Commit Graph

3144 Commits

Author SHA1 Message Date
Nicolas Iooss
0744fa4f53
libsepol: use checked arithmetic builtin to perform safe addition
Checking whether an overflow occurred after adding two values can be
achieved using checked arithmetic builtin functions such as:

    bool __builtin_add_overflow(type1 x, type2 y, type3 *sum);

This function is available at least in clang
(at least since clang 3.8.0,
https://releases.llvm.org/3.8.0/tools/clang/docs/LanguageExtensions.html#checked-arithmetic-builtins)
and gcc
(https://gcc.gnu.org/onlinedocs/gcc/Integer-Overflow-Builtins.html,
since gcc 5 according to https://gcc.gnu.org/gcc-5/changes.html)

Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
2021-04-30 21:09:36 +02:00
Nicolas Iooss
f63263c2d0
libselinux: do not duplicate make target when going into subdirectory
When running "make install-pywrap", make displays:

    make[1]: Entering directory '/root/selinux/libselinux'
    make -C src install-pywrap install-pywrap
    make[2]: Entering directory '/root/selinux/libselinux/src'

The duplicated "install-pywrap" is not expected. Remove it from the
Makefile.

Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
2021-04-30 21:09:22 +02:00
James Carter
d0a07a7f13
secilc: Create the new program called secil2tree to write out CIL AST
secil2tree is the SELinux CIL AST writer. It calls the cil functions
cil_write_parse_ast(), cil_write_build_ast(), or cil_write_resolve_ast()
to write out the parse tree, the CIL AST after the build phase, or the
CIL AST after the resolve phase.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-21 21:45:31 +02:00
James Carter
86ec04cfde
libsepol/cil: Add functions to make use of cil_write_ast()
Add the functions cil_write_parse_ast(), cil_write_build_ast(),
and cil_write_resolve_ast() that can be used outside of libsepol.

These functions take a FILE pointer and CIL db, do the CIL build
through the desired phase, and then call cil_write_ast() to write
the CIL AST at that point.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-21 21:45:22 +02:00
James Carter
0b31424ac7
libsepol/cil: Create functions to write the CIL AST
The function cil_print_tree() has existed in cil_tree.c since the
beginning of the development of CIL and secilc. Unfortunately, it
used cil_log() at log level CIL_INFO to print out the AST and
has suffered greatly from bit rot.

Move the functions to write the CIL AST to cil_write_ast.c, update
the functions, and write the AST to the FILE pointer passed in as
an argument.

The function cil_write_ast() supports writing the CIL AST at three
different phases of the compiling a CIL policy. After parsing has
been done and the parse tree has been created, after the CIL AST
has been built, and after the CIL AST has been resolved.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-21 21:45:14 +02:00
Ondrej Mosnacek
6cfebe787e
policycoreutils/setfiles: do not create useless setfiles.8.man file
Seems to have been there to allow for some sed substitution over the
text. Now that this is gone, the redundant intermediate file can be
removed, too.

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
2021-04-20 09:02:52 +02:00
James Carter
bad0a746e9 secilc/docs: Update the CIL documentation for various blocks
Update the documentation for macros, booleans, booleanifs, tunables,
tunableifs, blocks, blockabstracts, blockinherits, and optionals to
tell where these statements can be used and, for those that have
blocks, what statements are not allowed in them.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 14:05:23 -04:00
James Carter
8314076cd9 libsepol/cil: Use CIL_ERR for error messages in cil_compile()
In cil_compile(), CIL_INFO is being used as the priority for
error messages. This can make it difficult to tell when the error
occurred.

Instead, use CIL_ERR as the priority for the error messages in
cil_compile().

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 14:05:21 -04:00
James Carter
ca339eb49d libsepol/cil: Make invalid statement error messages consistent
Use a consistent style for the error messages when an invalid
statement is found within tunableif, in-statement, block, macro,
optional, and booleanif blocks.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 14:05:20 -04:00
James Carter
ea34dbf041 libsepol/cil: Do not allow tunable declarations in in-statements
Since tunableifs are resolved before in-statements, do not allow
tuanble declarations in in-statements.

Since in-statements are the first flavor of statement that causes
part of the AST to be copied to another part, there is no need to
check the in-statements when resolving the AST.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 14:05:18 -04:00
James Carter
f38b7ea300 libsepol/cil: Sync checks for invalid rules in macros
When resolving the AST, tunable and in-statements are not considered
to be invalid in macros. This is inconsistent with the checks when
building the AST.

Add checks to make tunable and in-statments invalid in macros when
resolving the AST.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 14:05:16 -04:00
James Carter
340f0eb7f3 libsepol/cil: Check for statements not allowed in optional blocks
While there are some checks for invalid statements in an optional
block when resolving the AST, there are no checks when building the
AST.

OSS-Fuzz found the following policy which caused a null dereference
in cil_tree_get_next_path().
  (blockinherit b3)
  (sid SID)
  (sidorder(SID))
  (optional o
    (ibpkeycon :(1 0)s)
    (block b3
      (filecon""block())
      (filecon""block())))

The problem is that the blockinherit copies block b3 before
the optional block is disabled. When the optional is disabled,
block b3 is deleted along with everything else in the optional.
Later, when filecon statements with the same path are found an
error message is produced and in trying to find out where the block
was copied from, the reference to the deleted block is used. The
error handling code assumes (rightly) that if something was copied
from a block then that block should still exist.

It is clear that in-statements, blocks, and macros cannot be in an
optional, because that allows nodes to be copied from the optional
block to somewhere outside even though the optional could be disabled
later. When optionals are disabled the AST is reset and the
resolution is restarted at the point of resolving macro calls, so
anything resolved before macro calls will never be re-resolved.
This includes tunableifs, in-statements, blockinherits,
blockabstracts, and macro definitions. Tunable declarations also
cannot be in an optional block because they are needed to resolve
tunableifs. It should be fine to allow blockinherit statements in
an optional, because that is copying nodes from outside the optional
to the optional and if the optional is later disabled, everything
will be deleted anyway.

Check and quit with an error if a tunable declaration, in-statement,
block, blockabstract, or macro definition is found within an
optional when either building or resolving the AST.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 14:05:14 -04:00
James Carter
8a74c05b97 libsepol/cil: Sync checks for invalid rules in booleanifs
When building the AST, typemember rules in a booleanif block will
be incorrectly called invalid. They are allowed in the kernel
policy and should be allowed in CIL.

When resolving the AST, if a neverallow rule is copied into a
booleanif block, it will not be considered an invalid rule, even
though this is not allowed in the kernel policy.

Update the booleanif checks to allow typemember rules and to not
allow neverallow rules in booleanifs. Also use the same form of
conditional for the checks when building and resolving the AST.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 14:05:13 -04:00
James Carter
ef533c8fd9 libsepol/cil: Reorder checks for invalid rules when resolving AST
Reorder checks for invalid rules in the blocks of tunableifs,
in-statements, macros, and booleanifs when resolving the AST for
consistency.

Order the checks in the same order the blocks will be resolved in,
so tuanbleif, in-statement, macro, booleanif, and then non-block
rules.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 14:05:11 -04:00
James Carter
525f0312d5 libsepol/cil: Use AST to track blocks and optionals when resolving
When resolving the AST, block and optional stacks are used to
determine if the current rule being resolved is in a block or
an optional. There is no need to do this since the parent node
pointers can be used when exiting a block or an optional to
determine if resolution is still within a block or an optional.

When entering either a block or an optional, update the appropriate
tree node pointer. When finished with the last child of a block or
optional, set the appropriate pointer to NULL. If a parent of the
same kind is found when the parent node pointers are followed back
to the root node, then set the pointer to that tree node.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 14:05:09 -04:00
James Carter
ab90cb46ab libsepol/cil: Create new first child helper function for building AST
In order to find statements not allowed in tunableifs, in-statements,
macros, and booleanifs, there are tree node pointers that point to
each of these kinds of statements when its block is being parsed.
If the pointer is non-NULL, then the rule being parsed is in the block
of that kind of statement.

The tree node pointers were being updated at the wrong point which
prevented an invalid statement from being found if it was the first
statement in the block of a tunableif, in-statement, macro, or
booleanif.

Create a first child helper function for walking the parse tree and
in that function set the appropriate tree node pointer if the
current AST node is a tunableif, in-statement, macro, or booleanif.
This also makes the code symmetrical with the last child helper
where the tree node pointers are set to NULL.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 14:05:07 -04:00
James Carter
f043078f1d libsepol/cil: Cleanup build AST helper functions
Since parse_current, finished, and extra_args can never be NULL,
remove the useless check and directly assign local variables from
extra_args.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 14:05:05 -04:00
James Carter
69bfe64cdf libsepol/cil: Reorder checks for invalid rules when building AST
Reorder checks for invalid rules in the blocks of tunableifs,
in-statements, macros, and booleanifs when building the AST for
consistency.

Order the checks in the same order the blocks will be resolved in,
so tuanbleif, in-statement, macro, booleanif, and then non-block
rules.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 14:05:03 -04:00
James Carter
e65cf030b7 libsepol/cil: Move check for the shadowing of macro parameters
In cil_gen_node(), after the declaration is added to the symbol
table, if the parent is a macro, then a check is made to ensure
the declaration does not shadow any of the macro's parameters.
This check also needs to be done when copying the AST.

Move the check for the shadowing of macro parameters to its own
function, cil_verify_decl_does_not_shadow_macro_parameter(), and
refactor cil_gen_node() and __cil_copy_node_helper() to use the
new function.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 10:40:54 -04:00
James Carter
0d4e568afe libsepol/cil: Create function cil_add_decl_to_symtab() and refactor
The functionality of adding a declaration to a symbol table is also
needed in __cil_copy_node_helper() and not just cil_gen_node().

Create a new function called cil_add_decl_to_symtab() to add a
declaration to a symtab and refactor cil_gen_node() and
__cil_copy_node_helper() to use the new function.

By using the new function, __cil_copy_node_helper() will now allow
duplicate declarations when appropriate.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 10:40:52 -04:00
James Carter
63ce05ba07 libsepol/cil: Refactor helper function for cil_gen_node()
Change the name of cil_is_datum_multiple_decl() to
cil_allow_multiple_decls() and make it static. The new function
takes the CIL db and the flavors of the old and new datum as
arguments. Also, put all of the logic of determining if multiple
declarations are allowed into the new function. Finally, update
the call from cil_gen_node().

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 10:40:49 -04:00
James Carter
22fb6f477b libsepol/cil: Allow permission expressions when using map classes
The following policy will cause a segfault:
  (class CLASS (PERM))
  (class C (P1 P2 P3))
  (classorder (CLASS C))
  (sid SID)
  (sidorder (SID))
  (user USER)
  (role ROLE)
  (type TYPE)
  (category CAT)
  (categoryorder (CAT))
  (sensitivity SENS)
  (sensitivityorder (SENS))
  (sensitivitycategory SENS (CAT))
  (allow TYPE self (CLASS (PERM)))
  (roletype ROLE TYPE)
  (userrole USER ROLE)
  (userlevel USER (SENS))
  (userrange USER ((SENS)(SENS (CAT))))
  (sidcontext SID (USER ROLE TYPE ((SENS)(SENS))))

  (classmap CM (PM1 PM2 PM3))
  (classmapping CM PM1 (C (P1)))
  (classmapping CM PM2 (C (P2)))
  (classmapping CM PM3 (C (P3)))
  (allow TYPE self (CM (and (all) (not PM2))))

The problem is that, while permission expressions are allowed for
normal classes, map classes are expected to only have permission
lists and no check is done to verify that only a permission list
is being used.

When the above policy is parsed, the "and" and "all" are seen as
expression operators, but when the map permissions are converted to
normal class and permissions, the permission expression is assumed
to be a list of datums and since the operators are not datums a
segfault is the result.

There is no reason to limit map classes to only using a list of
permissions and, in fact, it would be better to be able to use them
in the same way normal classes are used.

Allow permissions expressions to be used for map classes by first
evaluating the permission expression and then converting the
resulting list to normal classes and permissions.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 10:40:46 -04:00
James Carter
532469a251 libsepol/cil: Exit with an error if declaration name is a reserved word
When CIL parses sets or conditional expressions, any identifier that
matches an operator name will always be taken as an operator. If a
declaration has the same name as an operator, then there is the
possibility of causing either confusion or a syntax error if it is
used in an expression. The potential for problems is much greater
than any possible advantage in allowing a declaration to share the
name of a reserved word.

Create a new function, __cil_is_reserved_name() that is called when
an identifier is declared and its name is being validated. In this
function, check if the declaration has the same name as a reserved
word for an expression operator that can be used with the identifer's
flavor and exit with an error if it does.

Also, move the check for types, type aliases, and type attributes
matching the reserved word "self" to this new function.

Finally, change the name of the function __cil_verify_name() to
cil_verify_name(), since this function is neither static nor a
helper function.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 10:40:43 -04:00
James Carter
e978e7692e libsepol/cil: More strict verification of constraint leaf expressions
In constraint expressions u1, u3, r1, r3, t1, and t3 are never
allowed on the right side of an expression, but there were no checks
to verify that they were not used on the right side. The result was
that the expression "(eq t1 t1)" would be silently turned into
"(eq t1 t2)" when the binary policy was created.

Verify that u1, u3, r1, r3, t1, and t3 are not used on the right
side of a constraint expression.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 10:40:40 -04:00
James Carter
a7a80ef51b libsepol/cil: Set class field to NULL when resetting struct cil_classperms
The class field of a struct cil_classperms points to the class looked
up in the symbol table, so that field should be set to NULL when
the cil_classperms is reset.

Set the class field to NULL when resetting the struct cil_classperms.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 10:40:38 -04:00
James Carter
c49a8ea095 libsepol/cil: cil_reset_classperms_set() should not reset classpermission
In struct cil_classperms_set, the set field is a pointer to a
struct cil_classpermission which is looked up in the symbol table.
Since the cil_classperms_set does not create the cil_classpermission,
it should not reset it.

Set the set field to NULL instead of resetting the classpermission
that it points to.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 10:40:35 -04:00
James Carter
2d35fcc7e9 libsepol/cil: Destroy classperm list when resetting map perms
Map perms share the same struct as regular perms, but only the
map perms use the classperms field. This field is a pointer to a
list of classperms that is created and added to when resolving
classmapping rules, so the map permission doesn't own any of the
data in the list and this list should be destroyed when the AST is
reset.

When resetting a perm, destroy the classperms list without destroying
the data in the list.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 10:40:33 -04:00
James Carter
f34d3d30c8 libsepol/cil: Destroy classperms list when resetting classpermission
Nicolas Iooss reports:
  A few months ago, OSS-Fuzz found a crash in the CIL compiler, which
  got reported as
  https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=28648 (the title
  is misleading, or is caused by another issue that conflicts with the
  one I report in this message). Here is a minimized CIL policy which
  reproduces the issue:

  (class CLASS (PERM))
  (classorder (CLASS))
  (sid SID)
  (sidorder (SID))
  (user USER)
  (role ROLE)
  (type TYPE)
  (category CAT)
  (categoryorder (CAT))
  (sensitivity SENS)
  (sensitivityorder (SENS))
  (sensitivitycategory SENS (CAT))
  (allow TYPE self (CLASS (PERM)))
  (roletype ROLE TYPE)
  (userrole USER ROLE)
  (userlevel USER (SENS))
  (userrange USER ((SENS)(SENS (CAT))))
  (sidcontext SID (USER ROLE TYPE ((SENS)(SENS))))

  (classpermission CLAPERM)

  (optional OPT
      (roletype nonexistingrole nonexistingtype)
      (classpermissionset CLAPERM (CLASS (PERM)))
  )

  The CIL policy fuzzer (which mimics secilc built with clang Address
  Sanitizer) reports:

  ==36541==ERROR: AddressSanitizer: heap-use-after-free on address
  0x603000004f98 at pc 0x56445134c842 bp 0x7ffe2a256590 sp
  0x7ffe2a256588
  READ of size 8 at 0x603000004f98 thread T0
      #0 0x56445134c841 in __cil_verify_classperms
  /selinux/libsepol/src/../cil/src/cil_verify.c:1620:8
      #1 0x56445134a43e in __cil_verify_classpermission
  /selinux/libsepol/src/../cil/src/cil_verify.c:1650:9
      #2 0x56445134a43e in __cil_pre_verify_helper
  /selinux/libsepol/src/../cil/src/cil_verify.c:1715:8
      #3 0x5644513225ac in cil_tree_walk_core
  /selinux/libsepol/src/../cil/src/cil_tree.c:272:9
      #4 0x564451322ab1 in cil_tree_walk
  /selinux/libsepol/src/../cil/src/cil_tree.c:316:7
      #5 0x5644513226af in cil_tree_walk_core
  /selinux/libsepol/src/../cil/src/cil_tree.c:284:9
      #6 0x564451322ab1 in cil_tree_walk
  /selinux/libsepol/src/../cil/src/cil_tree.c:316:7
      #7 0x5644512b88fd in cil_pre_verify
  /selinux/libsepol/src/../cil/src/cil_post.c:2510:7
      #8 0x5644512b88fd in cil_post_process
  /selinux/libsepol/src/../cil/src/cil_post.c:2524:7
      #9 0x5644511856ff in cil_compile
  /selinux/libsepol/src/../cil/src/cil.c:564:7

The classperms list of a classpermission rule is created and filled
in when classpermissionset rules are processed, so it doesn't own any
part of the list and shouldn't retain any of it when it is reset.

Destroy the classperms list (without destroying the data in it)  when
resetting a classpermission rule.

Reported-by: Nicolas Iooss <nicolas.iooss@m4x.org>
Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 10:40:29 -04:00
James Carter
e13c816265 libsepol/cil: Fix out-of-bound read of file context pattern ending with "\"
Based on patch by Nicolas Iooss, who writes:
  OSS-Fuzz found a Heap-buffer-overflow in the CIL compiler when trying
  to compile the following policy:

    (sid SID)
    (sidorder(SID))
    (filecon "\" any ())
    (filecon "" any ())

  When cil_post_fc_fill_data() processes "\", it goes beyond the NUL
  terminator of the string. Fix this by returning when '\0' is read
  after a backslash.

To be consistent with the function compute_diffdata() in
refpolicy/support/fc_sort.py, also increment str_len in this case.

Fixes: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=28484
Reported-by: Nicolas Iooss <nicolas.iooss@m4x.org>
Signed-off-by: James Carter <jwcart2@gmail.com>
2021-04-19 10:40:26 -04:00
Yi-Yo Chiang
d1a34d3f1d secilc.c: Don't fail if input file is empty
fread(3) returns zero if |size| is zero. This confuses secilc, and
causes it to fail with a "Failure reading file" error, even though there
is no error.

Add a shortcut that closes and skips an input file if file size is zero.

Signed-off-by: Yi-Yo Chiang <yochiang@google.com>
2021-04-14 15:14:59 -04:00
Dominick Grift
1e4e7f6a12 cil_conditional_statements.md: fix expr definition
expr "(expr (tunable_id tunable_id))" does not work but "(expr
tunable_id tunable_id)" does work

for example, this works

(tunable test1)
(tunable test2)
(tunableif (or test1 test2)
	   (true
	    (allow a b (c (d)))))

but this does not work:

(tunable test1)
(tunable test2)
(tunableif (or (test1 test2))
	   (true
	    (allow a b (c (d)))))

Signed-off-by: Dominick Grift <dominick.grift@defensec.nl>
2021-03-29 11:06:11 -04:00
James Carter
d155b410d4 libsepol/cil: Check for duplicate blocks, optionals, and macros
In CIL, blocks, optionals, and macros share the same symbol table so
that the targets of "in" statements can be located. Because of this,
they cannot have the same name in the same namespace, but, because
they do not show up in the final policy, they can have the same name
as long as they are in different namespaces. Unfortunately, when
copying from one namespace to another, no check was being done to see
if there was a conflict.

When copying blocks, optionals, and macros, if a datum is found in
the destination namespace, then there is a conflict with a previously
declared block, optional, or macro, so exit with an error.

Reported-by: Nicolas Iooss <nicolas.iooss@m4x.org>
Reported-by: Evgeny Vereshchagin <evvers@ya.ru>
Signed-off-by: James Carter <jwcart2@gmail.com>
2021-03-18 10:19:06 -04:00
James Carter
b839e9a1cb libsepol: Write "NO_IDENTIFIER" for empty CIL constraint expression
If a role or user attribute with nothing associated with it is used
in a constraint expression, then the bitmap will be empty. This is
not a problem for the kernel, but does cause problems when converting
a kernel policy or module to CIL.

When creating a CIL policy from a kernel policy or module, if an
empty bitmap is encountered, use the string "NO_IDENTIFIER". An
error will occur if an attempt is made to compile the resulting
policy, but a valid policy was not being produced before anyway.
Treat types the same way even though empty bitmaps are not expected.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-03-18 10:09:16 -04:00
James Carter
6758addf85 libsepol: Enclose identifier lists in CIL constraint expressions
When writing CIL policy from a kernel policy or module, if there are
multiple users, roles, or types, then the list needs to be enclosed
by "(" and ")".

When writing a constraint expression, check to see if there are
multiple identifiers in the names string and enclose the list with
"(" and ")" if there are.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-03-18 10:09:12 -04:00
James Carter
45d7a0a563 secilc/docs: Lists are now allowed in constraint expressions
Update the CIL documentation to show that lists are allowed in
constraint expressions.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-03-18 10:09:08 -04:00
James Carter
48ca44c8bc libsepol/cil: Allow lists in constraint expressions
The expectation in CIL was to use user, role, or type attributes in
constraint expressions. The problem is that neither user nor role
attributes are part of the kernel binary policy, so when converting
from a kernel policy to CIL, that would require the creation of a
role or user attribute. The better solution is to just allow a list
to be used. In fact, the only thing preventing a list to be used
is a check in cil_verify_constraint_leaf_expr_syntax().

Remove the check and allow lists in constraint expressions.

The following is now allowed:
  (constrain (CLASS1 (PERM1)) (eq r1 (ROLE1 ROLE2 ROLE_ATTR3)))

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-03-18 10:09:04 -04:00
James Carter
dbe890ab9f libsepol: Enclose identifier lists in constraint expressions
When writing a policy.conf from a kernel policy, if there are
multiple users, roles, or types, then the list needs to be enclosed
by "{" and "}".

When writing a constraint expression, check to see if there are
multiple identifiers in the names string and enclose the list
with "{" and "}" if there are.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-03-18 10:07:41 -04:00
James Carter
d4d0955c67 libsepol: Write "NO_IDENTIFIER" for empty constraint expression
If a role attribute with no roles associated with it is used in a
constraint expression, then the role bitmap will be empty. This is
not a problem for the kernel, but does cause problems when
converting a kernel policy to policy.conf.

When creating a policy.conf from a kernel policy, if an empty bitmap
is encountered, use the string "NO_IDENTIFIER". An error will occur
if an attempt is made to compile the resulting policy, but this is
better than exiting with an error without creating a policy.conf.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-03-18 10:07:04 -04:00
Nicolas Iooss
13eaba21ef libsepol: make num_* unsigned int in module_to_cil
Using signed integer to represent counts can troube some gcc
optimisation passes, for example in
https://github.com/fishilico/selinux/runs/2125501324?check_suite_focus=true#step:9:107

      In function ‘name_list_to_string’,
          inlined from ‘constraint_expr_to_string’ at module_to_cil.c:1799:11:
      module_to_cil.c:1156:8: error: argument 1 range
      [18446744071562067968, 18446744073709551615] exceeds maximum
      object size 9223372036854775807 [-Werror=alloc-size-larger-than=]
       1156 |  str = malloc(len);
            |        ^~~~~~~~~~~
      In file included from module_to_cil.c:39:
      module_to_cil.c: In function ‘constraint_expr_to_string’:
      /usr/include/stdlib.h:539:14: note: in a call to allocation
      function ‘malloc’ declared here
        539 | extern void *malloc (size_t __size) __THROW __attribute_malloc__
            |              ^~~~~~

The wide range (from 18446744071562067968 = 0xffffffff80000000 to
18446744073709551615 = 0xffffffffffffffff) was caused by num_names being
a signed int used in "len += num_names;", even though it should always
be non-negative.

Prevent such issues from occurring by using "unsigned int" where
appropriate.

Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
2021-03-18 10:04:57 -04:00
Nicolas Iooss
78d458d163
libsepol/cil: do not leak avrulex_ioctl_table memory when an error occurs
OSS-Fuzz found a memory leak when trying to compile the following
policy:

    (class CLASS (PERM ioctl))
    (classorder (CLASS))
    (sid SID)
    (sidorder (SID))
    (user USER)
    (role ROLE)
    (type TYPE)
    (category CAT)
    (categoryorder (CAT))
    (sensitivity SENS)
    (sensitivityorder (SENS))
    (sensitivitycategory SENS (CAT))
    (allow TYPE self (CLASS (PERM)))
    (roletype ROLE TYPE)
    (userrole USER ROLE)
    (userlevel USER (SENS))
    (userrange USER ((SENS)(SENS (CAT))))
    (sidcontext SID (USER ROLE TYPE ((SENS)(SENS))))

    (permissionx ioctl_test (ioctl CLASS (and (range 0x1600 0x19FF) (not (range 0x1750 0x175F)))))
    (allowx TYPE TYPE ioctl_test)

    (boolean BOOLEAN false)

    (booleanif (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (not (xor (eq BOOLEAN BOOLEAN)
                (and (eq BOOLEAN BOOLEAN) BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
                BOOLEAN ) ) )
        (true
            (allow TYPE TYPE (CLASS (PERM)))
        )
    )

When the CIL compiler reports "Conditional expression exceeded max
allowable depth" because of the loooooong expression in the booleanif
statement, cil_binary_create_allocated_pdb returns without freeing the
memory which was allocated to store the keys and values of hash table
avrulex_ioctl_table.

Fix this by moving the freeing logic to a dedicated destructor function
and calling it in the exit block of cil_binary_create_allocated_pdb.

Fixes: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=28618
Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
2021-03-17 08:46:36 +01:00
Nicolas Iooss
c5e6153720
libsepol/cil: fix NULL pointer dereference in __cil_insert_name
OSS-Fuzz found a Null-dereference in __cil_insert_name when trying to
compile the following policy:

    (macro MACRO ()
        (classmap CLASS (PERM))
        (type TYPE)
        (typetransition TYPE TYPE CLASS "name" TYPE)
    )
    (call MACRO)

When using a macro with no argument, macro->params is NULL and
cil_list_for_each(item, macro->params) dereferenced a NULL pointer.
Fix this by checking that macro->params is not NULL before using it.

Fixes: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=28565
Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
2021-03-17 08:46:36 +01:00
Nicolas Iooss
68e8871cfc
libsepol/cil: replace printf with proper cil_tree_log
All functions of the CIL compiler use cil_log or cil_tree_log to report
errors, but in two places which still uses printf. Replace these printf
invocation with cil_tree_log.

Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
2021-03-17 08:46:35 +01:00
Nicolas Iooss
fba672edfb
libsepol/cil: remove stray printf
printf("%i\n", node->flavor); looks very much like a statement which was
added for debugging purpose and was unintentionally left.

Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
2021-03-17 08:46:34 +01:00
Nicolas Iooss
ba5fb7a41b
libsepol/cil: make cil_post_fc_fill_data static
cil_post_fc_fill_data() is not used outside of cil_post.c, and is not
exported in libsepol.so. Make it static, in order to ease the analysis
of static analyzers.

While at it, make its path argument "const char*" and the fields of
"struct fc_data" "unsigned int" or "size_t", in order to make the types
better match the values.

Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
2021-03-17 08:46:33 +01:00
James Carter
43c5ed469c
libsepol: Check kernel to CIL and Conf functions for supported versions
For policy versions between 20 and 23, attributes exist in the
policy, but only in the type_attr_map. This means that there are
gaps in both the type_val_to_struct and p_type_val_to_name arrays
and policy rules can refer to those gaps which can lead to NULL
dereferences when using sepol_kernel_policydb_to_conf() and
sepol_kernel_policydb_to_cil().

This can be seen with the following policy:
  class CLASS1
  sid SID1
  class CLASS1 { PERM1 }
  attribute TYPE_ATTR1;
  type TYPE1;
  typeattribute TYPE1 TYPE_ATTR1;
  allow TYPE_ATTR1 self : CLASS1 PERM1;
  role ROLE1;
  role ROLE1 types TYPE1;
  user USER1 roles ROLE1;
  sid SID1 USER1:ROLE1:TYPE1

Compile the policy:
  checkpolicy -c 23 -o policy.bin policy.conf
Converting back to a policy.conf causes a segfault:
  checkpolicy -F -b -o policy.bin.conf policy.bin

Have both sepol_kernel_policydb_to_conf() and
sepol_kernel_policydb_to_cil() exit with an error if the kernel
policy version is between 20 and 23.

Acked-by: Nicolas Iooss <nicolas.iooss@m4x.org>
Signed-off-by: James Carter <jwcart2@gmail.com>
2021-03-15 21:52:04 +01:00
James Carter
750cc1136d
checkpolicy: Do not automatically upgrade when using "-b" flag
When reading a binary policy, do not automatically change the version
to the max policy version supported by libsepol or, if specified, the
value given using the "-c" flag.

If the binary policy version is less than or equal to version 23
(POLICYDB_VERSION_PERMISSIVE) than do not automatically upgrade the
policy and if a policy version is specified by the "-c" flag, only set
the binary policy to the specified version if it is lower than the
current version.

If the binary policy version is greater than version 23 than it should
be set to the maximum version supported by libsepol or, if specified,
the value given by the "-c" flag.

The reason for this change is that policy versions 20
(POLICYDB_VERSION_AVTAB) to 23 have a more primitive support for type
attributes where the datums are not written out, but they exist in the
type_attr_map. This means that when the binary policy is read by
libsepol, there will be gaps in the type_val_to_struct and
p_type_val_to_name arrays and policy rules can refer to those gaps.
Certain libsepol functions like sepol_kernel_policydb_to_conf() and
sepol_kernel_policydb_to_cil() do not support this behavior and need
to be able to identify these policies. Policies before version 20 do not
support attributes at all and can be handled by all libsepol functions.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-03-15 21:52:03 +01:00
James Carter
dcd07fdcbf
libsepol/checkpolicy: Set user roles using role value instead of dominance
Roles in an optional block have two datums, one in the global block
and one in the avrule_decl where it is declared. The datum in the
global block does not have its dominace set. This is a problem because
the function set_user_role() sets the user's roles based on the global
datum's dominance ebitmap. If a user is declared with an associated role
that was declared in an optional block, then it will not have any roles
set for it because the dominance ebitmap is empty.

Example/
  # handle_unknown deny
  class CLASS1
  sid kernel
  class CLASS1 { PERM1 }
  type TYPE1;
  allow TYPE1 self:CLASS1 PERM1;
  role ROLE1;
  role ROLE1 types { TYPE1 };
  optional {
    require {
      class CLASS1 { PERM1 };
    }
    role ROLE1A;
    user USER1A roles ROLE1A;
  }
  user USER1 roles ROLE1;
  sid kernel USER1:ROLE1:TYPE1

In this example, USER1A would not have ROLE1A associated with it.

Instead of using dominance, which has been deprecated anyway, just
set the bit corresponding to the role's value in the user's roles
ebitmap in set_user_role().

Signed-off-by: James Carter <jwcart2@gmail.com>
Acked-by: Nicolas Iooss <nicolas.iooss@m4x.org>

[N.I: added spaces around "-" operator]
2021-03-15 21:50:58 +01:00
James Carter
859857def9
libsepol: Remove unnecessary copying of declarations from link.c
At one point link_modules() might have needed this initial copying,
but now it serves no purpose, so remove it.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-03-15 21:48:16 +01:00
James Carter
6015b05d06
libsepol: Properly handle types associated to role attributes
Types associated to role attributes in optional blocks are not
associated with the roles that have that attribute. The problem
is that role_fix_callback is called before the avrule_decls are
walked.

Example/
  class CLASS1
  sid kernel
  class CLASS1 { PERM1 }
  type TYPE1;
  type TYPE1A;
  allow TYPE1 self : CLASS1 PERM1;
  attribute_role ROLE_ATTR1A;
  role ROLE1;
  role ROLE1A;
  roleattribute ROLE1A ROLE_ATTR1A;
  role ROLE1 types TYPE1;
  optional {
    require {
      class CLASS1 PERM1;
    }
    role ROLE_ATTR1A types TYPE1A;
  }
  user USER1 roles ROLE1;
  sid kernel USER1:ROLE1:TYPE1

In this example ROLE1A will not have TYPE1A associated to it.

Call role_fix_callback() after the avrule_decls are walked.

Signed-off-by: James Carter <jwcart2@gmail.com>
2021-03-15 21:48:07 +01:00
James Carter
f7431d0e0e
libsepol: Expand role attributes in constraint expressions
When creating the kernel binary policy, role attributes in constraint
expressions are not expanded. This causes the constraint expression
to refer to a non-existent role in the kernel policy. This can lead
to a segfault when converting the binary policy back to conf or CIL
source or when using policy tools such as seinfo.

Expand role attributes in constraint expressions when creating the
kernel binary policy.

Reported-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: James Carter <jwcart2@gmail.com>
2021-03-15 21:47:56 +01:00