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qemu/linux-user/flatload.c
Philippe Mathieu-Daudé a9ee641bd4 linux-user/flatload: Take mmap_lock in load_flt_binary() 
load_flt_binary() calls load_flat_file() -> page_set_flags().

page_set_flags() must be called with the mmap_lock held,
otherwise it aborts:

  $ qemu-arm -L stm32/lib/ stm32/bin/busybox
  qemu-arm: ../accel/tcg/user-exec.c:505: page_set_flags: Assertion `have_mmap_lock()' failed.
  Aborted (core dumped)

Fix by taking the lock in load_flt_binary().

Fixes: fbd3c4cff6 ("linux-user/arm: Mark the commpage executable")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2525
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20240822095045.72643-3-philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2024-10-08 06:28:46 -07:00

556 lines
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/****************************************************************************/
/*
* QEMU bFLT binary loader. Based on linux/fs/binfmt_flat.c
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*
* Copyright (C) 2006 CodeSourcery.
* Copyright (C) 2000-2003 David McCullough <davidm@snapgear.com>
* Copyright (C) 2002 Greg Ungerer <gerg@snapgear.com>
* Copyright (C) 2002 SnapGear, by Paul Dale <pauli@snapgear.com>
* Copyright (C) 2000, 2001 Lineo, by David McCullough <davidm@lineo.com>
* based heavily on:
*
* linux/fs/binfmt_aout.c:
* Copyright (C) 1991, 1992, 1996 Linus Torvalds
* linux/fs/binfmt_flat.c for 2.0 kernel
* Copyright (C) 1998 Kenneth Albanowski <kjahds@kjahds.com>
* JAN/99 -- coded full program relocation (gerg@snapgear.com)
*/
/****************************************************************************/
#include "qemu/osdep.h"
#include "qemu.h"
#include "user-internals.h"
#include "loader.h"
#include "user-mmap.h"
#include "flat.h"
#include "target_flat.h"
//#define DEBUG
#ifdef DEBUG
#define DBG_FLT(...) printf(__VA_ARGS__)
#else
#define DBG_FLT(...)
#endif
#define RELOC_FAILED 0xff00ff01 /* Relocation incorrect somewhere */
#define UNLOADED_LIB 0x7ff000ff /* Placeholder for unused library */
struct lib_info {
abi_ulong start_code; /* Start of text segment */
abi_ulong start_data; /* Start of data segment */
abi_ulong end_data; /* Start of bss section */
abi_ulong start_brk; /* End of data segment */
abi_ulong text_len; /* Length of text segment */
abi_ulong entry; /* Start address for this module */
abi_ulong build_date; /* When this one was compiled */
short loaded; /* Has this library been loaded? */
};
struct linux_binprm;
/****************************************************************************/
/*
* create_flat_tables() parses the env- and arg-strings in new user
* memory and creates the pointer tables from them, and puts their
* addresses on the "stack", returning the new stack pointer value.
*/
/* Push a block of strings onto the guest stack. */
static abi_ulong copy_strings(abi_ulong p, int n, char **s)
{
int len;
while (n-- > 0) {
len = strlen(s[n]) + 1;
p -= len;
memcpy_to_target(p, s[n], len);
}
return p;
}
static int target_pread(int fd, abi_ulong ptr, abi_ulong len,
abi_ulong offset)
{
void *buf;
int ret;
buf = lock_user(VERIFY_WRITE, ptr, len, 0);
if (!buf) {
return -EFAULT;
}
ret = pread(fd, buf, len, offset);
if (ret < 0) {
ret = -errno;
}
unlock_user(buf, ptr, len);
return ret;
}
/****************************************************************************/
static abi_ulong
calc_reloc(abi_ulong r, struct lib_info *p, int curid, int internalp)
{
abi_ulong addr;
int id;
abi_ulong start_brk;
abi_ulong start_data;
abi_ulong text_len;
abi_ulong start_code;
id = 0;
start_brk = p[id].start_brk;
start_data = p[id].start_data;
start_code = p[id].start_code;
text_len = p[id].text_len;
if (!flat_reloc_valid(r, start_brk - start_data + text_len)) {
fprintf(stderr, "BINFMT_FLAT: reloc outside program 0x%x "
"(0 - 0x%x/0x%x)\n",
(int) r,(int)(start_brk-start_code),(int)text_len);
goto failed;
}
if (r < text_len) /* In text segment */
addr = r + start_code;
else /* In data segment */
addr = r - text_len + start_data;
/* Range checked already above so doing the range tests is redundant...*/
return(addr);
failed:
abort();
return RELOC_FAILED;
}
/****************************************************************************/
/* ??? This does not handle endianness correctly. */
static void old_reloc(struct lib_info *libinfo, uint32_t rl)
{
#ifdef DEBUG
const char *segment[] = { "TEXT", "DATA", "BSS", "*UNKNOWN*" };
#endif
uint32_t *ptr;
uint32_t offset;
int reloc_type;
offset = rl & 0x3fffffff;
reloc_type = rl >> 30;
/* ??? How to handle this? */
#if defined(CONFIG_COLDFIRE)
ptr = (uint32_t *) ((unsigned long) libinfo->start_code + offset);
#else
ptr = (uint32_t *) ((unsigned long) libinfo->start_data + offset);
#endif
#ifdef DEBUG
fprintf(stderr, "Relocation of variable at DATASEG+%x "
"(address %p, currently %x) into segment %s\n",
offset, ptr, (int)*ptr, segment[reloc_type]);
#endif
switch (reloc_type) {
case OLD_FLAT_RELOC_TYPE_TEXT:
*ptr += libinfo->start_code;
break;
case OLD_FLAT_RELOC_TYPE_DATA:
*ptr += libinfo->start_data;
break;
case OLD_FLAT_RELOC_TYPE_BSS:
*ptr += libinfo->end_data;
break;
default:
fprintf(stderr, "BINFMT_FLAT: Unknown relocation type=%x\n",
reloc_type);
break;
}
DBG_FLT("Relocation became %x\n", (int)*ptr);
}
/****************************************************************************/
static int load_flat_file(struct linux_binprm * bprm,
struct lib_info *libinfo, int id, abi_ulong *extra_stack)
{
struct flat_hdr * hdr;
abi_ulong textpos = 0, datapos = 0;
abi_long result;
abi_ulong realdatastart = 0;
abi_ulong text_len, data_len, bss_len, stack_len, flags;
abi_ulong extra;
abi_ulong reloc = 0, rp;
int i, rev, relocs = 0;
abi_ulong fpos;
abi_ulong start_code;
abi_ulong indx_len;
hdr = ((struct flat_hdr *) bprm->buf); /* exec-header */
text_len = ntohl(hdr->data_start);
data_len = ntohl(hdr->data_end) - ntohl(hdr->data_start);
bss_len = ntohl(hdr->bss_end) - ntohl(hdr->data_end);
stack_len = ntohl(hdr->stack_size);
if (extra_stack) {
stack_len += *extra_stack;
*extra_stack = stack_len;
}
relocs = ntohl(hdr->reloc_count);
flags = ntohl(hdr->flags);
rev = ntohl(hdr->rev);
DBG_FLT("BINFMT_FLAT: Loading file: %s\n", bprm->filename);
if (rev != FLAT_VERSION && rev != OLD_FLAT_VERSION) {
fprintf(stderr, "BINFMT_FLAT: bad magic/rev (0x%x, need 0x%x)\n",
rev, (int) FLAT_VERSION);
return -ENOEXEC;
}
/* Don't allow old format executables to use shared libraries */
if (rev == OLD_FLAT_VERSION && id != 0) {
fprintf(stderr, "BINFMT_FLAT: shared libraries are not available\n");
return -ENOEXEC;
}
/*
* fix up the flags for the older format, there were all kinds
* of endian hacks, this only works for the simple cases
*/
if (rev == OLD_FLAT_VERSION && flat_old_ram_flag(flags))
flags = FLAT_FLAG_RAM;
if (flags & (FLAT_FLAG_GZIP|FLAT_FLAG_GZDATA)) {
fprintf(stderr, "ZFLAT executables are not supported\n");
return -ENOEXEC;
}
/*
* calculate the extra space we need to map in
*/
extra = relocs * sizeof(abi_ulong);
if (extra < bss_len + stack_len)
extra = bss_len + stack_len;
/* Add space for library base pointers. Make sure this does not
misalign the doesn't misalign the data segment. */
indx_len = MAX_SHARED_LIBS * sizeof(abi_ulong);
indx_len = (indx_len + 15) & ~(abi_ulong)15;
/*
* Allocate the address space.
*/
probe_guest_base(bprm->filename, 0,
text_len + data_len + extra + indx_len - 1);
/*
* there are a couple of cases here, the separate code/data
* case, and then the fully copied to RAM case which lumps
* it all together.
*/
if ((flags & (FLAT_FLAG_RAM|FLAT_FLAG_GZIP)) == 0) {
/*
* this should give us a ROM ptr, but if it doesn't we don't
* really care
*/
DBG_FLT("BINFMT_FLAT: ROM mapping of file (we hope)\n");
textpos = target_mmap(0, text_len, PROT_READ|PROT_EXEC,
MAP_PRIVATE, bprm->src.fd, 0);
if (textpos == -1) {
fprintf(stderr, "Unable to mmap process text\n");
return -1;
}
realdatastart = target_mmap(0, data_len + extra + indx_len,
PROT_READ|PROT_WRITE|PROT_EXEC,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (realdatastart == -1) {
fprintf(stderr, "Unable to allocate RAM for process data\n");
return realdatastart;
}
datapos = realdatastart + indx_len;
DBG_FLT("BINFMT_FLAT: Allocated data+bss+stack (%d bytes): %x\n",
(int)(data_len + bss_len + stack_len), (int)datapos);
fpos = ntohl(hdr->data_start);
result = target_pread(bprm->src.fd, datapos,
data_len + (relocs * sizeof(abi_ulong)),
fpos);
if (result < 0) {
fprintf(stderr, "Unable to read data+bss\n");
return result;
}
reloc = datapos + (ntohl(hdr->reloc_start) - text_len);
} else {
textpos = target_mmap(0, text_len + data_len + extra + indx_len,
PROT_READ | PROT_EXEC | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (textpos == -1 ) {
fprintf(stderr, "Unable to allocate RAM for process text/data\n");
return -1;
}
realdatastart = textpos + ntohl(hdr->data_start);
datapos = realdatastart + indx_len;
reloc = (textpos + ntohl(hdr->reloc_start) + indx_len);
result = target_pread(bprm->src.fd, textpos,
text_len, 0);
if (result >= 0) {
result = target_pread(bprm->src.fd, datapos,
data_len + (relocs * sizeof(abi_ulong)),
ntohl(hdr->data_start));
}
if (result < 0) {
fprintf(stderr, "Unable to read code+data+bss\n");
return result;
}
}
DBG_FLT("Mapping is 0x%x, Entry point is 0x%x, data_start is 0x%x\n",
(int)textpos, 0x00ffffff&ntohl(hdr->entry),
ntohl(hdr->data_start));
/* The main program needs a little extra setup in the task structure */
start_code = textpos + sizeof (struct flat_hdr);
DBG_FLT("%s %s: TEXT=%x-%x DATA=%x-%x BSS=%x-%x\n",
id ? "Lib" : "Load", bprm->filename,
(int) start_code, (int) (textpos + text_len),
(int) datapos,
(int) (datapos + data_len),
(int) (datapos + data_len),
(int) (((datapos + data_len + bss_len) + 3) & ~3));
text_len -= sizeof(struct flat_hdr); /* the real code len */
/* Store the current module values into the global library structure */
libinfo[id].start_code = start_code;
libinfo[id].start_data = datapos;
libinfo[id].end_data = datapos + data_len;
libinfo[id].start_brk = datapos + data_len + bss_len;
libinfo[id].text_len = text_len;
libinfo[id].loaded = 1;
libinfo[id].entry = (0x00ffffff & ntohl(hdr->entry)) + textpos;
libinfo[id].build_date = ntohl(hdr->build_date);
/*
* We just load the allocations into some temporary memory to
* help simplify all this mumbo jumbo
*
* We've got two different sections of relocation entries.
* The first is the GOT which resides at the beginning of the data segment
* and is terminated with a -1. This one can be relocated in place.
* The second is the extra relocation entries tacked after the image's
* data segment. These require a little more processing as the entry is
* really an offset into the image which contains an offset into the
* image.
*/
if (flags & FLAT_FLAG_GOTPIC) {
rp = datapos;
while (1) {
abi_ulong addr;
if (get_user_ual(addr, rp))
return -EFAULT;
if (addr == -1)
break;
if (addr) {
addr = calc_reloc(addr, libinfo, id, 0);
if (addr == RELOC_FAILED)
return -ENOEXEC;
if (put_user_ual(addr, rp))
return -EFAULT;
}
rp += sizeof(abi_ulong);
}
}
/*
* Now run through the relocation entries.
* We've got to be careful here as C++ produces relocatable zero
* entries in the constructor and destructor tables which are then
* tested for being not zero (which will always occur unless we're
* based from address zero). This causes an endless loop as __start
* is at zero. The solution used is to not relocate zero addresses.
* This has the negative side effect of not allowing a global data
* reference to be statically initialised to _stext (I've moved
* __start to address 4 so that is okay).
*/
if (rev > OLD_FLAT_VERSION) {
abi_ulong persistent = 0;
for (i = 0; i < relocs; i++) {
abi_ulong addr, relval;
/* Get the address of the pointer to be
relocated (of course, the address has to be
relocated first). */
if (get_user_ual(relval, reloc + i * sizeof(abi_ulong)))
return -EFAULT;
relval = ntohl(relval);
if (flat_set_persistent(relval, &persistent))
continue;
addr = flat_get_relocate_addr(relval);
rp = calc_reloc(addr, libinfo, id, 1);
if (rp == RELOC_FAILED)
return -ENOEXEC;
/* Get the pointer's value. */
if (get_user_ual(addr, rp))
return -EFAULT;
addr = flat_get_addr_from_rp(addr, relval, flags, &persistent);
if (addr != 0) {
/*
* Do the relocation. PIC relocs in the data section are
* already in target order
*/
if ((flags & FLAT_FLAG_GOTPIC) == 0)
addr = ntohl(addr);
addr = calc_reloc(addr, libinfo, id, 0);
if (addr == RELOC_FAILED)
return -ENOEXEC;
/* Write back the relocated pointer. */
if (flat_put_addr_at_rp(rp, addr, relval))
return -EFAULT;
}
}
} else {
for (i = 0; i < relocs; i++) {
abi_ulong relval;
if (get_user_ual(relval, reloc + i * sizeof(abi_ulong)))
return -EFAULT;
old_reloc(&libinfo[0], relval);
}
}
/* zero the BSS. */
memset(g2h_untagged(datapos + data_len), 0, bss_len);
return 0;
}
/****************************************************************************/
int load_flt_binary(struct linux_binprm *bprm, struct image_info *info)
{
struct lib_info libinfo[MAX_SHARED_LIBS];
abi_ulong p;
abi_ulong stack_len;
abi_ulong start_addr;
abi_ulong sp;
int res;
int i, j;
memset(libinfo, 0, sizeof(libinfo));
/*
* We have to add the size of our arguments to our stack size
* otherwise it's too easy for users to create stack overflows
* by passing in a huge argument list. And yes, we have to be
* pedantic and include space for the argv/envp array as it may have
* a lot of entries.
*/
stack_len = 0;
for (i = 0; i < bprm->argc; ++i) {
/* the argv strings */
stack_len += strlen(bprm->argv[i]);
}
for (i = 0; i < bprm->envc; ++i) {
/* the envp strings */
stack_len += strlen(bprm->envp[i]);
}
stack_len += (bprm->argc + 1) * 4; /* the argv array */
stack_len += (bprm->envc + 1) * 4; /* the envp array */
mmap_lock();
res = load_flat_file(bprm, libinfo, 0, &stack_len);
mmap_unlock();
if (is_error(res)) {
return res;
}
/* Update data segment pointers for all libraries */
for (i=0; i<MAX_SHARED_LIBS; i++) {
if (libinfo[i].loaded) {
abi_ulong seg;
seg = libinfo[i].start_data;
for (j=0; j<MAX_SHARED_LIBS; j++) {
seg -= 4;
/* FIXME - handle put_user() failures */
if (put_user_ual(libinfo[j].loaded
? libinfo[j].start_data
: UNLOADED_LIB,
seg))
return -EFAULT;
}
}
}
p = ((libinfo[0].start_brk + stack_len + 3) & ~3) - 4;
DBG_FLT("p=%x\n", (int)p);
/* Copy argv/envp. */
p = copy_strings(p, bprm->envc, bprm->envp);
p = copy_strings(p, bprm->argc, bprm->argv);
/* Align stack. */
sp = p & ~(abi_ulong)(sizeof(abi_ulong) - 1);
/* Enforce final stack alignment of 16 bytes. This is sufficient
for all current targets, and excess alignment is harmless. */
stack_len = bprm->envc + bprm->argc + 2;
stack_len += flat_argvp_envp_on_stack() ? 2 : 0; /* argv, argp */
stack_len += 1; /* argc */
stack_len *= sizeof(abi_ulong);
sp -= (sp - stack_len) & 15;
sp = loader_build_argptr(bprm->envc, bprm->argc, sp, p,
flat_argvp_envp_on_stack());
/* Fake some return addresses to ensure the call chain will
* initialise library in order for us. We are required to call
* lib 1 first, then 2, ... and finally the main program (id 0).
*/
start_addr = libinfo[0].entry;
/* Stash our initial stack pointer into the mm structure */
info->start_code = libinfo[0].start_code;
info->end_code = libinfo[0].start_code + libinfo[0].text_len;
info->start_data = libinfo[0].start_data;
info->end_data = libinfo[0].end_data;
info->brk = libinfo[0].start_brk;
info->start_stack = sp;
info->stack_limit = libinfo[0].start_brk;
info->entry = start_addr;
info->code_offset = info->start_code;
info->data_offset = info->start_data - libinfo[0].text_len;
DBG_FLT("start_thread(entry=0x%x, start_stack=0x%x)\n",
(int)info->entry, (int)info->start_stack);
return 0;
}
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