+++ /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 as published by the Free
- * Software Foundation; only version 2 of the License.
- *
- * 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., 59 Temple
- * Place - Suite 330, Boston, MA 02111-1307, 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/mman.h>
-
-#include <lttngerr.h>
-
-#include "runas.h"
-
-#define RUNAS_CHILD_STACK_SIZE 10485760
-
-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;
- char *p, tmp[PATH_MAX];
- struct stat statbuf;
- mode_t mode;
- size_t len;
- int ret;
-
- path = data->path;
- mode = data->mode;
-
- ret = snprintf(tmp, sizeof(tmp), "%s", path);
- 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 = '/';
- }
- }
-
- ret = mkdir(tmp, mode);
- if (ret < 0) {
- if (!(errno == EEXIST)) {
- PERROR("mkdir recursive last piece");
- ret = -errno;
- } else {
- ret = 0;
- }
- }
-
-error:
- return ret;
-}
-
-static
-int _mkdir(void *_data)
-{
- struct run_as_mkdir_data *data = _data;
- return mkdir(data->path, data->mode);
-}
-
-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)
-{
- struct run_as_data *data = _data;
- size_t writelen, writeleft, index;
- union {
- int i;
- char c[sizeof(int)];
- } sendret;
- int ret;
-
- /*
- * 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");
- return EXIT_FAILURE;
- }
- }
- if (data->uid != geteuid()) {
- ret = seteuid(data->uid);
- if (ret < 0) {
- perror("seteuid");
- return EXIT_FAILURE;
- }
- }
- /*
- * 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;
- }
- writeleft -= writelen;
- index += writelen;
- } while (writeleft > 0);
- return EXIT_SUCCESS;
-}
-
-static
-int run_as(int (*cmd)(void *data), void *data, 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;
-
- /*
- * 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");
- 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");
- ret = -ENOMEM;
- goto close_pipe;
- }
- /*
- * Pointing to the middle of the stack to support architectures
- * where the stack grows up (HPPA).
- */
- pid = clone(child_run_as, child_stack + (RUNAS_CHILD_STACK_SIZE / 2),
- CLONE_FILES | SIGCHLD,
- &run_as_data, NULL);
- if (pid < 0) {
- perror("clone");
- ret = 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.
- */
- pid = waitpid(pid, &status, 0);
- if (pid < 0 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) {
- perror("wait");
- ret = -1;
- }
-unmap_stack:
- ret = munmap(child_stack, RUNAS_CHILD_STACK_SIZE);
- if (ret < 0) {
- perror("munmap");
- }
-close_pipe:
- close(retval_pipe[0]);
- close(retval_pipe[1]);
-end:
- return retval.i;
-}
-
-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);
-}
-
-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.
- */
-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