passt/pasta contains a number of routines designed to isolate passt from
the rest of the system for security. These are spread through util.c and
passt.c. Move them together into a new isolation.c file.
Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au>
---
Makefile | 8 +--
conf.c | 1 +
isolation.c | 167 ++++++++++++++++++++++++++++++++++++++++++++++++++++
isolation.h | 15 +++++
passt.c | 113 +----------------------------------
pasta.c | 1 +
util.c | 51 ----------------
util.h | 2 -
8 files changed, 189 insertions(+), 169 deletions(-)
create mode 100644 isolation.c
create mode 100644 isolation.h
diff --git a/Makefile b/Makefile
index 644a541..af3d1ff 100644
--- a/Makefile
+++ b/Makefile
@@ -32,16 +32,16 @@ CFLAGS += -DRLIMIT_STACK_VAL=$(RLIMIT_STACK_VAL)
CFLAGS += -DARCH=\"$(TARGET_ARCH)\"
PASST_SRCS = arch.c arp.c checksum.c conf.c dhcp.c dhcpv6.c icmp.c igmp.c \
- lineread.c mld.c ndp.c netlink.c packet.c passt.c pasta.c pcap.c \
- siphash.c tap.c tcp.c tcp_splice.c udp.c util.c
+ isolation.c lineread.c mld.c ndp.c netlink.c packet.c passt.c pasta.c \
+ pcap.c siphash.c tap.c tcp.c tcp_splice.c udp.c util.c
QRAP_SRCS = qrap.c
SRCS = $(PASST_SRCS) $(QRAP_SRCS)
MANPAGES = passt.1 pasta.1 qrap.1
PASST_HEADERS = arch.h arp.h checksum.h conf.h dhcp.h dhcpv6.h icmp.h \
- lineread.h ndp.h netlink.h packet.h passt.h pasta.h pcap.h \
- siphash.h tap.h tcp.h tcp_splice.h udp.h util.h
+ isolation.h lineread.h ndp.h netlink.h packet.h passt.h pasta.h \
+ pcap.h siphash.h tap.h tcp.h tcp_splice.h udp.h util.h
HEADERS = $(PASST_HEADERS)
# On gcc 11.2, with -O2 and -flto, tcp_hash() and siphash_20b(), if inlined,
diff --git a/conf.c b/conf.c
index b669f5d..d9e7472 100644
--- a/conf.c
+++ b/conf.c
@@ -40,6 +40,7 @@
#include "tcp.h"
#include "pasta.h"
#include "lineread.h"
+#include "isolation.h"
/**
* get_bound_ports() - Get maps of ports with bound sockets
diff --git a/isolation.c b/isolation.c
new file mode 100644
index 0000000..41ca888
--- /dev/null
+++ b/isolation.c
@@ -0,0 +1,167 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+/* PASST - Plug A Simple Socket Transport
+ * for qemu/UNIX domain socket mode
+ *
+ * PASTA - Pack A Subtle Tap Abstraction
+ * for network namespace/tap device mode
+ *
+ * isolation.c - Self isolation helpers
+ *
+ * Copyright Red Hat
+ * Author: Stefano Brivio <sbrivio(a)redhat.com>
+ * Author: David Gibson <david(a)gibson.dropbear.id.au>
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <grp.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <pwd.h>
+#include <sched.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+#include <sys/mount.h>
+#include <sys/prctl.h>
+#include <sys/socket.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <netinet/if_ether.h>
+
+#include <linux/audit.h>
+#include <linux/capability.h>
+#include <linux/filter.h>
+#include <linux/seccomp.h>
+
+#include "util.h"
+#include "seccomp.h"
+#include "passt.h"
+#include "isolation.h"
+
+/**
+ * drop_caps() - Drop capabilities we might have except for CAP_NET_BIND_SERVICE
+ */
+void drop_caps(void)
+{
+ int i;
+
+ for (i = 0; i < 64; i++) {
+ if (i == CAP_NET_BIND_SERVICE)
+ continue;
+
+ prctl(PR_CAPBSET_DROP, i, 0, 0, 0);
+ }
+}
+
+/**
+ * drop_root() - Switch to given UID and GID
+ * @uid: User ID to switch to
+ * @gid: Group ID to switch to
+ */
+void drop_root(uid_t uid, gid_t gid)
+{
+ if (setgroups(0, NULL)) {
+ /* If we don't start with CAP_SETGID, this will EPERM */
+ if (errno != EPERM) {
+ err("Can't drop supplementary groups: %s",
+ strerror(errno));
+ exit(EXIT_FAILURE);
+ }
+ }
+
+ if (!setgid(gid) && !setuid(uid))
+ return;
+
+ err("Can't change user/group, exiting");
+ exit(EXIT_FAILURE);
+}
+
+/**
+ * sandbox() - Unshare IPC, mount, PID, UTS, and user namespaces, "unmount"
root
+ *
+ * Return: negative error code on failure, zero on success
+ */
+int sandbox(struct ctx *c)
+{
+ int flags = CLONE_NEWIPC | CLONE_NEWNS | CLONE_NEWUTS;
+
+ if (!c->netns_only) {
+ if (c->pasta_userns_fd == -1)
+ flags |= CLONE_NEWUSER;
+ else
+ setns(c->pasta_userns_fd, CLONE_NEWUSER);
+ }
+
+ c->pasta_userns_fd = -1;
+
+ /* If we run in foreground, we have no chance to actually move to a new
+ * PID namespace. For passt, use CLONE_NEWPID anyway, in case somebody
+ * ever gets around seccomp profiles -- there's no harm in passing it.
+ */
+ if (!c->foreground || c->mode == MODE_PASST)
+ flags |= CLONE_NEWPID;
+
+ if (unshare(flags)) {
+ perror("unshare");
+ return -errno;
+ }
+
+ if (mount("", "/", "", MS_UNBINDABLE | MS_REC, NULL)) {
+ perror("mount /");
+ return -errno;
+ }
+
+ if (mount("", TMPDIR, "tmpfs",
+ MS_NODEV | MS_NOEXEC | MS_NOSUID | MS_RDONLY,
+ "nr_inodes=2,nr_blocks=0")) {
+ perror("mount tmpfs");
+ return -errno;
+ }
+
+ if (chdir(TMPDIR)) {
+ perror("chdir");
+ return -errno;
+ }
+
+ if (syscall(SYS_pivot_root, ".", ".")) {
+ perror("pivot_root");
+ return -errno;
+ }
+
+ if (umount2(".", MNT_DETACH | UMOUNT_NOFOLLOW)) {
+ perror("umount2");
+ return -errno;
+ }
+
+ drop_caps(); /* Relative to the new user namespace this time. */
+
+ return 0;
+}
+
+/**
+ * seccomp() - Set up seccomp filters depending on mode, won't return on failure
+ * @c: Execution context
+ */
+void seccomp(const struct ctx *c)
+{
+ struct sock_fprog prog;
+
+ if (c->mode == MODE_PASST) {
+ prog.len = (unsigned short)ARRAY_SIZE(filter_passt);
+ prog.filter = filter_passt;
+ } else {
+ prog.len = (unsigned short)ARRAY_SIZE(filter_pasta);
+ prog.filter = filter_pasta;
+ }
+
+ if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) ||
+ prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog)) {
+ perror("prctl");
+ exit(EXIT_FAILURE);
+ }
+}
diff --git a/isolation.h b/isolation.h
new file mode 100644
index 0000000..2540a35
--- /dev/null
+++ b/isolation.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: AGPL-3.0-or-later
+ * Copyright Red Hat
+ * Author: Stefano Brivio <sbrivio(a)redhat.com>
+ * Author: David Gibson <david(a)gibson.dropbear.id.au>
+ */
+
+#ifndef ISOLATION_H
+#define ISOLATION_H
+
+void drop_caps(void);
+void drop_root(uid_t uid, gid_t gid);
+int sandbox(struct ctx *c);
+void seccomp(const struct ctx *c);
+
+#endif /* ISOLATION_H */
diff --git a/passt.c b/passt.c
index bbf53d9..2a8314c 100644
--- a/passt.c
+++ b/passt.c
@@ -19,51 +19,25 @@
* created in a separate network namespace).
*/
-#include <sched.h>
-#include <stdio.h>
#include <sys/epoll.h>
-#include <sys/socket.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <dirent.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/resource.h>
-#include <sys/uio.h>
-#include <sys/syscall.h>
-#include <sys/wait.h>
-#include <sys/mount.h>
-#include <netinet/ip.h>
-#include <net/ethernet.h>
-#include <libgen.h>
#include <stdlib.h>
#include <unistd.h>
-#include <net/if.h>
#include <netdb.h>
#include <string.h>
#include <errno.h>
#include <time.h>
#include <syslog.h>
-#include <sys/stat.h>
#include <sys/prctl.h>
-#include <stddef.h>
-#include <netinet/udp.h>
-#include <netinet/tcp.h>
#include <netinet/if_ether.h>
-#include <linux/seccomp.h>
-#include <linux/audit.h>
-#include <linux/filter.h>
-#include <linux/icmpv6.h>
-
#include "util.h"
-#include "seccomp.h"
#include "passt.h"
#include "dhcp.h"
#include "dhcpv6.h"
-#include "icmp.h"
-#include "tcp.h"
-#include "udp.h"
+#include "isolation.h"
#include "pcap.h"
#include "tap.h"
#include "conf.h"
@@ -166,91 +140,6 @@ void proto_update_l2_buf(const unsigned char *eth_d, const unsigned
char *eth_s,
udp_update_l2_buf(eth_d, eth_s, ip_da);
}
-/**
- * seccomp() - Set up seccomp filters depending on mode, won't return on failure
- * @c: Execution context
- */
-static void seccomp(const struct ctx *c)
-{
- struct sock_fprog prog;
-
- if (c->mode == MODE_PASST) {
- prog.len = (unsigned short)ARRAY_SIZE(filter_passt);
- prog.filter = filter_passt;
- } else {
- prog.len = (unsigned short)ARRAY_SIZE(filter_pasta);
- prog.filter = filter_pasta;
- }
-
- if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) ||
- prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog)) {
- perror("prctl");
- exit(EXIT_FAILURE);
- }
-}
-
-/**
- * sandbox() - Unshare IPC, mount, PID, UTS, and user namespaces, "unmount"
root
- *
- * Return: negative error code on failure, zero on success
- */
-static int sandbox(struct ctx *c)
-{
- int flags = CLONE_NEWIPC | CLONE_NEWNS | CLONE_NEWUTS;
-
- if (!c->netns_only) {
- if (c->pasta_userns_fd == -1)
- flags |= CLONE_NEWUSER;
- else
- setns(c->pasta_userns_fd, CLONE_NEWUSER);
- }
-
- c->pasta_userns_fd = -1;
-
- /* If we run in foreground, we have no chance to actually move to a new
- * PID namespace. For passt, use CLONE_NEWPID anyway, in case somebody
- * ever gets around seccomp profiles -- there's no harm in passing it.
- */
- if (!c->foreground || c->mode == MODE_PASST)
- flags |= CLONE_NEWPID;
-
- if (unshare(flags)) {
- perror("unshare");
- return -errno;
- }
-
- if (mount("", "/", "", MS_UNBINDABLE | MS_REC, NULL)) {
- perror("mount /");
- return -errno;
- }
-
- if (mount("", TMPDIR, "tmpfs",
- MS_NODEV | MS_NOEXEC | MS_NOSUID | MS_RDONLY,
- "nr_inodes=2,nr_blocks=0")) {
- perror("mount tmpfs");
- return -errno;
- }
-
- if (chdir(TMPDIR)) {
- perror("chdir");
- return -errno;
- }
-
- if (syscall(SYS_pivot_root, ".", ".")) {
- perror("pivot_root");
- return -errno;
- }
-
- if (umount2(".", MNT_DETACH | UMOUNT_NOFOLLOW)) {
- perror("umount2");
- return -errno;
- }
-
- drop_caps(); /* Relative to the new user namespace this time. */
-
- return 0;
-}
-
/**
* exit_handler() - Signal handler for SIGQUIT and SIGTERM
* @unused: Unused, handler deals with SIGQUIT and SIGTERM only
diff --git a/pasta.c b/pasta.c
index a844af2..0bdb655 100644
--- a/pasta.c
+++ b/pasta.c
@@ -40,6 +40,7 @@
#include "util.h"
#include "passt.h"
+#include "isolation.h"
#include "netlink.h"
/* PID of child, in case we created a namespace */
diff --git a/util.c b/util.c
index ce88aee..f709838 100644
--- a/util.c
+++ b/util.c
@@ -13,30 +13,17 @@
*/
#include <sched.h>
-#include <stdio.h>
-#include <stdint.h>
-#include <stddef.h>
#include <stdlib.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <net/ethernet.h>
-#include <net/if.h>
-#include <netinet/tcp.h>
-#include <netinet/udp.h>
#include <sys/epoll.h>
-#include <sys/prctl.h>
-#include <sys/types.h>
-#include <sys/stat.h>
#include <fcntl.h>
#include <syslog.h>
#include <stdarg.h>
#include <string.h>
#include <time.h>
#include <errno.h>
-#include <pwd.h>
-#include <grp.h>
-
-#include <linux/capability.h>
#include "util.h"
#include "passt.h"
@@ -467,44 +454,6 @@ void procfs_scan_listen(struct ctx *c, uint8_t proto, int ip_version,
int ns,
}
}
-/**
- * drop_caps() - Drop capabilities we might have except for CAP_NET_BIND_SERVICE
- */
-void drop_caps(void)
-{
- int i;
-
- for (i = 0; i < 64; i++) {
- if (i == CAP_NET_BIND_SERVICE)
- continue;
-
- prctl(PR_CAPBSET_DROP, i, 0, 0, 0);
- }
-}
-
-/**
- * drop_root() - Switch to given UID and GID
- * @uid: User ID to switch to
- * @gid: Group ID to switch to
- */
-void drop_root(uid_t uid, gid_t gid)
-{
- if (setgroups(0, NULL)) {
- /* If we don't start with CAP_SETGID, this will EPERM */
- if (errno != EPERM) {
- err("Can't drop supplementary groups: %s",
- strerror(errno));
- exit(EXIT_FAILURE);
- }
- }
-
- if (!setgid(gid) && !setuid(uid))
- return;
-
- err("Can't change user/group, exiting");
- exit(EXIT_FAILURE);
-}
-
/**
* ns_enter() - Enter configured user (unless already joined) and network ns
* @c: Execution context
diff --git a/util.h b/util.h
index 9626cb5..1003303 100644
--- a/util.h
+++ b/util.h
@@ -233,8 +233,6 @@ int bitmap_isset(const uint8_t *map, int bit);
char *line_read(char *buf, size_t len, int fd);
void procfs_scan_listen(struct ctx *c, uint8_t proto, int ip_version, int ns,
uint8_t *map, uint8_t *exclude);
-void drop_caps(void);
-void drop_root(uid_t uid, gid_t gid);
int ns_enter(const struct ctx *c);
void write_pidfile(int fd, pid_t pid);
int __daemon(int pidfile_fd, int devnull_fd);
--
2.37.3