106 lines
3.1 KiB
C
106 lines
3.1 KiB
C
#define _GNU_SOURCE
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#include <grp.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <pwd.h>
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#include <sys/stat.h>
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#include <sys/mount.h>
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#include <sys/wait.h>
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#include <fcntl.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/fsuid.h>
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#include <gui-fatal.h>
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#include <errno.h>
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#include <libqubes-rpc-filecopy.h>
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#define INCOMING_DIR_NAME "QubesIncoming"
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char *prepare_creds_return_dir(int uid)
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{
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const struct passwd *pwd;
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pwd = getpwuid(uid);
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if (!pwd) {
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perror("getpwuid");
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exit(1);
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}
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setenv("HOME", pwd->pw_dir, 1);
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setenv("USER", pwd->pw_name, 1);
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if (setgid(pwd->pw_gid) < 0)
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gui_fatal("Error setting group permissions");
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if (initgroups(pwd->pw_name, pwd->pw_gid) < 0)
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gui_fatal("Error initializing groups");
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if (setfsuid(pwd->pw_uid) < 0)
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gui_fatal("Error setting filesystem level permissions");
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return pwd->pw_dir;
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}
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int main(int argc __attribute((__unused__)), char ** argv __attribute__((__unused__)))
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{
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char *home_dir;
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char *incoming_dir_root;
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char *incoming_dir;
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int uid, ret;
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pid_t pid;
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const char *remote_domain;
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char *procdir_path;
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int procfs_fd;
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uid = getuid();
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home_dir = prepare_creds_return_dir(uid);
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remote_domain = getenv("QREXEC_REMOTE_DOMAIN");
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if (!remote_domain) {
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gui_fatal("Cannot get remote domain name");
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}
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if (asprintf(&incoming_dir_root, "%s/%s", home_dir, INCOMING_DIR_NAME) < 0) {
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gui_fatal("Error allocating memory");
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}
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mkdir(incoming_dir_root, 0700);
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if (asprintf(&incoming_dir, "%s/%s", incoming_dir_root, remote_domain) < 0)
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gui_fatal("Error allocating memory");
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mkdir(incoming_dir, 0700);
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if (chdir(incoming_dir))
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gui_fatal("Error chdir to %s", incoming_dir);
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if (mount(".", ".", NULL, MS_BIND | MS_NODEV | MS_NOEXEC | MS_NOSUID, NULL) < 0)
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gui_fatal("Failed to mount a directory %s", incoming_dir);
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/* parse the input in unprivileged child process, parent will hold root
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* access to unmount incoming dir */
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switch (pid=fork()) {
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case -1:
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gui_fatal("Failed to create new process");
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case 0:
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if (asprintf(&procdir_path, "/proc/%d/fd", getpid()) < 0) {
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gui_fatal("Error allocating memory");
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}
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procfs_fd = open(procdir_path, O_DIRECTORY | O_RDONLY);
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if (procfs_fd < 0)
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perror("Failed to open /proc");
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else
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set_procfs_fd(procfs_fd);
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free(procdir_path);
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if (chroot("."))
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gui_fatal("Error chroot to %s", incoming_dir);
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if (setuid(uid) < 0) {
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/* no kdialog inside chroot */
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perror("setuid");
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exit(1);
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}
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return do_unpack();
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}
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if (waitpid(pid, &ret, 0) < 0) {
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gui_fatal("Failed to wait for child process");
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}
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if (umount2(".", MNT_DETACH) < 0)
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gui_fatal("Cannot umount incoming directory");
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if (!WIFEXITED(ret)) {
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gui_fatal("Child process exited abnormally");
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}
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return WEXITSTATUS(ret);
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}
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