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script.c
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script.c
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/* Copyright (c) 2010-2017 Dovecot authors, see the included COPYING file */
#include "lib.h"
#include "array.h"
#include "str.h"
#include "strescape.h"
#include "env-util.h"
#include "execv-const.h"
#include "write-full.h"
#include "restrict-access.h"
#include "master-interface.h"
#include "master-service.h"
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/socket.h>
#define SCRIPT_MAJOR_VERSION 3
#define SCRIPT_READ_TIMEOUT_SECS 10
static ARRAY_TYPE(const_string) exec_args;
static const char **accepted_envs;
static void script_verify_version(const char *line)
{
if (line == NULL ||
!version_string_verify(line, "script", SCRIPT_MAJOR_VERSION)) {
i_fatal("Client not compatible with this binary "
"(connecting to wrong socket?)");
}
}
static void
exec_child(struct master_service_connection *conn,
const char *const *args, const char *const *envs)
{
unsigned int i, socket_count;
if (dup2(conn->fd, STDIN_FILENO) < 0)
i_fatal("dup2() failed: %m");
if (dup2(conn->fd, STDOUT_FILENO) < 0)
i_fatal("dup2() failed: %m");
/* close all fds */
socket_count = master_service_get_socket_count(master_service);
for (i = 0; i < socket_count; i++) {
if (close(MASTER_LISTEN_FD_FIRST + i) < 0)
i_error("close(listener) failed: %m");
}
if (close(MASTER_STATUS_FD) < 0)
i_error("close(status) failed: %m");
if (close(conn->fd) < 0)
i_error("close(conn->fd) failed: %m");
for (; *args != NULL; args++) {
const char *arg = t_str_tabunescape(*args);
array_append(&exec_args, &arg, 1);
}
array_append_zero(&exec_args);
env_clean();
if (envs != NULL) {
for(; *envs != NULL; envs++)
env_put(*envs);
}
args = array_idx(&exec_args, 0);
execvp_const(args[0], args);
}
static bool client_exec_script(struct master_service_connection *conn)
{
ARRAY_TYPE(const_string) envs;
const char *const *args;
string_t *input;
void *buf;
size_t prev_size, scanpos;
bool header_complete = FALSE, noreply = FALSE;
ssize_t ret;
int status;
pid_t pid;
net_set_nonblock(conn->fd, FALSE);
input = buffer_create_dynamic(pool_datastack_create(), IO_BLOCK_SIZE);
/* Input contains:
VERSION .. <lf>
[alarm=<secs> <lf>]
"noreply" | "-" (or anything really) <lf>
arg 1 <lf>
arg 2 <lf>
...
<lf>
DATA
This is quite a horrible protocol. If alarm is specified, it MUST be
before "noreply". If "noreply" isn't given, something other string
(typically "-") must be given which is eaten away.
*/
alarm(SCRIPT_READ_TIMEOUT_SECS);
scanpos = 1;
while (!header_complete) {
const unsigned char *pos, *end;
prev_size = input->used;
buf = buffer_append_space_unsafe(input, IO_BLOCK_SIZE);
/* peek in socket input buffer */
ret = recv(conn->fd, buf, IO_BLOCK_SIZE, MSG_PEEK);
if (ret <= 0) {
buffer_set_used_size(input, prev_size);
if (strchr(str_c(input), '\n') != NULL)
script_verify_version(t_strcut(str_c(input), '\n'));
if (ret < 0)
i_fatal("recv(MSG_PEEK) failed: %m");
i_fatal("recv(MSG_PEEK) failed: disconnected");
}
/* scan for final \n\n */
pos = CONST_PTR_OFFSET(input->data, scanpos);
end = CONST_PTR_OFFSET(input->data, prev_size + ret);
for (; pos < end; pos++) {
if (pos[-1] == '\n' && pos[0] == '\n') {
header_complete = TRUE;
pos++;
break;
}
}
scanpos = pos - (const unsigned char *)input->data;
/* read data for real (up to and including \n\n) */
ret = recv(conn->fd, buf, scanpos-prev_size, 0);
if (prev_size+ret != scanpos) {
if (ret < 0)
i_fatal("recv() failed: %m");
if (ret == 0)
i_fatal("recv() failed: disconnected");
i_fatal("recv() failed: size of definitive recv() differs from peek");
}
buffer_set_used_size(input, scanpos);
}
alarm(0);
/* drop the last two LFs */
buffer_set_used_size(input, scanpos-2);
args = t_strsplit(str_c(input), "\n");
script_verify_version(*args); args++;
t_array_init(&envs, 16);
if (*args != NULL) {
const char *p;
if (strncmp(*args, "alarm=", 6) == 0) {
unsigned int seconds;
if (str_to_uint(*args + 6, &seconds) < 0)
i_fatal("invalid alarm option");
alarm(seconds);
args++;
}
while (strncmp(*args, "env_", 4) == 0) {
const char *envname, *env;
env = t_str_tabunescape(*args+4);
p = strchr(env, '=');
if (p == NULL)
i_fatal("invalid environment variable");
envname = t_strdup_until(*args+4, p);
if (str_array_find(accepted_envs, envname))
array_append(&envs, &env, 1);
args++;
}
if (strcmp(*args, "noreply") == 0) {
noreply = TRUE;
}
if (**args == '\0')
i_fatal("empty options");
args++;
}
array_append_zero(&envs);
if (noreply) {
/* no need to fork and check exit status */
exec_child(conn, args, array_idx(&envs, 0));
i_unreached();
}
if ((pid = fork()) == (pid_t)-1) {
i_error("fork() failed: %m");
return FALSE;
}
if (pid == 0) {
/* child */
exec_child(conn, args, array_idx(&envs, 0));
i_unreached();
}
/* parent */
/* check script exit status */
if (waitpid(pid, &status, 0) < 0) {
i_error("waitpid() failed: %m");
return FALSE;
} else if (WIFEXITED(status)) {
ret = WEXITSTATUS(status);
if (ret != 0) {
i_error("Script terminated abnormally, exit status %d", (int)ret);
return FALSE;
}
} else if (WIFSIGNALED(status)) {
i_error("Script terminated abnormally, signal %d", WTERMSIG(status));
return FALSE;
} else if (WIFSTOPPED(status)) {
i_fatal("Script stopped, signal %d", WSTOPSIG(status));
return FALSE;
} else {
i_fatal("Script terminated abnormally, return status %d", status);
return FALSE;
}
return TRUE;
}
static void client_connected(struct master_service_connection *conn)
{
char response[2];
response[0] = client_exec_script(conn) ? '+' : '-';
response[1] = '\n';
if (write_full(conn->fd, &response, 2) < 0)
i_error("write(response) failed: %m");
}
int main(int argc, char *argv[])
{
ARRAY_TYPE(const_string) aenvs;
const char *binary;
const char *const *envs;
int c, i;
master_service = master_service_init("script", 0, &argc, &argv, "+e:");
t_array_init(&aenvs, 16);
while ((c = master_getopt(master_service)) > 0) {
switch (c) {
case 'e':
envs = t_strsplit_spaces(optarg,", \t");
while (*envs != NULL) {
array_append(&aenvs, envs, 1);
envs++;
}
break;
default:
return FATAL_DEFAULT;
}
}
argc -= optind;
argv += optind;
array_append_zero(&aenvs);
accepted_envs = p_strarray_dup(default_pool, array_idx(&aenvs, 0));
master_service_init_log(master_service, "script: ");
if (argv[0] == NULL)
i_fatal("Missing script path");
restrict_access_by_env(NULL, FALSE);
restrict_access_allow_coredumps(TRUE);
master_service_init_finish(master_service);
master_service_set_service_count(master_service, 1);
if (argv[0][0] == '/')
binary = argv[0];
else
binary = t_strconcat(PKG_LIBEXECDIR"/", argv[0], NULL);
i_array_init(&exec_args, argc + 16);
array_append(&exec_args, &binary, 1);
for (i = 1; i < argc; i++) {
const char *arg = argv[i];
array_append(&exec_args, &arg, 1);
}
master_service_run(master_service, client_connected);
array_free(&exec_args);
i_free(accepted_envs);
master_service_deinit(&master_service);
return 0;
}