selftests/sgx: Fix uninitialized pointer dereferences in encl_get_entry

Ensure sym_tab and sym_names are zero-initialized and add an early-out
condition in the unlikely (erroneous) case that the enclave ELF file would
not contain a symbol table.

This addresses -Werror=maybe-uninitialized compiler warnings for gcc -O2.

Fixes: 33c5aac3bf32 ("selftests/sgx: Test complete changing of page type flow")
Signed-off-by: Jo Van Bulck <jo.vanbulck@cs.kuleuven.be>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lore.kernel.org/all/20231005153854.25566-3-jo.vanbulck%40cs.kuleuven.be

selftests/sgx: Test complete changing of page type flow

Support for changing an enclave page's type enables an initialized
enclave to be expanded with support for more threads by changing the
type of a regular enclave page to that of a Thread Control Structure
(TCS). Additionally, being able to change a TCS or regular enclave
page's type to be trimmed (SGX_PAGE_TYPE_TRIM) initiates the removal
of the page from the enclave.

Test changing page type to TCS as well as page removal flows
in two phases: In the first phase support for a new thread is
dynamically added to an initialized enclave and in the second phase
the pages associated with the new thread are removed from the enclave.
As an additional sanity check after the second phase the page used as
a TCS page during the first phase is added back as a regular page and
ensured that it can be written to (which is not possible if it was a
TCS page).

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lkml.kernel.org/r/d05b48b00338683a94dcaef9f478540fc3d6d5f9.1652137848.git.reinette.chatre@intel.com

selftests/sgx: Fix NULL-pointer-dereference upon early test failure

== Background ==

The SGX selftests track parts of the enclave binaries in an array:
encl->segment_tbl[]. That array is dynamically allocated early
(but not first) in the test's lifetime. The array is referenced
at the end of the test in encl_delete().

== Problem ==

encl->segment_tbl[] can be NULL if the test fails before its
allocation. That leads to a NULL-pointer-dereference in encl_delete().
This is triggered during early failures of the selftest like if the
enclave binary ("test_encl.elf") is deleted.

== Solution ==

Ensure encl->segment_tbl[] is valid before attempting to access
its members. The offset with which it is accessed, encl->nr_segments,
is initialized before encl->segment_tbl[] and thus considered valid
to use after the encl->segment_tbl[] check succeeds.

Fixes: 3200505d4de6 ("selftests/sgx: Create a heap for the test enclave")
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lkml.kernel.org/r/90a31dfd640ea756fa324712e7cbab4a90fa7518.1644355600.git.reinette.chatre@intel.com

selftests/sgx: Create a heap for the test enclave

Create a heap for the test enclave, which is allocated from /dev/null,
and left unmeasured. This is beneficial by its own because it verifies
that an enclave built from multiple choices, works properly. If LSM
hooks are added for SGX some day, a multi source enclave has higher
probability to trigger bugs on access control checks.

The immediate need comes from the need to implement page reclaim tests.
In order to trigger the page reclaimer, one can just set the size of
the heap to high enough.

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/e070c5f23578c29608051cab879b1d276963a27a.1636997631.git.reinette.chatre@intel.com

selftests/sgx: Make data measurement for an enclave segment optional

For a heap makes sense to leave its contents "unmeasured" in the SGX
enclave build process, meaning that they won't contribute to the
cryptographic signature (a RSA-3072 signed SHA56 hash) of the enclave.

Enclaves are signed blobs where the signature is calculated both from
page data and also from "structural properties" of the pages. For
instance a page offset of *every* page added to the enclave is hashed.

For data, this is optional, not least because hashing a page has a
significant contribution to the enclave load time. Thus, where there is
no reason to hash, do not. The SGX ioctl interface supports this with
SGX_PAGE_MEASURE flag. Only when the flag is *set*, data is measured.

Add seg->measure boolean flag to struct encl_segment. Only when the
flag is set, include the segment data to the signature (represented
by SIGSTRUCT architectural structure).

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/625b6fe28fed76275e9238ec4e15ec3c0d87de81.1636997631.git.reinette.chatre@intel.com

selftests/sgx: Assign source for each segment

Define source per segment so that enclave pages can be added from different
sources, e.g. anonymous VMA for zero pages. In other words, add 'src' field
to struct encl_segment, and assign it to 'encl->src' for pages inherited
from the enclave binary.

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/7850709c3089fe20e4bcecb8295ba87c54cc2b4a.1636997631.git.reinette.chatre@intel.com

selftests/sgx: remove checks for file execute permissions

The SGX selftests can fail for a bunch of non-obvious reasons
like 'noexec' permissions on /dev (which is the default *EVERYWHERE*
it seems).

A new test mistakenly also looked for +x permission on the
/dev/sgx_enclave. File execute permissions really only apply to
the ability of execve() to work on a file, *NOT* on the ability
for an application to map the file with PROT_EXEC. SGX needs to
mmap(PROT_EXEC), but doesn't need to execve() the device file.

Remove the check.

Fixes: 4284f7acb78b ("selftests/sgx: Improve error detection and messages")
Reported-by: Tim Gardner <tim.gardner@canonical.com>
Cc: Jarkko Sakkinen <jarkko@kernel.org>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: linux-sgx@vger.kernel.org
Cc: linux-kselftest@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests/sgx: Migrate to kselftest harness

Migrate to kselftest harness. Use a fixture test with enclave initialized
and de-initialized for each of the existing three tests, in other words:

1. One FIXTURE() for managing the enclave life-cycle.
2. Three TEST_F()'s, one for each test case.

Dump lines of /proc/self/maps matching "sgx" in FIXTURE_SETUP() as this
can be very useful debugging information later on.

Amended commit log:
This migration changes the output of this test. Instead of skipping
the tests if open /dev/sgx_enclave fails, it will run all the tests
and report failures on all of them.
Shuah Khan <skhan@linuxfoundation.org>

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests/sgx: Improve error detection and messages

The SGX device file (/dev/sgx_enclave) is unusual in that it requires
execute permissions. It has to be both "chmod +x" *and* be on a
filesystem without 'noexec'.

In the future, udev and systemd should get updates to set up systems
automatically. But, for now, nobody's systems do this automatically,
and everybody gets error messages like this when running ./test_sgx:

0x0000000000000000 0x0000000000002000 0x03
0x0000000000002000 0x0000000000001000 0x05
0x0000000000003000 0x0000000000003000 0x03
mmap() failed, errno=1.

That isn't very user friendly, even for forgetful kernel developers.

Further, the test case is rather haphazard about its use of fprintf()
versus perror().

Improve the error messages. Use perror() where possible. Lastly,
do some sanity checks on opening and mmap()ing the device file so
that we can get a decent error message out to the user.

Now, if your user doesn't have permission, you'll get the following:

$ ls -l /dev/sgx_enclave
crw------- 1 root root 10, 126 Mar 18 11:29 /dev/sgx_enclave
$ ./test_sgx
Unable to open /dev/sgx_enclave: Permission denied

If you then 'chown dave:dave /dev/sgx_enclave' (or whatever), but
you leave execute permissions off, you'll get:

$ ls -l /dev/sgx_enclave
crw------- 1 dave dave 10, 126 Mar 18 11:29 /dev/sgx_enclave
$ ./test_sgx
no execute permissions on device file

If you fix that with "chmod ug+x /dev/sgx" but you leave /dev as
noexec, you'll get this:

$ mount | grep "/dev .*noexec"
udev on /dev type devtmpfs (rw,nosuid,noexec,...)
$ ./test_sgx
ERROR: mmap for exec: Operation not permitted
mmap() succeeded for PROT_READ, but failed for PROT_EXEC
check that user has execute permissions on /dev/sgx_enclave and
that /dev does not have noexec set: 'mount | grep "/dev .*noexec"'

That can be fixed with:

mount -o remount,noexec /devESC

Hopefully, the combination of better error messages and the search
engines indexing this message will help people fix their systems
until we do this properly.

[ bp: Improve error messages more. ]

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Link: https://lore.kernel.org/r/20210318194301.11D9A984@viggo.jf.intel.com

selftests/x86: Add a selftest for SGX

Add a selftest for SGX. It is a trivial test where a simple enclave
copies one 64-bit word of memory between two memory locations,
but ensures that all SGX hardware and software infrastructure is
functioning.

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Jethro Beekman <jethro@fortanix.com>
Cc: linux-kselftest@vger.kernel.org
Link: https://lkml.kernel.org/r/20201112220135.165028-21-jarkko@kernel.org