Re: [PATCH] selftests/x86: Fix malformed src_offset initialization

Borislav Petkov
2020-11-18T11:11:32Z

On Wed, Nov 18, 2020 at 12:36:30AM +0200, Jarkko Sakkinen wrote:
> Assign src_offset just to the p_offset, when first initialized.
> This has been probably copy-pasting accident (at least looks like
> it).
>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: Shuah Khan <shuah@kernel.org>
> Cc: linux-kselftest@vger.kernel.org
> Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
> ---
> tools/testing/selftests/sgx/load.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/sgx/load.c b/tools/testing/selftests/sgx/load.c
> index 07988de6b767..64976f266bae 100644
> --- a/tools/testing/selftests/sgx/load.c
> +++ b/tools/testing/selftests/sgx/load.c
> @@ -185,7 +185,7 @@ bool encl_load(const char *path, struct encl *encl)
> }
>
> if (j == 0) {
> - src_offset = (phdr->p_offset & PAGE_MASK) - src_offset;
> + src_offset = (phdr->p_offset & PAGE_MASK);
>
> seg->prot = PROT_READ | PROT_WRITE;
> seg->flags = SGX_PAGE_TYPE_TCS << 8;
> --

Still no joy:

0x0000000000000000 0x0000000000002000 0x03
0x0000000000002000 0x0000000000001000 0x05
0x0000000000003000 0x0000000000003000 0x03
encl_load: encl->nr_segments: 3
encl_load: seg2 offset: 0x3000, seg2 size: 12288
encl_load: encl_size: 32768, src_size: 24576
encl_map_area: encl_size: 32768
encl_map_area: area: 0x0x7f7ec8dd8000
encl_map_area: encl_base: 0x7f7ec8dd8000
mapping segment 0, seg->prot: (read write )
base: 0x7f7ec8dd8000, offset 0x0, size: 8192
mapping segment 1, seg->prot: (read exec)
base: 0x7f7ec8dd8000, offset 0x2000, size: 4096
mmap() failed, errno=1.
mmap: Operation not permitted

That second segment is PROT_EXEC and mmap(2) manpage says:

EPERM The prot argument asks for PROT_EXEC but the mapped area belongs to a
file on a filesystem that was mounted no-exec.

EPERM The operation was prevented by a file seal; see fcntl(2).

I don't see fcntl() calls in the test and the fs I'm running it from is
not mapped "no-exec":

/dev/nvme0n1p2 on / type ext4 (rw,relatime,errors=remount-ro)

so something else is missing.

Thx.

--
Regards/Gruss,
Boris.