Messages in this thread Patch in this message | | | Date | Wed, 06 Nov 2019 20:35:08 +0100 | From | Thomas Gleixner <> | Subject | [patch 9/9] selftests/x86/iopl: Verify that CLI/STI result in #GP |
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Add tests that the now emulated iopl() functionality does not longer allow user space to disable interrupts.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- tools/testing/selftests/x86/iopl.c | 104 +++++++++++++++++++++++++++++++++---- 1 file changed, 93 insertions(+), 11 deletions(-)
--- a/tools/testing/selftests/x86/iopl.c +++ b/tools/testing/selftests/x86/iopl.c @@ -35,6 +35,16 @@ static void sethandler(int sig, void (*h } +static void clearhandler(int sig) +{ + struct sigaction sa; + memset(&sa, 0, sizeof(sa)); + sa.sa_handler = SIG_DFL; + sigemptyset(&sa.sa_mask); + if (sigaction(sig, &sa, 0)) + err(1, "sigaction"); +} + static jmp_buf jmpbuf; static void sigsegv(int sig, siginfo_t *si, void *ctx_void) @@ -42,22 +52,100 @@ static void sigsegv(int sig, siginfo_t * siglongjmp(jmpbuf, 1); } +static bool try_outb(unsigned short port) +{ + sethandler(SIGSEGV, sigsegv, SA_RESETHAND); + if (sigsetjmp(jmpbuf, 1) != 0) { + return false; + } else { + asm volatile ("outb %%al, %w[port]" + : : [port] "Nd" (port), "a" (0)); + return true; + } + clearhandler(SIGSEGV); +} + +static void expect_gp_outb(unsigned short port) +{ + if (try_outb(port)) { + printf("[FAIL]\toutb to 0x%02hx worked\n", port); + nerrs++; + } + + printf("[OK]\toutb to 0x%02hx failed\n", port); +} + +static bool try_cli(void) +{ + sethandler(SIGSEGV, sigsegv, SA_RESETHAND); + if (sigsetjmp(jmpbuf, 1) != 0) { + return false; + } else { + asm volatile ("cli"); + return true; + } + clearhandler(SIGSEGV); +} + +static bool try_sti(void) +{ + sethandler(SIGSEGV, sigsegv, SA_RESETHAND); + if (sigsetjmp(jmpbuf, 1) != 0) { + return false; + } else { + asm volatile ("sti"); + return true; + } + clearhandler(SIGSEGV); +} + +static void expect_gp_sti(void) +{ + if (try_sti()) { + printf("[FAIL]\tSTI worked\n"); + nerrs++; + } else { + printf("[OK]\tSTI faulted\n"); + } +} + +static void expect_gp_cli(void) +{ + if (try_cli()) { + printf("[FAIL]\tCLI worked\n"); + nerrs++; + } else { + printf("[OK]\tCLI faulted\n"); + } +} + int main(void) { cpu_set_t cpuset; + CPU_ZERO(&cpuset); CPU_SET(0, &cpuset); if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0) err(1, "sched_setaffinity to CPU 0"); /* Probe for iopl support. Note that iopl(0) works even as nonroot. */ - if (iopl(3) != 0) { + switch(iopl(3)) { + case 0: + break; + case -ENOSYS: + printf("[OK]\tiopl() nor supported\n"); + return 0; + default: printf("[OK]\tiopl(3) failed (%d) -- try running as root\n", errno); return 0; } - /* Restore our original state prior to starting the test. */ + /* Make sure that CLI/STI are blocked even with IOPL level 3 */ + expect_gp_cli(); + expect_gp_sti(); + + /* Restore our original state prior to starting the fork test. */ if (iopl(0) != 0) err(1, "iopl(0)"); @@ -90,14 +178,9 @@ int main(void) printf("[RUN]\tparent: write to 0x80 (should fail)\n"); - sethandler(SIGSEGV, sigsegv, 0); - if (sigsetjmp(jmpbuf, 1) != 0) { - printf("[OK]\twrite was denied\n"); - } else { - asm volatile ("outb %%al, $0x80" : : "a" (0)); - printf("[FAIL]\twrite was allowed\n"); - nerrs++; - } + expect_gp_outb(0x80); + expect_gp_cli(); + expect_gp_sti(); /* Test the capability checks. */ printf("\tiopl(3)\n"); @@ -133,4 +216,3 @@ int main(void) done: return nerrs ? 1 : 0; } -
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