aboutsummaryrefslogtreecommitdiffstats
path: root/Library/Homebrew/sandbox.rb
blob: 7d23e59664ae3f41a1ecaba323e64b4e227d3056 (plain)
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
require "erb"
require "tempfile"

class Sandbox
  SANDBOX_EXEC = "/usr/bin/sandbox-exec".freeze

  def self.available?
    OS.mac? && OS::Mac.version >= "10.6" && File.executable?(SANDBOX_EXEC)
  end

  def self.formula?(_formula)
    return false unless available?
    !ARGV.no_sandbox?
  end

  def self.test?
    return false unless available?
    !ARGV.no_sandbox?
  end

  def initialize
    @profile = SandboxProfile.new
  end

  def record_log(file)
    @logfile = file
  end

  def add_rule(rule)
    @profile.add_rule(rule)
  end

  def allow_write(path, options = {})
    add_rule allow: true, operation: "file-write*", filter: path_filter(path, options[:type])
  end

  def deny_write(path, options = {})
    add_rule allow: false, operation: "file-write*", filter: path_filter(path, options[:type])
  end

  def allow_write_path(path)
    allow_write path, type: :subpath
  end

  def deny_write_path(path)
    deny_write path, type: :subpath
  end

  def allow_write_temp_and_cache
    allow_write_path "/private/tmp"
    allow_write_path "/private/var/tmp"
    allow_write "^/private/var/folders/[^/]+/[^/]+/[C,T]/", type: :regex
    allow_write_path HOMEBREW_TEMP
    allow_write_path HOMEBREW_CACHE
  end

  def allow_write_cellar(formula)
    allow_write_path formula.rack
    allow_write_path formula.etc
    allow_write_path formula.var
  end

  # Xcode projects expect access to certain cache/archive dirs.
  def allow_write_xcode
    allow_write_path "/Users/#{ENV["USER"]}/Library/Developer"
  end

  def allow_write_log(formula)
    allow_write_path formula.logs
  end

  def deny_write_homebrew_repository
    deny_write HOMEBREW_BREW_FILE
    if HOMEBREW_PREFIX.to_s != HOMEBREW_REPOSITORY.to_s
      deny_write_path HOMEBREW_REPOSITORY
    else
      deny_write_path HOMEBREW_LIBRARY
      deny_write_path HOMEBREW_REPOSITORY/".git"
    end
  end

  def exec(*args)
    seatbelt = Tempfile.new(["homebrew", ".sb"], HOMEBREW_TEMP)
    seatbelt.write(@profile.dump)
    seatbelt.close
    @start = Time.now
    safe_system SANDBOX_EXEC, "-f", seatbelt.path, *args
  rescue
    @failed = true
    raise
  ensure
    seatbelt.unlink
    sleep 0.1 # wait for a bit to let syslog catch up the latest events.
    syslog_args = %W[
      -F $((Time)(local))\ $(Sender)[$(PID)]:\ $(Message)
      -k Time ge #{@start.to_i}
      -k Message S deny
      -k Sender kernel
      -o
      -k Time ge #{@start.to_i}
      -k Message S deny
      -k Sender sandboxd
    ]
    logs = Utils.popen_read("syslog", *syslog_args)

    # These messages are confusing and non-fatal, so don't report them.
    logs = logs.lines.reject { |l| l.match(/^.*Python\(\d+\) deny file-write.*pyc$/) }.join

    unless logs.empty?
      if @logfile
        log = open(@logfile, "w")
        log.write logs
        log.write "\nWe use time to filter sandbox log. Therefore, unrelated logs may be recorded.\n"
        log.close
      end

      if @failed && ARGV.verbose?
        ohai "Sandbox log"
        puts logs
        $stdout.flush # without it, brew test-bot would fail to catch the log
      end
    end
  end

  private

  def expand_realpath(path)
    raise unless path.absolute?
    path.exist? ? path.realpath : expand_realpath(path.parent)/path.basename
  end

  def path_filter(path, type)
    case type
    when :regex        then "regex \#\"#{path}\""
    when :subpath      then "subpath \"#{expand_realpath(Pathname.new(path))}\""
    when :literal, nil then "literal \"#{expand_realpath(Pathname.new(path))}\""
    end
  end

  class SandboxProfile
    SEATBELT_ERB = <<-EOS.undent
      (version 1)
      (debug deny) ; log all denied operations to /var/log/system.log
      <%= rules.join("\n") %>
      (allow file-write*
          (literal "/dev/ptmx")
          (literal "/dev/dtracehelper")
          (literal "/dev/null")
          (literal "/dev/random")
          (literal "/dev/zero")
          (regex #"^/dev/fd/[0-9]+$")
          (regex #"^/dev/ttys?[0-9]*$")
          )
      (deny file-write*) ; deny non-whitelist file write operations
      (allow process-exec
          (literal "/bin/ps")
          (with no-sandbox)
          ) ; allow certain processes running without sandbox
      (allow default) ; allow everything else
    EOS

    attr_reader :rules

    def initialize
      @rules = []
    end

    def add_rule(rule)
      s = "("
      s << (rule[:allow] ? "allow" : "deny")
      s << " #{rule[:operation]}"
      s << " (#{rule[:filter]})" if rule[:filter]
      s << " (with #{rule[:modifier]})" if rule[:modifier]
      s << ")"
      @rules << s
    end

    def dump
      ERB.new(SEATBELT_ERB).result(binding)
    end
  end
end