util: when unescaping strings, don't allow smuggling in of additional NUL bytes

[elogind.git] / src / shared / util.c

diff --git a/src/shared/util.c b/src/shared/util.c
index dbdb69270de7a7db7163397ff5df9a2e08f4ef17..4ad3f203d7d3f1b268b1044732cea6dac745e638 100644 (file)
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -280,6 +280,14 @@ int parse_uid(const char *s, uid_t* ret_uid) {
         if ((unsigned long) uid != ul)
                 return -ERANGE;
 
+        /* Some libc APIs use (uid_t) -1 as special placeholder */
+        if (uid == (uid_t) 0xFFFFFFFF)
+                return -ENXIO;
+
+        /* A long time ago UIDs where 16bit, hence explicitly avoid the 16bit -1 too */
+        if (uid == (uid_t) 0xFFFF)
+                return -ENXIO;
+
         *ret_uid = uid;
         return 0;
 }
@@ -1248,7 +1256,7 @@ char *cunescape_length_with_prefix(const char *s, size_t length, const char *pre
                         a = unhexchar(f[1]);
                         b = unhexchar(f[2]);
 
-                        if (a < 0 || b < 0) {
+                        if (a < 0 || b < 0 || (a == 0 && b == 0)) {
                                 /* Invalid escape code, let's take it literal then */
                                 *(t++) = '\\';
                                 *(t++) = 'x';
@@ -1275,7 +1283,7 @@ char *cunescape_length_with_prefix(const char *s, size_t length, const char *pre
                         b = unoctchar(f[1]);
                         c = unoctchar(f[2]);
 
-                        if (a < 0 || b < 0 || c < 0) {
+                        if (a < 0 || b < 0 || c < 0 || (a == 0 && b == 0 && c == 0)) {
                                 /* Invalid escape code, let's take it literal then */
                                 *(t++) = '\\';
                                 *(t++) = f[0];
@@ -1440,7 +1448,7 @@ _pure_ static bool fd_in_set(int fd, const int fdset[], unsigned n_fdset) {
 }
 
 int close_all_fds(const int except[], unsigned n_except) {
-        DIR *d;
+        _cleanup_closedir_ DIR *d = NULL;
         struct dirent *de;
         int r = 0;
 
@@ -1495,7 +1503,6 @@ int close_all_fds(const int except[], unsigned n_except) {
                 }
         }
 
-        closedir(d);
         return r;
 }
 
@@ -1559,8 +1566,7 @@ int chvt(int vt) {
 
 int read_one_char(FILE *f, char *ret, usec_t t, bool *need_nl) {
         struct termios old_termios, new_termios;
-        char c;
-        char line[LINE_MAX];
+        char c, line[LINE_MAX];
 
         assert(f);
         assert(ret);
@@ -1597,9 +1603,10 @@ int read_one_char(FILE *f, char *ret, usec_t t, bool *need_nl) {
                 }
         }
 
-        if (t != (usec_t) -1)
+        if (t != (usec_t) -1) {
                 if (fd_wait_for_event(fileno(f), POLLIN, t) <= 0)
                         return -ETIMEDOUT;
+        }
 
         if (!fgets(line, sizeof(line), f))
                 return -EIO;
@@ -1617,6 +1624,7 @@ int read_one_char(FILE *f, char *ret, usec_t t, bool *need_nl) {
 }
 
 int ask(char *ret, const char *replies, const char *text, ...) {
+        int r;
 
         assert(ret);
         assert(replies);
@@ -1625,7 +1633,6 @@ int ask(char *ret, const char *replies, const char *text, ...) {
         for (;;) {
                 va_list ap;
                 char c;
-                int r;
                 bool need_nl = true;
 
                 if (on_tty())
@@ -3475,6 +3482,17 @@ int wait_for_terminate(pid_t pid, siginfo_t *status) {
         }
 }
 
+/*
+ * Return values:
+ * < 0 : wait_for_terminate() failed to get the state of the
+ *       process, the process was terminated by a signal, or
+ *       failed for an unknown reason.
+ * >=0 : The process terminated normally, and its exit code is
+ *       returned.
+ *
+ * That is, success is indicated by a return value of zero, and an
+ * error is indicated by a non-zero value.
+ */
 int wait_for_terminate_and_warn(const char *name, pid_t pid) {
         int r;
         siginfo_t status;
@@ -5208,8 +5226,8 @@ int get_home_dir(char **_h) {
         assert(_h);
 
         /* Take the user specified one */
-        e = getenv("HOME");
-        if (e) {
+        e = secure_getenv("HOME");
+        if (e && path_is_absolute(e)) {
                 h = strdup(e);
                 if (!h)
                         return -ENOMEM;
@@ -6714,3 +6732,18 @@ char *tempfn_random(const char *p) {
 
         return t;
 }
+
+/* make sure the hostname is not "localhost" */
+bool is_localhost(const char *hostname) {
+        assert(hostname);
+
+        /* This tries to identify local hostnames described in RFC6761
+         * plus the redhatism of .localdomain */
+
+        return streq(hostname, "localhost") ||
+               streq(hostname, "localhost.") ||
+               endswith(hostname, ".localhost") ||
+               endswith(hostname, ".localhost.") ||
+               endswith(hostname, ".localdomain") ||
+               endswith(hostname, ".localdomain.");
+}