shell selection

7 files changed, 90 insertions, 83 deletions

diff --git a/src/firejail/bandwidth.c b/src/firejail/bandwidth.c
index 34c5ca509..5ff67b644 100644
--- a/src/firejail/bandwidth.c
+++ b/src/firejail/bandwidth.c
@@ -459,13 +459,15 @@ void bandwidth_pid(pid_t pid, const char *command, const char *dev, int down, in
         if (setregid(0, 0))
                 errExit("setregid");
 
+        assert(cfg.shell);
+
         char *arg[4];
-        arg[0] = "/bin/bash";
+        arg[0] = cfg.shell;
         arg[1] = "-c";
         arg[2] = cmd;
         arg[3] = NULL;
-        execvp("/bin/bash", arg);
+        execvp(arg[0], arg);
         
         // it will never get here
-        exit(0);                
+        errExit("execvp");
 }
diff --git a/src/firejail/env.c b/src/firejail/env.c
index 79d6b81e3..fdfa80ea8 100644
--- a/src/firejail/env.c
+++ b/src/firejail/env.c
@@ -121,10 +121,6 @@ void env_defaults(void) {
                 errExit("setenv");
         if (setenv("container", "firejail", 1) < 0) // LXC sets container=lxc,
                 errExit("setenv");
-        if (arg_zsh && setenv("SHELL", "/usr/bin/zsh", 1) < 0)
-                errExit("setenv");
-        if (arg_csh && setenv("SHELL", "/bin/csh", 1) < 0)
-                errExit("setenv");
         if (cfg.shell && setenv("SHELL", cfg.shell, 1) < 0)
                 errExit("setenv");
         // set prompt color to green
diff --git a/src/firejail/firejail.h b/src/firejail/firejail.h
index 16b9d468f..0de2a354d 100644
--- a/src/firejail/firejail.h
+++ b/src/firejail/firejail.h
@@ -277,6 +277,7 @@ extern int fullargc;
 
 // main.c
 void check_user_namespace(void);
+char *guess_shell(void);
 
 // sandbox.c
 int sandbox(void* sandbox_arg);
diff --git a/src/firejail/fs.c b/src/firejail/fs.c
index bf78a2e3b..5fe31cec8 100644
--- a/src/firejail/fs.c
+++ b/src/firejail/fs.c
@@ -1110,14 +1110,13 @@ int fs_check_chroot_dir(const char *rootdir) {
         }
         free(name);
 
-        // check /bin/bash
-//      if (asprintf(&name, "%s/bin/bash", rootdir) == -1)
-//              errExit("asprintf");
-//      if (stat(name, &s) == -1) {
-//              fprintf(stderr, "Error: cannot find /bin/bash in chroot directory\n");
-//              return 1;
-//      }
-//      free(name);
+        // check shell
+        if (!arg_shell_none) {
+                if (stat(cfg.shell, &s) == -1) {
+                        fprintf(stderr, "Error: cannot find %s in chroot directory\n", cfg.shell);
+                        return 1;
+                }
+        }
 
         // check x11 socket directory
         if (getenv("FIREJAIL_X11")) {
diff --git a/src/firejail/join.c b/src/firejail/join.c
index 0b5b6a34a..80ed1dc51 100644
--- a/src/firejail/join.c
+++ b/src/firejail/join.c
@@ -330,32 +330,21 @@ void join(pid_t pid, int argc, char **argv, int index) {
                         }
                 }
 
-                // run cmdline trough /bin/bash
+                // run cmdline trough shell
                 if (cfg.command_line == NULL) {
+                        cfg.shell = guess_shell();
+                        if (!cfg.shell) {
+                                fprintf(stderr, "Error: unable to guess your shell, please set explicitly by using --shell option.\n");
+                                exit(1);
+                        }
+                        if (arg_debug)
+                                printf("Autoselecting %s as shell\n", cfg.shell);
 
                         // replace the process with a shell
-                        if (cfg.shell)
-                                        execlp(cfg.shell, cfg.shell, NULL);
-                                else if (arg_zsh)
-                                        execlp("/usr/bin/zsh", "/usr/bin/zsh", NULL);
-                                else if (arg_csh)
-                                        execlp("/bin/csh", "/bin/csh", NULL);
-                                else {
-                                        struct stat s;
-                                        if (stat("/bin/bash", &s) == 0)
-                                                execlp("/bin/bash", "/bin/bash", NULL);
-                                        else if (stat("/usr/bin/zsh", &s) == 0)
-                                                execlp("/usr/bin/zsh", "/usr/bin/zsh", NULL);
-                                        else if (stat("/bin/csh", &s) == 0)
-                                                execlp("/bin/csh", "/bin/csh", NULL);
-                                        else if (stat("/bin/sh", &s) == 0)
-                                                execlp("/bin/sh", "/bin/sh", NULL);
-                                }
+                        execlp(cfg.shell, cfg.shell, NULL);
                         
-                        // no shell found, print an error and exit
-                        fprintf(stderr, "Error: no POSIX shell found\n");
-                        sleep(5);
-                        exit(1);
+                        // it should never get here
+                        errExit("execlp");
                 }
                 else {
                         // run the command supplied by the user
@@ -398,19 +387,16 @@ void join(pid_t pid, int argc, char **argv, int index) {
                                 execvp(cfg.original_argv[cfg.original_program_index], &cfg.original_argv[cfg.original_program_index]);
                                 exit(1);
                         } else {
-                                // choose the shell requested by the user, or use bash as default
-                                char *sh;
-                                if (cfg.shell)
-                                        sh = cfg.shell;
-                                else if (arg_zsh)
-                                        sh = "/usr/bin/zsh";
-                                else if (arg_csh)
-                                        sh = "/bin/csh";
-                                else
-                                        sh = "/bin/bash";
-        
+//                              assert(cfg.shell);
+                                cfg.shell = guess_shell();
+                                if (!cfg.shell) {
+                                        fprintf(stderr, "Error: unable to guess your shell, please set explicitly by using --shell option.\n");
+                                        exit(1);
+                                }
+                                if (arg_debug)
+                                        printf("Autoselecting %s as shell\n", cfg.shell);
                                 char *arg[5];
-                                arg[0] = sh;
+                                arg[0] = cfg.shell;
                                 arg[1] = "-c";
                                 if (arg_debug)
                                         printf("Starting %s\n", cfg.command_line);
@@ -423,7 +409,10 @@ void join(pid_t pid, int argc, char **argv, int index) {
                                         arg[3] = cfg.command_line;
                                         arg[4] = NULL;
                                 }
-                                execvp("/bin/bash", arg);
+                                execvp(arg[0], arg);
+
+                                // it should never get here
+                                errExit("execvp");
                         }
                 }
 
diff --git a/src/firejail/main.c b/src/firejail/main.c
index acae7c3dd..8a4d627f3 100644
--- a/src/firejail/main.c
+++ b/src/firejail/main.c
@@ -709,6 +709,32 @@ static void detect_quiet(int argc, char **argv) {
         }
 }
 
+char *guess_shell(void) {
+        char *shell;
+        // shells in order of preference
+        char *shells[] = {"/bin/bash", "/bin/csh", "/usr/bin/zsh", "/bin/sh", "/bin/ash", NULL };
+
+        int i = 0;
+        while (shells[i] != NULL) {
+                struct stat s;
+                // access call checks as real UID/GID, not as effective UID/GID
+                if (stat(shells[i], &s) == 0 && access(shells[i], R_OK) == 0) {
+                        shell = shells[i];
+                        break;
+                }
+                i++;
+        }
+
+
+        // FIXME get rid of arg_csh and arg_zsh completely
+        if (strcmp(shell,"/bin/csh"))
+                arg_csh = 1;
+        if (strcmp(shell,"/usr/bin/zsh") || strcmp(shell,"/bin/zsh"))
+                arg_zsh = 1;
+
+        return shell;
+}
+
 //*******************************************
 // Main program
 //*******************************************
@@ -1857,26 +1883,28 @@ int main(int argc, char **argv) {
                                 fprintf(stderr, "Error: --shell=none was already specified.\n");
                                 return 1;
                         }
-                        if (arg_zsh || cfg.shell ) {
+                        if (cfg.shell) {
                                 fprintf(stderr, "Error: only one default user shell can be specified\n");
                                 return 1;
                         }
                         arg_csh = 1;
+                        cfg.shell = "/bin/csh";
                 }
                 else if (strcmp(argv[i], "--zsh") == 0) {
                         if (arg_shell_none) {
                                 fprintf(stderr, "Error: --shell=none was already specified.\n");
                                 return 1;
                         }
-                        if (arg_csh || cfg.shell ) {
+                        if (cfg.shell) {
                                 fprintf(stderr, "Error: only one default user shell can be specified\n");
                                 return 1;
                         }
                         arg_zsh = 1;
+                        cfg.shell = "/bin/zsh";
                 }
                 else if (strcmp(argv[i], "--shell=none") == 0) {
                         arg_shell_none = 1;
-                        if (arg_csh || arg_zsh || cfg.shell) {
+                        if (cfg.shell) {
                                 fprintf(stderr, "Error: a shell was already specified\n");
                                 return 1;
                         }
@@ -1888,7 +1916,7 @@ int main(int argc, char **argv) {
                         }
                         invalid_filename(argv[i] + 8);
                         
-                        if (arg_csh || arg_zsh || cfg.shell) {
+                        if (cfg.shell) {
                                 fprintf(stderr, "Error: only one user shell can be specified\n");
                                 return 1;
                         }
@@ -1970,27 +1998,24 @@ int main(int argc, char **argv) {
                 free(msg);
         }
 
-        // build the sandbox command
-        if (prog_index == -1 && arg_zsh) {
-                cfg.command_line = "/usr/bin/zsh";
-                cfg.window_title = "/usr/bin/zsh";
-                cfg.command_name = "zsh";
-        }
-        else if (prog_index == -1 && arg_csh) {
-                cfg.command_line = "/bin/csh";
-                cfg.window_title = "/bin/csh";
-                cfg.command_name = "csh";
+        // guess shell if unspecified
+//      if (!arg_shell_none && !cfg.shell) {
+        if (prog_index == -1 && !cfg.shell) {
+                cfg.shell = guess_shell();
+                if (!cfg.shell) {
+                        fprintf(stderr, "Error: unable to guess your shell, please set explicitly by using --shell option.\n");
+                        exit(1);
+                }
+                if (arg_debug)
+                        printf("Autoselecting %s as shell\n", cfg.shell);
         }
-        else if (prog_index == -1 && cfg.shell) {
+
+        // build the sandbox command
+        if (prog_index == -1 && cfg.shell) {
                 cfg.command_line = cfg.shell;
                 cfg.window_title = cfg.shell;
                 cfg.command_name = cfg.shell;
         }
-        else if (prog_index == -1) {
-                cfg.command_line = "/bin/bash";
-                cfg.window_title = "/bin/bash";
-                cfg.command_name = "bash";
-        }
         else if (arg_appimage) {
                 if (arg_debug)
                         printf("Configuring appimage environment\n");
@@ -2000,6 +2025,10 @@ int main(int argc, char **argv) {
         else {
                 build_cmdline(&cfg.command_line, &cfg.window_title, argc, argv, prog_index);
         }
+/*      else {
+                fprintf(stderr, "Error: command must be specified when --shell=none used.\n");
+                exit(1);
+        }*/
         
         assert(cfg.command_name);
         if (arg_debug)
diff --git a/src/firejail/sandbox.c b/src/firejail/sandbox.c
index a131d9e91..5451c6d6c 100644
--- a/src/firejail/sandbox.c
+++ b/src/firejail/sandbox.c
@@ -325,20 +325,11 @@ static void start_application(void) {
         // start the program using a shell
         //****************************************
         else {
-                // choose the shell requested by the user, or use bash as default
-                char *sh;
-                if (cfg.shell)
-                        sh = cfg.shell;
-                else if (arg_zsh)
-                        sh = "/usr/bin/zsh";
-                else if (arg_csh)
-                        sh = "/bin/csh";
-                else
-                        sh = "/bin/bash";
-                        
+                assert(cfg.shell);
+
                 char *arg[5];
                 int index = 0;
-                arg[index++] = sh;
+                arg[index++] = cfg.shell;
                 arg[index++] = "-c";
                 assert(cfg.command_line);
                 if (arg_debug)
@@ -368,7 +359,7 @@ static void start_application(void) {
                 
                 if (!arg_command && !arg_quiet)
                         printf("Child process initialized\n");
-                execvp(sh, arg);
+                execvp(arg[0], arg);
         }
         
         perror("execvp");