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-rw-r--r--plugins/sudoers/exptilde.c99
1 files changed, 99 insertions, 0 deletions
diff --git a/plugins/sudoers/exptilde.c b/plugins/sudoers/exptilde.c
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+++ b/plugins/sudoers/exptilde.c
@@ -0,0 +1,99 @@
+/*
+ * SPDX-License-Identifier: ISC
+ *
+ * Copyright (c) 2020 Todd C. Miller <Todd.Miller@sudo.ws>
+ *
+ * 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>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <grp.h>
+#include <pwd.h>
+
+#include "sudoers.h"
+#include "pwutil.h"
+
+/*
+ * Expand leading tilde in *path, which must be dynamically allocated.
+ * Replaces path with the expanded version as needed, freeing the old one.
+ * Returns true on success, false on failure.
+ */
+bool
+expand_tilde(char **path, const char *user)
+{
+ char *npath, *opath = *path;
+ char *slash = NULL;
+ struct passwd *pw;
+ int len;
+ debug_decl(expand_tilde, SUDOERS_DEBUG_UTIL);
+
+ switch (*opath++) {
+ case '/':
+ /* A fully-qualified path, nothing to do. */
+ debug_return_bool(true);
+ case '~':
+ /* See below. */
+ break;
+ default:
+ /* Not a fully-qualified path or one that starts with a tilde. */
+ debug_return_bool(false);
+ }
+
+ switch (*opath) {
+ case '\0':
+ /* format: ~ */
+ break;
+ case '/':
+ /* format: ~/foo */
+ opath++;
+ break;
+ default:
+ /* format: ~user/foo */
+ user = opath;
+ slash = strchr(opath, '/');
+ if (slash != NULL) {
+ *slash = '\0';
+ opath = slash + 1;
+ } else {
+ opath = (char *)"";
+ }
+ }
+ pw = sudo_getpwnam(user);
+ if (slash != NULL)
+ *slash = '/';
+ if (pw == NULL) {
+ /* Unknown user. */
+ sudo_warnx(U_("unknown user %s"), user);
+ debug_return_bool(false);
+ }
+
+ len = asprintf(&npath, "%s%s%s", pw->pw_dir, *opath ? "/" : "", opath);
+ sudo_pw_delref(pw);
+ if (len == -1) {
+ sudo_warnx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
+ debug_return_bool(false);
+ }
+
+ free(*path);
+ *path = npath;
+ debug_return_bool(true);
+}