Adding upstream version 1.8.27.upstream/1.8.27upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 460 insertions, 0 deletions

diff --git a/src/selinux.c b/src/selinux.c
new file mode 100644
index 0000000..ed36d89
--- /dev/null
+++ b/src/selinux.c
@@ -0,0 +1,460 @@
+/*
+ * Copyright (c) 2009-2016 Todd C. Miller <Todd.Miller@sudo.ws>
+ * Copyright (c) 2008 Dan Walsh <dwalsh@redhat.com>
+ *
+ * Borrowed heavily from newrole source code
+ * Authors:
+ *	Anthony Colatrella
+ *	Tim Fraser
+ *	Steve Grubb <sgrubb@redhat.com>
+ *	Darrel Goeddel <DGoeddel@trustedcs.com>
+ *	Michael Thompson <mcthomps@us.ibm.com>
+ *	Dan Walsh <dwalsh@redhat.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * This is an open source non-commercial project. Dear PVS-Studio, please check it.
+ * PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
+ */
+
+#include <config.h>
+
+#ifdef HAVE_SELINUX
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+
+#include <selinux/selinux.h>           /* for is_selinux_enabled() */
+#include <selinux/context.h>           /* for context-mangling functions */
+#include <selinux/get_default_type.h>
+#include <selinux/get_context_list.h>
+
+#ifdef HAVE_LINUX_AUDIT
+# include <libaudit.h>
+#endif
+
+#include "sudo.h"
+#include "sudo_exec.h"
+
+static struct selinux_state {
+    security_context_t old_context;
+    security_context_t new_context;
+    security_context_t tty_context;
+    security_context_t new_tty_context;
+    const char *ttyn;
+    int ttyfd;
+    int enforcing;
+} se_state;
+
+#ifdef HAVE_LINUX_AUDIT
+static int
+audit_role_change(const security_context_t old_context,
+    const security_context_t new_context, const char *ttyn, int result)
+{
+    int au_fd, rc = -1;
+    char *message;
+    debug_decl(audit_role_change, SUDO_DEBUG_SELINUX)
+
+    au_fd = audit_open();
+    if (au_fd == -1) {
+        /* Kernel may not have audit support. */
+        if (errno != EINVAL && errno != EPROTONOSUPPORT && errno != EAFNOSUPPORT
+)
+            sudo_fatal(U_("unable to open audit system"));
+    } else {
+	/* audit role change using the same format as newrole(1) */
+	rc = asprintf(&message, "newrole: old-context=%s new-context=%s",
+	    old_context, new_context);
+	if (rc == -1)
+	    sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+	rc = audit_log_user_message(au_fd, AUDIT_USER_ROLE_CHANGE,
+	    message, NULL, NULL, ttyn, result);
+	if (rc <= 0)
+	    sudo_warn(U_("unable to send audit message"));
+	free(message);
+	close(au_fd);
+    }
+
+    debug_return_int(rc);
+}
+#endif
+
+/*
+ * This function attempts to revert the relabeling done to the tty.
+ * fd		   - referencing the opened ttyn
+ * ttyn		   - name of tty to restore
+ *
+ * Returns zero on success, non-zero otherwise
+ */
+int
+selinux_restore_tty(void)
+{
+    int retval = 0;
+    security_context_t chk_tty_context = NULL;
+    debug_decl(selinux_restore_tty, SUDO_DEBUG_SELINUX)
+
+    if (se_state.ttyfd == -1 || se_state.new_tty_context == NULL)
+	goto skip_relabel;
+
+    /* Verify that the tty still has the context set by sudo. */
+    if ((retval = fgetfilecon(se_state.ttyfd, &chk_tty_context)) < 0) {
+	sudo_warn(U_("unable to fgetfilecon %s"), se_state.ttyn);
+	goto skip_relabel;
+    }
+
+    if ((retval = strcmp(chk_tty_context, se_state.new_tty_context))) {
+	sudo_warnx(U_("%s changed labels"), se_state.ttyn);
+	goto skip_relabel;
+    }
+
+    if ((retval = fsetfilecon(se_state.ttyfd, se_state.tty_context)) < 0)
+	sudo_warn(U_("unable to restore context for %s"), se_state.ttyn);
+
+skip_relabel:
+    if (se_state.ttyfd != -1) {
+	close(se_state.ttyfd);
+	se_state.ttyfd = -1;
+    }
+    if (chk_tty_context != NULL) {
+	freecon(chk_tty_context);
+	chk_tty_context = NULL;
+    }
+    debug_return_int(retval);
+}
+
+/*
+ * This function attempts to relabel the tty. If this function fails, then
+ * the contexts are free'd and -1 is returned. On success, 0 is returned
+ * and tty_context and new_tty_context are set.
+ *
+ * This function will not fail if it can not relabel the tty when selinux is
+ * in permissive mode.
+ */
+static int
+relabel_tty(const char *ttyn, int ptyfd)
+{
+    security_context_t tty_con = NULL;
+    security_context_t new_tty_con = NULL;
+    struct stat sb;
+    int fd;
+    debug_decl(relabel_tty, SUDO_DEBUG_SELINUX)
+
+    se_state.ttyfd = ptyfd;
+
+    /* It is perfectly legal to have no tty. */
+    if (ptyfd == -1 && ttyn == NULL)
+	debug_return_int(0);
+
+    /* If sudo is not allocating a pty for the command, open current tty. */
+    if (ptyfd == -1) {
+	se_state.ttyfd = open(ttyn, O_RDWR|O_NOCTTY|O_NONBLOCK);
+	if (se_state.ttyfd == -1 || fstat(se_state.ttyfd, &sb) == -1) {
+	    sudo_warn(U_("unable to open %s, not relabeling tty"), ttyn);
+	    goto bad;
+	}
+	if (!S_ISCHR(sb.st_mode)) {
+	    sudo_warn(U_("%s is not a character device, not relabeling tty"),
+		ttyn);
+	    goto bad;
+	}
+	(void)fcntl(se_state.ttyfd, F_SETFL,
+	    fcntl(se_state.ttyfd, F_GETFL, 0) & ~O_NONBLOCK);
+    }
+
+    if (fgetfilecon(se_state.ttyfd, &tty_con) < 0) {
+	sudo_warn(U_("unable to get current tty context, not relabeling tty"));
+	goto bad;
+    }
+
+    if (tty_con) {
+	security_class_t tclass = string_to_security_class("chr_file");
+	if (tclass == 0) {
+	    sudo_warn(U_("unknown security class \"chr_file\", not relabeling tty"));
+	    goto bad;
+	}
+	if (security_compute_relabel(se_state.new_context, tty_con,
+	    tclass, &new_tty_con) < 0) {
+	    sudo_warn(U_("unable to get new tty context, not relabeling tty"));
+	    goto bad;
+	}
+    }
+
+    if (new_tty_con != NULL) {
+	if (fsetfilecon(se_state.ttyfd, new_tty_con) < 0) {
+	    sudo_warn(U_("unable to set new tty context"));
+	    goto bad;
+	}
+    }
+
+    if (ptyfd != -1) {
+	/* Reopen pty that was relabeled, std{in,out,err} are reset later. */
+	se_state.ttyfd = open(ttyn, O_RDWR|O_NOCTTY, 0);
+	if (se_state.ttyfd == -1 || fstat(se_state.ttyfd, &sb) == -1) {
+	    sudo_warn(U_("unable to open %s"), ttyn);
+	    goto bad;
+	}
+	if (!S_ISCHR(sb.st_mode)) {
+	    sudo_warn(U_("%s is not a character device, not relabeling tty"),
+		ttyn);
+	    goto bad;
+	}
+	if (dup2(se_state.ttyfd, ptyfd) == -1) {
+	    sudo_warn("dup2");
+	    goto bad;
+	}
+    } else {
+	/* Re-open tty to get new label and reset std{in,out,err} */
+	close(se_state.ttyfd);
+	se_state.ttyfd = open(ttyn, O_RDWR|O_NOCTTY|O_NONBLOCK);
+	if (se_state.ttyfd == -1 || fstat(se_state.ttyfd, &sb) == -1) {
+	    sudo_warn(U_("unable to open %s"), ttyn);
+	    goto bad;
+	}
+	if (!S_ISCHR(sb.st_mode)) {
+	    sudo_warn(U_("%s is not a character device, not relabeling tty"),
+		ttyn);
+	    goto bad;
+	}
+	(void)fcntl(se_state.ttyfd, F_SETFL,
+	    fcntl(se_state.ttyfd, F_GETFL, 0) & ~O_NONBLOCK);
+	for (fd = STDIN_FILENO; fd <= STDERR_FILENO; fd++) {
+	    if (isatty(fd) && dup2(se_state.ttyfd, fd) == -1) {
+		sudo_warn("dup2");
+		goto bad;
+	    }
+	}
+    }
+    /* Retain se_state.ttyfd so we can restore label when command finishes. */
+    (void)fcntl(se_state.ttyfd, F_SETFD, FD_CLOEXEC);
+
+    se_state.ttyn = ttyn;
+    se_state.tty_context = tty_con;
+    se_state.new_tty_context = new_tty_con;
+    debug_return_int(0);
+
+bad:
+    if (se_state.ttyfd != -1 && se_state.ttyfd != ptyfd) {
+	close(se_state.ttyfd);
+	se_state.ttyfd = -1;
+    }
+    freecon(tty_con);
+    debug_return_int(se_state.enforcing ? -1 : 0);
+}
+
+/*
+ * Returns a new security context based on the old context and the
+ * specified role and type.
+ */
+security_context_t
+get_exec_context(security_context_t old_context, const char *role, const char *type)
+{
+    security_context_t new_context = NULL;
+    context_t context = NULL;
+    char *typebuf = NULL;
+    debug_decl(get_exec_context, SUDO_DEBUG_SELINUX)
+    
+    /* We must have a role, the type is optional (we can use the default). */
+    if (!role) {
+	sudo_warnx(U_("you must specify a role for type %s"), type);
+	errno = EINVAL;
+	goto bad;
+    }
+    if (!type) {
+	if (get_default_type(role, &typebuf)) {
+	    sudo_warnx(U_("unable to get default type for role %s"), role);
+	    errno = EINVAL;
+	    goto bad;
+	}
+	type = typebuf;
+    }
+    
+    /* 
+     * Expand old_context into a context_t so that we extract and modify 
+     * its components easily. 
+     */
+    context = context_new(old_context);
+    
+    /*
+     * Replace the role and type in "context" with the role and
+     * type we will be running the command as.
+     */
+    if (context_role_set(context, role)) {
+	sudo_warn(U_("failed to set new role %s"), role);
+	goto bad;
+    }
+    if (context_type_set(context, type)) {
+	sudo_warn(U_("failed to set new type %s"), type);
+	goto bad;
+    }
+      
+    /*
+     * Convert "context" back into a string and verify it.
+     */
+    if ((new_context = strdup(context_str(context))) == NULL) {
+	sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+	goto bad;
+    }
+    if (security_check_context(new_context) < 0) {
+	sudo_warnx(U_("%s is not a valid context"), new_context);
+	errno = EINVAL;
+	goto bad;
+    }
+
+#ifdef DEBUG
+    sudo_warnx("Your new context is %s", new_context);
+#endif
+
+    context_free(context);
+    debug_return_ptr(new_context);
+
+bad:
+    free(typebuf);
+    context_free(context);
+    freecon(new_context);
+    debug_return_ptr(NULL);
+}
+
+/* 
+ * Set the exec and tty contexts in preparation for fork/exec.
+ * Must run as root, before the uid change.
+ * If ptyfd is not -1, it indicates we are running
+ * in a pty and do not need to reset std{in,out,err}.
+ * Returns 0 on success and -1 on failure.
+ */
+int
+selinux_setup(const char *role, const char *type, const char *ttyn,
+    int ptyfd)
+{
+    int ret = -1;
+    debug_decl(selinux_setup, SUDO_DEBUG_SELINUX)
+
+    /* Store the caller's SID in old_context. */
+    if (getprevcon(&se_state.old_context)) {
+	sudo_warn(U_("failed to get old_context"));
+	goto done;
+    }
+
+    se_state.enforcing = security_getenforce();
+    if (se_state.enforcing < 0) {
+	sudo_warn(U_("unable to determine enforcing mode."));
+	goto done;
+    }
+
+#ifdef DEBUG
+    sudo_warnx("your old context was %s", se_state.old_context);
+#endif
+    se_state.new_context = get_exec_context(se_state.old_context, role, type);
+    if (!se_state.new_context) {
+#ifdef HAVE_LINUX_AUDIT
+	audit_role_change(se_state.old_context, "?",
+	  se_state.ttyn, 0);
+#endif
+	goto done;
+    }
+    
+    if (relabel_tty(ttyn, ptyfd) < 0) {
+	sudo_warn(U_("unable to set tty context to %s"), se_state.new_context);
+	goto done;
+    }
+
+#ifdef DEBUG
+    if (se_state.ttyfd != -1) {
+	sudo_warnx("your old tty context is %s", se_state.tty_context);
+	sudo_warnx("your new tty context is %s", se_state.new_tty_context);
+    }
+#endif
+
+#ifdef HAVE_LINUX_AUDIT
+    audit_role_change(se_state.old_context, se_state.new_context,
+	se_state.ttyn, 1);
+#endif
+
+    ret = 0;
+
+done:
+    debug_return_int(ret);
+}
+
+void
+selinux_execve(int fd, const char *path, char *const argv[], char *envp[],
+    bool noexec)
+{
+    char **nargv;
+    const char *sesh;
+    int argc, nargc, serrno;
+    debug_decl(selinux_execve, SUDO_DEBUG_SELINUX)
+
+    sesh = sudo_conf_sesh_path();
+    if (sesh == NULL) {
+	sudo_warnx("internal error: sesh path not set");
+	errno = EINVAL;
+	debug_return;
+    }
+
+    if (setexeccon(se_state.new_context)) {
+	sudo_warn(U_("unable to set exec context to %s"), se_state.new_context);
+	if (se_state.enforcing)
+	    debug_return;
+    }
+
+#ifdef HAVE_SETKEYCREATECON
+    if (setkeycreatecon(se_state.new_context)) {
+	sudo_warn(U_("unable to set key creation context to %s"), se_state.new_context);
+	if (se_state.enforcing)
+	    debug_return;
+    }
+#endif /* HAVE_SETKEYCREATECON */
+
+    /*
+     * Build new argv with sesh as argv[0].
+     * If argv[0] ends in -noexec, sesh will disable execute
+     * for the command it runs.
+     */
+    for (argc = 0; argv[argc] != NULL; argc++)
+	continue;
+    nargv = reallocarray(NULL, argc + 3, sizeof(char *));
+    if (nargv == NULL) {
+	sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+	debug_return;
+    }
+    if (noexec)
+	nargv[0] = *argv[0] == '-' ? "-sesh-noexec" : "sesh-noexec";
+    else
+	nargv[0] = *argv[0] == '-' ? "-sesh" : "sesh";
+    nargc = 1;
+    if (fd != -1 && asprintf(&nargv[nargc++], "--execfd=%d", fd) == -1) {
+	sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+	debug_return;
+    }
+    nargv[nargc++] = (char *)path;
+    memcpy(&nargv[nargc], &argv[1], argc * sizeof(char *)); /* copies NULL */
+
+    /* sesh will handle noexec for us. */
+    sudo_execve(-1, sesh, nargv, envp, false);
+    serrno = errno;
+    free(nargv);
+    errno = serrno;
+    debug_return;
+}
+
+#endif /* HAVE_SELINUX */