arch/powerpc/kernel/ptrace/ptrace.c

   1 /*
   2  *  PowerPC version
   3  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
   4  *
   5  *  Derived from "arch/m68k/kernel/ptrace.c"
   6  *  Copyright (C) 1994 by Hamish Macdonald
   7  *  Taken from linux/kernel/ptrace.c and modified for M680x0.
   8  *  linux/kernel/ptrace.c is by Ross Biro 1/23/92, edited by Linus Torvalds
   9  *
  10  * Modified by Cort Dougan (cort@hq.fsmlabs.com)
  11  * and Paul Mackerras (paulus@samba.org).
  12  *
  13  * This file is subject to the terms and conditions of the GNU General
  14  * Public License.  See the file README.legal in the main directory of
  15  * this archive for more details.
  16  */
  17
  18 #include <linux/regset.h>
  19 #include <linux/tracehook.h>
  20 #include <linux/audit.h>
  21 #include <linux/context_tracking.h>
  22 #include <linux/syscalls.h>
  23
  24 #include <asm/switch_to.h>
  25 #include <asm/asm-prototypes.h>
  26 #include <asm/debug.h>
  27
  28 #define CREATE_TRACE_POINTS
  29 #include <trace/events/syscalls.h>
  30
  31 #include "ptrace-decl.h"
  32
  33 /*
  34  * Called by kernel/ptrace.c when detaching..
  35  *
  36  * Make sure single step bits etc are not set.
  37  */
  38 void ptrace_disable(struct task_struct *child)
  39 {
  40         /* make sure the single step bit is not set. */
  41         user_disable_single_step(child);
  42 }
  43
  44 long arch_ptrace(struct task_struct *child, long request,
  45                  unsigned long addr, unsigned long data)
  46 {
  47         int ret = -EPERM;
  48         void __user *datavp = (void __user *) data;
  49         unsigned long __user *datalp = datavp;
  50
  51         switch (request) {
  52         /* read the word at location addr in the USER area. */
  53         case PTRACE_PEEKUSR: {
  54                 unsigned long index, tmp;
  55
  56                 ret = -EIO;
  57                 /* convert to index and check */
  58                 index = addr / sizeof(long);
  59                 if ((addr & (sizeof(long) - 1)) || !child->thread.regs)
  60                         break;
  61
  62                 CHECK_FULL_REGS(child->thread.regs);
  63                 if (index < PT_FPR0)
  64                         ret = ptrace_get_reg(child, (int) index, &tmp);
  65                 else
  66                         ret = ptrace_get_fpr(child, index, &tmp);
  67
  68                 if (ret)
  69                         break;
  70                 ret = put_user(tmp, datalp);
  71                 break;
  72         }
  73
  74         /* write the word at location addr in the USER area */
  75         case PTRACE_POKEUSR: {
  76                 unsigned long index;
  77
  78                 ret = -EIO;
  79                 /* convert to index and check */
  80                 index = addr / sizeof(long);
  81                 if ((addr & (sizeof(long) - 1)) || !child->thread.regs)
  82                         break;
  83
  84                 CHECK_FULL_REGS(child->thread.regs);
  85                 if (index < PT_FPR0)
  86                         ret = ptrace_put_reg(child, index, data);
  87                 else
  88                         ret = ptrace_put_fpr(child, index, data);
  89                 break;
  90         }
  91
  92         case PPC_PTRACE_GETHWDBGINFO: {
  93                 struct ppc_debug_info dbginfo;
  94
  95                 ppc_gethwdinfo(&dbginfo);
  96
  97                 if (copy_to_user(datavp, &dbginfo,
  98                                  sizeof(struct ppc_debug_info)))
  99                         return -EFAULT;
 100                 return 0;
 101         }
 102
 103         case PPC_PTRACE_SETHWDEBUG: {
 104                 struct ppc_hw_breakpoint bp_info;
 105
 106                 if (copy_from_user(&bp_info, datavp,
 107                                    sizeof(struct ppc_hw_breakpoint)))
 108                         return -EFAULT;
 109                 return ppc_set_hwdebug(child, &bp_info);
 110         }
 111
 112         case PPC_PTRACE_DELHWDEBUG: {
 113                 ret = ppc_del_hwdebug(child, data);
 114                 break;
 115         }
 116
 117         case PTRACE_GET_DEBUGREG:
 118                 ret = ptrace_get_debugreg(child, addr, datalp);
 119                 break;
 120
 121         case PTRACE_SET_DEBUGREG:
 122                 ret = ptrace_set_debugreg(child, addr, data);
 123                 break;
 124
 125 #ifdef CONFIG_PPC64
 126         case PTRACE_GETREGS64:
 127 #endif
 128         case PTRACE_GETREGS:    /* Get all pt_regs from the child. */
 129                 return copy_regset_to_user(child, &user_ppc_native_view,
 130                                            REGSET_GPR,
 131                                            0, sizeof(struct user_pt_regs),
 132                                            datavp);
 133
 134 #ifdef CONFIG_PPC64
 135         case PTRACE_SETREGS64:
 136 #endif
 137         case PTRACE_SETREGS:    /* Set all gp regs in the child. */
 138                 return copy_regset_from_user(child, &user_ppc_native_view,
 139                                              REGSET_GPR,
 140                                              0, sizeof(struct user_pt_regs),
 141                                              datavp);
 142
 143         case PTRACE_GETFPREGS: /* Get the child FPU state (FPR0...31 + FPSCR) */
 144                 return copy_regset_to_user(child, &user_ppc_native_view,
 145                                            REGSET_FPR,
 146                                            0, sizeof(elf_fpregset_t),
 147                                            datavp);
 148
 149         case PTRACE_SETFPREGS: /* Set the child FPU state (FPR0...31 + FPSCR) */
 150                 return copy_regset_from_user(child, &user_ppc_native_view,
 151                                              REGSET_FPR,
 152                                              0, sizeof(elf_fpregset_t),
 153                                              datavp);
 154
 155 #ifdef CONFIG_ALTIVEC
 156         case PTRACE_GETVRREGS:
 157                 return copy_regset_to_user(child, &user_ppc_native_view,
 158                                            REGSET_VMX,
 159                                            0, (33 * sizeof(vector128) +
 160                                                sizeof(u32)),
 161                                            datavp);
 162
 163         case PTRACE_SETVRREGS:
 164                 return copy_regset_from_user(child, &user_ppc_native_view,
 165                                              REGSET_VMX,
 166                                              0, (33 * sizeof(vector128) +
 167                                                  sizeof(u32)),
 168                                              datavp);
 169 #endif
 170 #ifdef CONFIG_VSX
 171         case PTRACE_GETVSRREGS:
 172                 return copy_regset_to_user(child, &user_ppc_native_view,
 173                                            REGSET_VSX,
 174                                            0, 32 * sizeof(double),
 175                                            datavp);
 176
 177         case PTRACE_SETVSRREGS:
 178                 return copy_regset_from_user(child, &user_ppc_native_view,
 179                                              REGSET_VSX,
 180                                              0, 32 * sizeof(double),
 181                                              datavp);
 182 #endif
 183 #ifdef CONFIG_SPE
 184         case PTRACE_GETEVRREGS:
 185                 /* Get the child spe register state. */
 186                 return copy_regset_to_user(child, &user_ppc_native_view,
 187                                            REGSET_SPE, 0, 35 * sizeof(u32),
 188                                            datavp);
 189
 190         case PTRACE_SETEVRREGS:
 191                 /* Set the child spe register state. */
 192                 return copy_regset_from_user(child, &user_ppc_native_view,
 193                                              REGSET_SPE, 0, 35 * sizeof(u32),
 194                                              datavp);
 195 #endif
 196
 197         default:
 198                 ret = ptrace_request(child, request, addr, data);
 199                 break;
 200         }
 201         return ret;
 202 }
 203
 204 #ifdef CONFIG_SECCOMP
 205 static int do_seccomp(struct pt_regs *regs)
 206 {
 207         if (!test_thread_flag(TIF_SECCOMP))
 208                 return 0;
 209
 210         /*
 211          * The ABI we present to seccomp tracers is that r3 contains
 212          * the syscall return value and orig_gpr3 contains the first
 213          * syscall parameter. This is different to the ptrace ABI where
 214          * both r3 and orig_gpr3 contain the first syscall parameter.
 215          */
 216         regs->gpr[3] = -ENOSYS;
 217
 218         /*
 219          * We use the __ version here because we have already checked
 220          * TIF_SECCOMP. If this fails, there is nothing left to do, we
 221          * have already loaded -ENOSYS into r3, or seccomp has put
 222          * something else in r3 (via SECCOMP_RET_ERRNO/TRACE).
 223          */
 224         if (__secure_computing(NULL))
 225                 return -1;
 226
 227         /*
 228          * The syscall was allowed by seccomp, restore the register
 229          * state to what audit expects.
 230          * Note that we use orig_gpr3, which means a seccomp tracer can
 231          * modify the first syscall parameter (in orig_gpr3) and also
 232          * allow the syscall to proceed.
 233          */
 234         regs->gpr[3] = regs->orig_gpr3;
 235
 236         return 0;
 237 }
 238 #else
 239 static inline int do_seccomp(struct pt_regs *regs) { return 0; }
 240 #endif /* CONFIG_SECCOMP */
 241
 242 /**
 243  * do_syscall_trace_enter() - Do syscall tracing on kernel entry.
 244  * @regs: the pt_regs of the task to trace (current)
 245  *
 246  * Performs various types of tracing on syscall entry. This includes seccomp,
 247  * ptrace, syscall tracepoints and audit.
 248  *
 249  * The pt_regs are potentially visible to userspace via ptrace, so their
 250  * contents is ABI.
 251  *
 252  * One or more of the tracers may modify the contents of pt_regs, in particular
 253  * to modify arguments or even the syscall number itself.
 254  *
 255  * It's also possible that a tracer can choose to reject the system call. In
 256  * that case this function will return an illegal syscall number, and will put
 257  * an appropriate return value in regs->r3.
 258  *
 259  * Return: the (possibly changed) syscall number.
 260  */
 261 long do_syscall_trace_enter(struct pt_regs *regs)
 262 {
 263         u32 flags;
 264
 265         user_exit();
 266
 267         flags = READ_ONCE(current_thread_info()->flags) &
 268                 (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE);
 269
 270         if (flags) {
 271                 int rc = tracehook_report_syscall_entry(regs);
 272
 273                 if (unlikely(flags & _TIF_SYSCALL_EMU)) {
 274                         /*
 275                          * A nonzero return code from
 276                          * tracehook_report_syscall_entry() tells us to prevent
 277                          * the syscall execution, but we are not going to
 278                          * execute it anyway.
 279                          *
 280                          * Returning -1 will skip the syscall execution. We want
 281                          * to avoid clobbering any registers, so we don't goto
 282                          * the skip label below.
 283                          */
 284                         return -1;
 285                 }
 286
 287                 if (rc) {
 288                         /*
 289                          * The tracer decided to abort the syscall. Note that
 290                          * the tracer may also just change regs->gpr[0] to an
 291                          * invalid syscall number, that is handled below on the
 292                          * exit path.
 293                          */
 294                         goto skip;
 295                 }
 296         }
 297
 298         /* Run seccomp after ptrace; allow it to set gpr[3]. */
 299         if (do_seccomp(regs))
 300                 return -1;
 301
 302         /* Avoid trace and audit when syscall is invalid. */
 303         if (regs->gpr[0] >= NR_syscalls)
 304                 goto skip;
 305
 306         if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
 307                 trace_sys_enter(regs, regs->gpr[0]);
 308
 309         if (!is_32bit_task())
 310                 audit_syscall_entry(regs->gpr[0], regs->gpr[3], regs->gpr[4],
 311                                     regs->gpr[5], regs->gpr[6]);
 312         else
 313                 audit_syscall_entry(regs->gpr[0],
 314                                     regs->gpr[3] & 0xffffffff,
 315                                     regs->gpr[4] & 0xffffffff,
 316                                     regs->gpr[5] & 0xffffffff,
 317                                     regs->gpr[6] & 0xffffffff);
 318
 319         /* Return the possibly modified but valid syscall number */
 320         return regs->gpr[0];
 321
 322 skip:
 323         /*
 324          * If we are aborting explicitly, or if the syscall number is
 325          * now invalid, set the return value to -ENOSYS.
 326          */
 327         regs->gpr[3] = -ENOSYS;
 328         return -1;
 329 }
 330
 331 void do_syscall_trace_leave(struct pt_regs *regs)
 332 {
 333         int step;
 334
 335         audit_syscall_exit(regs);
 336
 337         if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
 338                 trace_sys_exit(regs, regs->result);
 339
 340         step = test_thread_flag(TIF_SINGLESTEP);
 341         if (step || test_thread_flag(TIF_SYSCALL_TRACE))
 342                 tracehook_report_syscall_exit(regs, step);
 343
 344         user_enter();
 345 }
 346
 347 void __init pt_regs_check(void);
 348
 349 /*
 350  * Dummy function, its purpose is to break the build if struct pt_regs and
 351  * struct user_pt_regs don't match.
 352  */
 353 void __init pt_regs_check(void)
 354 {
 355         BUILD_BUG_ON(offsetof(struct pt_regs, gpr) !=
 356                      offsetof(struct user_pt_regs, gpr));
 357         BUILD_BUG_ON(offsetof(struct pt_regs, nip) !=
 358                      offsetof(struct user_pt_regs, nip));
 359         BUILD_BUG_ON(offsetof(struct pt_regs, msr) !=
 360                      offsetof(struct user_pt_regs, msr));
 361         BUILD_BUG_ON(offsetof(struct pt_regs, msr) !=
 362                      offsetof(struct user_pt_regs, msr));
 363         BUILD_BUG_ON(offsetof(struct pt_regs, orig_gpr3) !=
 364                      offsetof(struct user_pt_regs, orig_gpr3));
 365         BUILD_BUG_ON(offsetof(struct pt_regs, ctr) !=
 366                      offsetof(struct user_pt_regs, ctr));
 367         BUILD_BUG_ON(offsetof(struct pt_regs, link) !=
 368                      offsetof(struct user_pt_regs, link));
 369         BUILD_BUG_ON(offsetof(struct pt_regs, xer) !=
 370                      offsetof(struct user_pt_regs, xer));
 371         BUILD_BUG_ON(offsetof(struct pt_regs, ccr) !=
 372                      offsetof(struct user_pt_regs, ccr));
 373 #ifdef __powerpc64__
 374         BUILD_BUG_ON(offsetof(struct pt_regs, softe) !=
 375                      offsetof(struct user_pt_regs, softe));
 376 #else
 377         BUILD_BUG_ON(offsetof(struct pt_regs, mq) !=
 378                      offsetof(struct user_pt_regs, mq));
 379 #endif
 380         BUILD_BUG_ON(offsetof(struct pt_regs, trap) !=
 381                      offsetof(struct user_pt_regs, trap));
 382         BUILD_BUG_ON(offsetof(struct pt_regs, dar) !=
 383                      offsetof(struct user_pt_regs, dar));
 384         BUILD_BUG_ON(offsetof(struct pt_regs, dsisr) !=
 385                      offsetof(struct user_pt_regs, dsisr));
 386         BUILD_BUG_ON(offsetof(struct pt_regs, result) !=
 387                      offsetof(struct user_pt_regs, result));
 388
 389         BUILD_BUG_ON(sizeof(struct user_pt_regs) > sizeof(struct pt_regs));
 390
 391         // Now check that the pt_regs offsets match the uapi #defines
 392         #define CHECK_REG(_pt, _reg) \
 393                 BUILD_BUG_ON(_pt != (offsetof(struct user_pt_regs, _reg) / \
 394                                      sizeof(unsigned long)));
 395
 396         CHECK_REG(PT_R0,  gpr[0]);
 397         CHECK_REG(PT_R1,  gpr[1]);
 398         CHECK_REG(PT_R2,  gpr[2]);
 399         CHECK_REG(PT_R3,  gpr[3]);
 400         CHECK_REG(PT_R4,  gpr[4]);
 401         CHECK_REG(PT_R5,  gpr[5]);
 402         CHECK_REG(PT_R6,  gpr[6]);
 403         CHECK_REG(PT_R7,  gpr[7]);
 404         CHECK_REG(PT_R8,  gpr[8]);
 405         CHECK_REG(PT_R9,  gpr[9]);
 406         CHECK_REG(PT_R10, gpr[10]);
 407         CHECK_REG(PT_R11, gpr[11]);
 408         CHECK_REG(PT_R12, gpr[12]);
 409         CHECK_REG(PT_R13, gpr[13]);
 410         CHECK_REG(PT_R14, gpr[14]);
 411         CHECK_REG(PT_R15, gpr[15]);
 412         CHECK_REG(PT_R16, gpr[16]);
 413         CHECK_REG(PT_R17, gpr[17]);
 414         CHECK_REG(PT_R18, gpr[18]);
 415         CHECK_REG(PT_R19, gpr[19]);
 416         CHECK_REG(PT_R20, gpr[20]);
 417         CHECK_REG(PT_R21, gpr[21]);
 418         CHECK_REG(PT_R22, gpr[22]);
 419         CHECK_REG(PT_R23, gpr[23]);
 420         CHECK_REG(PT_R24, gpr[24]);
 421         CHECK_REG(PT_R25, gpr[25]);
 422         CHECK_REG(PT_R26, gpr[26]);
 423         CHECK_REG(PT_R27, gpr[27]);
 424         CHECK_REG(PT_R28, gpr[28]);
 425         CHECK_REG(PT_R29, gpr[29]);
 426         CHECK_REG(PT_R30, gpr[30]);
 427         CHECK_REG(PT_R31, gpr[31]);
 428         CHECK_REG(PT_NIP, nip);
 429         CHECK_REG(PT_MSR, msr);
 430         CHECK_REG(PT_ORIG_R3, orig_gpr3);
 431         CHECK_REG(PT_CTR, ctr);
 432         CHECK_REG(PT_LNK, link);
 433         CHECK_REG(PT_XER, xer);
 434         CHECK_REG(PT_CCR, ccr);
 435 #ifdef CONFIG_PPC64
 436         CHECK_REG(PT_SOFTE, softe);
 437 #else
 438         CHECK_REG(PT_MQ, mq);
 439 #endif
 440         CHECK_REG(PT_TRAP, trap);
 441         CHECK_REG(PT_DAR, dar);
 442         CHECK_REG(PT_DSISR, dsisr);
 443         CHECK_REG(PT_RESULT, result);
 444         #undef CHECK_REG
 445
 446         BUILD_BUG_ON(PT_REGS_COUNT != sizeof(struct user_pt_regs) / sizeof(unsigned long));
 447
 448         /*
 449          * PT_DSCR isn't a real reg, but it's important that it doesn't overlap the
 450          * real registers.
 451          */
 452         BUILD_BUG_ON(PT_DSCR < sizeof(struct user_pt_regs) / sizeof(unsigned long));
 453 }