tree-wide: use ASSERT_PTR more

[thirdparty/systemd.git] / src / shared / exec-util.c

diff --git a/src/shared/exec-util.c b/src/shared/exec-util.c
index 68e896a8faebb089b0cb34804126493d10e9bec5..19ddf0498625d72bd973a68ee4af3475b86c8bfe 100644 (file)
--- a/src/shared/exec-util.c
+++ b/src/shared/exec-util.c
@@ -50,7 +50,7 @@ static int do_spawn(const char *path, char *argv[], int stdout_fd, pid_t *pid, b
                 char *_argv[2];
 
                 if (stdout_fd >= 0) {
-                        r = rearrange_stdio(STDIN_FILENO, stdout_fd, STDERR_FILENO);
+                        r = rearrange_stdio(STDIN_FILENO, TAKE_FD(stdout_fd), STDERR_FILENO);
                         if (r < 0)
                                 _exit(EXIT_FAILURE);
                 }
@@ -91,7 +91,6 @@ static int do_execute(
 
         _cleanup_hashmap_free_free_ Hashmap *pids = NULL;
         _cleanup_strv_free_ char **paths = NULL;
-        char **path, **e;
         int r;
         bool parallel_execution;
 
@@ -254,7 +253,7 @@ int execute_directories(
 }
 
 static int gather_environment_generate(int fd, void *arg) {
-        char ***env = arg, **x, **y;
+        char ***env = ASSERT_PTR(arg);
         _cleanup_fclose_ FILE *f = NULL;
         _cleanup_strv_free_ char **new = NULL;
         int r;
@@ -265,8 +264,6 @@ static int gather_environment_generate(int fd, void *arg) {
          * fd is always consumed, even on error.
          */
 
-        assert(env);
-
         f = fdopen(fd, "r");
         if (!f) {
                 safe_close(fd);
@@ -296,13 +293,11 @@ static int gather_environment_generate(int fd, void *arg) {
 
 static int gather_environment_collect(int fd, void *arg) {
         _cleanup_fclose_ FILE *f = NULL;
-        char ***env = arg;
+        char ***env = ASSERT_PTR(arg);
         int r;
 
         /* Write out a series of env=cescape(VAR=value) assignments to fd. */
 
-        assert(env);
-
         f = fdopen(fd, "w");
         if (!f) {
                 safe_close(fd);
@@ -322,13 +317,11 @@ static int gather_environment_collect(int fd, void *arg) {
 
 static int gather_environment_consume(int fd, void *arg) {
         _cleanup_fclose_ FILE *f = NULL;
-        char ***env = arg;
+        char ***env = ASSERT_PTR(arg);
         int r = 0;
 
         /* Read a series of env=cescape(VAR=value) assignments from fd into env. */
 
-        assert(env);
-
         f = fdopen(fd, "r");
         if (!f) {
                 safe_close(fd);
@@ -369,7 +362,6 @@ static int gather_environment_consume(int fd, void *arg) {
 
 int exec_command_flags_from_strv(char **ex_opts, ExecCommandFlags *flags) {
         ExecCommandFlags ex_flag, ret_flags = 0;
-        char **opt;
 
         assert(flags);
 
@@ -449,7 +441,16 @@ ExecCommandFlags exec_command_flags_from_string(const char *s) {
 }
 
 int fexecve_or_execve(int executable_fd, const char *executable, char *const argv[], char *const envp[]) {
+        /* Refuse invalid fds, regardless if fexecve() use is enabled or not */
+        if (executable_fd < 0)
+                return -EBADF;
+
+        /* Block any attempts on exploiting Linux' liberal argv[] handling, i.e. CVE-2021-4034 and suchlike */
+        if (isempty(executable) || strv_isempty(argv))
+                return -EINVAL;
+
 #if ENABLE_FEXECVE
+
         execveat(executable_fd, "", argv, envp, AT_EMPTY_PATH);
 
         if (IN_SET(errno, ENOSYS, ENOENT) || ERRNO_IS_PRIVILEGE(errno))
@@ -471,7 +472,7 @@ int fexecve_or_execve(int executable_fd, const char *executable, char *const arg
         return -errno;
 }
 
-int fork_agent(const char *name, int except[], size_t n_except, pid_t *ret_pid, const char *path, ...) {
+int fork_agent(const char *name, const int except[], size_t n_except, pid_t *ret_pid, const char *path, ...) {
         bool stdout_is_tty, stderr_is_tty;
         size_t n, i;
         va_list ap;
@@ -506,21 +507,27 @@ int fork_agent(const char *name, int except[], size_t n_except, pid_t *ret_pid,
                  * stdin around. */
                 fd = open("/dev/tty", O_WRONLY);
                 if (fd < 0) {
-                        log_error_errno(errno, "Failed to open /dev/tty: %m");
-                        _exit(EXIT_FAILURE);
-                }
+                        if (errno != ENXIO) {
+                                log_error_errno(errno, "Failed to open /dev/tty: %m");
+                                _exit(EXIT_FAILURE);
+                        }
 
-                if (!stdout_is_tty && dup2(fd, STDOUT_FILENO) < 0) {
-                        log_error_errno(errno, "Failed to dup2 /dev/tty: %m");
-                        _exit(EXIT_FAILURE);
-                }
+                        /* If we get ENXIO here we have no controlling TTY even though stdout/stderr are
+                         * connected to a TTY. That's a weird setup, but let's handle it gracefully: let's
+                         * skip the forking of the agents, given the TTY setup is not in order. */
+                } else {
+                        if (!stdout_is_tty && dup2(fd, STDOUT_FILENO) < 0) {
+                                log_error_errno(errno, "Failed to dup2 /dev/tty: %m");
+                                _exit(EXIT_FAILURE);
+                        }
 
-                if (!stderr_is_tty && dup2(fd, STDERR_FILENO) < 0) {
-                        log_error_errno(errno, "Failed to dup2 /dev/tty: %m");
-                        _exit(EXIT_FAILURE);
-                }
+                        if (!stderr_is_tty && dup2(fd, STDERR_FILENO) < 0) {
+                                log_error_errno(errno, "Failed to dup2 /dev/tty: %m");
+                                _exit(EXIT_FAILURE);
+                        }
 
-                safe_close_above_stdio(fd);
+                        fd = safe_close_above_stdio(fd);
+                }
         }
 
         (void) rlimit_nofile_safe();