mail-process.c revision b75aa058233423af13c2d3a8ddc725884b7ffbc5
/* Copyright (C) 2002 Timo Sirainen */
#include "common.h"
#include "fd-close-on-exec.h"
#include "env-util.h"
#include "str.h"
#include "network.h"
#include "restrict-access.h"
#include "restrict-process-size.h"
#include "var-expand.h"
#include "mail-process.h"
#include <stdlib.h>
#include <unistd.h>
#include <grp.h>
#include <syslog.h>
#include <sys/stat.h>
static unsigned int mail_process_count = 0;
static int validate_uid_gid(uid_t uid, gid_t gid, const char *user)
{
if (uid == 0) {
i_error("Logins with UID 0 not permitted (user %s)", user);
return FALSE;
}
if (uid < (uid_t)set->first_valid_uid ||
(set->last_valid_uid != 0 && uid > (uid_t)set->last_valid_uid)) {
i_error("Logins with UID %s (user %s) not permitted "
"(modify first_valid_uid in config file)",
dec2str(uid), user);
return FALSE;
}
if (gid < (gid_t)set->first_valid_gid ||
(set->last_valid_gid != 0 && gid > (gid_t)set->last_valid_gid)) {
i_error("Logins for users with primary group ID %s (user %s) "
"not permitted (see first_valid_gid in config file).",
dec2str(gid), user);
return FALSE;
}
return TRUE;
}
static int validate_chroot(const char *dir)
{
const char *const *chroot_dirs;
if (*dir == '\0')
return FALSE;
if (set->valid_chroot_dirs == NULL)
return FALSE;
chroot_dirs = t_strsplit(set->valid_chroot_dirs, ":");
while (*chroot_dirs != NULL) {
if (**chroot_dirs != '\0' &&
strncmp(dir, *chroot_dirs, strlen(*chroot_dirs)) == 0)
return TRUE;
chroot_dirs++;
}
return FALSE;
}
static const char *expand_mail_env(const char *env, const char *user,
const char *home)
{
string_t *str;
const char *p;
str = t_str_new(256);
/* it's either type:data or just data */
p = strchr(env, ':');
if (p != NULL) {
while (env != p) {
str_append_c(str, *env);
env++;
}
str_append_c(str, *env++);
}
if (env[0] == '~' && env[1] == '/') {
/* expand home */
str_append(str, home);
env++;
}
/* expand %vars */
var_expand(str, env, user, home);
return str_c(str);
}
int create_mail_process(int socket, struct ip_addr *ip,
const char *executable, const char *module_dir,
unsigned int process_size, int process_type,
struct auth_master_reply *reply, const char *data)
{
static const char *argv[] = { NULL, NULL, NULL };
const char *addr, *mail, *chroot_dir, *home_dir, *full_home_dir;
char title[1024];
pid_t pid;
int i, err;
if (mail_process_count == set->max_mail_processes) {
i_error("Maximum number of mail processes exceeded");
return FALSE;
}
if (!validate_uid_gid(reply->uid, reply->gid,
data + reply->virtual_user_idx))
return FALSE;
home_dir = data + reply->home_idx;
chroot_dir = data + reply->chroot_idx;
if (*chroot_dir != '\0' && !validate_chroot(chroot_dir)) {
i_error("Invalid chroot directory: %s", chroot_dir);
return FALSE;
}
pid = fork();
if (pid < 0) {
i_error("fork() failed: %m");
return FALSE;
}
if (pid != 0) {
/* master */
mail_process_count++;
PID_ADD_PROCESS_TYPE(pid, process_type);
return TRUE;
}
child_process_init_env();
/* move the client socket into stdin and stdout fds */
fd_close_on_exec(socket, FALSE);
if (dup2(socket, 0) < 0)
i_fatal("mail: dup2(stdin) failed: %m");
if (dup2(socket, 1) < 0)
i_fatal("mail: dup2(stdout) failed: %m");
if (close(socket) < 0)
i_error("mail: close(mail client) failed: %m");
/* setup environment - set the most important environment first
(paranoia about filling up environment without noticing) */
restrict_access_set_env(data + reply->system_user_idx,
reply->uid, reply->gid, chroot_dir,
set->first_valid_gid, set->last_valid_gid);
restrict_process_size(process_size, (unsigned int)-1);
if (*home_dir != '\0') {
full_home_dir = *chroot_dir == '\0' ? home_dir :
t_strconcat(chroot_dir, "/", home_dir, NULL);
if (chdir(full_home_dir) < 0)
i_fatal("chdir(%s) failed: %m", full_home_dir);
}
env_put("LOGGED_IN=1");
env_put(t_strconcat("HOME=", home_dir, NULL));
env_put(t_strconcat("MAIL_CACHE_FIELDS=",
set->mail_cache_fields, NULL));
env_put(t_strconcat("MAIL_NEVER_CACHE_FIELDS=",
set->mail_never_cache_fields, NULL));
env_put(t_strdup_printf("MAILBOX_CHECK_INTERVAL=%u",
set->mailbox_check_interval));
env_put(t_strdup_printf("MAILBOX_IDLE_CHECK_INTERVAL=%u",
set->mailbox_idle_check_interval));
env_put(t_strconcat("CLIENT_WORKAROUNDS=",
set->client_workarounds, NULL));
env_put(t_strdup_printf("MAIL_MAX_FLAG_LENGTH=%u",
set->mail_max_flag_length));
env_put(t_strdup_printf("IMAP_MAX_LINE_LENGTH=%u",
set->imap_max_line_length));
if (set->mail_save_crlf)
env_put("MAIL_SAVE_CRLF=1");
if (set->mail_read_mmaped)
env_put("MAIL_READ_MMAPED=1");
if (set->maildir_copy_with_hardlinks)
env_put("MAILDIR_COPY_WITH_HARDLINKS=1");
if (set->maildir_check_content_changes)
env_put("MAILDIR_CHECK_CONTENT_CHANGES=1");
if (set->mail_full_filesystem_access)
env_put("FULL_FILESYSTEM_ACCESS=1");
(void)umask(set->umask);
env_put(t_strconcat("MBOX_LOCKS=", set->mbox_locks, NULL));
env_put(t_strdup_printf("MBOX_LOCK_TIMEOUT=%u",
set->mbox_lock_timeout));
env_put(t_strdup_printf("MBOX_DOTLOCK_CHANGE_TIMEOUT=%u",
set->mbox_dotlock_change_timeout));
if (set->mbox_read_dotlock)
env_put("MBOX_READ_DOTLOCK=1");
if (module_dir != NULL && *module_dir != '\0')
env_put(t_strconcat("MODULE_DIR=", module_dir, NULL));
/* user given environment - may be malicious. virtual_user comes from
auth process, but don't trust that too much either. Some auth
mechanism might allow leaving extra data there. */
mail = data + reply->mail_idx;
if (*mail == '\0' && set->default_mail_env != NULL) {
mail = expand_mail_env(set->default_mail_env,
data + reply->virtual_user_idx,
home_dir);
}
env_put(t_strconcat("MAIL=", mail, NULL));
env_put(t_strconcat("USER=", data + reply->virtual_user_idx, NULL));
addr = net_ip2addr(ip);
env_put(t_strconcat("IP=", addr, NULL));
if (set->verbose_proctitle) {
if (addr == NULL)
addr = "??";
i_snprintf(title, sizeof(title), "[%s %s]",
data + reply->virtual_user_idx, addr);
argv[1] = title;
}
/* make sure we don't leak syslog fd, but do it last so that
any errors above will be logged */
closelog();
if (set->mail_drop_priv_before_exec)
restrict_access_by_env(TRUE);
/* hide the path, it's ugly */
argv[0] = strrchr(executable, '/');
if (argv[0] == NULL) argv[0] = executable; else argv[0]++;
execv(executable, (char **) argv);
err = errno;
for (i = 0; i < 3; i++)
(void)close(i);
i_fatal_status(FATAL_EXEC, "execv(%s) failed: %m", executable);
/* not reached */
return FALSE;
}
void mail_process_destroyed(pid_t pid __attr_unused__)
{
mail_process_count--;
}