sepolicy-analyze
A component-ized tool for performing various kinds of analysis on a
sepolicy file. The current kinds of analysis that are currently
supported include:
TYPE EQUIVALENCE (typecmp)
sepolicy-analyze out/target/product/<board>/root/sepolicy typecmp -e
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 (typecmp)
sepolicy-analyze out/target/product/<board>/root/sepolicy typecmp -d
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 (dups)
sepolicy-analyze out/target/product/<board>/root/sepolicy dups
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 (permissive)
sepolicy-analyze out/target/product/<board>/root/sepolicy permissive
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.
BOOLEANS (booleans)
sepolicy-analyze out/target/product/<board>/root/sepolicy booleans
Displays the boolean names in the policy (if any).
Policy booleans are forbidden in Android policy, so if there is any
output, the policy will fail CTS.
ATTRIBUTE (attribute)
sepolicy-analyze out/target/product/<board>/root/sepolicy attribute <name>
Displays the types associated with the specified attribute name.
NEVERALLOW CHECKING (neverallow)
sepolicy-analyze out/target/product/<board>/root/sepolicy neverallow \
[-w] [-d] [-f neverallows.conf] | [-n "neverallow string"]
Check whether the sepolicy file violates any of the neverallow rules
from the neverallows.conf file or a given string, which contain 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. You can also
specify this as a command-line string argument, which could be useful for
quickly checking an individual expanded rule or group of rules. 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 -d or --debug option may be used to cause sepolicy-analyze to emit the
neverallow rules as it parses them. 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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