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kernel linker: do not read debug symbol tables for non-debug symbols

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In particular, this prevents resolving locals from other files.
To access debug symbol tables, add LINKER_LOOKUP_DEBUG_SYMBOL and
LINKER_DEBUG_SYMBOL_VALUES kobj methods, which are allowed to use
any types of present symbols in all tables.

PR:	207898
Reviewed by:	emaste, markj
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D32878
This commit is contained in:
Konstantin Belousov 2021-11-07 10:37:48 +02:00
parent 72f6662662
commit 95c20faf11
4 changed files with 126 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
sys/kern/kern_linker.c
View File

@ -912,7 +912,7 @@ linker_debug_lookup(const char *symstr, c_linker_sym_t *sym)
linker_file_t lf;
TAILQ_FOREACH(lf, &linker_files, link) {
if (LINKER_LOOKUP_SYMBOL(lf, symstr, sym) == 0)
if (LINKER_LOOKUP_DEBUG_SYMBOL(lf, symstr, sym) == 0)
return (0);
}
return (ENOENT);

79
sys/kern/link_elf.c
View File

@ -144,8 +144,12 @@ static int link_elf_load_file(linker_class_t, const char *,
linker_file_t *);
static int link_elf_lookup_symbol(linker_file_t, const char *,
c_linker_sym_t *);
static int link_elf_lookup_debug_symbol(linker_file_t, const char *,
c_linker_sym_t *);
static int link_elf_symbol_values(linker_file_t, c_linker_sym_t,
linker_symval_t *);
static int link_elf_debug_symbol_values(linker_file_t, c_linker_sym_t,
linker_symval_t*);
static int link_elf_search_symbol(linker_file_t, caddr_t,
c_linker_sym_t *, long *);
@ -164,7 +168,9 @@ static int elf_lookup(linker_file_t, Elf_Size, int, Elf_Addr *);
static kobj_method_t link_elf_methods[] = {
KOBJMETHOD(linker_lookup_symbol, link_elf_lookup_symbol),
KOBJMETHOD(linker_lookup_debug_symbol, link_elf_lookup_debug_symbol),
KOBJMETHOD(linker_symbol_values, link_elf_symbol_values),
KOBJMETHOD(linker_debug_symbol_values, link_elf_debug_symbol_values),
KOBJMETHOD(linker_search_symbol, link_elf_search_symbol),
KOBJMETHOD(linker_unload, link_elf_unload_file),
KOBJMETHOD(linker_load_file, link_elf_load_file),
@ -1490,14 +1496,14 @@ elf_hash(const char *name)
}
static int
link_elf_lookup_symbol(linker_file_t lf, const char *name, c_linker_sym_t *sym)
link_elf_lookup_symbol1(linker_file_t lf, const char *name, c_linker_sym_t *sym,
bool see_local)
{
elf_file_t ef = (elf_file_t) lf;
unsigned long symnum;
const Elf_Sym* symp;
const char *strp;
unsigned long hash;
int i;
/* If we don't have a hash, bail. */
if (ef->buckets == NULL || ef->nbuckets == 0) {
@ -1528,8 +1534,11 @@ link_elf_lookup_symbol(linker_file_t lf, const char *name, c_linker_sym_t *sym)
(symp->st_value != 0 &&
(ELF_ST_TYPE(symp->st_info) == STT_FUNC ||
ELF_ST_TYPE(symp->st_info) == STT_GNU_IFUNC))) {
*sym = (c_linker_sym_t) symp;
return (0);
if (see_local ||
ELF_ST_BIND(symp->st_info) != STB_LOCAL) {
*sym = (c_linker_sym_t) symp;
return (0);
}
}
return (ENOENT);
}
@ -1537,11 +1546,27 @@ link_elf_lookup_symbol(linker_file_t lf, const char *name, c_linker_sym_t *sym)
symnum = ef->chains[symnum];
}
/* If we have not found it, look at the full table (if loaded) */
if (ef->symtab == ef->ddbsymtab)
return (ENOENT);
return (ENOENT);
}
static int
link_elf_lookup_symbol(linker_file_t lf, const char *name, c_linker_sym_t *sym)
{
return (link_elf_lookup_symbol1(lf, name, sym, false));
}
static int
link_elf_lookup_debug_symbol(linker_file_t lf, const char *name,
c_linker_sym_t *sym)
{
elf_file_t ef = (elf_file_t)lf;
const Elf_Sym* symp;
const char *strp;
int i;
if (link_elf_lookup_symbol1(lf, name, sym, true) == 0)
return (0);
/* Exhaustive search */
for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
strp = ef->ddbstrtab + symp->st_name;
if (strcmp(name, strp) == 0) {
@ -1560,8 +1585,8 @@ link_elf_lookup_symbol(linker_file_t lf, const char *name, c_linker_sym_t *sym)
}
static int
link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym,
linker_symval_t *symval)
link_elf_symbol_values1(linker_file_t lf, c_linker_sym_t sym,
linker_symval_t *symval, bool see_local)
{
elf_file_t ef;
const Elf_Sym *es;
@ -1569,7 +1594,9 @@ link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym,
ef = (elf_file_t)lf;
es = (const Elf_Sym *)sym;
if (es >= ef->symtab && es < (ef->symtab + ef->nchains)) {
if (es >= ef->symtab && es < ef->symtab + ef->nchains) {
if (!see_local && ELF_ST_BIND(es->st_info) == STB_LOCAL)
return (ENOENT);
symval->name = ef->strtab + es->st_name;
val = (caddr_t)ef->address + es->st_value;
if (ELF_ST_TYPE(es->st_info) == STT_GNU_IFUNC)
@ -1578,8 +1605,29 @@ link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym,
symval->size = es->st_size;
return (0);
}
return (ENOENT);
}
static int
link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym,
linker_symval_t *symval)
{
return (link_elf_symbol_values1(lf, sym, symval, false));
}
static int
link_elf_debug_symbol_values(linker_file_t lf, c_linker_sym_t sym,
linker_symval_t *symval)
{
elf_file_t ef = (elf_file_t)lf;
const Elf_Sym *es = (const Elf_Sym *)sym;
caddr_t val;
if (link_elf_symbol_values1(lf, sym, symval, true) == 0)
return (0);
if (ef->symtab == ef->ddbsymtab)
return (ENOENT);
if (es >= ef->ddbsymtab && es < (ef->ddbsymtab + ef->ddbsymcnt)) {
symval->name = ef->ddbstrtab + es->st_name;
val = (caddr_t)ef->address + es->st_value;
@ -1597,7 +1645,7 @@ link_elf_search_symbol(linker_file_t lf, caddr_t value,
c_linker_sym_t *sym, long *diffp)
{
elf_file_t ef = (elf_file_t)lf;
u_long off = (uintptr_t) (void *)value;
u_long off = (uintptr_t)(void *)value;
u_long diff = off;
u_long st_value;
const Elf_Sym *es;
@ -1719,11 +1767,10 @@ link_elf_each_function_nameval(linker_file_t file,
if (symp->st_value != 0 &&
(ELF_ST_TYPE(symp->st_info) == STT_FUNC ||
ELF_ST_TYPE(symp->st_info) == STT_GNU_IFUNC)) {
error = link_elf_symbol_values(file,
error = link_elf_debug_symbol_values(file,
(c_linker_sym_t) symp, &symval);
if (error != 0)
return (error);
error = callback(file, i, &symval, opaque);
if (error == 0)
error = callback(file, i, &symval, opaque);
if (error != 0)
return (error);
}

61
sys/kern/link_elf_obj.c
View File

@ -131,8 +131,12 @@ static int link_elf_link_preload_finish(linker_file_t);
static int link_elf_load_file(linker_class_t, const char *, linker_file_t *);
static int link_elf_lookup_symbol(linker_file_t, const char *,
c_linker_sym_t *);
static int link_elf_lookup_debug_symbol(linker_file_t, const char *,
c_linker_sym_t *);
static int link_elf_symbol_values(linker_file_t, c_linker_sym_t,
linker_symval_t *);
static int link_elf_debug_symbol_values(linker_file_t, c_linker_sym_t,
linker_symval_t *);
static int link_elf_search_symbol(linker_file_t, caddr_t value,
c_linker_sym_t *sym, long *diffp);
@ -153,7 +157,9 @@ static int elf_obj_lookup(linker_file_t lf, Elf_Size symidx, int deps,
static kobj_method_t link_elf_methods[] = {
KOBJMETHOD(linker_lookup_symbol, link_elf_lookup_symbol),
KOBJMETHOD(linker_lookup_debug_symbol, link_elf_lookup_debug_symbol),
KOBJMETHOD(linker_symbol_values, link_elf_symbol_values),
KOBJMETHOD(linker_debug_symbol_values, link_elf_debug_symbol_values),
KOBJMETHOD(linker_search_symbol, link_elf_search_symbol),
KOBJMETHOD(linker_unload, link_elf_unload_file),
KOBJMETHOD(linker_load_file, link_elf_load_file),
@ -1424,9 +1430,10 @@ relocate_file(elf_file_t ef)
}
static int
link_elf_lookup_symbol(linker_file_t lf, const char *name, c_linker_sym_t *sym)
link_elf_lookup_symbol1(linker_file_t lf, const char *name, c_linker_sym_t *sym,
bool see_local)
{
elf_file_t ef = (elf_file_t) lf;
elf_file_t ef = (elf_file_t)lf;
const Elf_Sym *symp;
const char *strp;
int i;
@ -1434,16 +1441,33 @@ link_elf_lookup_symbol(linker_file_t lf, const char *name, c_linker_sym_t *sym)
for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) {
strp = ef->ddbstrtab + symp->st_name;
if (symp->st_shndx != SHN_UNDEF && strcmp(name, strp) == 0) {
*sym = (c_linker_sym_t) symp;
return 0;
if (see_local ||
ELF_ST_BIND(symp->st_info) == STB_GLOBAL) {
*sym = (c_linker_sym_t) symp;
return (0);
}
return (ENOENT);
}
}
return (ENOENT);
}
static int
link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym,
linker_symval_t *symval)
link_elf_lookup_symbol(linker_file_t lf, const char *name, c_linker_sym_t *sym)
{
return (link_elf_lookup_symbol1(lf, name, sym, false));
}
static int
link_elf_lookup_debug_symbol(linker_file_t lf, const char *name,
c_linker_sym_t *sym)
{
return (link_elf_lookup_symbol1(lf, name, sym, true));
}
static int
link_elf_symbol_values1(linker_file_t lf, c_linker_sym_t sym,
linker_symval_t *symval, bool see_local)
{
elf_file_t ef;
const Elf_Sym *es;
@ -1453,6 +1477,8 @@ link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym,
es = (const Elf_Sym*) sym;
val = (caddr_t)es->st_value;
if (es >= ef->ddbsymtab && es < (ef->ddbsymtab + ef->ddbsymcnt)) {
if (!see_local && ELF_ST_BIND(es->st_info) == STB_LOCAL)
return (ENOENT);
symval->name = ef->ddbstrtab + es->st_name;
val = (caddr_t)es->st_value;
if (ELF_ST_TYPE(es->st_info) == STT_GNU_IFUNC)
@ -1464,6 +1490,20 @@ link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym,
return (ENOENT);
}
static int
link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym,
linker_symval_t *symval)
{
return (link_elf_symbol_values1(lf, sym, symval, false));
}
static int
link_elf_debug_symbol_values(linker_file_t lf, c_linker_sym_t sym,
linker_symval_t *symval)
{
return (link_elf_symbol_values1(lf, sym, symval, true));
}
static int
link_elf_search_symbol(linker_file_t lf, caddr_t value,
c_linker_sym_t *sym, long *diffp)
@ -1566,12 +1606,11 @@ link_elf_each_function_nameval(linker_file_t file,
if (symp->st_value != 0 &&
(ELF_ST_TYPE(symp->st_info) == STT_FUNC ||
ELF_ST_TYPE(symp->st_info) == STT_GNU_IFUNC)) {
error = link_elf_symbol_values(file,
error = link_elf_debug_symbol_values(file,
(c_linker_sym_t)symp, &symval);
if (error)
return (error);
error = callback(file, i, &symval, opaque);
if (error)
if (error == 0)
error = callback(file, i, &symval, opaque);
if (error != 0)
return (error);
}
}

12
sys/kern/linker_if.m
View File

@ -40,12 +40,24 @@ METHOD int lookup_symbol {
c_linker_sym_t* symp;
};
METHOD int lookup_debug_symbol {
linker_file_t file;
const char* name;
c_linker_sym_t* symp;
};
METHOD int symbol_values {
linker_file_t file;
c_linker_sym_t sym;
linker_symval_t* valp;
};
METHOD int debug_symbol_values {
linker_file_t file;
c_linker_sym_t sym;
linker_symval_t* valp;
};
METHOD int search_symbol {
linker_file_t file;
caddr_t value;