selinux_child.c revision 8e44ddfccebe61728d8a2c1dafce36dfa944bc90
/*
SSSD
IPA back end -- set SELinux context in a child module
Authors:
Jakub Hrozek <jhrozek@redhat.com>
Copyright (C) 2014 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 <unistd.h>
#include <sys/stat.h>
#include <popt.h>
#include "util/util.h"
#include "util/child_common.h"
#include "providers/dp_backend.h"
struct input_buffer {
const char *seuser;
const char *mls_range;
const char *username;
};
static errno_t unpack_buffer(uint8_t *buf,
size_t size,
struct input_buffer *ibuf)
{
size_t p = 0;
uint32_t len;
/* seuser */
SAFEALIGN_COPY_UINT32_CHECK(&len, buf + p, size, &p);
DEBUG(SSSDBG_TRACE_INTERNAL, "seuser length: %d\n", len);
if (len == 0) {
return EINVAL;
} else {
if ((p + len ) > size) return EINVAL;
ibuf->seuser = talloc_strndup(ibuf, (char *)(buf + p), len);
if (ibuf->seuser == NULL) return ENOMEM;
DEBUG(SSSDBG_TRACE_INTERNAL, "seuser: %s\n", ibuf->seuser);
p += len;
}
/* MLS range */
SAFEALIGN_COPY_UINT32_CHECK(&len, buf + p, size, &p);
DEBUG(SSSDBG_TRACE_INTERNAL, "mls_range length: %d\n", len);
if (len == 0) {
return EINVAL;
} else {
if ((p + len ) > size) return EINVAL;
ibuf->mls_range = talloc_strndup(ibuf, (char *)(buf + p), len);
if (ibuf->mls_range == NULL) return ENOMEM;
DEBUG(SSSDBG_TRACE_INTERNAL, "mls_range: %s\n", ibuf->mls_range);
p += len;
}
/* username */
SAFEALIGN_COPY_UINT32_CHECK(&len, buf + p, size, &p);
DEBUG(SSSDBG_TRACE_INTERNAL, "username length: %d\n", len);
if (len == 0) {
return EINVAL;
} else {
if ((p + len ) > size) return EINVAL;
ibuf->username = talloc_strndup(ibuf, (char *)(buf + p), len);
if (ibuf->username == NULL) return ENOMEM;
DEBUG(SSSDBG_TRACE_INTERNAL, "username: %s\n", ibuf->username);
p += len;
}
return EOK;
}
static errno_t pack_buffer(struct response *r, int result)
{
size_t p = 0;
/* A buffer with the following structure must be created:
* uint32_t status of the request (required)
*/
r->size = sizeof(uint32_t);
r->buf = talloc_array(r, uint8_t, r->size);
if(r->buf == NULL) {
return ENOMEM;
}
DEBUG(SSSDBG_TRACE_FUNC, "result [%d]\n", result);
/* result */
SAFEALIGN_SET_UINT32(&r->buf[p], result, &p);
return EOK;
}
static errno_t prepare_response(TALLOC_CTX *mem_ctx,
int result,
struct response **rsp)
{
int ret;
struct response *r = NULL;
r = talloc_zero(mem_ctx, struct response);
if (r == NULL) {
return ENOMEM;
}
r->buf = NULL;
r->size = 0;
ret = pack_buffer(r, result);
if (ret != EOK) {
DEBUG(SSSDBG_CRIT_FAILURE, "pack_buffer failed\n");
return ret;
}
*rsp = r;
DEBUG(SSSDBG_TRACE_ALL, "r->size: %zu\n", r->size);
return EOK;
}
int main(int argc, const char *argv[])
{
int opt;
poptContext pc;
int debug_fd = -1;
errno_t ret;
TALLOC_CTX *main_ctx = NULL;
uint8_t *buf = NULL;
ssize_t len = 0;
struct input_buffer *ibuf = NULL;
struct response *resp = NULL;
ssize_t written;
struct poptOption long_options[] = {
POPT_AUTOHELP
{"debug-level", 'd', POPT_ARG_INT, &debug_level, 0,
_("Debug level"), NULL},
{"debug-timestamps", 0, POPT_ARG_INT, &debug_timestamps, 0,
_("Add debug timestamps"), NULL},
{"debug-microseconds", 0, POPT_ARG_INT, &debug_microseconds, 0,
_("Show timestamps with microseconds"), NULL},
{"debug-fd", 0, POPT_ARG_INT, &debug_fd, 0,
_("An open file descriptor for the debug logs"), NULL},
{"debug-to-stderr", 0, POPT_ARG_NONE | POPT_ARGFLAG_DOC_HIDDEN,
&debug_to_stderr, 0,
_("Send the debug output to stderr directly."), NULL },
POPT_TABLEEND
};
/* Set debug level to invalid value so we can decide if -d 0 was used. */
debug_level = SSSDBG_INVALID;
pc = poptGetContext(argv[0], argc, argv, long_options, 0);
while((opt = poptGetNextOpt(pc)) != -1) {
switch(opt) {
default:
fprintf(stderr, "\nInvalid option %s: %s\n\n",
poptBadOption(pc, 0), poptStrerror(opt));
poptPrintUsage(pc, stderr, 0);
_exit(-1);
}
}
poptFreeContext(pc);
DEBUG_INIT(debug_level);
debug_prg_name = talloc_asprintf(NULL, "[sssd[selinux_child[%d]]]", getpid());
if (debug_prg_name == NULL) {
DEBUG(SSSDBG_CRIT_FAILURE, "talloc_asprintf failed.\n");
goto fail;
}
if (debug_fd != -1) {
ret = set_debug_file_from_fd(debug_fd);
if (ret != EOK) {
DEBUG(SSSDBG_CRIT_FAILURE, "set_debug_file_from_fd failed.\n");
}
}
DEBUG(SSSDBG_TRACE_FUNC, "selinux_child started.\n");
DEBUG(SSSDBG_TRACE_INTERNAL,
"Running as [%"SPRIuid"][%"SPRIgid"].\n", geteuid(), getegid());
main_ctx = talloc_new(NULL);
if (main_ctx == NULL) {
DEBUG(SSSDBG_CRIT_FAILURE, "talloc_new failed.\n");
talloc_free(discard_const(debug_prg_name));
goto fail;
}
talloc_steal(main_ctx, debug_prg_name);
buf = talloc_size(main_ctx, sizeof(uint8_t)*IN_BUF_SIZE);
if (buf == NULL) {
DEBUG(SSSDBG_CRIT_FAILURE, "talloc_size failed.\n");
goto fail;
}
ibuf = talloc_zero(main_ctx, struct input_buffer);
if (ibuf == NULL) {
DEBUG(SSSDBG_CRIT_FAILURE, "talloc_zero failed.\n");
goto fail;
}
DEBUG(SSSDBG_TRACE_FUNC, "context initialized\n");
errno = 0;
len = sss_atomic_read_s(STDIN_FILENO, buf, IN_BUF_SIZE);
if (len == -1) {
ret = errno;
DEBUG(SSSDBG_CRIT_FAILURE, "read failed [%d][%s].\n", ret, strerror(ret));
goto fail;
}
close(STDIN_FILENO);
ret = unpack_buffer(buf, len, ibuf);
if (ret != EOK) {
DEBUG(SSSDBG_CRIT_FAILURE,
"unpack_buffer failed.[%d][%s].\n", ret, strerror(ret));
goto fail;
}
DEBUG(SSSDBG_TRACE_FUNC, "performing selinux operations\n");
ret = set_seuser(ibuf->username, ibuf->seuser, ibuf->mls_range);
if (ret != EOK) {
DEBUG(SSSDBG_CRIT_FAILURE, "Cannot set SELinux login context.\n");
goto fail;
}
ret = prepare_response(main_ctx, ret, &resp);
if (ret != EOK) {
DEBUG(SSSDBG_CRIT_FAILURE, "Failed to prepare response buffer.\n");
goto fail;
}
errno = 0;
written = sss_atomic_write_s(STDOUT_FILENO, resp->buf, resp->size);
if (written == -1) {
ret = errno;
DEBUG(SSSDBG_CRIT_FAILURE, "write failed [%d][%s].\n", ret,
strerror(ret));
goto fail;
}
if (written != resp->size) {
DEBUG(SSSDBG_CRIT_FAILURE, "Expected to write %zu bytes, wrote %zu\n",
resp->size, written);
goto fail;
}
DEBUG(SSSDBG_TRACE_FUNC, "selinux_child completed successfully\n");
close(STDOUT_FILENO);
talloc_free(main_ctx);
return EXIT_SUCCESS;
fail:
DEBUG(SSSDBG_CRIT_FAILURE, "selinux_child failed!\n");
close(STDOUT_FILENO);
talloc_free(main_ctx);
return EXIT_FAILURE;
}