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Modernize chroot(8).

This commit is contained in:
Jonas 'Sortie' Termansen 2024-06-16 20:15:31 +00:00
parent 5d18d8be30
commit 49bf6298a7
1 changed files with 64 additions and 46 deletions
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62
utils/chroot.c
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@ -1,5 +1,5 @@
/* /*
* Copyright (c) 2013, 2015, 2023 Jonas 'Sortie' Termansen. * Copyright (c) 2013, 2015, 2023, 2024 Jonas 'Sortie' Termansen.
* *
* Permission to use, copy, modify, and distribute this software for any * Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above * purpose with or without fee is hereby granted, provided that the above
@ -91,14 +91,13 @@ int main(int argc, char* argv[])
if ( argc < 2 ) if ( argc < 2 )
error(1, 0, "missing operand, expected new root directory"); error(1, 0, "missing operand, expected new root directory");
if ( devices ) bool need_cleanup = devices;
// TODO: Why do we even have signal handling instead of just blocking the
// signals and waiting for the subprocess to react?
if ( need_cleanup )
{ {
if ( asprintf(&mount_point_dev, "%s/dev", argv[1]) < 0 )
error(1, errno, "asprintf: `%s/dev'", argv[1]);
// Create a device directory in the root filesystem.
mkdir(mount_point_dev, 0755);
struct sigaction sa; struct sigaction sa;
memset(&sa, 0, sizeof(sa)); memset(&sa, 0, sizeof(sa));
sa.sa_handler = unmount_handler; sa.sa_handler = unmount_handler;
@ -107,6 +106,15 @@ int main(int argc, char* argv[])
sigaction(SIGINT, &sa, NULL); sigaction(SIGINT, &sa, NULL);
sigaction(SIGQUIT, &sa, NULL); sigaction(SIGQUIT, &sa, NULL);
sigaction(SIGTERM, &sa, NULL); sigaction(SIGTERM, &sa, NULL);
}
if ( devices )
{
if ( asprintf(&mount_point_dev, "%s/dev", argv[1]) < 0 )
error(1, errno, "asprintf: `%s/dev'", argv[1]);
// Create a device directory in the root filesystem.
mkdir(mount_point_dev, 0755);
// Mount the current device directory inside the new root filesystem. // Mount the current device directory inside the new root filesystem.
int old_dev_fd = open("/dev", O_DIRECTORY | O_RDONLY); int old_dev_fd = open("/dev", O_DIRECTORY | O_RDONLY);
@ -114,15 +122,20 @@ int main(int argc, char* argv[])
fsm_fsbind(old_dev_fd, new_dev_fd, 0); fsm_fsbind(old_dev_fd, new_dev_fd, 0);
close(new_dev_fd); close(new_dev_fd);
close(old_dev_fd); close(old_dev_fd);
}
sigset_t oldset, sigs; sigset_t oldset, sigs;
if ( need_cleanup )
{
sigemptyset(&sigs); sigemptyset(&sigs);
sigaddset(&sigs, SIGHUP); sigaddset(&sigs, SIGHUP);
sigaddset(&sigs, SIGINT); sigaddset(&sigs, SIGINT);
sigaddset(&sigs, SIGQUIT); sigaddset(&sigs, SIGQUIT);
sigaddset(&sigs, SIGTERM); sigaddset(&sigs, SIGTERM);
sigprocmask(SIG_BLOCK, &sigs, &oldset); sigprocmask(SIG_BLOCK, &sigs, &oldset);
pid_t child_pid = fork(); }
pid_t child_pid = need_cleanup ? fork() : 0;
if ( child_pid < 0 ) if ( child_pid < 0 )
{ {
int errnum = errno; int errnum = errno;
@ -131,20 +144,11 @@ int main(int argc, char* argv[])
sigprocmask(SIG_SETMASK, &oldset, NULL); sigprocmask(SIG_SETMASK, &oldset, NULL);
error(1, errnum, "fork"); error(1, errnum, "fork");
} }
if ( child_pid != 0 )
if ( !child_pid )
{
if ( need_cleanup )
{ {
sigprocmask(SIG_SETMASK, &oldset, NULL);
int code;
waitpid(child_pid, &code, 0);
sigprocmask(SIG_BLOCK, &sigs, &oldset);
unmount(mount_point_dev, 0);
sigprocmask(SIG_SETMASK, &oldset, NULL);
mount_point_dev = NULL;
if ( WIFEXITED(code) )
return WEXITSTATUS(code);
raise(WTERMSIG(code));
return 128 + WTERMSIG(code);
}
signal(SIGHUP, SIG_DFL); signal(SIGHUP, SIG_DFL);
signal(SIGINT, SIG_DFL); signal(SIGINT, SIG_DFL);
signal(SIGQUIT, SIG_DFL); signal(SIGQUIT, SIG_DFL);
@ -165,4 +169,18 @@ int main(int argc, char* argv[])
error(0, errno, "`%s'", exec_argv[0]); error(0, errno, "`%s'", exec_argv[0]);
_exit(127); _exit(127);
}
sigprocmask(SIG_SETMASK, &oldset, NULL);
int code;
waitpid(child_pid, &code, 0);
sigprocmask(SIG_BLOCK, &sigs, &oldset);
if ( devices )
unmount(mount_point_dev, 0);
sigprocmask(SIG_SETMASK, &oldset, NULL);
mount_point_dev = NULL;
if ( WIFEXITED(code) )
return WEXITSTATUS(code);
raise(WTERMSIG(code));
return 128 + WTERMSIG(code);
} }