| Message ID | 20170807190914.7422-1-smayhew@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 08/07/2017 03:09 PM, Scott Mayhew wrote: > 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@redhat.com> Committed... steved. > --- > 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) > -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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)
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@redhat.com> --- utils/idmapd/idmapd.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)