Make handle_child_* request public

I took the opportunity to move everything related to the handling of the
krb5_child into a separate file and cleaned the interfaces and related
structures a bit.

1 files changed, 12 insertions, 319 deletions

diff --git a/src/providers/krb5/krb5_auth.c b/src/providers/krb5/krb5_auth.c
index 80d8734a..9dc7a2c9 100644
--- a/src/providers/krb5/krb5_auth.c
+++ b/src/providers/krb5/krb5_auth.c
@@ -39,12 +39,6 @@
 #include "providers/krb5/krb5_auth.h"
 #include "providers/krb5/krb5_utils.h"
 
-#ifndef SSSD_LIBEXEC_PATH
-#error "SSSD_LIBEXEC_PATH not defined"
-#else
-#define KRB5_CHILD SSSD_LIBEXEC_PATH"/krb5_child"
-#endif
-
 static errno_t safe_remove_old_ccache_file(const char *old_ccache_file,
                                            const char *new_ccache_file)
 {
@@ -205,72 +199,6 @@ done:
     return ret;
 }
 
-errno_t create_send_buffer(struct krb5child_req *kr, struct io_buffer **io_buf)
-{
-    struct io_buffer *buf;
-    size_t rp;
-    const char *keytab;
-    uint32_t validate;
-
-    keytab = dp_opt_get_cstring(kr->krb5_ctx->opts, KRB5_KEYTAB);
-    if (keytab == NULL) {
-        DEBUG(1, ("Missing keytab option.\n"));
-        return EINVAL;
-    }
-
-    validate = dp_opt_get_bool(kr->krb5_ctx->opts, KRB5_VALIDATE) ? 1 : 0;
-
-    buf = talloc(kr, struct io_buffer);
-    if (buf == NULL) {
-        DEBUG(1, ("talloc failed.\n"));
-        return ENOMEM;
-    }
-
-    buf->size = 9*sizeof(uint32_t) + strlen(kr->upn) + strlen(kr->ccname) +
-                strlen(keytab) +
-                kr->pd->authtok_size;
-    if (kr->pd->cmd == SSS_PAM_CHAUTHTOK) {
-        buf->size += sizeof(uint32_t) + kr->pd->newauthtok_size;
-    }
-
-    buf->data = talloc_size(kr, buf->size);
-    if (buf->data == NULL) {
-        DEBUG(1, ("talloc_size failed.\n"));
-        talloc_free(buf);
-        return ENOMEM;
-    }
-
-    rp = 0;
-    SAFEALIGN_COPY_UINT32(&buf->data[rp], &kr->pd->cmd, &rp);
-    SAFEALIGN_COPY_UINT32(&buf->data[rp], &kr->uid, &rp);
-    SAFEALIGN_COPY_UINT32(&buf->data[rp], &kr->gid, &rp);
-    SAFEALIGN_COPY_UINT32(&buf->data[rp], &validate, &rp);
-    SAFEALIGN_COPY_UINT32(&buf->data[rp], &kr->is_offline, &rp);
-
-    SAFEALIGN_SET_UINT32(&buf->data[rp], strlen(kr->upn), &rp);
-    safealign_memcpy(&buf->data[rp], kr->upn, strlen(kr->upn), &rp);
-
-    SAFEALIGN_SET_UINT32(&buf->data[rp], strlen(kr->ccname), &rp);
-    safealign_memcpy(&buf->data[rp], kr->ccname, strlen(kr->ccname), &rp);
-
-    SAFEALIGN_SET_UINT32(&buf->data[rp], strlen(keytab), &rp);
-    safealign_memcpy(&buf->data[rp], keytab, strlen(keytab), &rp);
-
-    SAFEALIGN_COPY_UINT32(&buf->data[rp], &kr->pd->authtok_size, &rp);
-    safealign_memcpy(&buf->data[rp], kr->pd->authtok,
-                     kr->pd->authtok_size, &rp);
-
-    if (kr->pd->cmd == SSS_PAM_CHAUTHTOK) {
-        SAFEALIGN_COPY_UINT32(&buf->data[rp], &kr->pd->newauthtok_size, &rp);
-        safealign_memcpy(&buf->data[rp], kr->pd->newauthtok,
-                         kr->pd->newauthtok_size, &rp);
-    }
-
-    *io_buf = buf;
-
-    return EOK;
-}
-
 static struct krb5_ctx *get_krb5_ctx(struct be_req *be_req)
 {
     struct pam_data *pd;
@@ -305,7 +233,6 @@ static int krb5_cleanup(void *ptr)
 
     if (kr == NULL) return EOK;
 
-    child_cleanup(kr->read_from_child_fd, kr->write_to_child_fd);
     memset(kr, 0, sizeof(struct krb5child_req));
 
     return EOK;
@@ -321,10 +248,9 @@ errno_t krb5_setup(TALLOC_CTX *mem_ctx, struct pam_data *pd,
         DEBUG(1, ("talloc failed.\n"));
         return ENOMEM;
     }
-    kr->read_from_child_fd = -1;
-    kr->write_to_child_fd = -1;
     kr->is_offline = false;
     kr->active_ccache_present = true;
+    kr->run_as_user = true;
     talloc_set_destructor((TALLOC_CTX *) kr, krb5_cleanup);
 
     kr->pd = pd;
@@ -335,249 +261,6 @@ errno_t krb5_setup(TALLOC_CTX *mem_ctx, struct pam_data *pd,
     return EOK;
 }
 
-struct handle_child_state {
-    struct tevent_context *ev;
-    struct krb5child_req *kr;
-    uint8_t *buf;
-    ssize_t len;
-};
-
-static void krb5_child_timeout(struct tevent_context *ev,
-                               struct tevent_timer *te,
-                               struct timeval tv, void *pvt)
-{
-    struct tevent_req *req = talloc_get_type(pvt, struct tevent_req);
-    struct handle_child_state *state = tevent_req_data(req,
-                                                     struct handle_child_state);
-    struct krb5child_req *kr = state->kr;
-    int ret;
-
-    if (kr->timeout_handler == NULL) {
-        return;
-    }
-
-    DEBUG(9, ("timeout for child [%d] reached.\n", kr->child_pid));
-
-    ret = kill(kr->child_pid, SIGKILL);
-    if (ret == -1) {
-        DEBUG(1, ("kill failed [%d][%s].\n", errno, strerror(errno)));
-    }
-
-    tevent_req_error(req, ETIMEDOUT);
-}
-
-static errno_t activate_child_timeout_handler(struct tevent_req *req,
-                                              struct tevent_context *ev,
-                                              struct krb5child_req *kr)
-{
-    struct timeval tv;
-    struct handle_child_state *state = tevent_req_data(req,
-                                                     struct handle_child_state);
-
-    tv = tevent_timeval_current();
-    tv = tevent_timeval_add(&tv,
-                            dp_opt_get_int(kr->krb5_ctx->opts,
-                                           KRB5_AUTH_TIMEOUT),
-                            0);
-    kr->timeout_handler = tevent_add_timer(ev, state, tv,
-                                           krb5_child_timeout, req);
-    if (kr->timeout_handler == NULL) {
-        DEBUG(1, ("tevent_add_timer failed.\n"));
-        return ENOMEM;
-    }
-
-    return EOK;
-}
-
-static errno_t fork_child(struct tevent_req *req, struct tevent_context *ev,
-                          struct krb5child_req *kr)
-{
-    int pipefd_to_child[2];
-    int pipefd_from_child[2];
-    pid_t pid;
-    int ret;
-    errno_t err;
-
-    ret = pipe(pipefd_from_child);
-    if (ret == -1) {
-        err = errno;
-        DEBUG(1, ("pipe failed [%d][%s].\n", errno, strerror(errno)));
-        return err;
-    }
-    ret = pipe(pipefd_to_child);
-    if (ret == -1) {
-        err = errno;
-        DEBUG(1, ("pipe failed [%d][%s].\n", errno, strerror(errno)));
-        return err;
-    }
-
-    pid = fork();
-
-    if (pid == 0) { /* child */
-        /* We need to keep the root privileges to read the keytab file if
-         * validation is enabled, otherwise we can drop them here and run
-         * krb5_child with user privileges.
-         * If we are offline and want to create an empty ccache file. In this
-         * case we can drop the privileges, too. */
-        if (!dp_opt_get_bool(kr->krb5_ctx->opts, KRB5_VALIDATE) ||
-            kr->is_offline) {
-            ret = become_user(kr->uid, kr->gid);
-            if (ret != EOK) {
-                DEBUG(1, ("become_user failed.\n"));
-                return ret;
-            }
-        }
-
-        err = exec_child(kr,
-                         pipefd_to_child, pipefd_from_child,
-                         KRB5_CHILD, kr->krb5_ctx->child_debug_fd);
-        if (err != EOK) {
-            DEBUG(1, ("Could not exec LDAP child: [%d][%s].\n",
-                      err, strerror(err)));
-            return err;
-        }
-    } else if (pid > 0) { /* parent */
-        kr->child_pid = pid;
-        kr->read_from_child_fd = pipefd_from_child[0];
-        close(pipefd_from_child[1]);
-        kr->write_to_child_fd = pipefd_to_child[1];
-        close(pipefd_to_child[0]);
-        fd_nonblocking(kr->read_from_child_fd);
-        fd_nonblocking(kr->write_to_child_fd);
-
-        ret = child_handler_setup(ev, pid, NULL, NULL);
-        if (ret != EOK) {
-            DEBUG(1, ("Could not set up child signal handler\n"));
-            return ret;
-        }
-
-        err = activate_child_timeout_handler(req, ev, kr);
-        if (err != EOK) {
-            DEBUG(1, ("activate_child_timeout_handler failed.\n"));
-        }
-
-    } else { /* error */
-        err = errno;
-        DEBUG(1, ("fork failed [%d][%s].\n", errno, strerror(errno)));
-        return err;
-    }
-
-    return EOK;
-}
-
-static void handle_child_step(struct tevent_req *subreq);
-static void handle_child_done(struct tevent_req *subreq);
-
-static struct tevent_req *handle_child_send(TALLOC_CTX *mem_ctx,
-                                            struct tevent_context *ev,
-                                            struct krb5child_req *kr)
-{
-    struct tevent_req *req, *subreq;
-    struct handle_child_state *state;
-    struct io_buffer *buf;
-    int ret;
-
-    req = tevent_req_create(mem_ctx, &state, struct handle_child_state);
-    if (req == NULL) {
-        return NULL;
-    }
-
-    state->ev = ev;
-    state->kr = kr;
-    state->buf = NULL;
-    state->len = 0;
-
-    ret = create_send_buffer(kr, &buf);
-    if (ret != EOK) {
-        DEBUG(1, ("create_send_buffer failed.\n"));
-        goto fail;
-    }
-
-    ret = fork_child(req, ev, kr);
-    if (ret != EOK) {
-        DEBUG(1, ("fork_child failed.\n"));
-        goto fail;
-    }
-
-    subreq = write_pipe_send(state, ev, buf->data, buf->size,
-                             kr->write_to_child_fd);
-    if (!subreq) {
-        ret = ENOMEM;
-        goto fail;
-    }
-    tevent_req_set_callback(subreq, handle_child_step, req);
-
-    return req;
-
-fail:
-    tevent_req_error(req, ret);
-    tevent_req_post(req, ev);
-    return req;
-}
-
-static void handle_child_step(struct tevent_req *subreq)
-{
-    struct tevent_req *req = tevent_req_callback_data(subreq,
-                                                      struct tevent_req);
-    struct handle_child_state *state = tevent_req_data(req,
-                                                    struct handle_child_state);
-    int ret;
-
-    ret = write_pipe_recv(subreq);
-    talloc_zfree(subreq);
-    if (ret != EOK) {
-        tevent_req_error(req, ret);
-        return;
-    }
-
-    close(state->kr->write_to_child_fd);
-    state->kr->write_to_child_fd = -1;
-
-    subreq = read_pipe_send(state, state->ev, state->kr->read_from_child_fd);
-    if (!subreq) {
-        tevent_req_error(req, ENOMEM);
-        return;
-    }
-    tevent_req_set_callback(subreq, handle_child_done, req);
-}
-
-static void handle_child_done(struct tevent_req *subreq)
-{
-    struct tevent_req *req = tevent_req_callback_data(subreq,
-                                                      struct tevent_req);
-    struct handle_child_state *state = tevent_req_data(req,
-                                                    struct handle_child_state);
-    int ret;
-
-    ret = read_pipe_recv(subreq, state, &state->buf, &state->len);
-    talloc_zfree(subreq);
-    if (ret != EOK) {
-        tevent_req_error(req, ret);
-        return;
-    }
-
-    close(state->kr->read_from_child_fd);
-    state->kr->read_from_child_fd = -1;
-
-    tevent_req_done(req);
-    return;
-}
-
-static int handle_child_recv(struct tevent_req *req,
-                             TALLOC_CTX *mem_ctx,
-                             uint8_t **buf, ssize_t *len)
-{
-    struct handle_child_state *state = tevent_req_data(req,
-                                                    struct handle_child_state);
-
-    TEVENT_REQ_RETURN_ON_ERROR(req);
-
-    *buf = talloc_move(mem_ctx, &state->buf);
-    *len = state->len;
-
-    return EOK;
-}
-
 static void krb5_resolve_kdc_done(struct tevent_req *subreq);
 static void krb5_resolve_kpasswd_done(struct tevent_req *subreq);
 static void krb5_find_ccache_step(struct tevent_req *req);
@@ -957,6 +640,17 @@ static void krb5_find_ccache_step(struct tevent_req *req)
         }
     }
 
+    /* We need to keep the root privileges to read the keytab file if
+     * validation is enabled, otherwise we can drop them and run krb5_child
+     * with user privileges.
+     * If we are offline we want to create an empty ccache file. In this
+     * case we can drop the privileges, too. */
+    if (!dp_opt_get_bool(kr->krb5_ctx->opts, KRB5_VALIDATE) || kr->is_offline) {
+        kr->run_as_user = true;
+    } else {
+        kr->run_as_user = false;
+    }
+
     subreq = handle_child_send(state, state->ev, kr);
     if (subreq == NULL) {
         DEBUG(1, ("handle_child_send failed.\n"));
@@ -996,7 +690,6 @@ static void krb5_child_done(struct tevent_req *subreq)
     int32_t msg_len;
 
     ret = handle_child_recv(subreq, pd, &buf, &len);
-    talloc_zfree(kr->timeout_handler);
     talloc_zfree(subreq);
     if (ret != EOK) {
         DEBUG(1, ("child failed (%d [%s])\n", ret, strerror(ret)));