debug.c

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/*
 *   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 2 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, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/** Functions to help with debugging
 *
 * @file src/lib/util/debug.c
 *
 * @copyright 2013 The FreeRADIUS server project
 * @copyright 2013 Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 */
#include <freeradius-devel/util/backtrace.h>
#include <freeradius-devel/util/debug.h>
#include <freeradius-devel/util/hash.h>
#include <freeradius-devel/util/strerror.h>
#include <freeradius-devel/util/syserror.h>
 
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/wait.h>
 
#if defined(HAVE_MALLOPT) && defined(HAVE_MALLOC_H)
#  include <malloc.h>
#endif
 
#ifdef HAVE_SYS_PRCTL_H
#  include <sys/prctl.h>
#endif
 
#ifdef HAVE_SYS_PROCCTL_H
#  include <sys/procctl.h>
#endif
 
#ifdef HAVE_SYS_PTRACE_H
#  include <sys/ptrace.h>
#  if !defined(PT_ATTACH) && defined(PTRACE_ATTACH)
#    define PT_ATTACH PTRACE_ATTACH
#  endif
#  if !defined(PT_DETACH) && defined(PTRACE_DETACH)
#    define PT_DETACH PTRACE_DETACH
#  endif
#endif
 
#ifdef HAVE_SYS_RESOURCE_H
#  include <sys/resource.h>
#endif
 
#ifdef __APPLE__
#include <sys/sysctl.h>
#endif
 
static char panic_action[512];                          //!< The command to execute when panicking.
static fr_fault_cb_t panic_cb = NULL;                   //!< Callback to execute whilst panicking, before the
                                                        //!< panic_action.
 
static bool dump_core;                                  //!< Whether we should drop a core on fatal signals.
 
int fr_fault_log_fd = STDERR_FILENO;            //!< Where to write debug output.
 
fr_debug_state_t fr_debug_state = DEBUGGER_STATE_UNKNOWN;       //!< Whether we're attached to by a debugger.
 
#ifdef HAVE_SYS_RESOURCE_H
static struct rlimit init_core_limit;
#endif
 
static TALLOC_CTX *talloc_autofree_ctx;
 
/*
 * On BSD systems, ptrace(PT_DETACH) uses a third argument for
 * resume address, with the magic value (void *)1 to resume where
 * process stopped. Specifying NULL there leads to a crash because
 * process resumes at address 0.
 */
#if defined(HAVE_SYS_PTRACE_H)
#  ifdef __linux__
#    define _PTRACE(_x, _y) ptrace(_x, _y, NULL, NULL)
#    define _PTRACE_DETACH(_x) ptrace(PT_DETACH, _x, NULL, NULL)
#  elif !defined(__APPLE__) && !defined(__EMSCRIPTEN__) && !defined(HAVE_SYS_PROCCTL_H)
#    define _PTRACE(_x, _y) ptrace(_x, _y, NULL, 0)
#    define _PTRACE_DETACH(_x) ptrace(PT_DETACH, _x, (void *)1, 0)
#endif
 
#  ifdef HAVE_CAPABILITY_H
#    include <sys/capability.h>
#  endif
#endif
 
#ifdef HAVE_SANITIZER_LSAN_INTERFACE_H
#  include <sanitizer/lsan_interface.h>
#endif
 
#ifdef HAVE_SANITIZER_LSAN_INTERFACE_H
static int lsan_test_pipe[2] = {-1, -1};
static int lsan_test_pid = -1;
static int lsan_state = INT_MAX;
static bool lsan_disable = false;       //!< Explicitly disable LSAN
 
/*
 *      Some versions of lsan_interface.h are broken and don't declare
 *      the prototypes of the functions properly, omitting the zero argument
 *      specifier (void), so we need to disable the warning.
 *
 *      Observed with clang 5.
 */
DIAG_OFF(missing-prototypes)
/** Callback for LSAN - do not rename
 *
 */
char const CC_HINT(used) *__lsan_default_suppressions(void)
{
        return
                "leak:CRYPTO_THREAD_lock_new\n"         /* OpenSSL init leak - reported by heaptrack */
#if defined(__APPLE__)
                "leak:*gmtsub*\n"
                "leak:ImageLoaderMachO::doImageInit\n"
                "leak:_st_tzset_basic\n"
                "leak:attachCategories\n"
                "leak:fork\n"
                "leak:getaddrinfo\n"
                "leak:getpwuid_r\n"
                "leak:libSystem_atfork_child\n"
                "leak:libsystem_notify\n"
                "leak:load_images\n"
                "leak:newlocale\n"
                /* Perl >= 5.32.0 - Upstream bug, tracked by https://github.com/Perl/perl5/issues/18108 */
                "leak:perl_construct\n"
                "leak:realizeClassWithoutSwift\n"
                "leak:tzset\n"
                "leak:tzsetwall_basic\n"
#elif defined(__linux__)
                "leak:*getpwnam_r*\n"                   /* libc startup leak - reported by heaptrack */
                "leak:_dl_init\n"                       /* dl startup leak - reported by heaptrack */
                "leak:initgroups\n"                     /* libc startup leak - reported by heaptrack */
                "leak:kqueue\n"
#endif
                ;
}
 
/** Callback for LSAN - do not rename
 *
 * Turn off suppressions by default as it interferes with interpreting
 * output from some of the test utilities.
 */
char const CC_HINT(used) *__lsan_default_options(void)
{
        return "print_suppressions=0";
}
 
/** Callback for LSAN - do not rename
 *
 */
int CC_HINT(used) __lsan_is_turned_off(void)
{
        uint8_t ret = 1;
 
        /* Disable LSAN explicitly - Used for tests involving fork() */
        if (lsan_disable) return 1;
 
        /* Parent */
        if (lsan_test_pid != 0) return 0;
 
        /* Child */
        if (write(lsan_test_pipe[1], &ret, sizeof(ret)) < 0) {
                fprintf(stderr, "Writing LSAN status failed: %s", fr_syserror(errno));
        }
        close(lsan_test_pipe[1]);
        return 0;
}
DIAG_ON(missing-prototypes)
 
/** Determine if we're running under LSAN (Leak Sanitizer)
 *
 * @return
 *      - 0 if we're not.
 *      - 1 if we are.
 *      - -1 if we can't tell because of an error.
 *      - -2 if we can't tell because we were compiled with support for the LSAN interface.
 */
int fr_get_lsan_state(void)
{
        uint8_t ret = 0;
 
        if (lsan_state != INT_MAX) return lsan_state;/* Use cached result */
 
        if (pipe(lsan_test_pipe) < 0) {
                fr_strerror_printf("Failed opening internal pipe: %s", fr_syserror(errno));
                return -1;
        }
 
        lsan_test_pid = fork();
        if (lsan_test_pid == -1) {
                fr_strerror_printf("Error forking: %s", fr_syserror(errno));
                return -1;
        }
 
        /* Child */
        if (lsan_test_pid == 0) {
                close(lsan_test_pipe[0]);       /* Close parent's side */
                exit(EXIT_SUCCESS);             /* Results in LSAN calling __lsan_is_turned_off via onexit handler */
        }
 
        /* Parent */
        close(lsan_test_pipe[1]);               /* Close child's side */
 
        while ((read(lsan_test_pipe[0], &ret, sizeof(ret)) < 0) && (errno == EINTR));
 
        close(lsan_test_pipe[0]);               /* Close our side (so we don't leak FDs) */
 
        /* Collect child */
        waitpid(lsan_test_pid, NULL, 0);
 
        lsan_state = ret;                       /* Cache test results */
 
        return ret;
}
#else
int fr_get_lsan_state(void)
{
        fr_strerror_const("Not built with support for LSAN interface");
        return -2;
}
#endif
 
#if defined(HAVE_SYS_PROCCTL_H)
int fr_get_debug_state(void)
{
        int status;
 
        if (procctl(P_PID, getpid(), PROC_TRACE_STATUS, &status) == -1) {
                fr_strerror_printf("Cannot get dumpable flag: procctl(PROC_TRACE_STATUS) failed: %s", fr_syserror(errno));
                return DEBUGGER_STATE_UNKNOWN;
        }
 
        /*
         *      As FreeBSD docs say about "PROC_TRACE_STATUS":
         *
         *      Returns the current tracing status for the specified process in the
         *      integer variable pointed to by data.  If tracing is disabled, data
         *      is set to -1.  If tracing is enabled, but no debugger is attached by
         *      the ptrace(2) syscall, data is set to 0.  If a debugger is attached,
         *      data is set to the pid of the debugger process.
         */
        if (status <= 0) return DEBUGGER_STATE_NOT_ATTACHED;
 
        return DEBUGGER_STATE_ATTACHED;
}
#elif defined(__APPLE__)
/** The ptrace_attach() method no longer works as of macOS 11.4 (we always get eperm)
 *
 * Apple published this helpful article here which provides the
 * magical invocation: https://developer.apple.com/library/archive/qa/qa1361/_index.html
 *
 * @return
 *      - 0 if we're not.
 *      - 1 if we are.
 *      - -1
 */
int fr_get_debug_state(void)
{
        int                 ret;
        int                 mib[4];
        struct kinfo_proc   info;
        size_t              size;
 
        /*
         *      Initialize the flags so that, if sysctl fails for some
         *      reason, we get a predictable result.
         */
        info.kp_proc.p_flag = 0;
 
        /*
         *      Initialize mib, which tells sysctl the info we want, in this case
         *      we're looking for information about a specific process ID.
         */
        mib[0] = CTL_KERN;
        mib[1] = KERN_PROC;
        mib[2] = KERN_PROC_PID;
        mib[3] = getpid();
 
        /* Call sysctl */
        size = sizeof(info);
        ret = sysctl(mib, NUM_ELEMENTS(mib), &info, &size, NULL, 0);
        if (ret != 0) return -1;
 
        /* We're being debugged if the P_TRACED flag is set */
        return ((info.kp_proc.p_flag & P_TRACED) != 0);
}
#elif defined(HAVE_SYS_PTRACE_H) && !defined(__EMSCRIPTEN__)
/** Determine if we're running under a debugger by attempting to attach using pattach
 *
 * @return
 *      - 0 if we're not.
 *      - 1 if we are.
 *      - -1 if we can't tell because of an error.
 *      - -2 if we can't tell because we don't have the CAP_SYS_PTRACE capability.
 */
int fr_get_debug_state(void)
{
        int pid;
 
        int from_child[2] = {-1, -1};
 
#ifdef HAVE_CAPABILITY_H
        cap_flag_value_t        state;
        cap_t                   caps;
 
        /*
         *  If we're running under linux, we first need to check if we have
         *  permission to to ptrace. We do that using the capabilities
         *  functions.
         */
        caps = cap_get_proc();
        if (!caps) {
                fr_strerror_printf("Failed getting process capabilities: %s", fr_syserror(errno));
                return DEBUGGER_STATE_UNKNOWN;
        }
 
        if (cap_get_flag(caps, CAP_SYS_PTRACE, CAP_PERMITTED, &state) < 0) {
                fr_strerror_printf("Failed getting CAP_SYS_PTRACE permitted state: %s",
                                   fr_syserror(errno));
                cap_free(caps);
                return DEBUGGER_STATE_UNKNOWN;
        }
 
        if ((state == CAP_SET) && (cap_get_flag(caps, CAP_SYS_PTRACE, CAP_EFFECTIVE, &state) < 0)) {
                fr_strerror_printf("Failed getting CAP_SYS_PTRACE effective state: %s",
                                   fr_syserror(errno));
                cap_free(caps);
                return DEBUGGER_STATE_UNKNOWN;
        }
 
        /*
         *  We don't have permission to ptrace, so this test will always fail.
         */
        if (state == CAP_CLEAR) {
                fr_strerror_printf("ptrace capability not set.  If debugger detection is required run as root or: "
                                   "setcap cap_sys_ptrace+ep <path_to_binary>");
                cap_free(caps);
                return DEBUGGER_STATE_UNKNOWN_NO_PTRACE_CAP;
        }
        cap_free(caps);
#endif
 
        if (pipe(from_child) < 0) {
                fr_strerror_printf("Error opening internal pipe: %s", fr_syserror(errno));
                return DEBUGGER_STATE_UNKNOWN;
        }
 
        pid = fork();
        if (pid == -1) {
                fr_strerror_printf("Error forking: %s", fr_syserror(errno));
                return DEBUGGER_STATE_UNKNOWN;
        }
 
        /* Child */
        if (pid == 0) {
                int8_t  ret = DEBUGGER_STATE_NOT_ATTACHED;
                int     ppid = getppid();
                int     flags;
 
                /*
                 *      Disable the leak checker for this forked process
                 *      so we don't get spurious leaks reported.
                 */
#ifdef HAVE_SANITIZER_LSAN_INTERFACE_H
                lsan_disable = true;
#endif
 
DIAG_OFF(deprecated-declarations)
                flags = PT_ATTACH;
DIAG_ON(deprecated-declarations)
 
                /* Close parent's side */
                close(from_child[0]);
 
                /*
                 *      FreeBSD is extremely picky about the order of operations here
                 *      we need to attach, wait *then* write whilst the parent is still
                 *      suspended, then detach, continuing the process.
                 *
                 *      If we don't do it in that order the read in the parent triggers
                 *      a SIGKILL.
                 */
                errno = 0;
                _PTRACE(flags, ppid);
                if (errno == 0) {
                        /* Wait for the parent to stop */
                        waitpid(ppid, NULL, 0);
 
                        /* Tell the parent what happened */
                send_status:
                        if (write(from_child[1], &ret, sizeof(ret)) < 0) {
                                fprintf(stderr, "Writing ptrace status to parent failed: %s\n", fr_syserror(errno));
                        }
 
                        /* Detach */
                        _PTRACE_DETACH(ppid);
 
 
                        /*
                        *       We call _exit() instead of exit().  This means that we skip the atexit() handlers,
                        *       which don't need to run in a temporary child process.  Skipping them means that we
                        *       avoid dirtying those pages to "clean things up", which is then immediately followed by
                        *       exiting.
                        *
                        *       Skipping the atexit() handlers also means that we're not worried about memory leaks
                        *       because things "aren't cleaned up correctly".  We're not exiting cleanly here (and
                        *       don't care to exit cleanly).  So just exiting with no cleanups is fine.
                        */
                        _exit(0); /* don't run the atexit() handlers. */
                /*
                 *      man ptrace says the following:
                 *
                 *      EPERM  The specified process cannot be traced.  This could be
                 *      because the tracer has insufficient privileges (the
                 *      required capability is CAP_SYS_PTRACE); unprivileged
                 *      processes cannot trace processes that they cannot send
                 *      signals to or those running set-user-ID/set-group-ID
                 *      programs, for obvious reasons.  Alternatively, the process
                 *      may already be being traced, or (before Linux 2.6.26) be
                 *      init(1) (PID 1).
                 *
                 *      In any case, we are very unlikely to be able to attach to
                 *      the process from the panic action.
                 *
                 *      We checked for CAP_SYS_PTRACE previously, so know that
                 *      we _should_ haven been ablle to attach, so if we can't, it's
                 *      likely that we're already being traced.
                 */
                } else if (errno == EPERM) {
                        ret = DEBUGGER_STATE_ATTACHED;
                        goto send_status;
                }
 
                /*
                 *      Unexpected error, we don't know whether we're already running
                 *      under a debugger or not...
                 */
                ret = DEBUGGER_STATE_UNKNOWN;
                fprintf(stderr, "Debugger check failed to attach to parent with unexpected error: %s\n", fr_syserror(errno));
                goto send_status;
        /* Parent */
        } else {
                int8_t ret = DEBUGGER_STATE_UNKNOWN;
 
                /*
                 *      The child writes errno (reason) if pattach failed else 0.
                 *
                 *      This read may be interrupted by pattach,
                 *      which is why we need the loop.
                 */
                while ((read(from_child[0], &ret, sizeof(ret)) < 0) && (errno == EINTR));
 
                /* Close the pipes here (if we did it above, it might race with pattach) */
                close(from_child[1]);
                close(from_child[0]);
 
                /* Collect the status of the child */
                waitpid(pid, NULL, 0);
 
                return ret;
        }
}
#else
int fr_get_debug_state(void)
{
        fr_strerror_const("PTRACE not available");
 
        return DEBUGGER_STATE_UNKNOWN_NO_PTRACE;
}
#endif
 
/** Should be run before using setuid or setgid to get useful results
 *
 * @note sets the fr_debug_state global.
 */
void fr_debug_state_store(void)
{
        fr_debug_state = fr_get_debug_state();
 
#ifndef NDEBUG
        /*
         *  There are many reasons why this might happen with
         *  a vanilla install, so we don't want to spam users
         *  with messages they won't understand and may not
         *  want to resolve.
         */
        if (fr_debug_state < 0) fprintf(stderr, "Getting debug state failed: %s\n", fr_strerror());
#endif
}
 
/** Return current value of debug_state
 *
 * @param state to translate into a humanly readable value.
 * @return humanly readable version of debug state.
 */
char const *fr_debug_state_to_msg(fr_debug_state_t state)
{
        switch (state) {
        case DEBUGGER_STATE_UNKNOWN_NO_PTRACE:
                return "Debug state unknown (ptrace functionality not available)";
 
        case DEBUGGER_STATE_UNKNOWN_NO_PTRACE_CAP:
                return "Debug state unknown (cap_sys_ptrace capability not set)";
 
        case DEBUGGER_STATE_UNKNOWN:
                return "Debug state unknown";
 
        case DEBUGGER_STATE_ATTACHED:
                return "Found debugger attached";
 
        case DEBUGGER_STATE_NOT_ATTACHED:
                return "Debugger not attached";
        }
 
        return "<INVALID>";
}
 
/** Break in debugger (if were running under a debugger)
 *
 * If the server is running under a debugger this will raise a
 * SIGTRAP which will pause the running process.
 *
 * If the server is not running under debugger then this will do nothing.
 */
void fr_debug_break(bool always)
{
        if (always) raise(SIGTRAP);
 
        if (fr_debug_state < 0) fr_debug_state = fr_get_debug_state();
        if (fr_debug_state == DEBUGGER_STATE_ATTACHED) {
                fprintf(stderr, "Debugger detected, raising SIGTRAP\n");
                fflush(stderr);
 
                raise(SIGTRAP);
        }
}
 
static int _panic_on_free(UNUSED char *foo)
{
        fr_fault(SIGABRT);
        return -1;      /* this should make the free fail */
}
 
/** Insert memory into the context of another talloc memory chunk which
 * causes a panic when freed.
 *
 * @param ctx TALLOC_CTX to monitor for frees.
 */
void fr_panic_on_free(TALLOC_CTX *ctx)
{
        char *ptr;
 
        ptr = talloc(ctx, char);
        talloc_set_destructor(ptr, _panic_on_free);
}
 
/** Set the dumpable flag, also controls whether processes can PATTACH
 *
 * @param dumpable whether we should allow core dumping
 */
#if defined(HAVE_SYS_PRCTL_H) && defined(PR_SET_DUMPABLE) && !defined(__EMSCRIPTEN__)
static int fr_set_pr_dumpable_flag(bool dumpable)
{
        if (prctl(PR_SET_DUMPABLE, dumpable ? 1 : 0) < 0) {
                fr_strerror_printf("Cannot re-enable core dumps: prctl(PR_SET_DUMPABLE) failed: %s",
                                   fr_syserror(errno));
                return -1;
        }
 
        return 0;
}
#elif defined(HAVE_SYS_PROCCTL_H)
static int fr_set_pr_dumpable_flag(bool dumpable)
{
        int mode = dumpable ? PROC_TRACE_CTL_ENABLE : PROC_TRACE_CTL_DISABLE;
 
        if (procctl(P_PID, getpid(), PROC_TRACE_CTL, &mode) == -1) {
                fr_strerror_printf("Cannot re-enable core dumps: procctl(PROC_TRACE_CTL) failed: %s",
                                   fr_syserror(errno));
                return -1;
        }
 
        return 0;
}
#else
static int fr_set_pr_dumpable_flag(UNUSED bool dumpable)
{
        fr_strerror_const("Changing value of PR_DUMPABLE not supported on this system");
        return -2;
}
#endif
 
/** Get the processes dumpable flag
 *
 */
#if defined(HAVE_SYS_PRCTL_H) && defined(PR_GET_DUMPABLE) && !defined(__EMSCRIPTEN__)
static int fr_get_pr_dumpable_flag(void)
{
        int ret;
 
        ret = prctl(PR_GET_DUMPABLE);
        if (ret < 0) {
                fr_strerror_printf("Cannot get dumpable flag: %s", fr_syserror(errno));
                return -1;
        }
 
        /*
         *  Linux is crazy and prctl sometimes returns 2 for disabled
         */
        if (ret != 1) return 0;
        return 1;
}
#elif defined(HAVE_SYS_PROCCTL_H)
static int fr_get_pr_dumpable_flag(void)
{
        int status;
 
        if (procctl(P_PID, getpid(), PROC_TRACE_CTL, &status) == -1) {
                fr_strerror_printf("Cannot get dumpable flag: procctl(PROC_TRACE_CTL) failed: %s", fr_syserror(errno));
                return -1;
        }
 
        /*
         *      There are a few different kinds of disabled, but only
         *      one ENABLE.
         */
        if (status != PROC_TRACE_CTL_ENABLE) return 0;
 
        return 1;
}
#else
static int fr_get_pr_dumpable_flag(void)
{
        fr_strerror_const("Getting value of PR_DUMPABLE not supported on this system");
        return -2;
}
#endif
 
 
/** Get the current maximum for core files
 *
 * Do this before anything else so as to ensure it's properly initialized.
 */
int fr_set_dumpable_init(void)
{
#ifdef HAVE_SYS_RESOURCE_H
        if (getrlimit(RLIMIT_CORE, &init_core_limit) < 0) {
                fr_strerror_printf("Failed to get current core limit:  %s", fr_syserror(errno));
                return -1;
        }
#endif
        return 0;
}
 
/** Enable or disable core dumps
 *
 * @param allow_core_dumps whether to enable or disable core dumps.
 */
int fr_set_dumpable(bool allow_core_dumps)
{
        dump_core = allow_core_dumps;
 
#ifdef HAVE_SYS_RESOURCE_H
        {
                struct rlimit current;
 
                /*
                 *      Reset the core limits (or disable them)
                 */
                if (getrlimit(RLIMIT_CORE, &current) < 0) {
                        fr_strerror_printf("Failed to get current core limit:  %s", fr_syserror(errno));
                        return -1;
                }
 
                if (allow_core_dumps) {
                        if ((current.rlim_cur != init_core_limit.rlim_cur) ||
                            (current.rlim_max != init_core_limit.rlim_max)) {
                                if (setrlimit(RLIMIT_CORE, &init_core_limit) < 0) {
                                        fr_strerror_printf("Cannot update core dump limit: %s", fr_syserror(errno));
 
                                        return -1;
                                }
                        }
                /*
                 *      We've been told to disable core dumping,
                 *      rlim_cur is not set to zero.
                 *
                 *      Set rlim_cur to zero, but leave rlim_max
                 *      set to whatever the current value is.
                 *
                 *      This is because, later, we may need to
                 *      re-enable core dumps to allow the debugger
                 *      to attach *sigh*.
                 */
                } else if (current.rlim_cur != 0) {
                        struct rlimit no_core;
 
                        no_core.rlim_cur = 0;
                        no_core.rlim_max = current.rlim_max;
 
                        if (setrlimit(RLIMIT_CORE, &no_core) < 0) {
                                fr_strerror_printf("Failed disabling core dumps: %s", fr_syserror(errno));
 
                                return -1;
                        }
                }
        }
#endif
        /*
         *      Macro needed so we don't emit spurious errors
         */
#if defined(HAVE_SYS_PROCCTL_H) || (defined(HAVE_SYS_PRCTL_H) && defined(PR_SET_DUMPABLE))
        if (fr_set_pr_dumpable_flag(allow_core_dumps) < 0) return -1;
#endif
 
        return 0;
}
 
/** Reset dumpable state to previously configured value
 *
 * Needed after suid up/down
 *
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
int fr_reset_dumpable(void)
{
        return fr_set_dumpable(dump_core);
}
 
/** Check to see if panic_action file is world writable
 *
 * @return
 *      - 0 if file is OK.
 *      - -1 if the file is world writable.
 */
static int fr_fault_check_permissions(void)
{
        char const *p, *q;
        size_t len;
        char filename[256];
        struct stat statbuf;
 
        /*
         *      Try and guess which part of the command is the binary, and check to see if
         *      it's world writable, to try and save the admin from their own stupidity.
         *
         *      @fixme we should do this properly and take into account single and double
         *      quotes.
         */
        if ((q = strchr(panic_action, ' '))) {
                /*
                 *      need to use a static buffer, because allocing memory in a signal handler
                 *      is a bad idea and can result in deadlock.
                 */
                len = snprintf(filename, sizeof(filename), "%.*s", (int)(q - panic_action), panic_action);
                if (is_truncated(len, sizeof(filename))) {
                        fr_strerror_const("Failed writing panic_action to temporary buffer (truncated)");
                        return -1;
                }
                p = filename;
        } else {
                p = panic_action;
        }
 
        if (stat(p, &statbuf) == 0) {
#ifdef S_IWOTH
                if ((statbuf.st_mode & S_IWOTH) != 0) {
                        fr_strerror_printf("panic_action file \"%s\" is globally writable", p);
                        return -1;
                }
#endif
        }
 
        return 0;
}
 
/** Prints a simple backtrace (if execinfo is available) and calls panic_action if set.
 *
 * @param sig caught
 */
NEVER_RETURNS void fr_fault(int sig)
{
        char            cmd[sizeof(panic_action) + 20];
        char            *out = cmd;
        size_t          left = sizeof(cmd), ret;
 
        char const      *p = panic_action;
        char const      *q;
 
        int             code;
 
        /*
         *      If a debugger is attached, we don't want to run the panic action,
         *      as it may interfere with the operation of the debugger.
         *      If something calls us directly we just raise the signal and let
         *      the debugger handle it how it wants.
         */
        if (fr_debug_state == DEBUGGER_STATE_ATTACHED) {
                FR_FAULT_LOG("RAISING SIGNAL: %s", strsignal(sig));
                raise(sig);
        }
 
        /*
         *      Makes the backtraces slightly cleaner
         */
        memset(cmd, 0, sizeof(cmd));
 
        FR_FAULT_LOG("CAUGHT SIGNAL: %s", strsignal(sig));
 
        /*
         *      Run the callback if one was registered
         */
        if (panic_cb && (panic_cb(sig) < 0)) goto finish;
 
        fr_backtrace();
 
        /* No panic action set... */
        if (panic_action[0] == '\0') {
                FR_FAULT_LOG("No panic action set");
                goto finish;
        }
 
        /*
         *      Check for administrator sanity.
         */
        if (fr_fault_check_permissions() < 0) {
                FR_FAULT_LOG("Refusing to execute panic action: %s", fr_strerror());
                goto finish;
        }
 
        /* Substitute %p for the current PID (useful for attaching a debugger) */
        while ((q = strstr(p, "%p"))) {
                out += ret = snprintf(out, left, "%.*s%d", (int) (q - p), p, (int) getpid());
                if (left <= ret) {
                oob:
                        FR_FAULT_LOG("Panic action too long");
                        fr_exit_now(128 + sig);
                }
                left -= ret;
                p = q + 2;
        }
        if (strlen(p) >= left) goto oob;
        strlcpy(out, p, left);
 
        {
                bool disable = false;
 
                FR_FAULT_LOG("Calling: %s", cmd);
 
                /*
                 *      Here we temporarily enable the dumpable flag so if GBD or LLDB
                 *      is called in the panic_action, they can pattach to the running
                 *      process.
                 */
                if (fr_get_pr_dumpable_flag() == 0) {
                        if ((fr_set_pr_dumpable_flag(true) < 0) || !fr_get_pr_dumpable_flag()) {
                                FR_FAULT_LOG("Failed setting dumpable flag, pattach may not work: %s", fr_strerror());
                        } else {
                                disable = true;
                        }
                        FR_FAULT_LOG("Temporarily setting PR_DUMPABLE to 1");
                }
 
                code = system(cmd);
 
                /*
                 *      We only want to error out here, if dumpable was originally disabled
                 *      and we managed to change the value to enabled, but failed
                 *      setting it back to disabled.
                 */
                if (disable) {
                        FR_FAULT_LOG("Resetting PR_DUMPABLE to 0");
                        if (fr_set_pr_dumpable_flag(false) < 0) {
                                FR_FAULT_LOG("Failed resetting dumpable flag to off: %s", fr_strerror());
                                FR_FAULT_LOG("Exiting due to insecure process state");
                                fr_exit_now(EXIT_FAILURE);
                        }
                }
 
                FR_FAULT_LOG("Panic action exited with %i", code);
 
                fr_exit_now(128 + sig);
        }
 
finish:
        /*
         *      (Re-)Raise the signal, so that if we're running under
         *      a debugger.
         *
         *      This allows debuggers to function normally and catch
         *      fatal signals.
         */
        fr_unset_signal(sig);           /* Make sure we don't get into a loop */
        raise(sig);
        fr_exit_now(128 + sig);         /* Function marked as noreturn */
}
 
/** Callback executed on fatal talloc error
 *
 * This is the simple version which mostly behaves the same way as the default
 * one, and will not call panic_action.
 *
 * @param reason string provided by talloc.
 */
static void _fr_talloc_fault_simple(char const *reason) CC_HINT(noreturn);
static void _fr_talloc_fault_simple(char const *reason)
{
        FR_FAULT_LOG("talloc abort: %s\n", reason);
 
        fr_backtrace();
        abort();
}
 
/** Callback executed on fatal talloc error
 *
 * Translates a talloc abort into a fr_fault call.
 * Mostly to work around issues with some debuggers not being able to
 * attach after a SIGABRT has been raised.
 *
 * @param reason string provided by talloc.
 */
static void _fr_talloc_fault(char const *reason) CC_HINT(noreturn);
static void _fr_talloc_fault(char const *reason)
{
        FR_FAULT_LOG("talloc abort: %s", reason);
#ifdef SIGABRT
        fr_fault(SIGABRT);
#endif
        fr_exit_now(128 + SIGABRT);
}
 
/** Wrapper to pass talloc log output to our fr_fault_log function
 *
 */
static void _fr_talloc_log(char const *msg)
{
        fr_fault_log("%s\n", msg);
}
 
/** Generate a talloc memory report for a context and print to stderr/stdout
 *
 * @param ctx to generate a report for, may be NULL in which case the root context is used.
 */
int fr_log_talloc_report(TALLOC_CTX const *ctx)
{
#define TALLOC_REPORT_MAX_DEPTH 20
 
        FILE    *log;
        int     fd;
 
        fd = dup(fr_fault_log_fd);
        if (fd < 0) {
                fr_strerror_printf("Couldn't write memory report, failed to dup log fd: %s", fr_syserror(errno));
                return -1;
        }
        log = fdopen(fd, "w");
        if (!log) {
                close(fd);
                fr_strerror_printf("Couldn't write memory report, fdopen failed: %s", fr_syserror(errno));
                return -1;
        }
 
        if (!ctx) {
                fprintf(log, "Current state of talloced memory:\n");
                talloc_report_full(talloc_null_ctx(), log);
        } else {
                int i;
 
                fprintf(log, "Talloc chunk lineage:\n");
                fprintf(log, "%p (%s)", ctx, talloc_get_name(ctx));
 
                i = 0;
                while ((i < TALLOC_REPORT_MAX_DEPTH) && (ctx = talloc_parent(ctx))) {
                        fprintf(log, " < %p (%s)", ctx, talloc_get_name(ctx));
                        i++;
                }
                fprintf(log, "\n");
 
                i = 0;
                do {
                        fprintf(log, "Talloc context level %i:\n", i++);
                        talloc_report_full(ctx, log);
                } while ((ctx = talloc_parent(ctx)) &&
                         (i < TALLOC_REPORT_MAX_DEPTH) &&
                         (talloc_parent(ctx) != talloc_autofree_ctx) && /* Stop before we hit the autofree ctx */
                         (talloc_parent(ctx) != talloc_null_ctx()));    /* Stop before we hit NULL ctx */
        }
 
        fclose(log);
 
        return 0;
}
 
static int _disable_null_tracking(UNUSED bool *p)
{
        talloc_disable_null_tracking();
        return 0;
}
 
/** Disable the null tracking context when a talloc chunk is freed
 *
 */
void fr_disable_null_tracking_on_free(TALLOC_CTX *ctx)
{
        bool *marker;
 
        /*
         *  Disable null tracking on exit, else valgrind complains
         */
        marker = talloc(ctx, bool);
        talloc_set_destructor(marker, _disable_null_tracking);
}
 
/** Register talloc fault handlers
 *
 * Just register the fault handlers we need to make talloc
 * produce useful debugging output.
 */
void fr_talloc_fault_setup(void)
{
        talloc_set_log_fn(_fr_talloc_log);
        talloc_set_abort_fn(_fr_talloc_fault_simple);
}
 
/** Registers signal handlers to execute panic_action on fatal signal
 *
 * May be called multiple time to change the panic_action/program.
 *
 * @param[in] ctx       to allocate autofreeable resources in.
 * @param[in] cmd       to execute on fault. If present %p will be substituted
 *                      for the parent PID before the command is executed, and %e
 *                      will be substituted for the currently running program.
 * @param program Name of program currently executing (argv[0]).
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
int fr_fault_setup(TALLOC_CTX *ctx, char const *cmd, char const *program)
{
        static bool setup = false;
 
        char *out = panic_action;
        size_t left = sizeof(panic_action);
 
        char const *p = cmd;
        char const *q;
 
        if (cmd) {
                size_t ret;
 
                /* Substitute %e for the current program */
                while ((q = strstr(p, "%e"))) {
                        out += ret = snprintf(out, left, "%.*s%s", (int) (q - p), p, program ? program : "");
                        if (left <= ret) {
                        oob:
                                fr_strerror_const("Panic action too long");
                                return -1;
                        }
                        left -= ret;
                        p = q + 2;
                }
                if (strlen(p) >= left) goto oob;
                strlcpy(out, p, left);
        } else {
                *panic_action = '\0';
        }
 
        /*
         *      Check for administrator sanity.
         */
        if (fr_fault_check_permissions() < 0) return -1;
 
        /* Unsure what the side effects of changing the signal handler mid execution might be */
        if (!setup) {
                char                    *env;
 
                /*
                 *  Installing signal handlers interferes with some debugging
                 *  operations.  Give the developer control over whether the
                 *  signal handlers are installed or not.
                 */
                env = getenv("DEBUGGER_ATTACHED");
                if (env && (strcmp(env, "yes") == 0)) {
                        fr_debug_state = DEBUGGER_STATE_ATTACHED;               /* i.e. disable signal handlers */
 
                } else if (env && (strcmp(env, "no") == 0)) {
                        fr_debug_state = DEBUGGER_STATE_NOT_ATTACHED;   /* i.e. enable signal handlers */
 
                        /*
                         *  Figure out if we were started under a debugger
                         */
                } else {
                        if (fr_debug_state < 0) fr_debug_state = fr_get_debug_state();
                }
 
                talloc_set_log_fn(_fr_talloc_log);
 
                /*
                 *  These signals can't be properly dealt with in the debugger
                 *  if we set our own signal handlers.
                 */
                switch (fr_debug_state) {
                default:
                case DEBUGGER_STATE_NOT_ATTACHED:
#ifdef SIGABRT
                        if (fr_set_signal(SIGABRT, fr_fault) < 0) return -1;
 
                        /*
                         *  Use this instead of abort so we get a
                         *  full backtrace with broken versions of LLDB
                         */
                        talloc_set_abort_fn(_fr_talloc_fault);
#endif
#ifdef SIGILL
                        if (fr_set_signal(SIGILL, fr_fault) < 0) return -1;
#endif
#ifdef SIGFPE
                        if (fr_set_signal(SIGFPE, fr_fault) < 0) return -1;
#endif
#ifdef SIGSEGV
                        if (fr_set_signal(SIGSEGV, fr_fault) < 0) return -1;
#endif
#ifdef SIGALRM
                        /*
                         *  This is used be jlibtool to terminate
                         *  processes which have been running too
                         *  long.
                         */
                        if (fr_set_signal(SIGALRM, fr_fault) < 0) return -1;
#endif
                        break;
 
                case DEBUGGER_STATE_ATTACHED:
                        break;
                }
 
                /*
                 *  Needed for memory reports
                 */
                fr_disable_null_tracking_on_free(ctx);
 
#if defined(HAVE_MALLOPT) && !defined(NDEBUG)
                /*
                 *  If were using glibc malloc > 2.4 this scribbles over
                 *  uninitialised and freed memory, to make memory issues easier
                 *  to track down.
                 */
#  ifdef M_PERTURB
                if (!getenv("TALLOC_FREE_FILL")) mallopt(M_PERTURB, 0x42);
#  endif
#  ifdef M_CHECK_ACTION
                mallopt(M_CHECK_ACTION, 3);
#  endif
#endif
                fr_backtrace_init(program);
        }
        setup = true;
 
        return 0;
}
 
/** Set a callback to be called before fr_fault()
 *
 * @param func to execute. If callback returns < 0
 *      fr_fault will exit before running panic_action code.
 */
void fr_fault_set_cb(fr_fault_cb_t func)
{
        panic_cb = func;
}
 
/** Log output to the fr_fault_log_fd
 *
 * We used to support a user defined callback, which was set to a radlog
 * function. Unfortunately, when logging to syslog, syslog would alloc memory
 * which would result in a deadlock if fr_fault was triggered from within
 * a allocation call.
 *
 * Now we just write directly to the FD.
 */
void fr_fault_log(char const *msg, ...)
{
        va_list ap;
 
        if (fr_fault_log_fd < 0) return;
 
        va_start(ap, msg);
        vdprintf(fr_fault_log_fd, msg, ap);
        va_end(ap);
}
 
/** Print data as a hex block
 *
 */
void fr_fault_log_hex(uint8_t const *data, size_t data_len)
{
        size_t          i, j, len;
        char            buffer[(0x10 * 3) + 1];
        char            *p, *end = buffer + sizeof(buffer);
 
        for (i = 0; i < data_len; i += 0x10) {
                len = 0x10;
                if ((i + len) > data_len) len = data_len - i;
 
                for (p = buffer, j = 0; j < len; j++, p += 3) snprintf(p, end - p, "%02x ", data[i + j]);
 
                dprintf(fr_fault_log_fd, "%04x: %s\n", (unsigned int) i, buffer);
        }
}
 
/** Set a file descriptor to log memory reports to.
 *
 * @param fd to write output to.
 */
void fr_fault_set_log_fd(int fd)
{
        fr_fault_log_fd = fd;
}
 
/** A soft assertion which triggers the fault handler in debug builds
 *
 * @param[in] file      the assertion failed in.
 * @param[in] line      of the assertion in the file.
 * @param[in] expr      that was evaluated.
 * @param[in] msg       Message to print (may be NULL).
 * @param[in] ...       Arguments for msg string.
 * @return the value of cond.
 */
bool _fr_assert_fail(char const *file, int line, char const *expr, char const *msg, ...)
{
        if (msg) {
                char str[256];          /* Decent compilers won't allocate this unless fmt is !NULL... */
                va_list ap;
 
                va_start(ap, msg);
                (void)vsnprintf(str, sizeof(str), msg, ap);
                va_end(ap);
 
#ifndef NDEBUG
                FR_FAULT_LOG("ASSERT FAILED %s[%d]: %s: %s", file, line, expr, str);
                fr_fault(SIGABRT);
#else
                FR_FAULT_LOG("ASSERT WOULD FAIL %s[%d]: %s: %s", file, line, expr, str);
                return false;
#endif
        }
 
#ifndef NDEBUG
        FR_FAULT_LOG("ASSERT FAILED %s[%d]: %s", file, line, expr);
        fr_fault(SIGABRT);
#else
        FR_FAULT_LOG("ASSERT WOULD FAIL %s[%d]: %s", file, line, expr);
        return false;
#endif
}
 
/** A fatal assertion which triggers the fault handler in debug builds or exits
 *
 * @param[in] file      the assertion failed in.
 * @param[in] line      of the assertion in the file.
 * @param[in] expr      that was evaluated.
 * @param[in] msg       Message to print (may be NULL).
 * @param[in] ...       Arguments for msg string.
 */
void _fr_assert_fatal(char const *file, int line, char const *expr, char const *msg, ...)
{
        if (msg) {
                char str[256];          /* Decent compilers won't allocate this unless fmt is !NULL... */
                va_list ap;
 
                va_start(ap, msg);
                (void)vsnprintf(str, sizeof(str), msg, ap);
                va_end(ap);
 
                FR_FAULT_LOG("FATAL ASSERT %s[%d]: %s: %s", file, line, expr, str);
        } else {
                FR_FAULT_LOG("FATAL ASSERT %s[%d]: %s", file, line, expr);
        }
 
#ifdef NDEBUG
        _fr_exit(file, line, 128 + SIGABRT, true);
#else
        fr_fault(SIGABRT);
#endif
}
 
/** Exit possibly printing a message about why we're exiting.
 *
 * @note Use the fr_exit(status) macro instead of calling this function directly.
 *
 * @param[in] file      where fr_exit() was called.
 * @param[in] line      where fr_exit() was called.
 * @param[in] status    we're exiting with.
 * @param[in] now       Exit immediately.
 */
#ifndef NDEBUG
NEVER_RETURNS void _fr_exit(char const *file, int line, int status, bool now)
{
        if (status != EXIT_SUCCESS) {
                char const *error = fr_strerror();
 
                if (error && *error && (status != 0)) {
                        FR_FAULT_LOG("%sEXIT(%i) CALLED %s[%d].  Last error was: %s", now ? "_" : "",
                                     status, file, line, error);
                } else {
                        FR_FAULT_LOG("%sEXIT(%i) CALLED %s[%d]", now ? "_" : "", status, file, line);
                }
 
                fr_debug_break(false);  /* If running under GDB we'll break here */
        }
 
        if (now) _Exit(status);
        exit(status);
}
#else
NEVER_RETURNS void _fr_exit(UNUSED char const *file, UNUSED int line, int status, bool now)
{
        if (status != EXIT_SUCCESS) fr_debug_break(false);      /* If running under GDB we'll break here */
 
        if (now) _Exit(status);
        exit(status);
}
#endif
 
/*
 *      Sign a structure, but skip _signature at "offset".
 */
static uint32_t fr_hash_struct(void const *ptr, size_t size, size_t offset)
{
        uint32_t hash;
 
        /*
         *      Hash entry is at the end of the structure, that's
         *      best...
         */
        if ((size + 4) == offset) {
                return fr_hash(ptr, size);
        }
 
        hash = fr_hash(ptr, offset);
        return fr_hash_update(((uint8_t const *) ptr) + offset + 4, size - (offset + 4), hash);
}
 
void fr_sign_struct(void *ptr, size_t size, size_t offset)
{
        *(uint32_t *) (((uint8_t *) ptr) + offset) = fr_hash_struct(ptr, size, offset);
}
 
void fr_verify_struct(void const *ptr, size_t size, size_t offset)
{
        uint32_t hash;
 
        hash = fr_hash_struct(ptr, size, offset);
 
        (void) fr_cond_assert(hash == *(uint32_t const *) (((uint8_t const *) ptr) + offset));
}
 
void fr_verify_struct_member(void const *ptr, size_t len, uint32_t *signature)
{
        uint32_t hash;
 
        hash = fr_hash(ptr, len);
        (void) fr_cond_assert(hash == *signature);
}