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Support HMAC SHA256 in IPMI

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While SHA1 is technically secure in an HMAC, some implementations
no longer allow it by default.  Try for SHA256, and if that should
fail, fallback to SHA1 for implementations lacking support.

Change-Id: I6380e042fbe959af4059e63a5620f6289263737c
This commit is contained in:
Jarrod Johnson
2019-07-26 11:38:19 -04:00
parent f1e9ecf15c
commit eb73628360
1 changed files with 38 additions and 16 deletions
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pyghmi/ipmi/private/session.py
+38 -16
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@@ -583,6 +583,9 @@ class Session(object):
self.confalgo = 0
self.aeskey = None
self.integrityalgo = 0
self.attemptedhash = 256
self.currhashlib = None
self.currhashlen = 0
self.k1 = None
self.rmcptag = 1
self.lastpayload = None
@@ -905,7 +908,7 @@ class Session(object):
# specification followed
message += hmac.new(self.k1,
bytes(message[4:]),
hashlib.sha1).digest()[:12] # SHA1-96
self.currhashlib).digest()[:self.currhashlen]
# per RFC2404 truncates to 96 bits
self.netpacket = message
# advance idle timer since we don't need keepalive while sending
@@ -1049,13 +1052,28 @@ class Session(object):
0, 0, # reserved
])
data += struct.pack("<I", self.localsid)
data += bytearray([
0, 0, 0, 8, 1, 0, 0, 0, # table 13-17, SHA-1
1, 0, 0, 8, 1, 0, 0, 0, # SHA-1 integrity
2, 0, 0, 8, 1, 0, 0, 0, # AES privacy
# 2,0,0,8,0,0,0,0, #no privacy confalgo
])
# auth 3 sha256
# integrity... 4 = sha256
if self.attemptedhash == 1:
data += bytearray([
0, 0, 0, 8, 1, 0, 0, 0, # table 13-17, SHA-1
1, 0, 0, 8, 1, 0, 0, 0, # SHA-1 integrity
2, 0, 0, 8, 1, 0, 0, 0, # AES privacy
# 2,0,0,8,0,0,0,0, #no privacy confalgo
])
self.currhashlib = hashlib.sha1
self.currhashlen = 12
else:
data += bytearray([
0, 0, 0, 8, 3, 0, 0, 0, # table 13-17, SHA-256
1, 0, 0, 8, 4, 0, 0, 0, # SHA-256-128 integrity
2, 0, 0, 8, 1, 0, 0, 0, # AES privacy
# 2,0,0,8,0,0,0,0, #no privacy confalgo
])
self.currhashlib = hashlib.sha256
self.currhashlen = 16
self.sessioncontext = 'OPENSESSION'
self.lastpayload = None
self.send_payload(
payload=data,
payload_type=constants.payload_types['rmcpplusopenreq'])
@@ -1357,11 +1375,11 @@ class Session(object):
encrypted = 0
if data[5] & 0b10000000:
encrypted = 1
authcode = data[-12:]
authcode = data[-self.currhashlen:]
if self.k1 is None: # we are in no shape to process a packet now
return
expectedauthcode = hmac.new(
self.k1, data[4:-12], hashlib.sha1).digest()[:12]
self.k1, data[4:-self.currhashlen], self.currhashlib).digest()[:self.currhashlen]
if authcode != expectedauthcode:
return # BMC failed to assure integrity to us, drop it
sid = struct.unpack("<I", bytes(data[6:10]))[0]
@@ -1418,6 +1436,10 @@ class Session(object):
if data[0] != self.rmcptag:
return -9 # use rmcp tag to track and reject stale responses
if data[1] != 0: # response code...
if self.attemptedhash == 256:
self.attemptedhash = 1
self._open_rmcpplus_request()
return
if data[1] in constants.rmcp_codes:
errstr = constants.rmcp_codes[data[1]]
else:
@@ -1486,7 +1508,7 @@ class Session(object):
self.randombytes + self.remoterandombytes + self.remoteguid +\
struct.pack("2B", self.nameonly | self.privlevel, userlen) +\
self.userid
expectedhash = hmac.new(self.password, hmacdata, hashlib.sha1).digest()
expectedhash = hmac.new(self.password, hmacdata, self.currhashlib).digest()
hashlen = len(expectedhash)
givenhash = struct.pack("%dB" % hashlen, *data[40:hashlen + 40])
if givenhash != expectedhash:
@@ -1499,9 +1521,9 @@ class Session(object):
self.randombytes + self.remoterandombytes +
struct.pack("2B", self.nameonly | self.privlevel,
userlen) +
self.userid, hashlib.sha1).digest()
self.k1 = hmac.new(self.sik, b'\x01' * 20, hashlib.sha1).digest()
self.k2 = hmac.new(self.sik, b'\x02' * 20, hashlib.sha1).digest()
self.userid, self.currhashlib).digest()
self.k1 = hmac.new(self.sik, b'\x01' * 20, self.currhashlib).digest()
self.k2 = hmac.new(self.sik, b'\x02' * 20, self.currhashlib).digest()
self.aeskey = self.k2[0:16]
self.sessioncontext = "EXPECTINGRAKP4"
self.lastpayload = None
@@ -1518,7 +1540,7 @@ class Session(object):
len(self.userid)) +\
self.userid
authcode = hmac.new(self.password, hmacdata, hashlib.sha1).digest()
authcode = hmac.new(self.password, hmacdata, self.currhashlib).digest()
payload += list(struct.unpack("%dB" % len(authcode), authcode))
self.send_payload(
payload=payload, payload_type=constants.payload_types['rakp3'])
@@ -1554,14 +1576,14 @@ class Session(object):
struct.pack("<I", self.pendingsessionid) +\
self.remoteguid
expectedauthcode = hmac.new(self.sik, hmacdata,
hashlib.sha1).digest()[:12]
self.currhashlib).digest()[:self.currhashlen]
aclen = len(expectedauthcode)
authcode = struct.pack("%dB" % aclen, *data[8:aclen + 8])
if authcode != expectedauthcode:
self.onlogon({'error': "Invalid RAKP4 integrity code (wrong Kg?)"})
return
self.sessionid = self.pendingsessionid
self.integrityalgo = 'sha1'
self.integrityalgo = self.attemptedhash
self.confalgo = 'aes'
self.sequencenumber = 1
self.sessioncontext = 'ESTABLISHED'