/*
* Copyright (c) 1991, 1992 Paul Kranenburg <pk@cs.few.eur.nl>
* Copyright (c) 1993 Branko Lankester <branko@hacktic.nl>
* Copyright (c) 1993, 1994, 1995, 1996 Rick Sladkey <jrs@world.std.com>
* Copyright (c) 1996-1999 Wichert Akkerman <wichert@cistron.nl>
* Copyright (c) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
* Linux for s390 port by D.J. Barrow
* <barrow_dj@mail.yahoo.com,djbarrow@de.ibm.com>
* Copyright (c) 1999-2017 The strace developers.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "defs.h"
#include <sys/uio.h>
#include <asm/unistd.h>
#include "scno.h"
#include "ptrace.h"
static bool process_vm_readv_not_supported;
#ifndef HAVE_PROCESS_VM_READV
/*
* Need to do this since process_vm_readv() is not yet available in libc.
* When libc is updated, only "static bool process_vm_readv_not_supported"
* line remains.
* The name is different to avoid potential collision with OS headers.
*/
static ssize_t strace_process_vm_readv(pid_t pid,
const struct iovec *lvec,
unsigned long liovcnt,
const struct iovec *rvec,
unsigned long riovcnt,
unsigned long flags)
{
return syscall(__NR_process_vm_readv,
(long) pid, lvec, liovcnt, rvec, riovcnt, flags);
}
# define process_vm_readv strace_process_vm_readv
#endif /* !HAVE_PROCESS_VM_READV */
static ssize_t
vm_read_mem(const pid_t pid, void *const laddr,
const kernel_ulong_t raddr, const size_t len)
{
const unsigned long truncated_raddr = raddr;
#if SIZEOF_LONG < SIZEOF_KERNEL_LONG_T
if (raddr != (kernel_ulong_t) truncated_raddr) {
errno = EIO;
return -1;
}
#endif
const struct iovec local = {
.iov_base = laddr,
.iov_len = len
};
const struct iovec remote = {
.iov_base = (void *) truncated_raddr,
.iov_len = len
};
const ssize_t rc = process_vm_readv(pid, &local, 1, &remote, 1, 0);
if (rc < 0 && errno == ENOSYS)
process_vm_readv_not_supported = true;
return rc;
}
static bool
tracee_addr_is_invalid(kernel_ulong_t addr)
{
return
#if ANY_WORDSIZE_LESS_THAN_KERNEL_LONG
current_wordsize < sizeof(addr) && addr & ~(kernel_ulong_t) -1U;
#else
false;
#endif
}
/* legacy method of copying from tracee */
static int
umoven_peekdata(const int pid, kernel_ulong_t addr, unsigned int len,
void *laddr)
{
unsigned int nread = 0;
unsigned int residue = addr & (sizeof(long) - 1);
while (len) {
addr &= -sizeof(long); /* aligned address */
errno = 0;
union {
long val;
char x[sizeof(long)];
} u = { .val = ptrace(PTRACE_PEEKDATA, pid, addr, 0) };
switch (errno) {
case 0:
break;
case ESRCH: case EINVAL:
/* these could be seen if the process is gone */
return -1;
case EFAULT: case EIO: case EPERM:
/* address space is inaccessible */
if (nread) {
perror_msg("umoven: short read (%u < %u) @0x%" PRI_klx,
nread, nread + len, addr - nread);
}
return -1;
default:
/* all the rest is strange and should be reported */
perror_msg("umoven: PTRACE_PEEKDATA pid:%d @0x%" PRI_klx,
pid, addr);
return -1;
}
unsigned int m = MIN(sizeof(long) - residue, len);
memcpy(laddr, &u.x[residue], m);
residue = 0;
addr += sizeof(long);
laddr += m;
nread += m;
len -= m;
}
return 0;
}
/*
* Copy `len' bytes of data from process `pid'
* at address `addr' to our space at `our_addr'.
*/
int
umoven(struct tcb *const tcp, kernel_ulong_t addr, unsigned int len,
void *const our_addr)
{
if (tracee_addr_is_invalid(addr))
return -1;
const int pid = tcp->pid;
if (process_vm_readv_not_supported)
return umoven_peekdata(pid, addr, len, our_addr);
int r = vm_read_mem(pid, our_addr, addr, len);
if ((unsigned int) r == len)
return 0;
if (r >= 0) {
error_msg("umoven: short read (%u < %u) @0x%" PRI_klx,
(unsigned int) r, len, addr);
return -1;
}
switch (errno) {
case ENOSYS:
case EPERM:
/* try PTRACE_PEEKDATA */
return umoven_peekdata(pid, addr, len, our_addr);
case ESRCH:
/* the process is gone */
return -1;
case EFAULT: case EIO:
/* address space is inaccessible */
return -1;
default:
/* all the rest is strange and should be reported */
perror_msg("process_vm_readv: pid:%d @0x%" PRI_klx,
pid, addr);
return -1;
}
}
/*
* Like umoven_peekdata but make the additional effort of looking
* for a terminating zero byte.
*/
static int
umovestr_peekdata(const int pid, kernel_ulong_t addr, unsigned int len,
void *laddr)
{
unsigned int nread = 0;
unsigned int residue = addr & (sizeof(long) - 1);
void *const orig_addr = laddr;
while (len) {
addr &= -sizeof(long); /* aligned address */
errno = 0;
union {
unsigned long val;
char x[sizeof(long)];
} u = { .val = ptrace(PTRACE_PEEKDATA, pid, addr, 0) };
switch (errno) {
case 0:
break;
case ESRCH: case EINVAL:
/* these could be seen if the process is gone */
return -1;
case EFAULT: case EIO: case EPERM:
/* address space is inaccessible */
if (nread) {
perror_msg("umovestr: short read (%d < %d) @0x%" PRI_klx,
nread, nread + len, addr - nread);
}
return -1;
default:
/* all the rest is strange and should be reported */
perror_msg("umovestr: PTRACE_PEEKDATA pid:%d @0x%" PRI_klx,
pid, addr);
return -1;
}
unsigned int m = MIN(sizeof(long) - residue, len);
memcpy(laddr, &u.x[residue], m);
while (residue < sizeof(long))
if (u.x[residue++] == '\0')
return (laddr - orig_addr) + residue;
residue = 0;
addr += sizeof(long);
laddr += m;
nread += m;
len -= m;
}
return 0;
}
/*
* Like `umove' but make the additional effort of looking
* for a terminating zero byte.
*
* Returns < 0 on error, strlen + 1 if NUL was seen,
* else 0 if len bytes were read but no NUL byte seen.
*
* Note: there is no guarantee we won't overwrite some bytes
* in laddr[] _after_ terminating NUL (but, of course,
* we never write past laddr[len-1]).
*/
int
umovestr(struct tcb *const tcp, kernel_ulong_t addr, unsigned int len,
char *laddr)
{
if (tracee_addr_is_invalid(addr))
return -1;
const int pid = tcp->pid;
if (process_vm_readv_not_supported)
return umovestr_peekdata(pid, addr, len, laddr);
const size_t page_size = get_pagesize();
const size_t page_mask = page_size - 1;
unsigned int nread = 0;
while (len) {
/*
* Don't cross pages, otherwise we can get EFAULT
* and fail to notice that terminating NUL lies
* in the existing (first) page.
*/
unsigned int chunk_len = len > page_size ? page_size : len;
unsigned int end_in_page = (addr + chunk_len) & page_mask;
if (chunk_len > end_in_page) /* crosses to the next page */
chunk_len -= end_in_page;
int r = vm_read_mem(pid, laddr, addr, chunk_len);
if (r > 0) {
char *nul_addr = memchr(laddr, '\0', r);
if (nul_addr)
return (nul_addr - laddr) + 1;
addr += r;
laddr += r;
nread += r;
len -= r;
continue;
}
switch (errno) {
case ENOSYS:
case EPERM:
/* try PTRACE_PEEKDATA */
if (!nread)
return umovestr_peekdata(pid, addr,
len, laddr);
/* fall through */
case EFAULT: case EIO:
/* address space is inaccessible */
if (nread)
perror_msg("umovestr: short read (%d < %d) @0x%" PRI_klx,
nread, nread + len, addr - nread);
return -1;
case ESRCH:
/* the process is gone */
return -1;
default:
/* all the rest is strange and should be reported */
perror_msg("process_vm_readv: pid:%d @0x%" PRI_klx,
pid, addr);
return -1;
}
}
return 0;
}