daemon_init() calls closeall() to close any "unneeded" file descriptors.
This causes the following issue with idmapd on systems that are
configured to have SSSD handle local users and groups:
1. During startup, rpc.idmapd calls getpwnam("nobody") and
getgrnam("nobody")
2. sss_nss_mc_get{pw,gr}nam from libnss_sss open the cache files for
users and groups and store the fd's in a struct sss_cli_mc_ctx. The
passwd cache is fd 3 and the group cache is fd 4.
3. idmapd calls daemon_init() which sets fd's 0, 1, and 2 to /dev/null
and fd 3 to the write end of the pipe that the child uses to report
it's startup status. It then closes all fd's >= 4.
4. idmapd then calls event_init() which leads to epoll_create1() which
returns 4 as the epoll fd.
6. An NFSv4 mount request comes in from a client, triggering an nfsdcb
callback.
7. idmapd calls getgrgid_r() which leads to a call to
sss_nss_check_header() which determines that the cache needs to be
reinitialized. sss_nss_mc_destroy_ctx() is called, which closes the
ctx->fd which now corresponds to the epoll file rather than the group
cache file.
8. event_dispatch() calls epoll_wait() with epfd=4, and -EBADF is
returned. idmapd logs the following error and exits with a nonzero
status:
rpc.idmapd[650]: main: event_dispatch returns errno 9 (Bad file descriptor)
Moving the deamon_init() call so that it happens before get{pw,gr}nam()
fixes this.
Signed-off-by: Scott Mayhew <smayhew@xxxxxxxxxx>
---
utils/idmapd/idmapd.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/utils/idmapd/idmapd.c b/utils/idmapd/idmapd.c
index c12e878..4cbe148 100644
--- a/utils/idmapd/idmapd.c
+++ b/utils/idmapd/idmapd.c
@@ -312,6 +312,8 @@ main(int argc, char **argv)
strncat(pipefsdir, "/nfs", sizeof(pipefsdir));
+ daemon_init(fg);
+
if ((pw = getpwnam(nobodyuser)) == NULL)
errx(1, "Could not find user \"%s\"", nobodyuser);
nobodyuid = pw->pw_uid;
@@ -328,8 +330,6 @@ main(int argc, char **argv)
if (nfs4_init_name_mapping(conf_path))
errx(1, "Unable to create name to user id mappings.");
- daemon_init(fg);
-
event_init();
if (verbose > 0)
--
2.9.4
--
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