Add support for duplicate allow rule detection (-D / --dups).

Usage:
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.

Also add a tools/README with a description of all of the tools.

Change-Id: I07838dbd22c5cc8a4a65b57003ccae38129050f5
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>

1 files changed, 83 insertions, 0 deletions

diff --git a/tools/README b/tools/README
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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.
+
+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.