[LTP] [PATCH v4 2/2] pkey: add test for memory protection keys

Li Wang
2019-06-26T07:15:38Z

Memory Protection Keys for Userspace (PKU aka PKEYs) is a Skylake-SP
server feature that provides a mechanism for enforcing page-based
protections, but without requiring modification of the page tables
when an application changes protection domains. It works by dedicating
4 previously ignored bits in each page table entry to a "protection key",
giving 16 possible keys.

Basic method for PKEYs test:
1. test allocates a pkey(e.g. PKEY_DISABLE_ACCESS) via pkey_alloc()
2. pkey_mprotect() apply this pkey to a piece of memory buffer
3. check if the access right of buffer has been changed and take effect
4. remove the access right(pkey) from this buffer via pkey_mprotect()
5. check if buffer area can be read or write after removing pkey
6. pkey_free() releases the pkey after using it

Looping around this basic test on diffenrent types of memory.

Signed-off-by: Li Wang <liwang@redhat.com>
---

Notes:
v3 --> v4
* correct syscall with __NR_ prefix
* verify the value has been wrote in nr_hugepages
* tst_res() message could print also mmap flags
* add flag_to_str() function
* .needs_root = 1

configure.ac | 1 +
runtest/syscalls | 2 +
testcases/kernel/syscalls/pkeys/.gitignore | 1 +
testcases/kernel/syscalls/pkeys/Makefile | 8 +
testcases/kernel/syscalls/pkeys/pkey.h | 50 ++++
testcases/kernel/syscalls/pkeys/pkey01.c | 266 +++++++++++++++++++++
6 files changed, 328 insertions(+)
create mode 100644 testcases/kernel/syscalls/pkeys/.gitignore
create mode 100644 testcases/kernel/syscalls/pkeys/Makefile
create mode 100644 testcases/kernel/syscalls/pkeys/pkey.h
create mode 100644 testcases/kernel/syscalls/pkeys/pkey01.c

diff --git a/configure.ac b/configure.ac
index 65fc2a232..5a9b74b0a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -74,6 +74,7 @@ AC_CHECK_FUNCS([ \
pidfd_send_signal \
preadv \
preadv2 \
+ pkey_mprotect \
profil \
pwritev \
pwritev2 \
diff --git a/runtest/syscalls b/runtest/syscalls
index c6a064481..6ea991f12 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -721,6 +721,8 @@ mprotect02 mprotect02
mprotect03 mprotect03
mprotect04 mprotect04

+pkey01 pkey01
+
mq_notify01 mq_notify01
mq_notify02 mq_notify02
mq_open01 mq_open01
diff --git a/testcases/kernel/syscalls/pkeys/.gitignore b/testcases/kernel/syscalls/pkeys/.gitignore
new file mode 100644
index 000000000..6fd5addb8
--- /dev/null
+++ b/testcases/kernel/syscalls/pkeys/.gitignore
@@ -0,0 +1 @@
+/pkey01
diff --git a/testcases/kernel/syscalls/pkeys/Makefile b/testcases/kernel/syscalls/pkeys/Makefile
new file mode 100644
index 000000000..9ee2c2ea5
--- /dev/null
+++ b/testcases/kernel/syscalls/pkeys/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright (c) 2019 Red Hat, Inc.
+
+top_srcdir ?= ../../../..
+
+include $(top_srcdir)/include/mk/testcases.mk
+
+include $(top_srcdir)/include/mk/generic_leaf_target.mk
diff --git a/testcases/kernel/syscalls/pkeys/pkey.h b/testcases/kernel/syscalls/pkeys/pkey.h
new file mode 100644
index 000000000..d623244eb
--- /dev/null
+++ b/testcases/kernel/syscalls/pkeys/pkey.h
@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2019 Red Hat, Inc.
+ */
+
+#ifndef PKEYS_H
+#define PKEYS_H
+
+#include "tst_test.h"
+#include "lapi/syscalls.h"
+
+#ifndef PKEY_DISABLE_ACCESS
+# define PKEY_DISABLE_ACCESS 0x1
+# define PKEY_DISABLE_WRITE 0x2
+#endif
+
+#ifndef HAVE_PKEY_MPROTECT
+static inline int pkey_mprotect(void *addr, size_t len, int prot, int pkey)
+{
+ return tst_syscall(__NR_pkey_mprotect, addr, len, prot, pkey);
+}
+
+static inline int pkey_alloc(unsigned int flags, unsigned int access_rights)
+{
+ return tst_syscall(__NR_pkey_alloc, flags, access_rights);
+}
+
+static inline int pkey_free(int pkey)
+{
+ return tst_syscall(__NR_pkey_free, pkey);
+}
+#endif /* HAVE_PKEY_MPROTECT */
+
+static inline void check_pkey_support(void)
+{
+ int pkey = pkey_alloc(0, 0);
+
+ if (pkey == -1) {
+ if (errno == ENOSYS)
+ tst_brk(TCONF, "pkey_alloc is not implemented");
+ if (errno == EINVAL)
+ tst_brk(TCONF, "pku is not supported on this CPU");
+ if (errno == ENOSPC)
+ tst_brk(TCONF, "pkeys are not available for test");
+ }
+
+ pkey_free(pkey);
+}
+
+#endif /* PKEYS_H */
diff --git a/testcases/kernel/syscalls/pkeys/pkey01.c b/testcases/kernel/syscalls/pkeys/pkey01.c
new file mode 100644
index 000000000..e95e9eacc
--- /dev/null
+++ b/testcases/kernel/syscalls/pkeys/pkey01.c
@@ -0,0 +1,266 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2019 Red Hat, Inc.
+ *
+ * Memory Protection Keys for Userspace (PKU aka PKEYs) is a Skylake-SP
+ * server feature that provides a mechanism for enforcing page-based
+ * protections, but without requiring modification of the page tables
+ * when an application changes protection domains. It works by dedicating
+ * 4 previously ignored bits in each page table entry to a "protection key",
+ * giving 16 possible keys.
+ *
+ * Basic method for PKEYs testing:
+ * 1. test allocates a pkey(e.g. PKEY_DISABLE_ACCESS) via pkey_alloc()
+ * 2. pkey_mprotect() apply this pkey to a piece of memory(buffer)
+ * 3. check if access right of the buffer has been changed and take effect
+ * 4. remove the access right(pkey) from this buffer via pkey_mprotect()
+ * 5. check if buffer area can be read or write after removing pkey
+ * 6. pkey_free() releases the pkey after using it
+ *
+ * Looping around this basic test on diffenrent types of memory.
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <unistd.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <sys/syscall.h>
+#include <sys/mman.h>
+#include <sys/wait.h>
+
+#include "pkey.h"
+
+#define TMP_DIR "tmp_pkey"
+#define TEST_FILE TMP_DIR"/testfile"
+#define STR "abcdefghijklmnopqrstuvwxyz12345\n"
+#define PATH_VM_NRHPS "/proc/sys/vm/nr_hugepages"
+
+static int size;
+static int no_hugepage;
+
+static const char * const save_restore[] = {
+ "?/proc/sys/vm/nr_hugepages",
+ NULL,
+};
+
+static struct tcase {
+ unsigned long flags;
+ unsigned long access_rights;
+ char *name;
+} tcases[] = {
+ {0, PKEY_DISABLE_ACCESS, "PKEY_DISABLE_ACCESS"},
+ {0, PKEY_DISABLE_WRITE, "PKEY_DISABLE_WRITE"},
+};
+
+static void setup(void)
+{
+ int i, fd;
+
+ if (access(PATH_VM_NRHPS, F_OK)) {
+ tst_res(TINFO, "Huge page is not supported");
+ size = getpagesize();
+ no_hugepage = 1;
+ } else {
+ int val;
+
+ SAFE_FILE_PRINTF(PATH_VM_NRHPS, "%d", 1);
+
+ SAFE_FILE_SCANF(PATH_VM_NRHPS, "%d", &val);
+ if (val != 1)
+ tst_brk(TBROK, "nr_hugepages = %d, but expect %d",
+ val, 1);
+
+ size = SAFE_READ_MEMINFO("Hugepagesize:") * 1024;
+ }
+
+ SAFE_MKDIR(TMP_DIR, 0664);
+ SAFE_MOUNT(TMP_DIR, TMP_DIR, "tmpfs", 0, NULL);
+
+ check_pkey_support();
+
+ fd = SAFE_OPEN(TEST_FILE, O_RDWR | O_CREAT, 0664);
+ for (i = 0; i < 128; i++)
+ SAFE_WRITE(1, fd, STR, strlen(STR));
+
+ SAFE_CLOSE(fd);
+}
+
+static void cleanup(void)
+{
+ SAFE_UMOUNT(TMP_DIR);
+ SAFE_RMDIR(TMP_DIR);
+}
+
+static struct mmap_param {
+ int prot;
+ int flags;
+ int fd;
+} mmap_params[] = {
+ {PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE, -1},
+ {PROT_READ, MAP_ANONYMOUS | MAP_SHARED, -1},
+ {PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE | MAP_HUGETLB, -1},
+ {PROT_READ, MAP_ANONYMOUS | MAP_SHARED | MAP_HUGETLB, -1},
+ {PROT_READ, MAP_PRIVATE, 0},
+ {PROT_READ, MAP_SHARED, 0},
+
+ {PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, -1},
+ {PROT_WRITE, MAP_ANONYMOUS | MAP_SHARED, -1},
+ {PROT_WRITE, MAP_PRIVATE, 0},
+ {PROT_WRITE, MAP_SHARED, 0},
+ {PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE | MAP_HUGETLB, -1},
+ {PROT_WRITE, MAP_ANONYMOUS | MAP_SHARED | MAP_HUGETLB, -1},
+
+ {PROT_EXEC, MAP_ANONYMOUS | MAP_PRIVATE, -1},
+ {PROT_EXEC, MAP_ANONYMOUS | MAP_SHARED, -1},
+ {PROT_EXEC, MAP_ANONYMOUS | MAP_PRIVATE | MAP_HUGETLB, -1},
+ {PROT_EXEC, MAP_ANONYMOUS | MAP_SHARED | MAP_HUGETLB, -1},
+ {PROT_EXEC, MAP_PRIVATE, 0},
+ {PROT_EXEC, MAP_SHARED, 0},
+
+ {PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, -1},
+ {PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_SHARED, -1},
+ {PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE | MAP_HUGETLB, -1},
+ {PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_SHARED | MAP_HUGETLB, -1},
+ {PROT_READ | PROT_WRITE, MAP_PRIVATE, 0},
+ {PROT_READ | PROT_WRITE, MAP_SHARED, 0},
+
+ {PROT_READ | PROT_WRITE | PROT_EXEC, MAP_ANONYMOUS | MAP_PRIVATE, -1},
+ {PROT_READ | PROT_WRITE | PROT_EXEC, MAP_ANONYMOUS | MAP_SHARED, -1},
+ {PROT_READ | PROT_WRITE | PROT_EXEC, MAP_ANONYMOUS | MAP_PRIVATE | MAP_HUGETLB, -1},
+ {PROT_READ | PROT_WRITE | PROT_EXEC, MAP_ANONYMOUS | MAP_SHARED | MAP_HUGETLB, -1},
+ {PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, 0},
+ {PROT_READ | PROT_WRITE | PROT_EXEC, MAP_SHARED, 0},
+};
+
+static char *flag_to_str(int flags)
+{
+ switch (flags) {
+ case MAP_PRIVATE:
+ return "MAP_PRIVATE";
+ case MAP_SHARED:
+ return "MAP_SHARED";
+ case MAP_ANONYMOUS | MAP_PRIVATE:
+ return "MAP_ANONYMOUS|MAP_PRIVATE";
+ case MAP_ANONYMOUS | MAP_SHARED:
+ return "MAP_ANONYMOUS|MAP_SHARED";
+ case MAP_ANONYMOUS | MAP_PRIVATE | MAP_HUGETLB:
+ return "MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB";
+ case MAP_ANONYMOUS | MAP_SHARED | MAP_HUGETLB:
+ return "MAP_ANONYMOUS|MAP_SHARED|MAP_HUGETLB";
+ default:
+ return "unknown flags";
+ }
+}
+
+static void pkey_test(struct tcase *tc, struct mmap_param *mpa)
+{
+ pid_t pid;
+ char *buffer;
+ int pkey, status;
+ int fd = mpa->fd;
+
+ if (no_hugepage && (mpa->flags & MAP_HUGETLB)) {
+ tst_res(TINFO, "Skip test on (%s) buffer", flag_to_str(mpa->flags));
+ return;
+ }
+
+ if (fd == 0)
+ fd = SAFE_OPEN(TEST_FILE, O_RDWR | O_CREAT, 0664);
+
+ buffer = SAFE_MMAP(NULL, size, mpa->prot, mpa->flags, fd, 0);
+
+ pkey = pkey_alloc(tc->flags, tc->access_rights);
+ if (pkey == -1)
+ tst_brk(TBROK | TERRNO, "pkey_alloc failed");
+
+ tst_res(TINFO, "Set %s on (%s) buffer", tc->name, flag_to_str(mpa->flags));
+ if (pkey_mprotect(buffer, size, mpa->prot, pkey) == -1)
+ tst_brk(TBROK | TERRNO, "pkey_mprotect failed");
+
+ pid = SAFE_FORK();
+ if (pid == 0) {
+ struct rlimit r;
+
+ r.rlim_cur = 1;
+ r.rlim_max = 1;
+ /* Children crash are expected, avoid dumping corefile */
+ SAFE_SETRLIMIT(RLIMIT_CORE, &r);
+
+ switch (tc->access_rights) {
+ case PKEY_DISABLE_ACCESS:
+ tst_res(TFAIL | TERRNO,
+ "Read buffer success, buffer[0] = %d", *buffer);
+ break;
+ case PKEY_DISABLE_WRITE:
+ *buffer = 'a';
+ break;
+ }
+ exit(0);
+ }
+
+ SAFE_WAITPID(pid, &status, 0);
+ if (WIFSIGNALED(status)) {
+ if (WTERMSIG(status) == SIGSEGV) {
+ tst_res(TPASS, "Child ended by %s as expected",
+ tst_strsig(SIGSEGV));
+ } else {
+ tst_res(TFAIL | TERRNO, "Child ended by %s unexpected" ,
+ tst_strsig(WTERMSIG(status)));
+ }
+ } else {
+ tst_res(TFAIL | TERRNO,
+ "Child unexpectedly ended with %d",
+ WEXITSTATUS(status));
+ }
+
+ tst_res(TINFO, "Remove %s from the buffer", tc->name);
+ if (pkey_mprotect(buffer, size, mpa->prot, 0x0) == -1)
+ tst_brk(TBROK | TERRNO, "pkey_mprotect failed");
+
+ switch (mpa->prot) {
+ case PROT_READ:
+ tst_res(TPASS, "Read buffer success, buffer[0] = %d", *buffer);
+ break;
+ case PROT_WRITE:
+ *buffer = 'a';
+ break;
+ case PROT_READ | PROT_WRITE:
+ case PROT_READ | PROT_WRITE | PROT_EXEC:
+ *buffer = 'a';
+ tst_res(TPASS, "Read & Write buffer success, buffer[0] = %d", *buffer);
+ break;
+ }
+
+ if (fd >= 0)
+ SAFE_CLOSE(fd);
+
+ SAFE_MUNMAP(buffer, size);
+
+ if (pkey_free(pkey) == -1)
+ tst_brk(TBROK | TERRNO, "pkey_free failed");
+}
+
+static void verify_pkey(unsigned int i)
+{
+ long unsigned int j;
+ struct mmap_param *mpa;
+
+ struct tcase *tc = &tcases[i];
+
+ for (j = 0; j < ARRAY_SIZE(mmap_params); j++) {
+ mpa = &mmap_params[j];
+
+ pkey_test(tc, mpa);
+ }
+}
+
+static struct tst_test test = {
+ .tcnt = ARRAY_SIZE(tcases),
+ .needs_root = 1,
+ .forks_child = 1,
+ .test = verify_pkey,
+ .setup = setup,
+ .cleanup = cleanup,
+ .save_restore = save_restore,
+};
--
2.20.1