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// SPDX-License-Identifier: GPL-2.0+
/*
* Ptrace test for Memory Protection Key registers
*
* Copyright (C) 2015 Anshuman Khandual, IBM Corporation.
* Copyright (C) 2018 IBM Corporation.
*/
#include "ptrace.h"
#include "child.h"
#ifndef __NR_pkey_alloc
#define __NR_pkey_alloc 384
#endif
#ifndef __NR_pkey_free
#define __NR_pkey_free 385
#endif
#ifndef NT_PPC_PKEY
#define NT_PPC_PKEY 0x110
#endif
#ifndef PKEY_DISABLE_EXECUTE
#define PKEY_DISABLE_EXECUTE 0x4
#endif
#define AMR_BITS_PER_PKEY 2
#define PKEY_REG_BITS (sizeof(u64) * 8)
#define pkeyshift(pkey) (PKEY_REG_BITS - ((pkey + 1) * AMR_BITS_PER_PKEY))
static const char user_read[] = "[User Read (Running)]";
static const char user_write[] = "[User Write (Running)]";
static const char ptrace_read_running[] = "[Ptrace Read (Running)]";
static const char ptrace_write_running[] = "[Ptrace Write (Running)]";
/* Information shared between the parent and the child. */
struct shared_info {
struct child_sync child_sync;
/* AMR value the parent expects to read from the child. */
unsigned long amr1;
/* AMR value the parent is expected to write to the child. */
unsigned long amr2;
/* AMR value that ptrace should refuse to write to the child. */
unsigned long amr3;
/* IAMR value the parent expects to read from the child. */
unsigned long expected_iamr;
/* UAMOR value the parent expects to read from the child. */
unsigned long expected_uamor;
/*
* IAMR and UAMOR values that ptrace should refuse to write to the child
* (even though they're valid ones) because userspace doesn't have
* access to those registers.
*/
unsigned long new_iamr;
unsigned long new_uamor;
};
static int sys_pkey_alloc(unsigned long flags, unsigned long init_access_rights)
{
return syscall(__NR_pkey_alloc, flags, init_access_rights);
}
static int sys_pkey_free(int pkey)
{
return syscall(__NR_pkey_free, pkey);
}
static int child(struct shared_info *info)
{
unsigned long reg;
bool disable_execute = true;
int pkey1, pkey2, pkey3;
int ret;
/* Wait until parent fills out the initial register values. */
ret = wait_parent(&info->child_sync);
if (ret)
return ret;
/* Get some pkeys so that we can change their bits in the AMR. */
pkey1 = sys_pkey_alloc(0, PKEY_DISABLE_EXECUTE);
if (pkey1 < 0) {
pkey1 = sys_pkey_alloc(0, 0);
CHILD_FAIL_IF(pkey1 < 0, &info->child_sync);
disable_execute = false;
}
pkey2 = sys_pkey_alloc(0, 0);
CHILD_FAIL_IF(pkey2 < 0, &info->child_sync);
pkey3 = sys_pkey_alloc(0, 0);
CHILD_FAIL_IF(pkey3 < 0, &info->child_sync);
info->amr1 |= 3ul << pkeyshift(pkey1);
info->amr2 |= 3ul << pkeyshift(pkey2);
info->amr3 |= info->amr2 | 3ul << pkeyshift(pkey3);
if (disable_execute)
info->expected_iamr |= 1ul << pkeyshift(pkey1);
else
info->expected_iamr &= ~(1ul << pkeyshift(pkey1));
info->expected_iamr &= ~(1ul << pkeyshift(pkey2) | 1ul << pkeyshift(pkey3));
info->expected_uamor |= 3ul << pkeyshift(pkey1) |
3ul << pkeyshift(pkey2);
info->new_iamr |= 1ul << pkeyshift(pkey1) | 1ul << pkeyshift(pkey2);
info->new_uamor |= 3ul << pkeyshift(pkey1);
/*
* We won't use pkey3. We just want a plausible but invalid key to test
* whether ptrace will let us write to AMR bits we are not supposed to.
*
* This also tests whether the kernel restores the UAMOR permissions
* after a key is freed.
*/
sys_pkey_free(pkey3);
printf("%-30s AMR: %016lx pkey1: %d pkey2: %d pkey3: %d\n",
user_write, info->amr1, pkey1, pkey2, pkey3);
set_amr(info->amr1);
/* Wait for parent to read our AMR value and write a new one. */
ret = prod_parent(&info->child_sync);
CHILD_FAIL_IF(ret, &info->child_sync);
ret = wait_parent(&info->child_sync);
if (ret)
return ret;
reg = mfspr(SPRN_AMR);
printf("%-30s AMR: %016lx\n", user_read, reg);
CHILD_FAIL_IF(reg != info->amr2, &info->child_sync);
/*
* Wait for parent to try to write an invalid AMR value.
*/
ret = prod_parent(&info->child_sync);
CHILD_FAIL_IF(ret, &info->child_sync);
ret = wait_parent(&info->child_sync);
if (ret)
return ret;
reg = mfspr(SPRN_AMR);
printf("%-30s AMR: %016lx\n", user_read, reg);
CHILD_FAIL_IF(reg != info->amr2, &info->child_sync);
/*
* Wait for parent to try to write an IAMR and a UAMOR value. We can't
* verify them, but we can verify that the AMR didn't change.
*/
ret = prod_parent(&info->child_sync);
CHILD_FAIL_IF(ret, &info->child_sync);
ret = wait_parent(&info->child_sync);
if (ret)
return ret;
reg = mfspr(SPRN_AMR);
printf("%-30s AMR: %016lx\n", user_read, reg);
CHILD_FAIL_IF(reg != info->amr2, &info->child_sync);
/* Now let parent now that we are finished. */
ret = prod_parent(&info->child_sync);
CHILD_FAIL_IF(ret, &info->child_sync);
return TEST_PASS;
}
static int parent(struct shared_info *info, pid_t pid)
{
unsigned long regs[3];
int ret, status;
/*
* Get the initial values for AMR, IAMR and UAMOR and communicate them
* to the child.
*/
ret = ptrace_read_regs(pid, NT_PPC_PKEY, regs, 3);
PARENT_SKIP_IF_UNSUPPORTED(ret, &info->child_sync);
PARENT_FAIL_IF(ret, &info->child_sync);
info->amr1 = info->amr2 = info->amr3 = regs[0];
info->expected_iamr = info->new_iamr = regs[1];
info->expected_uamor = info->new_uamor = regs[2];
/* Wake up child so that it can set itself up. */
ret = prod_child(&info->child_sync);
PARENT_FAIL_IF(ret, &info->child_sync);
ret = wait_child(&info->child_sync);
if (ret)
return ret;
/* Verify that we can read the pkey registers from the child. */
ret = ptrace_read_regs(pid, NT_PPC_PKEY, regs, 3);
PARENT_FAIL_IF(ret, &info->child_sync);
printf("%-30s AMR: %016lx IAMR: %016lx UAMOR: %016lx\n",
ptrace_read_running, regs[0], regs[1], regs[2]);
PARENT_FAIL_IF(regs[0] != info->amr1, &info->child_sync);
PARENT_FAIL_IF(regs[1] != info->expected_iamr, &info->child_sync);
PARENT_FAIL_IF(regs[2] != info->expected_uamor, &info->child_sync);
/* Write valid AMR value in child. */
ret = ptrace_write_regs(pid, NT_PPC_PKEY, &info->amr2, 1);
PARENT_FAIL_IF(ret, &info->child_sync);
printf("%-30s AMR: %016lx\n", ptrace_write_running, info->amr2);
/* Wake up child so that it can verify it changed. */
ret = prod_child(&info->child_sync);
PARENT_FAIL_IF(ret, &info->child_sync);
ret = wait_child(&info->child_sync);
if (ret)
return ret;
/* Write invalid AMR value in child. */
ret = ptrace_write_regs(pid, NT_PPC_PKEY, &info->amr3, 1);
PARENT_FAIL_IF(ret, &info->child_sync);
printf("%-30s AMR: %016lx\n", ptrace_write_running, info->amr3);
/* Wake up child so that it can verify it didn't change. */
ret = prod_child(&info->child_sync);
PARENT_FAIL_IF(ret, &info->child_sync);
ret = wait_child(&info->child_sync);
if (ret)
return ret;
/* Try to write to IAMR. */
regs[0] = info->amr1;
regs[1] = info->new_iamr;
ret = ptrace_write_regs(pid, NT_PPC_PKEY, regs, 2);
PARENT_FAIL_IF(!ret, &info->child_sync);
printf("%-30s AMR: %016lx IAMR: %016lx\n",
ptrace_write_running, regs[0], regs[1]);
/* Try to write to IAMR and UAMOR. */
regs[2] = info->new_uamor;
ret = ptrace_write_regs(pid, NT_PPC_PKEY, regs, 3);
PARENT_FAIL_IF(!ret, &info->child_sync);
printf("%-30s AMR: %016lx IAMR: %016lx UAMOR: %016lx\n",
ptrace_write_running, regs[0], regs[1], regs[2]);
/* Verify that all registers still have their expected values. */
ret = ptrace_read_regs(pid, NT_PPC_PKEY, regs, 3);
PARENT_FAIL_IF(ret, &info->child_sync);
printf("%-30s AMR: %016lx IAMR: %016lx UAMOR: %016lx\n",
ptrace_read_running, regs[0], regs[1], regs[2]);
PARENT_FAIL_IF(regs[0] != info->amr2, &info->child_sync);
PARENT_FAIL_IF(regs[1] != info->expected_iamr, &info->child_sync);
PARENT_FAIL_IF(regs[2] != info->expected_uamor, &info->child_sync);
/* Wake up child so that it can verify AMR didn't change and wrap up. */
ret = prod_child(&info->child_sync);
PARENT_FAIL_IF(ret, &info->child_sync);
ret = wait(&status);
if (ret != pid) {
printf("Child's exit status not captured\n");
ret = TEST_PASS;
} else if (!WIFEXITED(status)) {
printf("Child exited abnormally\n");
ret = TEST_FAIL;
} else
ret = WEXITSTATUS(status) ? TEST_FAIL : TEST_PASS;
return ret;
}
static int ptrace_pkey(void)
{
struct shared_info *info;
int shm_id;
int ret;
pid_t pid;
shm_id = shmget(IPC_PRIVATE, sizeof(*info), 0777 | IPC_CREAT);
info = shmat(shm_id, NULL, 0);
ret = init_child_sync(&info->child_sync);
if (ret)
return ret;
pid = fork();
if (pid < 0) {
perror("fork() failed");
ret = TEST_FAIL;
} else if (pid == 0)
ret = child(info);
else
ret = parent(info, pid);
shmdt(info);
if (pid) {
destroy_child_sync(&info->child_sync);
shmctl(shm_id, IPC_RMID, NULL);
}
return ret;
}
int main(int argc, char *argv[])
{
return test_harness(ptrace_pkey, "ptrace_pkey");
}
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