iov_base;
smb_buf = (struct smb_hdr *)pSMB;
- /*
- * 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) {
- rc = -ENOMEM;
- goto out;
- }
-
- rc = build_ntlmssp_auth_blob(ntlmsspblob,
+ rc = build_ntlmssp_auth_blob(&ntlmsspblob,
&blob_len, ses, sess_data->nls_cp);
if (rc)
goto out_free_ntlmsspblob;
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 8f38e33..c3e61a7 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -588,7 +588,7 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
u16 blob_length = 0;
struct key *spnego_key = NULL;
char *security_blob = NULL;
- char *ntlmssp_blob = NULL;
+ unsigned char *ntlmssp_blob = NULL;
bool use_spnego = false; /* else use raw ntlmssp */
cifs_dbg(FYI, "Session Setup\n");
@@ -713,13 +713,7 @@ ssetup_ntlmssp_authenticate:
iov[1].iov_len = blob_length;
} else if (phase == NtLmAuthenticate) {
req->hdr.SessionId = ses->Suid;
- ntlmssp_blob = kzalloc(sizeof(struct _NEGOTIATE_MESSAGE) + 500,
- GFP_KERNEL);
- if (ntlmssp_blob == NULL) {
- rc = -ENOMEM;
- goto ssetup_exit;
- }
- rc = build_ntlmssp_auth_blob(ntlmssp_blob, &blob_length, ses,
+ rc = build_ntlmssp_auth_blob(&ntlmssp_blob, &blob_length, ses,
nls_cp);
if (rc) {
cifs_dbg(FYI, "build_ntlmssp_auth_blob failed %d\n",
--
2.5.5
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