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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2021 Benjamin Berg <benjamin@sipsolutions.net>
* Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
*/
#include <stddef.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/mman.h>
#include <init.h>
#include <as-layout.h>
#include <mm_id.h>
#include <os.h>
#include <ptrace_user.h>
#include <registers.h>
#include <skas.h>
#include <sysdep/ptrace.h>
#include <sysdep/stub.h>
#include "../internal.h"
extern char __syscall_stub_start[];
void syscall_stub_dump_error(struct mm_id *mm_idp)
{
struct stub_data *proc_data = (void *)mm_idp->stack;
struct stub_syscall *sc;
if (proc_data->syscall_data_len < 0 ||
proc_data->syscall_data_len >= ARRAY_SIZE(proc_data->syscall_data))
panic("Syscall data was corrupted by stub (len is: %d, expected maximum: %d)!",
proc_data->syscall_data_len,
mm_idp->syscall_data_len);
sc = &proc_data->syscall_data[proc_data->syscall_data_len];
printk(UM_KERN_ERR "%s : length = %d, last offset = %d",
__func__, mm_idp->syscall_data_len,
proc_data->syscall_data_len);
printk(UM_KERN_ERR "%s : stub syscall type %d failed, return value = 0x%lx\n",
__func__, sc->syscall, proc_data->err);
print_hex_dump(UM_KERN_ERR, " syscall data: ", 0,
16, 4, sc, sizeof(*sc), 0);
}
static inline unsigned long *check_init_stack(struct mm_id * mm_idp,
unsigned long *stack)
{
if (stack == NULL) {
stack = (unsigned long *) mm_idp->stack + 2;
*stack = 0;
}
return stack;
}
static unsigned long syscall_regs[MAX_REG_NR];
static int __init init_syscall_regs(void)
{
get_safe_registers(syscall_regs, NULL);
syscall_regs[REGS_IP_INDEX] = STUB_CODE +
((unsigned long) stub_syscall_handler -
(unsigned long) __syscall_stub_start);
syscall_regs[REGS_SP_INDEX] = STUB_DATA +
offsetof(struct stub_data, sigstack) +
sizeof(((struct stub_data *) 0)->sigstack) -
sizeof(void *);
return 0;
}
__initcall(init_syscall_regs);
static inline long do_syscall_stub(struct mm_id *mm_idp)
{
struct stub_data *proc_data = (void *)mm_idp->stack;
int n, i;
int err, pid = mm_idp->u.pid;
n = ptrace_setregs(pid, syscall_regs);
if (n < 0) {
printk(UM_KERN_ERR "Registers - \n");
for (i = 0; i < MAX_REG_NR; i++)
printk(UM_KERN_ERR "\t%d\t0x%lx\n", i, syscall_regs[i]);
panic("%s : PTRACE_SETREGS failed, errno = %d\n",
__func__, -n);
}
/* Inform process how much we have filled in. */
proc_data->syscall_data_len = mm_idp->syscall_data_len;
err = ptrace(PTRACE_CONT, pid, 0, 0);
if (err)
panic("Failed to continue stub, pid = %d, errno = %d\n", pid,
errno);
wait_stub_done(pid);
/*
* proc_data->err will be non-zero if there was an (unexpected) error.
* In that case, syscall_data_len points to the last executed syscall,
* otherwise it will be zero (but we do not need to rely on that).
*/
if (proc_data->err < 0) {
syscall_stub_dump_error(mm_idp);
/* Store error code in case someone tries to add more syscalls */
mm_idp->syscall_data_len = proc_data->err;
} else {
mm_idp->syscall_data_len = 0;
}
return mm_idp->syscall_data_len;
}
int syscall_stub_flush(struct mm_id *mm_idp)
{
int res;
if (mm_idp->syscall_data_len == 0)
return 0;
/* If an error happened already, report it and reset the state. */
if (mm_idp->syscall_data_len < 0) {
res = mm_idp->syscall_data_len;
mm_idp->syscall_data_len = 0;
return res;
}
res = do_syscall_stub(mm_idp);
mm_idp->syscall_data_len = 0;
return res;
}
struct stub_syscall *syscall_stub_alloc(struct mm_id *mm_idp)
{
struct stub_syscall *sc;
struct stub_data *proc_data = (struct stub_data *) mm_idp->stack;
if (mm_idp->syscall_data_len > 0 &&
mm_idp->syscall_data_len == ARRAY_SIZE(proc_data->syscall_data))
do_syscall_stub(mm_idp);
if (mm_idp->syscall_data_len < 0) {
/* Return dummy to retain error state. */
sc = &proc_data->syscall_data[0];
} else {
sc = &proc_data->syscall_data[mm_idp->syscall_data_len];
mm_idp->syscall_data_len += 1;
}
memset(sc, 0, sizeof(*sc));
return sc;
}
static struct stub_syscall *syscall_stub_get_previous(struct mm_id *mm_idp,
int syscall_type,
unsigned long virt)
{
if (mm_idp->syscall_data_len > 0) {
struct stub_data *proc_data = (void *) mm_idp->stack;
struct stub_syscall *sc;
sc = &proc_data->syscall_data[mm_idp->syscall_data_len - 1];
if (sc->syscall == syscall_type &&
sc->mem.addr + sc->mem.length == virt)
return sc;
}
return NULL;
}
void map(struct mm_id *mm_idp, unsigned long virt, unsigned long len, int prot,
int phys_fd, unsigned long long offset)
{
struct stub_syscall *sc;
/* Compress with previous syscall if that is possible */
sc = syscall_stub_get_previous(mm_idp, STUB_SYSCALL_MMAP, virt);
if (sc && sc->mem.prot == prot && sc->mem.fd == phys_fd &&
sc->mem.offset == MMAP_OFFSET(offset - sc->mem.length)) {
sc->mem.length += len;
return;
}
sc = syscall_stub_alloc(mm_idp);
sc->syscall = STUB_SYSCALL_MMAP;
sc->mem.addr = virt;
sc->mem.length = len;
sc->mem.prot = prot;
sc->mem.fd = phys_fd;
sc->mem.offset = MMAP_OFFSET(offset);
}
void unmap(struct mm_id *mm_idp, unsigned long addr, unsigned long len)
{
struct stub_syscall *sc;
/* Compress with previous syscall if that is possible */
sc = syscall_stub_get_previous(mm_idp, STUB_SYSCALL_MUNMAP, addr);
if (sc) {
sc->mem.length += len;
return;
}
sc = syscall_stub_alloc(mm_idp);
sc->syscall = STUB_SYSCALL_MUNMAP;
sc->mem.addr = addr;
sc->mem.length = len;
}
void protect(struct mm_id *mm_idp, unsigned long addr, unsigned long len,
unsigned int prot)
{
struct stub_syscall *sc;
/* Compress with previous syscall if that is possible */
sc = syscall_stub_get_previous(mm_idp, STUB_SYSCALL_MPROTECT, addr);
if (sc && sc->mem.prot == prot) {
sc->mem.length += len;
return;
}
sc = syscall_stub_alloc(mm_idp);
sc->syscall = STUB_SYSCALL_MPROTECT;
sc->mem.addr = addr;
sc->mem.length = len;
sc->mem.prot = prot;
}
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