selftest: add a test case for PTRACE_PEEKSIGINFO

* Dump signals from process-wide and per-thread queues with
  different sizes of buffers.
* Check error paths for buffers with restricted permissions. A part of
  buffer or a whole buffer is for read-only.
* Try to get nonexistent signal.

Signed-off-by: Andrew Vagin <avagin@openvz.org>
Cc: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Dave Jones <davej@redhat.com>
Cc: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pedro Alves <palves@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 225 insertions, 0 deletions

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 5eff5f785b35..fa6ea69f2e48 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -4,6 +4,7 @@ TARGETS += efivarfs
 TARGETS += kcmp
 TARGETS += memory-hotplug
 TARGETS += mqueue
+TARGETS += ptrace
 TARGETS += soft-dirty
 TARGETS += vm
 
diff --git a/tools/testing/selftests/ptrace/Makefile b/tools/testing/selftests/ptrace/Makefile
new file mode 100644
index 000000000000..47ae2d385ce8
--- /dev/null
+++ b/tools/testing/selftests/ptrace/Makefile
@@ -0,0 +1,10 @@
+CFLAGS += -iquote../../../../include/uapi -Wall
+peeksiginfo: peeksiginfo.c
+
+all: peeksiginfo
+
+clean:
+        rm -f peeksiginfo
+
+run_tests: all
+        @./peeksiginfo || echo "peeksiginfo selftests: [FAIL]"
diff --git a/tools/testing/selftests/ptrace/peeksiginfo.c b/tools/testing/selftests/ptrace/peeksiginfo.c
new file mode 100644
index 000000000000..d46558b1f58d
--- /dev/null
+++ b/tools/testing/selftests/ptrace/peeksiginfo.c
@@ -0,0 +1,214 @@
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <signal.h>
+#include <unistd.h>
+#include <errno.h>
+#include <linux/types.h>
+#include <sys/wait.h>
+#include <sys/syscall.h>
+#include <sys/user.h>
+#include <sys/mman.h>
+
+#include "linux/ptrace.h"
+
+static int sys_rt_sigqueueinfo(pid_t tgid, int sig, siginfo_t *uinfo)
+{
+        return syscall(SYS_rt_sigqueueinfo, tgid, sig, uinfo);
+}
+
+static int sys_rt_tgsigqueueinfo(pid_t tgid, pid_t tid,
+                                        int sig, siginfo_t *uinfo)
+{
+        return syscall(SYS_rt_tgsigqueueinfo, tgid, tid, sig, uinfo);
+}
+
+static int sys_ptrace(int request, pid_t pid, void *addr, void *data)
+{
+        return syscall(SYS_ptrace, request, pid, addr, data);
+}
+
+#define SIGNR 10
+#define TEST_SICODE_PRIV        -1
+#define TEST_SICODE_SHARE       -2
+
+#define err(fmt, ...)                                           \
+                fprintf(stderr,                                 \
+                        "Error (%s:%d): " fmt,                  \
+                        __FILE__, __LINE__, ##__VA_ARGS__)
+
+static int check_error_paths(pid_t child)
+{
+        struct ptrace_peeksiginfo_args arg;
+        int ret, exit_code = -1;
+        void *addr_rw, *addr_ro;
+
+        /*
+         * Allocate two contiguous pages. The first one is for read-write,
+         * another is for read-only.
+         */
+        addr_rw = mmap(NULL, 2 * PAGE_SIZE, PROT_READ | PROT_WRITE,
+                                MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+        if (addr_rw == MAP_FAILED) {
+                err("mmap() failed: %m\n");
+                return 1;
+        }
+
+        addr_ro = mmap(addr_rw + PAGE_SIZE, PAGE_SIZE, PROT_READ,
+                        MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
+        if (addr_ro == MAP_FAILED) {
+                err("mmap() failed: %m\n");
+                goto out;
+        }
+
+        arg.nr = SIGNR;
+        arg.off = 0;
+
+        /* Unsupported flags */
+        arg.flags = ~0;
+        ret = sys_ptrace(PTRACE_PEEKSIGINFO, child, &arg, addr_rw);
+        if (ret != -1 || errno != EINVAL) {
+                err("sys_ptrace() returns %d (expected -1),"
+                                " errno %d (expected %d): %m\n",
+                                ret, errno, EINVAL);
+                goto out;
+        }
+        arg.flags = 0;
+
+        /* A part of the buffer is read-only */
+        ret = sys_ptrace(PTRACE_PEEKSIGINFO, child, &arg,
+                                        addr_ro - sizeof(siginfo_t) * 2);
+        if (ret != 2) {
+                err("sys_ptrace() returns %d (expected 2): %m\n", ret);
+                goto out;
+        }
+
+        /* Read-only buffer */
+        ret = sys_ptrace(PTRACE_PEEKSIGINFO, child, &arg, addr_ro);
+        if (ret != -1 && errno != EFAULT) {
+                err("sys_ptrace() returns %d (expected -1),"
+                                " errno %d (expected %d): %m\n",
+                                ret, errno, EFAULT);
+                goto out;
+        }
+
+        exit_code = 0;
+out:
+        munmap(addr_rw, 2 * PAGE_SIZE);
+        return exit_code;
+}
+
+int check_direct_path(pid_t child, int shared, int nr)
+{
+        struct ptrace_peeksiginfo_args arg = {.flags = 0, .nr = nr, .off = 0};
+        int i, j, ret, exit_code = -1;
+        siginfo_t siginfo[SIGNR];
+        int si_code;
+
+        if (shared == 1) {
+                arg.flags = PTRACE_PEEKSIGINFO_SHARED;
+                si_code = TEST_SICODE_SHARE;
+        } else {
+                arg.flags = 0;
+                si_code = TEST_SICODE_PRIV;
+        }
+
+        for (i = 0; i < SIGNR; ) {
+                arg.off = i;
+                ret = sys_ptrace(PTRACE_PEEKSIGINFO, child, &arg, siginfo);
+                if (ret == -1) {
+                        err("ptrace() failed: %m\n");
+                        goto out;
+                }
+
+                if (ret == 0)
+                        break;
+
+                for (j = 0; j < ret; j++, i++) {
+                        if (siginfo[j].si_code == si_code &&
+                            siginfo[j].si_int == i)
+                                continue;
+
+                        err("%d: Wrong siginfo i=%d si_code=%d si_int=%d\n",
+                             shared, i, siginfo[j].si_code, siginfo[j].si_int);
+                        goto out;
+                }
+        }
+
+        if (i != SIGNR) {
+                err("Only %d signals were read\n", i);
+                goto out;
+        }
+
+        exit_code = 0;
+out:
+        return exit_code;
+}
+
+int main(int argc, char *argv[])
+{
+        siginfo_t siginfo[SIGNR];
+        int i, exit_code = 1;
+        sigset_t blockmask;
+        pid_t child;
+
+        sigemptyset(&blockmask);
+        sigaddset(&blockmask, SIGRTMIN);
+        sigprocmask(SIG_BLOCK, &blockmask, NULL);
+
+        child = fork();
+        if (child == -1) {
+                err("fork() failed: %m");
+                return 1;
+        } else if (child == 0) {
+                pid_t ppid = getppid();
+                while (1) {
+                        if (ppid != getppid())
+                                break;
+                        sleep(1);
+                }
+                return 1;
+        }
+
+        /* Send signals in process-wide and per-thread queues */
+        for (i = 0; i < SIGNR; i++) {
+                siginfo->si_code = TEST_SICODE_SHARE;
+                siginfo->si_int = i;
+                sys_rt_sigqueueinfo(child, SIGRTMIN, siginfo);
+
+                siginfo->si_code = TEST_SICODE_PRIV;
+                siginfo->si_int = i;
+                sys_rt_tgsigqueueinfo(child, child, SIGRTMIN, siginfo);
+        }
+
+        if (sys_ptrace(PTRACE_ATTACH, child, NULL, NULL) == -1)
+                return 1;
+
+        waitpid(child, NULL, 0);
+
+        /* Dump signals one by one*/
+        if (check_direct_path(child, 0, 1))
+                goto out;
+        /* Dump all signals for one call */
+        if (check_direct_path(child, 0, SIGNR))
+                goto out;
+
+        /*
+         * Dump signal from the process-wide queue.
+         * The number of signals is not multible to the buffer size
+         */
+        if (check_direct_path(child, 1, 3))
+                goto out;
+
+        if (check_error_paths(child))
+                goto out;
+
+        printf("PASS\n");
+        exit_code = 0;
+out:
+        if (sys_ptrace(PTRACE_KILL, child, NULL, NULL) == -1)
+                return 1;
+
+        waitpid(child, NULL, 0);
+
+        return exit_code;
+}