summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorJari Vetoniemi <mailroxas@gmail.com>2018-11-22 10:11:01 +0200
committerJari Vetoniemi <mailroxas@gmail.com>2018-11-22 10:11:01 +0200
commitdc55b81456e408850a44f8368819d41d50cc02d8 (patch)
tree82a12bf8ad041466be6e13fef90ccf94ae6d1f2b
parent832cf437dffdac83353b434433274fec21461f8d (diff)
refactor trampoline to use relative jmp/call
-rw-r--r--src/wrapper/wrapper.c33
1 files changed, 25 insertions, 8 deletions
diff --git a/src/wrapper/wrapper.c b/src/wrapper/wrapper.c
index 5b319f3..8ce6ffb 100644
--- a/src/wrapper/wrapper.c
+++ b/src/wrapper/wrapper.c
@@ -34,9 +34,12 @@ verbose_log(const char *fmt, ...)
# ifdef ANDROID_X86_LINKER
__asm__(
"wrapper_start: nop\n"
- "wrapper_symbol: pushl $0xFAFBFCFD\n"
- "wrapper_trace: movl $0xFAFBFCFD, %eax\ncall *%eax\npop %eax\n"
- "wrapper_call: movl $0xFAFBFCFD, %eax\njmp *%eax\n"
+ "wrapper_store: push %edi\npush %esp\npush %ebp\npush %ebx\npush %eax\npush %ecx\npush %edx\n"
+ "wrapper_symbol: pushl $0xFAFBFCFD\n" // arg1 for trace
+ "wrapper_trace: .byte 0xE8, 0xFA, 0xFB, 0xFC, 0xFD\n" // CALL (trace)
+ "wrapper_restore: pop %eax\npop %edx\npop %ecx\npop %eax\npop %ebx\npop %ebp\npop %esp\npop %edi\n"
+ "wrapper_jmp: .byte 0xE9, 0xFA, 0xFB, 0xFC, 0xFD\n" // JMP
+ "wrapper_ud: .byte 0x0F, 0xFF\n" // UD
"wrapper_end: nop\n"
);
# define WRAPPER_TRACE
@@ -46,7 +49,7 @@ __asm__(
#endif
#ifdef WRAPPER_TRACE
-extern char wrapper_start, wrapper_symbol, wrapper_trace, wrapper_call, wrapper_end;
+extern unsigned char wrapper_start, wrapper_symbol, wrapper_trace, wrapper_restore, wrapper_jmp, wrapper_ud, wrapper_end;
static union {
void *ptr;
@@ -104,9 +107,16 @@ wrapper_create(const char *const symbol, void *function)
return NULL;
}
+ return function;
+
#ifdef WRAPPER_TRACE
+ static const union {
+ void *ptr;
+ void (*fun)(const char*);
+ } tracefun = { .fun = trace };
+
const size_t len = strlen(symbol) + 1;
- char *copy = malloc(len);
+ const char *copy = malloc(len);
assert(copy && "welp, malloc failed");
memcpy(copy, symbol, len);
const size_t sz = &wrapper_end - &wrapper_start;
@@ -114,9 +124,16 @@ wrapper_create(const char *const symbol, void *function)
assert(fun != MAP_FAILED);
memcpy(fun, &wrapper_start, sz);
#ifdef ANDROID_X86_LINKER
- memcpy(fun + (&wrapper_symbol - &wrapper_start) + 1, &copy, sizeof(symbol));
- memcpy(fun + (&wrapper_trace - &wrapper_start) + 1, (uintptr_t[]){ (uintptr_t)trace }, sizeof(uintptr_t));
- memcpy(fun + (&wrapper_call - &wrapper_start) + 1, &function, sizeof(function));
+ memcpy(fun + (&wrapper_symbol - &wrapper_start) + 1, &copy, sizeof(copy));
+ {
+ const unsigned char *from = fun + (&wrapper_restore - &wrapper_start);
+ const unsigned char *to = (unsigned char*)tracefun.ptr - from;
+ memcpy(fun + (&wrapper_trace - &wrapper_start) + 1, &to, sizeof(to));
+ }{
+ const unsigned char *from = fun + (&wrapper_ud - &wrapper_start);
+ const unsigned char *to = (unsigned char*)function - from;
+ memcpy(fun + (&wrapper_jmp - &wrapper_start) + 1, &to, sizeof(to));
+ }
#else
# error "you forgot to implement the pointer setups for your asm platform"
#endif