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This directory contains a number of tools related to policy, some of
which are used in building and validating the policy and others are
available for help in auditing and analyzing policy. The tools are
described further below.
checkfc
A utility for checking the validity of a file_contexts or a
property_contexts configuration file. Used as part of the policy
build to validate both files. Requires the sepolicy file as an
argument in order to check the validity of the security contexts
in the file_contexts or property_contexts file.
Usage:
checkfc sepolicy file_contexts
checkfc -p sepolicy property_contexts
checkseapp
A utility for merging together the main seapp_contexts
configuration and the device-specific one, and simultaneously
checking the validity of the configurations. Used as part of the
policy build process to merge and validate the configuration.
Usage:
checkseapp -p sepolicy input_seapp_contexts0 [input_seapp_contexts1...] -o seapp_contexts
insertkeys.py
A helper script for mapping tags in the signature stanzas of
mac_permissions.xml to public keys found in pem files. This
script is described further in the top-level sepolicy/README.
post_process_mac_perms
A tool to help modify an existing mac_permissions.xml with additional app
certs not already found in that policy. This becomes useful when a directory
containing apps is searched and the certs from those apps are added to the
policy not already explicitly listed.
Usage:
post_process_mac_perms [-h] -s SEINFO -d DIR -f POLICY
-s SEINFO, --seinfo SEINFO seinfo tag for each generated stanza
-d DIR, --dir DIR Directory to search for apks
-f POLICY, --file POLICY mac_permissions.xml policy file
sepolicy-check
A tool for auditing a sepolicy file for any allow rule that grants
a given permission.
Usage:
sepolicy-check -s <domain> -t <type> -c <class> -p <permission> -P out/target/product/<board>/root/sepolicy
sepolicy-analyze
A tool for performing various kinds of analysis on a sepolicy
file. The current kinds of analysis that are currently supported
include:
TYPE EQUIVALENCE
sepolicy-analyze -e -P out/target/product/<board>/root/sepolicy
Display all type pairs that are "equivalent", i.e. they are
identical with respect to allow rules, including indirect allow
rules via attributes and default-enabled conditional rules
(i.e. default boolean values yield a true conditional expression).
Equivalent types are candidates for being coalesced into a single
type. However, there may be legitimate reasons for them to remain
separate, for example: - the types may differ in a respect not
included in the current analysis, such as default-disabled
conditional rules, audit-related rules (auditallow or dontaudit),
default type transitions, or constraints (e.g. mls), or - the
current policy may be overly permissive with respect to one or the
other of the types and thus the correct action may be to tighten
access to one or the other rather than coalescing them together,
or - the domains that would in fact have different accesses to the
types may not yet be defined or may be unconfined in the policy
you are analyzing.
TYPE DIFFERENCE
sepolicy-analyze -d -P out/target/product/<board>/root/sepolicy
Display type pairs that differ and the first difference found
between the two types. This may be used in looking for similar
types that are not equivalent but may be candidates for coalescing.
DUPLICATE ALLOW RULES
sepolicy-analyze -D -P out/target/product/<board>/root/sepolicy
Displays duplicate allow rules, i.e. pairs of allow rules that
grant the same permissions where one allow rule is written
directly in terms of individual types and the other is written in
terms of attributes associated with those same types. The rule
with individual types is a candidate for removal. The rule with
individual types may be directly represented in the source policy
or may be a result of expansion of a type negation (e.g. domain
-foo -bar is expanded to individual allow rules by the policy
compiler). Domains with unconfineddomain will typically have such
duplicate rules as a natural side effect and can be ignored.
PERMISSIVE DOMAINS
sepolicy-analyze -p -P out/target/product/<board>/root/sepolicy
Displays domains in the policy that are permissive, i.e. avc
denials are logged but not enforced for these domains. While
permissive domains can be helpful during development, they
should not be present in a final -user build.
NEVERALLOW CHECKING
sepolicy-analyze [-w] [-z] -n neverallows.conf -P out/target/product/<board>/root/sepolicy
Check whether the sepolicy file violates any of the neverallow rules
from neverallows.conf. neverallows.conf is a file containing neverallow
statements in the same format as the SELinux policy.conf file, i.e. after
m4 macro expansion of the rules from a .te file. You can use an entire
policy.conf file as the neverallows.conf file and sepolicy-analyze will
ignore everything except for the neverallows within it. If there are
no violations, sepolicy-analyze will exit successfully with no output.
Otherwise, sepolicy-analyze will report all violations and exit
with a non-zero exit status.
The -w or --warn option may be used to warn on any types, attributes,
classes, or permissions from a neverallow rule that could not be resolved
within the sepolicy file. This can be normal due to differences between
the policy from which the neverallow rules were taken and the policy
being checked. Such values are ignored for the purposes of neverallow
checking.
The -z (-d was already taken!) or --debug option may be used to cause
sepolicy-analyze to emit the neverallow rules as it parses them from
the neverallows.conf file. This is principally a debugging facility
for the parser but could also be used to extract neverallow rules from
a full policy.conf file and output them in a more easily parsed format.
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