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Add new test attach1 in t_ptrace

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This test asserts that tracer sees process termination before the parent

Currently this is not true for NetBSD.

The problem has been reported in gnats as kern/51600.

Originally an early version of this test triggered kernel panic, that
was fixed by Christos Zoulas -- thanks! Appropriate fixes are as follows:
http://mail-index.netbsd.org/source-changes/2016/11/04/msg078868.html
http://mail-index.netbsd.org/source-changes/2016/11/04/msg078869.html

Mark this test as expected failure and linked with proper PR.

As an interesting note, this test uses pipe(2) to perform IPC. Use for
messages uint8_t message to be sure that it will never by transmitted
partially from a caller to a callee, this assumption simplifies the code.

Add local function await_zombie() that takes process identifier (pid).
This function uses the sysctl(7) interface to probe p_stat of a requested
process and compares it with LSZOMB.

Try to keep closing all unneeded file descriptors for pipes in order to not
run out of fds later.

Sponsored by <The NetBSD Foundation>.
This commit is contained in:
kamil 2016-11-05 01:49:53 +00:00
parent b3ba15e2be
commit b057fe9bfd
1 changed files with 164 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

166
tests/kernel/t_ptrace.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: t_ptrace.c,v 1.8 2016/11/04 09:08:11 kamil Exp $ */
/* $NetBSD: t_ptrace.c,v 1.9 2016/11/05 01:49:53 kamil Exp $ */
/*-
* Copyright (c) 2016 The NetBSD Foundation, Inc.
@ -27,15 +27,17 @@
*/
#include <sys/cdefs.h>
__RCSID("$NetBSD: t_ptrace.c,v 1.8 2016/11/04 09:08:11 kamil Exp $");
__RCSID("$NetBSD: t_ptrace.c,v 1.9 2016/11/05 01:49:53 kamil Exp $");
#include <sys/param.h>
#include <sys/types.h>
#include <sys/ptrace.h>
#include <sys/sysctl.h>
#include <sys/wait.h>
#include <err.h>
#include <errno.h>
#include <signal.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
@ -68,6 +70,34 @@ do { \
__FILE__, __LINE__, __func__, #x); \
} while (0)
/* This function is currently designed to be run in the main/parent process */
static void
await_zombie(pid_t process)
{
struct kinfo_proc2 p;
size_t len = sizeof(p);
const int name[] = {
[0] = CTL_KERN,
[1] = KERN_PROC2,
[2] = KERN_PROC_PID,
[3] = process,
[4] = sizeof(p),
[5] = 1
};
const size_t namelen = __arraycount(name);
/* Await the process becoming a zombie */
while(1) {
ATF_REQUIRE(sysctl(name, namelen, &p, &len, NULL, 0) == 0);
if (p.p_stat == LSZOMB)
break;
ATF_REQUIRE(usleep(1000) == 0);
}
}
ATF_TC(traceme1);
ATF_TC_HEAD(traceme1, tc)
@ -467,12 +497,144 @@ ATF_TC_BODY(traceme4, tc)
ATF_REQUIRE(errno == ECHILD);
}
ATF_TC(attach1);
ATF_TC_HEAD(attach1, tc)
{
atf_tc_set_md_var(tc, "descr",
"Assert that tracer sees process termination before the parent");
}
ATF_TC_BODY(attach1, tc)
{
int fds_totracee[2], fds_totracer[2], fds_fromtracer[2];
int status, rv;
const int exitval_tracee = 5;
const int exitval_tracer = 10;
pid_t tracee, tracer, wpid;
uint8_t msg = 0xde; /* dummy message for IPC based on pipe(2) */
/* XXX: Linux&FreeBSD and NetBSD have different behavior here.
* Tracer on NetBSD isn't promoted to observe - before child's parent -
* that tracee exited (and became zombie).
*/
atf_tc_expect_fail("PR kern/51600");
printf("Spawn tracee\n");
ATF_REQUIRE(pipe(fds_totracee) == 0);
ATF_REQUIRE((tracee = fork()) != -1);
if (tracee == 0) {
FORKEE_ASSERT(close(fds_totracee[1]) == 0);
/* Wait for message from the parent */
rv = read(fds_totracee[0], &msg, sizeof(msg));
FORKEE_ASSERT(rv == sizeof(msg));
_exit(exitval_tracee);
}
ATF_REQUIRE(close(fds_totracee[0]) == 0);
printf("Spawn debugger\n");
ATF_REQUIRE(pipe(fds_totracer) == 0);
ATF_REQUIRE(pipe(fds_fromtracer) == 0);
ATF_REQUIRE((tracer = fork()) != -1);
if (tracer == 0) {
/* No IPC to communicate with the child */
FORKEE_ASSERT(close(fds_totracee[1]) == 0);
FORKEE_ASSERT(close(fds_totracer[1]) == 0);
FORKEE_ASSERT(close(fds_fromtracer[0]) == 0);
FORKEE_ASSERT(ptrace(PT_ATTACH, tracee, NULL, 0) != -1);
/* Wait for tracee and assert that it was stopped w/ SIGSTOP */
wpid = waitpid(tracee, &status, 0);
FORKEE_ASSERTX(wpid == tracee);
FORKEE_ASSERTX(!WIFEXITED(status));
FORKEE_ASSERTX(!WIFCONTINUED(status));
FORKEE_ASSERTX(!WIFSIGNALED(status));
FORKEE_ASSERTX(WIFSTOPPED(status));
FORKEE_ASSERTX(WSTOPSIG(status) == SIGSTOP);
/* Resume tracee with PT_CONTINUE */
FORKEE_ASSERT(ptrace(PT_CONTINUE, tracee, (void *)1, 0) != -1);
/* Inform parent that tracer has attached to tracee */
rv = write(fds_fromtracer[1], &msg, sizeof(msg));
FORKEE_ASSERT(rv == sizeof(msg));
/* Wait for parent */
rv = read(fds_totracer[0], &msg, sizeof(msg));
FORKEE_ASSERT(rv == sizeof(msg));
/* Wait for tracee and assert that it exited */
wpid = waitpid(tracee, &status, 0);
FORKEE_ASSERTX(wpid == tracee);
FORKEE_ASSERTX(WIFEXITED(status));
FORKEE_ASSERTX(!WIFCONTINUED(status));
FORKEE_ASSERTX(!WIFSIGNALED(status));
FORKEE_ASSERTX(!WIFSTOPPED(status));
FORKEE_ASSERTX(WEXITSTATUS(status) == exitval_tracee);
_exit(exitval_tracer);
}
ATF_REQUIRE(close(fds_totracer[0]) == 0);
ATF_REQUIRE(close(fds_fromtracer[1]) == 0);
printf("Wait for the tracer to attach to the tracee\n");
rv = read(fds_fromtracer[0], &msg, sizeof(msg));
ATF_REQUIRE(rv == sizeof(msg));
printf("Resume the tracee and let it exit\n");
rv = write(fds_totracee[1], &msg, sizeof(msg));
ATF_REQUIRE(rv == sizeof(msg));
printf("fds_totracee is no longer needed - close it\n");
ATF_REQUIRE(close(fds_totracee[1]) == 0);
printf("Detect that tracee is zombie\n");
await_zombie(tracee);
printf("Assert that there is no status about tracee - "
"Tracer must detect zombie first\n");
wpid = waitpid(tracee, &status, WNOHANG);
ATF_REQUIRE(wpid == 0);
printf("Resume the tracer and let it detect exited tracee\n");
rv = write(fds_totracer[1], &msg, sizeof(msg));
ATF_REQUIRE(rv == sizeof(msg));
printf("Wait for tracer to finish its job and exit\n");
wpid = waitpid(tracer, &status, 0);
ATF_REQUIRE(wpid == tracer);
ATF_REQUIRE(WIFEXITED(status));
ATF_REQUIRE(!WIFCONTINUED(status));
ATF_REQUIRE(!WIFSIGNALED(status));
ATF_REQUIRE(!WIFSTOPPED(status));
ATF_REQUIRE(WEXITSTATUS(status) == exitval_tracer);
printf("Wait for tracer to finish its job and exit\n");
wpid = waitpid(tracee, &status, WNOHANG);
ATF_REQUIRE(wpid == tracee);
ATF_REQUIRE(WIFEXITED(status));
ATF_REQUIRE(!WIFCONTINUED(status));
ATF_REQUIRE(!WIFSIGNALED(status));
ATF_REQUIRE(!WIFSTOPPED(status));
ATF_REQUIRE(WEXITSTATUS(status) == exitval_tracee);
printf("fds_fromtracer is no longer needed - close it\n");
ATF_REQUIRE(close(fds_fromtracer[0]) == 0);
printf("fds_totracer is no longer needed - close it\n");
ATF_REQUIRE(close(fds_totracer[1]) == 0);
}
ATF_TP_ADD_TCS(tp)
{
ATF_TP_ADD_TC(tp, traceme1);
ATF_TP_ADD_TC(tp, traceme2);
ATF_TP_ADD_TC(tp, traceme3);
ATF_TP_ADD_TC(tp, traceme4);
ATF_TP_ADD_TC(tp, attach1);
return atf_no_error();
}