git: 95c20faf11a1 - main - kernel linker: do not read debug symbol tables for non-debug symbols
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Date: Wed, 08 Dec 2021 21:59:28 UTC
The branch main has been updated by kib:
URL: https://cgit.FreeBSD.org/src/commit/?id=95c20faf11a1af6924f97ec4aafc32d899fea8b0
commit 95c20faf11a1af6924f97ec4aafc32d899fea8b0
Author: Konstantin Belousov <kib@FreeBSD.org>
AuthorDate: 2021-11-07 08:37:48 +0000
Commit: Konstantin Belousov <kib@FreeBSD.org>
CommitDate: 2021-12-08 21:32:29 +0000
kernel linker: do not read debug symbol tables for non-debug symbols
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
---
sys/kern/kern_linker.c | 2 +-
sys/kern/link_elf.c | 79 +++++++++++++++++++++++++++++++++++++++----------
sys/kern/link_elf_obj.c | 61 +++++++++++++++++++++++++++++++-------
sys/kern/linker_if.m | 12 ++++++++
4 files changed, 126 insertions(+), 28 deletions(-)
diff --git a/sys/kern/kern_linker.c b/sys/kern/kern_linker.c
index b34131604fef..2e4c95f16c8f 100644
--- a/sys/kern/kern_linker.c
+++ b/sys/kern/kern_linker.c
@@ -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);
diff --git a/sys/kern/link_elf.c b/sys/kern/link_elf.c
index 075238b91d95..dc8002be0e89 100644
--- a/sys/kern/link_elf.c
+++ b/sys/kern/link_elf.c
@@ -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);
}
diff --git a/sys/kern/link_elf_obj.c b/sys/kern/link_elf_obj.c
index fbefd0f8d7ca..ec2319ffad47 100644
--- a/sys/kern/link_elf_obj.c
+++ b/sys/kern/link_elf_obj.c
@@ -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);
}
}
diff --git a/sys/kern/linker_if.m b/sys/kern/linker_if.m
index a583a0369ebc..524f786ccac8 100644
--- a/sys/kern/linker_if.m
+++ b/sys/kern/linker_if.m
@@ -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;