xref: /system/sepolicy/tools/sepolicy-analyze/README

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.

    sepolicy-analyze out/target/product/<board>/root/sepolicy attribute -r <name>

    Displays the attributes associated with the specified type name.

    sepolicy-analyze out/target/product/<board>/root/sepolicy attribute -l

    Displays all attributes in the policy.

    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.