Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=47571 Signed-off-by: Brendan Shanks bshanks@codeweavers.com --- dlls/ntdll/signal_i386.c | 333 ++++++++++++++++++++++++++++++++- dlls/ntdll/signal_x86_64.c | 374 ++++++++++++++++++++++++++++++++++++- 2 files changed, 691 insertions(+), 16 deletions(-)
diff --git a/dlls/ntdll/signal_i386.c b/dlls/ntdll/signal_i386.c index e9dd0de2fc..e999ae8c20 100644 --- a/dlls/ntdll/signal_i386.c +++ b/dlls/ntdll/signal_i386.c @@ -1521,37 +1521,301 @@ __ASM_STDCALL_FUNC( NtGetContextThread, 8, __ASM_CFI(".cfi_same_value %ebp\n\t") "ret $8" )
+/*********************************************************************** + * User-Mode Instruction Prevention (UMIP) is an x86 feature that prevents user-space + * code (CPL > 0) from executing the sgdt, sidt, sldt, smsw, and str instructions. + * If one of these instructions is executed, a general protection fault is issued. + * + * UMIP was first implemented by the AMD Zen2 and Intel Sunny Cove microarchitectures + * (both released in 2019). + * + * On Linux: + * The kernel traps the GPF and emulates sgdt, sidt, and smsw. + * sldt and str are not emulated. + * + * When the kernel doesn't emulate an instruction, the process receives a SIGSEGV. + * emulate_umip_instr() emulates all instructions not emulated by the Linux kernel. + */ + +/* Dummy LDT, matches what I see on Windows and Linux */ +#define UMIP_DUMMY_LDT 0 + +/* Dummy task register, matches what I see on Windows and Linux */ +#define UMIP_DUMMY_TR 0x40 + +static void *get_reg_address( CONTEXT *context, BYTE rm ) +{ + switch (rm & 7) + { + case 0: return &context->Eax; + case 1: return &context->Ecx; + case 2: return &context->Edx; + case 3: return &context->Ebx; + case 4: return &context->Esp; + case 5: return &context->Ebp; + case 6: return &context->Esi; + case 7: return &context->Edi; + } + return NULL; +} + +/*********************************************************************** + * INSTR_GetOperandAddr + * + * Return the address of an instruction operand (from the mod/rm byte). + */ +static int INSTR_GetOperandAddr( CONTEXT *context, BYTE *instr, unsigned int instr_len, + int long_addr, int segprefix, int *len, void **addr ) +{ + int mod, rm, base = 0, index = 0, ss = 0, off; + unsigned int i = 0; + +#define GET_VAL( val, type ) \ + { if (sizeof(type) > (instr_len - i)) return 0; \ + *val = *(type *)&instr[i]; i += sizeof(type); *len += sizeof(type); } + + *len = 0; + GET_VAL( &mod, BYTE ); + rm = mod & 7; + mod >>= 6; + + if (mod == 3) + { + *addr = get_reg_address( context, rm ); + return 1; + } + + if (long_addr) + { + if (rm == 4) + { + BYTE sib; + GET_VAL( &sib, BYTE ); + rm = sib & 7; + ss = sib >> 6; + switch((sib >> 3) & 7) + { + case 0: index = context->Eax; break; + case 1: index = context->Ecx; break; + case 2: index = context->Edx; break; + case 3: index = context->Ebx; break; + case 4: index = 0; break; + case 5: index = context->Ebp; break; + case 6: index = context->Esi; break; + case 7: index = context->Edi; break; + } + } + + switch(rm) + { + case 0: base = context->Eax; break; + case 1: base = context->Ecx; break; + case 2: base = context->Edx; break; + case 3: base = context->Ebx; break; + case 4: base = context->Esp; break; + case 5: base = context->Ebp; break; + case 6: base = context->Esi; break; + case 7: base = context->Edi; break; + } + switch (mod) + { + case 0: + if (rm == 5) /* special case: ds:(disp32) */ + { + GET_VAL( &base, DWORD ); + } + break; + + case 1: /* 8-bit disp */ + GET_VAL( &off, BYTE ); + base += (signed char)off; + break; + + case 2: /* 32-bit disp */ + GET_VAL( &off, DWORD ); + base += (signed long)off; + break; + } + } + else /* short address */ + { + switch(rm) + { + case 0: /* ds:(bx,si) */ + base = LOWORD(context->Ebx) + LOWORD(context->Esi); + break; + case 1: /* ds:(bx,di) */ + base = LOWORD(context->Ebx) + LOWORD(context->Edi); + break; + case 2: /* ss:(bp,si) */ + base = LOWORD(context->Ebp) + LOWORD(context->Esi); + break; + case 3: /* ss:(bp,di) */ + base = LOWORD(context->Ebp) + LOWORD(context->Edi); + break; + case 4: /* ds:(si) */ + base = LOWORD(context->Esi); + break; + case 5: /* ds:(di) */ + base = LOWORD(context->Edi); + break; + case 6: /* ss:(bp) */ + base = LOWORD(context->Ebp); + break; + case 7: /* ds:(bx) */ + base = LOWORD(context->Ebx); + break; + } + + switch(mod) + { + case 0: + if (rm == 6) /* special case: ds:(disp16) */ + { + GET_VAL( &base, WORD ); + } + break; + + case 1: /* 8-bit disp */ + GET_VAL( &off, BYTE ); + base += (signed char)off; + break; + + case 2: /* 16-bit disp */ + GET_VAL( &off, WORD ); + base += (signed short)off; + break; + } + base &= 0xffff; + } + /* FIXME: we assume that all segments have a base of 0 */ + *addr = (void *)(base + (index << ss)); + return 1; +#undef GET_VAL +} + +/*********************************************************************** + * emulate_umip_instr + * + * Emulate a UMIP-protected instruction. + * Returns: 0 if no instruction emulated, + * 1 if instruction's write to memory failed, + * 2 if instruction emulated successfully. + */ +static int emulate_umip_instr( CONTEXT *context, BYTE *instr, unsigned int len, void **err_addr, + int segprefix, unsigned int prefixlen, int long_op, int long_addr ) +{ + if (len < 2) return 0; + + if (instr[0] == 0x00) /* sldt/str */ + { + int reg = (instr[1] >> 3) & 7; + switch (reg) + { + case 0: /* sldt */ + case 1: /* str */ + { + int instr_len; + int mod = instr[1] >> 6; + void *data; + UINT16 dummy_value; + + if (!INSTR_GetOperandAddr( context, &instr[1], len - 1, long_addr, + segprefix, &instr_len, &data )) + return 0; + + if (reg == 0) + { + /* sldt */ + dummy_value = UMIP_DUMMY_LDT; + TRACE( "sldt at 0x%08x\n", context->Eip ); + } + else + { + /* str */ + dummy_value = UMIP_DUMMY_TR; + TRACE( "str at 0x%08x\n", context->Eip ); + } + + if (mod == 3) + { + /* Destination operand is a register. + * Zero-extend the dummy value and store to the register. */ + UINT32 dummy_value_32 = dummy_value; + memcpy( data, &dummy_value_32, long_op ? 4 : 2 ); + } + else + { + /* Destination operand is a memory location. + * Only copy 16 bits regardless of operand size. */ + if (virtual_uninterrupted_write_memory( data, &dummy_value, sizeof(dummy_value) )) + { + TRACE( "memory write by 0x%08x to %p failed\n", context->Eip, data ); + *err_addr = data; + return 1; + } + } + context->Eip += prefixlen + instr_len + 2; + return 2; + } + } + } + else if (instr[0] == 0x01) /* sgdt/sidt/str */ + { + /* The Linux kernel already emulates these instructions for 32-bit processes, + * Wine should never get an exception for them. + * However, it may be necessary in the future to emulate these instructions + * for other OSes if they don't do any emulation. + */ + } + + return 0; +}
/*********************************************************************** * is_privileged_instr * - * Check if the fault location is a privileged instruction. + * Check if the fault location is a privileged instruction, and emulate a UMIP-protected instruction if found. * Based on the instruction emulation code in dlls/kernel/instr.c. + * Returns: 0 if no privileged instruction found or emulation failed, + * 1 if instruction found and ExceptionCode has been set, + * 2 if instruction was successfully emulated. */ -static inline DWORD is_privileged_instr( CONTEXT *context ) +static inline int is_privileged_instr( CONTEXT *context, EXCEPTION_RECORD *rec ) { BYTE instr[16]; unsigned int i, len, prefix_count = 0; + int long_op = 1, long_addr = 1; + int segprefix = -1; /* no prefix */
if (!wine_ldt_is_system( context->SegCs )) return 0; len = virtual_uninterrupted_read_memory( (BYTE *)context->Eip, instr, sizeof(instr) );
- for (i = 0; i < len; i++) switch (instr[i]) + for (i = 0; i < len; i++) + { + switch (instr[i]) { /* instruction prefixes */ case 0x2e: /* %cs: */ + segprefix = context->SegCs; prefix_count++; break; case 0x36: /* %ss: */ + segprefix = context->SegSs; prefix_count++; break; case 0x3e: /* %ds: */ + segprefix = context->SegDs; prefix_count++; break; case 0x26: /* %es: */ + segprefix = context->SegEs; prefix_count++; break; case 0x64: /* %fs: */ + segprefix = context->SegFs; prefix_count++; break; case 0x65: /* %gs: */ + segprefix = context->SegGs; prefix_count++; break; case 0x66: /* opcode size */ + long_op = !long_op; prefix_count++; break; case 0x67: /* addr size */ + long_addr = !long_addr; prefix_count++; break; case 0xf0: /* lock */ case 0xf2: /* repne */ case 0xf3: /* repe */ - if (++prefix_count >= 15) return EXCEPTION_ILLEGAL_INSTRUCTION; - continue; + prefix_count++; break;
case 0x0f: /* extended instruction */ if (i == len - 1) return 0; @@ -1561,7 +1825,24 @@ static inline DWORD is_privileged_instr( CONTEXT *context ) case 0x21: /* mov drX, reg */ case 0x22: /* mov reg, crX */ case 0x23: /* mov reg drX */ - return EXCEPTION_PRIV_INSTRUCTION; + rec->ExceptionCode = EXCEPTION_PRIV_INSTRUCTION; + return 1; + + case 0x00: /* sldt/str */ + case 0x01: /* sgdt/sidt/smsw */ + { + void *err_addr; + int result = emulate_umip_instr( context, &instr[i+1], len - i - 1, &err_addr, + segprefix, prefix_count, long_op, long_addr ); + if (result == 1) + { + rec->ExceptionCode = EXCEPTION_ACCESS_VIOLATION; + rec->NumberParameters = 2; + rec->ExceptionInformation[0] = 1; + rec->ExceptionInformation[1] = (ULONG_PTR)err_addr; + } + return result; + } } return 0; case 0x6c: /* insb (%dx) */ @@ -1580,10 +1861,14 @@ static inline DWORD is_privileged_instr( CONTEXT *context ) case 0xf4: /* hlt */ case 0xfa: /* cli */ case 0xfb: /* sti */ - return EXCEPTION_PRIV_INSTRUCTION; + rec->ExceptionCode = EXCEPTION_PRIV_INSTRUCTION; + return 1; default: return 0; } + + if (prefix_count >= 15) { rec->ExceptionCode = EXCEPTION_ILLEGAL_INSTRUCTION; return 1; } + } return 0; }
@@ -1994,6 +2279,39 @@ static void segv_handler( int signal, siginfo_t *siginfo, void *sigcontext ) } }
+ /* is_privileged_instr() needs to run before setup_exception_record(). In case an instruction is + * successfully emulated, creating a stack frame may corrupt data. + */ + if (get_trap_code(context) == TRAP_x86_PROTFLT) + { + int result; + CONTEXT localcontext; + EXCEPTION_RECORD rec; + + save_context( &localcontext, sigcontext, fs, gs ); + rec.NumberParameters = 0; + + if (!get_error_code(context) && (result = is_privileged_instr( &localcontext, &rec ))) + { + if (result == 1) + { + stack = setup_exception_record( context, stack_ptr, fs, gs ); + if (stack->rec.ExceptionCode == EXCEPTION_STACK_OVERFLOW) goto done; + + stack->context = localcontext; + stack->rec.ExceptionCode = rec.ExceptionCode; + if (rec.NumberParameters) + { + stack->rec.NumberParameters = rec.NumberParameters; + stack->rec.ExceptionInformation[0] = rec.ExceptionInformation[0]; + stack->rec.ExceptionInformation[1] = rec.ExceptionInformation[1]; + } + goto done; + } + else { restore_context( &localcontext, sigcontext ); return; } + } + } + stack = setup_exception_record( context, stack_ptr, fs, gs ); if (stack->rec.ExceptionCode == EXCEPTION_STACK_OVERFLOW) goto done;
@@ -2016,7 +2334,6 @@ static void segv_handler( int signal, siginfo_t *siginfo, void *sigcontext ) case TRAP_x86_UNKNOWN: /* Unknown fault code */ { WORD err = get_error_code(context); - if (!err && (stack->rec.ExceptionCode = is_privileged_instr( &stack->context ))) break; if ((err & 7) == 2 && handle_interrupt( err >> 3, context, stack )) return; stack->rec.ExceptionCode = EXCEPTION_ACCESS_VIOLATION; stack->rec.NumberParameters = 2; diff --git a/dlls/ntdll/signal_x86_64.c b/dlls/ntdll/signal_x86_64.c index 04f3854388..be743f8178 100644 --- a/dlls/ntdll/signal_x86_64.c +++ b/dlls/ntdll/signal_x86_64.c @@ -2752,25 +2752,326 @@ static void setup_raise_exception( ucontext_t *sigcontext, struct stack_layout * EFL_sig(sigcontext) &= ~(0x100|0x400|0x40000); }
+/*********************************************************************** + * User-Mode Instruction Prevention (UMIP) is an x86 feature that prevents user-space + * code (CPL > 0) from executing the sgdt, sidt, sldt, smsw, and str instructions. + * If one of these instructions is executed, a general protection fault is issued. + * + * UMIP was first implemented by the AMD Zen2 and Intel Sunny Cove microarchitectures + * (both released in 2019). + * + * On Linux: + * Kernel 5.4 and newer emulate sgdt, sidt, and smsw. sldt and str are not emulated. + * Kernels older than v5.4 do not emulate any instructions. + * + * When the kernel doesn't emulate an instruction, the process receives a SIGSEGV. + * emulate_umip_instr() emulates all instructions not emulated by the Linux kernel. + */ + +/* Dummy base addresses are the same as used by the kernel */ +#define UMIP_DUMMY_GDT_BASE 0xfffffffffffe0000ULL +#define UMIP_DUMMY_IDT_BASE 0xffffffffffff0000ULL +#define UMIP_DUMMY_GDT_IDT_LIMIT 0 + +#define UMIP_GDT_IDT_BASE_SIZE_64BIT 8 +#define UMIP_GDT_IDT_LIMIT_SIZE 2 + +/* Dummy LDT, matches what I see on Windows and Linux */ +#define UMIP_DUMMY_LDT 0 + +/* Dummy task register, matches what I see on Windows and Linux */ +#define UMIP_DUMMY_TR 0x40 + +/* Dummy MSW is same value used by kernel, defined as: + * (X86_CR0_PE | X86_CR0_MP | X86_CR0_ET | + * X86_CR0_NE | X86_CR0_WP | X86_CR0_AM | + * X86_CR0_PG) + */ +#define UMIP_DUMMY_MSW 0x33 + +#define REX_B 1 +#define REX_X 2 +#define REX_R 4 +#define REX_W 8 + +#define REGMODRM_MOD( regmodrm, rex ) ((regmodrm) >> 6) +#define REGMODRM_REG( regmodrm, rex ) (((regmodrm) >> 3) & 7) | (((rex) & REX_R) ? 8 : 0) +#define REGMODRM_RM( regmodrm, rex ) (((regmodrm) & 7) | (((rex) & REX_B) ? 8 : 0)) + +#define SIB_SS( sib, rex ) ((sib) >> 6) +#define SIB_INDEX( sib, rex ) (((sib) >> 3) & 7) | (((rex) & REX_X) ? 8 : 0) +#define SIB_BASE( sib, rex ) (((sib) & 7) | (((rex) & REX_B) ? 8 : 0)) + +static inline DWORD64 *get_int_reg_ptr( CONTEXT *context, int index ) +{ + return &context->Rax + index; /* index should be in range 0 .. 15 */ +} + +static inline int get_op_size( int long_op, int rex ) +{ + if (rex & REX_W) + return sizeof(DWORD64); + else if (long_op) + return sizeof(DWORD); + else + return sizeof(WORD); +} + +/*********************************************************************** + * INSTR_GetOperandAddr + * + * Return the address of an instruction operand (from the mod/rm byte). + */ +static int INSTR_GetOperandAddr( CONTEXT *context, BYTE *instr, unsigned int instr_len, + unsigned int addl_instr_len, int long_addr, int rex, int segprefix, + int *len, BYTE **addr ) +{ + int mod, rm, ss = 0, off, have_sib = 0; + unsigned int i = 0; + DWORD64 base = 0, index = 0; + +#define GET_VAL( val, type ) \ + { if (sizeof(type) > (instr_len - i)) return 0; \ + *val = *(type *)&instr[i]; i += sizeof(type); *len += sizeof(type); } + + *len = 0; + GET_VAL( &mod, BYTE ); + rm = REGMODRM_RM( mod, rex ); + mod = REGMODRM_MOD( mod, rex ); + + if (mod == 3) + { + *addr = (BYTE *)get_int_reg_ptr( context, rm ); + return 1; + } + + if ((rm & 7) == 4) + { + BYTE sib; + int id; + + GET_VAL( &sib, BYTE ); + rm = SIB_BASE( sib, rex ); + id = SIB_INDEX( sib, rex ); + ss = SIB_SS( sib, rex ); + + index = (id != 4) ? *get_int_reg_ptr( context, id ) : 0; + if (!long_addr) index &= 0xffffffff; + have_sib = 1; + } + + base = *get_int_reg_ptr( context, rm ); + if (!long_addr) base &= 0xffffffff; + + switch (mod) + { + case 0: + if (rm == 5) /* special case */ + { + base = have_sib ? 0 : context->Rip; + if (!long_addr) base &= 0xffffffff; + GET_VAL( &off, DWORD ); + base += (signed long)off; + base += (signed long)*len + (signed long)addl_instr_len; + } + break; + + case 1: /* 8-bit disp */ + GET_VAL( &off, BYTE ); + base += (signed char)off; + break; + + case 2: /* 32-bit disp */ + GET_VAL( &off, DWORD ); + base += (signed long)off; + break; + } + + /* FIXME: we assume that all segments have a base of 0 */ + *addr = (BYTE *)(base + (index << ss)); + return 1; +#undef GET_VAL +} + +/*********************************************************************** + * emulate_umip_instr + * + * Emulate a UMIP-protected instruction. + * Returns: 0 if no instruction emulated, + * 1 if instruction's write to memory failed, + * 2 if instruction emulated successfully. + */ +static int emulate_umip_instr( CONTEXT *context, BYTE *instr, unsigned int len, void **err_addr, + int segprefix, unsigned int prefixlen, int long_op, int long_addr, int rex ) +{ + if (len < 2) return 0; + + if (instr[0] == 0x00) /* sldt/str */ + { + int reg = REGMODRM_REG( instr[1], rex ); + switch (reg) + { + case 0: /* sldt */ + case 1: /* str */ + { + int instr_len; + BYTE *data; + UINT16 dummy_value; + + if (!INSTR_GetOperandAddr( context, &instr[1], len - 1, prefixlen + 2, long_addr, + rex, segprefix, &instr_len, &data )) + return 0; + + if (reg == 0) + { + /* sldt */ + dummy_value = UMIP_DUMMY_LDT; + TRACE( "sldt at 0x%lx\n", context->Rip ); + } + else + { + /* str */ + dummy_value = UMIP_DUMMY_TR; + TRACE( "str at 0x%lx\n", context->Rip ); + } + + if (REGMODRM_MOD( instr[1], rex ) == 3) + { + /* Destination operand is a register. + * Zero-extend the dummy LDT and store to the register. */ + UINT64 dummy_value_64 = dummy_value; + memcpy( data, &dummy_value_64, get_op_size( long_op, rex ) ); + } + else + { + /* Destination operand is a memory location. + * Only copy 16 bits regardless of operand size. */ + if (virtual_uninterrupted_write_memory( data, &dummy_value, sizeof(dummy_value) )) + { + TRACE( "memory write by 0x%lx to %p failed\n", context->Rip, data ); + *err_addr = data; + return 1; + } + } + context->Rip += prefixlen + instr_len + 2; + return 2; + } + default: break; + } + } + else if (instr[0] == 0x01) /* sgdt/sidt/str */ + { + int instr_len; + int reg = REGMODRM_REG( instr[1], rex ); + switch (reg) + { + case 0: /* sgdt */ + case 1: /* sidt */ + { + BYTE *data; + UINT16 dummy_limit = UMIP_DUMMY_GDT_IDT_LIMIT; + UINT64 dummy_base_addr; + + /* sgdt/sidt cannot use a register as the destination operand */ + if (REGMODRM_MOD( instr[1], rex ) == 3) + return 0; + + if (!INSTR_GetOperandAddr( context, &instr[1], len - 1, prefixlen + 2, long_addr, + rex, segprefix, &instr_len, &data )) + return 0; + + if (reg == 0) + { + /* sgdt */ + dummy_base_addr = UMIP_DUMMY_GDT_BASE; + TRACE( "sgdt at %lx\n", context->Rip ); + } + else if (reg == 1) + { + /* sidt */ + dummy_base_addr = UMIP_DUMMY_IDT_BASE; + TRACE( "sidt at %lx\n", context->Rip ); + } + if (virtual_uninterrupted_write_memory( data, &dummy_limit, UMIP_GDT_IDT_LIMIT_SIZE ) || + virtual_uninterrupted_write_memory( data + UMIP_GDT_IDT_LIMIT_SIZE, &dummy_base_addr, UMIP_GDT_IDT_BASE_SIZE_64BIT )) + { + TRACE( "memory write by 0x%lx to %p failed\n", context->Rip, data ); + *err_addr = data; + return 1; + } + + context->Rip += prefixlen + instr_len + 2; + return 2; + } + case 4: /* smsw */ + { + BYTE *data; + + if (!INSTR_GetOperandAddr( context, &instr[1], len - 1, prefixlen + 2, long_addr, + rex, segprefix, &instr_len, &data )) + return 0; + + if (REGMODRM_MOD( instr[1], rex ) == 3) + { + /* Destination operand is a register. + * Zero-extend the dummy MSW and store to the register. */ + UINT64 dummy_msw = UMIP_DUMMY_MSW; + TRACE( "smsw at %lx\n", context->Rip ); + memcpy( data, &dummy_msw, get_op_size( long_op, rex ) ); + } + else + { + /* Destination operand is a memory location. + * Only copy 16 bits regardless of operand size. */ + UINT16 dummy_msw = UMIP_DUMMY_MSW; + TRACE( "smsw at %lx\n", context->Rip ); + if (virtual_uninterrupted_write_memory( data, &dummy_msw, sizeof(dummy_msw) )) + { + TRACE( "memory write by 0x%lx to %p failed\n", context->Rip, data ); + *err_addr = data; + return 1; + } + } + context->Rip += prefixlen + instr_len + 2; + return 2; + } + default: break; + } + } + + return 0; +}
/*********************************************************************** * is_privileged_instr * - * Check if the fault location is a privileged instruction. + * Check if the fault location is a privileged instruction, and emulate a UMIP-protected instruction if found. + * Returns: 0 if no privileged instruction found or emulation failed, + * 1 if instruction found and ExceptionCode has been set, + * 2 if instruction was successfully emulated. */ -static inline DWORD is_privileged_instr( CONTEXT *context ) +static inline int is_privileged_instr( CONTEXT *context, EXCEPTION_RECORD *rec ) { BYTE instr[16]; + int segprefix, long_op = 1, long_addr = 1, rex; unsigned int i, prefix_count = 0; unsigned int len = virtual_uninterrupted_read_memory( (BYTE *)context->Rip, instr, sizeof(instr) );
- for (i = 0; i < len; i++) switch (instr[i]) + segprefix = -1; /* no seg prefix */ + rex = 0; /* no rex prefix */ + for (i = 0; i < len; i++) + { + switch (instr[i]) { /* instruction prefixes */ case 0x2e: /* %cs: */ + segprefix = context->SegCs; prefix_count++; break; case 0x36: /* %ss: */ + segprefix = context->SegSs; prefix_count++; break; case 0x3e: /* %ds: */ + segprefix = context->SegDs; prefix_count++; break; case 0x26: /* %es: */ + segprefix = context->SegEs; prefix_count++; break; case 0x40: /* rex */ case 0x41: /* rex */ case 0x42: /* rex */ @@ -2787,15 +3088,19 @@ static inline DWORD is_privileged_instr( CONTEXT *context ) case 0x4d: /* rex */ case 0x4e: /* rex */ case 0x4f: /* rex */ + rex = instr[i]; prefix_count++; break; case 0x64: /* %fs: */ + segprefix = context->SegFs; prefix_count++; break; case 0x65: /* %gs: */ + segprefix = context->SegGs; prefix_count++; break; case 0x66: /* opcode size */ + long_op = !long_op; prefix_count++; break; case 0x67: /* addr size */ + long_addr = !long_addr; prefix_count++; break; case 0xf0: /* lock */ case 0xf2: /* repne */ case 0xf3: /* repe */ - if (++prefix_count >= 15) return EXCEPTION_ILLEGAL_INSTRUCTION; - continue; + prefix_count++; break;
case 0x0f: /* extended instruction */ if (i == len - 1) return 0; @@ -2808,7 +3113,24 @@ static inline DWORD is_privileged_instr( CONTEXT *context ) case 0x21: /* mov drX, reg */ case 0x22: /* mov reg, crX */ case 0x23: /* mov reg drX */ - return EXCEPTION_PRIV_INSTRUCTION; + rec->ExceptionCode = EXCEPTION_PRIV_INSTRUCTION; + return 1; + + case 0x00: /* sldt/str */ + case 0x01: /* sgdt/sidt/smsw */ + { + void *err_addr; + int result = emulate_umip_instr( context, &instr[i+1], len - i - 1, &err_addr, + segprefix, prefix_count, long_op, long_addr, rex ); + if (result == 1) + { + rec->ExceptionCode = EXCEPTION_ACCESS_VIOLATION; + rec->NumberParameters = 2; + rec->ExceptionInformation[0] = 1; + rec->ExceptionInformation[1] = (ULONG_PTR)err_addr; + } + return result; + } } return 0; case 0x6c: /* insb (%dx) */ @@ -2827,10 +3149,14 @@ static inline DWORD is_privileged_instr( CONTEXT *context ) case 0xf4: /* hlt */ case 0xfa: /* cli */ case 0xfb: /* sti */ - return EXCEPTION_PRIV_INSTRUCTION; + rec->ExceptionCode = EXCEPTION_PRIV_INSTRUCTION; + return 1; default: return 0; } + + if (prefix_count >= 15) { rec->ExceptionCode = EXCEPTION_ILLEGAL_INSTRUCTION; return 1; } + } return 0; }
@@ -2904,6 +3230,39 @@ static void segv_handler( int signal, siginfo_t *siginfo, void *sigcontext ) } }
+ /* is_privileged_instr() needs to run before setup_exception(). In case an instruction is + * successfully emulated, creating a stack frame may corrupt data. + */ + if (TRAP_sig(ucontext) == TRAP_x86_PROTFLT) + { + int result; + CONTEXT context; + EXCEPTION_RECORD rec; + + save_context( &context, sigcontext ); + rec.NumberParameters = 0; + + if (!ERROR_sig(ucontext) && (result = is_privileged_instr( &context, &rec ))) + { + if (result == 1) + { + stack = setup_exception( sigcontext ); + if (stack->rec.ExceptionCode == EXCEPTION_STACK_OVERFLOW) goto done; + + stack->context = context; + stack->rec.ExceptionCode = rec.ExceptionCode; + if (rec.NumberParameters) + { + stack->rec.NumberParameters = rec.NumberParameters; + stack->rec.ExceptionInformation[0] = rec.ExceptionInformation[0]; + stack->rec.ExceptionInformation[1] = rec.ExceptionInformation[1]; + } + goto done; + } + else { restore_context( &context, sigcontext ); return; } + } + } + stack = setup_exception( sigcontext ); if (stack->rec.ExceptionCode == EXCEPTION_STACK_OVERFLOW) goto done;
@@ -2926,7 +3285,6 @@ static void segv_handler( int signal, siginfo_t *siginfo, void *sigcontext ) case TRAP_x86_UNKNOWN: /* Unknown fault code */ { WORD err = ERROR_sig(ucontext); - if (!err && (stack->rec.ExceptionCode = is_privileged_instr( &stack->context ))) break; if ((err & 7) == 2 && handle_interrupt( ucontext, stack )) return; stack->rec.ExceptionCode = EXCEPTION_ACCESS_VIOLATION; stack->rec.NumberParameters = 2;