From: Dave Hansen <dave.hansen@linux.intel.com> To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Dave Hansen <dave.hansen@linux.intel.com>, tim.gardner@canonical.com, jarkko@kernel.org, reinette.chatre@intel.com, shuah@kernel.org, linux-sgx@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH] selftests/sgx: remove checks for file execute permissions Date: Mon, 21 Jun 2021 12:05:56 -0700 [thread overview] Message-ID: <20210621190556.4B5DCBB1@viggo.jf.intel.com> (raw) 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 --- 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); _
WARNING: multiple messages have this Message-ID (diff)
From: Dave Hansen <dave.hansen@linux.intel.com> To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org,Dave Hansen <dave.hansen@linux.intel.com>,tim.gardner@canonical.com,jarkko@kernel.org,reinette.chatre@intel.com,shuah@kernel.org,linux-sgx@vger.kernel.org,linux-kselftest@vger.kernel.org Subject: [PATCH] selftests/sgx: remove checks for file execute permissions Date: Mon, 21 Jun 2021 12:05:56 -0700 [thread overview] Message-ID: <20210621190556.4B5DCBB1@viggo.jf.intel.com> (raw) 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 --- 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); _
next reply other threads:[~2021-06-21 19:06 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-06-21 19:05 Dave Hansen [this message] 2021-06-21 19:05 ` [PATCH] selftests/sgx: remove checks for file execute permissions Dave Hansen 2021-06-21 21:08 ` Reinette Chatre 2021-06-21 21:18 ` Dave Hansen 2021-06-24 0:40 ` Shuah Khan 2021-06-23 13:41 ` Jarkko Sakkinen
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