diff options
Diffstat (limited to 'arch/x86/kernel/ptrace.c')
| -rw-r--r-- | arch/x86/kernel/ptrace.c | 484 |
1 files changed, 484 insertions, 0 deletions
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c new file mode 100644 index 000000000000..fed83d066135 --- /dev/null +++ b/arch/x86/kernel/ptrace.c @@ -0,0 +1,484 @@ +/* By Ross Biro 1/23/92 */ +/* + * Pentium III FXSR, SSE support + * Gareth Hughes <gareth@valinux.com>, May 2000 + */ + +#include <linux/kernel.h> +#include <linux/sched.h> +#include <linux/mm.h> +#include <linux/smp.h> +#include <linux/errno.h> +#include <linux/ptrace.h> +#include <linux/user.h> +#include <linux/security.h> +#include <linux/audit.h> +#include <linux/seccomp.h> +#include <linux/signal.h> + +#include <asm/uaccess.h> +#include <asm/pgtable.h> +#include <asm/system.h> +#include <asm/processor.h> +#include <asm/i387.h> +#include <asm/debugreg.h> +#include <asm/ldt.h> +#include <asm/desc.h> + +/* + * does not yet catch signals sent when the child dies. + * in exit.c or in signal.c. + */ + +/* + * Determines which flags the user has access to [1 = access, 0 = no access]. + * Prohibits changing ID(21), VIP(20), VIF(19), VM(17), NT(14), IOPL(12-13), IF(9). + * Also masks reserved bits (31-22, 15, 5, 3, 1). + */ +#define FLAG_MASK 0x00050dd5 + +static long *pt_regs_access(struct pt_regs *regs, unsigned long regno) +{ + BUILD_BUG_ON(offsetof(struct pt_regs, bx) != 0); + if (regno > FS) + --regno; + return ®s->bx + regno; +} + +static int putreg(struct task_struct *child, + unsigned long regno, unsigned long value) +{ + struct pt_regs *regs = task_pt_regs(child); + regno >>= 2; + switch (regno) { + case GS: + if (value && (value & 3) != 3) + return -EIO; + child->thread.gs = value; + if (child == current) + /* + * The user-mode %gs is not affected by + * kernel entry, so we must update the CPU. + */ + loadsegment(gs, value); + return 0; + case DS: + case ES: + case FS: + if (value && (value & 3) != 3) + return -EIO; + value &= 0xffff; + break; + case SS: + case CS: + if ((value & 3) != 3) + return -EIO; + value &= 0xffff; + break; + case EFL: + value &= FLAG_MASK; + /* + * If the user value contains TF, mark that + * it was not "us" (the debugger) that set it. + * If not, make sure it stays set if we had. + */ + if (value & X86_EFLAGS_TF) + clear_tsk_thread_flag(child, TIF_FORCED_TF); + else if (test_tsk_thread_flag(child, TIF_FORCED_TF)) + value |= X86_EFLAGS_TF; + value |= regs->flags & ~FLAG_MASK; + break; + } + *pt_regs_access(regs, regno) = value; + return 0; +} + +static unsigned long getreg(struct task_struct *child, unsigned long regno) +{ + struct pt_regs *regs = task_pt_regs(child); + unsigned long retval = ~0UL; + + regno >>= 2; + switch (regno) { + case EFL: + /* + * If the debugger set TF, hide it from the readout. + */ + retval = regs->flags; + if (test_tsk_thread_flag(child, TIF_FORCED_TF)) + retval &= ~X86_EFLAGS_TF; + break; + case GS: + retval = child->thread.gs; + if (child == current) + savesegment(gs, retval); + break; + case DS: + case ES: + case FS: + case SS: + case CS: + retval = 0xffff; + /* fall through */ + default: + retval &= *pt_regs_access(regs, regno); + } + return retval; +} + +/* + * This function is trivial and will be inlined by the compiler. + * Having it separates the implementation details of debug + * registers from the interface details of ptrace. + */ +static unsigned long ptrace_get_debugreg(struct task_struct *child, int n) +{ + switch (n) { + case 0: return child->thread.debugreg0; + case 1: return child->thread.debugreg1; + case 2: return child->thread.debugreg2; + case 3: return child->thread.debugreg3; + case 6: return child->thread.debugreg6; + case 7: return child->thread.debugreg7; + } + return 0; +} + +static int ptrace_set_debugreg(struct task_struct *child, + int n, unsigned long data) +{ + int i; + + if (unlikely(n == 4 || n == 5)) + return -EIO; + + if (n < 4 && unlikely(data >= TASK_SIZE - 3)) + return -EIO; + + switch (n) { + case 0: child->thread.debugreg0 = data; break; + case 1: child->thread.debugreg1 = data; break; + case 2: child->thread.debugreg2 = data; break; + case 3: child->thread.debugreg3 = data; break; + + case 6: + child->thread.debugreg6 = data; + break; + + case 7: + /* + * Sanity-check data. Take one half-byte at once with + * check = (val >> (16 + 4*i)) & 0xf. It contains the + * R/Wi and LENi bits; bits 0 and 1 are R/Wi, and bits + * 2 and 3 are LENi. Given a list of invalid values, + * we do mask |= 1 << invalid_value, so that + * (mask >> check) & 1 is a correct test for invalid + * values. + * + * R/Wi contains the type of the breakpoint / + * watchpoint, LENi contains the length of the watched + * data in the watchpoint case. + * + * The invalid values are: + * - LENi == 0x10 (undefined), so mask |= 0x0f00. + * - R/Wi == 0x10 (break on I/O reads or writes), so + * mask |= 0x4444. + * - R/Wi == 0x00 && LENi != 0x00, so we have mask |= + * 0x1110. + * + * Finally, mask = 0x0f00 | 0x4444 | 0x1110 == 0x5f54. + * + * See the Intel Manual "System Programming Guide", + * 15.2.4 + * + * Note that LENi == 0x10 is defined on x86_64 in long + * mode (i.e. even for 32-bit userspace software, but + * 64-bit kernel), so the x86_64 mask value is 0x5454. + * See the AMD manual no. 24593 (AMD64 System Programming) + */ + data &= ~DR_CONTROL_RESERVED; + for (i = 0; i < 4; i++) + if ((0x5f54 >> ((data >> (16 + 4*i)) & 0xf)) & 1) + return -EIO; + child->thread.debugreg7 = data; + if (data) + set_tsk_thread_flag(child, TIF_DEBUG); + else + clear_tsk_thread_flag(child, TIF_DEBUG); + break; + } + + return 0; +} + +/* + * Called by kernel/ptrace.c when detaching.. + * + * Make sure the single step bit is not set. + */ +void ptrace_disable(struct task_struct *child) +{ + user_disable_single_step(child); + clear_tsk_thread_flag(child, TIF_SYSCALL_EMU); +} + +long arch_ptrace(struct task_struct *child, long request, long addr, long data) +{ + struct user * dummy = NULL; + int i, ret; + unsigned long __user *datap = (unsigned long __user *)data; + + switch (request) { + /* when I and D space are separate, these will need to be fixed. */ + case PTRACE_PEEKTEXT: /* read word at location addr. */ + case PTRACE_PEEKDATA: + ret = generic_ptrace_peekdata(child, addr, data); + break; + + /* read the word at location addr in the USER area. */ + case PTRACE_PEEKUSR: { + unsigned long tmp; + + ret = -EIO; + if ((addr & 3) || addr < 0 || + addr > sizeof(struct user) - 3) + break; + + tmp = 0; /* Default return condition */ + if(addr < FRAME_SIZE*sizeof(long)) + tmp = getreg(child, addr); + if(addr >= (long) &dummy->u_debugreg[0] && + addr <= (long) &dummy->u_debugreg[7]){ + addr -= (long) &dummy->u_debugreg[0]; + addr = addr >> 2; + tmp = ptrace_get_debugreg(child, addr); + } + ret = put_user(tmp, datap); + break; + } + + /* when I and D space are separate, this will have to be fixed. */ + case PTRACE_POKETEXT: /* write the word at location addr. */ + case PTRACE_POKEDATA: + ret = generic_ptrace_pokedata(child, addr, data); + break; + + case PTRACE_POKEUSR: /* write the word at location addr in the USER area */ + ret = -EIO; + if ((addr & 3) || addr < 0 || + addr > sizeof(struct user) - 3) + break; + + if (addr < FRAME_SIZE*sizeof(long)) { + ret = putreg(child, addr, data); + break; + } + /* We need to be very careful here. We implicitly + want to modify a portion of the task_struct, and we + have to be selective about what portions we allow someone + to modify. */ + + ret = -EIO; + if(addr >= (long) &dummy->u_debugreg[0] && + addr <= (long) &dummy->u_debugreg[7]){ + addr -= (long) &dummy->u_debugreg; + addr = addr >> 2; + ret = ptrace_set_debugreg(child, addr, data); + } + break; + + case PTRACE_GETREGS: { /* Get all gp regs from the child. */ + if (!access_ok(VERIFY_WRITE, datap, FRAME_SIZE*sizeof(long))) { + ret = -EIO; + break; + } + for ( i = 0; i < FRAME_SIZE*sizeof(long); i += sizeof(long) ) { + __put_user(getreg(child, i), datap); + datap++; + } + ret = 0; + break; + } + + case PTRACE_SETREGS: { /* Set all gp regs in the child. */ + unsigned long tmp; + if (!access_ok(VERIFY_READ, datap, FRAME_SIZE*sizeof(long))) { + ret = -EIO; + break; + } + for ( i = 0; i < FRAME_SIZE*sizeof(long); i += sizeof(long) ) { + __get_user(tmp, datap); + putreg(child, i, tmp); + datap++; + } + ret = 0; + break; + } + + case PTRACE_GETFPREGS: { /* Get the child FPU state. */ + if (!access_ok(VERIFY_WRITE, datap, + sizeof(struct user_i387_struct))) { + ret = -EIO; + break; + } + ret = 0; + if (!tsk_used_math(child)) + init_fpu(child); + get_fpregs((struct user_i387_struct __user *)data, child); + break; + } + + case PTRACE_SETFPREGS: { /* Set the child FPU state. */ + if (!access_ok(VERIFY_READ, datap, + sizeof(struct user_i387_struct))) { + ret = -EIO; + break; + } + set_stopped_child_used_math(child); + set_fpregs(child, (struct user_i387_struct __user *)data); + ret = 0; + break; + } + + case PTRACE_GETFPXREGS: { /* Get the child extended FPU state. */ + if (!access_ok(VERIFY_WRITE, datap, + sizeof(struct user_fxsr_struct))) { + ret = -EIO; + break; + } + if (!tsk_used_math(child)) + init_fpu(child); + ret = get_fpxregs((struct user_fxsr_struct __user *)data, child); + break; + } + + case PTRACE_SETFPXREGS: { /* Set the child extended FPU state. */ + if (!access_ok(VERIFY_READ, datap, + sizeof(struct user_fxsr_struct))) { + ret = -EIO; + break; + } + set_stopped_child_used_math(child); + ret = set_fpxregs(child, (struct user_fxsr_struct __user *)data); + break; + } + + case PTRACE_GET_THREAD_AREA: + if (addr < 0) + return -EIO; + ret = do_get_thread_area(child, addr, + (struct user_desc __user *) data); + break; + + case PTRACE_SET_THREAD_AREA: + if (addr < 0) + return -EIO; + ret = do_set_thread_area(child, addr, + (struct user_desc __user *) data, 0); + break; + + default: + ret = ptrace_request(child, request, addr, data); + break; + } + + return ret; +} + +void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs, int error_code) +{ + struct siginfo info; + + tsk->thread.trap_no = 1; + tsk->thread.error_code = error_code; + + memset(&info, 0, sizeof(info)); + info.si_signo = SIGTRAP; + info.si_code = TRAP_BRKPT; + + /* User-mode ip? */ + info.si_addr = user_mode_vm(regs) ? (void __user *) regs->ip : NULL; + + /* Send us the fake SIGTRAP */ + force_sig_info(SIGTRAP, &info, tsk); +} + +/* notification of system call entry/exit + * - triggered by current->work.syscall_trace + */ +__attribute__((regparm(3))) +int do_syscall_trace(struct pt_regs *regs, int entryexit) +{ + int is_sysemu = test_thread_flag(TIF_SYSCALL_EMU); + /* + * With TIF_SYSCALL_EMU set we want to ignore TIF_SINGLESTEP for syscall + * interception + */ + int is_singlestep = !is_sysemu && test_thread_flag(TIF_SINGLESTEP); + int ret = 0; + + /* do the secure computing check first */ + if (!entryexit) + secure_computing(regs->orig_ax); + + if (unlikely(current->audit_context)) { + if (entryexit) + audit_syscall_exit(AUDITSC_RESULT(regs->ax), + regs->ax); + /* Debug traps, when using PTRACE_SINGLESTEP, must be sent only + * on the syscall exit path. Normally, when TIF_SYSCALL_AUDIT is + * not used, entry.S will call us only on syscall exit, not + * entry; so when TIF_SYSCALL_AUDIT is used we must avoid + * calling send_sigtrap() on syscall entry. + * + * Note that when PTRACE_SYSEMU_SINGLESTEP is used, + * is_singlestep is false, despite his name, so we will still do + * the correct thing. + */ + else if (is_singlestep) + goto out; + } + + if (!(current->ptrace & PT_PTRACED)) + goto out; + + /* If a process stops on the 1st tracepoint with SYSCALL_TRACE + * and then is resumed with SYSEMU_SINGLESTEP, it will come in + * here. We have to check this and return */ + if (is_sysemu && entryexit) + return 0; + + /* Fake a debug trap */ + if (is_singlestep) + send_sigtrap(current, regs, 0); + + if (!test_thread_flag(TIF_SYSCALL_TRACE) && !is_sysemu) + goto out; + + /* the 0x80 provides a way for the tracing parent to distinguish + between a syscall stop and SIGTRAP delivery */ + /* Note that the debugger could change the result of test_thread_flag!*/ + ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD) ? 0x80:0)); + + /* + * this isn't the same as continuing with a signal, but it will do + * for normal use. strace only continues with a signal if the + * stopping signal is not SIGTRAP. -brl + */ + if (current->exit_code) { + send_sig(current->exit_code, current, 1); + current->exit_code = 0; + } + ret = is_sysemu; +out: + if (unlikely(current->audit_context) && !entryexit) + audit_syscall_entry(AUDIT_ARCH_I386, regs->orig_ax, + regs->bx, regs->cx, regs->dx, regs->si); + if (ret == 0) + return 0; + + regs->orig_ax = -1; /* force skip of syscall restarting */ + if (unlikely(current->audit_context)) + audit_syscall_exit(AUDITSC_RESULT(regs->ax), regs->ax); + return 1; +} |