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bh_elf.c
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bh_elf.c
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// Copyright (c) 2020-present, ByteDance, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//
// Created by Kelun Cai (caikelun@bytedance.com) on 2020-06-02.
#include <unistd.h>
#include <stdint.h>
#include <stdlib.h>
#include <inttypes.h>
#include <dlfcn.h>
#include <link.h>
#include <elf.h>
#include <string.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <pthread.h>
#include "bh_elf.h"
#include "bh_sleb128.h"
#include "bh_util.h"
#include "bh_log.h"
#include "bytesig.h"
#define MAYBE_MAP_FLAG(x, from, to) (((x) & (from)) ? (to) : 0)
#define PFLAGS_TO_PROT(x) (MAYBE_MAP_FLAG((x), PF_X, PROT_EXEC) | \
MAYBE_MAP_FLAG((x), PF_R, PROT_READ) | \
MAYBE_MAP_FLAG((x), PF_W, PROT_WRITE))
#define BH_ELF_IS_IMPORT_SYM(shndx) (SHN_UNDEF == (shndx))
#define BH_ELF_IS_EXPORT_SYM(shndx) (SHN_UNDEF != (shndx)) //this is enough for .dynsym
#if defined(__arm__)
#define BH_ELF_R_JUMP_SLOT R_ARM_JUMP_SLOT //.rel.plt
#define BH_ELF_R_GLOB_DAT R_ARM_GLOB_DAT //.rel.dyn
#define BH_ELF_R_ABS R_ARM_ABS32 //.rel.dyn
#elif defined(__aarch64__)
#define BH_ELF_R_JUMP_SLOT R_AARCH64_JUMP_SLOT
#define BH_ELF_R_GLOB_DAT R_AARCH64_GLOB_DAT
#define BH_ELF_R_ABS R_AARCH64_ABS64
#elif defined(__i386__)
#define BH_ELF_R_JUMP_SLOT R_386_JMP_SLOT
#define BH_ELF_R_GLOB_DAT R_386_GLOB_DAT
#define BH_ELF_R_ABS R_386_32
#elif defined(__x86_64__)
#define BH_ELF_R_JUMP_SLOT R_X86_64_JUMP_SLOT
#define BH_ELF_R_GLOB_DAT R_X86_64_GLOB_DAT
#define BH_ELF_R_ABS R_X86_64_64
#endif
#if defined(__LP64__)
#define BH_ELF_R_SYM(info) ELF64_R_SYM(info)
#define BH_ELF_R_TYPE(info) ELF64_R_TYPE(info)
#else
#define BH_ELF_R_SYM(info) ELF32_R_SYM(info)
#define BH_ELF_R_TYPE(info) ELF32_R_TYPE(info)
#endif
#define RELOCATION_GROUPED_BY_INFO_FLAG ((size_t)1)
#define RELOCATION_GROUPED_BY_OFFSET_DELTA_FLAG ((size_t)2)
#if defined(__LP64__)
#define RELOCATION_GROUPED_BY_ADDEND_FLAG ((size_t)4)
#endif
#define RELOCATION_GROUP_HAS_ADDEND_FLAG ((size_t)8)
static void bh_elf_iterate_aps2(bh_sleb128_decoder_t *decoder, bool (*callback)(Elf_Reloc *, void *), void *arg)
{
size_t num_relocs;
if(0 != bh_sleb128_decoder_next(decoder, &num_relocs)) return;
Elf_Reloc reloc;
if(0 != bh_sleb128_decoder_next(decoder, (size_t *)&reloc.r_offset)) return;
for(size_t idx = 0; idx < num_relocs;)
{
size_t group_size;
if(0 != bh_sleb128_decoder_next(decoder, &group_size)) return;
size_t group_flags;
if(0 != bh_sleb128_decoder_next(decoder, &group_flags)) return;
size_t group_r_offset_delta = 0;
if(group_flags & RELOCATION_GROUPED_BY_OFFSET_DELTA_FLAG)
{
if(0 != bh_sleb128_decoder_next(decoder, &group_r_offset_delta)) return;
}
if(group_flags & RELOCATION_GROUPED_BY_INFO_FLAG)
{
if(0 != bh_sleb128_decoder_next(decoder, (size_t *)&reloc.r_info)) return;
}
#if defined(__LP64__)
const size_t group_flags_reloc = group_flags & (RELOCATION_GROUP_HAS_ADDEND_FLAG | RELOCATION_GROUPED_BY_ADDEND_FLAG);
if(group_flags_reloc == (RELOCATION_GROUP_HAS_ADDEND_FLAG | RELOCATION_GROUPED_BY_ADDEND_FLAG))
{
size_t val;
if(0 != bh_sleb128_decoder_next(decoder, &val)) return;
reloc.r_addend += val;
}
else
{
reloc.r_addend = 0;
}
#else
if(__predict_false(group_flags & RELOCATION_GROUP_HAS_ADDEND_FLAG)) return;
#endif
for(size_t i = 0; i < group_size; i++)
{
if(group_flags & RELOCATION_GROUPED_BY_OFFSET_DELTA_FLAG)
{
reloc.r_offset += group_r_offset_delta;
}
else
{
size_t val;
if(0 != bh_sleb128_decoder_next(decoder, &val)) return;
reloc.r_offset += val;
}
if((group_flags & RELOCATION_GROUPED_BY_INFO_FLAG) == 0)
{
if(0 != bh_sleb128_decoder_next(decoder, (size_t *)&reloc.r_info)) return;
}
#if defined(__LP64__)
if (group_flags_reloc == RELOCATION_GROUP_HAS_ADDEND_FLAG)
{
size_t val;
if(0 != bh_sleb128_decoder_next(decoder, &val)) return;
reloc.r_addend += val;
}
#endif
if(!callback(&reloc, arg)) return;
}
idx += group_size;
}
}
static void bh_elf_parse_dynamic_unsafe(bh_elf_t *self, ElfW(Dyn) *dynamic)
{
// iterate the dynamic segment
for(ElfW(Dyn) * entry = dynamic; entry && entry->d_tag != DT_NULL; entry++)
{
switch (entry->d_tag)
{
//.rel.plt / .rela.plt
case DT_JMPREL:
self->rel_plt = (const Elf_Reloc *)(self->load_bias + entry->d_un.d_ptr);
break;
case DT_PLTRELSZ:
self->rel_plt_cnt = (size_t)entry->d_un.d_val / sizeof(Elf_Reloc);
break;
//.rel.dyn / .rela.dyn
case DT_REL:
case DT_RELA:
self->rel_dyn = (const Elf_Reloc *)(self->load_bias + entry->d_un.d_ptr);
break;
case DT_RELSZ:
case DT_RELASZ:
self->rel_dyn_cnt = (size_t)entry->d_un.d_val / sizeof(Elf_Reloc);
break;
//.rel.dyn / .rela.dyn (APS2 format)
case DT_ANDROID_REL:
case DT_ANDROID_RELA:
self->rel_dyn_aps2 = (uint8_t *)(self->load_bias + entry->d_un.d_ptr);
break;
case DT_ANDROID_RELSZ:
case DT_ANDROID_RELASZ:
self->rel_dyn_aps2_sz = (size_t)entry->d_un.d_val;
break;
//.dynsym
case DT_SYMTAB:
self->dynsym = (ElfW(Sym) *)(self->load_bias + entry->d_un.d_ptr);
break;
//.dynstr
case DT_STRTAB:
self->dynstr = (const char *)(self->load_bias + entry->d_un.d_ptr);
break;
//.hash
case DT_HASH:
self->sysv_hash.buckets_cnt = ((const uint32_t *)(self->load_bias + entry->d_un.d_ptr))[0];
self->sysv_hash.chains_cnt = ((const uint32_t *)(self->load_bias + entry->d_un.d_ptr))[1];
self->sysv_hash.buckets = &(((const uint32_t *)(self->load_bias + entry->d_un.d_ptr))[2]);
self->sysv_hash.chains = &(self->sysv_hash.buckets[self->sysv_hash.buckets_cnt]);
break;
//.gnu.hash
case DT_GNU_HASH:
self->gnu_hash.buckets_cnt = ((const uint32_t *)(self->load_bias + entry->d_un.d_ptr))[0];
self->gnu_hash.symoffset = ((const uint32_t *)(self->load_bias + entry->d_un.d_ptr))[1];
self->gnu_hash.bloom_cnt = ((const uint32_t *)(self->load_bias + entry->d_un.d_ptr))[2];
self->gnu_hash.bloom_shift = ((const uint32_t *)(self->load_bias + entry->d_un.d_ptr))[3];
self->gnu_hash.bloom = (const ElfW(Addr) *)(self->load_bias + entry->d_un.d_ptr + 16);
self->gnu_hash.buckets = (const uint32_t *)(&(self->gnu_hash.bloom[self->gnu_hash.bloom_cnt]));
self->gnu_hash.chains = (const uint32_t *)(&(self->gnu_hash.buckets[self->gnu_hash.buckets_cnt]));
break;
default:
break;
}
}
// check and fix APS2
if(NULL != self->rel_dyn_aps2)
{
char *rel = (char *)self->rel_dyn_aps2;
if(self->rel_dyn_aps2_sz < 4 || rel[0] != 'A' || rel[1] != 'P' || rel[2] != 'S' || rel[3] != '2')
{
self->rel_dyn_aps2 = 0;
self->rel_dyn_aps2_sz = 0;
}
else
{
self->rel_dyn_aps2 += 4;
self->rel_dyn_aps2_sz -= 4;
}
}
}
static int bh_elf_parse_dynamic(bh_elf_t *self)
{
if(self->error) return -1;
if(self->dyn_parsed) return 0;
pthread_mutex_lock(&self->dyn_parse_lock);
if(!self->dyn_parsed)
{
self->dyn_parsed = true;
BYTESIG_TRY(SIGSEGV, SIGBUS)
{
ElfW(Dyn) *dynamic = NULL;
for(size_t i = 0; i < self->dlpi_phnum; i++)
{
if(self->dlpi_phdr[i].p_type == PT_DYNAMIC)
{
dynamic = (ElfW(Dyn) *)(self->load_bias + self->dlpi_phdr[i].p_vaddr);
break;
}
}
if(NULL == dynamic)
self->error = true;
else
bh_elf_parse_dynamic_unsafe(self, dynamic);
}
BYTESIG_CATCH()
self->error = true;
BYTESIG_EXIT
}
pthread_mutex_unlock(&self->dyn_parse_lock);
return self->error ? -1 : 0;
}
bh_elf_t *bh_elf_create(struct dl_phdr_info *info)
{
if(0 == info->dlpi_phdr || NULL == info->dlpi_name || NULL == info->dlpi_phdr || 0 == info->dlpi_phnum) return NULL;
bh_elf_t *self;
if(NULL == (self = calloc(1, sizeof(bh_elf_t)))) return NULL;
if(NULL == (self->pathname = strdup(info->dlpi_name)))
{
free(self);
return NULL;
}
self->exist = false;
pthread_mutex_init(&self->hook_lock, NULL);
self->error = false;
#ifdef __LP64__
self->cfi_hooked = false;
self->cfi_hooked_ok = false;
pthread_mutex_init(&self->cfi_hook_lock, NULL);
#endif
self->load_bias = info->dlpi_addr;
self->dlpi_phdr = info->dlpi_phdr;
self->dlpi_phnum = info->dlpi_phnum;
self->dyn_parsed = false;
pthread_mutex_init(&self->dyn_parse_lock, NULL);
return self;
}
void bh_elf_destroy(bh_elf_t **self)
{
if(NULL == self || NULL == *self) return;
pthread_mutex_destroy(&(*self)->hook_lock);
pthread_mutex_destroy(&(*self)->dyn_parse_lock);
if(NULL != (*self)->pathname) free((void *)(uintptr_t)(*self)->pathname);
free(*self);
*self = NULL;
}
bool bh_elf_is_match(bh_elf_t *self, const char *name)
{
if('/' == self->pathname[0] && '/' != name[0])
return bh_util_ends_with(self->pathname, name);
else if('/' != self->pathname[0] && '/' == name[0])
return bh_util_ends_with(name, self->pathname);
else
return 0 == strcmp(self->pathname, name);
}
bool bh_elf_get_error(bh_elf_t *self)
{
return self->error;
}
void bh_elf_set_error(bh_elf_t *self, bool error)
{
self->error = error;
}
#ifdef __LP64__
void bh_elf_cfi_hook_lock(bh_elf_t *self)
{
pthread_mutex_lock(&self->cfi_hook_lock);
}
void bh_elf_cfi_hook_unlock(bh_elf_t *self)
{
pthread_mutex_unlock(&self->cfi_hook_lock);
}
#endif
void bh_elf_hook_lock(bh_elf_t *self)
{
pthread_mutex_lock(&self->hook_lock);
}
void bh_elf_hook_unlock(bh_elf_t *self)
{
pthread_mutex_unlock(&self->hook_lock);
}
void bh_elf_set_exist(bh_elf_t *self)
{
self->exist = true;
}
void bh_elf_unset_exist(bh_elf_t *self)
{
self->exist = false;
}
bool bh_elf_is_exist(bh_elf_t *self)
{
return self->exist;
}
static int bh_elf_get_protect_by_addr_unsafe(bh_elf_t *self, void *addr)
{
for(size_t i = 0; i < self->dlpi_phnum; i++)
{
const ElfW(Phdr) *phdr = &(self->dlpi_phdr[i]);
if(self->dlpi_phdr[i].p_type == PT_GNU_RELRO)
if((uintptr_t)addr >= (self->load_bias + phdr->p_vaddr) && (uintptr_t)addr < (self->load_bias + phdr->p_vaddr + phdr->p_memsz))
return PROT_READ;
}
for(size_t i = 0; i < self->dlpi_phnum; i++)
{
const ElfW(Phdr) *phdr = &(self->dlpi_phdr[i]);
if(self->dlpi_phdr[i].p_type == PT_LOAD)
if((uintptr_t)addr >= (self->load_bias + phdr->p_vaddr) && (uintptr_t)addr < (self->load_bias + phdr->p_vaddr + phdr->p_memsz))
return PFLAGS_TO_PROT(phdr->p_flags);
}
return 0;
}
int bh_elf_get_protect_by_addr(bh_elf_t *self, void *addr)
{
int prot = 0;
BYTESIG_TRY(SIGSEGV, SIGBUS)
prot = bh_elf_get_protect_by_addr_unsafe(self, addr);
BYTESIG_CATCH()
self->error = true;
BYTESIG_EXIT
return prot;
}
static uint32_t bh_elf_sysv_hash(const uint8_t *name)
{
uint32_t h = 0, g;
while(*name)
{
h = (h << 4) + *name++;
g = h & 0xf0000000;
h ^= g;
h ^= g >> 24;
}
return h;
}
static uint32_t bh_elf_gnu_hash(const uint8_t *name)
{
uint32_t h = 5381;
while(*name)
{
h += (h << 5) + *name++;
}
return h;
}
static ElfW(Sym) *bh_elf_find_symbol_by_name_use_sysv_hash(bh_elf_t *self, const char* sym_name)
{
uint32_t hash = bh_elf_sysv_hash((const uint8_t *)sym_name);
for(uint32_t i = self->sysv_hash.buckets[hash % self->sysv_hash.buckets_cnt]; 0 != i; i = self->sysv_hash.chains[i])
{
ElfW(Sym) *sym = self->dynsym + i;
unsigned char type = ELF_ST_TYPE(sym->st_info);
if(STT_FUNC != type && STT_GNU_IFUNC != type && STT_NOTYPE != type) continue; // find function only, allow no-type
if(0 != strcmp(self->dynstr + sym->st_name, sym_name)) continue;
return sym;
}
return NULL;
}
static ElfW(Sym) *bh_elf_find_symbol_by_name_use_gnu_hash(bh_elf_t *self, const char* sym_name)
{
uint32_t hash = bh_elf_gnu_hash((const uint8_t *)sym_name);
static uint32_t elfclass_bits = sizeof(ElfW(Addr)) * 8;
size_t word = self->gnu_hash.bloom[(hash / elfclass_bits) % self->gnu_hash.bloom_cnt];
size_t mask = 0 | (size_t)1 << (hash % elfclass_bits)
| (size_t)1 << ((hash >> self->gnu_hash.bloom_shift) % elfclass_bits);
//if at least one bit is not set, this symbol is surely missing
if((word & mask) != mask) return NULL;
//ignore STN_UNDEF
uint32_t i = self->gnu_hash.buckets[hash % self->gnu_hash.buckets_cnt];
if(i < self->gnu_hash.symoffset) return NULL;
//loop through the chain
while(1)
{
ElfW(Sym) *sym = self->dynsym + i;
unsigned char type = ELF_ST_TYPE(sym->st_info);
uint32_t sym_hash = self->gnu_hash.chains[i - self->gnu_hash.symoffset];
if((hash | (uint32_t)1) == (sym_hash | (uint32_t)1) &&
(STT_FUNC == type || STT_GNU_IFUNC == type || STT_NOTYPE == type) && // find function only, allow no-type
0 == strcmp(self->dynstr + sym->st_name, sym_name))
{
return sym;
}
//chain ends with an element with the lowest bit set to 1
if(sym_hash & (uint32_t)1) break;
i++;
}
return NULL;
}
static ElfW(Sym) *bh_elf_find_symbol_by_name_use_import_table(bh_elf_t *self, const char* sym_name)
{
for(size_t i = 0; i < self->gnu_hash.symoffset; i++)
{
ElfW(Sym) *sym = self->dynsym + i;
unsigned char type = ELF_ST_TYPE(sym->st_info);
if(STT_FUNC != type && STT_NOTYPE != type) continue; // find function only, allow no-type
if(0 != strcmp(self->dynstr + sym->st_name, sym_name)) continue;
return sym;
}
return NULL;
}
static ElfW(Sym) *bh_elf_find_import_func_symbol_by_symbol_name(bh_elf_t *self, const char *sym_name)
{
ElfW(Sym) *sym;
// from SYSV hash (.hash -> .dynsym -> .dynstr), O(x) + O(1) + O(1)
if(self->sysv_hash.buckets_cnt > 0)
{
sym = bh_elf_find_symbol_by_name_use_sysv_hash(self, sym_name);
if(NULL != sym && BH_ELF_IS_IMPORT_SYM(sym->st_shndx)) return sym;
}
// from import table's linear search (.dynsym -> .dynstr), O(n) + O(1)
if(self->gnu_hash.symoffset > 0)
{
sym = bh_elf_find_symbol_by_name_use_import_table(self, sym_name);
if(NULL != sym && BH_ELF_IS_IMPORT_SYM(sym->st_shndx)) return sym;
}
// .gnu.hash only contains the exported functions of ELF. If there is only .gnu.hash in ELF,
// and the caller and callee of the hook function are the same ELF,
// and this function also exists in the export table of ELF, you can find it through .gnu.hash.
//
// from GNU hash (.gnu.hash -> .dynsym -> .dynstr), O(x) + O(1) + O(1)
if(self->gnu_hash.buckets_cnt > 0)
{
sym = bh_elf_find_symbol_by_name_use_gnu_hash(self, sym_name);
if(NULL != sym && BH_ELF_IS_EXPORT_SYM(sym->st_shndx)) return sym;
}
// PLT that is only used internally may not be included in the .hash or .gnu.hash.
//
// from .rel.plt and .rel.dyn, O(n)
for(size_t i = 0; i < self->rel_plt_cnt; i++)
{
size_t sym_idx = BH_ELF_R_SYM(self->rel_plt[i].r_info);
if(0 == strcmp(self->dynstr + self->dynsym[sym_idx].st_name, sym_name)) return &self->dynsym[sym_idx];
}
for(size_t i = 0; i < self->rel_dyn_cnt; i++)
{
size_t sym_idx = BH_ELF_R_SYM(self->rel_dyn[i].r_info);
if(0 == strcmp(self->dynstr + self->dynsym[sym_idx].st_name, sym_name)) return &self->dynsym[sym_idx];
}
return NULL;
}
static ElfW(Sym) *bh_elf_find_export_func_symbol_by_symbol_name_unsafe(bh_elf_t *self, const char *sym_name)
{
ElfW(Sym) *sym = NULL;
// from GNU hash (.gnu.hash -> .dynsym -> .dynstr), O(x) + O(1) + O(1)
if(self->gnu_hash.buckets_cnt > 0)
{
sym = bh_elf_find_symbol_by_name_use_gnu_hash(self, sym_name);
if(NULL != sym && BH_ELF_IS_EXPORT_SYM(sym->st_shndx)) return sym;
}
// from SYSV hash (.hash -> .dynsym -> .dynstr), O(x) + O(1) + O(1)
if(self->sysv_hash.buckets_cnt > 0)
{
sym = bh_elf_find_symbol_by_name_use_sysv_hash(self, sym_name);
if(NULL != sym && BH_ELF_IS_EXPORT_SYM(sym->st_shndx)) return sym;
}
return NULL;
}
ElfW(Sym) *bh_elf_find_export_func_symbol_by_symbol_name(bh_elf_t *self, const char *sym_name)
{
if(self->error) return NULL;
if(0 != bh_elf_parse_dynamic(self)) return NULL;
ElfW(Sym) *sym = NULL;
BYTESIG_TRY(SIGSEGV, SIGBUS)
sym = bh_elf_find_export_func_symbol_by_symbol_name_unsafe(self, sym_name);
BYTESIG_CATCH()
self->error = true;
sym = NULL;
BYTESIG_EXIT
return sym;
}
static bool bh_elf_find_import_func_addr_by_symbol_name_unsafe_aps2_cb(Elf_Reloc *rel, void *arg)
{
void **pkg = (void **)arg;
bh_elf_t *self = (bh_elf_t *)*pkg++;
const ElfW(Sym) *sym = (const ElfW(Sym) *)*pkg++;
void **addr_array = (void **)*pkg++;
size_t addr_array_cap = (size_t)*pkg++;
size_t *addr_array_sz = (size_t *)*pkg;
if(&(self->dynsym[BH_ELF_R_SYM(rel->r_info)]) != sym) return true;
if(BH_ELF_R_GLOB_DAT != BH_ELF_R_TYPE(rel->r_info) && BH_ELF_R_ABS != BH_ELF_R_TYPE(rel->r_info)) return true;
addr_array[(*addr_array_sz)++] = (void *)(self->load_bias + rel->r_offset);
return *addr_array_sz < addr_array_cap;
}
static size_t bh_elf_find_import_func_addr_by_symbol_name_unsafe(bh_elf_t *self, const char *sym_name, void **addr_array, size_t addr_array_cap)
{
size_t addr_array_sz = 0;
ElfW(Sym) *sym = bh_elf_find_import_func_symbol_by_symbol_name(self, sym_name);
if(NULL == sym) return 0;
for(size_t i = 0; i < self->rel_plt_cnt; i++)
{
const Elf_Reloc *rel = &(self->rel_plt[i]);
if(&(self->dynsym[BH_ELF_R_SYM(rel->r_info)]) != sym) continue;
if(BH_ELF_R_JUMP_SLOT != BH_ELF_R_TYPE(rel->r_info)) continue;
addr_array[addr_array_sz++] = (void *)(self->load_bias + rel->r_offset);
if(addr_array_sz >= addr_array_cap) return addr_array_sz;
}
for(size_t i = 0; i < self->rel_dyn_cnt; i++)
{
const Elf_Reloc *rel = &(self->rel_dyn[i]);
if(&(self->dynsym[BH_ELF_R_SYM(rel->r_info)]) != sym) continue;
if(BH_ELF_R_GLOB_DAT != BH_ELF_R_TYPE(rel->r_info) && BH_ELF_R_ABS != BH_ELF_R_TYPE(rel->r_info)) continue;
addr_array[addr_array_sz++] = (void *)(self->load_bias + rel->r_offset);
if(addr_array_sz >= addr_array_cap) return addr_array_sz;
}
if(NULL != self->rel_dyn_aps2)
{
bh_sleb128_decoder_t decoder;
bh_sleb128_decoder_init(&decoder, self->rel_dyn_aps2, self->rel_dyn_aps2_sz);
void *pkg[5] = {self, sym, (void *)addr_array, (void *)addr_array_cap, &addr_array_sz};
bh_elf_iterate_aps2(&decoder, bh_elf_find_import_func_addr_by_symbol_name_unsafe_aps2_cb, pkg);
}
return addr_array_sz;
}
size_t bh_elf_find_import_func_addr_by_symbol_name(bh_elf_t *self, const char *sym_name, void **addr_array, size_t addr_array_cap)
{
if(self->error) return 0;
if(0 != bh_elf_parse_dynamic(self)) return 0;
size_t addr_array_sz = 0;
BYTESIG_TRY(SIGSEGV, SIGBUS)
addr_array_sz = bh_elf_find_import_func_addr_by_symbol_name_unsafe(self, sym_name, addr_array, addr_array_cap);
BYTESIG_CATCH()
self->error = true;
addr_array_sz = 0;
BYTESIG_EXIT
return addr_array_sz;
}
static bool bh_elf_find_import_func_addr_by_callee_addr_unsafe_aps2_cb(Elf_Reloc *rel, void *arg)
{
void **pkg = (void **)arg;
bh_elf_t *self = (bh_elf_t *)*pkg++;
void *target_addr = *pkg++;
void **addr_array = (void **)*pkg++;
size_t addr_array_cap = (size_t)*pkg++;
size_t *addr_array_sz = (size_t *)*pkg;
if(BH_ELF_R_GLOB_DAT != BH_ELF_R_TYPE(rel->r_info) && BH_ELF_R_ABS != BH_ELF_R_TYPE(rel->r_info)) return true;
if(*((void **)(self->load_bias + rel->r_offset)) != target_addr) return true;
addr_array[(*addr_array_sz)++] = (void *)(self->load_bias + rel->r_offset);
return *addr_array_sz < addr_array_cap;
}
static size_t bh_elf_find_import_func_addr_by_callee_addr_unsafe(bh_elf_t *self, void *target_addr, void **addr_array, size_t addr_array_cap)
{
size_t addr_array_sz = 0;
for(size_t i = 0; i < self->rel_plt_cnt; i++)
{
const Elf_Reloc *rel = &(self->rel_plt[i]);
if(BH_ELF_R_JUMP_SLOT != BH_ELF_R_TYPE(rel->r_info)) continue;
if(*((void **)(self->load_bias + rel->r_offset)) != target_addr) continue;
addr_array[addr_array_sz++] = (void *)(self->load_bias + rel->r_offset);
if(addr_array_sz >= addr_array_cap) return addr_array_sz;
}
for(size_t i = 0; i < self->rel_dyn_cnt; i++)
{
const Elf_Reloc *rel = &(self->rel_dyn[i]);
if(BH_ELF_R_GLOB_DAT != BH_ELF_R_TYPE(rel->r_info) && BH_ELF_R_ABS != BH_ELF_R_TYPE(rel->r_info)) continue;
if(*((void **)(self->load_bias + rel->r_offset)) != target_addr) continue;
addr_array[addr_array_sz++] = (void *)(self->load_bias + rel->r_offset);
if(addr_array_sz >= addr_array_cap) return addr_array_sz;
}
if(NULL != self->rel_dyn_aps2)
{
bh_sleb128_decoder_t decoder;
bh_sleb128_decoder_init(&decoder, self->rel_dyn_aps2, self->rel_dyn_aps2_sz);
void *pkg[5] = {self, target_addr, (void *)addr_array, (void *)addr_array_cap, &addr_array_sz};
bh_elf_iterate_aps2(&decoder, bh_elf_find_import_func_addr_by_callee_addr_unsafe_aps2_cb, pkg);
}
return addr_array_sz;
}
size_t bh_elf_find_import_func_addr_by_callee_addr(bh_elf_t *self, void *target_addr, void **addr_array, size_t addr_array_cap)
{
if(self->error) return 0;
if(0 != bh_elf_parse_dynamic(self)) return 0;
size_t addr_array_sz;
BYTESIG_TRY(SIGSEGV, SIGBUS)
addr_array_sz = bh_elf_find_import_func_addr_by_callee_addr_unsafe(self, target_addr, addr_array, addr_array_cap);
BYTESIG_CATCH()
self->error = true;
addr_array_sz = 0;
BYTESIG_EXIT
return addr_array_sz;
}
static void *bh_elf_find_export_func_addr_by_symbol_name_unsafe(bh_elf_t *self, const char* sym_name)
{
ElfW(Sym) *sym = bh_elf_find_export_func_symbol_by_symbol_name_unsafe(self, sym_name);
if(NULL == sym) return NULL;
return (void *)(self->load_bias + sym->st_value);
}
void *bh_elf_find_export_func_addr_by_symbol_name(bh_elf_t *self, const char* sym_name)
{
if(self->error) return NULL;
if(0 != bh_elf_parse_dynamic(self)) return NULL;
void *addr = NULL;
BYTESIG_TRY(SIGSEGV, SIGBUS)
addr = bh_elf_find_export_func_addr_by_symbol_name_unsafe(self, sym_name);
BYTESIG_CATCH()
self->error = true;
addr = NULL;
BYTESIG_EXIT
return addr;
}