1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
|
-- Session handling routines - written for acf
-- Copyright (C) 2007 N. Angelacos - GPL2 License
--[[ Note that in this library, we use empty (0 byte) files
-- everwhere we can, as they only take up dir entries, not inodes
-- as the tmpfs blocksize is 4K, and under denial of service
-- attacks hundreds or thousands of events can come in each
-- second, we could end up in a disk full condition if we did
-- not take this precaution.
-- ]]--
local mymodule = {}
posix = require("posix")
minutes_expired_events=30
minutes_count_events=30
limit_count_events=10
cached_content=nil
local b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_-"
-- Return a sessionid of at least size bits length
mymodule.random_hash = function (size)
local file = io.open("/dev/urandom")
local str = ""
if file == nil then return nil end
while (size > 0 ) do
local offset = (string.byte(file:read(1)) % 64) + 1
str = str .. string.sub (b64, offset, offset)
size = size - 6
end
return str
end
-- FIXME: only hashes ipv4
mymodule.hash_ip_addr = function (ip)
local str = ""
for i in string.gmatch(ip or "", "%d+") do
str = str .. string.format("%02x", i )
end
return str
end
mymodule.ip_addr_from_hash = function (hash)
local str = ""
for i in string.gmatch(hash or "", "..") do
str = str .. string.format("%d", "0x" .. i) .. "."
end
return string.sub(str, 1, string.len(str)-1)
end
--[[
These functions serialize a table, including nested tables.
The code based on code in PiL 2nd edition p113
]]--
local function basicSerialize (o)
if type(o) == "number" then
return tostring(o)
else
return string.format("%q", o)
end
end
mymodule.serialize = function(name, value, saved, output )
local need_to_concat = (output == nil)
output = output or {}
saved = saved or {}
local str = name .. " = "
if type(value) == "number" or type(value) == "string" then
table.insert(output, str .. basicSerialize (value))
elseif type(value) == "table" then
if saved[value] then
table.insert(output, str .. saved[value])
else
saved[value] = name
table.insert(output, str .. "{}")
for k,v in pairs(value) do
local fieldname = string.format("%s[%s]", name, basicSerialize(k))
mymodule.serialize (fieldname, v, saved, output)
end
end
elseif type(value) == "boolean" then
table.insert(output, str .. tostring(value))
else
table.insert(output, str .. "nil") -- cannot save other types, so skip them
end
if need_to_concat then
table.sort(output)
return table.concat(output, "\n")
end
return
end
-- Save the session (unless all it contains is the id)
-- return true or false for success
mymodule.save_session = function( sessionpath, sessiontable)
if nil == sessiontable or nil == sessiontable.id then return false end
-- clear the id key, don't need to store that
local id = sessiontable.id
sessiontable.id = nil
-- If the table only has an "id" field, then don't save it
if #sessiontable then
local output = {}
output[#output+1] = "-- This is an ACF session table."
output[#output+1] = "local " .. mymodule.serialize("s", sessiontable)
output[#output+1] = "return s"
local content = table.concat(output, "\n") .. "\n"
-- want to avoid writing unless changed, becuase opening for write
-- prevents simultaneous opening for read
if content ~= cached_content then
local file = io.open(sessionpath .. "/session." .. id , "w")
if file == nil then
sessiontable.id=id
return false
end
file:write(content)
file:close()
end
end
sessiontable.id=id
return true
end
-- Loads a session
-- Returns a timestamp (when the session data was saved) and the session table.
-- Insert the session into the "id" field
mymodule.load_session = function ( sessionpath, session )
if type(session) ~= "string" then return nil, {} end
local s = {}
-- session can only have b64 characters in it
session = string.gsub ( session or "", "[^" .. b64 .. "]", "")
if #session == 0 then
return nil, {}
end
local spath = sessionpath .. "/session." .. session
local ts = posix.stat(spath, "ctime")
if (ts) then
-- this loop is here because can't read file here if another process is writing it above
-- and if this fails, it effectively logs the user off (writes back blank session data)
local s
for i=1,20 do
local file = io.open(spath)
if file then
cached_content = file:read("*a")
file:close()
s = loadstring(cached_content)()
break
end
sleep(10*i)
end
s = s or {}
s.id = session
return ts, s
else
return nil, {}
end
end
-- Unlinks a session (deletes the session file)
-- return nil for failure, ?? for success
mymodule.unlink_session = function (sessionpath, session)
if type(session) ~= "string" then return nil end
local s = string.gsub (session, "[^" .. b64 .. "]", "")
if s ~= session then
return nil
end
session = sessionpath .. "/session." .. s
local statos = os.remove (session)
return statos
end
-- Record an invalid logon event
-- ID would typically be an ip address or username
-- the format is lockevent.id.datetime.processid
mymodule.record_event = function( sessionpath, id_u, id_ip )
local x = io.open (string.format ("%s/lockevent.%s.%s.%s.%s",
sessionpath or "/", id_u or "", mymodule.hash_ip_addr(id_ip), os.time(),
(posix.getpid("pid")) or "" ), "w")
io.close(x)
end
-- List invalid logon events
-- Can specify username and/or ip address to filter
mymodule.list_events = function (sessionpath, id_user, ipaddr, minutes)
local list = {}
local now = os.time()
local minutes_ago = now - ((minutes or minutes_count_events) * 60)
local t = {}
--give me all lockevents then we will sort through them
local searchfor = sessionpath .. "/lockevent.*"
local t = posix.glob(searchfor)
local ipaddrhash = mymodule.hash_ip_addr(ipaddr)
for a,b in pairs(t or {}) do
if posix.stat(b,"mtime") > minutes_ago then
local user, ip, time, pid = string.match(b, "/lockevent%.([^.]*)%.([^.]*)%.([^.]*)%.([^.]*)$")
if user and (not id_user or id_user == user) and (not ipaddr or ipaddrhash == ip) then
list[#list+1] = {userid=user, ip=mymodule.ip_addr_from_hash(ip), time=time, pid=pid}
end
end
end
return list
end
-- Check how many invalid logon events
-- have happened for this id in the last n minutes
mymodule.count_events = function (sessionpath, id_user, ipaddr, minutes, limit)
local locked = false
local list = mymodule.list_events(sessionpath, id_user, ipaddr, minutes)
if #list>(tonumber(limit) or limit_count_events) then
locked = true
else
locked = false
end
return locked
end
-- Clear events that are older than n minutes
mymodule.expired_events = function (sessionpath, minutes)
--current os time in seconds
local now = os.time()
--take minutes and convert to seconds
local minutes_ago = now - ((minutes or minutes_expired_events) * 60)
local searchfor = sessionpath .. "/lockevent.*"
--first do the lockevent files
local temp = posix.glob(searchfor)
if temp ~= nil then
for a,b in pairs(temp) do
if posix.stat(b,"mtime") < minutes_ago then
os.remove(b)
end
end
end
--now do the session files
searchfor = sessionpath .. "/session.*"
local temp = posix.glob(searchfor)
if temp ~= nil then
for a,b in pairs(temp) do
if posix.stat(b,"mtime") < minutes_ago then
os.remove(b)
end
end
end
return 0
end
mymodule.delete_events = function (sessionpath, id_user, ipaddr)
--give me all lockevents then we will sort through them
local searchfor = sessionpath .. "/lockevent.*"
local t = posix.glob(searchfor)
local ipaddrhash = mymodule.hash_ip_addr(ipaddr)
for a,b in pairs(t or {}) do
local user, ip = string.match(b, "/lockevent%.([^.]*)%.([^.]*)%.")
if user and (not id_user or id_user == user) and (not ipaddr or ipaddrhash == ip) then
os.remove(b)
end
end
end
return mymodule
|