@@ -50,6 +50,11 @@
#define PIDFD_NONBLOCK O_NONBLOCK
#endif
+/* System header file may not have this available. */
+#ifndef PIDFD_SELF
+#define PIDFD_SELF -200
+#endif
+
/*
* The kernel reserves 300 pids via RESERVED_PIDS in kernel/pid.c
* That means, when it wraps around any pid < 300 will be skipped.
@@ -15,6 +15,7 @@
#include <sys/prctl.h>
#include <sys/wait.h>
#include <unistd.h>
+#include <sys/mman.h>
#include <sys/socket.h>
#include <linux/kcmp.h>
@@ -264,6 +265,43 @@ TEST_F(child, no_strange_EBADF)
EXPECT_EQ(errno, ESRCH);
}
+TEST(pidfd_self)
+{
+ int memfd = sys_memfd_create("test_self", 0);
+ long page_size = sysconf(_SC_PAGESIZE);
+ int newfd;
+ char *ptr;
+
+ ASSERT_GE(memfd, 0);
+ ASSERT_EQ(ftruncate(memfd, page_size), 0);
+
+ /*
+ * Map so we can assert that the duplicated fd references the same
+ * memory.
+ */
+ ptr = mmap(NULL, page_size, PROT_READ | PROT_WRITE,
+ MAP_SHARED, memfd, 0);
+ ASSERT_NE(ptr, MAP_FAILED);
+ ptr[0] = 'x';
+ ASSERT_EQ(munmap(ptr, page_size), 0);
+
+ /* Now get a duplicate of our memfd. */
+ newfd = sys_pidfd_getfd(PIDFD_SELF, memfd, 0);
+ ASSERT_GE(newfd, 0);
+ ASSERT_NE(memfd, newfd);
+
+ /* Now map duplicate fd and make sure it references the same memory. */
+ ptr = mmap(NULL, page_size, PROT_READ | PROT_WRITE,
+ MAP_SHARED, newfd, 0);
+ ASSERT_NE(ptr, MAP_FAILED);
+ ASSERT_EQ(ptr[0], 'x');
+ ASSERT_EQ(munmap(ptr, page_size), 0);
+
+ /* Cleanup. */
+ close(memfd);
+ close(newfd);
+}
+
#if __NR_pidfd_getfd == -1
int main(void)
{
@@ -752,4 +752,10 @@ TEST(setns_einval)
close(fd);
}
+TEST(setns_pidfd_self_disallowed)
+{
+ ASSERT_EQ(setns(PIDFD_SELF, 0), -1);
+ EXPECT_EQ(errno, EBADF);
+}
+
TEST_HARNESS_MAIN
@@ -85,6 +85,19 @@ static int test_pidfd_send_signal_simple_success(void)
test_name);
signal_received = 0;
+
+ /* Now try the same thing only using PIDFD_SELF. */
+ ret = sys_pidfd_send_signal(PIDFD_SELF, SIGUSR1, NULL, 0);
+ if (ret < 0)
+ ksft_exit_fail_msg("%s test: Failed to send PIDFD_SELF signal\n",
+ test_name);
+
+ if (signal_received != 1)
+ ksft_exit_fail_msg("%s test: Failed to receive PIDFD_SELF signal\n",
+ test_name);
+
+ signal_received = 0;
+
ksft_test_result_pass("%s test: Sent signal\n", test_name);
return 0;
}
Add tests to assert that PIDFD_SELF correctly refers to the current process. This is only practically meaningful to pidfd_send_signal() and pidfd_getfd(), but also explicitly test that we disallow this feature for setns() where it would make no sense. We cannot reasonably wait on ourself using waitid(P_PIDFD, ...) so while in theory PIDFD_SELF would work here, we'd be left blocked if we tried it. We defer testing of mm-specific functionality which uses pidfd, namely process_madvise() and process_mrelease() to mm testing (though note the latter can not be sensibly tested as it would require the testing process to be dying). Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> --- tools/testing/selftests/pidfd/pidfd.h | 5 +++ .../selftests/pidfd/pidfd_getfd_test.c | 38 +++++++++++++++++++ .../selftests/pidfd/pidfd_setns_test.c | 6 +++ tools/testing/selftests/pidfd/pidfd_test.c | 13 +++++++ 4 files changed, 62 insertions(+)