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-rw-r--r--linker/dlfcn.cpp2
-rwxr-xr-xlinker/linker.cpp222
-rw-r--r--linker/linker.h13
-rw-r--r--linker/linker_debug.h6
-rw-r--r--linker/linker_phdr.cpp464
-rw-r--r--linker/linker_phdr.h67
6 files changed, 317 insertions, 457 deletions
diff --git a/linker/dlfcn.cpp b/linker/dlfcn.cpp
index 0603d40..0b38ec4 100644
--- a/linker/dlfcn.cpp
+++ b/linker/dlfcn.cpp
@@ -64,7 +64,7 @@ void* dlopen(const char* filename, int flags) {
ScopedPthreadMutexLocker locker(&gDlMutex);
soinfo* result = do_dlopen(filename, flags);
if (result == NULL) {
- __bionic_format_dlerror("dlopen failed", linker_get_error());
+ __bionic_format_dlerror("dlopen failed", linker_get_error_buffer());
return NULL;
}
return result;
diff --git a/linker/linker.cpp b/linker/linker.cpp
index e08eaba..f18443c 100755
--- a/linker/linker.cpp
+++ b/linker/linker.cpp
@@ -41,7 +41,6 @@
// Private C library headers.
#include <private/bionic_tls.h>
-#include <private/debug_format.h>
#include <private/KernelArgumentBlock.h>
#include <private/logd.h>
#include <private/ScopedPthreadMutexLocker.h>
@@ -105,7 +104,7 @@ static const char* gLdPreloadNames[LDPRELOAD_MAX + 1];
static soinfo* gLdPreloads[LDPRELOAD_MAX + 1];
-static int debug_verbosity;
+__LIBC_HIDDEN__ int gLdDebugVerbosity;
enum RelocationKind {
kRelocAbsolute = 0,
@@ -158,17 +157,15 @@ DISALLOW_ALLOCATION(void*, calloc, (size_t u1 UNUSED, size_t u2 UNUSED));
static char tmp_err_buf[768];
static char __linker_dl_err_buf[768];
-#define DL_ERR(fmt, x...) \
- do { \
- __libc_format_buffer(__linker_dl_err_buf, sizeof(__linker_dl_err_buf), fmt, ##x); \
- /* If LD_DEBUG is set high enough, send every dlerror(3) message to the log. */ \
- DEBUG(fmt "\n", ##x); \
- } while(0)
-const char* linker_get_error() {
+char* linker_get_error_buffer() {
return &__linker_dl_err_buf[0];
}
+size_t linker_get_error_buffer_size() {
+ return sizeof(__linker_dl_err_buf);
+}
+
/*
* This function is an empty stub where GDB locates a breakpoint to get notified
* about linker activity.
@@ -706,197 +703,34 @@ static int open_library(const char* name) {
return fd;
}
-// Returns 'true' if the library is prelinked or on failure so we error out
-// either way. We no longer support prelinking.
-static bool is_prelinked(int fd, const char* name)
-{
- struct prelink_info_t {
- long mmap_addr;
- char tag[4]; // "PRE ".
- };
-
- off_t sz = lseek(fd, -sizeof(prelink_info_t), SEEK_END);
- if (sz < 0) {
- DL_ERR("lseek failed: %s", strerror(errno));
- return true;
- }
-
- prelink_info_t info;
- int rc = TEMP_FAILURE_RETRY(read(fd, &info, sizeof(info)));
- if (rc != sizeof(info)) {
- DL_ERR("could not read prelink_info_t structure for \"%s\": %s", name, strerror(errno));
- return true;
- }
-
- if (memcmp(info.tag, "PRE ", 4) == 0) {
- DL_ERR("prelinked libraries no longer supported: %s", name);
- return true;
- }
- return false;
-}
-
-/* verify_elf_header
- * Verifies the content of an ELF header.
- *
- * Args:
- *
- * Returns:
- * 0 on success
- * -1 if no valid ELF object is found @ base.
- */
-static int
-verify_elf_header(const Elf32_Ehdr* hdr)
-{
- if (hdr->e_ident[EI_MAG0] != ELFMAG0) return -1;
- if (hdr->e_ident[EI_MAG1] != ELFMAG1) return -1;
- if (hdr->e_ident[EI_MAG2] != ELFMAG2) return -1;
- if (hdr->e_ident[EI_MAG3] != ELFMAG3) return -1;
- if (hdr->e_type != ET_DYN) return -1;
-
- /* TODO: Should we verify anything else in the header? */
-#ifdef ANDROID_ARM_LINKER
- if (hdr->e_machine != EM_ARM) return -1;
-#elif defined(ANDROID_X86_LINKER)
- if (hdr->e_machine != EM_386) return -1;
-#elif defined(ANDROID_MIPS_LINKER)
- if (hdr->e_machine != EM_MIPS) return -1;
-#endif
- return 0;
-}
-
-struct scoped_fd {
- ~scoped_fd() {
- if (fd != -1) {
- close(fd);
- }
- }
- int fd;
-};
-
-struct soinfo_ptr {
- soinfo_ptr(const char* name) {
- const char* bname = strrchr(name, '/');
- ptr = soinfo_alloc(bname ? bname + 1 : name);
- }
- ~soinfo_ptr() {
- soinfo_free(ptr);
- }
- soinfo* release() {
- soinfo* result = ptr;
- ptr = NULL;
- return result;
- }
- soinfo* ptr;
-};
-
-// TODO: rewrite linker_phdr.h to use a class, then lose this.
-struct phdr_ptr {
- phdr_ptr() : phdr_mmap(NULL) {}
- ~phdr_ptr() {
- if (phdr_mmap != NULL) {
- phdr_table_unload(phdr_mmap, phdr_size);
- }
- }
- void* phdr_mmap;
- Elf32_Addr phdr_size;
-};
-
static soinfo* load_library(const char* name) {
// Open the file.
- scoped_fd fd;
- fd.fd = open_library(name);
- if (fd.fd == -1) {
+ int fd = open_library(name);
+ if (fd == -1) {
DL_ERR("library \"%s\" not found", name);
return NULL;
}
- // Read the ELF header.
- Elf32_Ehdr header[1];
- int ret = TEMP_FAILURE_RETRY(read(fd.fd, (void*)header, sizeof(header)));
- if (ret < 0) {
- DL_ERR("can't read file \"%s\": %s", name, strerror(errno));
- return NULL;
- }
- if (ret != (int)sizeof(header)) {
- DL_ERR("too small to be an ELF executable: %s", name);
- return NULL;
- }
- if (verify_elf_header(header) < 0) {
- DL_ERR("not a valid ELF executable: %s", name);
- return NULL;
- }
-
- // Read the program header table.
- const Elf32_Phdr* phdr_table;
- phdr_ptr phdr_holder;
- ret = phdr_table_load(fd.fd, header->e_phoff, header->e_phnum,
- &phdr_holder.phdr_mmap, &phdr_holder.phdr_size, &phdr_table);
- if (ret < 0) {
- DL_ERR("can't load program header table: %s: %s", name, strerror(errno));
- return NULL;
- }
- size_t phdr_count = header->e_phnum;
-
- // Get the load extents.
- Elf32_Addr ext_sz = phdr_table_get_load_size(phdr_table, phdr_count);
- TRACE("[ '%s' wants sz=0x%08x ]\n", name, ext_sz);
- if (ext_sz == 0) {
- DL_ERR("no loadable segments in file: %s", name);
+ // Read the ELF header and load the segments.
+ ElfReader elf_reader(name, fd);
+ if (!elf_reader.Load()) {
return NULL;
}
- // We no longer support pre-linked libraries.
- if (is_prelinked(fd.fd, name)) {
- return NULL;
- }
-
- // Reserve address space for all loadable segments.
- void* load_start = NULL;
- Elf32_Addr load_size = 0;
- Elf32_Addr load_bias = 0;
- ret = phdr_table_reserve_memory(phdr_table,
- phdr_count,
- &load_start,
- &load_size,
- &load_bias);
- if (ret < 0) {
- DL_ERR("can't reserve %d bytes in address space for \"%s\": %s",
- ext_sz, name, strerror(errno));
- return NULL;
- }
-
- TRACE("[ allocated memory for %s @ %p (0x%08x) ]\n", name, load_start, load_size);
-
- /* Map all the segments in our address space with default protections */
- ret = phdr_table_load_segments(phdr_table,
- phdr_count,
- load_bias,
- fd.fd);
- if (ret < 0) {
- DL_ERR("can't map loadable segments for \"%s\": %s",
- name, strerror(errno));
- return NULL;
- }
-
- soinfo_ptr si(name);
- if (si.ptr == NULL) {
- return NULL;
- }
-
- si.ptr->base = (Elf32_Addr) load_start;
- si.ptr->size = load_size;
- si.ptr->load_bias = load_bias;
- si.ptr->flags = 0;
- si.ptr->entry = 0;
- si.ptr->dynamic = NULL;
- si.ptr->phnum = phdr_count;
- si.ptr->phdr = phdr_table_get_loaded_phdr(phdr_table, phdr_count, load_bias);
- if (si.ptr->phdr == NULL) {
- DL_ERR("can't find loaded PHDR for \"%s\"", name);
+ const char* bname = strrchr(name, '/');
+ soinfo* si = soinfo_alloc(bname ? bname + 1 : name);
+ if (si == NULL) {
return NULL;
}
-
- return si.release();
+ si->base = elf_reader.load_start();
+ si->size = elf_reader.load_size();
+ si->load_bias = elf_reader.load_bias();
+ si->flags = 0;
+ si->entry = 0;
+ si->dynamic = NULL;
+ si->phnum = elf_reader.phdr_count();
+ si->phdr = elf_reader.loaded_phdr();
+ return si;
}
static soinfo *find_loaded_library(const char *name)
@@ -1686,7 +1520,7 @@ static bool soinfo_link_image(soinfo* si) {
for (size_t i = 0; gLdPreloadNames[i] != NULL; i++) {
soinfo* lsi = find_library(gLdPreloadNames[i]);
if (lsi == NULL) {
- strlcpy(tmp_err_buf, linker_get_error(), sizeof(tmp_err_buf));
+ strlcpy(tmp_err_buf, linker_get_error_buffer(), sizeof(tmp_err_buf));
DL_ERR("could not load library \"%s\" needed by \"%s\"; caused by %s",
gLdPreloadNames[i], si->name, tmp_err_buf);
return false;
@@ -1704,7 +1538,7 @@ static bool soinfo_link_image(soinfo* si) {
DEBUG("%s needs %s\n", si->name, library_name);
soinfo* lsi = find_library(library_name);
if (lsi == NULL) {
- strlcpy(tmp_err_buf, linker_get_error(), sizeof(tmp_err_buf));
+ strlcpy(tmp_err_buf, linker_get_error_buffer(), sizeof(tmp_err_buf));
DL_ERR("could not load library \"%s\" needed by \"%s\"; caused by %s",
library_name, si->name, tmp_err_buf);
return false;
@@ -1804,7 +1638,7 @@ static unsigned __linker_init_post_relocation(KernelArgumentBlock& args, unsigne
// Get a few environment variables.
const char* LD_DEBUG = linker_env_get("LD_DEBUG");
if (LD_DEBUG != NULL) {
- debug_verbosity = atoi(LD_DEBUG);
+ gLdDebugVerbosity = atoi(LD_DEBUG);
}
// Normally, these are cleaned by linker_env_init, but the test
@@ -1890,9 +1724,7 @@ static unsigned __linker_init_post_relocation(KernelArgumentBlock& args, unsigne
somain = si;
if (!soinfo_link_image(si)) {
- const char* msg = "CANNOT LINK EXECUTABLE\n";
- write(2, __linker_dl_err_buf, strlen(__linker_dl_err_buf));
- write(2, msg, strlen(msg));
+ __libc_format_fd(2, "CANNOT LINK EXECUTABLE: %s\n", linker_get_error_buffer());
exit(EXIT_FAILURE);
}
diff --git a/linker/linker.h b/linker/linker.h
index dac555a..cef6905 100644
--- a/linker/linker.h
+++ b/linker/linker.h
@@ -36,6 +36,15 @@
#include <link.h>
+#include <private/debug_format.h>
+
+#define DL_ERR(fmt, x...) \
+ do { \
+ __libc_format_buffer(linker_get_error_buffer(), linker_get_error_buffer_size(), fmt, ##x); \
+ /* If LD_DEBUG is set high enough, log every dlerror(3) message. */ \
+ DEBUG("%s\n", linker_get_error_buffer()); \
+ } while(0)
+
// Returns the address of the page containing address 'x'.
#define PAGE_START(x) ((x) & PAGE_MASK)
@@ -169,7 +178,6 @@ int do_dlclose(soinfo* si);
Elf32_Sym* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* start);
soinfo* find_containing_library(const void* addr);
-const char* linker_get_error();
Elf32_Sym* dladdr_find_symbol(soinfo* si, const void* addr);
Elf32_Sym* dlsym_handle_lookup(soinfo* si, const char* name);
@@ -177,4 +185,7 @@ Elf32_Sym* dlsym_handle_lookup(soinfo* si, const char* name);
void debuggerd_init();
extern "C" void notify_gdb_of_libraries();
+char* linker_get_error_buffer();
+size_t linker_get_error_buffer_size();
+
#endif
diff --git a/linker/linker_debug.h b/linker/linker_debug.h
index b326d00..bf9ef92 100644
--- a/linker/linker_debug.h
+++ b/linker/linker_debug.h
@@ -54,15 +54,17 @@
#include <private/debug_format.h>
+__LIBC_HIDDEN__ extern int gLdDebugVerbosity;
+
#if LINKER_DEBUG_TO_LOG
#define _PRINTVF(v,x...) \
do { \
- if (debug_verbosity > (v)) __libc_format_log(5-(v),"linker",x); \
+ if (gLdDebugVerbosity > (v)) __libc_format_log(5-(v),"linker",x); \
} while (0)
#else /* !LINKER_DEBUG_TO_LOG */
#define _PRINTVF(v,x...) \
do { \
- if (debug_verbosity > (v)) __libc_format_fd(1, x); \
+ if (gLdDebugVerbosity > (v)) __libc_format_fd(1, x); \
} while (0)
#endif /* !LINKER_DEBUG_TO_LOG */
diff --git a/linker/linker_phdr.cpp b/linker/linker_phdr.cpp
index acd18cd..64dbb70 100644
--- a/linker/linker_phdr.cpp
+++ b/linker/linker_phdr.cpp
@@ -26,10 +26,13 @@
* SUCH DAMAGE.
*/
+#include "linker_phdr.h"
+
#include <errno.h>
#include <sys/mman.h>
-#include "linker_phdr.h"
+#include "linker.h"
+#include "linker_debug.h"
/**
TECHNICAL NOTE ON ELF LOADING.
@@ -112,66 +115,116 @@
MAYBE_MAP_FLAG((x), PF_R, PROT_READ) | \
MAYBE_MAP_FLAG((x), PF_W, PROT_WRITE))
-/* Load the program header table from an ELF file into a read-only private
- * anonymous mmap-ed block.
- *
- * Input:
- * fd -> file descriptor
- * phdr_offset -> file offset of phdr table
- * phdr_num -> number of entries in the table.
- *
- * Output:
- * phdr_mmap -> address of mmap block in memory.
- * phdr_memsize -> size of mmap block in memory.
- * phdr_table -> address of first entry in memory.
- *
- * Return:
- * -1 on error, or 0 on success.
- */
-int phdr_table_load(int fd,
- Elf32_Addr phdr_offset,
- Elf32_Half phdr_num,
- void** phdr_mmap,
- Elf32_Addr* phdr_size,
- const Elf32_Phdr** phdr_table)
-{
- Elf32_Addr page_min, page_max, page_offset;
- void* mmap_result;
-
- /* Just like the kernel, we only accept program header tables that
- * are smaller than 64KB. */
- if (phdr_num < 1 || phdr_num > 65536/sizeof(Elf32_Phdr)) {
- errno = EINVAL;
- return -1;
- }
-
- page_min = PAGE_START(phdr_offset);
- page_max = PAGE_END(phdr_offset + phdr_num*sizeof(Elf32_Phdr));
- page_offset = PAGE_OFFSET(phdr_offset);
-
- mmap_result = mmap(NULL,
- page_max - page_min,
- PROT_READ,
- MAP_PRIVATE,
- fd,
- page_min);
+ElfReader::ElfReader(const char* name, int fd)
+ : name_(name), fd_(fd),
+ phdr_num_(0), phdr_mmap_(NULL), phdr_table_(NULL), phdr_size_(0),
+ load_start_(NULL), load_size_(0), load_bias_(0),
+ loaded_phdr_(NULL) {
+}
- if (mmap_result == MAP_FAILED) {
- return -1;
- }
+ElfReader::~ElfReader() {
+ if (fd_ != -1) {
+ close(fd_);
+ }
+ if (phdr_mmap_ != NULL) {
+ munmap(phdr_mmap_, phdr_size_);
+ }
+}
- *phdr_mmap = mmap_result;
- *phdr_size = page_max - page_min;
- *phdr_table = (Elf32_Phdr*)((char*)mmap_result + page_offset);
+bool ElfReader::Load() {
+ return ReadElfHeader() &&
+ VerifyElfHeader() &&
+ ReadProgramHeader() &&
+ ReserveAddressSpace() &&
+ LoadSegments() &&
+ FindPhdr();
+}
- return 0;
+bool ElfReader::ReadElfHeader() {
+ ssize_t rc = TEMP_FAILURE_RETRY(read(fd_, &header_, sizeof(header_)));
+ if (rc < 0) {
+ DL_ERR("can't read file \"%s\": %s", name_, strerror(errno));
+ return false;
+ }
+ if (rc != sizeof(header_)) {
+ DL_ERR("\"%s\" is too small to be an ELF executable", name_);
+ return false;
+ }
+ return true;
}
-void phdr_table_unload(void* phdr_mmap, Elf32_Addr phdr_memsize)
-{
- munmap(phdr_mmap, phdr_memsize);
+bool ElfReader::VerifyElfHeader() {
+ if (header_.e_ident[EI_MAG0] != ELFMAG0 ||
+ header_.e_ident[EI_MAG1] != ELFMAG1 ||
+ header_.e_ident[EI_MAG2] != ELFMAG2 ||
+ header_.e_ident[EI_MAG3] != ELFMAG3) {
+ DL_ERR("\"%s\" has bad ELF magic", name_);
+ return false;
+ }
+
+ if (header_.e_ident[EI_CLASS] != ELFCLASS32) {
+ DL_ERR("\"%s\" not 32-bit: %d", name_, header_.e_ident[EI_CLASS]);
+ return false;
+ }
+ if (header_.e_ident[EI_DATA] != ELFDATA2LSB) {
+ DL_ERR("\"%s\" not little-endian: %d", name_, header_.e_ident[EI_DATA]);
+ return false;
+ }
+
+ if (header_.e_type != ET_DYN) {
+ DL_ERR("\"%s\" has unexpected e_type: %d", name_, header_.e_type);
+ return false;
+ }
+
+ if (header_.e_version != EV_CURRENT) {
+ DL_ERR("\"%s\" has unexpected e_version: %d", name_, header_.e_version);
+ return false;
+ }
+
+ if (header_.e_machine !=
+#ifdef ANDROID_ARM_LINKER
+ EM_ARM
+#elif defined(ANDROID_MIPS_LINKER)
+ EM_MIPS
+#elif defined(ANDROID_X86_LINKER)
+ EM_386
+#endif
+ ) {
+ DL_ERR("\"%s\" has unexpected e_machine: %d", name_, header_.e_machine);
+ return false;
+ }
+
+ return true;
}
+// Loads the program header table from an ELF file into a read-only private
+// anonymous mmap-ed block.
+bool ElfReader::ReadProgramHeader() {
+ phdr_num_ = header_.e_phnum;
+
+ // Like the kernel, we only accept program header tables that
+ // are smaller than 64KiB.
+ if (phdr_num_ < 1 || phdr_num_ > 65536/sizeof(Elf32_Phdr)) {
+ DL_ERR("\"%s\" has invalid e_phnum: %d", name_, phdr_num_);
+ return false;
+ }
+
+ Elf32_Addr page_min = PAGE_START(header_.e_phoff);
+ Elf32_Addr page_max = PAGE_END(header_.e_phoff + (phdr_num_ * sizeof(Elf32_Phdr)));
+ Elf32_Addr page_offset = PAGE_OFFSET(header_.e_phoff);
+
+ phdr_size_ = page_max - page_min;
+
+ void* mmap_result = mmap(NULL, phdr_size_, PROT_READ, MAP_PRIVATE, fd_, page_min);
+ if (mmap_result == MAP_FAILED) {
+ DL_ERR("\"%s\" phdr mmap failed: %s", name_, strerror(errno));
+ return false;
+ }
+
+ phdr_mmap_ = mmap_result;
+ phdr_table_ = reinterpret_cast<Elf32_Phdr*>(reinterpret_cast<char*>(mmap_result) + page_offset);
+ return true;
+}
/* Compute the extent of all loadable segments in an ELF program header
* table. This corresponds to the page-aligned size in bytes that needs to be
@@ -211,134 +264,100 @@ Elf32_Addr phdr_table_get_load_size(const Elf32_Phdr* phdr_table,
return max_vaddr - min_vaddr;
}
-/* Reserve a virtual address range big enough to hold all loadable
- * segments of a program header table. This is done by creating a
- * private anonymous mmap() with PROT_NONE.
- *
- * Input:
- * phdr_table -> program header table
- * phdr_count -> number of entries in the tables
- * Output:
- * load_start -> first page of reserved address space range
- * load_size -> size in bytes of reserved address space range
- * load_bias -> load bias, as described in technical note above.
- *
- * Return:
- * 0 on success, -1 otherwise. Error code in errno.
- */
-int
-phdr_table_reserve_memory(const Elf32_Phdr* phdr_table,
- size_t phdr_count,
- void** load_start,
- Elf32_Addr* load_size,
- Elf32_Addr* load_bias)
-{
- Elf32_Addr size = phdr_table_get_load_size(phdr_table, phdr_count);
- if (size == 0) {
- errno = EINVAL;
- return -1;
- }
-
- int mmap_flags = MAP_PRIVATE | MAP_ANONYMOUS;
- void* start = mmap(NULL, size, PROT_NONE, mmap_flags, -1, 0);
- if (start == MAP_FAILED) {
- return -1;
+// Reserve a virtual address range big enough to hold all loadable
+// segments of a program header table. This is done by creating a
+// private anonymous mmap() with PROT_NONE.
+bool ElfReader::ReserveAddressSpace() {
+ load_size_ = phdr_table_get_load_size(phdr_table_, phdr_num_);
+ if (load_size_ == 0) {
+ DL_ERR("\"%s\" has no loadable segments", name_);
+ return false;
+ }
+
+ int mmap_flags = MAP_PRIVATE | MAP_ANONYMOUS;
+ void* start = mmap(NULL, load_size_, PROT_NONE, mmap_flags, -1, 0);
+ if (start == MAP_FAILED) {
+ DL_ERR("couldn't reserve %d bytes of address space for \"%s\"", load_size_, name_);
+ return false;
+ }
+
+ load_start_ = start;
+ load_bias_ = 0;
+
+ for (size_t i = 0; i < phdr_num_; ++i) {
+ const Elf32_Phdr* phdr = &phdr_table_[i];
+ if (phdr->p_type == PT_LOAD) {
+ load_bias_ = reinterpret_cast<Elf32_Addr>(start) - PAGE_START(phdr->p_vaddr);
+ break;
}
-
- *load_start = start;
- *load_size = size;
- *load_bias = 0;
-
- for (size_t i = 0; i < phdr_count; ++i) {
- const Elf32_Phdr* phdr = &phdr_table[i];
- if (phdr->p_type == PT_LOAD) {
- *load_bias = (Elf32_Addr)start - PAGE_START(phdr->p_vaddr);
- break;
- }
- }
- return 0;
+ }
+ return true;
}
-/* Map all loadable segments in process' address space.
- * This assumes you already called phdr_table_reserve_memory to
- * reserve the address space range for the library.
- *
- * Input:
- * phdr_table -> program header table
- * phdr_count -> number of entries in the table
- * load_bias -> load offset.
- * fd -> input file descriptor.
- *
- * Return:
- * 0 on success, -1 otherwise. Error code in errno.
- */
-int
-phdr_table_load_segments(const Elf32_Phdr* phdr_table,
- int phdr_count,
- Elf32_Addr load_bias,
- int fd)
-{
- int nn;
+// Map all loadable segments in process' address space.
+// This assumes you already called phdr_table_reserve_memory to
+// reserve the address space range for the library.
+// TODO: assert assumption.
+bool ElfReader::LoadSegments() {
+ for (size_t i = 0; i < phdr_num_; ++i) {
+ const Elf32_Phdr* phdr = &phdr_table_[i];
- for (nn = 0; nn < phdr_count; nn++) {
- const Elf32_Phdr* phdr = &phdr_table[nn];
- void* seg_addr;
-
- if (phdr->p_type != PT_LOAD)
- continue;
-
- /* Segment addresses in memory */
- Elf32_Addr seg_start = phdr->p_vaddr + load_bias;
- Elf32_Addr seg_end = seg_start + phdr->p_memsz;
+ if (phdr->p_type != PT_LOAD) {
+ continue;
+ }
- Elf32_Addr seg_page_start = PAGE_START(seg_start);
- Elf32_Addr seg_page_end = PAGE_END(seg_end);
+ // Segment addresses in memory.
+ Elf32_Addr seg_start = phdr->p_vaddr + load_bias_;
+ Elf32_Addr seg_end = seg_start + phdr->p_memsz;
- Elf32_Addr seg_file_end = seg_start + phdr->p_filesz;
+ Elf32_Addr seg_page_start = PAGE_START(seg_start);
+ Elf32_Addr seg_page_end = PAGE_END(seg_end);
- /* File offsets */
- Elf32_Addr file_start = phdr->p_offset;
- Elf32_Addr file_end = file_start + phdr->p_filesz;
+ Elf32_Addr seg_file_end = seg_start + phdr->p_filesz;
- Elf32_Addr file_page_start = PAGE_START(file_start);
+ // File offsets.
+ Elf32_Addr file_start = phdr->p_offset;
+ Elf32_Addr file_end = file_start + phdr->p_filesz;
- seg_addr = mmap((void*)seg_page_start,
- file_end - file_page_start,
- PFLAGS_TO_PROT(phdr->p_flags),
- MAP_FIXED|MAP_PRIVATE,
- fd,
- file_page_start);
+ Elf32_Addr file_page_start = PAGE_START(file_start);
- if (seg_addr == MAP_FAILED) {
- return -1;
- }
-
- /* if the segment is writable, and does not end on a page boundary,
- * zero-fill it until the page limit. */
- if ((phdr->p_flags & PF_W) != 0 && PAGE_OFFSET(seg_file_end) > 0) {
- memset((void*)seg_file_end, 0, PAGE_SIZE - PAGE_OFFSET(seg_file_end));
- }
+ void* seg_addr = mmap((void*)seg_page_start,
+ file_end - file_page_start,
+ PFLAGS_TO_PROT(phdr->p_flags),
+ MAP_FIXED|MAP_PRIVATE,
+ fd_,
+ file_page_start);
+ if (seg_addr == MAP_FAILED) {
+ DL_ERR("couldn't map \"%s\" segment %d: %s", name_, i, strerror(errno));
+ return false;
+ }
- seg_file_end = PAGE_END(seg_file_end);
+ // if the segment is writable, and does not end on a page boundary,
+ // zero-fill it until the page limit.
+ if ((phdr->p_flags & PF_W) != 0 && PAGE_OFFSET(seg_file_end) > 0) {
+ memset((void*)seg_file_end, 0, PAGE_SIZE - PAGE_OFFSET(seg_file_end));
+ }
- /* seg_file_end is now the first page address after the file
- * content. If seg_end is larger, we need to zero anything
- * between them. This is done by using a private anonymous
- * map for all extra pages.
- */
- if (seg_page_end > seg_file_end) {
- void* zeromap = mmap((void*)seg_file_end,
- seg_page_end - seg_file_end,
- PFLAGS_TO_PROT(phdr->p_flags),
- MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE,
- -1,
- 0);
- if (zeromap == MAP_FAILED) {
- return -1;
- }
- }
+ seg_file_end = PAGE_END(seg_file_end);
+
+ // seg_file_end is now the first page address after the file
+ // content. If seg_end is larger, we need to zero anything
+ // between them. This is done by using a private anonymous
+ // map for all extra pages.
+ if (seg_page_end > seg_file_end) {
+ void* zeromap = mmap((void*)seg_file_end,
+ seg_page_end - seg_file_end,
+ PFLAGS_TO_PROT(phdr->p_flags),
+ MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE,
+ -1,
+ 0);
+ if (zeromap == MAP_FAILED) {
+ DL_ERR("couldn't zero fill \"%s\" gap: %s", name_, strerror(errno));
+ return false;
+ }
}
- return 0;
+ }
+ return true;
}
/* Used internally. Used to set the protection bits of all loaded segments
@@ -577,72 +596,55 @@ phdr_table_get_dynamic_section(const Elf32_Phdr* phdr_table,
}
}
-/* Return the address of the program header table as it appears in the loaded
- * segments in memory. This is in contrast with the input 'phdr_table' which
- * is temporary and will be released before the library is relocated.
- *
- * Input:
- * phdr_table -> program header table
- * phdr_count -> number of entries in tables
- * load_bias -> load bias
- * Return:
- * Address of loaded program header table on success (it has
- * 'phdr_count' entries), or NULL on failure (no error code).
- */
-const Elf32_Phdr*
-phdr_table_get_loaded_phdr(const Elf32_Phdr* phdr_table,
- int phdr_count,
- Elf32_Addr load_bias)
-{
- const Elf32_Phdr* phdr = phdr_table;
- const Elf32_Phdr* phdr_limit = phdr + phdr_count;
- Elf32_Addr loaded = 0;
- Elf32_Addr loaded_end;
+// Returns the address of the program header table as it appears in the loaded
+// segments in memory. This is in contrast with 'phdr_table_' which
+// is temporary and will be released before the library is relocated.
+bool ElfReader::FindPhdr() {
+ const Elf32_Phdr* phdr_limit = phdr_table_ + phdr_num_;
- /* If there is a PT_PHDR, use it directly */
- for (phdr = phdr_table; phdr < phdr_limit; phdr++) {
- if (phdr->p_type == PT_PHDR) {
- loaded = load_bias + phdr->p_vaddr;
- goto CHECK;
- }
+ // If there is a PT_PHDR, use it directly.
+ for (const Elf32_Phdr* phdr = phdr_table_; phdr < phdr_limit; ++phdr) {
+ if (phdr->p_type == PT_PHDR) {
+ return CheckPhdr(load_bias_ + phdr->p_vaddr);
}
-
- /* Otherwise, check the first loadable segment. If its file offset
- * is 0, it starts with the ELF header, and we can trivially find the
- * loaded program header from it. */
- for (phdr = phdr_table; phdr < phdr_limit; phdr++) {
- if (phdr->p_type == PT_LOAD) {
- if (phdr->p_offset == 0) {
- Elf32_Addr elf_addr = load_bias + phdr->p_vaddr;
- const Elf32_Ehdr* ehdr = (const Elf32_Ehdr*)(void*)elf_addr;
- Elf32_Addr offset = ehdr->e_phoff;
- loaded = (Elf32_Addr)ehdr + offset;
- goto CHECK;
- }
- break;
- }
+ }
+
+ // Otherwise, check the first loadable segment. If its file offset
+ // is 0, it starts with the ELF header, and we can trivially find the
+ // loaded program header from it.
+ for (const Elf32_Phdr* phdr = phdr_table_; phdr < phdr_limit; ++phdr) {
+ if (phdr->p_type == PT_LOAD) {
+ if (phdr->p_offset == 0) {
+ Elf32_Addr elf_addr = load_bias_ + phdr->p_vaddr;
+ const Elf32_Ehdr* ehdr = (const Elf32_Ehdr*)(void*)elf_addr;
+ Elf32_Addr offset = ehdr->e_phoff;
+ return CheckPhdr((Elf32_Addr)ehdr + offset);
+ }
+ break;
}
+ }
- /* We didn't find it, let the client know. He may be able to
- * keep a copy of the input phdr_table instead. */
- return NULL;
-
-CHECK:
- /* Ensure that our program header is actually within a loadable
- * segment. This should help catch badly-formed ELF files that
- * would cause the linker to crash later when trying to access it.
- */
- loaded_end = loaded + phdr_count*sizeof(Elf32_Phdr);
-
- for (phdr = phdr_table; phdr < phdr_limit; phdr++) {
- if (phdr->p_type != PT_LOAD)
- continue;
- Elf32_Addr seg_start = phdr->p_vaddr + load_bias;
- Elf32_Addr seg_end = phdr->p_filesz + seg_start;
+ DL_ERR("can't find loaded phdr for \"%s\"", name_);
+ return false;
+}
- if (seg_start <= loaded && loaded_end <= seg_end) {
- return (const Elf32_Phdr*)loaded;
- }
+// Ensures that our program header is actually within a loadable
+// segment. This should help catch badly-formed ELF files that
+// would cause the linker to crash later when trying to access it.
+bool ElfReader::CheckPhdr(Elf32_Addr loaded) {
+ const Elf32_Phdr* phdr_limit = phdr_table_ + phdr_num_;
+ Elf32_Addr loaded_end = loaded + (phdr_num_ * sizeof(Elf32_Phdr));
+ for (Elf32_Phdr* phdr = phdr_table_; phdr < phdr_limit; ++phdr) {
+ if (phdr->p_type != PT_LOAD) {
+ continue;
+ }
+ Elf32_Addr seg_start = phdr->p_vaddr + load_bias_;
+ Elf32_Addr seg_end = phdr->p_filesz + seg_start;
+ if (seg_start <= loaded && loaded_end <= seg_end) {
+ loaded_phdr_ = reinterpret_cast<const Elf32_Phdr*>(loaded);
+ return true;
}
- return NULL;
+ }
+ DL_ERR("\"%s\" loaded phdr %x not in loadable segment", name_, loaded);
+ return false;
}
diff --git a/linker/linker_phdr.h b/linker/linker_phdr.h
index ec55159..a31d1d9 100644
--- a/linker/linker_phdr.h
+++ b/linker/linker_phdr.h
@@ -37,33 +37,50 @@
#include "linker.h"
-int
-phdr_table_load(int fd,
- Elf32_Addr phdr_offset,
- Elf32_Half phdr_num,
- void** phdr_mmap,
- Elf32_Addr* phdr_size,
- const Elf32_Phdr** phdr_table);
+class ElfReader {
+ public:
+ ElfReader(const char* name, int fd);
+ ~ElfReader();
-void
-phdr_table_unload(void* phdr_mmap, Elf32_Addr phdr_memsize);
+ bool Load();
-Elf32_Addr
-phdr_table_get_load_size(const Elf32_Phdr* phdr_table,
- size_t phdr_count);
+ size_t phdr_count() { return phdr_num_; }
+ Elf32_Addr load_start() { return reinterpret_cast<Elf32_Addr>(load_start_); }
+ Elf32_Addr load_size() { return load_size_; }
+ Elf32_Addr load_bias() { return load_bias_; }
+ const Elf32_Phdr* loaded_phdr() { return loaded_phdr_; }
-int
-phdr_table_reserve_memory(const Elf32_Phdr* phdr_table,
- size_t phdr_count,
- void** load_start,
- Elf32_Addr* load_size,
- Elf32_Addr* load_bias);
+ private:
+ bool ReadElfHeader();
+ bool VerifyElfHeader();
+ bool ReadProgramHeader();
+ bool ReserveAddressSpace();
+ bool LoadSegments();
+ bool FindPhdr();
+ bool CheckPhdr(Elf32_Addr);
-int
-phdr_table_load_segments(const Elf32_Phdr* phdr_table,
- int phdr_count,
- Elf32_Addr load_bias,
- int fd);
+ const char* name_;
+ int fd_;
+
+ Elf32_Ehdr header_;
+ size_t phdr_num_;
+
+ void* phdr_mmap_;
+ Elf32_Phdr* phdr_table_;
+ Elf32_Addr phdr_size_;
+
+ // First page of reserved address space.
+ void* load_start_;
+ // Size in bytes of reserved address space.
+ Elf32_Addr load_size_;
+ // Load bias.
+ Elf32_Addr load_bias_;
+
+ // Loaded phdr.
+ const Elf32_Phdr* loaded_phdr_;
+};
+
+Elf32_Addr phdr_table_get_load_size(const Elf32_Phdr* phdr, size_t phnum);
int
phdr_table_protect_segments(const Elf32_Phdr* phdr_table,
@@ -80,10 +97,6 @@ phdr_table_protect_gnu_relro(const Elf32_Phdr* phdr_table,
int phdr_count,
Elf32_Addr load_bias);
-const Elf32_Phdr*
-phdr_table_get_loaded_phdr(const Elf32_Phdr* phdr_table,
- int phdr_count,
- Elf32_Addr load_bias);
#ifdef ANDROID_ARM_LINKER
int
generated by cgit v1.1 at 2024-11-15 11:19:15 +0000