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Date: Thu, 7 Nov 2013 16:40:57 -0700
From: Tim Gardner <tim.gardner@...onical.com>
To: linux-cifs@...r.kernel.org, samba-technical@...ts.samba.org,
linux-kernel@...r.kernel.org
Cc: Tim Gardner <tim.gardner@...onical.com>,
Jeff Layton <jlayton@...hat.com>,
Steve French <sfrench@...ba.org>
Subject: [PATCH linux-next] cifs: Use data structures to compute NTLMv2 response offsets
A bit of cleanup plus some gratuitous variable renaming. I think using
structures instead of numeric offsets makes this code much more
understandable.
Also added a comment about current time range expected by
the server.
Cc: Jeff Layton <jlayton@...hat.com>
Cc: Steve French <sfrench@...ba.org>
Signed-off-by: Tim Gardner <tim.gardner@...onical.com>
---
The comment about time of day needing to be within 5 minutes is important (to me
at least). I spent the best part of a week thinking I had endian issues on powerpc
when in truth I was just too stupid to notice that the clock
was not updated. Danged embedded platforms...
checkpatch has some problems with this patch regarding attribute packed, but I chose
to remain consistent with existing code.
WARNING: __packed is preferred over __attribute__((packed))
#141: FILE: fs/cifs/cifspdu.h:705:
+ } __attribute__((packed)) challenge;
WARNING: __packed is preferred over __attribute__((packed))
#142: FILE: fs/cifs/cifspdu.h:706:
+ } __attribute__((packed));
total: 0 errors, 2 warnings, 99 lines checked
Tested on cifs-2.6 for-linus (c481e9feee78c6ce1ba0a1c8c892049f6514f6cf) by mounting
to iOS 10.8 and Win 8.0 Pro.
rtg
fs/cifs/cifsencrypt.c | 40 ++++++++++++++++++++++++----------------
fs/cifs/cifspdu.h | 8 +++++++-
2 files changed, 31 insertions(+), 17 deletions(-)
diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
index fc6f4f3..4934347 100644
--- a/fs/cifs/cifsencrypt.c
+++ b/fs/cifs/cifsencrypt.c
@@ -548,7 +548,13 @@ static int
CalcNTLMv2_response(const struct cifs_ses *ses, char *ntlmv2_hash)
{
int rc;
- unsigned int offset = CIFS_SESS_KEY_SIZE + 8;
+ struct ntlmv2_resp *ntlmv2 = (struct ntlmv2_resp *)
+ (ses->auth_key.response + CIFS_SESS_KEY_SIZE);
+ unsigned int hash_len;
+
+ /* The MD5 hash starts at challenge_key.key */
+ hash_len = ses->auth_key.len - (CIFS_SESS_KEY_SIZE +
+ offsetof(struct ntlmv2_resp, challenge.key[0]));
if (!ses->server->secmech.sdeschmacmd5) {
cifs_dbg(VFS, "%s: can't generate ntlmv2 hash\n", __func__);
@@ -556,7 +562,7 @@ CalcNTLMv2_response(const struct cifs_ses *ses, char *ntlmv2_hash)
}
rc = crypto_shash_setkey(ses->server->secmech.hmacmd5,
- ntlmv2_hash, CIFS_HMAC_MD5_HASH_SIZE);
+ ntlmv2_hash, CIFS_HMAC_MD5_HASH_SIZE);
if (rc) {
cifs_dbg(VFS, "%s: Could not set NTLMV2 Hash as a key\n",
__func__);
@@ -570,20 +576,21 @@ CalcNTLMv2_response(const struct cifs_ses *ses, char *ntlmv2_hash)
}
if (ses->server->negflavor == CIFS_NEGFLAVOR_EXTENDED)
- memcpy(ses->auth_key.response + offset,
- ses->ntlmssp->cryptkey, CIFS_SERVER_CHALLENGE_SIZE);
+ memcpy(ntlmv2->challenge.key,
+ ses->ntlmssp->cryptkey, CIFS_SERVER_CHALLENGE_SIZE);
else
- memcpy(ses->auth_key.response + offset,
- ses->server->cryptkey, CIFS_SERVER_CHALLENGE_SIZE);
+ memcpy(ntlmv2->challenge.key,
+ ses->server->cryptkey, CIFS_SERVER_CHALLENGE_SIZE);
rc = crypto_shash_update(&ses->server->secmech.sdeschmacmd5->shash,
- ses->auth_key.response + offset, ses->auth_key.len - offset);
+ ntlmv2->challenge.key, hash_len);
if (rc) {
cifs_dbg(VFS, "%s: Could not update with response\n", __func__);
return rc;
}
+ /* Note that the MD5 digest over writes anon.challenge_key.key */
rc = crypto_shash_final(&ses->server->secmech.sdeschmacmd5->shash,
- ses->auth_key.response + CIFS_SESS_KEY_SIZE);
+ ntlmv2->ntlmv2_hash);
if (rc)
cifs_dbg(VFS, "%s: Could not generate md5 hash\n", __func__);
@@ -627,7 +634,7 @@ setup_ntlmv2_rsp(struct cifs_ses *ses, const struct nls_table *nls_cp)
int rc;
int baselen;
unsigned int tilen;
- struct ntlmv2_resp *buf;
+ struct ntlmv2_resp *ntlmv2;
char ntlmv2_hash[16];
unsigned char *tiblob = NULL; /* target info blob */
@@ -660,13 +667,14 @@ setup_ntlmv2_rsp(struct cifs_ses *ses, const struct nls_table *nls_cp)
}
ses->auth_key.len += baselen;
- buf = (struct ntlmv2_resp *)
+ ntlmv2 = (struct ntlmv2_resp *)
(ses->auth_key.response + CIFS_SESS_KEY_SIZE);
- buf->blob_signature = cpu_to_le32(0x00000101);
- buf->reserved = 0;
- buf->time = cpu_to_le64(cifs_UnixTimeToNT(CURRENT_TIME));
- get_random_bytes(&buf->client_chal, sizeof(buf->client_chal));
- buf->reserved2 = 0;
+ ntlmv2->blob_signature = cpu_to_le32(0x00000101);
+ ntlmv2->reserved = 0;
+ /* Must be within 5 minutes of the server */
+ ntlmv2->time = cpu_to_le64(cifs_UnixTimeToNT(CURRENT_TIME));
+ get_random_bytes(&ntlmv2->client_chal, sizeof(ntlmv2->client_chal));
+ ntlmv2->reserved2 = 0;
memcpy(ses->auth_key.response + baselen, tiblob, tilen);
@@ -706,7 +714,7 @@ setup_ntlmv2_rsp(struct cifs_ses *ses, const struct nls_table *nls_cp)
}
rc = crypto_shash_update(&ses->server->secmech.sdeschmacmd5->shash,
- ses->auth_key.response + CIFS_SESS_KEY_SIZE,
+ ntlmv2->ntlmv2_hash,
CIFS_HMAC_MD5_HASH_SIZE);
if (rc) {
cifs_dbg(VFS, "%s: Could not update with response\n", __func__);
diff --git a/fs/cifs/cifspdu.h b/fs/cifs/cifspdu.h
index 9e5ee34..33df36e 100644
--- a/fs/cifs/cifspdu.h
+++ b/fs/cifs/cifspdu.h
@@ -697,7 +697,13 @@ struct ntlmssp2_name {
} __attribute__((packed));
struct ntlmv2_resp {
- char ntlmv2_hash[CIFS_ENCPWD_SIZE];
+ union {
+ char ntlmv2_hash[CIFS_ENCPWD_SIZE];
+ struct {
+ __u8 reserved[8];
+ __u8 key[CIFS_SERVER_CHALLENGE_SIZE];
+ } __attribute__((packed)) challenge;
+ } __attribute__((packed));
__le32 blob_signature;
__u32 reserved;
__le64 time;
--
1.7.9.5
--
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