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debug: enhance mmap catch code

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Use nice instruction_HLT macro
Use log_debug_mem()
Don't actually log things after we prohibit 'mmap'.
Move initialization of strerror & udev before blocking mmap.
This commit is contained in:
Zdenek Kabelac 2014-09-19 11:04:36 +02:00
parent 081e406d0d
commit 386fbf8e0d
1 changed files with 12 additions and 17 deletions
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29
lib/mm/memlock.c
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@ -334,6 +334,7 @@ static int _memlock_maps(struct cmd_context *cmd, lvmlock_t lock, size_t *mstats
#define _GNU_SOURCE #define _GNU_SOURCE
#endif #endif
#include <dlfcn.h> #include <dlfcn.h>
static const unsigned char INSTRUCTION_HLT = 0x94;
static char _mmap_orig; static char _mmap_orig;
static unsigned char *_mmap_addr; static unsigned char *_mmap_addr;
#ifdef __i386__ #ifdef __i386__
@ -358,7 +359,7 @@ static int _disable_mmap(void)
#endif /* __i386__ */ #endif /* __i386__ */
_mmap_addr = *(void **)abs_addr; _mmap_addr = *(void **)abs_addr;
} else } else
log_debug("Can't find PLT jump entry assuming -fPIE linkage."); log_debug_mem("Can't find PLT jump entry assuming -fPIE linkage.");
if (mprotect((void *)((unsigned long)_mmap_addr & ~4095UL), 4096, PROT_READ|PROT_WRITE|PROT_EXEC)) { if (mprotect((void *)((unsigned long)_mmap_addr & ~4095UL), 4096, PROT_READ|PROT_WRITE|PROT_EXEC)) {
log_sys_error("mprotect", ""); log_sys_error("mprotect", "");
_mmap_addr = NULL; _mmap_addr = NULL;
@ -366,8 +367,8 @@ static int _disable_mmap(void)
} }
_mmap_orig = *_mmap_addr; _mmap_orig = *_mmap_addr;
} }
*_mmap_addr = 0xf4; log_debug_mem("Remapping mmap entry %02x to %02x.", _mmap_orig, INSTRUCTION_HLT);
log_debug("Remapped mmap jump entry %x to %x.", _mmap_orig, *_mmap_addr); *_mmap_addr = INSTRUCTION_HLT;
#ifdef __i386__ #ifdef __i386__
if (!_mmap64_addr) { if (!_mmap64_addr) {
@ -375,8 +376,7 @@ static int _disable_mmap(void)
if (_mmap64_addr[0] == 0xff && _mmap64_addr[1] == 0x25) { if (_mmap64_addr[0] == 0xff && _mmap64_addr[1] == 0x25) {
abs_addr = *(void **)(_mmap64_addr + 2); abs_addr = *(void **)(_mmap64_addr + 2);
_mmap64_addr = *(void **)abs_addr; _mmap64_addr = *(void **)abs_addr;
} else } /* Can't find PLT jump entry assuming -fPIE linkage */
log_debug("Can't find PLT jump entry assuming -fPIE linkage.");
if (mprotect((void *)((unsigned long)_mmap64_addr & ~4095UL), 4096, PROT_READ|PROT_WRITE|PROT_EXEC)) { if (mprotect((void *)((unsigned long)_mmap64_addr & ~4095UL), 4096, PROT_READ|PROT_WRITE|PROT_EXEC)) {
log_sys_error("mprotect", ""); log_sys_error("mprotect", "");
_mmap64_addr = NULL; _mmap64_addr = NULL;
@ -384,8 +384,7 @@ static int _disable_mmap(void)
} }
_mmap64_orig = *_mmap64_addr; _mmap64_orig = *_mmap64_addr;
} }
*_mmap64_addr = 0xf4; *_mmap64_addr = INSTRUCTION_HLT;
log_debug("Remapped mmap64 jump entry %x to %x.", _mmap64_orig, *_mmap64_addr);
#endif /* __i386__ */ #endif /* __i386__ */
#endif /* ARCH_X86 */ #endif /* ARCH_X86 */
return 1; return 1;
@ -394,16 +393,13 @@ static int _disable_mmap(void)
static int _restore_mmap(void) static int _restore_mmap(void)
{ {
#ifdef ARCH_X86 #ifdef ARCH_X86
if (_mmap_addr) { if (_mmap_addr)
log_debug("Restoring mmap jump entry.");
*_mmap_addr = _mmap_orig; *_mmap_addr = _mmap_orig;
}
#ifdef __i386__ #ifdef __i386__
if (_mmap64_addr) { if (_mmap64_addr)
log_debug("Restoring mmap64 jump entry.");
*_mmap64_addr = _mmap64_orig; *_mmap64_addr = _mmap64_orig;
}
#endif /* __i386__ */ #endif /* __i386__ */
log_debug_mem("Restored mmap entry.");
#endif /* ARCH_X86 */ #endif /* ARCH_X86 */
return 1; return 1;
} }
@ -412,6 +408,9 @@ static int _restore_mmap(void)
static void _lock_mem(struct cmd_context *cmd) static void _lock_mem(struct cmd_context *cmd)
{ {
_allocate_memory(); _allocate_memory();
(void)strerror(0); /* Force libc.mo load */
(void)dm_udev_get_sync_support(); /* udev is initialized */
log_very_verbose("Locking memory");
/* /*
* For daemon we need to use mlockall() * For daemon we need to use mlockall()
@ -439,10 +438,6 @@ static void _lock_mem(struct cmd_context *cmd)
stack; stack;
} }
(void)strerror(0); /* Force libc.mo load */
(void)dm_udev_get_sync_support(); /* udev is initialized */
log_very_verbose("Locking memory");
if (!_memlock_maps(cmd, LVM_MLOCK, &_mstats)) if (!_memlock_maps(cmd, LVM_MLOCK, &_mstats))
stack; stack;