/* Look up a symbol in the loaded objects.
- Copyright (C) 1995-2016 Free Software Foundation, Inc.
+ Copyright (C) 1995-2022 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
- <http://www.gnu.org/licenses/>. */
+ <https://www.gnu.org/licenses/>. */
#include <alloca.h>
#include <libintl.h>
#include <ldsodefs.h>
#include <dl-hash.h>
#include <dl-machine.h>
+#include <dl-protected.h>
#include <sysdep-cancel.h>
#include <libc-lock.h>
#include <tls.h>
#include <atomic.h>
+#include <elf_machine_sym_no_match.h>
#include <assert.h>
-/* Return nonzero if check_match should consider SYM to fail to match a
- symbol reference for some machine-specific reason. */
-#ifndef ELF_MACHINE_SYM_NO_MATCH
-# define ELF_MACHINE_SYM_NO_MATCH(sym) 0
-#endif
-
#define VERSTAG(tag) (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGIDX (tag))
-
struct sym_val
{
const ElfW(Sym) *s;
};
-#define make_string(string, rest...) \
- ({ \
- const char *all[] = { string, ## rest }; \
- size_t len, cnt; \
- char *result, *cp; \
- \
- len = 1; \
- for (cnt = 0; cnt < sizeof (all) / sizeof (all[0]); ++cnt) \
- len += strlen (all[cnt]); \
- \
- cp = result = alloca (len); \
- for (cnt = 0; cnt < sizeof (all) / sizeof (all[0]); ++cnt) \
- cp = __stpcpy (cp, all[cnt]); \
- \
- result; \
- })
-
/* Statistics function. */
#ifdef SHARED
# define bump_num_relocations() ++GL(dl_num_relocations)
unsigned int stt = ELFW(ST_TYPE) (sym->st_info);
assert (ELF_RTYPE_CLASS_PLT == 1);
if (__glibc_unlikely ((sym->st_value == 0 /* No value. */
+ && sym->st_shndx != SHN_ABS
&& stt != STT_TLS)
- || ELF_MACHINE_SYM_NO_MATCH (sym)
+ || elf_machine_sym_no_match (sym)
|| (type_class & (sym->st_shndx == SHN_UNDEF))))
return NULL;
table[idx].map = map;
}
+/* Mark MAP as NODELETE according to the lookup mode in FLAGS. During
+ initial relocation, NODELETE state is pending only. */
+static void
+mark_nodelete (struct link_map *map, int flags)
+{
+ if (flags & DL_LOOKUP_FOR_RELOCATE)
+ map->l_nodelete_pending = true;
+ else
+ map->l_nodelete_active = true;
+}
+
+/* Return true if MAP is marked as NODELETE according to the lookup
+ mode in FLAGS> */
+static bool
+is_nodelete (struct link_map *map, int flags)
+{
+ /* Non-pending NODELETE always counts. Pending NODELETE only counts
+ during initial relocation processing. */
+ return map->l_nodelete_active
+ || ((flags & DL_LOOKUP_FOR_RELOCATE) && map->l_nodelete_pending);
+}
+
/* Utility function for do_lookup_x. Lookup an STB_GNU_UNIQUE symbol
in the unique symbol table, creating a new entry if necessary.
Return the matching symbol in RESULT. */
static void
-do_lookup_unique (const char *undef_name, uint_fast32_t new_hash,
- const struct link_map *map, struct sym_val *result,
+do_lookup_unique (const char *undef_name, unsigned int new_hash,
+ struct link_map *map, struct sym_val *result,
int type_class, const ElfW(Sym) *sym, const char *strtab,
- const ElfW(Sym) *ref, const struct link_map *undef_map)
+ const ElfW(Sym) *ref, const struct link_map *undef_map,
+ int flags)
{
/* We have to determine whether we already found a symbol with this
name before. If not then we have to add it to the search table.
copy from the copy addressed through the
relocation. */
result->s = sym;
- result->m = (struct link_map *) map;
+ result->m = map;
}
else
{
tab->size = newsize;
size = newsize;
entries = tab->entries = newentries;
- tab->free = free;
+ tab->free = __rtld_free;
}
}
else
assert (!RTLD_CHECK_FOREIGN_CALL);
#endif
-#ifdef SHARED
- /* If tab->entries is NULL, but tab->size is not, it means
- this is the second, conflict finding, lookup for
- LD_TRACE_PRELINKING in _dl_debug_bindings. Don't
- allocate anything and don't enter anything into the
- hash table. */
- if (__glibc_unlikely (tab->size))
- {
- assert (GLRO(dl_debug_mask) & DL_DEBUG_PRELINK);
- goto success;
- }
-#endif
-
#define INITIAL_NUNIQUE_SYM_TABLE 31
size = INITIAL_NUNIQUE_SYM_TABLE;
entries = calloc (sizeof (struct unique_sym), size);
tab->entries = entries;
tab->size = size;
- tab->free = free;
+ tab->free = __rtld_free;
}
if ((type_class & ELF_RTYPE_CLASS_COPY) != 0)
enter_unique_sym (entries, size,
new_hash, strtab + sym->st_name, sym, map);
- if (map->l_type == lt_loaded)
- /* Make sure we don't unload this object by
- setting the appropriate flag. */
- ((struct link_map *) map)->l_flags_1 |= DF_1_NODELETE;
+ if (map->l_type == lt_loaded && !is_nodelete (map, flags))
+ {
+ /* Make sure we don't unload this object by
+ setting the appropriate flag. */
+ if (__glibc_unlikely (GLRO (dl_debug_mask) & DL_DEBUG_BINDINGS))
+ _dl_debug_printf ("\
+marking %s [%lu] as NODELETE due to unique symbol\n",
+ map->l_name, map->l_ns);
+ mark_nodelete (map, flags);
+ }
}
++tab->n_elements;
-#ifdef SHARED
- success:
-#endif
__rtld_lock_unlock_recursive (tab->lock);
result->s = sym;
something bad happened. */
static int
__attribute_noinline__
-do_lookup_x (const char *undef_name, uint_fast32_t new_hash,
+do_lookup_x (const char *undef_name, unsigned int new_hash,
unsigned long int *old_hash, const ElfW(Sym) *ref,
struct sym_val *result, struct r_scope_elem *scope, size_t i,
const struct r_found_version *const version, int flags,
do
if (((*hasharr ^ new_hash) >> 1) == 0)
{
- symidx = hasharr - map->l_gnu_chain_zero;
+ symidx = ELF_MACHINE_HASH_SYMIDX (map, hasharr);
sym = check_match (undef_name, ref, version, flags,
type_class, &symtab[symidx], symidx,
strtab, map, &versioned_sym,
#endif
}
+ /* Hidden and internal symbols are local, ignore them. */
+ if (__glibc_unlikely (dl_symbol_visibility_binds_local_p (sym)))
+ goto skip;
+
+ if (ELFW(ST_VISIBILITY) (sym->st_other) == STV_PROTECTED)
+ _dl_check_protected_symbol (undef_name, undef_map, ref, map,
+ type_class);
+
switch (ELFW(ST_BIND) (sym->st_info))
{
case STB_WEAK:
return 1;
case STB_GNU_UNIQUE:;
- do_lookup_unique (undef_name, new_hash, map, result, type_class,
- sym, strtab, ref, undef_map);
+ do_lookup_unique (undef_name, new_hash, (struct link_map *) map,
+ result, type_class, sym, strtab, ref,
+ undef_map, flags);
return 1;
default:
}
skip:
- /* If this current map is the one mentioned in the verneed entry
- and we have not found a weak entry, it is a bug. */
- if (symidx == STN_UNDEF && version != NULL && version->filename != NULL
- && __glibc_unlikely (_dl_name_match_p (version->filename, map)))
- return -1;
+ ;
}
while (++i < n);
}
-static uint_fast32_t
+static uint32_t
dl_new_hash (const char *s)
{
- uint_fast32_t h = 5381;
+ uint32_t h = 5381;
for (unsigned char c = *s; c != '\0'; c = *++s)
h = h * 33 + c;
- return h & 0xffffffff;
+ return h;
}
/* Add extra dependency on MAP to UNDEF_MAP. */
static int
-internal_function
add_dependency (struct link_map *undef_map, struct link_map *map, int flags)
{
struct link_map *runp;
if (undef_map == map)
return 0;
- /* Avoid references to objects which cannot be unloaded anyway. */
+ /* Avoid references to objects which cannot be unloaded anyway. We
+ do not need to record dependencies if this object goes away
+ during dlopen failure, either. IFUNC resolvers with relocation
+ dependencies may pick an dependency which can be dlclose'd, but
+ such IFUNC resolvers are undefined anyway. */
assert (map->l_type == lt_loaded);
- if ((map->l_flags_1 & DF_1_NODELETE) != 0)
+ if (is_nodelete (map, flags))
return 0;
struct link_map_reldeps *l_reldeps
/* Redo the NODELETE check, as when dl_load_lock wasn't held
yet this could have changed. */
- if ((map->l_flags_1 & DF_1_NODELETE) != 0)
+ if (is_nodelete (map, flags))
goto out;
/* If the object with the undefined reference cannot be removed ever
just make sure the same is true for the object which contains the
definition. */
- if (undef_map->l_type != lt_loaded
- || (undef_map->l_flags_1 & DF_1_NODELETE) != 0)
+ if (undef_map->l_type != lt_loaded || is_nodelete (map, flags))
{
- map->l_flags_1 |= DF_1_NODELETE;
+ if (__glibc_unlikely (GLRO (dl_debug_mask) & DL_DEBUG_BINDINGS)
+ && !is_nodelete (map, flags))
+ {
+ if (undef_map->l_name[0] == '\0')
+ _dl_debug_printf ("\
+marking %s [%lu] as NODELETE due to reference to main program\n",
+ map->l_name, map->l_ns);
+ else
+ _dl_debug_printf ("\
+marking %s [%lu] as NODELETE due to reference to %s [%lu]\n",
+ map->l_name, map->l_ns,
+ undef_map->l_name, undef_map->l_ns);
+ }
+ mark_nodelete (map, flags);
goto out;
}
no fatal problem. We simply make sure the referenced object
cannot be unloaded. This is semantically the correct
behavior. */
- map->l_flags_1 |= DF_1_NODELETE;
+ if (__glibc_unlikely (GLRO (dl_debug_mask) & DL_DEBUG_BINDINGS)
+ && !is_nodelete (map, flags))
+ _dl_debug_printf ("\
+marking %s [%lu] as NODELETE due to memory allocation failure\n",
+ map->l_name, map->l_ns);
+ /* In case of non-lazy binding, we could actually report
+ the memory allocation error, but for now, we use the
+ conservative approximation as well. */
+ mark_nodelete (map, flags);
goto out;
}
else
goto out;
}
-static void
-internal_function
-_dl_debug_bindings (const char *undef_name, struct link_map *undef_map,
- const ElfW(Sym) **ref, struct sym_val *value,
- const struct r_found_version *version, int type_class,
- int protected);
-
/* Search loaded objects' symbol tables for a definition of the symbol
UNDEF_NAME, perhaps with a requested version for the symbol.
or in any function which gets called. If this would happen the audit
code might create a thread which can throw off all the scope locking. */
lookup_t
-internal_function
_dl_lookup_symbol_x (const char *undef_name, struct link_map *undef_map,
const ElfW(Sym) **ref,
struct r_scope_elem *symbol_scope[],
const struct r_found_version *version,
int type_class, int flags, struct link_map *skip_map)
{
- const uint_fast32_t new_hash = dl_new_hash (undef_name);
+ const unsigned int new_hash = dl_new_hash (undef_name);
unsigned long int old_hash = 0xffffffff;
struct sym_val current_value = { NULL, NULL };
struct r_scope_elem **scope = symbol_scope;
bump_num_relocations ();
- /* No other flag than DL_LOOKUP_ADD_DEPENDENCY or DL_LOOKUP_GSCOPE_LOCK
- is allowed if we look up a versioned symbol. */
- assert (version == NULL
- || (flags & ~(DL_LOOKUP_ADD_DEPENDENCY | DL_LOOKUP_GSCOPE_LOCK))
- == 0);
+ /* DL_LOOKUP_RETURN_NEWEST does not make sense for versioned
+ lookups. */
+ assert (version == NULL || !(flags & DL_LOOKUP_RETURN_NEWEST));
size_t i = 0;
if (__glibc_unlikely (skip_map != NULL))
/* Search the relevant loaded objects for a definition. */
for (size_t start = i; *scope != NULL; start = 0, ++scope)
- {
- int res = do_lookup_x (undef_name, new_hash, &old_hash, *ref,
- ¤t_value, *scope, start, version, flags,
- skip_map, type_class, undef_map);
- if (res > 0)
- break;
-
- if (__glibc_unlikely (res < 0) && skip_map == NULL)
- {
- /* Oh, oh. The file named in the relocation entry does not
- contain the needed symbol. This code is never reached
- for unversioned lookups. */
- assert (version != NULL);
- const char *reference_name = undef_map ? undef_map->l_name : "";
-
- /* XXX We cannot translate the message. */
- _dl_signal_cerror (0, DSO_FILENAME (reference_name),
- N_("relocation error"),
- make_string ("symbol ", undef_name, ", version ",
- version->name,
- " not defined in file ",
- version->filename,
- " with link time reference",
- res == -2
- ? " (no version symbols)" : ""));
- *ref = NULL;
- return 0;
- }
- }
+ if (do_lookup_x (undef_name, new_hash, &old_hash, *ref,
+ ¤t_value, *scope, start, version, flags,
+ skip_map, type_class, undef_map) != 0)
+ break;
if (__glibc_unlikely (current_value.s == NULL))
{
if ((*ref == NULL || ELFW(ST_BIND) ((*ref)->st_info) != STB_WEAK)
- && skip_map == NULL
&& !(GLRO(dl_debug_mask) & DL_DEBUG_UNUSED))
{
/* We could find no value for a strong reference. */
const char *versionstr = version ? ", version " : "";
const char *versionname = (version && version->name
? version->name : "");
-
+ struct dl_exception exception;
/* XXX We cannot translate the message. */
- _dl_signal_cerror (0, DSO_FILENAME (reference_name),
- N_("symbol lookup error"),
- make_string ("undefined symbol: ", undef_name,
- versionstr, versionname));
+ _dl_exception_create_format
+ (&exception, DSO_FILENAME (reference_name),
+ "undefined symbol: %s%s%s",
+ undef_name, versionstr, versionname);
+ _dl_signal_cexception (0, &exception, N_("symbol lookup error"));
+ _dl_exception_free (&exception);
}
*ref = NULL;
return 0;
if (__glibc_unlikely (current_value.m->l_used == 0))
current_value.m->l_used = 1;
- if (__glibc_unlikely (GLRO(dl_debug_mask)
- & (DL_DEBUG_BINDINGS|DL_DEBUG_PRELINK)))
- _dl_debug_bindings (undef_name, undef_map, ref,
- ¤t_value, version, type_class, protected);
-
*ref = current_value.s;
return LOOKUP_VALUE (current_value.m);
}
-
-
-/* Cache the location of MAP's hash table. */
-
-void
-internal_function
-_dl_setup_hash (struct link_map *map)
-{
- Elf_Symndx *hash;
-
- if (__glibc_likely (map->l_info[DT_ADDRTAGIDX (DT_GNU_HASH) + DT_NUM
- + DT_THISPROCNUM + DT_VERSIONTAGNUM
- + DT_EXTRANUM + DT_VALNUM] != NULL))
- {
- Elf32_Word *hash32
- = (void *) D_PTR (map, l_info[DT_ADDRTAGIDX (DT_GNU_HASH) + DT_NUM
- + DT_THISPROCNUM + DT_VERSIONTAGNUM
- + DT_EXTRANUM + DT_VALNUM]);
- map->l_nbuckets = *hash32++;
- Elf32_Word symbias = *hash32++;
- Elf32_Word bitmask_nwords = *hash32++;
- /* Must be a power of two. */
- assert ((bitmask_nwords & (bitmask_nwords - 1)) == 0);
- map->l_gnu_bitmask_idxbits = bitmask_nwords - 1;
- map->l_gnu_shift = *hash32++;
-
- map->l_gnu_bitmask = (ElfW(Addr) *) hash32;
- hash32 += __ELF_NATIVE_CLASS / 32 * bitmask_nwords;
-
- map->l_gnu_buckets = hash32;
- hash32 += map->l_nbuckets;
- map->l_gnu_chain_zero = hash32 - symbias;
- return;
- }
-
- if (!map->l_info[DT_HASH])
- return;
- hash = (void *) D_PTR (map, l_info[DT_HASH]);
-
- map->l_nbuckets = *hash++;
- /* Skip nchain. */
- hash++;
- map->l_buckets = hash;
- hash += map->l_nbuckets;
- map->l_chain = hash;
-}
-
-
-static void
-internal_function
-_dl_debug_bindings (const char *undef_name, struct link_map *undef_map,
- const ElfW(Sym) **ref, struct sym_val *value,
- const struct r_found_version *version, int type_class,
- int protected)
-{
- const char *reference_name = undef_map->l_name;
-
- if (GLRO(dl_debug_mask) & DL_DEBUG_BINDINGS)
- {
- _dl_debug_printf ("binding file %s [%lu] to %s [%lu]: %s symbol `%s'",
- DSO_FILENAME (reference_name),
- undef_map->l_ns,
- DSO_FILENAME (value->m->l_name),
- value->m->l_ns,
- protected ? "protected" : "normal", undef_name);
- if (version)
- _dl_debug_printf_c (" [%s]\n", version->name);
- else
- _dl_debug_printf_c ("\n");
- }
-#ifdef SHARED
- if (GLRO(dl_debug_mask) & DL_DEBUG_PRELINK)
- {
-/* ELF_RTYPE_CLASS_XXX must match RTYPE_CLASS_XXX used by prelink with
- LD_TRACE_PRELINKING. */
-#define RTYPE_CLASS_VALID 8
-#define RTYPE_CLASS_PLT (8|1)
-#define RTYPE_CLASS_COPY (8|2)
-#define RTYPE_CLASS_TLS (8|4)
-#if ELF_RTYPE_CLASS_PLT != 0 && ELF_RTYPE_CLASS_PLT != 1
-# error ELF_RTYPE_CLASS_PLT must be 0 or 1!
-#endif
-#if ELF_RTYPE_CLASS_COPY != 0 && ELF_RTYPE_CLASS_COPY != 2
-# error ELF_RTYPE_CLASS_COPY must be 0 or 2!
-#endif
- int conflict = 0;
- struct sym_val val = { NULL, NULL };
-
- if ((GLRO(dl_trace_prelink_map) == NULL
- || GLRO(dl_trace_prelink_map) == GL(dl_ns)[LM_ID_BASE]._ns_loaded)
- && undef_map != GL(dl_ns)[LM_ID_BASE]._ns_loaded)
- {
- const uint_fast32_t new_hash = dl_new_hash (undef_name);
- unsigned long int old_hash = 0xffffffff;
- struct unique_sym *saved_entries
- = GL(dl_ns)[LM_ID_BASE]._ns_unique_sym_table.entries;
-
- GL(dl_ns)[LM_ID_BASE]._ns_unique_sym_table.entries = NULL;
- do_lookup_x (undef_name, new_hash, &old_hash, *ref, &val,
- undef_map->l_local_scope[0], 0, version, 0, NULL,
- type_class, undef_map);
- if (val.s != value->s || val.m != value->m)
- conflict = 1;
- else if (__glibc_unlikely (undef_map->l_symbolic_in_local_scope)
- && val.s
- && __glibc_unlikely (ELFW(ST_BIND) (val.s->st_info)
- == STB_GNU_UNIQUE))
- {
- /* If it is STB_GNU_UNIQUE and undef_map's l_local_scope
- contains any DT_SYMBOLIC libraries, unfortunately there
- can be conflicts even if the above is equal. As symbol
- resolution goes from the last library to the first and
- if a STB_GNU_UNIQUE symbol is found in some late DT_SYMBOLIC
- library, it would be the one that is looked up. */
- struct sym_val val2 = { NULL, NULL };
- size_t n;
- struct r_scope_elem *scope = undef_map->l_local_scope[0];
-
- for (n = 0; n < scope->r_nlist; n++)
- if (scope->r_list[n] == val.m)
- break;
-
- for (n++; n < scope->r_nlist; n++)
- if (scope->r_list[n]->l_info[DT_SYMBOLIC] != NULL
- && do_lookup_x (undef_name, new_hash, &old_hash, *ref,
- &val2,
- &scope->r_list[n]->l_symbolic_searchlist,
- 0, version, 0, NULL, type_class,
- undef_map) > 0)
- {
- conflict = 1;
- val = val2;
- break;
- }
- }
- GL(dl_ns)[LM_ID_BASE]._ns_unique_sym_table.entries = saved_entries;
- }
-
- if (value->s)
- {
- /* Keep only ELF_RTYPE_CLASS_PLT and ELF_RTYPE_CLASS_COPY
- bits since since prelink only uses them. */
- type_class &= ELF_RTYPE_CLASS_PLT | ELF_RTYPE_CLASS_COPY;
- if (__glibc_unlikely (ELFW(ST_TYPE) (value->s->st_info)
- == STT_TLS))
- /* Clear the RTYPE_CLASS_VALID bit in RTYPE_CLASS_TLS. */
- type_class = RTYPE_CLASS_TLS & ~RTYPE_CLASS_VALID;
- else if (__glibc_unlikely (ELFW(ST_TYPE) (value->s->st_info)
- == STT_GNU_IFUNC))
- /* Set the RTYPE_CLASS_VALID bit. */
- type_class |= RTYPE_CLASS_VALID;
- }
-
- if (conflict
- || GLRO(dl_trace_prelink_map) == undef_map
- || GLRO(dl_trace_prelink_map) == NULL
- || type_class >= 4)
- {
- _dl_printf ("%s 0x%0*Zx 0x%0*Zx -> 0x%0*Zx 0x%0*Zx ",
- conflict ? "conflict" : "lookup",
- (int) sizeof (ElfW(Addr)) * 2,
- (size_t) undef_map->l_map_start,
- (int) sizeof (ElfW(Addr)) * 2,
- (size_t) (((ElfW(Addr)) *ref) - undef_map->l_map_start),
- (int) sizeof (ElfW(Addr)) * 2,
- (size_t) (value->s ? value->m->l_map_start : 0),
- (int) sizeof (ElfW(Addr)) * 2,
- (size_t) (value->s ? value->s->st_value : 0));
-
- if (conflict)
- _dl_printf ("x 0x%0*Zx 0x%0*Zx ",
- (int) sizeof (ElfW(Addr)) * 2,
- (size_t) (val.s ? val.m->l_map_start : 0),
- (int) sizeof (ElfW(Addr)) * 2,
- (size_t) (val.s ? val.s->st_value : 0));
-
- _dl_printf ("/%x %s\n", type_class, undef_name);
- }
- }
-#endif
-}
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