X-Git-Url: http://git.efficios.com/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fcommon%2Frunas.c;h=84b3513ee52d0039d7b8a488838360ca499b81f5;hp=88ed773152cc7c959b81084fb58a93ee9c3409ae;hb=929f71ec24b58045319473f050a7f235f726ec78;hpb=edb025e87637ff74565647ad7756ecac46899d2a diff --git a/src/common/runas.c b/src/common/runas.c index 88ed77315..84b3513ee 100644 --- a/src/common/runas.c +++ b/src/common/runas.c @@ -2,21 +2,21 @@ * Copyright (C) 2011 - David Goulet * Mathieu Desnoyers * - * 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; only version 2 of the License. + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License, version 2 only, + * as published by the Free Software Foundation. * * 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 + * 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., 59 Temple - * Place - Suite 330, Boston, MA 02111-1307, USA. + * 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 Street, Fifth Floor, Boston, MA 02110-1301 USA. */ -#define _GNU_SOURCE +#define _LGPL_SOURCE #include #include #include @@ -28,305 +28,1257 @@ #include #include #include -#include +#include +#include +#include -#include -#include -#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include #include "runas.h" -#define RUNAS_CHILD_STACK_SIZE 10485760 +struct run_as_data; +struct run_as_ret; +typedef int (*run_as_fct)(struct run_as_data *data, struct run_as_ret *ret_value); -#ifndef __FreeBSD__ -# ifndef MAP_STACK -# define MAP_STACK 0 -# endif -#else /* FreeBSD MAP_STACK always return -ENOMEM */ -# define MAP_STACK 0 -#endif +struct run_as_mkdir_data { + char path[PATH_MAX]; + mode_t mode; +}; -#ifndef MAP_GROWSDOWN -#define MAP_GROWSDOWN 0 -#endif +struct run_as_open_data { + char path[PATH_MAX]; + int flags; + mode_t mode; +}; -#ifndef MAP_ANONYMOUS -#define MAP_ANONYMOUS MAP_ANON -#endif +struct run_as_unlink_data { + char path[PATH_MAX]; +}; + +struct run_as_rmdir_recursive_data { + char path[PATH_MAX]; +}; + +struct run_as_extract_elf_symbol_offset_data { + char function[LTTNG_SYMBOL_NAME_LEN]; +}; + +struct run_as_extract_sdt_probe_offsets_data { + char probe_name[LTTNG_SYMBOL_NAME_LEN]; + char provider_name[LTTNG_SYMBOL_NAME_LEN]; +}; + +struct run_as_mkdir_ret { + int ret; +}; + +struct run_as_open_ret { + int ret; +}; + +struct run_as_unlink_ret { + int ret; +}; + +struct run_as_rmdir_recursive_ret { + int ret; +}; + +struct run_as_extract_elf_symbol_offset_ret { + uint64_t offset; +}; + +struct run_as_extract_sdt_probe_offsets_ret { + uint32_t num_offset; + uint64_t offsets[LTTNG_KERNEL_MAX_UPROBE_NUM]; +}; + +enum run_as_cmd { + RUN_AS_MKDIR, + RUN_AS_OPEN, + RUN_AS_UNLINK, + RUN_AS_RMDIR_RECURSIVE, + RUN_AS_MKDIR_RECURSIVE, + RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET, + RUN_AS_EXTRACT_SDT_PROBE_OFFSETS, +}; struct run_as_data { - int (*cmd)(void *data); - void *data; + enum run_as_cmd cmd; + int fd; + union { + struct run_as_mkdir_data mkdir; + struct run_as_open_data open; + struct run_as_unlink_data unlink; + struct run_as_rmdir_recursive_data rmdir_recursive; + struct run_as_extract_elf_symbol_offset_data extract_elf_symbol_offset; + struct run_as_extract_sdt_probe_offsets_data extract_sdt_probe_offsets; + } u; uid_t uid; gid_t gid; - int retval_pipe; }; -struct run_as_mkdir_data { - const char *path; - mode_t mode; +/* + * The run_as_ret structure holds the returned value and status of the command. + * + * The `u` union field holds the return value of the command; in most cases it + * represents the success or the failure of the command. In more complex + * commands, it holds a computed value. + * + * The _errno field is the errno recorded after the execution of the command. + * + * The _error fields is used the signify that return status of the command. For + * simple commands returning `int` the _error field will be the same as the + * ret_int field. In complex commands, it signify the success or failure of the + * command. + * + */ +struct run_as_ret { + int fd; + union { + struct run_as_mkdir_ret mkdir; + struct run_as_open_ret open; + struct run_as_unlink_ret unlink; + struct run_as_rmdir_recursive_ret rmdir_recursive; + struct run_as_extract_elf_symbol_offset_ret extract_elf_symbol_offset; + struct run_as_extract_sdt_probe_offsets_ret extract_sdt_probe_offsets; + } u; + int _errno; + bool _error; }; -struct run_as_open_data { - const char *path; - int flags; - mode_t mode; +struct run_as_worker { + pid_t pid; /* Worker PID. */ + int sockpair[2]; + char *procname; }; +/* Single global worker per process (for now). */ +static struct run_as_worker *global_worker; +/* Lock protecting the worker. */ +static pthread_mutex_t worker_lock = PTHREAD_MUTEX_INITIALIZER; + +#ifdef VALGRIND +static +int use_clone(void) +{ + return 0; +} +#else +static +int use_clone(void) +{ + return !lttng_secure_getenv("LTTNG_DEBUG_NOCLONE"); +} +#endif + +LTTNG_HIDDEN +int _utils_mkdir_recursive_unsafe(const char *path, mode_t mode); + /* * Create recursively directory using the FULL path. */ static -int _mkdir_recursive(void *_data) +int _mkdir_recursive(struct run_as_data *data, struct run_as_ret *ret_value) { - struct run_as_mkdir_data *data = _data; const char *path; - char *p, tmp[PATH_MAX]; - struct stat statbuf; mode_t mode; - size_t len; - int ret; - path = data->path; - mode = data->mode; + path = data->u.mkdir.path; + mode = data->u.mkdir.mode; + + /* Safe to call as we have transitioned to the requested uid/gid. */ + ret_value->u.mkdir.ret = _utils_mkdir_recursive_unsafe(path, mode); + ret_value->_errno = errno; + ret_value->_error = (ret_value->u.mkdir.ret) ? true : false; + return ret_value->u.mkdir.ret; +} + +static +int _mkdir(struct run_as_data *data, struct run_as_ret *ret_value) +{ + ret_value->u.mkdir.ret = mkdir(data->u.mkdir.path, data->u.mkdir.mode); + ret_value->_errno = errno; + ret_value->_error = (ret_value->u.mkdir.ret) ? true : false; + return ret_value->u.mkdir.ret; +} + +static +int _open(struct run_as_data *data, struct run_as_ret *ret_value) +{ + ret_value->u.open.ret = open(data->u.open.path, data->u.open.flags, data->u.open.mode); + ret_value->fd = ret_value->u.open.ret; + ret_value->_errno = errno; + ret_value->_error = ret_value->u.open.ret < 0; + return ret_value->u.open.ret; +} + +static +int _unlink(struct run_as_data *data, struct run_as_ret *ret_value) +{ + ret_value->u.unlink.ret = unlink(data->u.unlink.path); + ret_value->_errno = errno; + ret_value->_error = (ret_value->u.unlink.ret) ? true : false; + return ret_value->u.unlink.ret; +} + +static +int _rmdir_recursive(struct run_as_data *data, struct run_as_ret *ret_value) +{ + ret_value->u.rmdir_recursive.ret = utils_recursive_rmdir(data->u.rmdir_recursive.path); + ret_value->_errno = errno; + ret_value->_error = (ret_value->u.rmdir_recursive.ret) ? true : false; + return ret_value->u.rmdir_recursive.ret; +} + +#ifdef HAVE_ELF_H +static +int _extract_elf_symbol_offset(struct run_as_data *data, + struct run_as_ret *ret_value) +{ + int ret = 0; + ret_value->_error = false; + + ret = lttng_elf_get_symbol_offset(data->fd, + data->u.extract_elf_symbol_offset.function, + &ret_value->u.extract_elf_symbol_offset.offset); + if (ret) { + DBG("Failed to extract ELF function offset"); + ret_value->_error = true; + } + + return ret; +} + +static +int _extract_sdt_probe_offsets(struct run_as_data *data, + struct run_as_ret *ret_value) +{ + int ret = 0; + uint64_t *offsets = NULL; + uint32_t num_offset; + + ret_value->_error = false; + + /* On success, this call allocates the offsets paramater. */ + ret = lttng_elf_get_sdt_probe_offsets(data->fd, + data->u.extract_sdt_probe_offsets.provider_name, + data->u.extract_sdt_probe_offsets.probe_name, + &offsets, &num_offset); + + if (ret) { + DBG("Failed to extract SDT probe offsets"); + ret_value->_error = true; + goto end; + } + + if (num_offset <= 0 || num_offset > LTTNG_KERNEL_MAX_UPROBE_NUM) { + DBG("Wrong number of probes."); + ret = -1; + ret_value->_error = true; + goto free_offset; + } + + /* Copy the content of the offsets array to the ret struct. */ + memcpy(ret_value->u.extract_sdt_probe_offsets.offsets, + offsets, num_offset * sizeof(uint64_t)); + + ret_value->u.extract_sdt_probe_offsets.num_offset = num_offset; + +free_offset: + free(offsets); +end: + return ret; +} +#else +static +int _extract_elf_symbol_offset(struct run_as_data *data, + struct run_as_ret *ret_value) +{ + ERR("Unimplemented runas command RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET"); + return -1; +} + +static +int _extract_sdt_probe_offsets(struct run_as_data *data, + struct run_as_ret *ret_value) +{ + ERR("Unimplemented runas command RUN_AS_EXTRACT_SDT_PROBE_OFFSETS"); + return -1; +} +#endif - ret = snprintf(tmp, sizeof(tmp), "%s", path); +static +run_as_fct run_as_enum_to_fct(enum run_as_cmd cmd) +{ + switch (cmd) { + case RUN_AS_MKDIR: + return _mkdir; + case RUN_AS_OPEN: + return _open; + case RUN_AS_UNLINK: + return _unlink; + case RUN_AS_RMDIR_RECURSIVE: + return _rmdir_recursive; + case RUN_AS_MKDIR_RECURSIVE: + return _mkdir_recursive; + case RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET: + return _extract_elf_symbol_offset; + case RUN_AS_EXTRACT_SDT_PROBE_OFFSETS: + return _extract_sdt_probe_offsets; + default: + ERR("Unknown command %d", (int) cmd); + return NULL; + } +} + +static +int do_send_fd(int sock, int fd) +{ + ssize_t len; + + if (fd < 0) { + ERR("Attempt to send invalid file descriptor to master (fd = %i)", fd); + /* Return 0 as this is not a fatal error. */ + return 0; + } + + len = lttcomm_send_fds_unix_sock(sock, &fd, 1); + if (len < 0) { + PERROR("lttcomm_send_fds_unix_sock"); + return -1; + } + return 0; +} + +static +int do_recv_fd(int sock, int *fd) +{ + ssize_t len; + + len = lttcomm_recv_fds_unix_sock(sock, fd, 1); + + if (!len) { + return -1; + } else if (len < 0) { + PERROR("lttcomm_recv_fds_unix_sock"); + return -1; + } + if (*fd < 0) { + ERR("Invalid file descriptor received from worker (fd = %i)", *fd); + /* Return 0 as this is not a fatal error. */ + return 0; + } + + return 0; +} + +static +int send_fd_to_worker(struct run_as_worker *worker, enum run_as_cmd cmd, int fd) +{ + int ret = 0; + + switch (cmd) { + case RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET: + case RUN_AS_EXTRACT_SDT_PROBE_OFFSETS: + break; + default: + return 0; + } + + if (fd < 0) { + ERR("Refusing to send invalid fd to worker (fd = %i)", fd); + return -1; + } + + ret = do_send_fd(worker->sockpair[0], fd); if (ret < 0) { - PERROR("snprintf mkdir"); - goto error; - } - - len = ret; - if (tmp[len - 1] == '/') { - tmp[len - 1] = 0; - } - - for (p = tmp + 1; *p; p++) { - if (*p == '/') { - *p = 0; - ret = stat(tmp, &statbuf); - if (ret < 0) { - ret = mkdir(tmp, mode); - if (ret < 0) { - if (!(errno == EEXIST)) { - PERROR("mkdir recursive"); - ret = -errno; - goto error; - } - } - } - *p = '/'; - } + PERROR("do_send_fd"); + ret = -1; + } + + return ret; +} + +static +int send_fd_to_master(struct run_as_worker *worker, enum run_as_cmd cmd, int fd) +{ + int ret = 0, ret_close = 0; + + switch (cmd) { + case RUN_AS_OPEN: + break; + default: + return 0; } - ret = mkdir(tmp, mode); + if (fd < 0) { + DBG("Not sending file descriptor to master as it is invalid (fd = %i)", fd); + return 0; + } + ret = do_send_fd(worker->sockpair[1], fd); if (ret < 0) { - if (!(errno == EEXIST)) { - PERROR("mkdir recursive last piece"); - ret = -errno; - } else { - ret = 0; - } + PERROR("do_send_fd error"); + ret = -1; + } + + ret_close = close(fd); + if (ret_close < 0) { + PERROR("close"); } -error: return ret; } static -int _mkdir(void *_data) +int recv_fd_from_worker(struct run_as_worker *worker, enum run_as_cmd cmd, int *fd) { - struct run_as_mkdir_data *data = _data; - return mkdir(data->path, data->mode); + int ret = 0; + + switch (cmd) { + case RUN_AS_OPEN: + break; + default: + return 0; + } + + ret = do_recv_fd(worker->sockpair[0], fd); + if (ret < 0) { + PERROR("do_recv_fd error"); + ret = -1; + } + + return ret; } static -int _open(void *_data) +int recv_fd_from_master(struct run_as_worker *worker, enum run_as_cmd cmd, int *fd) { - struct run_as_open_data *data = _data; - return open(data->path, data->flags, data->mode); + int ret = 0; + + switch (cmd) { + case RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET: + case RUN_AS_EXTRACT_SDT_PROBE_OFFSETS: + break; + default: + return 0; + } + + ret = do_recv_fd(worker->sockpair[1], fd); + if (ret < 0) { + PERROR("do_recv_fd error"); + ret = -1; + } + + return ret; } static -int child_run_as(void *_data) +int cleanup_received_fd(enum run_as_cmd cmd, int fd) { - struct run_as_data *data = _data; - size_t writelen, writeleft, index; - union { - int i; - char c[sizeof(int)]; - } sendret; - int ret; + int ret = 0; + + switch (cmd) { + case RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET: + case RUN_AS_EXTRACT_SDT_PROBE_OFFSETS: + break; + default: + return 0; + } + + if (fd < 0) { + return 0; + } + ret = close(fd); + if (ret < 0) { + PERROR("close error"); + ret = -1; + } + + return ret; +} + +/* + * Return < 0 on error, 0 if OK, 1 on hangup. + */ +static +int handle_one_cmd(struct run_as_worker *worker) +{ + int ret = 0; + struct run_as_data data; + ssize_t readlen, writelen; + struct run_as_ret sendret; + run_as_fct cmd; + uid_t prev_euid; + + memset(&sendret, 0, sizeof(sendret)); + sendret.fd = -1; + + /* + * Stage 1: Receive run_as_data struct from the master. + * The structure contains the command type and all the parameters needed for + * its execution + */ + readlen = lttcomm_recv_unix_sock(worker->sockpair[1], &data, + sizeof(data)); + if (readlen == 0) { + /* hang up */ + ret = 1; + goto end; + } + if (readlen < sizeof(data)) { + PERROR("lttcomm_recv_unix_sock error"); + ret = -1; + goto end; + } + + cmd = run_as_enum_to_fct(data.cmd); + if (!cmd) { + ret = -1; + goto end; + } /* - * Child: it is safe to drop egid and euid while sharing the - * file descriptors with the parent process, since we do not - * drop "uid": therefore, the user we are dropping egid/euid to - * cannot attach to this process with, e.g. ptrace, nor map this - * process memory. + * Stage 2: Receive file descriptor from master. + * Some commands need a file descriptor as input so if it's needed we + * receive the fd using the Unix socket. */ - if (data->gid != getegid()) { - ret = setegid(data->gid); + ret = recv_fd_from_master(worker, data.cmd, &data.fd); + if (ret < 0) { + PERROR("recv_fd_from_master error"); + ret = -1; + goto end; + } + + prev_euid = getuid(); + if (data.gid != getegid()) { + ret = setegid(data.gid); if (ret < 0) { - perror("setegid"); - return EXIT_FAILURE; + sendret._error = true; + sendret._errno = errno; + PERROR("setegid"); + goto write_return; } } - if (data->uid != geteuid()) { - ret = seteuid(data->uid); + if (data.uid != prev_euid) { + ret = seteuid(data.uid); if (ret < 0) { - perror("seteuid"); - return EXIT_FAILURE; + sendret._error = true; + sendret._errno = errno; + PERROR("seteuid"); + goto write_return; } } + /* * Also set umask to 0 for mkdir executable bit. */ umask(0); - sendret.i = (*data->cmd)(data->data); - /* send back return value */ - writeleft = sizeof(sendret); - index = 0; - do { - writelen = write(data->retval_pipe, &sendret.c[index], - writeleft); - if (writelen < 0) { - perror("write"); - return EXIT_FAILURE; + + /* + * Stage 3: Execute the command + */ + ret = (*cmd)(&data, &sendret); + if (ret < 0) { + DBG("Execution of command returned an error"); + } + +write_return: + ret = cleanup_received_fd(data.cmd, data.fd); + if (ret < 0) { + ERR("Error cleaning up FD"); + goto end; + } + + /* + * Stage 4: Send run_as_ret structure to the master. + * This structure contain the return value of the command and the errno. + */ + writelen = lttcomm_send_unix_sock(worker->sockpair[1], &sendret, + sizeof(sendret)); + if (writelen < sizeof(sendret)) { + PERROR("lttcomm_send_unix_sock error"); + ret = -1; + goto end; + } + + /* + * Stage 5: Send file descriptor to the master + * Some commands return a file descriptor so if it's needed we pass it back + * to the master using the Unix socket. + */ + ret = send_fd_to_master(worker, data.cmd, sendret.fd); + if (ret < 0) { + DBG("Sending FD to master returned an error"); + goto end; + } + + if (seteuid(prev_euid) < 0) { + PERROR("seteuid"); + ret = -1; + goto end; + } + ret = 0; +end: + return ret; +} + +static +int run_as_worker(struct run_as_worker *worker) +{ + int ret; + ssize_t writelen; + struct run_as_ret sendret; + size_t proc_orig_len; + + /* + * Initialize worker. Set a different process cmdline. + */ + proc_orig_len = strlen(worker->procname); + memset(worker->procname, 0, proc_orig_len); + strncpy(worker->procname, DEFAULT_RUN_AS_WORKER_NAME, proc_orig_len); + + ret = lttng_prctl(PR_SET_NAME, + (unsigned long) DEFAULT_RUN_AS_WORKER_NAME, 0, 0, 0); + if (ret && ret != -ENOSYS) { + /* Don't fail as this is not essential. */ + PERROR("prctl PR_SET_NAME"); + } + + memset(&sendret, 0, sizeof(sendret)); + + writelen = lttcomm_send_unix_sock(worker->sockpair[1], &sendret, + sizeof(sendret)); + if (writelen < sizeof(sendret)) { + PERROR("lttcomm_send_unix_sock error"); + ret = EXIT_FAILURE; + goto end; + } + + for (;;) { + ret = handle_one_cmd(worker); + if (ret < 0) { + ret = EXIT_FAILURE; + goto end; + } else if (ret > 0) { + break; + } else { + continue; /* Next command. */ } - writeleft -= writelen; - index += writelen; - } while (writeleft > 0); - return EXIT_SUCCESS; + } + ret = EXIT_SUCCESS; +end: + return ret; } static -int run_as(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid) +int run_as_cmd(struct run_as_worker *worker, + enum run_as_cmd cmd, + struct run_as_data *data, + struct run_as_ret *ret_value, + uid_t uid, gid_t gid) { - struct run_as_data run_as_data; int ret = 0; - int status; - pid_t pid; - int retval_pipe[2]; - ssize_t readlen, readleft, index; - void *child_stack; - union { - int i; - char c[sizeof(int)]; - } retval; + ssize_t readlen, writelen; /* * If we are non-root, we can only deal with our own uid. */ if (geteuid() != 0) { if (uid != geteuid()) { + ret = -1; + ret_value->_errno = EPERM; ERR("Client (%d)/Server (%d) UID mismatch (and sessiond is not root)", - uid, geteuid()); - return -EPERM; + (int) uid, (int) geteuid()); + goto end; } } - ret = pipe(retval_pipe); - if (ret < 0) { - perror("pipe"); - retval.i = ret; + data->cmd = cmd; + data->uid = uid; + data->gid = gid; + + /* + * Stage 1: Send the run_as_data struct to the worker process + */ + writelen = lttcomm_send_unix_sock(worker->sockpair[0], data, + sizeof(*data)); + if (writelen < sizeof(*data)) { + PERROR("Error writing message to run_as"); + ret = -1; + ret_value->_errno = EIO; goto end; } - run_as_data.data = data; - run_as_data.cmd = cmd; - run_as_data.uid = uid; - run_as_data.gid = gid; - run_as_data.retval_pipe = retval_pipe[1]; /* write end */ - child_stack = mmap(NULL, RUNAS_CHILD_STACK_SIZE, - PROT_WRITE | PROT_READ, - MAP_PRIVATE | MAP_GROWSDOWN | MAP_ANONYMOUS | MAP_STACK, - -1, 0); - if (child_stack == MAP_FAILED) { - perror("mmap"); - retval.i = -ENOMEM; - goto close_pipe; + + /* + * Stage 2: Send file descriptor to the worker process if needed + */ + ret = send_fd_to_worker(worker, data->cmd, data->fd); + if (ret) { + PERROR("do_send_fd error"); + ret = -1; + ret_value->_errno = EIO; + goto end; } + /* - * Pointing to the middle of the stack to support architectures - * where the stack grows up (HPPA). + * Stage 3: Wait for the execution of the command */ - pid = lttng_clone_files(child_run_as, child_stack + (RUNAS_CHILD_STACK_SIZE / 2), - &run_as_data); - if (pid < 0) { - perror("clone"); - retval.i = pid; - goto unmap_stack; - } - /* receive return value */ - readleft = sizeof(retval); - index = 0; - do { - readlen = read(retval_pipe[0], &retval.c[index], readleft); - if (readlen < 0) { - perror("read"); - ret = -1; - break; - } - readleft -= readlen; - index += readlen; - } while (readleft > 0); /* - * Parent: wait for child to return, in which case the - * shared memory map will have been created. + * Stage 4: Receive the run_as_ret struct containing the return value and + * errno */ - pid = waitpid(pid, &status, 0); - if (pid < 0 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) { - perror("wait"); - retval.i = -1; + readlen = lttcomm_recv_unix_sock(worker->sockpair[0], ret_value, + sizeof(*ret_value)); + if (!readlen) { + ERR("Run-as worker has hung-up during run_as_cmd"); + ret = -1; + ret_value->_errno = EIO; + goto end; + } else if (readlen < sizeof(*ret_value)) { + PERROR("Error reading response from run_as"); + ret = -1; + ret_value->_errno = errno; + goto end; } -unmap_stack: - ret = munmap(child_stack, RUNAS_CHILD_STACK_SIZE); + + if (ret_value->_error) { + /* Skip stage 5 on error as there will be no fd to receive. */ + goto end; + } + + /* + * Stage 5: Receive file descriptor if needed + */ + ret = recv_fd_from_worker(worker, data->cmd, &ret_value->fd); if (ret < 0) { - perror("munmap"); - retval.i = ret; + ERR("Error receiving fd"); + ret = -1; + ret_value->_errno = EIO; + } + +end: + return ret; +} + +/* + * This is for debugging ONLY and should not be considered secure. + */ +static +int run_as_noworker(enum run_as_cmd cmd, + struct run_as_data *data, struct run_as_ret *ret_value, + uid_t uid, gid_t gid) +{ + int ret, saved_errno; + mode_t old_mask; + run_as_fct fct; + + fct = run_as_enum_to_fct(cmd); + if (!fct) { + errno = -ENOSYS; + ret = -1; + goto end; + } + old_mask = umask(0); + ret = fct(data, ret_value); + saved_errno = ret_value->_errno; + umask(old_mask); + errno = saved_errno; +end: + return ret; +} + +static +int reset_sighandler(void) +{ + int sig; + + DBG("Resetting run_as worker signal handlers to default"); + for (sig = 1; sig <= 31; sig++) { + (void) signal(sig, SIG_DFL); + } + return 0; +} + +static +void worker_sighandler(int sig) +{ + const char *signame; + + /* + * The worker will inherit its parent's signals since they are part of + * the same process group. However, in the case of SIGINT and SIGTERM, + * we want to give the worker a chance to teardown gracefully when its + * parent closes the command socket. + */ + switch (sig) { + case SIGINT: + signame = "SIGINT"; + break; + case SIGTERM: + signame = "SIGTERM"; + break; + default: + signame = NULL; + } + + if (signame) { + DBG("run_as worker received signal %s", signame); + } else { + DBG("run_as_worker received signal %d", sig); + } +} + +static +int set_worker_sighandlers(void) +{ + int ret = 0; + sigset_t sigset; + struct sigaction sa; + + if ((ret = sigemptyset(&sigset)) < 0) { + PERROR("sigemptyset"); + goto end; + } + + sa.sa_handler = worker_sighandler; + sa.sa_mask = sigset; + sa.sa_flags = 0; + if ((ret = sigaction(SIGINT, &sa, NULL)) < 0) { + PERROR("sigaction SIGINT"); + goto end; + } + + if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) { + PERROR("sigaction SIGTERM"); + goto end; + } + + DBG("run_as signal handler set for SIGTERM and SIGINT"); +end: + return ret; +} + +static +int run_as_create_worker_no_lock(const char *procname, + post_fork_cleanup_cb clean_up_func, + void *clean_up_user_data) +{ + pid_t pid; + int i, ret = 0; + ssize_t readlen; + struct run_as_ret recvret; + struct run_as_worker *worker; + + assert(!global_worker); + if (!use_clone()) { + /* + * Don't initialize a worker, all run_as tasks will be performed + * in the current process. + */ + ret = 0; + goto end; + } + worker = zmalloc(sizeof(*worker)); + if (!worker) { + ret = -ENOMEM; + goto end; + } + worker->procname = strdup(procname); + if (!worker->procname) { + ret = -ENOMEM; + goto error_procname_alloc; + } + /* Create unix socket. */ + if (lttcomm_create_anon_unix_socketpair(worker->sockpair) < 0) { + ret = -1; + goto error_sock; + } + + /* Fork worker. */ + pid = fork(); + if (pid < 0) { + PERROR("fork"); + ret = -1; + goto error_fork; + } else if (pid == 0) { + /* Child */ + + reset_sighandler(); + + set_worker_sighandlers(); + if (clean_up_func) { + if (clean_up_func(clean_up_user_data) < 0) { + ERR("Run-as post-fork clean-up failed, exiting."); + exit(EXIT_FAILURE); + } + } + + /* Just close, no shutdown. */ + if (close(worker->sockpair[0])) { + PERROR("close"); + exit(EXIT_FAILURE); + } + + /* + * Close all FDs aside from STDIN, STDOUT, STDERR and sockpair[1] + * Sockpair[1] is used as a control channel with the master + */ + for (i = 3; i < sysconf(_SC_OPEN_MAX); i++) { + if (i != worker->sockpair[1]) { + (void) close(i); + } + } + + worker->sockpair[0] = -1; + ret = run_as_worker(worker); + if (lttcomm_close_unix_sock(worker->sockpair[1])) { + PERROR("close"); + ret = -1; + } + worker->sockpair[1] = -1; + free(worker->procname); + free(worker); + LOG(ret ? PRINT_ERR : PRINT_DBG, "run_as worker exiting (ret = %d)", ret); + exit(ret ? EXIT_FAILURE : EXIT_SUCCESS); + } else { + /* Parent */ + + /* Just close, no shutdown. */ + if (close(worker->sockpair[1])) { + PERROR("close"); + ret = -1; + goto error_fork; + } + worker->sockpair[1] = -1; + worker->pid = pid; + /* Wait for worker to become ready. */ + readlen = lttcomm_recv_unix_sock(worker->sockpair[0], + &recvret, sizeof(recvret)); + if (readlen < sizeof(recvret)) { + ERR("readlen: %zd", readlen); + PERROR("Error reading response from run_as at creation"); + ret = -1; + goto error_fork; + } + global_worker = worker; } -close_pipe: - close(retval_pipe[0]); - close(retval_pipe[1]); end: - return retval.i; + return ret; + + /* Error handling. */ +error_fork: + for (i = 0; i < 2; i++) { + if (worker->sockpair[i] < 0) { + continue; + } + if (lttcomm_close_unix_sock(worker->sockpair[i])) { + PERROR("close"); + } + worker->sockpair[i] = -1; + } +error_sock: + free(worker->procname); +error_procname_alloc: + free(worker); + return ret; } +static +int run_as_restart_worker(struct run_as_worker *worker) +{ + int ret = 0; + char *procname = NULL; + + procname = worker->procname; + + /* Close socket to run_as worker process and clean up the zombie process */ + run_as_destroy_worker(); + + /* Create a new run_as worker process*/ + ret = run_as_create_worker_no_lock(procname, NULL, NULL); + if (ret < 0 ) { + ERR("Restarting the worker process failed"); + ret = -1; + goto err; + } +err: + return ret; +} + +static +int run_as(enum run_as_cmd cmd, struct run_as_data *data, + struct run_as_ret *ret_value, uid_t uid, gid_t gid) +{ + int ret, saved_errno; + + pthread_mutex_lock(&worker_lock); + if (use_clone()) { + DBG("Using run_as worker"); + + assert(global_worker); + + ret = run_as_cmd(global_worker, cmd, data, ret_value, uid, gid); + saved_errno = ret_value->_errno; + + /* + * If the worker thread crashed the errno is set to EIO. we log + * the error and start a new worker process. + */ + if (ret == -1 && saved_errno == EIO) { + DBG("Socket closed unexpectedly... " + "Restarting the worker process"); + ret = run_as_restart_worker(global_worker); + if (ret == -1) { + ERR("Failed to restart worker process."); + goto err; + } + } + } else { + DBG("Using run_as without worker"); + ret = run_as_noworker(cmd, data, ret_value, uid, gid); + } +err: + pthread_mutex_unlock(&worker_lock); + return ret; +} + +LTTNG_HIDDEN int run_as_mkdir_recursive(const char *path, mode_t mode, uid_t uid, gid_t gid) { - struct run_as_mkdir_data data; + struct run_as_data data; + struct run_as_ret ret; + memset(&data, 0, sizeof(data)); + memset(&ret, 0, sizeof(ret)); DBG3("mkdir() recursive %s with mode %d for uid %d and gid %d", - path, mode, uid, gid); - data.path = path; - data.mode = mode; - return run_as(_mkdir_recursive, &data, uid, gid); + path, (int) mode, (int) uid, (int) gid); + strncpy(data.u.mkdir.path, path, PATH_MAX - 1); + data.u.mkdir.path[PATH_MAX - 1] = '\0'; + data.u.mkdir.mode = mode; + + run_as(RUN_AS_MKDIR_RECURSIVE, &data, &ret, uid, gid); + errno = ret._errno; + return ret.u.mkdir.ret; } +LTTNG_HIDDEN int run_as_mkdir(const char *path, mode_t mode, uid_t uid, gid_t gid) { - struct run_as_mkdir_data data; + struct run_as_data data; + struct run_as_ret ret; + + memset(&data, 0, sizeof(data)); + memset(&ret, 0, sizeof(ret)); DBG3("mkdir() %s with mode %d for uid %d and gid %d", - path, mode, uid, gid); - data.path = path; - data.mode = mode; - return run_as(_mkdir, &data, uid, gid); + path, (int) mode, (int) uid, (int) gid); + strncpy(data.u.mkdir.path, path, PATH_MAX - 1); + data.u.mkdir.path[PATH_MAX - 1] = '\0'; + data.u.mkdir.mode = mode; + run_as(RUN_AS_MKDIR, &data, &ret, uid, gid); + errno = ret._errno; + return ret.u.mkdir.ret; } -/* - * Note: open_run_as is currently not working. We'd need to pass the fd - * opened in the child to the parent. - */ +LTTNG_HIDDEN int run_as_open(const char *path, int flags, mode_t mode, uid_t uid, gid_t gid) { - struct run_as_open_data data; + struct run_as_data data; + struct run_as_ret ret; + + memset(&data, 0, sizeof(data)); + memset(&ret, 0, sizeof(ret)); DBG3("open() %s with flags %X mode %d for uid %d and gid %d", - path, flags, mode, uid, gid); - data.path = path; - data.flags = flags; - data.mode = mode; - return run_as(_open, &data, uid, gid); + path, flags, (int) mode, (int) uid, (int) gid); + strncpy(data.u.open.path, path, PATH_MAX - 1); + data.u.open.path[PATH_MAX - 1] = '\0'; + data.u.open.flags = flags; + data.u.open.mode = mode; + run_as(RUN_AS_OPEN, &data, &ret, uid, gid); + errno = ret._errno; + ret.u.open.ret = ret.fd; + return ret.u.open.ret; +} + +LTTNG_HIDDEN +int run_as_unlink(const char *path, uid_t uid, gid_t gid) +{ + struct run_as_data data; + struct run_as_ret ret; + + memset(&data, 0, sizeof(data)); + memset(&ret, 0, sizeof(ret)); + + DBG3("unlink() %s with for uid %d and gid %d", + path, (int) uid, (int) gid); + strncpy(data.u.unlink.path, path, PATH_MAX - 1); + data.u.unlink.path[PATH_MAX - 1] = '\0'; + run_as(RUN_AS_UNLINK, &data, &ret, uid, gid); + errno = ret._errno; + return ret.u.unlink.ret; +} + +LTTNG_HIDDEN +int run_as_rmdir_recursive(const char *path, uid_t uid, gid_t gid) +{ + struct run_as_data data; + struct run_as_ret ret; + + memset(&data, 0, sizeof(data)); + memset(&ret, 0, sizeof(ret)); + + DBG3("rmdir_recursive() %s with for uid %d and gid %d", + path, (int) uid, (int) gid); + strncpy(data.u.rmdir_recursive.path, path, PATH_MAX - 1); + data.u.rmdir_recursive.path[PATH_MAX - 1] = '\0'; + run_as(RUN_AS_RMDIR_RECURSIVE, &data, &ret, uid, gid); + errno = ret._errno; + return ret.u.rmdir_recursive.ret; +} + +LTTNG_HIDDEN +int run_as_extract_elf_symbol_offset(int fd, const char* function, + uid_t uid, gid_t gid, uint64_t *offset) +{ + struct run_as_data data; + struct run_as_ret ret; + + memset(&data, 0, sizeof(data)); + memset(&ret, 0, sizeof(ret)); + + DBG3("extract_elf_symbol_offset() on fd=%d and function=%s " + "with for uid %d and gid %d", fd, function, (int) uid, (int) gid); + + data.fd = fd; + + strncpy(data.u.extract_elf_symbol_offset.function, function, LTTNG_SYMBOL_NAME_LEN - 1); + + data.u.extract_elf_symbol_offset.function[LTTNG_SYMBOL_NAME_LEN - 1] = '\0'; + + run_as(RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET, &data, &ret, uid, gid); + + errno = ret._errno; + + if (ret._error) { + return -1; + } + + *offset = ret.u.extract_elf_symbol_offset.offset; + return 0; +} + +LTTNG_HIDDEN +int run_as_extract_sdt_probe_offsets(int fd, const char* provider_name, + const char* probe_name, uid_t uid, gid_t gid, + uint64_t **offsets, uint32_t *num_offset) +{ + struct run_as_data data; + struct run_as_ret ret; + + memset(&data, 0, sizeof(data)); + memset(&ret, 0, sizeof(ret)); + + DBG3("extract_sdt_probe_offsets() on fd=%d, probe_name=%s and " + "provider_name=%s with for uid %d and gid %d", fd, probe_name, + provider_name, (int) uid, (int) gid); + + data.fd = fd; + + strncpy(data.u.extract_sdt_probe_offsets.probe_name, probe_name, LTTNG_SYMBOL_NAME_LEN - 1); + strncpy(data.u.extract_sdt_probe_offsets.provider_name, provider_name, LTTNG_SYMBOL_NAME_LEN - 1); + + data.u.extract_sdt_probe_offsets.probe_name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0'; + data.u.extract_sdt_probe_offsets.provider_name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0'; + + run_as(RUN_AS_EXTRACT_SDT_PROBE_OFFSETS, &data, &ret, uid, gid); + + errno = ret._errno; + + if (ret._error) { + return -1; + } + + *num_offset = ret.u.extract_sdt_probe_offsets.num_offset; + + *offsets = zmalloc(*num_offset * sizeof(uint64_t)); + if (!*offsets) { + return -ENOMEM; + } + + memcpy(*offsets, ret.u.extract_sdt_probe_offsets.offsets, *num_offset * sizeof(uint64_t)); + return 0; +} + +LTTNG_HIDDEN +int run_as_create_worker(const char *procname, + post_fork_cleanup_cb clean_up_func, + void *clean_up_user_data) +{ + int ret; + + pthread_mutex_lock(&worker_lock); + ret = run_as_create_worker_no_lock(procname, clean_up_func, + clean_up_user_data); + pthread_mutex_unlock(&worker_lock); + return ret; +} + +LTTNG_HIDDEN +void run_as_destroy_worker(void) +{ + struct run_as_worker *worker = global_worker; + + DBG("Destroying run_as worker"); + pthread_mutex_lock(&worker_lock); + if (!worker) { + goto end; + } + /* Close unix socket */ + DBG("Closing run_as worker socket"); + if (lttcomm_close_unix_sock(worker->sockpair[0])) { + PERROR("close"); + } + worker->sockpair[0] = -1; + /* Wait for worker. */ + for (;;) { + int status; + pid_t wait_ret; + + wait_ret = waitpid(worker->pid, &status, 0); + if (wait_ret < 0) { + if (errno == EINTR) { + continue; + } + PERROR("waitpid"); + break; + } + + if (WIFEXITED(status)) { + LOG(WEXITSTATUS(status) == 0 ? PRINT_DBG : PRINT_ERR, + DEFAULT_RUN_AS_WORKER_NAME " terminated with status code %d", + WEXITSTATUS(status)); + break; + } else if (WIFSIGNALED(status)) { + ERR(DEFAULT_RUN_AS_WORKER_NAME " was killed by signal %d", + WTERMSIG(status)); + break; + } + } + free(worker->procname); + free(worker); + global_worker = NULL; +end: + pthread_mutex_unlock(&worker_lock); }