[PATCH 3.2 84/94] cifs: dynamic allocation of ntlmssp blob
From: Ben Hutchings
Date: Sun Aug 14 2016 - 14:01:50 EST
3.2.82-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Jerome Marchand <jmarchan@xxxxxxxxxx>
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 <jmarchan@xxxxxxxxxx>
Signed-off-by: Steve French <smfrench@xxxxxxxxx>
[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 <ben@xxxxxxxxxxxxxxx>
---
--- a/fs/cifs/sess.c
+++ b/fs/cifs/sess.c
@@ -444,19 +444,43 @@ static void build_ntlmssp_negotiate_blob
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(unsig
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(unsig
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(unsig
}
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(unsig
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(unsig
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(unsig
(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
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;