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-rw-r--r--libexec/ld.so/resolve.c124
1 files changed, 107 insertions, 17 deletions
diff --git a/libexec/ld.so/resolve.c b/libexec/ld.so/resolve.c
index e1df6956e4b..c1f9eddfb44 100644
--- a/libexec/ld.so/resolve.c
+++ b/libexec/ld.so/resolve.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: resolve.c,v 1.86 2018/11/16 21:15:47 guenther Exp $ */
+/* $OpenBSD: resolve.c,v 1.87 2018/11/28 03:18:00 guenther Exp $ */
/*
* Copyright (c) 1998 Per Fogelstrom, Opsycon AB
@@ -50,6 +50,7 @@ struct symlookup {
const elf_object_t *sl_weak_obj_out;
const Elf_Sym *sl_weak_sym_out;
unsigned long sl_elf_hash;
+ uint32_t sl_gnu_hash;
int sl_flags;
};
@@ -261,6 +262,7 @@ _dl_finalize_object(const char *objname, Elf_Dyn *dynp, Elf_Phdr *phdrp,
int phdrc, const int objtype, const long lbase, const long obase)
{
elf_object_t *object;
+ Elf_Addr gnu_hash = 0;
#if 0
_dl_printf("objname [%s], dynp %p, objtype %x lbase %lx, obase %lx\n",
@@ -302,6 +304,8 @@ _dl_finalize_object(const char *objname, Elf_Dyn *dynp, Elf_Phdr *phdrp,
object->relacount = dynp->d_un.d_val;
if (dynp->d_tag == DT_RELCOUNT)
object->relcount = dynp->d_un.d_val;
+ if (dynp->d_tag == DT_GNU_HASH)
+ gnu_hash = dynp->d_un.d_val;
dynp++;
}
DL_DEB((" flags %s = 0x%x\n", objname, object->obj_flags ));
@@ -329,8 +333,6 @@ _dl_finalize_object(const char *objname, Elf_Dyn *dynp, Elf_Phdr *phdrp,
*/
if (object->Dyn.info[DT_PLTGOT])
object->Dyn.info[DT_PLTGOT] += obase;
- if (object->Dyn.info[DT_HASH])
- object->Dyn.info[DT_HASH] += obase;
if (object->Dyn.info[DT_STRTAB])
object->Dyn.info[DT_STRTAB] += obase;
if (object->Dyn.info[DT_SYMTAB])
@@ -358,13 +360,59 @@ _dl_finalize_object(const char *objname, Elf_Dyn *dynp, Elf_Phdr *phdrp,
if (object->Dyn.info[DT_PREINIT_ARRAY])
object->Dyn.info[DT_PREINIT_ARRAY] += obase;
+ if (gnu_hash) {
+ Elf32_Word *hashtab = (Elf32_Word *)(gnu_hash + obase);
+ Elf32_Word nbuckets = hashtab[0];
+ Elf32_Word nmaskwords = hashtab[2];
+
+ /* validity check */
+ if (nbuckets > 0 && (nmaskwords & (nmaskwords - 1)) == 0) {
+ Elf32_Word symndx = hashtab[1];
+ int bloom_size32 = (ELFSIZE / 32) * nmaskwords;
+
+ object->nbuckets = nbuckets;
+ object->symndx_gnu = symndx;
+ object->mask_bm_gnu = nmaskwords - 1;
+ object->shift2_gnu = hashtab[3];
+ object->bloom_gnu = (Elf_Addr *)(hashtab + 4);
+ object->buckets_gnu = hashtab + 4 + bloom_size32;
+ object->chains_gnu = object->buckets_gnu + nbuckets
+ - symndx;
+
+ /*
+ * If the ELF hash is present, get the total symbol
+ * count ("nchains") from there. Otherwise, count
+ * the entries in the GNU hash chain.
+ */
+ if (object->Dyn.info[DT_HASH] == 0) {
+ Elf32_Word n;
+
+ for (n = 0; n < nbuckets; n++) {
+ Elf_Word bkt = object->buckets_gnu[n];
+ const Elf32_Word *hashval;
+ if (bkt == 0)
+ continue;
+ hashval = &object->chains_gnu[bkt];
+ do {
+ symndx++;
+ } while ((*hashval++ & 1U) == 0);
+ }
+ object->nchains = symndx;
+ }
+ object->status |= STAT_GNU_HASH;
+ }
+ }
if (object->Dyn.info[DT_HASH] != 0) {
- Elf_Word *hashtab = (Elf_Word *)object->Dyn.info[DT_HASH];
+ Elf_Word *hashtab = (Elf_Word *)(object->Dyn.info[DT_HASH]
+ + obase);
- object->nbuckets = hashtab[0];
object->nchains = hashtab[1];
- object->buckets = hashtab + 2;
- object->chains = object->buckets + object->nbuckets;
+ if (object->nbuckets == 0) {
+ object->nbuckets = hashtab[0];
+ object->buckets_elf = hashtab + 2;
+ object->chains_elf = object->buckets_elf +
+ object->nbuckets;
+ }
}
object->phdrp = phdrp;
@@ -579,15 +627,53 @@ static int
_dl_find_symbol_obj(elf_object_t *obj, struct symlookup *sl)
{
const Elf_Sym *symt = obj->dyn.symtab;
- long si;
- for (si = obj->buckets[sl->sl_elf_hash % obj->nbuckets];
- si != STN_UNDEF; si = obj->chains[si]) {
- const Elf_Sym *sym = symt + si;
+ if (obj->status & STAT_GNU_HASH) {
+ uint32_t hash = sl->sl_gnu_hash;
+ Elf_Addr bloom_word;
+ unsigned int h1;
+ unsigned int h2;
+ Elf32_Word bucket;
+ const Elf32_Word *hashval;
+
+ /* pick right bitmask word from Bloom filter array */
+ bloom_word = obj->bloom_gnu[(hash / ELFSIZE) &
+ obj->mask_bm_gnu];
+
+ /* calculate modulus ELFSIZE of gnu hash and its derivative */
+ h1 = hash & (ELFSIZE - 1);
+ h2 = (hash >> obj->shift2_gnu) & (ELFSIZE - 1);
- int r = matched_symbol(obj, sym, sl);
- if (r)
- return r > 0;
+ /* Filter out the "definitely not in set" queries */
+ if (((bloom_word >> h1) & (bloom_word >> h2) & 1) == 0)
+ return 0;
+
+ /* Locate hash chain and corresponding value element */
+ bucket = obj->buckets_gnu[hash % obj->nbuckets];
+ if (bucket == 0)
+ return 0;
+ hashval = &obj->chains_gnu[bucket];
+ do {
+ if (((*hashval ^ hash) >> 1) == 0) {
+ const Elf_Sym *sym = symt +
+ (hashval - obj->chains_gnu);
+
+ int r = matched_symbol(obj, sym, sl);
+ if (r)
+ return r > 0;
+ }
+ } while ((*hashval++ & 1U) == 0);
+ } else {
+ Elf_Word si;
+
+ for (si = obj->buckets_elf[sl->sl_elf_hash % obj->nbuckets];
+ si != STN_UNDEF; si = obj->chains_elf[si]) {
+ const Elf_Sym *sym = symt + si;
+
+ int r = matched_symbol(obj, sym, sl);
+ if (r)
+ return r > 0;
+ }
}
return 0;
}
@@ -597,7 +683,8 @@ _dl_find_symbol(const char *name, const Elf_Sym **this,
int flags, const Elf_Sym *ref_sym, elf_object_t *req_obj,
const elf_object_t **pobj)
{
- const char *p = name;
+ const unsigned char *p;
+ unsigned char c;
struct dep_node *n, *m;
struct symlookup sl = {
.sl_name = name,
@@ -605,15 +692,18 @@ _dl_find_symbol(const char *name, const Elf_Sym **this,
.sl_weak_obj_out = NULL,
.sl_weak_sym_out = NULL,
.sl_elf_hash = 0,
+ .sl_gnu_hash = 5381,
.sl_flags = flags,
};
- while (*p) {
+ /* Calculate both hashes in one pass */
+ for (p = (const unsigned char *)name; (c = *p) != '\0'; p++) {
unsigned long g;
- sl.sl_elf_hash = (sl.sl_elf_hash << 4) + *p++;
+ sl.sl_elf_hash = (sl.sl_elf_hash << 4) + c;
if ((g = sl.sl_elf_hash & 0xf0000000))
sl.sl_elf_hash ^= g >> 24;
sl.sl_elf_hash &= ~g;
+ sl.sl_gnu_hash = sl.sl_gnu_hash * 33 + c;
}
if (req_obj->dyn.symbolic)
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.