/* * Copyright (C) 2011 - David Goulet * Mathieu Desnoyers * 2019 - Jérémie Galarneau * * 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 * 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 Street, Fifth Floor, Boston, MA 02110-1301 USA. */ #define _LGPL_SOURCE #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "runas.h" struct run_as_data; struct run_as_ret; typedef int (*run_as_fct)(struct run_as_data *data, struct run_as_ret *ret_value); enum run_as_cmd { RUN_AS_MKDIR, RUN_AS_MKDIRAT, RUN_AS_MKDIR_RECURSIVE, RUN_AS_MKDIRAT_RECURSIVE, RUN_AS_OPEN, RUN_AS_OPENAT, RUN_AS_UNLINK, RUN_AS_UNLINKAT, RUN_AS_RMDIR, RUN_AS_RMDIRAT, RUN_AS_RMDIR_RECURSIVE, RUN_AS_RMDIRAT_RECURSIVE, RUN_AS_RENAME, RUN_AS_RENAMEAT, RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET, RUN_AS_EXTRACT_SDT_PROBE_OFFSETS, }; struct run_as_mkdir_data { int dirfd; char path[LTTNG_PATH_MAX]; mode_t mode; } LTTNG_PACKED; struct run_as_open_data { int dirfd; char path[LTTNG_PATH_MAX]; int flags; mode_t mode; } LTTNG_PACKED; struct run_as_unlink_data { int dirfd; char path[LTTNG_PATH_MAX]; } LTTNG_PACKED; struct run_as_rmdir_data { int dirfd; char path[LTTNG_PATH_MAX]; int flags; /* enum lttng_directory_handle_rmdir_recursive_flags */ } LTTNG_PACKED; struct run_as_extract_elf_symbol_offset_data { int fd; char function[LTTNG_SYMBOL_NAME_LEN]; } LTTNG_PACKED; struct run_as_extract_sdt_probe_offsets_data { int fd; char probe_name[LTTNG_SYMBOL_NAME_LEN]; char provider_name[LTTNG_SYMBOL_NAME_LEN]; } LTTNG_PACKED; struct run_as_rename_data { /* * [0] = old_dirfd * [1] = new_dirfd */ int dirfds[2]; char old_path[LTTNG_PATH_MAX]; char new_path[LTTNG_PATH_MAX]; } LTTNG_PACKED; struct run_as_open_ret { int fd; } LTTNG_PACKED; struct run_as_extract_elf_symbol_offset_ret { uint64_t offset; } LTTNG_PACKED; struct run_as_extract_sdt_probe_offsets_ret { uint32_t num_offset; uint64_t offsets[LTTNG_KERNEL_MAX_UPROBE_NUM]; } LTTNG_PACKED; struct run_as_data { enum run_as_cmd cmd; union { struct run_as_mkdir_data mkdir; struct run_as_open_data open; struct run_as_unlink_data unlink; struct run_as_rmdir_data rmdir; struct run_as_rename_data rename; 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; } LTTNG_PACKED; /* * 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 { union { int ret; struct run_as_open_ret open; 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; } LTTNG_PACKED; #define COMMAND_IN_FDS(data_ptr) ({ \ int *fds = NULL; \ if (command_properties[data_ptr->cmd].in_fds_offset != -1) { \ fds = (int *) ((char *) data_ptr + command_properties[data_ptr->cmd].in_fds_offset); \ } \ fds; \ }) #define COMMAND_OUT_FDS(cmd, ret_ptr) ({ \ int *fds = NULL; \ if (command_properties[cmd].out_fds_offset != -1) { \ fds = (int *) ((char *) ret_ptr + command_properties[cmd].out_fds_offset); \ } \ fds; \ }) #define COMMAND_IN_FD_COUNT(data_ptr) ({ \ command_properties[data_ptr->cmd].in_fd_count; \ }) #define COMMAND_OUT_FD_COUNT(cmd) ({ \ command_properties[cmd].out_fd_count; \ }) #define COMMAND_USE_CWD_FD(data_ptr) command_properties[data_ptr->cmd].use_cwd_fd struct run_as_command_properties { /* Set to -1 when not applicable. */ ptrdiff_t in_fds_offset, out_fds_offset; unsigned int in_fd_count, out_fd_count; bool use_cwd_fd; }; static const struct run_as_command_properties command_properties[] = { [RUN_AS_MKDIR] = { .in_fds_offset = offsetof(struct run_as_data, u.mkdir.dirfd), .in_fd_count = 1, .out_fds_offset = -1, .out_fd_count = 0, .use_cwd_fd = true, }, [RUN_AS_MKDIRAT] = { .in_fds_offset = offsetof(struct run_as_data, u.mkdir.dirfd), .in_fd_count = 1, .out_fds_offset = -1, .out_fd_count = 0, .use_cwd_fd = false, }, [RUN_AS_MKDIR_RECURSIVE] = { .in_fds_offset = offsetof(struct run_as_data, u.mkdir.dirfd), .in_fd_count = 1, .out_fds_offset = -1, .out_fd_count = 0, .use_cwd_fd = true, }, [RUN_AS_MKDIRAT_RECURSIVE] = { .in_fds_offset = offsetof(struct run_as_data, u.mkdir.dirfd), .in_fd_count = 1, .out_fds_offset = -1, .out_fd_count = 0, .use_cwd_fd = false, }, [RUN_AS_OPEN] = { .in_fds_offset = offsetof(struct run_as_data, u.open.dirfd), .in_fd_count = 1, .out_fds_offset = offsetof(struct run_as_ret, u.open.fd), .out_fd_count = 1, .use_cwd_fd = true, }, [RUN_AS_OPENAT] = { .in_fds_offset = offsetof(struct run_as_data, u.open.dirfd), .in_fd_count = 1, .out_fds_offset = offsetof(struct run_as_ret, u.open.fd), .out_fd_count = 1, .use_cwd_fd = false, }, [RUN_AS_UNLINK] = { .in_fds_offset = offsetof(struct run_as_data, u.unlink.dirfd), .in_fd_count = 1, .out_fds_offset = -1, .out_fd_count = 0, .use_cwd_fd = true, }, [RUN_AS_UNLINKAT] = { .in_fds_offset = offsetof(struct run_as_data, u.unlink.dirfd), .in_fd_count = 1, .out_fds_offset = -1, .out_fd_count = 0, .use_cwd_fd = false, }, [RUN_AS_RMDIR_RECURSIVE] = { .in_fds_offset = offsetof(struct run_as_data, u.rmdir.dirfd), .in_fd_count = 1, .out_fds_offset = -1, .out_fd_count = 0, .use_cwd_fd = true, }, [RUN_AS_RMDIRAT_RECURSIVE] = { .in_fds_offset = offsetof(struct run_as_data, u.rmdir.dirfd), .in_fd_count = 1, .out_fds_offset = -1, .out_fd_count = 0, .use_cwd_fd = false, }, [RUN_AS_RMDIR] = { .in_fds_offset = offsetof(struct run_as_data, u.rmdir.dirfd), .in_fd_count = 1, .out_fds_offset = -1, .out_fd_count = 0, .use_cwd_fd = true, }, [RUN_AS_RMDIRAT] = { .in_fds_offset = offsetof(struct run_as_data, u.rmdir.dirfd), .in_fd_count = 1, .out_fds_offset = -1, .out_fd_count = 0, .use_cwd_fd = false, }, [RUN_AS_RENAME] = { .in_fds_offset = offsetof(struct run_as_data, u.rename.dirfds), .in_fd_count = 2, .out_fds_offset = -1, .out_fd_count = 0, .use_cwd_fd = true, }, [RUN_AS_RENAMEAT] = { .in_fds_offset = offsetof(struct run_as_data, u.rename.dirfds), .in_fd_count = 2, .out_fds_offset = -1, .out_fd_count = 0, .use_cwd_fd = false, }, [RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET] = { .in_fds_offset = offsetof(struct run_as_data, u.extract_elf_symbol_offset.fd), .in_fd_count = 1, .out_fds_offset = -1, .out_fd_count = 0, .use_cwd_fd = false, }, [RUN_AS_EXTRACT_SDT_PROBE_OFFSETS] = { .in_fds_offset = offsetof(struct run_as_data, u.extract_sdt_probe_offsets.fd), .in_fd_count = 1, .out_fds_offset = -1, .out_fd_count = 0, .use_cwd_fd = false, }, }; 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 /* * Create recursively directory using the FULL path. */ static int _mkdirat_recursive(struct run_as_data *data, struct run_as_ret *ret_value) { const char *path; mode_t mode; struct lttng_directory_handle handle; path = data->u.mkdir.path; mode = data->u.mkdir.mode; (void) lttng_directory_handle_init_from_dirfd(&handle, data->u.mkdir.dirfd); /* Ownership of dirfd is transferred to the handle. */ data->u.mkdir.dirfd = -1; /* Safe to call as we have transitioned to the requested uid/gid. */ ret_value->u.ret = lttng_directory_handle_create_subdirectory_recursive( &handle, path, mode); ret_value->_errno = errno; ret_value->_error = (ret_value->u.ret) ? true : false; lttng_directory_handle_fini(&handle); return ret_value->u.ret; } static int _mkdirat(struct run_as_data *data, struct run_as_ret *ret_value) { const char *path; mode_t mode; struct lttng_directory_handle handle; path = data->u.mkdir.path; mode = data->u.mkdir.mode; (void) lttng_directory_handle_init_from_dirfd(&handle, data->u.mkdir.dirfd); /* Ownership of dirfd is transferred to the handle. */ data->u.mkdir.dirfd = -1; /* Safe to call as we have transitioned to the requested uid/gid. */ ret_value->u.ret = lttng_directory_handle_create_subdirectory( &handle, path, mode); ret_value->_errno = errno; ret_value->_error = (ret_value->u.ret) ? true : false; lttng_directory_handle_fini(&handle); return ret_value->u.ret; } static int _open(struct run_as_data *data, struct run_as_ret *ret_value) { int fd; struct lttng_directory_handle handle; (void) lttng_directory_handle_init_from_dirfd(&handle, data->u.open.dirfd); /* Ownership of dirfd is transferred to the handle. */ data->u.open.dirfd = -1; fd = lttng_directory_handle_open_file(&handle, data->u.open.path, data->u.open.flags, data->u.open.mode); if (fd < 0) { ret_value->u.ret = -1; ret_value->u.open.fd = -1; } else { ret_value->u.ret = 0; ret_value->u.open.fd = fd; } ret_value->_errno = errno; ret_value->_error = fd < 0; lttng_directory_handle_fini(&handle); return ret_value->u.ret; } static int _unlink(struct run_as_data *data, struct run_as_ret *ret_value) { struct lttng_directory_handle handle; (void) lttng_directory_handle_init_from_dirfd(&handle, data->u.unlink.dirfd); /* Ownership of dirfd is transferred to the handle. */ data->u.unlink.dirfd = -1; ret_value->u.ret = lttng_directory_handle_unlink_file(&handle, data->u.unlink.path); ret_value->_errno = errno; ret_value->_error = (ret_value->u.ret) ? true : false; lttng_directory_handle_fini(&handle); return ret_value->u.ret; } static int _rmdir(struct run_as_data *data, struct run_as_ret *ret_value) { struct lttng_directory_handle handle; (void) lttng_directory_handle_init_from_dirfd(&handle, data->u.rmdir.dirfd); /* Ownership of dirfd is transferred to the handle. */ data->u.rmdir.dirfd = -1; ret_value->u.ret = lttng_directory_handle_remove_subdirectory( &handle, data->u.rmdir.path); ret_value->_errno = errno; ret_value->_error = (ret_value->u.ret) ? true : false; lttng_directory_handle_fini(&handle); return ret_value->u.ret; } static int _rmdir_recursive(struct run_as_data *data, struct run_as_ret *ret_value) { struct lttng_directory_handle handle; (void) lttng_directory_handle_init_from_dirfd(&handle, data->u.rmdir.dirfd); /* Ownership of dirfd is transferred to the handle. */ data->u.rmdir.dirfd = -1; ret_value->u.ret = lttng_directory_handle_remove_subdirectory_recursive( &handle, data->u.rmdir.path, data->u.rmdir.flags); ret_value->_errno = errno; ret_value->_error = (ret_value->u.ret) ? true : false; lttng_directory_handle_fini(&handle); return ret_value->u.ret; } static int _rename(struct run_as_data *data, struct run_as_ret *ret_value) { const char *old_path, *new_path; struct lttng_directory_handle old_handle, new_handle; old_path = data->u.rename.old_path; new_path = data->u.rename.new_path; (void) lttng_directory_handle_init_from_dirfd(&old_handle, data->u.rename.dirfds[0]); (void) lttng_directory_handle_init_from_dirfd(&new_handle, data->u.rename.dirfds[1]); /* Ownership of dirfds are transferred to the handles. */ data->u.rename.dirfds[0] = data->u.rename.dirfds[1] = -1; /* Safe to call as we have transitioned to the requested uid/gid. */ ret_value->u.ret = lttng_directory_handle_rename( &old_handle, old_path, &new_handle, new_path); ret_value->_errno = errno; ret_value->_error = (ret_value->u.ret) ? true : false; lttng_directory_handle_fini(&old_handle); lttng_directory_handle_fini(&new_handle); return ret_value->u.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; uint64_t offset; ret_value->_error = false; ret = lttng_elf_get_symbol_offset(data->u.extract_elf_symbol_offset.fd, data->u.extract_elf_symbol_offset.function, &offset); if (ret) { DBG("Failed to extract ELF function offset"); ret_value->_error = true; } ret_value->u.extract_elf_symbol_offset.offset = offset; 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->u.extract_sdt_probe_offsets.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 static run_as_fct run_as_enum_to_fct(enum run_as_cmd cmd) { switch (cmd) { case RUN_AS_MKDIR: case RUN_AS_MKDIRAT: return _mkdirat; case RUN_AS_MKDIR_RECURSIVE: case RUN_AS_MKDIRAT_RECURSIVE: return _mkdirat_recursive; case RUN_AS_OPEN: case RUN_AS_OPENAT: return _open; case RUN_AS_UNLINK: case RUN_AS_UNLINKAT: return _unlink; case RUN_AS_RMDIR: case RUN_AS_RMDIRAT: return _rmdir; case RUN_AS_RMDIR_RECURSIVE: case RUN_AS_RMDIRAT_RECURSIVE: return _rmdir_recursive; case RUN_AS_RENAME: case RUN_AS_RENAMEAT: return _rename; 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_fds(int sock, const int *fds, unsigned int fd_count) { ssize_t len; unsigned int i; for (i = 0; i < fd_count; i++) { if (fds[i] < 0) { ERR("Attempt to send invalid file descriptor to master (fd = %i)", fds[i]); /* Return 0 as this is not a fatal error. */ return 0; } } len = lttcomm_send_fds_unix_sock(sock, fds, fd_count); return len < 0 ? -1 : 0; } static int do_recv_fds(int sock, int *fds, unsigned int fd_count) { int ret = 0; unsigned int i; ssize_t len; len = lttcomm_recv_fds_unix_sock(sock, fds, fd_count); if (len == 0) { ret = -1; goto end; } else if (len < 0) { PERROR("Failed to receive file descriptors from socket"); ret = -1; goto end; } for (i = 0; i < fd_count; i++) { if (fds[i] < 0) { ERR("Invalid file descriptor received from worker (fd = %i)", fds[i]); /* Return 0 as this is not a fatal error. */ } } end: return ret; } static int send_fds_to_worker(const struct run_as_worker *worker, const struct run_as_data *data) { int ret = 0; unsigned int i; if (COMMAND_USE_CWD_FD(data) || COMMAND_IN_FD_COUNT(data) == 0) { goto end; } for (i = 0; i < COMMAND_IN_FD_COUNT(data); i++) { if (COMMAND_IN_FDS(data)[i] < 0) { ERR("Refusing to send invalid fd to worker (fd = %i)", COMMAND_IN_FDS(data)[i]); ret = -1; goto end; } } ret = do_send_fds(worker->sockpair[0], COMMAND_IN_FDS(data), COMMAND_IN_FD_COUNT(data)); if (ret < 0) { PERROR("Failed to send file descriptor to run-as worker"); ret = -1; goto end; } end: return ret; } static int send_fds_to_master(struct run_as_worker *worker, enum run_as_cmd cmd, struct run_as_ret *run_as_ret) { int ret = 0; unsigned int i; if (COMMAND_OUT_FD_COUNT(cmd) == 0) { goto end; } ret = do_send_fds(worker->sockpair[1], COMMAND_OUT_FDS(cmd, run_as_ret), COMMAND_OUT_FD_COUNT(cmd)); if (ret < 0) { PERROR("Failed to send file descriptor to master process"); goto end; } for (i = 0; i < COMMAND_OUT_FD_COUNT(cmd); i++) { int ret_close = close(COMMAND_OUT_FDS(cmd, run_as_ret)[i]); if (ret_close < 0) { PERROR("Failed to close result file descriptor"); } } end: return ret; } static int recv_fds_from_worker(const struct run_as_worker *worker, enum run_as_cmd cmd, struct run_as_ret *run_as_ret) { int ret = 0; if (COMMAND_OUT_FD_COUNT(cmd) == 0) { goto end; } ret = do_recv_fds(worker->sockpair[0], COMMAND_OUT_FDS(cmd, run_as_ret), COMMAND_OUT_FD_COUNT(cmd)); if (ret < 0) { PERROR("Failed to receive file descriptor from run-as worker"); ret = -1; } end: return ret; } static int recv_fds_from_master(struct run_as_worker *worker, struct run_as_data *data) { int ret = 0; if (COMMAND_USE_CWD_FD(data)) { unsigned int i; for (i = 0; i < COMMAND_IN_FD_COUNT(data); i++) { COMMAND_IN_FDS(data)[i] = AT_FDCWD; } goto end; } ret = do_recv_fds(worker->sockpair[1], COMMAND_IN_FDS(data), COMMAND_IN_FD_COUNT(data)); if (ret < 0) { PERROR("Failed to receive file descriptors from master process"); ret = -1; } end: return ret; } static int cleanup_received_fds(struct run_as_data *data) { int ret = 0, i; for (i = 0; i < COMMAND_IN_FD_COUNT(data); i++) { if (COMMAND_IN_FDS(data)[i] == -1) { continue; } ret = close(COMMAND_IN_FDS(data)[i]); if (ret) { PERROR("Failed to close file descriptor received fd in run-as worker"); goto end; } } end: 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; /* * 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; } /* * 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. */ ret = recv_fds_from_master(worker, &data); 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) { sendret._error = true; sendret._errno = errno; PERROR("setegid"); goto write_return; } } if (data.uid != prev_euid) { ret = seteuid(data.uid); if (ret < 0) { sendret._error = true; sendret._errno = errno; PERROR("seteuid"); goto write_return; } } /* * Also set umask to 0 for mkdir executable bit. */ umask(0); /* * Stage 3: Execute the command */ ret = (*cmd)(&data, &sendret); if (ret < 0) { DBG("Execution of command returned an error"); } write_return: ret = cleanup_received_fds(&data); 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 resulting file descriptors to the master. */ ret = send_fds_to_master(worker, data.cmd, &sendret); 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. */ } } ret = EXIT_SUCCESS; end: return ret; } static 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) { int ret = 0; 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)", (int) uid, (int) geteuid()); goto end; } } 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; } /* * Stage 2: Send file descriptor to the worker process if needed */ ret = send_fds_to_worker(worker, data); if (ret) { PERROR("do_send_fd error"); ret = -1; ret_value->_errno = EIO; goto end; } /* * Stage 3: Wait for the execution of the command */ /* * Stage 4: Receive the run_as_ret struct containing the return value and * errno */ 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; } 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_fds_from_worker(worker, cmd, ret_value); if (ret < 0) { 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; } end: 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 void run_as_destroy_worker_no_lock(void) { struct run_as_worker *worker = global_worker; DBG("Destroying run_as worker"); if (!worker) { return; } /* 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; } 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_no_lock(); /* 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) { return run_as_mkdirat_recursive(AT_FDCWD, path, mode, uid, gid); } LTTNG_HIDDEN int run_as_mkdirat_recursive(int dirfd, const char *path, mode_t mode, uid_t uid, gid_t gid) { int ret; struct run_as_data data = {}; struct run_as_ret run_as_ret = {}; DBG3("mkdirat() recursive fd = %d%s, path = %s, mode = %d, uid = %d, gid = %d", dirfd, dirfd == AT_FDCWD ? " (AT_FDCWD)" : "", path, (int) mode, (int) uid, (int) gid); ret = lttng_strncpy(data.u.mkdir.path, path, sizeof(data.u.mkdir.path)); if (ret) { ERR("Failed to copy path argument of mkdirat recursive command"); goto error; } data.u.mkdir.path[sizeof(data.u.mkdir.path) - 1] = '\0'; data.u.mkdir.mode = mode; data.u.mkdir.dirfd = dirfd; run_as(dirfd == AT_FDCWD ? RUN_AS_MKDIR_RECURSIVE : RUN_AS_MKDIRAT_RECURSIVE, &data, &run_as_ret, uid, gid); errno = run_as_ret._errno; ret = run_as_ret.u.ret; error: return ret; } LTTNG_HIDDEN int run_as_mkdir(const char *path, mode_t mode, uid_t uid, gid_t gid) { return run_as_mkdirat(AT_FDCWD, path, mode, uid, gid); } LTTNG_HIDDEN int run_as_mkdirat(int dirfd, const char *path, mode_t mode, uid_t uid, gid_t gid) { int ret; struct run_as_data data = {}; struct run_as_ret run_as_ret = {}; DBG3("mkdirat() recursive fd = %d%s, path = %s, mode = %d, uid = %d, gid = %d", dirfd, dirfd == AT_FDCWD ? " (AT_FDCWD)" : "", path, (int) mode, (int) uid, (int) gid); ret = lttng_strncpy(data.u.mkdir.path, path, sizeof(data.u.mkdir.path)); if (ret) { ERR("Failed to copy path argument of mkdirat command"); goto error; } data.u.mkdir.path[sizeof(data.u.mkdir.path) - 1] = '\0'; data.u.mkdir.mode = mode; data.u.mkdir.dirfd = dirfd; run_as(dirfd == AT_FDCWD ? RUN_AS_MKDIR : RUN_AS_MKDIRAT, &data, &run_as_ret, uid, gid); errno = run_as_ret._errno; ret = run_as_ret.u.ret; error: return ret; } LTTNG_HIDDEN int run_as_open(const char *path, int flags, mode_t mode, uid_t uid, gid_t gid) { return run_as_openat(AT_FDCWD, path, flags, mode, uid, gid); } LTTNG_HIDDEN int run_as_openat(int dirfd, const char *path, int flags, mode_t mode, uid_t uid, gid_t gid) { int ret; struct run_as_data data = {}; struct run_as_ret run_as_ret = {}; DBG3("openat() fd = %d%s, path = %s, flags = %X, mode = %d, uid %d, gid %d", dirfd, dirfd == AT_FDCWD ? " (AT_FDCWD)" : "", path, flags, (int) mode, (int) uid, (int) gid); ret = lttng_strncpy(data.u.open.path, path, sizeof(data.u.open.path)); if (ret) { ERR("Failed to copy path argument of open command"); goto error; } data.u.open.flags = flags; data.u.open.mode = mode; data.u.open.dirfd = dirfd; run_as(dirfd == AT_FDCWD ? RUN_AS_OPEN : RUN_AS_OPENAT, &data, &run_as_ret, uid, gid); errno = run_as_ret._errno; ret = run_as_ret.u.ret < 0 ? run_as_ret.u.ret : run_as_ret.u.open.fd; error: return ret; } LTTNG_HIDDEN int run_as_unlink(const char *path, uid_t uid, gid_t gid) { return run_as_unlinkat(AT_FDCWD, path, uid, gid); } LTTNG_HIDDEN int run_as_unlinkat(int dirfd, const char *path, uid_t uid, gid_t gid) { int ret; struct run_as_data data = {}; struct run_as_ret run_as_ret = {}; DBG3("unlinkat() fd = %d%s, path = %s, uid = %d, gid = %d", dirfd, dirfd == AT_FDCWD ? " (AT_FDCWD)" : "", path, (int) uid, (int) gid); ret = lttng_strncpy(data.u.unlink.path, path, sizeof(data.u.unlink.path)); if (ret) { goto error; } data.u.unlink.dirfd = dirfd; run_as(dirfd == AT_FDCWD ? RUN_AS_UNLINK : RUN_AS_UNLINKAT, &data, &run_as_ret, uid, gid); errno = run_as_ret._errno; ret = run_as_ret.u.ret; error: return ret; } LTTNG_HIDDEN int run_as_rmdir(const char *path, uid_t uid, gid_t gid) { return run_as_rmdirat(AT_FDCWD, path, uid, gid); } LTTNG_HIDDEN int run_as_rmdirat(int dirfd, const char *path, uid_t uid, gid_t gid) { int ret; struct run_as_data data = {}; struct run_as_ret run_as_ret = {}; DBG3("rmdirat() fd = %d%s, path = %s, uid = %d, gid = %d", dirfd, dirfd == AT_FDCWD ? " (AT_FDCWD)" : "", path, (int) uid, (int) gid); ret = lttng_strncpy(data.u.rmdir.path, path, sizeof(data.u.rmdir.path)); if (ret) { goto error; } data.u.rmdir.dirfd = dirfd; run_as(dirfd == AT_FDCWD ? RUN_AS_RMDIR : RUN_AS_RMDIRAT, &data, &run_as_ret, uid, gid); errno = run_as_ret._errno; ret = run_as_ret.u.ret; error: return ret; } LTTNG_HIDDEN int run_as_rmdir_recursive(const char *path, uid_t uid, gid_t gid, int flags) { return run_as_rmdirat_recursive(AT_FDCWD, path, uid, gid, flags); } LTTNG_HIDDEN int run_as_rmdirat_recursive(int dirfd, const char *path, uid_t uid, gid_t gid, int flags) { int ret; struct run_as_data data = {}; struct run_as_ret run_as_ret = {}; DBG3("rmdirat() recursive fd = %d%s, path = %s, uid = %d, gid = %d", dirfd, dirfd == AT_FDCWD ? " (AT_FDCWD)" : "", path, (int) uid, (int) gid); ret = lttng_strncpy(data.u.rmdir.path, path, sizeof(data.u.rmdir.path)); if (ret) { goto error; } data.u.rmdir.dirfd = dirfd; data.u.rmdir.flags = flags; run_as(dirfd == AT_FDCWD ? RUN_AS_RMDIR_RECURSIVE : RUN_AS_RMDIRAT_RECURSIVE, &data, &run_as_ret, uid, gid); errno = run_as_ret._errno; ret = run_as_ret.u.ret; error: return ret; } LTTNG_HIDDEN int run_as_rename(const char *old, const char *new, uid_t uid, gid_t gid) { return run_as_renameat(AT_FDCWD, old, AT_FDCWD, new, uid, gid); } LTTNG_HIDDEN int run_as_renameat(int old_dirfd, const char *old_name, int new_dirfd, const char *new_name, uid_t uid, gid_t gid) { int ret; struct run_as_data data = {}; struct run_as_ret run_as_ret = {}; DBG3("renameat() old_dirfd = %d%s, old_name = %s, new_dirfd = %d%s, new_name = %s, uid = %d, gid = %d", old_dirfd, old_dirfd == AT_FDCWD ? " (AT_FDCWD)" : "", old_name, new_dirfd, new_dirfd == AT_FDCWD ? " (AT_FDCWD)" : "", new_name, (int) uid, (int) gid); ret = lttng_strncpy(data.u.rename.old_path, old_name, sizeof(data.u.rename.old_path)); if (ret) { goto error; } ret = lttng_strncpy(data.u.rename.new_path, new_name, sizeof(data.u.rename.new_path)); if (ret) { goto error; } data.u.rename.dirfds[0] = old_dirfd; data.u.rename.dirfds[1] = new_dirfd; run_as(old_dirfd == AT_FDCWD && new_dirfd == AT_FDCWD ? RUN_AS_RENAME : RUN_AS_RENAMEAT, &data, &run_as_ret, uid, gid); errno = run_as_ret._errno; ret = run_as_ret.u.ret; error: return ret; } LTTNG_HIDDEN int run_as_extract_elf_symbol_offset(int fd, const char* function, uid_t uid, gid_t gid, uint64_t *offset) { int ret; struct run_as_data data = {}; struct run_as_ret run_as_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.u.extract_elf_symbol_offset.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'; ret = lttng_strncpy(data.u.extract_elf_symbol_offset.function, function, sizeof(data.u.extract_elf_symbol_offset.function)); if (ret) { goto error; } run_as(RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET, &data, &run_as_ret, uid, gid); errno = run_as_ret._errno; if (run_as_ret._error) { ret = -1; goto error; } *offset = run_as_ret.u.extract_elf_symbol_offset.offset; error: return ret; } 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) { int ret; struct run_as_data data = {}; struct run_as_ret run_as_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.u.extract_sdt_probe_offsets.fd = fd; ret = lttng_strncpy(data.u.extract_sdt_probe_offsets.probe_name, probe_name, sizeof(data.u.extract_sdt_probe_offsets.probe_name)); if (ret) { goto error; } ret = lttng_strncpy(data.u.extract_sdt_probe_offsets.provider_name, provider_name, sizeof(data.u.extract_sdt_probe_offsets.provider_name)); if (ret) { goto error; } run_as(RUN_AS_EXTRACT_SDT_PROBE_OFFSETS, &data, &run_as_ret, uid, gid); errno = run_as_ret._errno; if (run_as_ret._error) { ret = -1; goto error; } *num_offset = run_as_ret.u.extract_sdt_probe_offsets.num_offset; *offsets = zmalloc(*num_offset * sizeof(uint64_t)); if (!*offsets) { ret = -ENOMEM; goto error; } memcpy(*offsets, run_as_ret.u.extract_sdt_probe_offsets.offsets, *num_offset * sizeof(uint64_t)); error: return ret; } 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) { pthread_mutex_lock(&worker_lock); run_as_destroy_worker_no_lock(); pthread_mutex_unlock(&worker_lock); }