From 1b327bbfa9728e3e2f9ec02371b94069c9664f2f Mon Sep 17 00:00:00 2001 From: Manoj Srivastava Date: Sun, 9 Feb 2014 16:09:49 +0000 Subject: Handle SELinux authorisation roles Rejected upstream due to discomfort with magic usernames; a better approach will need an SSH protocol change. In the meantime, this came from Debian's SELinux maintainer, so we'll keep it until we have something better. Bug: https://bugzilla.mindrot.org/show_bug.cgi?id=1641 Bug-Debian: http://bugs.debian.org/394795 Last-Update: 2024-07-03 Patch-Name: selinux-role.patch --- auth.h | 1 + auth2.c | 10 ++++++++-- monitor.c | 36 +++++++++++++++++++++++++++++++++--- monitor.h | 2 ++ monitor_wrap.c | 27 ++++++++++++++++++++++++--- monitor_wrap.h | 3 ++- openbsd-compat/port-linux.c | 21 ++++++++++++++------- openbsd-compat/port-linux.h | 4 ++-- platform.c | 4 ++-- platform.h | 2 +- session.c | 8 ++++---- session.h | 2 +- sshd-session.c | 2 +- sshpty.c | 4 ++-- sshpty.h | 2 +- 15 files changed, 98 insertions(+), 30 deletions(-) diff --git a/auth.h b/auth.h index 98bb23d4c..59799a812 100644 --- a/auth.h +++ b/auth.h @@ -65,6 +65,7 @@ struct Authctxt { char *service; struct passwd *pw; /* set if 'valid' */ char *style; + char *role; /* Method lists for multiple authentication */ char **auth_methods; /* modified from server config */ diff --git a/auth2.c b/auth2.c index f75f1d20d..44558851e 100644 --- a/auth2.c +++ b/auth2.c @@ -272,7 +272,7 @@ input_userauth_request(int type, u_int32_t seq, struct ssh *ssh) { Authctxt *authctxt = ssh->authctxt; Authmethod *m = NULL; - char *user = NULL, *service = NULL, *method = NULL, *style = NULL; + char *user = NULL, *service = NULL, *method = NULL, *style = NULL, *role = NULL; int r, authenticated = 0; double tstart = monotime_double(); @@ -286,8 +286,13 @@ input_userauth_request(int type, u_int32_t seq, struct ssh *ssh) debug("userauth-request for user %s service %s method %s", user, service, method); debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); + if ((role = strchr(user, '/')) != NULL) + *role++ = 0; + if ((style = strchr(user, ':')) != NULL) *style++ = 0; + else if (role && (style = strchr(role, ':')) != NULL) + *style++ = '\0'; if (authctxt->attempt >= 1024) auth_maxtries_exceeded(ssh); @@ -315,7 +320,8 @@ input_userauth_request(int type, u_int32_t seq, struct ssh *ssh) setproctitle("%s [net]", authctxt->valid ? user : "unknown"); authctxt->service = xstrdup(service); authctxt->style = style ? xstrdup(style) : NULL; - mm_inform_authserv(service, style); + authctxt->role = role ? xstrdup(role) : NULL; + mm_inform_authserv(service, style, role); userauth_banner(ssh); if ((r = kex_server_update_ext_info(ssh)) != 0) fatal_fr(r, "kex_server_update_ext_info failed"); diff --git a/monitor.c b/monitor.c index 92e2ca107..62cc2da6b 100644 --- a/monitor.c +++ b/monitor.c @@ -117,6 +117,7 @@ int mm_answer_sign(struct ssh *, int, struct sshbuf *); int mm_answer_pwnamallow(struct ssh *, int, struct sshbuf *); int mm_answer_auth2_read_banner(struct ssh *, int, struct sshbuf *); int mm_answer_authserv(struct ssh *, int, struct sshbuf *); +int mm_answer_authrole(struct ssh *, int, struct sshbuf *); int mm_answer_authpassword(struct ssh *, int, struct sshbuf *); int mm_answer_bsdauthquery(struct ssh *, int, struct sshbuf *); int mm_answer_bsdauthrespond(struct ssh *, int, struct sshbuf *); @@ -191,6 +192,7 @@ struct mon_table mon_dispatch_proto20[] = { {MONITOR_REQ_SIGN, MON_ONCE, mm_answer_sign}, {MONITOR_REQ_PWNAM, MON_ONCE, mm_answer_pwnamallow}, {MONITOR_REQ_AUTHSERV, MON_ONCE, mm_answer_authserv}, + {MONITOR_REQ_AUTHROLE, MON_ONCE, mm_answer_authrole}, {MONITOR_REQ_AUTH2_READ_BANNER, MON_ONCE, mm_answer_auth2_read_banner}, {MONITOR_REQ_AUTHPASSWORD, MON_AUTH, mm_answer_authpassword}, #ifdef USE_PAM @@ -832,6 +834,7 @@ mm_answer_pwnamallow(struct ssh *ssh, int sock, struct sshbuf *m) /* Allow service/style information on the auth context */ monitor_permit(mon_dispatch, MONITOR_REQ_AUTHSERV, 1); + monitor_permit(mon_dispatch, MONITOR_REQ_AUTHROLE, 1); monitor_permit(mon_dispatch, MONITOR_REQ_AUTH2_READ_BANNER, 1); #ifdef USE_PAM @@ -865,15 +868,42 @@ mm_answer_authserv(struct ssh *ssh, int sock, struct sshbuf *m) monitor_permit_authentications(1); if ((r = sshbuf_get_cstring(m, &authctxt->service, NULL)) != 0 || - (r = sshbuf_get_cstring(m, &authctxt->style, NULL)) != 0) + (r = sshbuf_get_cstring(m, &authctxt->style, NULL)) != 0 || + (r = sshbuf_get_cstring(m, &authctxt->role, NULL)) != 0) fatal_fr(r, "parse"); - debug3_f("service=%s, style=%s", authctxt->service, authctxt->style); + debug3_f("service=%s, style=%s, role=%s", + authctxt->service, authctxt->style, authctxt->role); if (strlen(authctxt->style) == 0) { free(authctxt->style); authctxt->style = NULL; } + if (strlen(authctxt->role) == 0) { + free(authctxt->role); + authctxt->role = NULL; + } + + return (0); +} + +int +mm_answer_authrole(struct ssh *ssh, int sock, struct sshbuf *m) +{ + int r; + + monitor_permit_authentications(1); + + if ((r = sshbuf_get_cstring(m, &authctxt->role, NULL)) != 0) + fatal("%s: buffer error: %s", __func__, ssh_err(r)); + debug3("%s: role=%s", + __func__, authctxt->role); + + if (strlen(authctxt->role) == 0) { + free(authctxt->role); + authctxt->role = NULL; + } + return (0); } @@ -1594,7 +1624,7 @@ mm_answer_pty(struct ssh *ssh, int sock, struct sshbuf *m) res = pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty)); if (res == 0) goto error; - pty_setowner(authctxt->pw, s->tty); + pty_setowner(authctxt->pw, s->tty, authctxt->role); if ((r = sshbuf_put_u32(m, 1)) != 0 || (r = sshbuf_put_cstring(m, s->tty)) != 0) diff --git a/monitor.h b/monitor.h index 7d8f3c6fa..d84415fe2 100644 --- a/monitor.h +++ b/monitor.h @@ -65,6 +65,8 @@ enum monitor_reqtype { MONITOR_REQ_GSSSIGN = 150, MONITOR_ANS_GSSSIGN = 151, MONITOR_REQ_GSSUPCREDS = 152, MONITOR_ANS_GSSUPCREDS = 153, + + MONITOR_REQ_AUTHROLE = 154, }; struct ssh; diff --git a/monitor_wrap.c b/monitor_wrap.c index cb3261b4d..60c339d02 100644 --- a/monitor_wrap.c +++ b/monitor_wrap.c @@ -431,10 +431,10 @@ mm_auth2_read_banner(void) return (banner); } -/* Inform the privileged process about service and style */ +/* Inform the privileged process about service, style, and role */ void -mm_inform_authserv(char *service, char *style) +mm_inform_authserv(char *service, char *style, char *role) { struct sshbuf *m; int r; @@ -444,7 +444,8 @@ mm_inform_authserv(char *service, char *style) if ((m = sshbuf_new()) == NULL) fatal_f("sshbuf_new failed"); if ((r = sshbuf_put_cstring(m, service)) != 0 || - (r = sshbuf_put_cstring(m, style ? style : "")) != 0) + (r = sshbuf_put_cstring(m, style ? style : "")) != 0 || + (r = sshbuf_put_cstring(m, role ? role : "")) != 0) fatal_fr(r, "assemble"); mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_AUTHSERV, m); @@ -452,6 +453,26 @@ mm_inform_authserv(char *service, char *style) sshbuf_free(m); } +/* Inform the privileged process about role */ + +void +mm_inform_authrole(char *role) +{ + struct sshbuf *m; + int r; + + debug3("%s entering", __func__); + + if ((m = sshbuf_new()) == NULL) + fatal("%s: sshbuf_new failed", __func__); + if ((r = sshbuf_put_cstring(m, role ? role : "")) != 0) + fatal("%s: buffer error: %s", __func__, ssh_err(r)); + + mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_AUTHROLE, m); + + sshbuf_free(m); +} + /* Do the password authentication */ int mm_auth_password(struct ssh *ssh, char *password) diff --git a/monitor_wrap.h b/monitor_wrap.h index 09b0ccaaa..2493da591 100644 --- a/monitor_wrap.h +++ b/monitor_wrap.h @@ -45,7 +45,8 @@ DH *mm_choose_dh(int, int, int); int mm_sshkey_sign(struct ssh *, struct sshkey *, u_char **, size_t *, const u_char *, size_t, const char *, const char *, const char *, u_int compat); -void mm_inform_authserv(char *, char *); +void mm_inform_authserv(char *, char *, char *); +void mm_inform_authrole(char *); struct passwd *mm_getpwnamallow(struct ssh *, const char *); char *mm_auth2_read_banner(void); int mm_auth_password(struct ssh *, char *); diff --git a/openbsd-compat/port-linux.c b/openbsd-compat/port-linux.c index 4c024c6d2..4fe61f020 100644 --- a/openbsd-compat/port-linux.c +++ b/openbsd-compat/port-linux.c @@ -65,7 +65,7 @@ ssh_selinux_enabled(void) /* Return the default security context for the given username */ static char * -ssh_selinux_getctxbyname(char *pwname) +ssh_selinux_getctxbyname(char *pwname, const char *role) { char *sc = NULL, *sename = NULL, *lvl = NULL; int r; @@ -79,9 +79,16 @@ ssh_selinux_getctxbyname(char *pwname) #endif #ifdef HAVE_GET_DEFAULT_CONTEXT_WITH_LEVEL - r = get_default_context_with_level(sename, lvl, NULL, &sc); + if (role != NULL && role[0]) + r = get_default_context_with_rolelevel(sename, role, lvl, NULL, + &sc); + else + r = get_default_context_with_level(sename, lvl, NULL, &sc); #else - r = get_default_context(sename, NULL, &sc); + if (role != NULL && role[0]) + r = get_default_context_with_role(sename, role, NULL, &sc); + else + r = get_default_context(sename, NULL, &sc); #endif if (r != 0) { @@ -111,7 +118,7 @@ ssh_selinux_getctxbyname(char *pwname) /* Set the execution context to the default for the specified user */ void -ssh_selinux_setup_exec_context(char *pwname) +ssh_selinux_setup_exec_context(char *pwname, const char *role) { char *user_ctx = NULL; @@ -120,7 +127,7 @@ ssh_selinux_setup_exec_context(char *pwname) debug3("%s: setting execution context", __func__); - user_ctx = ssh_selinux_getctxbyname(pwname); + user_ctx = ssh_selinux_getctxbyname(pwname, role); if (setexeccon(user_ctx) != 0) { switch (security_getenforce()) { case -1: @@ -142,7 +149,7 @@ ssh_selinux_setup_exec_context(char *pwname) /* Set the TTY context for the specified user */ void -ssh_selinux_setup_pty(char *pwname, const char *tty) +ssh_selinux_setup_pty(char *pwname, const char *tty, const char *role) { char *new_tty_ctx = NULL, *user_ctx = NULL, *old_tty_ctx = NULL; security_class_t chrclass; @@ -152,7 +159,7 @@ ssh_selinux_setup_pty(char *pwname, const char *tty) debug3("%s: setting TTY context on %s", __func__, tty); - user_ctx = ssh_selinux_getctxbyname(pwname); + user_ctx = ssh_selinux_getctxbyname(pwname, role); /* XXX: should these calls fatal() upon failure in enforcing mode? */ diff --git a/openbsd-compat/port-linux.h b/openbsd-compat/port-linux.h index 14064f87d..6c4c37115 100644 --- a/openbsd-compat/port-linux.h +++ b/openbsd-compat/port-linux.h @@ -19,8 +19,8 @@ #ifdef WITH_SELINUX int ssh_selinux_enabled(void); -void ssh_selinux_setup_pty(char *, const char *); -void ssh_selinux_setup_exec_context(char *); +void ssh_selinux_setup_pty(char *, const char *, const char *); +void ssh_selinux_setup_exec_context(char *, const char *); void ssh_selinux_change_context(const char *); void ssh_selinux_setfscreatecon(const char *); #endif diff --git a/platform.c b/platform.c index 4c4fe57ea..f3dc7c3a8 100644 --- a/platform.c +++ b/platform.c @@ -99,7 +99,7 @@ platform_setusercontext(struct passwd *pw) * called if sshd is running as root. */ void -platform_setusercontext_post_groups(struct passwd *pw) +platform_setusercontext_post_groups(struct passwd *pw, const char *role) { #if !defined(HAVE_LOGIN_CAP) && defined(USE_PAM) /* @@ -140,7 +140,7 @@ platform_setusercontext_post_groups(struct passwd *pw) } #endif /* HAVE_SETPCRED */ #ifdef WITH_SELINUX - ssh_selinux_setup_exec_context(pw->pw_name); + ssh_selinux_setup_exec_context(pw->pw_name, role); #endif } diff --git a/platform.h b/platform.h index 5dec23276..1b77c3e3d 100644 --- a/platform.h +++ b/platform.h @@ -26,7 +26,7 @@ void platform_post_fork_parent(pid_t child_pid); void platform_post_fork_child(void); int platform_privileged_uidswap(void); void platform_setusercontext(struct passwd *); -void platform_setusercontext_post_groups(struct passwd *); +void platform_setusercontext_post_groups(struct passwd *, const char *); char *platform_get_krb5_client(const char *); char *platform_krb5_get_principal_name(const char *); int platform_locked_account(struct passwd *); diff --git a/session.c b/session.c index 3d9a16b1e..1c67f9fd1 100644 --- a/session.c +++ b/session.c @@ -1344,7 +1344,7 @@ safely_chroot(const char *path, uid_t uid) /* Set login name, uid, gid, and groups. */ void -do_setusercontext(struct passwd *pw) +do_setusercontext(struct passwd *pw, const char *role) { char uidstr[32], *chroot_path, *tmp; @@ -1372,7 +1372,7 @@ do_setusercontext(struct passwd *pw) endgrent(); #endif - platform_setusercontext_post_groups(pw); + platform_setusercontext_post_groups(pw, role); if (!in_chroot && options.chroot_directory != NULL && strcasecmp(options.chroot_directory, "none") != 0) { @@ -1516,7 +1516,7 @@ do_child(struct ssh *ssh, Session *s, const char *command) /* Force a password change */ if (s->authctxt->force_pwchange) { - do_setusercontext(pw); + do_setusercontext(pw, s->authctxt->role); child_close_fds(ssh); do_pwchange(s); exit(1); @@ -1534,7 +1534,7 @@ do_child(struct ssh *ssh, Session *s, const char *command) /* When PAM is enabled we rely on it to do the nologin check */ if (!options.use_pam) do_nologin(pw); - do_setusercontext(pw); + do_setusercontext(pw, s->authctxt->role); /* * PAM session modules in do_setusercontext may have * generated messages, so if this in an interactive diff --git a/session.h b/session.h index 344a1ddf9..20ea822a7 100644 --- a/session.h +++ b/session.h @@ -77,7 +77,7 @@ void session_pty_cleanup2(Session *); Session *session_new(void); Session *session_by_tty(char *); void session_close(struct ssh *, Session *); -void do_setusercontext(struct passwd *); +void do_setusercontext(struct passwd *, const char *); const char *session_get_remote_name_or_ip(struct ssh *, u_int, int); diff --git a/sshd-session.c b/sshd-session.c index a9fa63224..f0fd85367 100644 --- a/sshd-session.c +++ b/sshd-session.c @@ -438,7 +438,7 @@ privsep_postauth(struct ssh *ssh, Authctxt *authctxt) /* Drop privileges */ if (!skip_privdrop) - do_setusercontext(authctxt->pw); + do_setusercontext(authctxt->pw, authctxt->role); /* It is safe now to apply the key state */ monitor_apply_keystate(ssh, pmonitor); diff --git a/sshpty.c b/sshpty.c index cae0b977a..7870c6482 100644 --- a/sshpty.c +++ b/sshpty.c @@ -163,7 +163,7 @@ pty_change_window_size(int ptyfd, u_int row, u_int col, } void -pty_setowner(struct passwd *pw, const char *tty) +pty_setowner(struct passwd *pw, const char *tty, const char *role) { struct group *grp; gid_t gid; @@ -187,7 +187,7 @@ pty_setowner(struct passwd *pw, const char *tty) strerror(errno)); #ifdef WITH_SELINUX - ssh_selinux_setup_pty(pw->pw_name, tty); + ssh_selinux_setup_pty(pw->pw_name, tty, role); #endif if (st.st_uid != pw->pw_uid || st.st_gid != gid) { diff --git a/sshpty.h b/sshpty.h index 9ec7e9a15..de7e000ae 100644 --- a/sshpty.h +++ b/sshpty.h @@ -24,5 +24,5 @@ int pty_allocate(int *, int *, char *, size_t); void pty_release(const char *); void pty_make_controlling_tty(int *, const char *); void pty_change_window_size(int, u_int, u_int, u_int, u_int); -void pty_setowner(struct passwd *, const char *); +void pty_setowner(struct passwd *, const char *, const char *); void disconnect_controlling_tty(void);