On Mon, Jun 21, 2021 at 12:05:56PM -0700, Dave Hansen wrote:
>
> 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@xxxxxxxxxxxxx>
> Cc: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
> Cc: Reinette Chatre <reinette.chatre@xxxxxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> Cc: Shuah Khan <shuah@xxxxxxxxxx>
> Cc: linux-sgx@xxxxxxxxxxxxxxx
> Cc: linux-kselftest@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
>
> ---
>
> b/tools/testing/selftests/sgx/load.c | 16 +++-------------
> 1 file changed, 3 insertions(+), 13 deletions(-)
>
> diff -puN tools/testing/selftests/sgx/load.c~sgx-no-file-exec tools/testing/selftests/sgx/load.c
> --- a/tools/testing/selftests/sgx/load.c~sgx-no-file-exec 2021-06-21 11:48:25.226294281 -0700
> +++ b/tools/testing/selftests/sgx/load.c 2021-06-21 12:03:28.023292029 -0700
> @@ -150,16 +150,6 @@ bool encl_load(const char *path, struct
> goto err;
> }
>
> - /*
> - * This just checks if the /dev file has these permission
> - * bits set. It does not check that the current user is
> - * the owner or in the owning group.
> - */
> - if (!(sb.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH))) {
> - fprintf(stderr, "no execute permissions on device file %s\n", device_path);
> - goto err;
> - }
> -
> ptr = mmap(NULL, PAGE_SIZE, PROT_READ, MAP_SHARED, fd, 0);
> if (ptr == (void *)-1) {
> perror("mmap for read");
> @@ -169,13 +159,13 @@ bool encl_load(const char *path, struct
>
> #define ERR_MSG \
> "mmap() succeeded for PROT_READ, but failed for PROT_EXEC.\n" \
> -" Check that current user has execute permissions on %s and \n" \
> -" that /dev does not have noexec set: mount | grep \"/dev .*noexec\"\n" \
> +" Check that /dev does not have noexec set:\n" \
> +" \tmount | grep \"/dev .*noexec\"\n" \
> " If so, remount it executable: mount -o remount,exec /dev\n\n"
>
> ptr = mmap(NULL, PAGE_SIZE, PROT_EXEC, MAP_SHARED, fd, 0);
> if (ptr == (void *)-1) {
> - fprintf(stderr, ERR_MSG, device_path);
> + fprintf(stderr, ERR_MSG);
> goto err;
> }
> munmap(ptr, PAGE_SIZE);
> _
>
Reviewed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
/Jarkko
