forked from cyrillos/criu
/
parasite-syscall.c
794 lines (625 loc) · 18.2 KB
/
parasite-syscall.c
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#include <unistd.h>
#include <inttypes.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/mman.h>
#include "protobuf.h"
#include "protobuf/sa.pb-c.h"
#include "protobuf/itimer.pb-c.h"
#include "protobuf/creds.pb-c.h"
#include "protobuf/core.pb-c.h"
#include "protobuf/pagemap.pb-c.h"
#include "syscall.h"
#include "ptrace.h"
#include "asm/processor-flags.h"
#include "parasite-syscall.h"
#include "parasite-blob.h"
#include "parasite.h"
#include "crtools.h"
#include "namespaces.h"
#include "pstree.h"
#include "net.h"
#include "mem.h"
#include <string.h>
#include <stdlib.h>
#include "asm/parasite-syscall.h"
#include "asm/dump.h"
#define parasite_size (round_up(sizeof(parasite_blob), sizeof(long)))
static int can_run_syscall(unsigned long ip, unsigned long start, unsigned long end)
{
return ip >= start && ip < (end - code_syscall_size);
}
static int syscall_fits_vma_area(struct vma_area *vma_area)
{
return can_run_syscall((unsigned long)vma_area->vma.start,
(unsigned long)vma_area->vma.start,
(unsigned long)vma_area->vma.end);
}
static struct vma_area *get_vma_by_ip(struct list_head *vma_area_list, unsigned long ip)
{
struct vma_area *vma_area;
list_for_each_entry(vma_area, vma_area_list, list) {
if (vma_area->vma.start >= TASK_SIZE)
continue;
if (!(vma_area->vma.prot & PROT_EXEC))
continue;
if (syscall_fits_vma_area(vma_area))
return vma_area;
}
return NULL;
}
/* we run at @regs->ip */
int __parasite_execute(struct parasite_ctl *ctl, pid_t pid, user_regs_struct_t *regs)
{
siginfo_t siginfo;
int status;
int ret = -1;
again:
if (ptrace(PTRACE_SETREGS, pid, NULL, regs)) {
pr_perror("Can't set registers (pid: %d)", pid);
goto err;
}
/*
* Most ideas are taken from Tejun Heo's parasite thread
* https://code.google.com/p/ptrace-parasite/
*/
if (ptrace(PTRACE_CONT, pid, NULL, NULL)) {
pr_perror("Can't continue (pid: %d)", pid);
goto err;
}
if (wait4(pid, &status, __WALL, NULL) != pid) {
pr_perror("Waited pid mismatch (pid: %d)", pid);
goto err;
}
if (!WIFSTOPPED(status)) {
pr_err("Task is still running (pid: %d)\n", pid);
goto err;
}
if (ptrace(PTRACE_GETSIGINFO, pid, NULL, &siginfo)) {
pr_perror("Can't get siginfo (pid: %d)", pid);
goto err;
}
if (ptrace(PTRACE_GETREGS, pid, NULL, regs)) {
pr_perror("Can't obtain registers (pid: %d)", pid);
goto err;
}
if (WSTOPSIG(status) != SIGTRAP || siginfo.si_code != ARCH_SI_TRAP) {
retry_signal:
pr_debug("** delivering signal %d si_code=%d\n",
siginfo.si_signo, siginfo.si_code);
if (ctl->signals_blocked) {
pr_err("Unexpected %d task interruption, aborting\n", pid);
goto err;
}
/* FIXME: jerr(siginfo.si_code > 0, err_restore); */
/*
* This requires some explanation. If a signal from original
* program delivered while we're trying to execute our
* injected blob -- we need to setup original registers back
* so the kernel would make sigframe for us and update the
* former registers.
*
* Then we should swap registers back to our modified copy
* and retry.
*/
if (ptrace(PTRACE_SETREGS, pid, NULL, &ctl->regs_orig)) {
pr_perror("Can't set registers (pid: %d)", pid);
goto err;
}
if (ptrace(PTRACE_INTERRUPT, pid, NULL, NULL)) {
pr_perror("Can't interrupt (pid: %d)", pid);
goto err;
}
if (ptrace(PTRACE_CONT, pid, NULL, (void *)(unsigned long)siginfo.si_signo)) {
pr_perror("Can't continue (pid: %d)", pid);
goto err;
}
if (wait4(pid, &status, __WALL, NULL) != pid) {
pr_perror("Waited pid mismatch (pid: %d)", pid);
goto err;
}
if (!WIFSTOPPED(status)) {
pr_err("Task is still running (pid: %d)\n", pid);
goto err;
}
if (ptrace(PTRACE_GETSIGINFO, pid, NULL, &siginfo)) {
pr_perror("Can't get siginfo (pid: %d)", pid);
goto err;
}
if (SI_EVENT(siginfo.si_code) != PTRACE_EVENT_STOP)
goto retry_signal;
/*
* Signal is delivered, so we should update
* original registers.
*/
{
user_regs_struct_t r;
if (ptrace(PTRACE_GETREGS, pid, NULL, &r)) {
pr_perror("Can't obtain registers (pid: %d)", pid);
goto err;
}
ctl->regs_orig = r;
}
goto again;
}
/*
* We've reached this point if int3 is triggered inside our
* parasite code. So we're done.
*/
ret = 0;
err:
return ret;
}
void *parasite_args_s(struct parasite_ctl *ctl, int args_size)
{
BUG_ON(args_size > ctl->args_size);
return ctl->addr_args;
}
#define parasite_args(ctl, type) ({ \
BUILD_BUG_ON(sizeof(type) > PARASITE_ARG_SIZE_MIN);\
ctl->addr_args; \
})
static int parasite_execute_by_pid(unsigned int cmd, struct parasite_ctl *ctl, pid_t pid)
{
int ret;
user_regs_struct_t regs_orig, regs;
if (ctl->pid.real == pid)
regs = ctl->regs_orig;
else {
if (ptrace(PTRACE_GETREGS, pid, NULL, ®s_orig)) {
pr_perror("Can't obtain registers (pid: %d)", pid);
return -1;
}
regs = regs_orig;
}
*ctl->addr_cmd = cmd;
parasite_setup_regs(ctl->parasite_ip, ®s);
ret = __parasite_execute(ctl, pid, ®s);
if (ret == 0)
ret = (int)REG_RES(regs);
if (ret)
pr_err("Parasite exited with %d\n", ret);
if (ctl->pid.real != pid)
if (ptrace(PTRACE_SETREGS, pid, NULL, ®s_orig)) {
pr_perror("Can't restore registers (pid: %d)", pid);
return -1;
}
return ret;
}
int parasite_execute(unsigned int cmd, struct parasite_ctl *ctl)
{
return parasite_execute_by_pid(cmd, ctl, ctl->pid.real);
}
static int munmap_seized(struct parasite_ctl *ctl, void *addr, size_t length)
{
unsigned long x;
return syscall_seized(ctl, __NR_munmap, &x,
(unsigned long)addr, length, 0, 0, 0, 0);
}
static int gen_parasite_saddr(struct sockaddr_un *saddr, int key)
{
int sun_len;
saddr->sun_family = AF_UNIX;
snprintf(saddr->sun_path, UNIX_PATH_MAX,
"X/crtools-pr-%d", key);
sun_len = SUN_LEN(saddr);
*saddr->sun_path = '\0';
return sun_len;
}
int parasite_send_fd(struct parasite_ctl *ctl, int fd)
{
if (send_fd(ctl->tsock, NULL, 0, fd) < 0) {
pr_perror("Can't send file descriptor");
return -1;
}
return 0;
}
static int parasite_set_logfd(struct parasite_ctl *ctl, pid_t pid)
{
int ret;
struct parasite_log_args *a;
ret = parasite_send_fd(ctl, log_get_fd());
if (ret)
return ret;
a = parasite_args(ctl, struct parasite_log_args);
a->log_level = log_get_loglevel();
ret = parasite_execute(PARASITE_CMD_CFG_LOG, ctl);
if (ret < 0)
return ret;
return 0;
}
static int parasite_init(struct parasite_ctl *ctl, pid_t pid, int nr_threads)
{
struct parasite_init_args *args;
static int sock = -1;
args = parasite_args(ctl, struct parasite_init_args);
pr_info("Putting tsock into pid %d\n", pid);
args->h_addr_len = gen_parasite_saddr(&args->h_addr, getpid());
args->p_addr_len = gen_parasite_saddr(&args->p_addr, pid);
args->nr_threads = nr_threads;
if (sock == -1) {
int rst = -1;
if (current_ns_mask & CLONE_NEWNET) {
pr_info("Switching to %d's net for tsock creation\n", pid);
if (switch_ns(pid, &net_ns_desc, &rst))
return -1;
}
sock = socket(PF_UNIX, SOCK_DGRAM, 0);
if (sock < 0)
pr_perror("Can't create socket");
if (rst > 0 && restore_ns(rst, &net_ns_desc) < 0)
return -1;
if (sock < 0)
return -1;
if (bind(sock, (struct sockaddr *)&args->h_addr, args->h_addr_len) < 0) {
pr_perror("Can't bind socket");
goto err;
}
} else {
struct sockaddr addr = { .sa_family = AF_UNSPEC, };
/*
* When the peer of a dgram socket dies the original socket
* remains in connected state, thus denying any connections
* from "other" sources. Unconnect the socket by hands thus
* allowing for parasite to connect back.
*/
if (connect(sock, &addr, sizeof(addr)) < 0) {
pr_perror("Can't unconnect");
goto err;
}
}
if (parasite_execute(PARASITE_CMD_INIT, ctl) < 0) {
pr_err("Can't init parasite\n");
goto err;
}
if (connect(sock, (struct sockaddr *)&args->p_addr, args->p_addr_len) < 0) {
pr_perror("Can't connect a transport socket");
goto err;
}
ctl->tsock = sock;
return 0;
err:
close_safe(&sock);
return -1;
}
int parasite_dump_thread_seized(struct parasite_ctl *ctl, struct pid *tid,
CoreEntry *core)
{
struct parasite_dump_thread *args;
int ret;
args = parasite_args(ctl, struct parasite_dump_thread);
ret = parasite_execute_by_pid(PARASITE_CMD_DUMP_THREAD, ctl, tid->real);
memcpy(&core->thread_core->blk_sigset, &args->blocked, sizeof(args->blocked));
CORE_THREAD_ARCH_INFO(core)->clear_tid_addr = encode_pointer(args->tid_addr);
tid->virt = args->tid;
core_put_tls(core, args->tls);
return ret;
}
int parasite_dump_sigacts_seized(struct parasite_ctl *ctl, struct cr_fdset *cr_fdset)
{
struct parasite_dump_sa_args *args;
int ret, sig, fd;
SaEntry se = SA_ENTRY__INIT;
args = parasite_args(ctl, struct parasite_dump_sa_args);
ret = parasite_execute(PARASITE_CMD_DUMP_SIGACTS, ctl);
if (ret < 0)
return ret;
fd = fdset_fd(cr_fdset, CR_FD_SIGACT);
for (sig = 1; sig <= SIGMAX; sig++) {
int i = sig - 1;
if (sig == SIGSTOP || sig == SIGKILL)
continue;
ASSIGN_TYPED(se.sigaction, encode_pointer(args->sas[i].rt_sa_handler));
ASSIGN_TYPED(se.flags, args->sas[i].rt_sa_flags);
ASSIGN_TYPED(se.restorer, encode_pointer(args->sas[i].rt_sa_restorer));
ASSIGN_TYPED(se.mask, args->sas[i].rt_sa_mask.sig[0]);
if (pb_write_one(fd, &se, PB_SIGACT) < 0)
return -1;
}
return 0;
}
static int dump_one_timer(struct itimerval *v, int fd)
{
ItimerEntry ie = ITIMER_ENTRY__INIT;
ie.isec = v->it_interval.tv_sec;
ie.iusec = v->it_interval.tv_usec;
ie.vsec = v->it_value.tv_sec;
ie.vusec = v->it_value.tv_usec;
return pb_write_one(fd, &ie, PB_ITIMERS);
}
int parasite_dump_itimers_seized(struct parasite_ctl *ctl, struct cr_fdset *cr_fdset)
{
struct parasite_dump_itimers_args *args;
int ret, fd;
args = parasite_args(ctl, struct parasite_dump_itimers_args);
ret = parasite_execute(PARASITE_CMD_DUMP_ITIMERS, ctl);
if (ret < 0)
return ret;
fd = fdset_fd(cr_fdset, CR_FD_ITIMERS);
ret = dump_one_timer(&args->real, fd);
if (!ret)
ret = dump_one_timer(&args->virt, fd);
if (!ret)
ret = dump_one_timer(&args->prof, fd);
return ret;
}
int parasite_dump_misc_seized(struct parasite_ctl *ctl, struct parasite_dump_misc *misc)
{
struct parasite_dump_misc *ma;
ma = parasite_args(ctl, struct parasite_dump_misc);
if (parasite_execute(PARASITE_CMD_DUMP_MISC, ctl) < 0)
return -1;
*misc = *ma;
return 0;
}
struct parasite_tty_args *parasite_dump_tty(struct parasite_ctl *ctl, int fd)
{
struct parasite_tty_args *p;
p = parasite_args(ctl, struct parasite_tty_args);
p->fd = fd;
if (parasite_execute(PARASITE_CMD_DUMP_TTY, ctl) < 0)
return NULL;
return p;
}
int parasite_dump_creds(struct parasite_ctl *ctl, CredsEntry *ce)
{
struct parasite_dump_creds *pc;
pc = parasite_args(ctl, struct parasite_dump_creds);
if (parasite_execute(PARASITE_CMD_DUMP_CREDS, ctl) < 0)
return -1;
ce->secbits = pc->secbits;
ce->n_groups = pc->ngroups;
/*
* Achtung! We leak the parasite args pointer to the caller.
* It's not safe in general, but in our case is OK, since the
* latter doesn't go to parasite before using the data in it.
*/
BUILD_BUG_ON(sizeof(ce->groups[0]) != sizeof(pc->groups[0]));
ce->groups = pc->groups;
return 0;
}
int parasite_drain_fds_seized(struct parasite_ctl *ctl,
struct parasite_drain_fd *dfds, int *lfds, struct fd_opts *opts)
{
int ret = -1, size;
struct parasite_drain_fd *args;
size = drain_fds_size(dfds);
args = parasite_args_s(ctl, size);
memcpy(args, dfds, size);
ret = parasite_execute(PARASITE_CMD_DRAIN_FDS, ctl);
if (ret) {
pr_err("Parasite failed to drain descriptors\n");
goto err;
}
ret = recv_fds(ctl->tsock, lfds, dfds->nr_fds, opts);
if (ret) {
pr_err("Can't retrieve FDs from socket\n");
goto err;
}
err:
return ret;
}
int parasite_get_proc_fd_seized(struct parasite_ctl *ctl)
{
int ret = -1, fd;
ret = parasite_execute(PARASITE_CMD_GET_PROC_FD, ctl);
if (ret) {
pr_err("Parasite failed to get proc fd\n");
return ret;
}
fd = recv_fd(ctl->tsock);
if (fd < 0) {
pr_err("Can't retrieve FD from socket\n");
return fd;
}
return fd;
}
int parasite_init_threads_seized(struct parasite_ctl *ctl, struct pstree_item *item)
{
int ret = 0, i;
for (i = 0; i < item->nr_threads; i++) {
if (item->pid.real == item->threads[i].real)
continue;
ret = parasite_execute_by_pid(PARASITE_CMD_INIT_THREAD, ctl,
item->threads[i].real);
if (ret) {
pr_err("Can't init thread in parasite %d\n",
item->threads[i].real);
break;
}
}
return ret;
}
int parasite_fini_threads_seized(struct parasite_ctl *ctl, struct pstree_item *item)
{
int ret = 0, i;
for (i = 0; i < item->nr_threads; i++) {
if (item->pid.real == item->threads[i].real)
continue;
ret = parasite_execute_by_pid(PARASITE_CMD_FINI_THREAD, ctl,
item->threads[i].real);
/*
* Note the thread's fini() can be called even when not
* all threads were init()'ed, say we're rolling back from
* error happened while we were init()'ing some thread, thus
* -ENOENT will be returned but we should continie for the
* rest of threads set.
*
* Strictly speaking we always init() threads in sequence thus
* we could simply break the loop once first -ENOENT returned
* but I prefer to be on a safe side even if some future changes
* would change the code logic.
*/
if (ret && ret != -ENOENT) {
pr_err("Can't fini thread in parasite %d\n",
item->threads[i].real);
break;
}
}
return ret;
}
int parasite_cure_remote(struct parasite_ctl *ctl, struct pstree_item *item)
{
int ret = 0;
ctl->tsock = -1;
if (ctl->parasite_ip) {
ctl->signals_blocked = 0;
parasite_fini_threads_seized(ctl, item);
parasite_execute(PARASITE_CMD_FINI, ctl);
}
if (ctl->remote_map) {
if (munmap_seized(ctl, (void *)ctl->remote_map, ctl->map_length)) {
pr_err("munmap_seized failed (pid: %d)\n", ctl->pid.real);
ret = -1;
}
}
if (ptrace_poke_area(ctl->pid.real, (void *)ctl->code_orig,
(void *)ctl->syscall_ip, sizeof(ctl->code_orig))) {
pr_err("Can't restore syscall blob (pid: %d)\n", ctl->pid.real);
ret = -1;
}
if (ptrace(PTRACE_SETREGS, ctl->pid.real, NULL, &ctl->regs_orig)) {
pr_err("Can't restore registers (pid: %d)\n", ctl->pid.real);
ret = -1;
}
return ret;
}
int parasite_cure_local(struct parasite_ctl *ctl)
{
int ret = 0;
if (ctl->local_map) {
if (munmap(ctl->local_map, ctl->map_length)) {
pr_err("munmap failed (pid: %d)\n", ctl->pid.real);
ret = -1;
}
}
free(ctl);
return ret;
}
int parasite_cure_seized(struct parasite_ctl *ctl, struct pstree_item *item)
{
int ret;
ret = parasite_cure_remote(ctl, item);
if (!ret)
ret = parasite_cure_local(ctl);
return ret;
}
struct parasite_ctl *parasite_prep_ctl(pid_t pid, struct vm_area_list *vma_area_list)
{
struct parasite_ctl *ctl = NULL;
struct vma_area *vma_area;
if (!arch_can_dump_task(pid))
goto err;
/*
* Control block early setup.
*/
ctl = xzalloc(sizeof(*ctl));
if (!ctl) {
pr_err("Parasite control block allocation failed (pid: %d)\n", pid);
goto err;
}
ctl->tsock = -1;
if (ptrace(PTRACE_GETREGS, pid, NULL, &ctl->regs_orig)) {
pr_err("Can't obtain registers (pid: %d)\n", pid);
goto err;
}
vma_area = get_vma_by_ip(&vma_area_list->h, REG_IP(ctl->regs_orig));
if (!vma_area) {
pr_err("No suitable VMA found to run parasite "
"bootstrap code (pid: %d)\n", pid);
goto err;
}
ctl->pid.real = pid;
ctl->pid.virt = 0;
ctl->syscall_ip = vma_area->vma.start;
/*
* Inject syscall instruction and remember original code,
* we will need it to restore original program content.
*/
memcpy(ctl->code_orig, code_syscall, sizeof(ctl->code_orig));
if (ptrace_swap_area(pid, (void *)ctl->syscall_ip,
(void *)ctl->code_orig, sizeof(ctl->code_orig))) {
pr_err("Can't inject syscall blob (pid: %d)\n", pid);
goto err;
}
return ctl;
err:
xfree(ctl);
return NULL;
}
int parasite_map_exchange(struct parasite_ctl *ctl, unsigned long size)
{
int fd;
ctl->remote_map = mmap_seized(ctl, NULL, size,
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_ANONYMOUS | MAP_SHARED, -1, 0);
if (!ctl->remote_map) {
pr_err("Can't allocate memory for parasite blob (pid: %d)\n", ctl->pid.real);
return -1;
}
ctl->map_length = round_up(size, PAGE_SIZE);
fd = open_proc_rw(ctl->pid.real, "map_files/%p-%p",
ctl->remote_map, ctl->remote_map + ctl->map_length);
if (fd < 0)
return -1;
ctl->local_map = mmap(NULL, size, PROT_READ | PROT_WRITE,
MAP_SHARED | MAP_FILE, fd, 0);
close(fd);
if (ctl->local_map == MAP_FAILED) {
ctl->local_map = NULL;
pr_perror("Can't map remote parasite map");
return -1;
}
return 0;
}
static unsigned long parasite_args_size(struct vm_area_list *vmas, struct parasite_drain_fd *dfds)
{
unsigned long size = PARASITE_ARG_SIZE_MIN;
if (dfds)
size = max(size, (unsigned long)drain_fds_size(dfds));
size = max(size, (unsigned long)dump_pages_args_size(vmas));
return size;
}
struct parasite_ctl *parasite_infect_seized(pid_t pid, struct pstree_item *item,
struct vm_area_list *vma_area_list, struct parasite_drain_fd *dfds)
{
int ret;
struct parasite_ctl *ctl;
ctl = parasite_prep_ctl(pid, vma_area_list);
if (!ctl)
return NULL;
/*
* Inject a parasite engine. Ie allocate memory inside alien
* space and copy engine code there. Then re-map the engine
* locally, so we will get an easy way to access engine memory
* without using ptrace at all.
*/
ctl->args_size = parasite_args_size(vma_area_list, dfds);
ret = parasite_map_exchange(ctl, parasite_size + ctl->args_size);
if (ret)
goto err_restore;
pr_info("Putting parasite blob into %p->%p\n", ctl->local_map, ctl->remote_map);
memcpy(ctl->local_map, parasite_blob, sizeof(parasite_blob));
/* Setup the rest of a control block */
ctl->parasite_ip = (unsigned long)parasite_sym(ctl->remote_map, __export_parasite_head_start);
ctl->addr_cmd = parasite_sym(ctl->local_map, __export_parasite_cmd);
ctl->addr_args = parasite_sym(ctl->local_map, __export_parasite_args);
ret = parasite_init(ctl, pid, item->nr_threads);
if (ret) {
pr_err("%d: Can't create a transport socket\n", pid);
goto err_restore;
}
ctl->signals_blocked = 1;
ret = parasite_set_logfd(ctl, pid);
if (ret) {
pr_err("%d: Can't set a logging descriptor\n", pid);
goto err_restore;
}
ret = parasite_init_threads_seized(ctl, item);
if (ret)
goto err_restore;
return ctl;
err_restore:
parasite_cure_seized(ctl, item);
return NULL;
}