diff options
Diffstat (limited to 'arch/i386/kernel/ptrace.c')
| -rw-r--r-- | arch/i386/kernel/ptrace.c | 717 |
1 files changed, 717 insertions, 0 deletions
diff --git a/arch/i386/kernel/ptrace.c b/arch/i386/kernel/ptrace.c new file mode 100644 index 000000000000..b2f17640ceff --- /dev/null +++ b/arch/i386/kernel/ptrace.c @@ -0,0 +1,717 @@ +/* ptrace.c */ +/* 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/smp_lock.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 <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 */ +#define FLAG_MASK 0x00044dd5 + +/* set's the trap flag. */ +#define TRAP_FLAG 0x100 + +/* + * Offset of eflags on child stack.. + */ +#define EFL_OFFSET ((EFL-2)*4-sizeof(struct pt_regs)) + +static inline struct pt_regs *get_child_regs(struct task_struct *task) +{ + void *stack_top = (void *)task->thread.esp0; + return stack_top - sizeof(struct pt_regs); +} + +/* + * this routine will get a word off of the processes privileged stack. + * the offset is how far from the base addr as stored in the TSS. + * this routine assumes that all the privileged stacks are in our + * data space. + */ +static inline int get_stack_long(struct task_struct *task, int offset) +{ + unsigned char *stack; + + stack = (unsigned char *)task->thread.esp0; + stack += offset; + return (*((int *)stack)); +} + +/* + * this routine will put a word on the processes privileged stack. + * the offset is how far from the base addr as stored in the TSS. + * this routine assumes that all the privileged stacks are in our + * data space. + */ +static inline int put_stack_long(struct task_struct *task, int offset, + unsigned long data) +{ + unsigned char * stack; + + stack = (unsigned char *) task->thread.esp0; + stack += offset; + *(unsigned long *) stack = data; + return 0; +} + +static int putreg(struct task_struct *child, + unsigned long regno, unsigned long value) +{ + switch (regno >> 2) { + case FS: + if (value && (value & 3) != 3) + return -EIO; + child->thread.fs = value; + return 0; + case GS: + if (value && (value & 3) != 3) + return -EIO; + child->thread.gs = value; + return 0; + case DS: + case ES: + 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; + value |= get_stack_long(child, EFL_OFFSET) & ~FLAG_MASK; + break; + } + if (regno > GS*4) + regno -= 2*4; + put_stack_long(child, regno - sizeof(struct pt_regs), value); + return 0; +} + +static unsigned long getreg(struct task_struct *child, + unsigned long regno) +{ + unsigned long retval = ~0UL; + + switch (regno >> 2) { + case FS: + retval = child->thread.fs; + break; + case GS: + retval = child->thread.gs; + break; + case DS: + case ES: + case SS: + case CS: + retval = 0xffff; + /* fall through */ + default: + if (regno > GS*4) + regno -= 2*4; + regno = regno - sizeof(struct pt_regs); + retval &= get_stack_long(child, regno); + } + return retval; +} + +#define LDT_SEGMENT 4 + +static unsigned long convert_eip_to_linear(struct task_struct *child, struct pt_regs *regs) +{ + unsigned long addr, seg; + + addr = regs->eip; + seg = regs->xcs & 0xffff; + if (regs->eflags & VM_MASK) { + addr = (addr & 0xffff) + (seg << 4); + return addr; + } + + /* + * We'll assume that the code segments in the GDT + * are all zero-based. That is largely true: the + * TLS segments are used for data, and the PNPBIOS + * and APM bios ones we just ignore here. + */ + if (seg & LDT_SEGMENT) { + u32 *desc; + unsigned long base; + + down(&child->mm->context.sem); + desc = child->mm->context.ldt + (seg & ~7); + base = (desc[0] >> 16) | ((desc[1] & 0xff) << 16) | (desc[1] & 0xff000000); + + /* 16-bit code segment? */ + if (!((desc[1] >> 22) & 1)) + addr &= 0xffff; + addr += base; + up(&child->mm->context.sem); + } + return addr; +} + +static inline int is_at_popf(struct task_struct *child, struct pt_regs *regs) +{ + int i, copied; + unsigned char opcode[16]; + unsigned long addr = convert_eip_to_linear(child, regs); + + copied = access_process_vm(child, addr, opcode, sizeof(opcode), 0); + for (i = 0; i < copied; i++) { + switch (opcode[i]) { + /* popf */ + case 0x9d: + return 1; + /* opcode and address size prefixes */ + case 0x66: case 0x67: + continue; + /* irrelevant prefixes (segment overrides and repeats) */ + case 0x26: case 0x2e: + case 0x36: case 0x3e: + case 0x64: case 0x65: + case 0xf0: case 0xf2: case 0xf3: + continue; + + /* + * pushf: NOTE! We should probably not let + * the user see the TF bit being set. But + * it's more pain than it's worth to avoid + * it, and a debugger could emulate this + * all in user space if it _really_ cares. + */ + case 0x9c: + default: + return 0; + } + } + return 0; +} + +static void set_singlestep(struct task_struct *child) +{ + struct pt_regs *regs = get_child_regs(child); + + /* + * Always set TIF_SINGLESTEP - this guarantees that + * we single-step system calls etc.. This will also + * cause us to set TF when returning to user mode. + */ + set_tsk_thread_flag(child, TIF_SINGLESTEP); + + /* + * If TF was already set, don't do anything else + */ + if (regs->eflags & TRAP_FLAG) + return; + + /* Set TF on the kernel stack.. */ + regs->eflags |= TRAP_FLAG; + + /* + * ..but if TF is changed by the instruction we will trace, + * don't mark it as being "us" that set it, so that we + * won't clear it by hand later. + */ + if (is_at_popf(child, regs)) + return; + + child->ptrace |= PT_DTRACE; +} + +static void clear_singlestep(struct task_struct *child) +{ + /* Always clear TIF_SINGLESTEP... */ + clear_tsk_thread_flag(child, TIF_SINGLESTEP); + + /* But touch TF only if it was set by us.. */ + if (child->ptrace & PT_DTRACE) { + struct pt_regs *regs = get_child_regs(child); + regs->eflags &= ~TRAP_FLAG; + child->ptrace &= ~PT_DTRACE; + } +} + +/* + * Called by kernel/ptrace.c when detaching.. + * + * Make sure the single step bit is not set. + */ +void ptrace_disable(struct task_struct *child) +{ + clear_singlestep(child); +} + +/* + * Perform get_thread_area on behalf of the traced child. + */ +static int +ptrace_get_thread_area(struct task_struct *child, + int idx, struct user_desc __user *user_desc) +{ + struct user_desc info; + struct desc_struct *desc; + +/* + * Get the current Thread-Local Storage area: + */ + +#define GET_BASE(desc) ( \ + (((desc)->a >> 16) & 0x0000ffff) | \ + (((desc)->b << 16) & 0x00ff0000) | \ + ( (desc)->b & 0xff000000) ) + +#define GET_LIMIT(desc) ( \ + ((desc)->a & 0x0ffff) | \ + ((desc)->b & 0xf0000) ) + +#define GET_32BIT(desc) (((desc)->b >> 22) & 1) +#define GET_CONTENTS(desc) (((desc)->b >> 10) & 3) +#define GET_WRITABLE(desc) (((desc)->b >> 9) & 1) +#define GET_LIMIT_PAGES(desc) (((desc)->b >> 23) & 1) +#define GET_PRESENT(desc) (((desc)->b >> 15) & 1) +#define GET_USEABLE(desc) (((desc)->b >> 20) & 1) + + if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) + return -EINVAL; + + desc = child->thread.tls_array + idx - GDT_ENTRY_TLS_MIN; + + info.entry_number = idx; + info.base_addr = GET_BASE(desc); + info.limit = GET_LIMIT(desc); + info.seg_32bit = GET_32BIT(desc); + info.contents = GET_CONTENTS(desc); + info.read_exec_only = !GET_WRITABLE(desc); + info.limit_in_pages = GET_LIMIT_PAGES(desc); + info.seg_not_present = !GET_PRESENT(desc); + info.useable = GET_USEABLE(desc); + + if (copy_to_user(user_desc, &info, sizeof(info))) + return -EFAULT; + + return 0; +} + +/* + * Perform set_thread_area on behalf of the traced child. + */ +static int +ptrace_set_thread_area(struct task_struct *child, + int idx, struct user_desc __user *user_desc) +{ + struct user_desc info; + struct desc_struct *desc; + + if (copy_from_user(&info, user_desc, sizeof(info))) + return -EFAULT; + + if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) + return -EINVAL; + + desc = child->thread.tls_array + idx - GDT_ENTRY_TLS_MIN; + if (LDT_empty(&info)) { + desc->a = 0; + desc->b = 0; + } else { + desc->a = LDT_entry_a(&info); + desc->b = LDT_entry_b(&info); + } + + return 0; +} + +asmlinkage int sys_ptrace(long request, long pid, long addr, long data) +{ + struct task_struct *child; + struct user * dummy = NULL; + int i, ret; + unsigned long __user *datap = (unsigned long __user *)data; + + lock_kernel(); + ret = -EPERM; + if (request == PTRACE_TRACEME) { + /* are we already being traced? */ + if (current->ptrace & PT_PTRACED) + goto out; + ret = security_ptrace(current->parent, current); + if (ret) + goto out; + /* set the ptrace bit in the process flags. */ + current->ptrace |= PT_PTRACED; + ret = 0; + goto out; + } + ret = -ESRCH; + read_lock(&tasklist_lock); + child = find_task_by_pid(pid); + if (child) + get_task_struct(child); + read_unlock(&tasklist_lock); + if (!child) + goto out; + + ret = -EPERM; + if (pid == 1) /* you may not mess with init */ + goto out_tsk; + + if (request == PTRACE_ATTACH) { + ret = ptrace_attach(child); + goto out_tsk; + } + + ret = ptrace_check_attach(child, request == PTRACE_KILL); + if (ret < 0) + goto out_tsk; + + 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: { + unsigned long tmp; + int copied; + + copied = access_process_vm(child, addr, &tmp, sizeof(tmp), 0); + ret = -EIO; + if (copied != sizeof(tmp)) + break; + ret = put_user(tmp, datap); + 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 = child->thread.debugreg[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 = 0; + if (access_process_vm(child, addr, &data, sizeof(data), 1) == sizeof(data)) + break; + ret = -EIO; + 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]){ + + if(addr == (long) &dummy->u_debugreg[4]) break; + if(addr == (long) &dummy->u_debugreg[5]) break; + if(addr < (long) &dummy->u_debugreg[4] && + ((unsigned long) data) >= TASK_SIZE-3) break; + + /* 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)*/ + + if(addr == (long) &dummy->u_debugreg[7]) { + data &= ~DR_CONTROL_RESERVED; + for(i=0; i<4; i++) + if ((0x5f54 >> ((data >> (16 + 4*i)) & 0xf)) & 1) + goto out_tsk; + } + + addr -= (long) &dummy->u_debugreg; + addr = addr >> 2; + child->thread.debugreg[addr] = data; + ret = 0; + } + break; + + case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */ + case PTRACE_CONT: /* restart after signal. */ + ret = -EIO; + if ((unsigned long) data > _NSIG) + break; + if (request == PTRACE_SYSCALL) { + set_tsk_thread_flag(child, TIF_SYSCALL_TRACE); + } + else { + clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); + } + child->exit_code = data; + /* make sure the single step bit is not set. */ + clear_singlestep(child); + wake_up_process(child); + ret = 0; + break; + +/* + * make the child exit. Best I can do is send it a sigkill. + * perhaps it should be put in the status that it wants to + * exit. + */ + case PTRACE_KILL: + ret = 0; + if (child->exit_state == EXIT_ZOMBIE) /* already dead */ + break; + child->exit_code = SIGKILL; + /* make sure the single step bit is not set. */ + clear_singlestep(child); + wake_up_process(child); + break; + + case PTRACE_SINGLESTEP: /* set the trap flag. */ + ret = -EIO; + if ((unsigned long) data > _NSIG) + break; + clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); + set_singlestep(child); + child->exit_code = data; + /* give it a chance to run. */ + wake_up_process(child); + ret = 0; + break; + + case PTRACE_DETACH: + /* detach a process that was attached. */ + ret = ptrace_detach(child, 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: + ret = ptrace_get_thread_area(child, addr, + (struct user_desc __user *) data); + break; + + case PTRACE_SET_THREAD_AREA: + ret = ptrace_set_thread_area(child, addr, + (struct user_desc __user *) data); + break; + + default: + ret = ptrace_request(child, request, addr, data); + break; + } +out_tsk: + put_task_struct(child); +out: + unlock_kernel(); + 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 eip? */ + info.si_addr = user_mode(regs) ? (void __user *) regs->eip : NULL; + + /* Send us the fakey SIGTRAP */ + force_sig_info(SIGTRAP, &info, tsk); +} + +/* notification of system call entry/exit + * - triggered by current->work.syscall_trace + */ +__attribute__((regparm(3))) +void do_syscall_trace(struct pt_regs *regs, int entryexit) +{ + /* do the secure computing check first */ + secure_computing(regs->orig_eax); + + if (unlikely(current->audit_context)) { + if (!entryexit) + audit_syscall_entry(current, regs->orig_eax, + regs->ebx, regs->ecx, + regs->edx, regs->esi); + else + audit_syscall_exit(current, regs->eax); + } + + if (!(current->ptrace & PT_PTRACED)) + return; + + /* Fake a debug trap */ + if (test_thread_flag(TIF_SINGLESTEP)) + send_sigtrap(current, regs, 0); + + if (!test_thread_flag(TIF_SYSCALL_TRACE)) + return; + + /* the 0x80 provides a way for the tracing parent to distinguish + between a syscall stop and SIGTRAP delivery */ + 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; + } +} |