+++ /dev/null
-/*
- * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
- * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * 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 _GNU_SOURCE
-#include <errno.h>
-#include <limits.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/wait.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <unistd.h>
-#include <fcntl.h>
-#include <sched.h>
-#include <sys/signal.h>
-
-#include <common/common.h>
-#include <common/utils.h>
-#include <common/compat/mman.h>
-#include <common/compat/clone.h>
-
-#include "runas.h"
-
-#define RUNAS_CHILD_STACK_SIZE 10485760
-
-#ifndef MAP_STACK
-#define MAP_STACK 0
-#endif
-
-#ifdef __FreeBSD__
-/* FreeBSD MAP_STACK always return -ENOMEM */
-#define LTTNG_MAP_STACK 0
-#else
-#define LTTNG_MAP_STACK MAP_STACK
-#endif
-
-#ifndef MAP_GROWSDOWN
-#define MAP_GROWSDOWN 0
-#endif
-
-#ifndef MAP_ANONYMOUS
-#define MAP_ANONYMOUS MAP_ANON
-#endif
-
-struct run_as_data {
- int (*cmd)(void *data);
- void *data;
- uid_t uid;
- gid_t gid;
- int retval_pipe;
-};
-
-struct run_as_mkdir_data {
- const char *path;
- mode_t mode;
-};
-
-struct run_as_open_data {
- const char *path;
- int flags;
- mode_t mode;
-};
-
-/*
- * Create recursively directory using the FULL path.
- */
-static
-int _mkdir_recursive(void *_data)
-{
- struct run_as_mkdir_data *data = _data;
- const char *path;
- mode_t mode;
-
- path = data->path;
- mode = data->mode;
-
- return utils_mkdir_recursive(path, mode);
-}
-
-static
-int _mkdir(void *_data)
-{
- int ret;
- struct run_as_mkdir_data *data = _data;
-
- ret = mkdir(data->path, data->mode);
- if (ret < 0) {
- ret = -errno;
- }
-
- return ret;
-}
-
-static
-int _open(void *_data)
-{
- struct run_as_open_data *data = _data;
- return open(data->path, data->flags, data->mode);
-}
-
-static
-int child_run_as(void *_data)
-{
- int ret;
- struct run_as_data *data = _data;
- ssize_t writelen;
- int sendret;
-
- /*
- * 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.
- */
- if (data->gid != getegid()) {
- ret = setegid(data->gid);
- if (ret < 0) {
- PERROR("setegid");
- sendret = -1;
- goto write_return;
- }
- }
- if (data->uid != geteuid()) {
- ret = seteuid(data->uid);
- if (ret < 0) {
- PERROR("seteuid");
- sendret = -1;
- goto write_return;
- }
- }
- /*
- * Also set umask to 0 for mkdir executable bit.
- */
- umask(0);
- sendret = (*data->cmd)(data->data);
-
-write_return:
- /* send back return value */
- writelen = lttng_write(data->retval_pipe, &sendret, sizeof(sendret));
- if (writelen < sizeof(sendret)) {
- PERROR("lttng_write error");
- return EXIT_FAILURE;
- } else {
- return EXIT_SUCCESS;
- }
-}
-
-static
-int run_as_clone(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid)
-{
- struct run_as_data run_as_data;
- int ret = 0;
- ssize_t readlen;
- int status;
- pid_t pid;
- int retval_pipe[2];
- void *child_stack;
- int retval;
-
- /*
- * If we are non-root, we can only deal with our own uid.
- */
- if (geteuid() != 0) {
- if (uid != geteuid()) {
- ERR("Client (%d)/Server (%d) UID mismatch (and sessiond is not root)",
- uid, geteuid());
- return -EPERM;
- }
- }
-
- ret = pipe(retval_pipe);
- if (ret < 0) {
- PERROR("pipe");
- retval = ret;
- 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 | LTTNG_MAP_STACK,
- -1, 0);
- if (child_stack == MAP_FAILED) {
- PERROR("mmap");
- retval = -ENOMEM;
- goto close_pipe;
- }
- /*
- * Pointing to the middle of the stack to support architectures
- * where the stack grows up (HPPA).
- */
- pid = lttng_clone_files(child_run_as, child_stack + (RUNAS_CHILD_STACK_SIZE / 2),
- &run_as_data);
- if (pid < 0) {
- PERROR("clone");
- retval = pid;
- goto unmap_stack;
- }
- /* receive return value */
- readlen = lttng_read(retval_pipe[0], &retval, sizeof(retval));
- if (readlen < sizeof(retval)) {
- ret = -1;
- }
-
- /*
- * Parent: wait for child to return, in which case the
- * shared memory map will have been created.
- */
- pid = waitpid(pid, &status, 0);
- if (pid < 0 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) {
- PERROR("wait");
- retval = -1;
- }
-unmap_stack:
- ret = munmap(child_stack, RUNAS_CHILD_STACK_SIZE);
- if (ret < 0) {
- PERROR("munmap");
- retval = ret;
- }
-close_pipe:
- ret = close(retval_pipe[0]);
- if (ret) {
- PERROR("close");
- }
- ret = close(retval_pipe[1]);
- if (ret) {
- PERROR("close");
- }
-end:
- return retval;
-}
-
-/*
- * To be used on setups where gdb has issues debugging programs using
- * clone/rfork. Note that this is for debuging ONLY, and should not be
- * considered secure.
- */
-static
-int run_as_noclone(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid)
-{
- int ret;
- mode_t old_mask;
-
- old_mask = umask(0);
- ret = cmd(data);
- umask(old_mask);
-
- return ret;
-}
-
-static
-int run_as(int (*cmd)(void *data), void *data, uid_t uid, gid_t gid)
-{
- if (!getenv("LTTNG_DEBUG_NOCLONE")) {
- int ret;
-
- DBG("Using run_as_clone");
- pthread_mutex_lock(<tng_libc_state_lock);
- ret = run_as_clone(cmd, data, uid, gid);
- pthread_mutex_unlock(<tng_libc_state_lock);
- return ret;
- } else {
- DBG("Using run_as_noclone");
- return run_as_noclone(cmd, data, uid, gid);
- }
-}
-
-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;
-
- 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);
-}
-
-LTTNG_HIDDEN
-int run_as_mkdir(const char *path, mode_t mode, uid_t uid, gid_t gid)
-{
- struct run_as_mkdir_data data;
-
- 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);
-}
-
-/*
- * 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;
-
- 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);
-}
projects / lttng-tools.git / blobdiff