diff options
| -rw-r--r-- | changelog.d/5133.bugfix | 1 | ||||
| -rw-r--r-- | changelog.d/5134.bugfix | 1 | ||||
| -rw-r--r-- | docs/sample_config.yaml | 17 | ||||
| -rw-r--r-- | synapse/config/repository.py | 31 | ||||
| -rw-r--r-- | synapse/util/stringutils.py | 9 |
5 files changed, 42 insertions, 17 deletions
diff --git a/changelog.d/5133.bugfix b/changelog.d/5133.bugfix new file mode 100644 index 0000000000..be6474a692 --- /dev/null +++ b/changelog.d/5133.bugfix @@ -0,0 +1 @@ +Switch to using a cryptographically-secure random number generator for token strings, ensuring they cannot be predicted by an attacker. Thanks to @opnsec for identifying and responsibly disclosing this issue! diff --git a/changelog.d/5134.bugfix b/changelog.d/5134.bugfix new file mode 100644 index 0000000000..684d48c53a --- /dev/null +++ b/changelog.d/5134.bugfix @@ -0,0 +1 @@ +Blacklist 0.0.0.0 and :: by default for URL previews. Thanks to @opnsec for identifying and responsibly disclosing this issue too! diff --git a/docs/sample_config.yaml b/docs/sample_config.yaml index fa2bccd5ef..84337a7c72 100644 --- a/docs/sample_config.yaml +++ b/docs/sample_config.yaml @@ -548,11 +548,12 @@ uploads_path: "DATADIR/uploads" # height: 600 # method: scale -# Is the preview URL API enabled? If enabled, you *must* specify -# an explicit url_preview_ip_range_blacklist of IPs that the spider is -# denied from accessing. +# Is the preview URL API enabled? # -#url_preview_enabled: false +# 'false' by default: uncomment the following to enable it (and specify a +# url_preview_ip_range_blacklist blacklist). +# +#url_preview_enabled: true # List of IP address CIDR ranges that the URL preview spider is denied # from accessing. There are no defaults: you must explicitly @@ -562,6 +563,12 @@ uploads_path: "DATADIR/uploads" # synapse to issue arbitrary GET requests to your internal services, # causing serious security issues. # +# (0.0.0.0 and :: are always blacklisted, whether or not they are explicitly +# listed here, since they correspond to unroutable addresses.) +# +# This must be specified if url_preview_enabled is set. It is recommended that +# you uncomment the following list as a starting point. +# #url_preview_ip_range_blacklist: # - '127.0.0.0/8' # - '10.0.0.0/8' @@ -572,7 +579,7 @@ uploads_path: "DATADIR/uploads" # - '::1/128' # - 'fe80::/64' # - 'fc00::/7' -# + # List of IP address CIDR ranges that the URL preview spider is allowed # to access even if they are specified in url_preview_ip_range_blacklist. # This is useful for specifying exceptions to wide-ranging blacklisted diff --git a/synapse/config/repository.py b/synapse/config/repository.py index 3f34ad9b2a..fbfcecc240 100644 --- a/synapse/config/repository.py +++ b/synapse/config/repository.py @@ -186,17 +186,21 @@ class ContentRepositoryConfig(Config): except ImportError: raise ConfigError(MISSING_NETADDR) - if "url_preview_ip_range_blacklist" in config: - self.url_preview_ip_range_blacklist = IPSet( - config["url_preview_ip_range_blacklist"] - ) - else: + if "url_preview_ip_range_blacklist" not in config: raise ConfigError( "For security, you must specify an explicit target IP address " "blacklist in url_preview_ip_range_blacklist for url previewing " "to work" ) + self.url_preview_ip_range_blacklist = IPSet( + config["url_preview_ip_range_blacklist"] + ) + + # we always blacklist '0.0.0.0' and '::', which are supposed to be + # unroutable addresses. + self.url_preview_ip_range_blacklist.update(['0.0.0.0', '::']) + self.url_preview_ip_range_whitelist = IPSet( config.get("url_preview_ip_range_whitelist", ()) ) @@ -260,11 +264,12 @@ class ContentRepositoryConfig(Config): #thumbnail_sizes: %(formatted_thumbnail_sizes)s - # Is the preview URL API enabled? If enabled, you *must* specify - # an explicit url_preview_ip_range_blacklist of IPs that the spider is - # denied from accessing. + # Is the preview URL API enabled? + # + # 'false' by default: uncomment the following to enable it (and specify a + # url_preview_ip_range_blacklist blacklist). # - #url_preview_enabled: false + #url_preview_enabled: true # List of IP address CIDR ranges that the URL preview spider is denied # from accessing. There are no defaults: you must explicitly @@ -274,6 +279,12 @@ class ContentRepositoryConfig(Config): # synapse to issue arbitrary GET requests to your internal services, # causing serious security issues. # + # (0.0.0.0 and :: are always blacklisted, whether or not they are explicitly + # listed here, since they correspond to unroutable addresses.) + # + # This must be specified if url_preview_enabled is set. It is recommended that + # you uncomment the following list as a starting point. + # #url_preview_ip_range_blacklist: # - '127.0.0.0/8' # - '10.0.0.0/8' @@ -284,7 +295,7 @@ class ContentRepositoryConfig(Config): # - '::1/128' # - 'fe80::/64' # - 'fc00::/7' - # + # List of IP address CIDR ranges that the URL preview spider is allowed # to access even if they are specified in url_preview_ip_range_blacklist. # This is useful for specifying exceptions to wide-ranging blacklisted diff --git a/synapse/util/stringutils.py b/synapse/util/stringutils.py index fdcb375f95..69dffd8244 100644 --- a/synapse/util/stringutils.py +++ b/synapse/util/stringutils.py @@ -24,14 +24,19 @@ _string_with_symbols = ( string.digits + string.ascii_letters + ".,;:^&*-_+=#~@" ) +# random_string and random_string_with_symbols are used for a range of things, +# some cryptographically important, some less so. We use SystemRandom to make sure +# we get cryptographically-secure randoms. +rand = random.SystemRandom() + def random_string(length): - return ''.join(random.choice(string.ascii_letters) for _ in range(length)) + return ''.join(rand.choice(string.ascii_letters) for _ in range(length)) def random_string_with_symbols(length): return ''.join( - random.choice(_string_with_symbols) for _ in range(length) + rand.choice(_string_with_symbols) for _ in range(length) ) |