child_common.c revision c8a124ac1b03d83016bda02cad5a369ce6fb1cd7
/*
SSSD
Common helper functions to be used in child processes
Authors:
Sumit Bose <sbose@redhat.com>
Copyright (C) 2009 Red Hat
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; either version 3 of the License, or
(at your option) any later version.
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, see <http://www.gnu.org/licenses/>.
*/
#include <sys/types.h>
#include <fcntl.h>
#include <tevent.h>
#include <sys/wait.h>
#include <errno.h>
#include "util/util.h"
#include "util/find_uid.h"
#include "db/sysdb.h"
#include "util/child_common.h"
struct sss_sigchild_ctx {
struct tevent_context *ev;
hash_table_t *children;
int options;
};
struct sss_child_ctx {
pid_t pid;
sss_child_fn_t cb;
void *pvt;
struct sss_sigchild_ctx *sigchld_ctx;
};
errno_t sss_sigchld_init(TALLOC_CTX *mem_ctx,
struct tevent_context *ev,
struct sss_sigchild_ctx **child_ctx)
{
errno_t ret;
struct sss_sigchild_ctx *sigchld_ctx;
struct tevent_signal *tes;
sigchld_ctx = talloc_zero(mem_ctx, struct sss_sigchild_ctx);
if (!sigchld_ctx) {
DEBUG(0, ("fatal error initializing sss_sigchild_ctx\n"));
return ENOMEM;
}
sigchld_ctx->ev = ev;
ret = sss_hash_create(sigchld_ctx, 10, &sigchld_ctx->children);
if (ret != EOK) {
DEBUG(SSSDBG_FATAL_FAILURE,
("fatal error initializing children hash table: [%s]\n",
strerror(ret)));
talloc_free(sigchld_ctx);
return ret;
}
BlockSignals(false, SIGCHLD);
tes = tevent_add_signal(ev, sigchld_ctx, SIGCHLD, SA_SIGINFO,
sss_child_handler, sigchld_ctx);
if (tes == NULL) {
talloc_free(sigchld_ctx);
return EIO;
}
*child_ctx = sigchld_ctx;
return EOK;
}
static int sss_child_destructor(void *ptr)
{
struct sss_child_ctx *child_ctx;
hash_key_t key;
int error;
child_ctx = talloc_get_type(ptr, struct sss_child_ctx);
key.type = HASH_KEY_ULONG;
key.ul = child_ctx->pid;
error = hash_delete(child_ctx->sigchld_ctx->children, &key);
if (error != HASH_SUCCESS && error != HASH_ERROR_KEY_NOT_FOUND) {
DEBUG(SSSDBG_TRACE_INTERNAL,
("failed to delete child_ctx from hash table [%d]: %s\n",
error, hash_error_string(error)));
}
return 0;
}
errno_t sss_child_register(TALLOC_CTX *mem_ctx,
struct sss_sigchild_ctx *sigchld_ctx,
pid_t pid,
sss_child_fn_t cb,
void *pvt,
struct sss_child_ctx **child_ctx)
{
struct sss_child_ctx *child;
hash_key_t key;
hash_value_t value;
int error;
child = talloc_zero(mem_ctx, struct sss_child_ctx);
if (child == NULL) {
return ENOMEM;
}
child->pid = pid;
child->cb = cb;
child->pvt = pvt;
child->sigchld_ctx = sigchld_ctx;
key.type = HASH_KEY_ULONG;
key.ul = pid;
value.type = HASH_VALUE_PTR;
value.ptr = child;
error = hash_enter(sigchld_ctx->children, &key, &value);
if (error != HASH_SUCCESS) {
talloc_free(child);
return ENOMEM;
}
talloc_set_destructor((TALLOC_CTX *) child, sss_child_destructor);
*child_ctx = child;
return EOK;
}
struct sss_child_cb_pvt {
struct sss_child_ctx *child_ctx;
int wait_status;
};
static void sss_child_invoke_cb(struct tevent_context *ev,
struct tevent_immediate *imm,
void *pvt)
{
struct sss_child_cb_pvt *cb_pvt;
struct sss_child_ctx *child_ctx;
hash_key_t key;
int error;
cb_pvt = talloc_get_type(pvt, struct sss_child_cb_pvt);
child_ctx = cb_pvt->child_ctx;
key.type = HASH_KEY_ULONG;
key.ul = child_ctx->pid;
error = hash_delete(child_ctx->sigchld_ctx->children, &key);
if (error != HASH_SUCCESS && error != HASH_ERROR_KEY_NOT_FOUND) {
DEBUG(SSSDBG_OP_FAILURE,
("failed to delete child_ctx from hash table [%d]: %s\n",
error, hash_error_string(error)));
}
if (child_ctx->cb) {
child_ctx->cb(child_ctx->pid, cb_pvt->wait_status, child_ctx->pvt);
}
}
void sss_child_handler(struct tevent_context *ev,
struct tevent_signal *se,
int signum,
int count,
void *siginfo,
void *private_data)
{
struct sss_sigchild_ctx *sigchld_ctx;
struct tevent_immediate *imm;
struct sss_child_cb_pvt *invoke_pvt;
struct sss_child_ctx *child_ctx;
hash_key_t key;
hash_value_t value;
int error;
int wait_status;
pid_t pid;
sigchld_ctx = talloc_get_type(private_data, struct sss_sigchild_ctx);
key.type = HASH_KEY_ULONG;
do {
do {
errno = 0;
pid = waitpid(-1, &wait_status, WNOHANG | sigchld_ctx->options);
} while (pid == -1 && errno == EINTR);
if (pid == -1) {
DEBUG(SSSDBG_TRACE_INTERNAL,
("waitpid failed [%d]: %s\n", errno, strerror(errno)));
return;
} else if (pid == 0) continue;
key.ul = pid;
error = hash_lookup(sigchld_ctx->children, &key, &value);
if (error == HASH_SUCCESS) {
child_ctx = talloc_get_type(value.ptr, struct sss_child_ctx);
imm = tevent_create_immediate(sigchld_ctx->ev);
if (imm == NULL) {
DEBUG(SSSDBG_CRIT_FAILURE,
("Out of memory invoking SIGCHLD callback\n"));
return;
}
invoke_pvt = talloc_zero(child_ctx, struct sss_child_cb_pvt);
if (invoke_pvt == NULL) {
DEBUG(SSSDBG_CRIT_FAILURE,
("out of memory invoking SIGCHLD callback\n"));
return;
}
invoke_pvt->child_ctx = child_ctx;
invoke_pvt->wait_status = wait_status;
tevent_schedule_immediate(imm, sigchld_ctx->ev,
sss_child_invoke_cb, invoke_pvt);
} else if (error == HASH_ERROR_KEY_NOT_FOUND) {
DEBUG(SSSDBG_TRACE_LIBS,
("BUG: waitpid() returned [%d] but it was not in the table. "
"This could be due to a linked library creating processes "
"without registering them with the sigchld handler\n",
pid));
/* We will simply ignore this and return to the loop
* This will prevent a zombie, but may cause unexpected
* behavior in the code that was trying to handle this
* pid.
*/
} else {
DEBUG(SSSDBG_OP_FAILURE,
("SIGCHLD hash table error [%d]: %s\n",
error, hash_error_string(error)));
/* This is bad, but we should try to check for other
* children anyway, to avoid potential zombies.
*/
}
} while (pid != 0);
}
struct sss_child_ctx_old {
struct tevent_signal *sige;
pid_t pid;
int child_status;
sss_child_callback_t cb;
void *pvt;
};
int child_handler_setup(struct tevent_context *ev, int pid,
sss_child_callback_t cb, void *pvt)
{
struct sss_child_ctx_old *child_ctx;
DEBUG(8, ("Setting up signal handler up for pid [%d]\n", pid));
child_ctx = talloc_zero(ev, struct sss_child_ctx_old);
if (child_ctx == NULL) {
return ENOMEM;
}
child_ctx->sige = tevent_add_signal(ev, child_ctx, SIGCHLD, SA_SIGINFO,
child_sig_handler, child_ctx);
if(!child_ctx->sige) {
/* Error setting up signal handler */
talloc_free(child_ctx);
return ENOMEM;
}
child_ctx->pid = pid;
child_ctx->cb = cb;
child_ctx->pvt = pvt;
DEBUG(8, ("Signal handler set up for pid [%d]\n", pid));
return EOK;
}
/* Async communication with the child process via a pipe */
struct write_pipe_state {
int fd;
uint8_t *buf;
size_t len;
size_t written;
};
static void write_pipe_handler(struct tevent_context *ev,
struct tevent_fd *fde,
uint16_t flags, void *pvt);
struct tevent_req *write_pipe_send(TALLOC_CTX *mem_ctx,
struct tevent_context *ev,
uint8_t *buf, size_t len, int fd)
{
struct tevent_req *req;
struct write_pipe_state *state;
struct tevent_fd *fde;
req = tevent_req_create(mem_ctx, &state, struct write_pipe_state);
if (req == NULL) return NULL;
state->fd = fd;
state->buf = buf;
state->len = len;
state->written = 0;
fde = tevent_add_fd(ev, state, fd, TEVENT_FD_WRITE,
write_pipe_handler, req);
if (fde == NULL) {
DEBUG(1, ("tevent_add_fd failed.\n"));
goto fail;
}
return req;
fail:
talloc_zfree(req);
return NULL;
}
static void write_pipe_handler(struct tevent_context *ev,
struct tevent_fd *fde,
uint16_t flags, void *pvt)
{
struct tevent_req *req = talloc_get_type(pvt, struct tevent_req);
struct write_pipe_state *state = tevent_req_data(req,
struct write_pipe_state);
errno_t ret;
if (flags & TEVENT_FD_READ) {
DEBUG(SSSDBG_CRIT_FAILURE,
("write_pipe_done called with TEVENT_FD_READ,"
" this should not happen.\n"));
tevent_req_error(req, EINVAL);
return;
}
errno = 0;
state->written = sss_atomic_write_s(state->fd, state->buf, state->len);
if (state->written == -1) {
ret = errno;
DEBUG(SSSDBG_CRIT_FAILURE,
("write failed [%d][%s].\n", ret, strerror(ret)));
tevent_req_error(req, ret);
return;
}
if (state->len != state->written) {
DEBUG(SSSDBG_CRIT_FAILURE, ("Wrote %d bytes, expected %d\n",
state->written, state->len));
tevent_req_error(req, EIO);
return;
}
DEBUG(SSSDBG_TRACE_FUNC, ("All data has been sent!\n"));
tevent_req_done(req);
return;
}
int write_pipe_recv(struct tevent_req *req)
{
TEVENT_REQ_RETURN_ON_ERROR(req);
return EOK;
}
struct read_pipe_state {
int fd;
uint8_t *buf;
size_t len;
};
static void read_pipe_handler(struct tevent_context *ev,
struct tevent_fd *fde,
uint16_t flags, void *pvt);
struct tevent_req *read_pipe_send(TALLOC_CTX *mem_ctx,
struct tevent_context *ev, int fd)
{
struct tevent_req *req;
struct read_pipe_state *state;
struct tevent_fd *fde;
req = tevent_req_create(mem_ctx, &state, struct read_pipe_state);
if (req == NULL) return NULL;
state->fd = fd;
state->buf = NULL;
state->len = 0;
fde = tevent_add_fd(ev, state, fd, TEVENT_FD_READ,
read_pipe_handler, req);
if (fde == NULL) {
DEBUG(1, ("tevent_add_fd failed.\n"));
goto fail;
}
return req;
fail:
talloc_zfree(req);
return NULL;
}
static void read_pipe_handler(struct tevent_context *ev,
struct tevent_fd *fde,
uint16_t flags, void *pvt)
{
struct tevent_req *req = talloc_get_type(pvt, struct tevent_req);
struct read_pipe_state *state = tevent_req_data(req,
struct read_pipe_state);
ssize_t size;
errno_t err;
uint8_t buf[CHILD_MSG_CHUNK];
if (flags & TEVENT_FD_WRITE) {
DEBUG(1, ("read_pipe_done called with TEVENT_FD_WRITE,"
" this should not happen.\n"));
tevent_req_error(req, EINVAL);
return;
}
size = sss_atomic_read_s(state->fd,
buf,
CHILD_MSG_CHUNK);
if (size == -1) {
err = errno;
DEBUG(SSSDBG_CRIT_FAILURE,
("read failed [%d][%s].\n", err, strerror(err)));
tevent_req_error(req, err);
return;
} else if (size > 0) {
state->buf = talloc_realloc(state, state->buf, uint8_t,
state->len + size);
if(!state->buf) {
tevent_req_error(req, ENOMEM);
return;
}
safealign_memcpy(&state->buf[state->len], buf,
size, &state->len);
return;
} else if (size == 0) {
DEBUG(6, ("EOF received, client finished\n"));
tevent_req_done(req);
return;
} else {
DEBUG(1, ("unexpected return value of read [%d].\n", size));
tevent_req_error(req, EINVAL);
return;
}
}
int read_pipe_recv(struct tevent_req *req, TALLOC_CTX *mem_ctx,
uint8_t **buf, ssize_t *len)
{
struct read_pipe_state *state;
state = tevent_req_data(req, struct read_pipe_state);
TEVENT_REQ_RETURN_ON_ERROR(req);
*buf = talloc_steal(mem_ctx, state->buf);
*len = state->len;
return EOK;
}
/* The pipes to communicate with the child must be nonblocking */
void fd_nonblocking(int fd)
{
int flags;
int ret;
flags = fcntl(fd, F_GETFL, 0);
if (flags == -1) {
ret = errno;
DEBUG(1, ("F_GETFL failed [%d][%s].\n", ret, strerror(ret)));
return;
}
if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) == -1) {
ret = errno;
DEBUG(1, ("F_SETFL failed [%d][%s].\n", ret, strerror(ret)));
}
return;
}
static void child_invoke_callback(struct tevent_context *ev,
struct tevent_immediate *imm,
void *pvt);
void child_sig_handler(struct tevent_context *ev,
struct tevent_signal *sige, int signum,
int count, void *__siginfo, void *pvt)
{
int ret, err;
struct sss_child_ctx_old *child_ctx;
struct tevent_immediate *imm;
if (count <= 0) {
DEBUG(0, ("SIGCHLD handler called with invalid child count\n"));
return;
}
child_ctx = talloc_get_type(pvt, struct sss_child_ctx_old);
DEBUG(7, ("Waiting for child [%d].\n", child_ctx->pid));
errno = 0;
ret = waitpid(child_ctx->pid, &child_ctx->child_status, WNOHANG);
if (ret == -1) {
err = errno;
DEBUG(1, ("waitpid failed [%d][%s].\n", err, strerror(err)));
} else if (ret == 0) {
DEBUG(1, ("waitpid did not found a child with changed status.\n"));
} else {
if WIFEXITED(child_ctx->child_status) {
if (WEXITSTATUS(child_ctx->child_status) != 0) {
DEBUG(1, ("child [%d] failed with status [%d].\n", ret,
WEXITSTATUS(child_ctx->child_status)));
} else {
DEBUG(4, ("child [%d] finished successfully.\n", ret));
}
} else if WIFSIGNALED(child_ctx->child_status) {
DEBUG(1, ("child [%d] was terminated by signal [%d].\n", ret,
WTERMSIG(child_ctx->child_status)));
} else {
if WIFSTOPPED(child_ctx->child_status) {
DEBUG(7, ("child [%d] was stopped by signal [%d].\n", ret,
WSTOPSIG(child_ctx->child_status)));
}
if WIFCONTINUED(child_ctx->child_status) {
DEBUG(7, ("child [%d] was resumed by delivery of SIGCONT.\n",
ret));
}
return;
}
/* Invoke the callback in a tevent_immediate handler
* so that it is safe to free the tevent_signal *
*/
imm = tevent_create_immediate(ev);
if (imm == NULL) {
DEBUG(0, ("Out of memory invoking sig handler callback\n"));
return;
}
tevent_schedule_immediate(imm, ev,child_invoke_callback,
child_ctx);
}
return;
}
static void child_invoke_callback(struct tevent_context *ev,
struct tevent_immediate *imm,
void *pvt)
{
struct sss_child_ctx_old *child_ctx =
talloc_get_type(pvt, struct sss_child_ctx_old);
if (child_ctx->cb) {
child_ctx->cb(child_ctx->child_status, child_ctx->sige, child_ctx->pvt);
}
/* Stop monitoring for this child */
talloc_free(child_ctx);
}
static errno_t prepare_child_argv(TALLOC_CTX *mem_ctx,
int child_debug_fd,
const char *binary,
char ***_argv)
{
/*
* program name, debug_level, debug_timestamps,
* debug_microseconds and NULL
*/
uint_t argc = 5;
char ** argv;
errno_t ret = EINVAL;
/* Save the current state in case an interrupt changes it */
bool child_debug_to_file = debug_to_file;
bool child_debug_timestamps = debug_timestamps;
bool child_debug_microseconds = debug_microseconds;
if (child_debug_to_file) argc++;
/*
* program name, debug_level, debug_to_file, debug_timestamps,
* debug_microseconds and NULL
*/
argv = talloc_array(mem_ctx, char *, argc);
if (argv == NULL) {
DEBUG(1, ("talloc_array failed.\n"));
return ENOMEM;
}
argv[--argc] = NULL;
argv[--argc] = talloc_asprintf(argv, "--debug-level=%#.4x",
debug_level);
if (argv[argc] == NULL) {
ret = ENOMEM;
goto fail;
}
if (child_debug_to_file) {
argv[--argc] = talloc_asprintf(argv, "--debug-fd=%d",
child_debug_fd);
if (argv[argc] == NULL) {
ret = ENOMEM;
goto fail;
}
}
argv[--argc] = talloc_asprintf(argv, "--debug-timestamps=%d",
child_debug_timestamps);
if (argv[argc] == NULL) {
ret = ENOMEM;
goto fail;
}
argv[--argc] = talloc_asprintf(argv, "--debug-microseconds=%d",
child_debug_microseconds);
if (argv[argc] == NULL) {
ret = ENOMEM;
goto fail;
}
argv[--argc] = talloc_strdup(argv, binary);
if (argv[argc] == NULL) {
ret = ENOMEM;
goto fail;
}
if (argc != 0) {
ret = EINVAL;
goto fail;
}
*_argv = argv;
return EOK;
fail:
talloc_free(argv);
return ret;
}
errno_t exec_child(TALLOC_CTX *mem_ctx,
int *pipefd_to_child, int *pipefd_from_child,
const char *binary, int debug_fd)
{
int ret;
errno_t err;
char **argv;
close(pipefd_to_child[1]);
ret = dup2(pipefd_to_child[0], STDIN_FILENO);
if (ret == -1) {
err = errno;
DEBUG(1, ("dup2 failed [%d][%s].\n", err, strerror(err)));
return err;
}
close(pipefd_from_child[0]);
ret = dup2(pipefd_from_child[1], STDOUT_FILENO);
if (ret == -1) {
err = errno;
DEBUG(1, ("dup2 failed [%d][%s].\n", err, strerror(err)));
return err;
}
ret = prepare_child_argv(mem_ctx, debug_fd,
binary, &argv);
if (ret != EOK) {
DEBUG(1, ("prepare_child_argv.\n"));
return ret;
}
execv(binary, argv);
err = errno;
DEBUG(SSSDBG_OP_FAILURE, ("execv failed [%d][%s].\n", err, strerror(err)));
return err;
}
void child_cleanup(int readfd, int writefd)
{
int ret;
if (readfd != -1) {
ret = close(readfd);
if (ret != EOK) {
ret = errno;
DEBUG(1, ("close failed [%d][%s].\n", ret, strerror(ret)));
}
}
if (writefd != -1) {
ret = close(writefd);
if (ret != EOK) {
ret = errno;
DEBUG(1, ("close failed [%d][%s].\n", ret, strerror(ret)));
}
}
}