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openssh/openssh-4.5p1-mls.patch
Tomáš Mráz c3274ccb32 - experimental NSS keys support 
- correctly setup context when empty level requested (#234951)
2007-06-20 17:47:18 +00:00

424 lines
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--- openssh-4.5p1/openbsd-compat/port-linux.c.mls 2007-01-16 22:13:32.000000000 +0100
+++ openssh-4.5p1/openbsd-compat/port-linux.c 2007-03-20 10:07:39.000000000 +0100
@@ -33,12 +33,23 @@
#include "key.h"
#include "hostfile.h"
#include "auth.h"
+#include "xmalloc.h"
#include <selinux/selinux.h>
#include <selinux/flask.h>
+#include <selinux/context.h>
#include <selinux/get_context_list.h>
+#include <selinux/get_default_type.h>
+#include <selinux/av_permissions.h>
+
+#ifdef HAVE_LINUX_AUDIT
+#include <libaudit.h>
+#include <unistd.h>
+#endif
extern Authctxt *the_authctxt;
+extern int inetd_flag;
+extern int rexeced_flag;
/* Wrapper around is_selinux_enabled() to log its return value once only */
static int
@@ -54,17 +65,173 @@
return (enabled);
}
+/* Send audit message */
+static int
+send_audit_message(int success, security_context_t default_context,
+ security_context_t selected_context)
+{
+ int rc=0;
+#ifdef HAVE_LINUX_AUDIT
+ char *msg = NULL;
+ int audit_fd = audit_open();
+ security_context_t default_raw=NULL;
+ security_context_t selected_raw=NULL;
+ rc = -1;
+ if (audit_fd < 0) {
+ if (errno == EINVAL || errno == EPROTONOSUPPORT ||
+ errno == EAFNOSUPPORT)
+ return 0; /* No audit support in kernel */
+ error("Error connecting to audit system.");
+ return rc;
+ }
+ if (selinux_trans_to_raw_context(default_context, &default_raw) < 0) {
+ error("Error translating default context.");
+ default_raw = NULL;
+ }
+ if (selinux_trans_to_raw_context(selected_context, &selected_raw) < 0) {
+ error("Error translating selected context.");
+ selected_raw = NULL;
+ }
+ if (asprintf(&msg, "sshd: default-context=%s selected-context=%s",
+ default_raw ? default_raw : (default_context ? default_context: "?"),
+ selected_context ? selected_raw : (selected_context ? selected_context :"?")) < 0) {
+ error("Error allocating memory.");
+ goto out;
+ }
+ if (audit_log_user_message(audit_fd, AUDIT_USER_ROLE_CHANGE,
+ msg, NULL, NULL, NULL, success) <= 0) {
+ error("Error sending audit message.");
+ goto out;
+ }
+ rc = 0;
+ out:
+ free(msg);
+ freecon(default_raw);
+ freecon(selected_raw);
+ close(audit_fd);
+#endif
+ return rc;
+}
+
+static int
+mls_range_allowed(security_context_t src, security_context_t dst)
+{
+ struct av_decision avd;
+ int retval;
+ unsigned int bit = CONTEXT__CONTAINS;
+
+ debug("%s: src:%s dst:%s", __func__, src, dst);
+ retval = security_compute_av(src, dst, SECCLASS_CONTEXT, bit, &avd);
+ if (retval || ((bit & avd.allowed) != bit))
+ return 0;
+
+ return 1;
+}
+
+static int
+get_user_context(const char *sename, const char *role, const char *lvl,
+ security_context_t *sc) {
+#ifdef HAVE_GET_DEFAULT_CONTEXT_WITH_LEVEL
+ if (lvl == NULL || lvl[0] == '\0' || get_default_context_with_level(sename, lvl, NULL, sc) != 0) {
+ /* User may have requested a level completely outside of his
+ allowed range. We get a context just for auditing as the
+ range check below will certainly fail for default context. */
+#endif
+ if (get_default_context(sename, NULL, sc) != 0) {
+ *sc = NULL;
+ return -1;
+ }
+#ifdef HAVE_GET_DEFAULT_CONTEXT_WITH_LEVEL
+ }
+#endif
+ if (role != NULL && role[0]) {
+ context_t con;
+ char *type=NULL;
+ if (get_default_type(role, &type) != 0) {
+ error("get_default_type: failed to get default type for '%s'",
+ role);
+ goto out;
+ }
+ con = context_new(*sc);
+ if (!con) {
+ goto out;
+ }
+ context_role_set(con, role);
+ context_type_set(con, type);
+ freecon(*sc);
+ *sc = strdup(context_str(con));
+ context_free(con);
+ if (!*sc)
+ return -1;
+ }
+#ifdef HAVE_GET_DEFAULT_CONTEXT_WITH_LEVEL
+ if (lvl != NULL && lvl[0]) {
+ /* verify that the requested range is obtained */
+ context_t con;
+ security_context_t obtained_raw;
+ security_context_t requested_raw;
+ con = context_new(*sc);
+ if (!con) {
+ goto out;
+ }
+ context_range_set(con, lvl);
+ if (selinux_trans_to_raw_context(*sc, &obtained_raw) < 0) {
+ context_free(con);
+ goto out;
+ }
+ if (selinux_trans_to_raw_context(context_str(con), &requested_raw) < 0) {
+ freecon(obtained_raw);
+ context_free(con);
+ goto out;
+ }
+
+ debug("get_user_context: obtained context '%s' requested context '%s'",
+ obtained_raw, requested_raw);
+ if (strcmp(obtained_raw, requested_raw)) {
+ /* set the context to the real requested one but fail */
+ freecon(requested_raw);
+ freecon(obtained_raw);
+ freecon(*sc);
+ *sc = strdup(context_str(con));
+ context_free(con);
+ return -1;
+ }
+ freecon(requested_raw);
+ freecon(obtained_raw);
+ context_free(con);
+ }
+#endif
+ return 0;
+ out:
+ freecon(*sc);
+ *sc = NULL;
+ return -1;
+}
+
/* Return the default security context for the given username */
-static security_context_t
-ssh_selinux_getctxbyname(char *pwname)
+static int
+ssh_selinux_getctxbyname(char *pwname,
+ security_context_t *default_sc, security_context_t *user_sc)
{
- security_context_t sc = NULL;
char *sename, *lvl;
+ const char *reqlvl = NULL;
char *role = NULL;
- int r = 0;
+ int r = -1;
+ context_t con = NULL;
+
+ *default_sc = NULL;
+ *user_sc = NULL;
+ if (the_authctxt) {
+ if (the_authctxt->role != NULL) {
+ char *slash;
+ role = xstrdup(the_authctxt->role);
+ if ((slash = strchr(role, '/')) != NULL) {
+ *slash = '\0';
+ reqlvl = slash + 1;
+ }
+ }
+ }
- if (the_authctxt)
- role=the_authctxt->role;
#ifdef HAVE_GETSEUSERBYNAME
if ((r=getseuserbyname(pwname, &sename, &lvl)) != 0) {
sename = NULL;
@@ -72,37 +239,63 @@
}
#else
sename = pwname;
- lvl = NULL;
+ lvl = "";
#endif
if (r == 0) {
#ifdef HAVE_GET_DEFAULT_CONTEXT_WITH_LEVEL
- 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);
+ r = get_default_context_with_level(sename, lvl, NULL, default_sc);
#else
- if (role != NULL && role[0])
- r = get_default_context_with_role(sename, role, NULL, &sc);
- else
- r = get_default_context(sename, NULL, &sc);
+ r = get_default_context(sename, NULL, default_sc);
#endif
}
- if (r != 0) {
- switch (security_getenforce()) {
- case -1:
- fatal("%s: ssh_selinux_getctxbyname: "
- "security_getenforce() failed", __func__);
- case 0:
- error("%s: Failed to get default SELinux security "
- "context for %s", __func__, pwname);
- default:
- fatal("%s: Failed to get default SELinux security "
- "context for %s (in enforcing mode)",
- __func__, pwname);
+ if (r == 0) {
+ /* If launched from xinetd, we must use current level */
+ if (inetd_flag && !rexeced_flag) {
+ security_context_t sshdsc=NULL;
+
+ if (getcon_raw(&sshdsc) < 0)
+ fatal("failed to allocate security context");
+
+ if ((con=context_new(sshdsc)) == NULL)
+ fatal("failed to allocate selinux context");
+ reqlvl = context_range_get(con);
+ freecon(sshdsc);
+ if (reqlvl !=NULL && lvl != NULL && strcmp(reqlvl, lvl) == 0)
+ /* we actually don't change level */
+ reqlvl = "";
+
+ debug("%s: current connection level '%s'", __func__, reqlvl);
+ }
+
+ if ((reqlvl != NULL && reqlvl[0]) || (role != NULL && role[0])) {
+ r = get_user_context(sename, role, reqlvl, user_sc);
+
+ if (r == 0 && reqlvl != NULL && reqlvl[0]) {
+ security_context_t default_level_sc = *default_sc;
+ if (role != NULL && role[0]) {
+ if (get_user_context(sename, role, lvl, &default_level_sc) < 0)
+ default_level_sc = *default_sc;
+ }
+ /* verify that the requested range is contained in the user range */
+ if (mls_range_allowed(default_level_sc, *user_sc)) {
+ logit("permit MLS level %s (user range %s)", reqlvl, lvl);
+ } else {
+ r = -1;
+ error("deny MLS level %s (user range %s)", reqlvl, lvl);
+ }
+ if (default_level_sc != *default_sc)
+ freecon(default_level_sc);
+ }
+ } else {
+ *user_sc = *default_sc;
}
}
+ if (r != 0) {
+ error("%s: Failed to get default SELinux security "
+ "context for %s", __func__, pwname);
+ }
#ifdef HAVE_GETSEUSERBYNAME
if (sename != NULL)
@@ -110,14 +303,20 @@
if (lvl != NULL)
xfree(lvl);
#endif
+ if (role != NULL)
+ xfree(role);
+ if (con)
+ context_free(con);
- return (sc);
+ return (r);
}
/* Set the execution context to the default for the specified user */
void
ssh_selinux_setup_exec_context(char *pwname)
{
+ int r = 0;
+ security_context_t default_ctx = NULL;
security_context_t user_ctx = NULL;
if (!ssh_selinux_enabled())
@@ -125,21 +324,39 @@
debug3("%s: setting execution context", __func__);
- user_ctx = ssh_selinux_getctxbyname(pwname);
- if (setexeccon(user_ctx) != 0) {
+ r = ssh_selinux_getctxbyname(pwname, &default_ctx, &user_ctx);
+ if (r >= 0) {
+ r = setexeccon(user_ctx);
+ if (r < 0) {
+ error("%s: Failed to set SELinux execution context %s for %s",
+ __func__, user_ctx, pwname);
+ }
+ }
+ if (user_ctx == NULL) {
+ user_ctx = default_ctx;
+ }
+ if (r < 0 || user_ctx != default_ctx) {
+ /* audit just the case when user changed a role or there was
+ a failure */
+ send_audit_message(r >= 0, default_ctx, user_ctx);
+ }
+ if (r < 0) {
switch (security_getenforce()) {
case -1:
fatal("%s: security_getenforce() failed", __func__);
case 0:
- error("%s: Failed to set SELinux execution "
- "context for %s", __func__, pwname);
+ error("%s: SELinux failure. Continuing in permissive mode.",
+ __func__);
+ break;
default:
- fatal("%s: Failed to set SELinux execution context "
- "for %s (in enforcing mode)", __func__, pwname);
+ fatal("%s: SELinux failure. Aborting connection.",
+ __func__);
}
}
- if (user_ctx != NULL)
+ if (user_ctx != NULL && user_ctx != default_ctx)
freecon(user_ctx);
+ if (default_ctx != NULL)
+ freecon(default_ctx);
debug3("%s: done", __func__);
}
@@ -157,7 +374,10 @@
debug3("%s: setting TTY context on %s", __func__, tty);
- user_ctx = ssh_selinux_getctxbyname(pwname);
+ if (getexeccon(&user_ctx) < 0) {
+ error("%s: getexeccon: %s", __func__, strerror(errno));
+ goto out;
+ }
/* XXX: should these calls fatal() upon failure in enforcing mode? */
--- openssh-4.5p1/sshd.c.mls 2007-01-16 22:13:32.000000000 +0100
+++ openssh-4.5p1/sshd.c 2007-01-16 22:13:32.000000000 +0100
@@ -1833,6 +1833,9 @@
restore_uid();
}
#endif
+#ifdef WITH_SELINUX
+ ssh_selinux_setup_exec_context(authctxt->pw->pw_name);
+#endif
#ifdef USE_PAM
if (options.use_pam) {
do_pam_setcred(1);
--- openssh-4.5p1/misc.c.mls 2006-08-05 04:39:40.000000000 +0200
+++ openssh-4.5p1/misc.c 2007-01-16 22:13:32.000000000 +0100
@@ -418,6 +418,7 @@
colon(char *cp)
{
int flag = 0;
+ int start = 1;
if (*cp == ':') /* Leading colon is part of file name. */
return (0);
@@ -431,8 +432,13 @@
return (cp+1);
if (*cp == ':' && !flag)
return (cp);
- if (*cp == '/')
- return (0);
+ if (start) {
+ /* Slash on beginning or after dots only denotes file name. */
+ if (*cp == '/')
+ return (0);
+ if (*cp != '.')
+ start = 0;
+ }
}
return (0);
}
--- openssh-4.5p1/session.c.mls 2007-01-16 22:13:32.000000000 +0100
+++ openssh-4.5p1/session.c 2007-01-16 22:13:32.000000000 +0100
@@ -1347,10 +1347,6 @@
#endif
if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid)
fatal("Failed to set uids to %u.", (u_int) pw->pw_uid);
-
-#ifdef WITH_SELINUX
- ssh_selinux_setup_exec_context(pw->pw_name);
-#endif
}
static void
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