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criu: move sigact dump/restore code into sigact.c
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Seperate sigact dump/restore code from cr-restore.c and parasite-syscall.c into sigact.c

Signed-off-by: Arnav Bhatt <[email protected]>
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@arnavbhatt288 @avagin
arnavbhatt288 authored and avagin committed May 25, 2024
1 parent 8631228 commit 1a848fe
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Showing 7 changed files with 336 additions and 315 deletions.
1 change: 1 addition & 0 deletions criu/Makefile.crtools
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Expand Up @@ -93,6 +93,7 @@ obj-y += pie-util-vdso.o
obj-y += vdso.o
obj-y += timens.o
obj-y += timer.o
obj-y += sigact.o
obj-$(CONFIG_HAS_LIBBPF) += bpfmap.o
obj-$(CONFIG_COMPAT) += pie-util-vdso-elf32.o
CFLAGS_pie-util-vdso-elf32.o += -DCONFIG_VDSO_32
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1 change: 1 addition & 0 deletions criu/cr-dump.c
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Expand Up @@ -87,6 +87,7 @@
#include "apparmor.h"
#include "asm/dump.h"
#include "timer.h"
#include "sigact.h"

/*
* Architectures can overwrite this function to restore register sets that
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263 changes: 1 addition & 262 deletions criu/cr-restore.c
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Expand Up @@ -99,6 +99,7 @@

#include "cr-errno.h"
#include "timer.h"
#include "sigact.h"

#ifndef arch_export_restore_thread
#define arch_export_restore_thread __export_restore_thread
Expand Down Expand Up @@ -407,268 +408,6 @@ static int populate_pid_proc(void)
return 0;
}

static rt_sigaction_t sigchld_act;
/*
* If parent's sigaction has blocked SIGKILL (which is non-sense),
* this parent action is non-valid and shouldn't be inherited.
* Used to mark parent_act* no more valid.
*/
static rt_sigaction_t parent_act[SIGMAX];
#ifdef CONFIG_COMPAT
static rt_sigaction_t_compat parent_act_compat[SIGMAX];
#endif

static bool sa_inherited(int sig, rt_sigaction_t *sa)
{
rt_sigaction_t *pa;
int i;

if (current == root_item)
return false; /* XXX -- inherit from CRIU? */

pa = &parent_act[sig];

/* Omitting non-valid sigaction */
if (pa->rt_sa_mask.sig[0] & (1 << SIGKILL))
return false;

for (i = 0; i < _KNSIG_WORDS; i++)
if (pa->rt_sa_mask.sig[i] != sa->rt_sa_mask.sig[i])
return false;

return pa->rt_sa_handler == sa->rt_sa_handler && pa->rt_sa_flags == sa->rt_sa_flags &&
pa->rt_sa_restorer == sa->rt_sa_restorer;
}

static int restore_native_sigaction(int sig, SaEntry *e)
{
rt_sigaction_t act;
int ret;

ASSIGN_TYPED(act.rt_sa_handler, decode_pointer(e->sigaction));
ASSIGN_TYPED(act.rt_sa_flags, e->flags);
ASSIGN_TYPED(act.rt_sa_restorer, decode_pointer(e->restorer));
#ifdef CONFIG_MIPS
e->has_mask_extended = 1;
BUILD_BUG_ON(sizeof(e->mask) * 2 != sizeof(act.rt_sa_mask.sig));

memcpy(&(act.rt_sa_mask.sig[0]), &e->mask, sizeof(act.rt_sa_mask.sig[0]));
memcpy(&(act.rt_sa_mask.sig[1]), &e->mask_extended, sizeof(act.rt_sa_mask.sig[1]));
#else
BUILD_BUG_ON(sizeof(e->mask) != sizeof(act.rt_sa_mask.sig));
memcpy(act.rt_sa_mask.sig, &e->mask, sizeof(act.rt_sa_mask.sig));
#endif
if (sig == SIGCHLD) {
sigchld_act = act;
return 0;
}

if (sa_inherited(sig - 1, &act))
return 1;

/*
* A pure syscall is used, because glibc
* sigaction overwrites se_restorer.
*/
ret = syscall(SYS_rt_sigaction, sig, &act, NULL, sizeof(k_rtsigset_t));
if (ret < 0) {
pr_perror("Can't restore sigaction");
return ret;
}

parent_act[sig - 1] = act;
/* Mark SIGKILL blocked which makes compat sigaction non-valid */
#ifdef CONFIG_COMPAT
parent_act_compat[sig - 1].rt_sa_mask.sig[0] |= 1 << SIGKILL;
#endif

return 1;
}

static void *stack32;

#ifdef CONFIG_COMPAT
static bool sa_compat_inherited(int sig, rt_sigaction_t_compat *sa)
{
rt_sigaction_t_compat *pa;
int i;

if (current == root_item)
return false;

pa = &parent_act_compat[sig];

/* Omitting non-valid sigaction */
if (pa->rt_sa_mask.sig[0] & (1 << SIGKILL))
return false;

for (i = 0; i < _KNSIG_WORDS; i++)
if (pa->rt_sa_mask.sig[i] != sa->rt_sa_mask.sig[i])
return false;

return pa->rt_sa_handler == sa->rt_sa_handler && pa->rt_sa_flags == sa->rt_sa_flags &&
pa->rt_sa_restorer == sa->rt_sa_restorer;
}

static int restore_compat_sigaction(int sig, SaEntry *e)
{
rt_sigaction_t_compat act;
int ret;

ASSIGN_TYPED(act.rt_sa_handler, (u32)e->sigaction);
ASSIGN_TYPED(act.rt_sa_flags, e->flags);
ASSIGN_TYPED(act.rt_sa_restorer, (u32)e->restorer);
BUILD_BUG_ON(sizeof(e->mask) != sizeof(act.rt_sa_mask.sig));
memcpy(act.rt_sa_mask.sig, &e->mask, sizeof(act.rt_sa_mask.sig));

if (sig == SIGCHLD) {
memcpy(&sigchld_act, &act, sizeof(rt_sigaction_t_compat));
return 0;
}

if (sa_compat_inherited(sig - 1, &act))
return 1;

if (!stack32) {
stack32 = alloc_compat_syscall_stack();
if (!stack32)
return -1;
}

ret = arch_compat_rt_sigaction(stack32, sig, &act);
if (ret < 0) {
pr_err("Can't restore compat sigaction: %d\n", ret);
return ret;
}

parent_act_compat[sig - 1] = act;
/* Mark SIGKILL blocked which makes native sigaction non-valid */
parent_act[sig - 1].rt_sa_mask.sig[0] |= 1 << SIGKILL;

return 1;
}
#else
static int restore_compat_sigaction(int sig, SaEntry *e)
{
return -1;
}
#endif

static int prepare_sigactions_from_core(TaskCoreEntry *tc)
{
int sig, i;

if (tc->n_sigactions != SIGMAX - 2) {
pr_err("Bad number of sigactions in the image (%d, want %d)\n", (int)tc->n_sigactions, SIGMAX - 2);
return -1;
}

pr_info("Restore on-core sigactions for %d\n", vpid(current));

for (sig = 1, i = 0; sig <= SIGMAX; sig++) {
int ret;
SaEntry *e;
bool sigaction_is_compat;

if (sig == SIGKILL || sig == SIGSTOP)
continue;

e = tc->sigactions[i++];
sigaction_is_compat = e->has_compat_sigaction && e->compat_sigaction;
if (sigaction_is_compat)
ret = restore_compat_sigaction(sig, e);
else
ret = restore_native_sigaction(sig, e);

if (ret < 0)
return ret;
}

return 0;
}

/* Returns number of restored signals, -1 or negative errno on fail */
static int restore_one_sigaction(int sig, struct cr_img *img, int pid)
{
bool sigaction_is_compat;
SaEntry *e;
int ret = 0;

BUG_ON(sig == SIGKILL || sig == SIGSTOP);

ret = pb_read_one_eof(img, &e, PB_SIGACT);
if (ret == 0) {
if (sig != SIGMAX_OLD + 1) { /* backward compatibility */
pr_err("Unexpected EOF %d\n", sig);
return -1;
}
pr_warn("This format of sigacts-%d.img is deprecated\n", pid);
return -1;
}
if (ret < 0)
return ret;

sigaction_is_compat = e->has_compat_sigaction && e->compat_sigaction;
if (sigaction_is_compat)
ret = restore_compat_sigaction(sig, e);
else
ret = restore_native_sigaction(sig, e);

sa_entry__free_unpacked(e, NULL);

return ret;
}

static int prepare_sigactions_from_image(void)
{
int pid = vpid(current);
struct cr_img *img;
int sig, rst = 0;
int ret = 0;

pr_info("Restore sigacts for %d\n", pid);

img = open_image(CR_FD_SIGACT, O_RSTR, pid);
if (!img)
return -1;

for (sig = 1; sig <= SIGMAX; sig++) {
if (sig == SIGKILL || sig == SIGSTOP)
continue;

ret = restore_one_sigaction(sig, img, pid);
if (ret < 0)
break;
if (ret)
rst++;
}

pr_info("Restored %d/%d sigacts\n", rst, SIGMAX - 3 /* KILL, STOP and CHLD */);

close_image(img);
return ret;
}

static int prepare_sigactions(CoreEntry *core)
{
int ret;

if (!task_alive(current))
return 0;

if (core->tc->n_sigactions != 0)
ret = prepare_sigactions_from_core(core->tc);
else
ret = prepare_sigactions_from_image();

if (stack32) {
free_compat_syscall_stack(stack32);
stack32 = NULL;
}

return ret;
}

static int __collect_child_pids(struct pstree_item *p, int state, unsigned int *n)
{
struct pstree_item *pi;
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2 changes: 0 additions & 2 deletions criu/include/parasite-syscall.h
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Expand Up @@ -21,8 +21,6 @@ struct rt_sigframe;
struct parasite_ctl;
struct parasite_thread_ctl;

extern int parasite_dump_sigacts_seized(struct parasite_ctl *ctl, struct pstree_item *);

extern int parasite_dump_misc_seized(struct parasite_ctl *ctl, struct parasite_dump_misc *misc);
extern int parasite_dump_creds(struct parasite_ctl *ctl, CredsEntry *ce);
extern int parasite_dump_thread_leader_seized(struct parasite_ctl *ctl, int pid, CoreEntry *core);
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14 changes: 14 additions & 0 deletions criu/include/sigact.h
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@@ -0,0 +1,14 @@
#ifndef __CR_SIGACT_H__
#define __CR_SIGACT_H__

#include "images/core.pb-c.h"

extern rt_sigaction_t sigchld_act;

struct parasite_ctl;
struct pstree_item;

extern int prepare_sigactions(CoreEntry *core);
extern int parasite_dump_sigacts_seized(struct parasite_ctl *ctl, struct pstree_item *);

#endif
51 changes: 0 additions & 51 deletions criu/parasite-syscall.c
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Expand Up @@ -9,7 +9,6 @@
#include "common/compiler.h"
#include "types.h"
#include "protobuf.h"
#include "images/sa.pb-c.h"
#include "images/timer.pb-c.h"
#include "images/creds.pb-c.h"
#include "images/core.pb-c.h"
Expand Down Expand Up @@ -228,56 +227,6 @@ int parasite_dump_thread_seized(struct parasite_thread_ctl *tctl, struct parasit
return dump_thread_core(pid, core, args);
}

int parasite_dump_sigacts_seized(struct parasite_ctl *ctl, struct pstree_item *item)
{
TaskCoreEntry *tc = item->core[0]->tc;
struct parasite_dump_sa_args *args;
int ret, sig;
SaEntry *sa, **psa;

args = compel_parasite_args(ctl, struct parasite_dump_sa_args);

ret = compel_rpc_call_sync(PARASITE_CMD_DUMP_SIGACTS, ctl);
if (ret < 0)
return ret;

psa = xmalloc((SIGMAX - 2) * (sizeof(SaEntry *) + sizeof(SaEntry)));
if (!psa)
return -1;

sa = (SaEntry *)(psa + SIGMAX - 2);

tc->n_sigactions = SIGMAX - 2;
tc->sigactions = psa;

for (sig = 1; sig <= SIGMAX; sig++) {
int i = sig - 1;

if (sig == SIGSTOP || sig == SIGKILL)
continue;

sa_entry__init(sa);
ASSIGN_TYPED(sa->sigaction, encode_pointer(args->sas[i].rt_sa_handler));
ASSIGN_TYPED(sa->flags, args->sas[i].rt_sa_flags);
ASSIGN_TYPED(sa->restorer, encode_pointer(args->sas[i].rt_sa_restorer));
#ifdef CONFIG_MIPS
sa->has_mask_extended = 1;
BUILD_BUG_ON(sizeof(sa->mask) * 2 != sizeof(args->sas[0].rt_sa_mask.sig));
memcpy(&sa->mask, &(args->sas[i].rt_sa_mask.sig[0]), sizeof(sa->mask));
memcpy(&sa->mask_extended, &(args->sas[i].rt_sa_mask.sig[1]), sizeof(sa->mask));
#else
BUILD_BUG_ON(sizeof(sa->mask) != sizeof(args->sas[0].rt_sa_mask.sig));
memcpy(&sa->mask, args->sas[i].rt_sa_mask.sig, sizeof(sa->mask));
#endif
sa->has_compat_sigaction = true;
sa->compat_sigaction = !compel_mode_native(ctl);

*(psa++) = sa++;
}

return 0;
}

int parasite_dump_misc_seized(struct parasite_ctl *ctl, struct parasite_dump_misc *misc)
{
struct parasite_dump_misc *ma;
Expand Down
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