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authorLinus Torvalds <torvalds@linux-foundation.org>2019-07-08 11:42:09 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-07-08 11:42:09 -0700
commit0d37dde70655be73575d011be1bffaf0e3b16ea9 (patch)
tree415c1ee2d66489a032c90039bd8f263821cc3ca7 /tools
parent0902d5011cfaabd6a09326299ef77e1c8735fb89 (diff)
parent7f0a5e0755832301e7b010eab46fb715c483ba60 (diff)
Merge branch 'x86-entry-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 vsyscall updates from Thomas Gleixner: "Further hardening of the legacy vsyscall by providing support for execute only mode and switching the default to it. This prevents a certain class of attacks which rely on the vsyscall page being accessible at a fixed address in the canonical kernel address space" * 'x86-entry-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: selftests/x86: Add a test for process_vm_readv() on the vsyscall page x86/vsyscall: Add __ro_after_init to global variables x86/vsyscall: Change the default vsyscall mode to xonly selftests/x86/vsyscall: Verify that vsyscall=none blocks execution x86/vsyscall: Document odd SIGSEGV error code for vsyscalls x86/vsyscall: Show something useful on a read fault x86/vsyscall: Add a new vsyscall=xonly mode Documentation/admin: Remove the vsyscall=native documentation
Diffstat (limited to 'tools')
-rw-r--r--tools/testing/selftests/x86/test_vsyscall.c120
1 files changed, 95 insertions, 25 deletions
diff --git a/tools/testing/selftests/x86/test_vsyscall.c b/tools/testing/selftests/x86/test_vsyscall.c
index 0b4f1cc2291c..4602326b8f5b 100644
--- a/tools/testing/selftests/x86/test_vsyscall.c
+++ b/tools/testing/selftests/x86/test_vsyscall.c
@@ -18,6 +18,7 @@
#include <sched.h>
#include <stdbool.h>
#include <setjmp.h>
+#include <sys/uio.h>
#ifdef __x86_64__
# define VSYS(x) (x)
@@ -49,21 +50,21 @@ static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
}
/* vsyscalls and vDSO */
-bool should_read_vsyscall = false;
+bool vsyscall_map_r = false, vsyscall_map_x = false;
typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz);
-gtod_t vgtod = (gtod_t)VSYS(0xffffffffff600000);
+const gtod_t vgtod = (gtod_t)VSYS(0xffffffffff600000);
gtod_t vdso_gtod;
typedef int (*vgettime_t)(clockid_t, struct timespec *);
vgettime_t vdso_gettime;
typedef long (*time_func_t)(time_t *t);
-time_func_t vtime = (time_func_t)VSYS(0xffffffffff600400);
+const time_func_t vtime = (time_func_t)VSYS(0xffffffffff600400);
time_func_t vdso_time;
typedef long (*getcpu_t)(unsigned *, unsigned *, void *);
-getcpu_t vgetcpu = (getcpu_t)VSYS(0xffffffffff600800);
+const getcpu_t vgetcpu = (getcpu_t)VSYS(0xffffffffff600800);
getcpu_t vdso_getcpu;
static void init_vdso(void)
@@ -107,7 +108,7 @@ static int init_vsys(void)
maps = fopen("/proc/self/maps", "r");
if (!maps) {
printf("[WARN]\tCould not open /proc/self/maps -- assuming vsyscall is r-x\n");
- should_read_vsyscall = true;
+ vsyscall_map_r = true;
return 0;
}
@@ -133,12 +134,8 @@ static int init_vsys(void)
}
printf("\tvsyscall permissions are %c-%c\n", r, x);
- should_read_vsyscall = (r == 'r');
- if (x != 'x') {
- vgtod = NULL;
- vtime = NULL;
- vgetcpu = NULL;
- }
+ vsyscall_map_r = (r == 'r');
+ vsyscall_map_x = (x == 'x');
found = true;
break;
@@ -148,10 +145,8 @@ static int init_vsys(void)
if (!found) {
printf("\tno vsyscall map in /proc/self/maps\n");
- should_read_vsyscall = false;
- vgtod = NULL;
- vtime = NULL;
- vgetcpu = NULL;
+ vsyscall_map_r = false;
+ vsyscall_map_x = false;
}
return nerrs;
@@ -183,9 +178,13 @@ static inline long sys_getcpu(unsigned * cpu, unsigned * node,
}
static jmp_buf jmpbuf;
+static volatile unsigned long segv_err;
static void sigsegv(int sig, siginfo_t *info, void *ctx_void)
{
+ ucontext_t *ctx = (ucontext_t *)ctx_void;
+
+ segv_err = ctx->uc_mcontext.gregs[REG_ERR];
siglongjmp(jmpbuf, 1);
}
@@ -238,7 +237,7 @@ static int test_gtod(void)
err(1, "syscall gettimeofday");
if (vdso_gtod)
ret_vdso = vdso_gtod(&tv_vdso, &tz_vdso);
- if (vgtod)
+ if (vsyscall_map_x)
ret_vsys = vgtod(&tv_vsys, &tz_vsys);
if (sys_gtod(&tv_sys2, &tz_sys) != 0)
err(1, "syscall gettimeofday");
@@ -252,7 +251,7 @@ static int test_gtod(void)
}
}
- if (vgtod) {
+ if (vsyscall_map_x) {
if (ret_vsys == 0) {
nerrs += check_gtod(&tv_sys1, &tv_sys2, &tz_sys, "vsyscall", &tv_vsys, &tz_vsys);
} else {
@@ -273,7 +272,7 @@ static int test_time(void) {
t_sys1 = sys_time(&t2_sys1);
if (vdso_time)
t_vdso = vdso_time(&t2_vdso);
- if (vtime)
+ if (vsyscall_map_x)
t_vsys = vtime(&t2_vsys);
t_sys2 = sys_time(&t2_sys2);
if (t_sys1 < 0 || t_sys1 != t2_sys1 || t_sys2 < 0 || t_sys2 != t2_sys2) {
@@ -294,7 +293,7 @@ static int test_time(void) {
}
}
- if (vtime) {
+ if (vsyscall_map_x) {
if (t_vsys < 0 || t_vsys != t2_vsys) {
printf("[FAIL]\tvsyscall failed (ret:%ld output:%ld)\n", t_vsys, t2_vsys);
nerrs++;
@@ -330,7 +329,7 @@ static int test_getcpu(int cpu)
ret_sys = sys_getcpu(&cpu_sys, &node_sys, 0);
if (vdso_getcpu)
ret_vdso = vdso_getcpu(&cpu_vdso, &node_vdso, 0);
- if (vgetcpu)
+ if (vsyscall_map_x)
ret_vsys = vgetcpu(&cpu_vsys, &node_vsys, 0);
if (ret_sys == 0) {
@@ -369,7 +368,7 @@ static int test_getcpu(int cpu)
}
}
- if (vgetcpu) {
+ if (vsyscall_map_x) {
if (ret_vsys) {
printf("[FAIL]\tvsyscall getcpu() failed\n");
nerrs++;
@@ -410,20 +409,88 @@ static int test_vsys_r(void)
can_read = false;
}
- if (can_read && !should_read_vsyscall) {
+ if (can_read && !vsyscall_map_r) {
printf("[FAIL]\tWe have read access, but we shouldn't\n");
return 1;
- } else if (!can_read && should_read_vsyscall) {
+ } else if (!can_read && vsyscall_map_r) {
printf("[FAIL]\tWe don't have read access, but we should\n");
return 1;
+ } else if (can_read) {
+ printf("[OK]\tWe have read access\n");
} else {
- printf("[OK]\tgot expected result\n");
+ printf("[OK]\tWe do not have read access: #PF(0x%lx)\n",
+ segv_err);
}
#endif
return 0;
}
+static int test_vsys_x(void)
+{
+#ifdef __x86_64__
+ if (vsyscall_map_x) {
+ /* We already tested this adequately. */
+ return 0;
+ }
+
+ printf("[RUN]\tMake sure that vsyscalls really page fault\n");
+
+ bool can_exec;
+ if (sigsetjmp(jmpbuf, 1) == 0) {
+ vgtod(NULL, NULL);
+ can_exec = true;
+ } else {
+ can_exec = false;
+ }
+
+ if (can_exec) {
+ printf("[FAIL]\tExecuting the vsyscall did not page fault\n");
+ return 1;
+ } else if (segv_err & (1 << 4)) { /* INSTR */
+ printf("[OK]\tExecuting the vsyscall page failed: #PF(0x%lx)\n",
+ segv_err);
+ } else {
+ printf("[FAILT]\tExecution failed with the wrong error: #PF(0x%lx)\n",
+ segv_err);
+ return 1;
+ }
+#endif
+
+ return 0;
+}
+
+static int test_process_vm_readv(void)
+{
+#ifdef __x86_64__
+ char buf[4096];
+ struct iovec local, remote;
+ int ret;
+
+ printf("[RUN]\tprocess_vm_readv() from vsyscall page\n");
+
+ local.iov_base = buf;
+ local.iov_len = 4096;
+ remote.iov_base = (void *)0xffffffffff600000;
+ remote.iov_len = 4096;
+ ret = process_vm_readv(getpid(), &local, 1, &remote, 1, 0);
+ if (ret != 4096) {
+ printf("[OK]\tprocess_vm_readv() failed (ret = %d, errno = %d)\n", ret, errno);
+ return 0;
+ }
+
+ if (vsyscall_map_r) {
+ if (!memcmp(buf, (const void *)0xffffffffff600000, 4096)) {
+ printf("[OK]\tIt worked and read correct data\n");
+ } else {
+ printf("[FAIL]\tIt worked but returned incorrect data\n");
+ return 1;
+ }
+ }
+#endif
+
+ return 0;
+}
#ifdef __x86_64__
#define X86_EFLAGS_TF (1UL << 8)
@@ -455,7 +522,7 @@ static int test_emulation(void)
time_t tmp;
bool is_native;
- if (!vtime)
+ if (!vsyscall_map_x)
return 0;
printf("[RUN]\tchecking that vsyscalls are emulated\n");
@@ -497,6 +564,9 @@ int main(int argc, char **argv)
sethandler(SIGSEGV, sigsegv, 0);
nerrs += test_vsys_r();
+ nerrs += test_vsys_x();
+
+ nerrs += test_process_vm_readv();
#ifdef __x86_64__
nerrs += test_emulation();