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Diffstat (limited to 'src/lib/debug.c')
| -rw-r--r-- | src/lib/debug.c | 1217 |
1 files changed, 1217 insertions, 0 deletions
diff --git a/src/lib/debug.c b/src/lib/debug.c new file mode 100644 index 0000000..b000903 --- /dev/null +++ b/src/lib/debug.c @@ -0,0 +1,1217 @@ +/* + * 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 + */ + +/** + * @file debug.c + * @brief Various functions to aid in debugging + * + * @copyright 2013 The FreeRADIUS server project + * @copyright 2013 Arran Cudbard-Bell <a.cudbardb@freeradius.org> + */ +#include <assert.h> +#include <freeradius-devel/libradius.h> +#include <sys/stat.h> +#include <sys/wait.h> + +USES_APPLE_DEPRECATED_API + +#if defined(HAVE_MALLOPT) && defined(HAVE_MALLOC_H) +# include <malloc.h> +#endif + +/* + * runtime backtrace functions are not POSIX but are included in + * glibc, OSX >= 10.5 and various BSDs + */ +#ifdef HAVE_EXECINFO +# include <execinfo.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 HAVE_PTHREAD_H +# define PTHREAD_MUTEX_LOCK pthread_mutex_lock +# define PTHREAD_MUTEX_UNLOCK pthread_mutex_unlock +#else +# define PTHREAD_MUTEX_LOCK(_x) +# define PTHREAD_MUTEX_UNLOCK(_x) +#endif + +#ifdef HAVE_EXECINFO +# ifndef MAX_BT_FRAMES +# define MAX_BT_FRAMES 128 +# endif +# ifndef MAX_BT_CBUFF +# define MAX_BT_CBUFF 1048576 //!< Should be a power of 2 +# endif + +# ifdef HAVE_PTHREAD_H +static pthread_mutex_t fr_debug_init = PTHREAD_MUTEX_INITIALIZER; +# endif + +typedef struct fr_bt_info { + void *obj; //!< Memory address of the block of allocated memory. + void *frames[MAX_BT_FRAMES]; //!< Backtrace frame data + int count; //!< Number of frames stored +} fr_bt_info_t; + +struct fr_bt_marker { + void *obj; //!< Pointer to the parent object, this is our needle + //!< when we iterate over the contents of the circular buffer. + fr_cbuff_t *cbuff; //!< Where we temporarily store the backtraces +}; +#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. + +static int fr_fault_log_fd = STDERR_FILENO; //!< Where to write debug output. + +fr_debug_state_t fr_debug_state = DEBUG_STATE_UNKNOWN; //!< Whether we're attached to by a debugger. + +#ifdef HAVE_SYS_RESOURCE_H +static struct rlimit core_limits; +#endif + +static TALLOC_CTX *talloc_null_ctx; +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. + */ +#ifdef 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) +# else +# 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 + +/** 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. + */ +static int fr_get_debug_state(void) +{ + int pid; + + int from_child[2] = {-1, -1}; + +#ifdef HAVE_CAPABILITY_H + cap_flag_value_t value; + cap_t current; + + /* + * 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. + */ + current = cap_get_proc(); + if (!current) { + fr_strerror_printf("Failed getting process capabilities: %s", fr_syserror(errno)); + return DEBUG_STATE_UNKNOWN; + } + + if (cap_get_flag(current, CAP_SYS_PTRACE, CAP_PERMITTED, &value) < 0) { + fr_strerror_printf("Failed getting permitted ptrace capability state: %s", + fr_syserror(errno)); + cap_free(current); + return DEBUG_STATE_UNKNOWN; + } + + if ((value == CAP_SET) && (cap_get_flag(current, CAP_SYS_PTRACE, CAP_EFFECTIVE, &value) < 0)) { + fr_strerror_printf("Failed getting effective ptrace capability state: %s", + fr_syserror(errno)); + cap_free(current); + return DEBUG_STATE_UNKNOWN; + } + + /* + * We don't have permission to ptrace, so this test will always fail. + */ + if (value == 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_radiusd>"); + cap_free(current); + return DEBUG_STATE_UNKNOWN_NO_PTRACE_CAP; + } + cap_free(current); +#endif + + if (pipe(from_child) < 0) { + fr_strerror_printf("Error opening internal pipe: %s", fr_syserror(errno)); + return DEBUG_STATE_UNKNOWN; + } + + pid = fork(); + if (pid == -1) { + fr_strerror_printf("Error forking: %s", fr_syserror(errno)); + return DEBUG_STATE_UNKNOWN; + } + + /* Child */ + if (pid == 0) { + int8_t ret = DEBUG_STATE_NOT_ATTACHED; + int ppid = getppid(); + + /* 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. + */ + if (_PTRACE(PT_ATTACH, ppid) == 0) { + /* Wait for the parent to stop */ + waitpid(ppid, NULL, 0); + + /* Tell the parent what happened */ + if (write(from_child[1], &ret, sizeof(ret)) < 0) { + fprintf(stderr, "Writing ptrace status to parent failed: %s", fr_syserror(errno)); + } + + /* Detach */ + _PTRACE_DETACH(ppid); + exit(0); + } + + ret = DEBUG_STATE_ATTACHED; + /* Tell the parent what happened */ + if (write(from_child[1], &ret, sizeof(ret)) < 0) { + fprintf(stderr, "Writing ptrace status to parent failed: %s", fr_syserror(errno)); + } + + exit(0); + /* Parent */ + } else { + int8_t ret = DEBUG_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; + } +} +#elif defined(HAVE_SYS_PROCCTL_H) +static 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 DEBUG_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 DEBUG_STATE_NOT_ATTACHED; + + return DEBUG_STATE_ATTACHED; +} +#else +static int fr_get_debug_state(void) +{ + fr_strerror_printf("PTRACE not available"); + + return DEBUG_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_store_debug_state(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 DEBUG_STATE_UNKNOWN_NO_PTRACE: + return "Debug state unknown (ptrace functionality not available)"; + + case DEBUG_STATE_UNKNOWN_NO_PTRACE_CAP: + return "Debug state unknown (cap_sys_ptrace capability not set)"; + + case DEBUG_STATE_UNKNOWN: + return "Debug state unknown"; + + case DEBUG_STATE_ATTACHED: + return "Found debugger attached"; + + case DEBUG_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 == DEBUG_STATE_ATTACHED) { + fprintf(stderr, "Debugger detected, raising SIGTRAP\n"); + fflush(stderr); + + raise(SIGTRAP); + } +} + +#ifdef HAVE_EXECINFO +/** Print backtrace entry for a given object + * + * @param cbuff to search in. + * @param obj pointer to original object + */ +void backtrace_print(fr_cbuff_t *cbuff, void *obj) +{ + fr_bt_info_t *p; + bool found = false; + + while ((p = fr_cbuff_rp_next(cbuff, NULL))) { + if ((p->obj == obj) || !obj) { + found = true; + + fprintf(stderr, "Stacktrace for: %p\n", p->obj); + backtrace_symbols_fd(p->frames, p->count, STDERR_FILENO); + } + }; + + if (!found) { + fprintf(stderr, "No backtrace available for %p", obj); + } +} + +/** Generate a backtrace for an object + * + * If this is the first entry being inserted + */ +int fr_backtrace_do(fr_bt_marker_t *marker) +{ + fr_bt_info_t *bt; + + if (!fr_assert(marker->obj) || !fr_assert(marker->cbuff)) return -1; + + bt = talloc_zero(NULL, fr_bt_info_t); + if (!bt) return -1; + + bt->obj = marker->obj; + bt->count = backtrace(bt->frames, MAX_BT_FRAMES); + + fr_cbuff_rp_insert(marker->cbuff, bt); + + return 0; +} + +/** Inserts a backtrace marker into the provided context + * + * Allows for maximum laziness and will initialise a circular buffer if one has not already been created. + * + * Code augmentation should look something like: +@verbatim + // Create a static cbuffer pointer, the first call to backtrace_attach will initialise it + static fr_cbuff_t *my_obj_bt; + + my_obj_t *alloc_my_obj(TALLOC_CTX *ctx) { + my_obj_t *this; + + this = talloc(ctx, my_obj_t); + + // Attach backtrace marker to object + backtrace_attach(&my_obj_bt, this); + + return this; + } +@endverbatim + * + * Then, later when a double free occurs: +@verbatim + (gdb) call backtrace_print(&my_obj_bt, <pointer to double freed memory>) +@endverbatim + * + * which should print a limited backtrace to stderr. Note, this backtrace will not include any argument + * values, but should at least show the code path taken. + * + * @param cbuff this should be a pointer to a static *fr_cbuff. + * @param obj we want to generate a backtrace for. + */ +fr_bt_marker_t *fr_backtrace_attach(fr_cbuff_t **cbuff, TALLOC_CTX *obj) +{ + fr_bt_marker_t *marker; + + if (*cbuff == NULL) { + PTHREAD_MUTEX_LOCK(&fr_debug_init); + /* Check again now we hold the mutex - eww*/ + if (*cbuff == NULL) *cbuff = fr_cbuff_alloc(NULL, MAX_BT_CBUFF, true); + PTHREAD_MUTEX_UNLOCK(&fr_debug_init); + } + + marker = talloc(obj, fr_bt_marker_t); + if (!marker) { + return NULL; + } + + marker->obj = (void *) obj; + marker->cbuff = *cbuff; + + fprintf(stderr, "Backtrace attached to %s %p\n", talloc_get_name(obj), obj); + /* + * Generate the backtrace for memory allocation + */ + fr_backtrace_do(marker); + talloc_set_destructor(marker, fr_backtrace_do); + + return marker; +} +#else +void backtrace_print(UNUSED fr_cbuff_t *cbuff, UNUSED void *obj) +{ + fprintf(stderr, "Server built without fr_backtrace_* support, requires execinfo.h and possibly -lexecinfo\n"); +} +fr_bt_marker_t *fr_backtrace_attach(UNUSED fr_cbuff_t **cbuff, UNUSED TALLOC_CTX *obj) +{ + fprintf(stderr, "Server built without fr_backtrace_* support, requires execinfo.h and possibly -lexecinfo\n"); + abort(); +} +#endif /* ifdef HAVE_EXECINFO */ + +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) +static int fr_set_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_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_dumpable_flag(UNUSED bool dumpable) +{ + fr_strerror_printf("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) +static int fr_get_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_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_dumpable_flag(void) +{ + fr_strerror_printf("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, &core_limits) < 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; + /* + * If configured, turn core dumps off. + */ + if (!allow_core_dumps) { +#ifdef HAVE_SYS_RESOURCE_H + struct rlimit no_core; + + no_core.rlim_cur = 0; + no_core.rlim_max = core_limits.rlim_max; + + if (setrlimit(RLIMIT_CORE, &no_core) < 0) { + fr_strerror_printf("Failed disabling core dumps: %s", fr_syserror(errno)); + + return -1; + } +#endif + return 0; + } + + if (fr_set_dumpable_flag(true) < 0) return -1; + + /* + * Reset the core dump limits to their original value. + */ +#ifdef HAVE_SYS_RESOURCE_H + if (setrlimit(RLIMIT_CORE, &core_limits) < 0) { + fr_strerror_printf("Cannot update core dump limit: %s", fr_syserror(errno)); + + return -1; + } +#endif + return 0; +} + +/** Reset dumpable state to previously configured value + * + * Needed after suid up/down + * + * @return 0 on success, else -1 on failure. + */ +int fr_reset_dumpable(void) +{ + return fr_set_dumpable(dump_core); +} + +/** Check to see if panic_action file is world writeable + * + * @return 0 if file is OK, else -1. + */ +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 writeable, 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 mallocing 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_printf("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 == DEBUG_STATE_ATTACHED) { + FR_FAULT_LOG("RAISING SIGNAL: %s", strsignal(sig)); + raise(sig); + goto finish; + } + + /* + * Makes the backtraces slightly cleaner + */ + memset(cmd, 0, sizeof(cmd)); + + FR_FAULT_LOG("CAUGHT SIGNAL: %s", strsignal(sig)); + + /* + * Check for administrator sanity. + */ + if (fr_fault_check_permissions() < 0) { + FR_FAULT_LOG("Refusing to execute panic action: %s", fr_strerror()); + goto finish; + } + + /* + * Run the callback if one was registered + */ + if (panic_cb && (panic_cb(sig) < 0)) goto finish; + + /* + * Produce a simple backtrace - They're very basic but at least give us an + * idea of the area of the code we hit the issue in. + * + * See below in fr_fault_setup() and + * https://sourceware.org/bugzilla/show_bug.cgi?id=16159 + * for why we only print backtraces in debug builds if we're using GLIBC. + */ +#if defined(HAVE_EXECINFO) && (!defined(NDEBUG) || !defined(__GNUC__)) + if (fr_fault_log_fd >= 0) { + size_t frame_count; + void *stack[MAX_BT_FRAMES]; + + frame_count = backtrace(stack, MAX_BT_FRAMES); + + FR_FAULT_LOG("Backtrace of last %zu frames:", frame_count); + + backtrace_symbols_fd(stack, frame_count, fr_fault_log_fd); + } +#endif + + /* No panic action set... */ + if (panic_action[0] == '\0') { + FR_FAULT_LOG("No panic action set"); + 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(1); + } + 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_dumpable_flag() == 0) { + if ((fr_set_dumpable_flag(true) < 0) || !fr_get_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_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(1); + } + } + + FR_FAULT_LOG("Panic action exited with %i", code); + + fr_exit_now(code); + } + + +finish: + /* + * (Re-)Raise the signal, so that if we're running under + * a debugger, the debugger can break when it receives + * the signal. + */ + fr_unset_signal(sig); /* Make sure we don't get into a loop */ + + raise(sig); + + fr_exit_now(1); /* 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); + +#if defined(HAVE_EXECINFO) && (!defined(NDEBUG) || !defined(__GNUC__)) + if (fr_fault_log_fd >= 0) { + size_t frame_count; + void *stack[MAX_BT_FRAMES]; + + frame_count = backtrace(stack, MAX_BT_FRAMES); + FR_FAULT_LOG("Backtrace of last %zu frames:", frame_count); + backtrace_symbols_fd(stack, frame_count, fr_fault_log_fd); + } +#endif + 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(1); +} + +/** 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 *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 _fr_disable_null_tracking(UNUSED bool *p) +{ + talloc_disable_null_tracking(); + return 0; +} + +/** 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 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. + */ +DIAG_OFF(deprecated-declarations) +int fr_fault_setup(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_printf("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; + fr_debug_state_t debug_state; + + /* + * Installing signal handlers interferes with some debugging + * operations. Give the developer control over whether the + * signal handlers are installed or not. + */ + env = getenv("DEBUG"); + if (!env || (strcmp(env, "no") == 0)) { + debug_state = DEBUG_STATE_NOT_ATTACHED; + } else if (!strcmp(env, "auto") || !strcmp(env, "yes")) { + /* + * Figure out if we were started under a debugger + */ + if (fr_debug_state < 0) fr_debug_state = fr_get_debug_state(); + debug_state = fr_debug_state; + } else { + debug_state = DEBUG_STATE_ATTACHED; + } + + 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 (debug_state) { + default: +#ifndef NDEBUG + FR_FAULT_LOG("Debugger check failed: %s", fr_strerror()); + FR_FAULT_LOG("Signal processing in debuggers may not work as expected"); +#endif + /* FALL-THROUGH */ + + case DEBUG_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 + break; + + case DEBUG_STATE_ATTACHED: + break; + } + + /* + * Needed for memory reports + */ + { + TALLOC_CTX *tmp; + bool *marker; + + tmp = talloc(NULL, bool); + talloc_null_ctx = talloc_parent(tmp); + talloc_free(tmp); + + /* + * Disable null tracking on exit, else valgrind complains + */ + talloc_autofree_ctx = talloc_autofree_context(); + marker = talloc(talloc_autofree_ctx, bool); + talloc_set_destructor(marker, _fr_disable_null_tracking); + } + +#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. + */ + if (!getenv("TALLOC_FREE_FILL")) mallopt(M_PERTURB, 0x42); + mallopt(M_CHECK_ACTION, 3); +#endif + +#if defined(HAVE_EXECINFO) && defined(__GNUC__) && !defined(NDEBUG) + /* + * We need to pre-load lgcc_s, else we can get into a deadlock + * in fr_fault, as backtrace() attempts to dlopen it. + * + * Apparently there's a performance impact of loading lgcc_s, + * so only do it if this is a debug build. + * + * See: https://sourceware.org/bugzilla/show_bug.cgi?id=16159 + */ + { + void *stack[10]; + + backtrace(stack, 10); + } +#endif + } + setup = true; + + return 0; +} +DIAG_ON(deprecated-declarations) + +/** 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 malloc memory + * which would result in a deadlock if fr_fault was triggered from within + * a malloc 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); +} + +/** 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 file the assertion failed in. + * @param line of the assertion in the file. + * @param expr that was evaluated. + * @param cond Result of evaluating the expression. + * @return the value of cond. + */ +bool fr_assert_cond(char const *file, int line, char const *expr, bool cond) +{ + if (!cond) { + FR_FAULT_LOG("SOFT ASSERT FAILED %s[%u]: %s", file, line, expr); +#if !defined(NDEBUG) + fr_fault(SIGABRT); +#endif + return false; + } + + return cond; +} + +/** Exit possibly printing a message about why we're exiting. + * + * @note Use the fr_exit(status) macro instead of calling this function directly. + * + * @param file where fr_exit() was called. + * @param line where fr_exit() was called. + * @param status we're exiting with. + */ +void NEVER_RETURNS _fr_exit(char const *file, int line, int status) +{ +#ifndef NDEBUG + char const *error = fr_strerror(); + + if (error && *error && (status != 0)) { + FR_FAULT_LOG("EXIT(%i) CALLED %s[%u]. Last error was: %s", status, file, line, error); + } else { + FR_FAULT_LOG("EXIT(%i) CALLED %s[%u]", status, file, line); + } +#endif + fr_debug_break(false); /* If running under GDB we'll break here */ + + exit(status); +} + +/** Exit possibly printing a message about why we're exiting. + * + * @note Use the fr_exit_now(status) macro instead of calling this function directly. + * + * @param file where fr_exit_now() was called. + * @param line where fr_exit_now() was called. + * @param status we're exiting with. + */ +void NEVER_RETURNS _fr_exit_now(char const *file, int line, int status) +{ +#ifndef NDEBUG + char const *error = fr_strerror(); + + if (error && (status != 0)) { + FR_FAULT_LOG("_EXIT(%i) CALLED %s[%u]. Last error was: %s", status, file, line, error); + } else { + FR_FAULT_LOG("_EXIT(%i) CALLED %s[%u]", status, file, line); + } +#endif + fr_debug_break(false); /* If running under GDB we'll break here */ + + _exit(status); +} |