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Perform additional checks when translating between file and memory

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representations of ELF types.

The ELF(3) API allows applications to request a conversion that is
`in-place', i.e., with source and destinations data buffers being
the same.  However, the file and memory sizes of ELF sections that
have additional internal structure, such as those of type `Elf_Note',
or `Elf_GNU_Hash_Header', can be determined only known after the
type-specific headers that comprise the first few words in these
sections are read and translated.

Pass in the size of destination buffer to type translation routines
in "libelf_convert.m4" and have these routines return an error code
if the translated data would not fit inside the destination buffer.

Obtained from:	elftoolchain
MFC after:		1 month
This commit is contained in:
Kai Wang 2010-07-21 10:25:02 +00:00
parent 4e55157fa4
commit f0f10541db
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=210338
7 changed files with 114 additions and 65 deletions
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4
lib/libelf/_libelf.h
View File

@ -171,8 +171,8 @@ void *_libelf_ehdr(Elf *_e, int _elfclass, int _allocate);
int _libelf_falign(Elf_Type _t, int _elfclass);
size_t _libelf_fsize(Elf_Type _t, int _elfclass, unsigned int _version,
size_t count);
void (*_libelf_get_translator(Elf_Type _t, int _direction, int _elfclass))
(char *_dst, char *_src, size_t _cnt, int _byteswap);
int (*_libelf_get_translator(Elf_Type _t, int _direction, int _elfclass))
(char *_dst, size_t dsz, char *_src, size_t _cnt, int _byteswap);
void *_libelf_getphdr(Elf *_e, int _elfclass);
void *_libelf_getshdr(Elf_Scn *_scn, int _elfclass);
void _libelf_init_elf(Elf *_e, Elf_Kind _kind);

13
lib/libelf/elf_data.c
View File

@ -43,7 +43,7 @@ elf_getdata(Elf_Scn *s, Elf_Data *d)
int elfclass, elftype;
unsigned int sh_type;
uint64_t sh_align, sh_offset, sh_size;
void (*xlate)(char *_d, char *_s, size_t _c, int _swap);
int (*xlate)(char *_d, size_t _dsz, char *_s, size_t _c, int _swap);
if (s == NULL || (e = s->s_elf) == NULL || e->e_kind != ELF_K_ELF ||
(d != NULL && s != d->d_scn)) {
@ -125,11 +125,16 @@ elf_getdata(Elf_Scn *s, Elf_Data *d)
}
d->d_flags |= LIBELF_F_MALLOCED;
STAILQ_INSERT_TAIL(&s->s_data, d, d_next);
xlate = _libelf_get_translator(elftype, ELF_TOMEMORY, elfclass);
(*xlate)(d->d_buf, e->e_rawfile + sh_offset, count, e->e_byteorder !=
LIBELF_PRIVATE(byteorder));
if (!(*xlate)(d->d_buf, d->d_size, e->e_rawfile + sh_offset, count,
e->e_byteorder != LIBELF_PRIVATE(byteorder))) {
_libelf_release_data(d);
LIBELF_SET_ERROR(DATA, 0);
return (NULL);
}
STAILQ_INSERT_TAIL(&s->s_data, d, d_next);
return (d);
}

5
lib/libelf/elf_scn.c
View File

@ -48,7 +48,7 @@ _libelf_load_scn(Elf *e, void *ehdr)
Elf32_Ehdr *eh32;
Elf64_Ehdr *eh64;
Elf_Scn *scn;
void (*xlator)(char *_d, char *_s, size_t _c, int _swap);
int (*xlator)(char *_d, size_t _dsz, char *_s, size_t _c, int _swap);
assert(e != NULL);
assert(ehdr != NULL);
@ -101,7 +101,8 @@ _libelf_load_scn(Elf *e, void *ehdr)
if ((scn = _libelf_allocate_scn(e, i)) == NULL)
return (0);
(*xlator)((char *) &scn->s_shdr, src, (size_t) 1, swapbytes);
(*xlator)((char *) &scn->s_shdr, sizeof(scn->s_shdr), src,
(size_t) 1, swapbytes);
if (ec == ELFCLASS32) {
scn->s_offset = scn->s_rawoff =

132
lib/libelf/libelf_convert.m4
View File

@ -236,6 +236,7 @@ IGNORE(MOVEP)
IGNORE(NOTE)
define(IGNORE_BYTE, 1) /* 'lator, leave 'em bytes alone */
define(IGNORE_GNUHASH, 1)
define(IGNORE_NOTE, 1)
define(IGNORE_SXWORD32, 1)
define(IGNORE_XWORD32, 1)
@ -274,18 +275,18 @@ define(`SIZEDEP_OFF', 1)
* `$4': ELF class specifier for types, one of [`32', `64']
*/
define(`MAKEPRIM_TO_F',`
static void
libelf_cvt_$1$3_tof(char *dst, char *src, size_t count, int byteswap)
static int
libelf_cvt_$1$3_tof(char *dst, size_t dsz, char *src, size_t count,
int byteswap)
{
Elf$4_$2 t, *s = (Elf$4_$2 *) (uintptr_t) src;
size_t c;
if (dst == src && !byteswap)
return;
(void) dsz;
if (!byteswap) {
(void) memcpy(dst, src, count * sizeof(*s));
return;
return (1);
}
for (c = 0; c < count; c++) {
@ -293,22 +294,25 @@ libelf_cvt_$1$3_tof(char *dst, char *src, size_t count, int byteswap)
SWAP_$1$3(t);
WRITE_$1$3(dst,t);
}
return (1);
}
')
define(`MAKEPRIM_TO_M',`
static void
libelf_cvt_$1$3_tom(char *dst, char *src, size_t count, int byteswap)
static int
libelf_cvt_$1$3_tom(char *dst, size_t dsz, char *src, size_t count,
int byteswap)
{
Elf$4_$2 t, *d = (Elf$4_$2 *) (uintptr_t) dst;
size_t c;
if (dst == src && !byteswap)
return;
if (dsz < count * sizeof(Elf$4_$2))
return (0);
if (!byteswap) {
(void) memcpy(dst, src, count * sizeof(*d));
return;
return (1);
}
for (c = 0; c < count; c++) {
@ -316,6 +320,8 @@ libelf_cvt_$1$3_tom(char *dst, char *src, size_t count, int byteswap)
SWAP_$1$3(t);
*d++ = t;
}
return (1);
}
')
@ -392,12 +398,15 @@ define(`READ_STRUCT',
define(`MAKE_TO_F',
`ifdef(`IGNORE_'$1$3,`',`
static void
libelf_cvt$3_$1_tof(char *dst, char *src, size_t count, int byteswap)
static int
libelf_cvt$3_$1_tof(char *dst, size_t dsz, char *src, size_t count,
int byteswap)
{
Elf$3_$2 t, *s;
size_t c;
(void) dsz;
s = (Elf$3_$2 *) (uintptr_t) src;
for (c = 0; c < count; c++) {
t = *s++;
@ -406,13 +415,16 @@ libelf_cvt$3_$1_tof(char *dst, char *src, size_t count, int byteswap)
}
WRITE_STRUCT($2,$3)
}
return (1);
}
')')
define(`MAKE_TO_M',
`ifdef(`IGNORE_'$1$3,`',`
static void
libelf_cvt$3_$1_tom(char *dst, char *src, size_t count, int byteswap)
static int
libelf_cvt$3_$1_tom(char *dst, size_t dsz, char *src, size_t count,
int byteswap)
{
Elf$3_$2 t, *d;
unsigned char *s,*s0;
@ -422,6 +434,9 @@ libelf_cvt$3_$1_tom(char *dst, char *src, size_t count, int byteswap)
d = ((Elf$3_$2 *) (uintptr_t) dst) + (count - 1);
s0 = (unsigned char *) src + (count - 1) * fsz;
if (dsz < count * sizeof(Elf$3_$2))
return (0);
while (count--) {
s = s0;
READ_STRUCT($2,$3)
@ -430,6 +445,8 @@ libelf_cvt$3_$1_tom(char *dst, char *src, size_t count, int byteswap)
}
*d-- = t; s0 -= fsz;
}
return (1);
}
')')
@ -475,12 +492,16 @@ divert(0)
* simple memcpy suffices for both directions of conversion.
*/
static void
libelf_cvt_BYTE_tox(char *dst, char *src, size_t count, int byteswap)
static int
libelf_cvt_BYTE_tox(char *dst, size_t dsz, char *src, size_t count,
int byteswap)
{
(void) byteswap;
if (dsz < count)
return (0);
if (dst != src)
(void) memcpy(dst, src, count);
return (1);
}
/*
@ -490,69 +511,81 @@ libelf_cvt_BYTE_tox(char *dst, char *src, size_t count, int byteswap)
*
* Argument `count' denotes the total number of bytes to be converted.
*/
static void
libelf_cvt_NOTE_tom(char *dst, char *src, size_t count, int byteswap)
static int
libelf_cvt_NOTE_tom(char *dst, size_t dsz, char *src, size_t count,
int byteswap)
{
uint32_t namesz, descsz, type;
Elf_Note *en;
size_t sz;
size_t sz, hdrsz;
if (dst == src && !byteswap)
return;
if (dsz < count) /* Destination buffer is too small. */
return (0);
hdrsz = 3 * sizeof(uint32_t);
if (count < hdrsz) /* Source too small. */
return (0);
if (!byteswap) {
(void) memcpy(dst, src, count);
return;
return (1);
}
while (count > sizeof(Elf_Note)) {
/* Process all notes in the section. */
while (count > hdrsz) {
/* Read the note header. */
READ_WORD(src, namesz);
READ_WORD(src, descsz);
READ_WORD(src, type);
if (byteswap) {
SWAP_WORD(namesz);
SWAP_WORD(descsz);
SWAP_WORD(type);
}
/* Translate. */
SWAP_WORD(namesz);
SWAP_WORD(descsz);
SWAP_WORD(type);
/* Copy out the translated note header. */
en = (Elf_Note *) (uintptr_t) dst;
en->n_namesz = namesz;
en->n_descsz = descsz;
en->n_type = type;
dsz -= sizeof(Elf_Note);
dst += sizeof(Elf_Note);
count -= hdrsz;
ROUNDUP2(namesz, 4);
ROUNDUP2(descsz, 4);
sz = namesz + descsz;
if (count < sz)
sz = count;
if (count < sz || dsz < sz) /* Buffers are too small. */
return (0);
(void) memcpy(dst, src, sz);
src += sz;
dst += sz;
count -= sz;
}
return (1);
}
static void
libelf_cvt_NOTE_tof(char *dst, char *src, size_t count, int byteswap)
static int
libelf_cvt_NOTE_tof(char *dst, size_t dsz, char *src, size_t count,
int byteswap)
{
uint32_t namesz, descsz, type;
Elf_Note *en;
size_t sz;
if (dst == src && !byteswap)
return;
if (dsz < count)
return (0);
if (!byteswap) {
(void) memcpy(dst, src, count);
return;
return (1);
}
while (count > sizeof(Elf_Note)) {
@ -562,12 +595,9 @@ libelf_cvt_NOTE_tof(char *dst, char *src, size_t count, int byteswap)
descsz = en->n_descsz;
type = en->n_type;
if (byteswap) {
SWAP_WORD(namesz);
SWAP_WORD(descsz);
SWAP_WORD(type);
}
SWAP_WORD(namesz);
SWAP_WORD(descsz);
SWAP_WORD(type);
WRITE_WORD(dst, namesz);
WRITE_WORD(dst, descsz);
@ -589,15 +619,21 @@ libelf_cvt_NOTE_tof(char *dst, char *src, size_t count, int byteswap)
dst += sz;
count -= sz;
}
return (1);
}
MAKE_TYPE_CONVERTERS(ELF_TYPE_LIST)
struct converters {
void (*tof32)(char *dst, char *src, size_t cnt, int byteswap);
void (*tom32)(char *dst, char *src, size_t cnt, int byteswap);
void (*tof64)(char *dst, char *src, size_t cnt, int byteswap);
void (*tom64)(char *dst, char *src, size_t cnt, int byteswap);
int (*tof32)(char *dst, size_t dsz, char *src, size_t cnt,
int byteswap);
int (*tom32)(char *dst, size_t dsz, char *src, size_t cnt,
int byteswap);
int (*tof64)(char *dst, size_t dsz, char *src, size_t cnt,
int byteswap);
int (*tom64)(char *dst, size_t dsz, char *src, size_t cnt,
int byteswap);
};
divert(-1)
@ -647,8 +683,8 @@ CONVERTER_NAMES(ELF_TYPE_LIST)
}
};
void (*_libelf_get_translator(Elf_Type t, int direction, int elfclass))
(char *_dst, char *_src, size_t _cnt, int _byteswap)
int (*_libelf_get_translator(Elf_Type t, int direction, int elfclass))
(char *_dst, size_t dsz, char *_src, size_t _cnt, int _byteswap)
{
assert(elfclass == ELFCLASS32 || elfclass == ELFCLASS64);
assert(direction == ELF_TOFILE || direction == ELF_TOMEMORY);

9
lib/libelf/libelf_ehdr.c
View File

@ -46,7 +46,7 @@ _libelf_load_extended(Elf *e, int ec, uint64_t shoff, uint16_t phnum,
{
Elf_Scn *scn;
size_t fsz;
void (*xlator)(char *_d, char *_s, size_t _c, int _swap);
int (*xlator)(char *_d, size_t _dsz, char *_s, size_t _c, int _swap);
uint32_t shtype;
assert(STAILQ_EMPTY(&e->e_u.e_elf.e_scn));
@ -63,7 +63,8 @@ _libelf_load_extended(Elf *e, int ec, uint64_t shoff, uint16_t phnum,
return (0);
xlator = _libelf_get_translator(ELF_T_SHDR, ELF_TOMEMORY, ec);
(*xlator)((char *) &scn->s_shdr, e->e_rawfile + shoff, (size_t) 1,
(*xlator)((char *) &scn->s_shdr, sizeof(scn->s_shdr),
e->e_rawfile + shoff, (size_t) 1,
e->e_byteorder != LIBELF_PRIVATE(byteorder));
#define GET_SHDR_MEMBER(M) ((ec == ELFCLASS32) ? scn->s_shdr.s_shdr32.M : \
@ -105,7 +106,7 @@ _libelf_ehdr(Elf *e, int ec, int allocate)
size_t fsz, msz;
uint16_t phnum, shnum, strndx;
uint64_t shoff;
void (*xlator)(char *_d, char *_s, size_t _c, int _swap);
int (*xlator)(char *_d, size_t _dsz, char *_s, size_t _c, int _swap);
assert(ec == ELFCLASS32 || ec == ELFCLASS64);
@ -167,7 +168,7 @@ _libelf_ehdr(Elf *e, int ec, int allocate)
return (ehdr);
xlator = _libelf_get_translator(ELF_T_EHDR, ELF_TOMEMORY, ec);
(*xlator)(ehdr, e->e_rawfile, (size_t) 1,
(*xlator)(ehdr, msz, e->e_rawfile, (size_t) 1,
e->e_byteorder != LIBELF_PRIVATE(byteorder));
/*

4
lib/libelf/libelf_phdr.c
View File

@ -45,7 +45,7 @@ _libelf_getphdr(Elf *e, int ec)
Elf32_Ehdr *eh32;
Elf64_Ehdr *eh64;
void *ehdr, *phdr;
void (*xlator)(char *_d, char *_s, size_t _c, int _swap);
int (*xlator)(char *_d, size_t _dsz, char *_s, size_t _c, int _swap);
assert(ec == ELFCLASS32 || ec == ELFCLASS64);
@ -103,7 +103,7 @@ _libelf_getphdr(Elf *e, int ec)
xlator = _libelf_get_translator(ELF_T_PHDR, ELF_TOMEMORY, ec);
(*xlator)(phdr, e->e_rawfile + phoff, phnum,
(*xlator)(phdr, phnum * msz, e->e_rawfile + phoff, phnum,
e->e_byteorder != LIBELF_PRIVATE(byteorder));
return (phdr);

12
lib/libelf/libelf_xlate.c
View File

@ -48,6 +48,7 @@ Elf_Data *
_libelf_xlate(Elf_Data *dst, const Elf_Data *src, unsigned int encoding,
int elfclass, int direction)
{
int byteswap;
size_t cnt, dsz, fsz, msz;
uintptr_t sb, se, db, de;
@ -132,12 +133,17 @@ _libelf_xlate(Elf_Data *dst, const Elf_Data *src, unsigned int encoding,
dst->d_type = src->d_type;
dst->d_size = dsz;
byteswap = encoding != LIBELF_PRIVATE(byteorder);
if (src->d_size == 0 ||
(db == sb && encoding == LIBELF_PRIVATE(byteorder) && fsz == msz))
(db == sb && !byteswap && fsz == msz))
return (dst); /* nothing more to do */
(_libelf_get_translator(src->d_type, direction, elfclass))(dst->d_buf,
src->d_buf, cnt, encoding != LIBELF_PRIVATE(byteorder));
if (!(_libelf_get_translator(src->d_type, direction, elfclass))
(dst->d_buf, dsz, src->d_buf, cnt, byteswap)) {
LIBELF_SET_ERROR(DATA, 0);
return (NULL);
}
return (dst);
}