diff options
Diffstat (limited to 'gdb/common/linux-ptrace.c')
| -rw-r--r-- | gdb/common/linux-ptrace.c | 553 |
1 files changed, 0 insertions, 553 deletions
diff --git a/gdb/common/linux-ptrace.c b/gdb/common/linux-ptrace.c deleted file mode 100644 index b140b08..0000000 --- a/gdb/common/linux-ptrace.c +++ /dev/null @@ -1,553 +0,0 @@ -/* Linux-specific ptrace manipulation routines. - Copyright (C) 2012-2014 Free Software Foundation, Inc. - - This file is part of GDB. - - This program is free software; you can redistribute it and/or modify - it under the terms of the GNU General Public License as published by - the Free Software Foundation; either version 3 of the License, or - (at your option) any later version. - - This program is distributed in the hope that it will be useful, - but WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - GNU General Public License for more details. - - You should have received a copy of the GNU General Public License - along with this program. If not, see <http://www.gnu.org/licenses/>. */ - -#ifdef GDBSERVER -#include "server.h" -#else -#include "defs.h" -#include <string.h> -#endif - -#include "linux-ptrace.h" -#include "linux-procfs.h" -#include "nat/linux-waitpid.h" -#include "buffer.h" -#include "gdb_assert.h" -#include "gdb_wait.h" - -#include <stdint.h> - -/* Stores the currently supported ptrace options. A value of - -1 means we did not check for features yet. A value of 0 means - there are no supported features. */ -static int current_ptrace_options = -1; - -/* Find all possible reasons we could fail to attach PID and append - these as strings to the already initialized BUFFER. '\0' - termination of BUFFER must be done by the caller. */ - -void -linux_ptrace_attach_fail_reason (pid_t pid, struct buffer *buffer) -{ - pid_t tracerpid; - - tracerpid = linux_proc_get_tracerpid (pid); - if (tracerpid > 0) - buffer_xml_printf (buffer, _("process %d is already traced " - "by process %d"), - (int) pid, (int) tracerpid); - - if (linux_proc_pid_is_zombie (pid)) - buffer_xml_printf (buffer, _("process %d is a zombie " - "- the process has already terminated"), - (int) pid); -} - -#if defined __i386__ || defined __x86_64__ - -/* Address of the 'ret' instruction in asm code block below. */ -extern void (linux_ptrace_test_ret_to_nx_instr) (void); - -#include <sys/reg.h> -#include <sys/mman.h> -#include <signal.h> - -#endif /* defined __i386__ || defined __x86_64__ */ - -/* Test broken off-trunk Linux kernel patchset for NX support on i386. It was - removed in Fedora kernel 88fa1f0332d188795ed73d7ac2b1564e11a0b4cd. - - Test also x86_64 arch for PaX support. */ - -static void -linux_ptrace_test_ret_to_nx (void) -{ -#if defined __i386__ || defined __x86_64__ - pid_t child, got_pid; - gdb_byte *return_address, *pc; - long l; - int status, kill_status; - - return_address = mmap (NULL, 2, PROT_READ | PROT_WRITE, - MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); - if (return_address == MAP_FAILED) - { - warning (_("linux_ptrace_test_ret_to_nx: Cannot mmap: %s"), - strerror (errno)); - return; - } - - /* Put there 'int3'. */ - *return_address = 0xcc; - - child = fork (); - switch (child) - { - case -1: - warning (_("linux_ptrace_test_ret_to_nx: Cannot fork: %s"), - strerror (errno)); - return; - - case 0: - l = ptrace (PTRACE_TRACEME, 0, (PTRACE_TYPE_ARG3) NULL, - (PTRACE_TYPE_ARG4) NULL); - if (l != 0) - warning (_("linux_ptrace_test_ret_to_nx: Cannot PTRACE_TRACEME: %s"), - strerror (errno)); - else - { -#if defined __i386__ - asm volatile ("pushl %0;" - ".globl linux_ptrace_test_ret_to_nx_instr;" - "linux_ptrace_test_ret_to_nx_instr:" - "ret" - : : "r" (return_address) : "%esp", "memory"); -#elif defined __x86_64__ - asm volatile ("pushq %0;" - ".globl linux_ptrace_test_ret_to_nx_instr;" - "linux_ptrace_test_ret_to_nx_instr:" - "ret" - : : "r" ((uint64_t) (uintptr_t) return_address) - : "%rsp", "memory"); -#else -# error "!__i386__ && !__x86_64__" -#endif - gdb_assert_not_reached ("asm block did not terminate"); - } - - _exit (1); - } - - errno = 0; - got_pid = waitpid (child, &status, 0); - if (got_pid != child) - { - warning (_("linux_ptrace_test_ret_to_nx: waitpid returned %ld: %s"), - (long) got_pid, strerror (errno)); - return; - } - - if (WIFSIGNALED (status)) - { - if (WTERMSIG (status) != SIGKILL) - warning (_("linux_ptrace_test_ret_to_nx: WTERMSIG %d is not SIGKILL!"), - (int) WTERMSIG (status)); - else - warning (_("Cannot call inferior functions, Linux kernel PaX " - "protection forbids return to non-executable pages!")); - return; - } - - if (!WIFSTOPPED (status)) - { - warning (_("linux_ptrace_test_ret_to_nx: status %d is not WIFSTOPPED!"), - status); - return; - } - - /* We may get SIGSEGV due to missing PROT_EXEC of the return_address. */ - if (WSTOPSIG (status) != SIGTRAP && WSTOPSIG (status) != SIGSEGV) - { - warning (_("linux_ptrace_test_ret_to_nx: " - "WSTOPSIG %d is neither SIGTRAP nor SIGSEGV!"), - (int) WSTOPSIG (status)); - return; - } - - errno = 0; -#if defined __i386__ - l = ptrace (PTRACE_PEEKUSER, child, (PTRACE_TYPE_ARG3) (uintptr_t) (EIP * 4), - (PTRACE_TYPE_ARG4) NULL); -#elif defined __x86_64__ - l = ptrace (PTRACE_PEEKUSER, child, (PTRACE_TYPE_ARG3) (uintptr_t) (RIP * 8), - (PTRACE_TYPE_ARG4) NULL); -#else -# error "!__i386__ && !__x86_64__" -#endif - if (errno != 0) - { - warning (_("linux_ptrace_test_ret_to_nx: Cannot PTRACE_PEEKUSER: %s"), - strerror (errno)); - return; - } - pc = (void *) (uintptr_t) l; - - kill (child, SIGKILL); - ptrace (PTRACE_KILL, child, (PTRACE_TYPE_ARG3) NULL, - (PTRACE_TYPE_ARG4) NULL); - - errno = 0; - got_pid = waitpid (child, &kill_status, 0); - if (got_pid != child) - { - warning (_("linux_ptrace_test_ret_to_nx: " - "PTRACE_KILL waitpid returned %ld: %s"), - (long) got_pid, strerror (errno)); - return; - } - if (!WIFSIGNALED (kill_status)) - { - warning (_("linux_ptrace_test_ret_to_nx: " - "PTRACE_KILL status %d is not WIFSIGNALED!"), - status); - return; - } - - /* + 1 is there as x86* stops after the 'int3' instruction. */ - if (WSTOPSIG (status) == SIGTRAP && pc == return_address + 1) - { - /* PASS */ - return; - } - - /* We may get SIGSEGV due to missing PROT_EXEC of the RETURN_ADDRESS page. */ - if (WSTOPSIG (status) == SIGSEGV && pc == return_address) - { - /* PASS */ - return; - } - - if ((void (*) (void)) pc != &linux_ptrace_test_ret_to_nx_instr) - warning (_("linux_ptrace_test_ret_to_nx: PC %p is neither near return " - "address %p nor is the return instruction %p!"), - pc, return_address, &linux_ptrace_test_ret_to_nx_instr); - else - warning (_("Cannot call inferior functions on this system - " - "Linux kernel with broken i386 NX (non-executable pages) " - "support detected!")); -#endif /* defined __i386__ || defined __x86_64__ */ -} - -/* Helper function to fork a process and make the child process call - the function FUNCTION, passing CHILD_STACK as parameter. - - For MMU-less targets, clone is used instead of fork, and - CHILD_STACK is used as stack space for the cloned child. If NULL, - stack space is allocated via malloc (and subsequently passed to - FUNCTION). For MMU targets, CHILD_STACK is ignored. */ - -static int -linux_fork_to_function (gdb_byte *child_stack, void (*function) (gdb_byte *)) -{ - int child_pid; - - /* Sanity check the function pointer. */ - gdb_assert (function != NULL); - -#if defined(__UCLIBC__) && defined(HAS_NOMMU) -#define STACK_SIZE 4096 - - if (child_stack == NULL) - child_stack = xmalloc (STACK_SIZE * 4); - - /* Use CLONE_VM instead of fork, to support uClinux (no MMU). */ -#ifdef __ia64__ - child_pid = __clone2 (function, child_stack, STACK_SIZE, - CLONE_VM | SIGCHLD, child_stack + STACK_SIZE * 2); -#else /* !__ia64__ */ - child_pid = clone (function, child_stack + STACK_SIZE, - CLONE_VM | SIGCHLD, child_stack + STACK_SIZE * 2); -#endif /* !__ia64__ */ -#else /* !defined(__UCLIBC) && defined(HAS_NOMMU) */ - child_pid = fork (); - - if (child_pid == 0) - function (NULL); -#endif /* defined(__UCLIBC) && defined(HAS_NOMMU) */ - - if (child_pid == -1) - perror_with_name (("fork")); - - return child_pid; -} - -/* A helper function for linux_check_ptrace_features, called after - the child forks a grandchild. */ - -static void -linux_grandchild_function (gdb_byte *child_stack) -{ - /* Free any allocated stack. */ - xfree (child_stack); - - /* This code is only reacheable by the grandchild (child's child) - process. */ - _exit (0); -} - -/* A helper function for linux_check_ptrace_features, called after - the parent process forks a child. The child allows itself to - be traced by its parent. */ - -static void -linux_child_function (gdb_byte *child_stack) -{ - ptrace (PTRACE_TRACEME, 0, (PTRACE_TYPE_ARG3) 0, (PTRACE_TYPE_ARG4) 0); - kill (getpid (), SIGSTOP); - - /* Fork a grandchild. */ - linux_fork_to_function (child_stack, linux_grandchild_function); - - /* This code is only reacheable by the child (grandchild's parent) - process. */ - _exit (0); -} - -static void linux_test_for_tracesysgood (int child_pid); -static void linux_test_for_tracefork (int child_pid); - -/* Determine ptrace features available on this target. */ - -static void -linux_check_ptrace_features (void) -{ - int child_pid, ret, status; - - /* Initialize the options. */ - current_ptrace_options = 0; - - /* Fork a child so we can do some testing. The child will call - linux_child_function and will get traced. The child will - eventually fork a grandchild so we can test fork event - reporting. */ - child_pid = linux_fork_to_function (NULL, linux_child_function); - - ret = my_waitpid (child_pid, &status, 0); - if (ret == -1) - perror_with_name (("waitpid")); - else if (ret != child_pid) - error (_("linux_check_ptrace_features: waitpid: unexpected result %d."), - ret); - if (! WIFSTOPPED (status)) - error (_("linux_check_ptrace_features: waitpid: unexpected status %d."), - status); - - linux_test_for_tracesysgood (child_pid); - - linux_test_for_tracefork (child_pid); - - /* Clean things up and kill any pending children. */ - do - { - ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_TYPE_ARG3) 0, - (PTRACE_TYPE_ARG4) 0); - if (ret != 0) - warning (_("linux_check_ptrace_features: failed to kill child")); - my_waitpid (child_pid, &status, 0); - } - while (WIFSTOPPED (status)); -} - -/* Determine if PTRACE_O_TRACESYSGOOD can be used to catch - syscalls. */ - -static void -linux_test_for_tracesysgood (int child_pid) -{ -#ifdef GDBSERVER - /* gdbserver does not support PTRACE_O_TRACESYSGOOD. */ -#else - int ret; - - ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0, - (PTRACE_TYPE_ARG4) PTRACE_O_TRACESYSGOOD); - if (ret == 0) - current_ptrace_options |= PTRACE_O_TRACESYSGOOD; -#endif -} - -/* Determine if PTRACE_O_TRACEFORK can be used to follow fork - events. */ - -static void -linux_test_for_tracefork (int child_pid) -{ - int ret, status; - long second_pid; - - /* First, set the PTRACE_O_TRACEFORK option. If this fails, we - know for sure that it is not supported. */ - ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0, - (PTRACE_TYPE_ARG4) PTRACE_O_TRACEFORK); - - if (ret != 0) - return; - -#ifdef GDBSERVER - /* gdbserver does not support PTRACE_O_TRACEVFORKDONE yet. */ -#else - /* Check if the target supports PTRACE_O_TRACEVFORKDONE. */ - ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0, - (PTRACE_TYPE_ARG4) (PTRACE_O_TRACEFORK - | PTRACE_O_TRACEVFORKDONE)); - if (ret == 0) - current_ptrace_options |= PTRACE_O_TRACEVFORKDONE; -#endif - - /* Setting PTRACE_O_TRACEFORK did not cause an error, however we - don't know for sure that the feature is available; old - versions of PTRACE_SETOPTIONS ignored unknown options. - Therefore, we attach to the child process, use PTRACE_SETOPTIONS - to enable fork tracing, and let it fork. If the process exits, - we assume that we can't use PTRACE_O_TRACEFORK; if we get the - fork notification, and we can extract the new child's PID, then - we assume that we can. - - We do not explicitly check for vfork tracing here. It is - assumed that vfork tracing is available whenever fork tracing - is available. */ - ret = ptrace (PTRACE_CONT, child_pid, (PTRACE_TYPE_ARG3) 0, - (PTRACE_TYPE_ARG4) 0); - if (ret != 0) - warning (_("linux_test_for_tracefork: failed to resume child")); - - ret = my_waitpid (child_pid, &status, 0); - - /* Check if we received a fork event notification. */ - if (ret == child_pid && WIFSTOPPED (status) - && status >> 16 == PTRACE_EVENT_FORK) - { - /* We did receive a fork event notification. Make sure its PID - is reported. */ - second_pid = 0; - ret = ptrace (PTRACE_GETEVENTMSG, child_pid, (PTRACE_TYPE_ARG3) 0, - (PTRACE_TYPE_ARG4) &second_pid); - if (ret == 0 && second_pid != 0) - { - int second_status; - - /* We got the PID from the grandchild, which means fork - tracing is supported. */ -#ifdef GDBSERVER - /* Do not enable all the options for now since gdbserver does not - properly support them. This restriction will be lifted when - gdbserver is augmented to support them. */ - current_ptrace_options |= PTRACE_O_TRACECLONE; -#else - current_ptrace_options |= PTRACE_O_TRACEFORK | PTRACE_O_TRACEVFORK - | PTRACE_O_TRACECLONE | PTRACE_O_TRACEEXEC; - - /* Do not enable PTRACE_O_TRACEEXIT until GDB is more prepared to - support read-only process state. */ -#endif - - /* Do some cleanup and kill the grandchild. */ - my_waitpid (second_pid, &second_status, 0); - ret = ptrace (PTRACE_KILL, second_pid, (PTRACE_TYPE_ARG3) 0, - (PTRACE_TYPE_ARG4) 0); - if (ret != 0) - warning (_("linux_test_for_tracefork: " - "failed to kill second child")); - my_waitpid (second_pid, &status, 0); - } - } - else - warning (_("linux_test_for_tracefork: unexpected result from waitpid " - "(%d, status 0x%x)"), ret, status); -} - -/* Enable reporting of all currently supported ptrace events. */ - -void -linux_enable_event_reporting (pid_t pid) -{ - /* Check if we have initialized the ptrace features for this - target. If not, do it now. */ - if (current_ptrace_options == -1) - linux_check_ptrace_features (); - - /* Set the options. */ - ptrace (PTRACE_SETOPTIONS, pid, (PTRACE_TYPE_ARG3) 0, - (PTRACE_TYPE_ARG4) (uintptr_t) current_ptrace_options); -} - -/* Disable reporting of all currently supported ptrace events. */ - -void -linux_disable_event_reporting (pid_t pid) -{ - /* Set the options. */ - ptrace (PTRACE_SETOPTIONS, pid, (PTRACE_TYPE_ARG3) 0, 0); -} - -/* Returns non-zero if PTRACE_OPTIONS is contained within - CURRENT_PTRACE_OPTIONS, therefore supported. Returns 0 - otherwise. */ - -static int -ptrace_supports_feature (int ptrace_options) -{ - gdb_assert (current_ptrace_options >= 0); - - return ((current_ptrace_options & ptrace_options) == ptrace_options); -} - -/* Returns non-zero if PTRACE_EVENT_FORK is supported by ptrace, - 0 otherwise. Note that if PTRACE_EVENT_FORK is supported so is - PTRACE_EVENT_CLONE, PTRACE_EVENT_EXEC and PTRACE_EVENT_VFORK, - since they were all added to the kernel at the same time. */ - -int -linux_supports_tracefork (void) -{ - return ptrace_supports_feature (PTRACE_O_TRACEFORK); -} - -/* Returns non-zero if PTRACE_EVENT_CLONE is supported by ptrace, - 0 otherwise. Note that if PTRACE_EVENT_CLONE is supported so is - PTRACE_EVENT_FORK, PTRACE_EVENT_EXEC and PTRACE_EVENT_VFORK, - since they were all added to the kernel at the same time. */ - -int -linux_supports_traceclone (void) -{ - return ptrace_supports_feature (PTRACE_O_TRACECLONE); -} - -/* Returns non-zero if PTRACE_O_TRACEVFORKDONE is supported by - ptrace, 0 otherwise. */ - -int -linux_supports_tracevforkdone (void) -{ - return ptrace_supports_feature (PTRACE_O_TRACEVFORKDONE); -} - -/* Returns non-zero if PTRACE_O_TRACESYSGOOD is supported by ptrace, - 0 otherwise. */ - -int -linux_supports_tracesysgood (void) -{ - return ptrace_supports_feature (PTRACE_O_TRACESYSGOOD); -} - -/* Display possible problems on this system. Display them only once per GDB - execution. */ - -void -linux_ptrace_init_warnings (void) -{ - static int warned = 0; - - if (warned) - return; - warned = 1; - - linux_ptrace_test_ret_to_nx (); -} |