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vdso.c: share the PIE part of the vDSO proxy machinery between all architectures

Browse source 
This patch splits the file arch/x86/vdso-pie.c into machine-dependent
and machine-independent parts by moving the routines vdso_fill_symtable(),
vdso_proxify(), and vdso_remap() to the file pie/vdso.c.

The ARM version of the routines is moved to the source pie/vdso-stub.c
to provide the vDSO proxy stub implementation for architectures
that don't provide the vDSO.

Signed-off-by: Alexander Kartashov <alekskartashov@parallels.com>
Looks-good-to: Cyrill Gorcunov <gorcunov@openvz.org>
Reviewed-by: Christopher Covington <cov@codeaurora.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
This commit is contained in:
Alexander Kartashov 2014-03-18 21:14:15 +04:00 • committed by Pavel Emelyanov
parent 3ce2f87871
commit 7535c3909a
9 changed files with 296 additions and 259 deletions
Download patch file Download diff file Expand all files Collapse all files

4
Makefile
View file

@ -180,6 +180,10 @@ PROGRAM-BUILTINS += built-in.o
$(ARCH_DIR)/vdso-pie.o: pie
$(Q) $(MAKE) $(build)=pie $(ARCH_DIR)/vdso-pie.o
PROGRAM-BUILTINS += $(ARCH_DIR)/vdso-pie.o
pie/$(VDSO_O): pie
$(Q) $(MAKE) $(build)=pie pie/$(VDSO_O)
PROGRAM-BUILTINS += pie/$(VDSO_O)
$(PROGRAM): $(SYSCALL-LIB) $(ARCH-LIB) $(PROGRAM-BUILTINS)
$(E) " LINK " $@

3
arch/arm/include/asm/vdso.h
View file

@ -12,9 +12,6 @@ struct vm_area_list;
#define VDSO_SYMBOL_MAX 1
extern int vdso_redirect_calls(void *base_to, void *base_from, struct vdso_symtable *to, struct vdso_symtable *from);
extern int vdso_fill_symtable(char *mem, size_t size,struct vdso_symtable *t);
extern int vdso_remap(char *who, unsigned long from, unsigned long to, size_t size);
extern int vdso_proxify(char *who, struct vdso_symtable *sym_rt, VmaEntry *vma_entry, unsigned long vdso_rt_parked_at);
extern int parasite_fixup_vdso(struct parasite_ctl *ctl, pid_t pid,
struct vm_area_list *vma_area_list);

15
arch/arm/vdso-pie.c
View file

@ -15,18 +15,3 @@ int vdso_redirect_calls(void *base_to, void *base_from,
{
return 0;
}
int vdso_fill_symtable(char *mem, size_t size, struct vdso_symtable *t)
{
return 0;
}
int vdso_remap(char *who, unsigned long from, unsigned long to, size_t size)
{
return 0;
}
int vdso_proxify(char *who, struct vdso_symtable *sym_rt, VmaEntry *vma, unsigned long vdso_rt_parked_at)
{
return 0;
}

3
arch/x86/include/asm/vdso.h
View file

@ -45,9 +45,6 @@ struct parasite_ctl;
struct vm_area_list;
extern int vdso_redirect_calls(void *base_to, void *base_from, struct vdso_symtable *to, struct vdso_symtable *from);
extern int vdso_fill_symtable(char *mem, size_t size,struct vdso_symtable *t);
extern int vdso_remap(char *who, unsigned long from, unsigned long to, size_t size);
extern int vdso_proxify(char *who, struct vdso_symtable *sym_rt, VmaEntry *vma_entry, unsigned long vdso_rt_parked_at);
extern int parasite_fixup_vdso(struct parasite_ctl *ctl, pid_t pid,
struct vm_area_list *vma_area_list);

237
arch/x86/vdso-pie.c
View file

@ -56,240 +56,3 @@ int vdso_redirect_calls(void *base_to, void *base_from,
return 0;
}
static unsigned int get_symbol_index(char *symbol, char *symbols[], size_t size)
{
unsigned int i;
for (i = 0; symbol && i < size; i++) {
if (!builtin_strcmp(symbol, symbols[i]))
return i;
}
return VDSO_SYMBOL_MAX;
}
/* Check if pointer is out-of-bound */
static bool __ptr_oob(void *ptr, void *start, size_t size)
{
void *end = (void *)((unsigned long)start + size);
return ptr > end || ptr < start;
}
int vdso_fill_symtable(char *mem, size_t size, struct vdso_symtable *t)
{
Elf64_Ehdr *ehdr = (void *)mem;
Elf64_Shdr *shdr, *shdr_strtab;
Elf64_Shdr *shdr_dynsym;
Elf64_Shdr *shdr_dynstr;
Elf64_Phdr *phdr;
Elf64_Shdr *text;
Elf64_Sym *sym;
char *section_names, *dynsymbol_names;
unsigned long base = VDSO_BAD_ADDR;
unsigned int i, j, k;
DECLARE_VDSO(vdso_ident, vdso_symbols);
BUILD_BUG_ON(sizeof(vdso_ident) != sizeof(ehdr->e_ident));
pr_debug("Parsing at %lx %lx\n",
(long)mem, (long)mem + (long)size);
/*
* Make sure it's a file we support.
*/
if (builtin_memcmp(ehdr->e_ident, vdso_ident, sizeof(vdso_ident))) {
pr_debug("Elf header magic mismatch\n");
goto err;
}
/*
* Figure out base virtual address.
*/
phdr = (void *)&mem[ehdr->e_phoff];
for (i = 0; i < ehdr->e_phnum; i++, phdr++) {
if (__ptr_oob(phdr, mem, size))
goto err;
if (phdr->p_type == PT_LOAD) {
base = phdr->p_vaddr;
break;
}
}
if (base != VDSO_BAD_ADDR) {
pr_debug("Base address %lx\n", base);
} else {
pr_debug("No base address found\n");
goto err;
}
/*
* Where the section names lays.
*/
if (ehdr->e_shstrndx == SHN_UNDEF) {
pr_err("Section names are not found\n");
goto err;
}
shdr = (void *)&mem[ehdr->e_shoff];
shdr_strtab = &shdr[ehdr->e_shstrndx];
if (__ptr_oob(shdr_strtab, mem, size))
goto err;
section_names = (void *)&mem[shdr_strtab->sh_offset];
shdr_dynsym = shdr_dynstr = text = NULL;
for (i = 0; i < ehdr->e_shnum; i++, shdr++) {
if (__ptr_oob(shdr, mem, size))
goto err;
if (__ptr_oob(&section_names[shdr->sh_name], mem, size))
goto err;
#if 0
pr_debug("section: %2d -> %s\n",
i, &section_names[shdr->sh_name]);
#endif
if (shdr->sh_type == SHT_DYNSYM &&
builtin_strcmp(&section_names[shdr->sh_name],
".dynsym") == 0) {
shdr_dynsym = shdr;
} else if (shdr->sh_type == SHT_STRTAB &&
builtin_strcmp(&section_names[shdr->sh_name],
".dynstr") == 0) {
shdr_dynstr = shdr;
} else if (shdr->sh_type == SHT_PROGBITS &&
builtin_strcmp(&section_names[shdr->sh_name],
".text") == 0) {
text = shdr;
}
}
if (!shdr_dynsym || !shdr_dynstr || !text) {
pr_debug("No required sections found\n");
goto err;
}
dynsymbol_names = (void *)&mem[shdr_dynstr->sh_offset];
if (__ptr_oob(dynsymbol_names, mem, size) ||
__ptr_oob(shdr_dynsym, mem, size) ||
__ptr_oob(text, mem, size))
goto err;
/*
* Walk over global symbols and choose ones we need.
*/
j = shdr_dynsym->sh_size / sizeof(*sym);
sym = (void *)&mem[shdr_dynsym->sh_offset];
for (i = 0; i < j; i++, sym++) {
if (__ptr_oob(sym, mem, size))
goto err;
if (ELF64_ST_BIND(sym->st_info) != STB_GLOBAL ||
ELF64_ST_TYPE(sym->st_info) != STT_FUNC)
continue;
if (__ptr_oob(&dynsymbol_names[sym->st_name], mem, size))
goto err;
k = get_symbol_index(&dynsymbol_names[sym->st_name],
vdso_symbols,
ARRAY_SIZE(vdso_symbols));
if (k != VDSO_SYMBOL_MAX) {
builtin_memcpy(t->symbols[k].name, vdso_symbols[k],
sizeof(t->symbols[k].name));
t->symbols[k].offset = (unsigned long)sym->st_value - base;
#if 0
pr_debug("symbol: %#-16lx %2d %s\n",
t->symbols[k].offset, sym->st_shndx, t->symbols[k].name);
#endif
}
}
return 0;
err:
return -1;
}
int vdso_remap(char *who, unsigned long from, unsigned long to, size_t size)
{
unsigned long addr;
pr_debug("Remap %s %lx -> %lx\n", who, from, to);
addr = sys_mremap(from, size, size, MREMAP_MAYMOVE | MREMAP_FIXED, to);
if (addr != to) {
pr_err("Unable to remap %lx -> %lx %lx\n",
from, to, addr);
return -1;
}
return 0;
}
int vdso_proxify(char *who, struct vdso_symtable *sym_rt, VmaEntry *vma, unsigned long vdso_rt_parked_at)
{
struct vdso_symtable s = VDSO_SYMTABLE_INIT;
size_t size = vma_entry_len(vma);
bool remap_rt = true;
/*
* Find symbols in dumpee vdso.
*/
if (vdso_fill_symtable((void *)vma->start, size, &s))
return -1;
if (size == vdso_vma_size(sym_rt)) {
int i;
for (i = 0; i < ARRAY_SIZE(s.symbols); i++) {
if (s.symbols[i].offset != sym_rt->symbols[i].offset) {
remap_rt = false;
break;
}
}
} else
remap_rt = false;
/*
* Easy case -- the vdso from image has same offsets and size
* as runtime, so we simply remap runtime vdso to dumpee position
* without generating any proxy.
*/
if (remap_rt) {
pr_info("Runtime vdso matches dumpee, remap inplace\n");
if (sys_munmap((void *)vma->start, size)) {
pr_err("Failed to unmap %s\n", who);
return -1;
}
return vdso_remap(who, vdso_rt_parked_at, vma->start, size);
}
/*
* Now complex case -- we need to proxify calls. We redirect
* calls from dumpee vdso to runtime vdso, making dumpee
* to operate as proxy vdso.
*/
pr_info("Runtime vdso mismatches dumpee, generate proxy\n");
if (vdso_redirect_calls((void *)vdso_rt_parked_at,
(void *)vma->start,
sym_rt, &s)) {
pr_err("Failed to proxify dumpee contents\n");
return -1;
}
/*
* Put a special mark into runtime vdso, thus at next checkpoint
* routine we could detect this vdso and do not dump it, since
* it's auto-generated every new session if proxy required.
*/
sys_mprotect((void *)vdso_rt_parked_at, vdso_vma_size(sym_rt), PROT_WRITE);
vdso_put_mark((void *)vdso_rt_parked_at, vma->start);
sys_mprotect((void *)vdso_rt_parked_at, vdso_vma_size(sym_rt), VDSO_PROT);
return 0;
}

3
include/vdso.h
View file

@ -93,5 +93,8 @@ static inline void vdso_put_mark(void *where, unsigned long proxy_addr)
extern struct vdso_symtable vdso_sym_rt;
extern u64 vdso_pfn;
extern int vdso_init(void);
extern int vdso_remap(char *who, unsigned long from, unsigned long to, size_t size);
extern int vdso_fill_symtable(char *mem, size_t size, struct vdso_symtable *t);
extern int vdso_proxify(char *who, struct vdso_symtable *sym_rt, VmaEntry *vma_entry, unsigned long vdso_rt_parked_at);
#endif /* __CR_VDSO_H__ */

4
pie/Makefile
View file

@ -4,6 +4,9 @@ targets += restorer
obj-y += log-simple.o
obj-y += util.o
obj-y += util-fd.o
obj-y += $(VDSO_O)
obj-e += $(ARCH_DIR)/vdso-pie.o
parasite-obj-y += parasite.o
parasite-asm-e += $(ARCH_DIR)/parasite-head.o
@ -11,7 +14,6 @@ parasite-libs-e += $(SYSCALL-LIB)
restorer-obj-y += restorer.o
restorer-obj-e += $(ARCH_DIR)/restorer.o
restorer-obj-e += $(ARCH_DIR)/vdso-pie.o
restorer-libs-e += $(SYSCALL-LIB)
#

31
pie/vdso-stub.c Normal file
View file

@ -0,0 +1,31 @@
#include <elf.h>
#include <sys/mman.h>
#include "compiler.h"
#include "vdso.h"
#include "syscall.h"
#include "log.h"
#include "asm/string.h"
#ifdef LOG_PREFIX
# undef LOG_PREFIX
#endif
#define LOG_PREFIX "vdso: "
int vdso_remap(char *who, unsigned long from, unsigned long to, size_t size)
{
return 0;
}
int vdso_fill_symtable(char *mem, size_t size, struct vdso_symtable *t)
{
return 0;
}
int vdso_proxify(char *who, struct vdso_symtable *sym_rt, VmaEntry *vma, unsigned long vdso_rt_parked_at)
{
return 0;
}

255
pie/vdso.c Normal file
View file

@ -0,0 +1,255 @@
#include <elf.h>
#include <sys/mman.h>
#include "compiler.h"
#include "vdso.h"
#include "syscall.h"
#include "log.h"
#include "vma.h"
#include "asm/string.h"
#ifdef LOG_PREFIX
# undef LOG_PREFIX
#endif
#define LOG_PREFIX "vdso: "
static unsigned int get_symbol_index(char *symbol, char *symbols[], size_t size)
{
unsigned int i;
for (i = 0; symbol && i < size; i++) {
if (!builtin_strcmp(symbol, symbols[i]))
return i;
}
return VDSO_SYMBOL_MAX;
}
/* Check if pointer is out-of-bound */
static bool __ptr_oob(void *ptr, void *start, size_t size)
{
void *end = (void *)((unsigned long)start + size);
return ptr > end || ptr < start;
}
int vdso_fill_symtable(char *mem, size_t size, struct vdso_symtable *t)
{
Elf64_Ehdr *ehdr = (void *)mem;
Elf64_Shdr *shdr, *shdr_strtab;
Elf64_Shdr *shdr_dynsym;
Elf64_Shdr *shdr_dynstr;
Elf64_Phdr *phdr;
Elf64_Shdr *text;
Elf64_Sym *sym;
char *section_names, *dynsymbol_names;
unsigned long base = VDSO_BAD_ADDR;
unsigned int i, j, k;
DECLARE_VDSO(vdso_ident, vdso_symbols);
BUILD_BUG_ON(sizeof(vdso_ident) != sizeof(ehdr->e_ident));
pr_debug("Parsing at %lx %lx\n",
(long)mem, (long)mem + (long)size);
/*
* Make sure it's a file we support.
*/
if (builtin_memcmp(ehdr->e_ident, vdso_ident, sizeof(vdso_ident))) {
pr_debug("Elf header magic mismatch\n");
goto err;
}
/*
* Figure out base virtual address.
*/
phdr = (void *)&mem[ehdr->e_phoff];
for (i = 0; i < ehdr->e_phnum; i++, phdr++) {
if (__ptr_oob(phdr, mem, size))
goto err;
if (phdr->p_type == PT_LOAD) {
base = phdr->p_vaddr;
break;
}
}
if (base != VDSO_BAD_ADDR) {
pr_debug("Base address %lx\n", base);
} else {
pr_debug("No base address found\n");
goto err;
}
/*
* Where the section names lays.
*/
if (ehdr->e_shstrndx == SHN_UNDEF) {
pr_err("Section names are not found\n");
goto err;
}
shdr = (void *)&mem[ehdr->e_shoff];
shdr_strtab = &shdr[ehdr->e_shstrndx];
if (__ptr_oob(shdr_strtab, mem, size))
goto err;
section_names = (void *)&mem[shdr_strtab->sh_offset];
shdr_dynsym = shdr_dynstr = text = NULL;
for (i = 0; i < ehdr->e_shnum; i++, shdr++) {
if (__ptr_oob(shdr, mem, size))
goto err;
if (__ptr_oob(&section_names[shdr->sh_name], mem, size))
goto err;
#if 0
pr_debug("section: %2d -> %s\n",
i, &section_names[shdr->sh_name]);
#endif
if (shdr->sh_type == SHT_DYNSYM &&
builtin_strcmp(&section_names[shdr->sh_name],
".dynsym") == 0) {
shdr_dynsym = shdr;
} else if (shdr->sh_type == SHT_STRTAB &&
builtin_strcmp(&section_names[shdr->sh_name],
".dynstr") == 0) {
shdr_dynstr = shdr;
} else if (shdr->sh_type == SHT_PROGBITS &&
builtin_strcmp(&section_names[shdr->sh_name],
".text") == 0) {
text = shdr;
}
}
if (!shdr_dynsym || !shdr_dynstr || !text) {
pr_debug("No required sections found\n");
goto err;
}
dynsymbol_names = (void *)&mem[shdr_dynstr->sh_offset];
if (__ptr_oob(dynsymbol_names, mem, size) ||
__ptr_oob(shdr_dynsym, mem, size) ||
__ptr_oob(text, mem, size))
goto err;
/*
* Walk over global symbols and choose ones we need.
*/
j = shdr_dynsym->sh_size / sizeof(*sym);
sym = (void *)&mem[shdr_dynsym->sh_offset];
for (i = 0; i < j; i++, sym++) {
if (__ptr_oob(sym, mem, size))
goto err;
if (ELF64_ST_BIND(sym->st_info) != STB_GLOBAL ||
ELF64_ST_TYPE(sym->st_info) != STT_FUNC)
continue;
if (__ptr_oob(&dynsymbol_names[sym->st_name], mem, size))
goto err;
k = get_symbol_index(&dynsymbol_names[sym->st_name],
vdso_symbols,
ARRAY_SIZE(vdso_symbols));
if (k != VDSO_SYMBOL_MAX) {
builtin_memcpy(t->symbols[k].name, vdso_symbols[k],
sizeof(t->symbols[k].name));
t->symbols[k].offset = (unsigned long)sym->st_value - base;
#if 0
pr_debug("symbol: %#-16lx %2d %s\n",
t->symbols[k].offset, sym->st_shndx, t->symbols[k].name);
#endif
}
}
return 0;
err:
return -1;
}
int vdso_remap(char *who, unsigned long from, unsigned long to, size_t size)
{
unsigned long addr;
pr_debug("Remap %s %lx -> %lx\n", who, from, to);
addr = sys_mremap(from, size, size, MREMAP_MAYMOVE | MREMAP_FIXED, to);
if (addr != to) {
pr_err("Unable to remap %lx -> %lx %lx\n",
from, to, addr);
return -1;
}
return 0;
}
int vdso_proxify(char *who, struct vdso_symtable *sym_rt, VmaEntry *vma, unsigned long vdso_rt_parked_at)
{
struct vdso_symtable s = VDSO_SYMTABLE_INIT;
size_t size = vma_entry_len(vma);
bool remap_rt = true;
/*
* Find symbols in dumpee vdso.
*/
if (vdso_fill_symtable((void *)vma->start, size, &s))
return -1;
if (size == vdso_vma_size(sym_rt)) {
int i;
for (i = 0; i < ARRAY_SIZE(s.symbols); i++) {
if (s.symbols[i].offset != sym_rt->symbols[i].offset) {
remap_rt = false;
break;
}
}
} else
remap_rt = false;
/*
* Easy case -- the vdso from image has same offsets and size
* as runtime, so we simply remap runtime vdso to dumpee position
* without generating any proxy.
*/
if (remap_rt) {
pr_info("Runtime vdso matches dumpee, remap inplace\n");
if (sys_munmap((void *)vma->start, size)) {
pr_err("Failed to unmap %s\n", who);
return -1;
}
return vdso_remap(who, vdso_rt_parked_at, vma->start, size);
}
/*
* Now complex case -- we need to proxify calls. We redirect
* calls from dumpee vdso to runtime vdso, making dumpee
* to operate as proxy vdso.
*/
pr_info("Runtime vdso mismatches dumpee, generate proxy\n");
if (vdso_redirect_calls((void *)vdso_rt_parked_at,
(void *)vma->start,
sym_rt, &s)) {
pr_err("Failed to proxify dumpee contents\n");
return -1;
}
/*
* Put a special mark into runtime vdso, thus at next checkpoint
* routine we could detect this vdso and do not dump it, since
* it's auto-generated every new session if proxy required.
*/
sys_mprotect((void *)vdso_rt_parked_at, vdso_vma_size(sym_rt), PROT_WRITE);
vdso_put_mark((void *)vdso_rt_parked_at, vma->start);
sys_mprotect((void *)vdso_rt_parked_at, vdso_vma_size(sym_rt), VDSO_PROT);
return 0;
}