pulseaudio: use env variable fallback in more cases

setting the PULSE_CLIENTCONFIG environment variable to the unmounted
file is a safe fallback, use it in more cases when mounting is considered
not an option

1 files changed, 60 insertions, 110 deletions

diff --git a/src/firejail/pulseaudio.c b/src/firejail/pulseaudio.c
index 4ddaba7ed..ce1692ba2 100644
--- a/src/firejail/pulseaudio.c
+++ b/src/firejail/pulseaudio.c
@@ -102,124 +102,74 @@ void pulseaudio_init(void) {
         if (set_perms(RUN_PULSE_DIR, getuid(), getgid(), 0700))
                 errExit("set_perms");
 
-        // create ~/.config/pulse directory if not present
-        char *dir1;
-        if (asprintf(&dir1, "%s/.config", cfg.homedir) == -1)
-                errExit("asprintf");
-        if (lstat(dir1, &s) == -1) {
-                pid_t child = fork();
-                if (child < 0)
-                        errExit("fork");
-                if (child == 0) {
-                        // drop privileges
-                        drop_privs(0);
-
-                        int rv = mkdir(dir1, 0755);
-                        if (rv == 0) {
-                                if (chmod(dir1, 0755))
-                                        {;} // do nothing
-                        }
-#ifdef HAVE_GCOV
-                        __gcov_flush();
-#endif
-                        _exit(0);
-                }
-                // wait for the child to finish
-                waitpid(child, NULL, 0);
-                fs_logger2("create", dir1);
-        }
-        else {
-                // we expect a user owned directory
-                if (!S_ISDIR(s.st_mode) || s.st_uid != getuid()) {
-                        if (S_ISLNK(s.st_mode))
-                                fprintf(stderr, "Error: user .config is a symbolic link\n");
-                        else
-                                fprintf(stderr, "Error: user .config is not a directory owned by the current user\n");
-                        exit(1);
-                }
-        }
-        free(dir1);
-
-        if (asprintf(&dir1, "%s/.config/pulse", cfg.homedir) == -1)
+        // create ~/.config directory if necessary
+        char *homeusercfg;
+        if (asprintf(&homeusercfg, "%s/.config", cfg.homedir) == -1)
                 errExit("asprintf");
-        if (lstat(dir1, &s) == -1) {
-                pid_t child = fork();
-                if (child < 0)
-                        errExit("fork");
-                if (child == 0) {
-                        // drop privileges
-                        drop_privs(0);
-
-                        int rv = mkdir(dir1, 0700);
-                        if (rv == 0) {
-                                if (chmod(dir1, 0700))
-                                        {;} // do nothing
-                        }
-#ifdef HAVE_GCOV
-                        __gcov_flush();
-#endif
-                        _exit(0);
-                }
-                // wait for the child to finish
-                waitpid(child, NULL, 0);
-                fs_logger2("create", dir1);
-        }
-        else {
-                // we expect a user owned directory
-                if (!S_ISDIR(s.st_mode) || s.st_uid != getuid()) {
-                        if (S_ISLNK(s.st_mode))
-                                fprintf(stderr, "Error: user .config/pulse is a symbolic link\n");
-                        else
-                                fprintf(stderr, "Error: user .config/pulse is not a directory owned by the current user\n");
-                        exit(1);
-                }
+        create_empty_dir_as_user(homeusercfg, 0700);
+        // set environment variable if creating ~/.config wasn't successful or if it is not a directory owned by the user
+        if (lstat(homeusercfg, &s) != 0 || !S_ISDIR(s.st_mode) || s.st_uid != getuid()) {
+                if (arg_debug)
+                        printf("Setting PULSE_CLIENTCONFIG environment variable\n");
+                if (setenv("PULSE_CLIENTCONFIG", pulsecfg, 1) < 0)
+                        errExit("setenv");
+                free(homeusercfg);
+                free(pulsecfg);
+                return;
         }
-        free(dir1);
+        free(homeusercfg);
 
-        // if we have ~/.config/pulse mount the new directory, else set environment variable.
-        char *homeusercfg;
+        // create ~/.config/pulse directory if necessary
         if (asprintf(&homeusercfg, "%s/.config/pulse", cfg.homedir) == -1)
                 errExit("asprintf");
-        if (stat(homeusercfg, &s) == 0) {
-                // get a file descriptor for ~/.config/pulse, fails if there is any symlink
-                int fd = safe_fd(homeusercfg, O_PATH|O_DIRECTORY|O_NOFOLLOW|O_CLOEXEC);
-                if (fd == -1)
-                        errExit("safe_fd");
-                // confirm the actual mount destination is owned by the user
-                if (fstat(fd, &s) == -1 || s.st_uid != getuid())
-                        errExit("fstat");
-                // preserve a read-only mount
-                struct statvfs vfs;
-                if (fstatvfs(fd, &vfs) == -1)
-                        errExit("fstatvfs");
-                if ((vfs.f_flag & MS_RDONLY) == MS_RDONLY)
-                        fs_rdonly(RUN_PULSE_DIR);
-                // mount via the link in /proc/self/fd
-                char *proc;
-                if (asprintf(&proc, "/proc/self/fd/%d", fd) == -1)
-                        errExit("asprintf");
-                if (mount(RUN_PULSE_DIR, proc, "none", MS_BIND, NULL) < 0)
-                        errExit("mount pulseaudio");
-                fs_logger2("tmpfs", homeusercfg);
-                free(proc);
-                close(fd);
-                // check /proc/self/mountinfo to confirm the mount is ok
-                MountData *mptr = get_last_mount();
-                if (strcmp(mptr->dir, homeusercfg) != 0 || strcmp(mptr->fstype, "tmpfs") != 0)
-                        errLogExit("invalid pulseaudio mount");
-
-                char *p;
-                if (asprintf(&p, "%s/client.conf", homeusercfg) == -1)
-                        errExit("asprintf");
-                fs_logger2("create", p);
-                free(p);
-        }
-
-        else {
-                // set environment
+        create_empty_dir_as_user(homeusercfg, 0700);
+        // set environment variable if creating ~/.config/pulse wasn't successful or if it is not a directory owned by the user
+        if (lstat(homeusercfg, &s) != 0 || !S_ISDIR(s.st_mode) || s.st_uid != getuid()) {
+                if (arg_debug)
+                        printf("Setting PULSE_CLIENTCONFIG environment variable\n");
                 if (setenv("PULSE_CLIENTCONFIG", pulsecfg, 1) < 0)
                         errExit("setenv");
+                free(homeusercfg);
+                free(pulsecfg);
+                return;
+        }
+
+        // get a file descriptor for ~/.config/pulse, fails if there is any symlink
+        int fd = safe_fd(homeusercfg, O_PATH|O_DIRECTORY|O_NOFOLLOW|O_CLOEXEC);
+        if (fd == -1)
+                errExit("safe_fd");
+        // confirm again the actual mount destination is owned by the user
+        if (fstat(fd, &s) == -1)
+                errExit("fstat");
+        if (s.st_uid != getuid()) {
+                fprintf(stderr, "Error: %s is not owned by the current user\n", homeusercfg);
+                exit(1);
         }
+        // preserve a read-only mount
+        struct statvfs vfs;
+        if (fstatvfs(fd, &vfs) == -1)
+                errExit("fstatvfs");
+        if ((vfs.f_flag & MS_RDONLY) == MS_RDONLY)
+                fs_rdonly(RUN_PULSE_DIR);
+        // mount via the link in /proc/self/fd
+        char *proc;
+        if (asprintf(&proc, "/proc/self/fd/%d", fd) == -1)
+                errExit("asprintf");
+        if (mount(RUN_PULSE_DIR, proc, "none", MS_BIND, NULL) < 0)
+                errExit("mount pulseaudio");
+        free(proc);
+        close(fd);
+        // check /proc/self/mountinfo to confirm the mount is ok
+        MountData *mptr = get_last_mount();
+        if (strcmp(mptr->dir, homeusercfg) != 0 || strcmp(mptr->fstype, "tmpfs") != 0)
+                errLogExit("invalid pulseaudio mount");
+        fs_logger2("tmpfs", homeusercfg);
+
+        char *p;
+        if (asprintf(&p, "%s/client.conf", homeusercfg) == -1)
+                errExit("asprintf");
+        fs_logger2("create", p);
+        free(p);
 
         free(pulsecfg);
         free(homeusercfg);