On Tue, 17 May 2011 21:06:53 -0500 Shirish Pargaonkar <[email protected]> wrote:
> On Tue, May 17, 2011 at 11:09 AM, Jeff Layton <[email protected]> wrote: > > On Fri, 6 May 2011 02:33:59 -0500 > > [email protected] wrote: > > > >> From: Shirish Pargaonkar <[email protected]> > >> > >> Handle cifs.idmap type of key. Extract a SID string from the description > >> and map it to either an uid or gid using winbind APIs. > >> If that fails (e.g. because winbind is not installed/running or winbind > >> returns > >> an error), try to obtain uid of 'nobody' and gid of 'nogroup'. > >> And if that fails, kernel assigns uid and gid (from mount superblock). > >> > >> Enable including winbind header files and idmapping code conditional > >> to winbind devel rpms (header and library). > >> > >> An entry such as this > >> > >> create cifs.idmap * * /usr/sbin/cifs.idmap %k > >> > >> is needed in the file /etc/request-key.conf. > >> > >> > >> Signed-off-by: Shirish Pargaonkar <[email protected]> > >> --- > >> Makefile.am | 8 ++ > >> cifs.idmap.c | 215 > >> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > >> configure.ac | 58 +++++++++++++++- > >> 3 files changed, 280 insertions(+), 1 deletions(-) > >> create mode 100644 cifs.idmap.c > >> > >> diff --git a/Makefile.am b/Makefile.am > >> index 67a0190..ad33914 100644 > >> --- a/Makefile.am > >> +++ b/Makefile.am > >> @@ -30,3 +30,11 @@ bin_PROGRAMS = cifscreds > >> cifscreds_SOURCES = cifscreds.c resolve_host.c util.c > >> cifscreds_LDADD = -lkeyutils > >> endif > >> + > >> +if CONFIG_CIFSIDMAP > >> +cifs_idmap_sbindir = /usr/local/sbin > > > > ^^^^^^^^^ > > That looks wrong. If I configure with --prefix=/usr then this is still > > going to go in /usr/local/sbin, right? I think you instead want to > > append cifs.idmap to sbin_PROGRAMS. > > > >> +cifs_idmap_sbin_PROGRAMS = cifs.idmap > >> +cifs_idmap_SOURCES = cifs.idmap.c > >> +cifs_idmap_LDADD = -lkeyutils $(WINB_LDADD) > >> +endif > >> + > >> diff --git a/cifs.idmap.c b/cifs.idmap.c > >> new file mode 100644 > >> index 0000000..0f76873 > >> --- /dev/null > >> +++ b/cifs.idmap.c > >> @@ -0,0 +1,215 @@ > >> +/* > >> +* CIFS idmap helper. > >> +* Copyright (C) Shirish Pargaonkar ([email protected]) 2011 > >> +* > >> +* Used by /sbin/request-key.conf for handling > >> +* cifs upcall for SID to uig/gid and uid/gid to SID mapping. > >> +* You should have keyutils installed and add > >> +* this lines to /etc/request-key.conf file: > >> + > >> + create cifs.idmap * * /usr/local/sbin/cifs.idmap %k > >> + > >> +* 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 2 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, write to the Free Software > >> +* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA > >> +*/ > >> + > >> +#ifdef HAVE_CONFIG_H > >> +#include "config.h" > >> +#endif /* HAVE_CONFIG_H */ > >> + > >> +#include <string.h> > >> +#include <getopt.h> > >> +#include <syslog.h> > >> +#include <dirent.h> > >> +#include <sys/types.h> > >> +#include <sys/stat.h> > >> +#include <unistd.h> > >> +#ifdef HAVE_KEYUTILS_H > >> +#include <keyutils.h> > >> +#endif /* HAVE_KEYUTILS_H */ > > ^^^^^^^^^^ > > This can't be built w/o keyutils, right? So I don't think we need the > > #ifdefs. > > > >> +#include <stdint.h> > >> +#include <stdbool.h> > >> +#include <stdio.h> > >> +#include <stdlib.h> > >> +#include <errno.h> > >> +#include <limits.h> > >> +#ifdef HAVE_WBCLIENT_H > >> +#include <wbclient.h> > >> +#endif /* HAVE_WBCLIENT_H */ > >> + > >> +static const char *prog = "cifs.idmap"; > >> + > >> +static void usage(void) > >> +{ > >> + syslog(LOG_INFO, "Usage: %s [-t] [-v] [-l] key_serial", prog); > >> + fprintf(stderr, "Usage: %s [-t] [-v] [-l] key_serial\n", prog); > >> +} > >> + > >> +#ifdef HAVE_LIBWBCLIENT > >> +static int > >> +cifs_idmap(const key_serial_t key, const char *key_descr) > >> +{ > >> + int i; > >> + uid_t uid = 0; > >> + gid_t gid = 0;; > >> + wbcErr rc = 1; > >> + const char *keyend = key_descr; > >> + struct wbcDomainSid sid; > >> + struct passwd *pw; > >> + struct group *gr; > >> + > >> + /* skip next 4 ';' delimiters to get to description */ > >> + for (i = 1; i <= 4; ++i) { > >> + keyend = index(keyend + 1, ';'); > >> + if (!keyend) { > >> + syslog(LOG_ERR, "invalid key description: %s", > >> + key_descr); > >> + return 1; > >> + } > >> + } > >> + keyend++; > >> + > > > > No real bounds checking here. It seems unlikely, but a buggy kernel > > could send a garbled string and you could walk off the end of it here. > > > >> + /* > >> + * Use winbind to convert received string to a SID and lookup > >> + * name and map that SID to an uid. If either of these > >> + * function calls return with an error, use system calls to obtain > >> + * uid of user "nobody". If winbind fails to map a SID to an UID > >> + * and there is no user named "nobody", return error to the > >> + * upcall caller. Otherwise instanticate a key using that uid. > >> + * > >> + * The same applies to SID and gid mapping. Instead of a > >> + * user "nobody", user "nogroup" is looked up if winbind > >> + * fails to map a SID to a gid. > >> + */ > >> + if (strncmp(keyend, "os", 2) == 0) { > >> + keyend = index(keyend + 1, ':'); > >> + keyend++; > > ^^^^^^^^^ > > ditto on the bounds checks > > > >> + rc = wbcStringToSid(keyend, &sid); > >> + if (rc) > >> + syslog(LOG_DEBUG, "O strtosid: %s, rc: %d", keyend, > >> rc); > >> + else { > >> + rc = wbcSidToUid(&sid, &uid); > >> + if (rc) > >> + syslog(LOG_DEBUG, "SID %s to uid wbc error: > >> %d", > >> + keyend, rc); > >> + } > >> + if (rc) { /* either of the two wbcSid functions failed */ > >> + pw = getpwnam("nobody"); > >> + if (!pw) > >> + syslog(LOG_DEBUG, "SID %s to uid pw error: > >> %d", > >> + keyend, rc); > >> + else { > >> + uid = pw->pw_uid; > >> + rc = 0; > >> + } > >> + } > >> + if (!rc) { /* SID has been mapped to a uid */ > >> + rc = keyctl_instantiate(key, &uid, sizeof(uid_t), 0); > >> + if (rc) > >> + syslog(LOG_ERR, "%s: key inst: %s", > >> + __func__, strerror(errno)); > >> + } > >> + } else if (strncmp(keyend, "gs", 2) == 0) { > >> + keyend = index(keyend + 1, ':'); > >> + keyend++; > >> + rc = wbcStringToSid(keyend, &sid); > >> + if (rc) > >> + syslog(LOG_DEBUG, "O strtosid: %s, rc: %d", keyend, > >> rc); > >> + else { > >> + rc = wbcSidToGid(&sid, &gid); > >> + if (rc) > >> + syslog(LOG_DEBUG, "SID %s to gid wbc error: > >> %d", > >> + keyend, rc); > >> + } > >> + if (rc) { /* either of the two wbcSid functions failed */ > >> + gr = getgrnam("nogroup"); > >> + if (!gr) > >> + syslog(LOG_DEBUG, "SID %s to gid pw error: > >> %d", > >> + keyend, rc); > >> + else { > >> + gid = gr->gr_gid; > >> + rc = 0; > >> + } > >> + } > >> + if (!rc) { /* SID has been mapped to a gid */ > >> + rc = keyctl_instantiate(key, &gid, sizeof(gid_t), 0); > >> + if (rc) > >> + syslog(LOG_ERR, "%s: key inst: %s", > >> + __func__, strerror(errno)); > >> + } > >> + } else > >> + syslog(LOG_DEBUG, "Invalid SID: %s", keyend); > >> + > >> + return rc; > >> +} > >> +#endif /* HAVE_LIBWBCLIENT */ > >> + > >> +int main(const int argc, char *const argv[]) > >> +{ > >> + int c; > >> + long rc = 1; > >> + key_serial_t key = 0; > >> + char *buf; > >> + > >> + openlog(prog, 0, LOG_DAEMON); > >> + > >> + while ((c = getopt_long(argc, argv, "v", NULL, NULL)) != -1) { > >> + switch (c) { > >> + case 'v': > >> + printf("version: %s\n", VERSION); > >> + goto out; > >> + default: > >> + syslog(LOG_ERR, "unknown option: %c", c); > >> + goto out; > >> + } > >> + } > >> + > >> + /* is there a key? */ > >> + if (argc <= optind) { > >> + usage(); > >> + goto out; > >> + } > >> + > >> + /* get key and keyring values */ > >> + errno = 0; > >> + key = strtol(argv[optind], NULL, 10); > >> + if (errno != 0) { > >> + key = 0; > >> + syslog(LOG_ERR, "Invalid key format: %s", strerror(errno)); > >> + goto out; > >> + } > >> + > >> + rc = keyctl_describe_alloc(key, &buf); > >> + if (rc == -1) { > >> + syslog(LOG_ERR, "keyctl_describe_alloc failed: %s", > >> + strerror(errno)); > >> + rc = 1; > >> + goto out; > >> + } > >> + > >> + syslog(LOG_DEBUG, "key description: %s", buf); > >> + > >> +#ifdef HAVE_LIBWBCLIENT > >> + if ((strncmp(buf, "cifs.idmap", sizeof("cifs.idmap") - 1) == 0)) > >> + rc = cifs_idmap(key, buf); > >> +#endif /* HAVE_LIBWBCLIENT */ > >> + > > > > Doesn't this program require libwbclient? If so, then why the #ifdef's? > > > >> +out: > >> + /* > >> + * on error, negatively instantiate the key ourselves so that we can > >> + * make sure the kernel doesn't hang it off of a searchable keyring > >> + * and interfere with the next attempt to instantiate the key. > >> + */ > >> + if (rc != 0 && key == 0) > >> + keyctl_negate(key, 1, KEY_REQKEY_DEFL_DEFAULT); > > > > ^^^^^^^ > > Is a 1s timeout appropriate here? > > Not sure about the value? Would 30s or 60s timeout be appropriate? > Once a key request was fulfilled successfully, cifs module is not likely > to re-request that at key since it caches for an hour or so. > And if key request was unsuccessful, cifs module will not re-request > that key for another five minutes. > > Perhaps we can negatively instantiate it for 60 seconds and be ready > to handle any requests after that? > I think any value such as 1, 30, 60 seconds would work? > If that's the case, then there's probably no reason to negatively instantiate it at all. The kernel will do that on its own with a 60s timeout (I think). > > > >> + return rc; > >> +} > >> diff --git a/configure.ac b/configure.ac > >> index e0e2a60..d9eaead 100644 > >> --- a/configure.ac > >> +++ b/configure.ac > >> @@ -22,13 +22,19 @@ AC_ARG_ENABLE(cifscreds, > >> enable_cifscreds=$enableval, > >> enable_cifscreds="no") > >> > >> +AC_ARG_ENABLE(cifsidmap, > >> + [AC_HELP_STRING([--enable-cifsidmap], > >> + [Create cifs.idmap binary @<:@default=yes@:>@])], > >> + enable_cifsidmap=$enableval, > >> + enable_cifsidmap="maybe") > >> + > >> # Checks for programs. > >> AC_PROG_CC > >> AC_PROG_SED > >> AC_GNU_SOURCE > >> > >> # Checks for header files. > >> -AC_CHECK_HEADERS([arpa/inet.h ctype.h fcntl.h inttypes.h limits.h > >> mntent.h netdb.h stddef.h stdint.h stdlib.h string.h strings.h sys/mount.h > >> sys/param.h sys/socket.h sys/time.h syslog.h unistd.h], , > >> [AC_MSG_ERROR([necessary header(s) not found])]) > >> +AC_CHECK_HEADERS([arpa/inet.h ctype.h fcntl.h inttypes.h limits.h > >> mntent.h netdb.h stddef.h stdint.h stdbool.h stdlib.h stdio.h errno.h > >> string.h strings.h sys/mount.h sys/param.h sys/socket.h sys/time.h > >> syslog.h unistd.h], , [AC_MSG_ERROR([necessary header(s) not found])]) > >> > >> if test $enable_cifsupcall != "no"; then > >> AC_CHECK_HEADERS([krb5.h krb5/krb5.h]) > >> @@ -89,6 +95,55 @@ if test $enable_cifsupcall != "no"; then > >> AC_SUBST(KRB5_LDADD) > >> fi > >> > >> +if test $enable_cifsidmap != "no"; then > >> + AC_CHECK_HEADERS([keyutils.h], , [ > >> + if test "$enable_cifsidmap" = "yes"; then > >> + AC_MSG_ERROR([keyutils.h not found, > >> consider installing keyutils-libs-devel.]) > >> + else > >> + AC_MSG_WARN([keyutils.h not found, > >> consider installing keyutils-libs-devel. Disabling cifs.idmap.]) > >> + enable_cifsidmap="no" > >> + fi > >> + ]) > >> +fi > >> + > > > > We're already doing a AC_CHECK_HEADERS for keyutils.h -- I don't think > > we want to do it again. Just use the same check for both cifs.upcall > > and cifs.idmap. > > > >> +if test $enable_cifsidmap != "no"; then > >> + AC_CHECK_HEADERS([wbclient.h], , [ > >> + if test "$enable_cifsidmap" = "yes"; then > >> + AC_MSG_ERROR([wbclient.h not found, > >> consider installing libwbclient-devel..]) > >> + else > >> + AC_MSG_WARN([keyutils.h not found, > >> consider installing libwbclient-devel. Disabling cifs.idmap.]) > >> + enable_cifsidmap="no" > >> + fi > >> + ], > >> +[#ifdef HAVE_STDINT_H > >> +#include <stdint.h> > >> +#endif > >> +] > >> +[#ifdef HAVE_STDBOOL_H > >> +#include <stdbool.h> > >> +#endif > >> +] > >> +[#ifdef HAVE_STDIO_H > >> +#include <stdio.h> > >> +#endif > >> +] > >> +[#ifdef HAVE_STDLIB_H > >> +#include <stdlib.h> > >> +#endif > >> +] > >> +[#ifdef HAVE_ERRNO_H > >> +#include <errno.h> > >> +#endif > >> +] > >> +) > >> +fi > >> + > >> +if test $enable_cifsidmap != "no"; then > >> + AC_CHECK_LIB([wbclient], [wbcStringToSid], > >> + [ WINB_LDADD='-lwbclient' ] [ AC_DEFINE(HAVE_LIBWBCLIENT, 1, > >> ["define var have_libwbclient"]) ], [AC_MSG_ERROR([no functioning wbclient > >> library found!])]) > >> + AC_SUBST(WINB_LDADD) > >> +fi > >> + > > > > > > Bleh, that's pretty messy. Maybe this should go into a separate > > file/function in aclocal/ ? > > > > > >> if test $enable_cifscreds = "yes"; then > >> AC_CHECK_HEADERS([keyutils.h], , [AC_MSG_ERROR([keyutils.h not > >> found, consider installing keyutils-libs-devel.])]) > >> fi > >> @@ -140,6 +195,7 @@ LIBS=$cu_saved_libs > >> > >> AM_CONDITIONAL(CONFIG_CIFSUPCALL, [test "$enable_cifsupcall" != "no"]) > >> AM_CONDITIONAL(CONFIG_CIFSCREDS, [test "$enable_cifscreds" = "yes"]) > >> +AM_CONDITIONAL(CONFIG_CIFSIDMAP, [test "$enable_cifsidmap" != "no"]) > >> > >> LIBCAP_NG_PATH > >> > > > > > > -- > > Jeff Layton <[email protected]> > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-cifs" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Jeff Layton <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
