#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <elf.h>
#include <fcntl.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/wait.h>

#include "types.h"
#include "parasite-syscall.h"
#include "parasite.h"
#include "common/compiler.h"
#include "kerndat.h"
#include "vdso.h"
#include "util.h"
#include "criu-log.h"
#include "mem.h"
#include "vma.h"
#include <compel/compel.h>
#include <compel/plugins/std/syscall.h>

#ifdef LOG_PREFIX
# undef LOG_PREFIX
#endif
#define LOG_PREFIX "vdso: "

u64 vdso_pfn = VDSO_BAD_PFN;
struct vdso_maps vdso_maps		= VDSO_MAPS_INIT;
struct vdso_maps vdso_maps_compat	= VDSO_MAPS_INIT;

/*
 * Starting with 3.16 the [vdso]/[vvar] marks are reported correctly
 * even when they are remapped into a new place, but only since that
 * particular version of the kernel!
 * On previous kernels we need to check if vma is vdso by some means:
 * - if pagemap is present, by pfn
 * - by parsing ELF and filling vdso symtable otherwise
 */
enum vdso_check_t {
	/* from slowest to fastest */
	VDSO_CHECK_SYMS = 0,
	VDSO_CHECK_PFN,
	VDSO_NO_CHECK,
};

static enum vdso_check_t get_vdso_check_type(struct parasite_ctl *ctl)
{
	/*
	 * ia32 C/R depends on mremap() for vdso patches (v4.8),
	 * so we can omit any check and be sure that "[vdso]"
	 * hint stays in /proc/../maps file and is correct.
	 */
	if (!compel_mode_native(ctl)) {
		pr_info("Don't check vdso for compat task\n");
		return VDSO_NO_CHECK;
	}

	if (kdat.vdso_hint_reliable) {
		pr_info("vDSO hint is reliable - omit checking\n");
		return VDSO_NO_CHECK;
	}

	if (kdat.pmap == PM_FULL) {
		pr_info("Check vdso by pfn from pagemap\n");
		return VDSO_CHECK_PFN;
	}

	pr_info("Pagemap is unavailable, check vdso by filling symtable\n");
	return VDSO_CHECK_SYMS;
}

static int check_vdso_by_pfn(int pagemap_fd, struct vma_area *vma,
			bool *has_vdso_pfn)
{
	u64 pfn = VDSO_BAD_PFN;

	if (vaddr_to_pfn(pagemap_fd, vma->e->start, &pfn))
		return -1;

	if (!pfn) {
		pr_err("Unexpected page frame number 0\n");
		return -1;
	}

	if ((pfn == vdso_pfn && pfn != VDSO_BAD_PFN))
		*has_vdso_pfn = true;
	else
		*has_vdso_pfn = false;

	return 0;
}

static bool not_vvar_or_vdso(struct vma_area *vma)
{
	if (!vma_area_is(vma, VMA_AREA_REGULAR))
		return true;

	if (vma_area_is(vma, VMA_FILE_SHARED))
		return true;

	if (vma_area_is(vma, VMA_FILE_PRIVATE))
		return true;

	if (vma->e->start > kdat.task_size)
		return true;

	if (vma->e->flags & MAP_GROWSDOWN)
		return true;

	BUILD_BUG_ON(!(VDSO_PROT & VVAR_PROT));
	if ((vma->e->prot & VVAR_PROT) != VVAR_PROT)
		return true;

	return false;
}

/* Contains addresses from vdso mark */
struct vdso_quarter {
	unsigned long orig_vdso;
	unsigned long orig_vvar;
	unsigned long rt_vdso;
	unsigned long rt_vvar;
};

static void drop_rt_vdso(struct vm_area_list *vma_area_list,
	struct vdso_quarter *addr, struct vma_area *rt_vdso_marked)
{
	struct vma_area *rt_vvar_marked = NULL;
	struct vma_area *vma;

	if (!rt_vdso_marked)
		return;

	/*
	 * There is marked vdso, it means such vdso is autogenerated
	 * and must be dropped from vma list.
	 */
	pr_debug("vdso: Found marked at %lx (orig vDSO at %lx VVAR at %lx)\n",
		(long)rt_vdso_marked->e->start, addr->orig_vdso, addr->orig_vvar);

	/*
	 * Don't forget to restore the proxy vdso/vvar status, since
	 * they're unknown to the kernel.
	 * Also BTW search for rt-vvar to remove it later.
	 */
	list_for_each_entry(vma, &vma_area_list->h, list) {
		if (vma->e->start == addr->orig_vdso) {
			vma->e->status |= VMA_AREA_REGULAR | VMA_AREA_VDSO;
			pr_debug("vdso: Restore orig vDSO status at %lx\n",
					(long)vma->e->start);
		} else if (vma->e->start == addr->orig_vvar) {
			vma->e->status |= VMA_AREA_REGULAR | VMA_AREA_VVAR;
			pr_debug("vdso: Restore orig VVAR status at %lx\n",
					(long)vma->e->start);
		} else if (addr->rt_vvar != VVAR_BAD_ADDR &&
				addr->rt_vvar == vma->e->start) {
			BUG_ON(rt_vvar_marked);
			if (not_vvar_or_vdso(vma)) {
				pr_warn("Mark in rt-vdso points to vma, that doesn't look like vvar - skipping unmap\n");
				continue;
			}
			rt_vvar_marked = vma;
		}
	}

	pr_debug("vdso: Dropping marked vdso at %lx\n",
			(long)rt_vdso_marked->e->start);
	list_del(&rt_vdso_marked->list);
	xfree(rt_vdso_marked);
	vma_area_list->nr--;

	if (rt_vvar_marked) {
		pr_debug("vdso: Dropping marked vvar at %lx\n",
				(long)rt_vvar_marked->e->start);
		list_del(&rt_vvar_marked->list);
		xfree(rt_vvar_marked);
		vma_area_list->nr--;
	}
}

/*
 * I need to poke every potentially marked vma,
 * otherwise if task never called for vdso functions
 * page frame number won't be reported.
 *
 * Moreover, if page frame numbers are not accessible
 * we have to scan the vma zone for vDSO elf structure
 * which gonna be a slow way.
 */
static int check_if_vma_is_vdso(enum vdso_check_t vcheck, int pagemap_fd,
	struct parasite_ctl *ctl, struct vma_area *vma,
	struct vma_area **rt_vdso_marked, struct vdso_quarter *addr)
{
	struct parasite_vdso_vma_entry *args;
	bool has_vdso_pfn = false;

	args = compel_parasite_args(ctl, struct parasite_vdso_vma_entry);

	if (not_vvar_or_vdso(vma))
		return 0;

	if ((vma->e->prot & VDSO_PROT) != VDSO_PROT)
		return 0;

	args->start = vma->e->start;
	args->len = vma_area_len(vma);
	args->try_fill_symtable = (vcheck == VDSO_CHECK_SYMS);
	args->is_vdso = false;

	if (compel_rpc_call_sync(PARASITE_CMD_CHECK_VDSO_MARK, ctl)) {
		pr_err("Parasite failed to poke for mark\n");
		return -1;
	}

	if (unlikely(args->is_marked)) {
		if (*rt_vdso_marked) {
			pr_err("Ow! Second vdso mark detected!\n");
			return -1;
		}
		*rt_vdso_marked	= vma;
		addr->orig_vdso	= args->orig_vdso_addr;
		addr->orig_vvar	= args->orig_vvar_addr;
		addr->rt_vvar	= args->rt_vvar_addr;
		return 0;
	}

	if (vcheck == VDSO_NO_CHECK)
		return 0;

	if (vcheck == VDSO_CHECK_PFN) {
		if (check_vdso_by_pfn(pagemap_fd, vma, &has_vdso_pfn) < 0) {
			pr_err("Failed checking vdso by pfn\n");
			return -1;
		}
	}

	if (has_vdso_pfn || args->is_vdso) {
		if (!vma_area_is(vma, VMA_AREA_VDSO)) {
			pr_debug("Restore vDSO status by pfn/symtable at %lx\n",
					(long)vma->e->start);
			vma->e->status |= VMA_AREA_VDSO;
		}
	} else {
		if (unlikely(vma_area_is(vma, VMA_AREA_VDSO))) {
			pr_debug("Drop mishinted vDSO status at %lx\n",
					(long)vma->e->start);
			vma->e->status &= ~VMA_AREA_VDSO;
		}
	}

	return 0;
}

/*
 * The VMAs list might have proxy vdso/vvar areas left
 * from previous dump/restore cycle so we need to detect
 * them and eliminated from the VMAs list, they will be
 * generated again on restore if needed.
 */
int parasite_fixup_vdso(struct parasite_ctl *ctl, pid_t pid,
			struct vm_area_list *vma_area_list)
{
	struct vma_area *rt_vdso_marked = NULL;
	struct vdso_quarter addr = {
		.orig_vdso = VDSO_BAD_ADDR,
		.orig_vvar = VVAR_BAD_ADDR,
		.rt_vdso = VDSO_BAD_ADDR,
		.rt_vvar = VVAR_BAD_ADDR,
	};
	enum vdso_check_t vcheck;
	struct vma_area *vma;
	int fd = -1;

	vcheck = get_vdso_check_type(ctl);
	if (vcheck == VDSO_CHECK_PFN) {
		BUG_ON(vdso_pfn == VDSO_BAD_PFN);
		fd = open_proc(pid, "pagemap");
		if (fd < 0)
			return -1;
	}

	list_for_each_entry(vma, &vma_area_list->h, list) {
		/*
		 * Defer handling marked vdso until we walked over
		 * all vmas and restore potentially remapped vDSO
		 * area status.
		 */
		if (check_if_vma_is_vdso(vcheck, fd, ctl, vma,
					&rt_vdso_marked, &addr)) {
			close_safe(&fd);
			return -1;
		}
	}

	drop_rt_vdso(vma_area_list, &addr, rt_vdso_marked);

	close_safe(&fd);
	return 0;
}

static int vdso_parse_maps(pid_t pid, struct vdso_maps *s)
{
	int exit_code = -1;
	char *buf;
	struct bfd f;

	*s = (struct vdso_maps)VDSO_MAPS_INIT;

	f.fd = open_proc(pid, "maps");
	if (f.fd < 0)
		return -1;

	if (bfdopenr(&f))
		goto err;

	while (1) {
		unsigned long start, end;
		char *has_vdso, *has_vvar;

		buf = breadline(&f);
		if (buf == NULL)
			break;
		if (IS_ERR(buf))
			goto err;

		has_vdso = strstr(buf, "[vdso]");
		if (!has_vdso)
			has_vvar = strstr(buf, "[vvar]");
		else
			has_vvar = NULL;

		if (!has_vdso && !has_vvar)
			continue;

		if (sscanf(buf, "%lx-%lx", &start, &end) != 2) {
			pr_err("Can't find vDSO/VVAR bounds\n");
			goto err;
		}

		if (has_vdso) {
			if (s->vdso_start != VDSO_BAD_ADDR) {
				pr_err("Got second vDSO entry\n");
				goto err;
			}
			s->vdso_start = start;
			s->sym.vdso_size = end - start;
		} else {
			if (s->vvar_start != VVAR_BAD_ADDR) {
				pr_err("Got second VVAR entry\n");
				goto err;
			}
			s->vvar_start = start;
			s->sym.vvar_size = end - start;
		}
	}

	if (s->vdso_start != VDSO_BAD_ADDR && s->vvar_start != VVAR_BAD_ADDR)
		s->sym.vdso_before_vvar = (s->vdso_start < s->vvar_start);

	exit_code = 0;
err:
	bclose(&f);
	return exit_code;
}

static int validate_vdso_addr(struct vdso_maps *s)
{
	unsigned long vdso_end = s->vdso_start + s->sym.vdso_size;
	unsigned long vvar_end = s->vvar_start + s->sym.vvar_size;
	/*
	 * Validate its structure -- for new vDSO format the
	 * structure must be like
	 *
	 * 7fff1f5fd000-7fff1f5fe000 r-xp 00000000 00:00 0 [vdso]
	 * 7fff1f5fe000-7fff1f600000 r--p 00000000 00:00 0 [vvar]
	 *
	 * The areas may be in reverse order.
	 *
	 * 7fffc3502000-7fffc3504000 r--p 00000000 00:00 0 [vvar]
	 * 7fffc3504000-7fffc3506000 r-xp 00000000 00:00 0 [vdso]
	 *
	 */
	if (s->vdso_start != VDSO_BAD_ADDR) {
		if (s->vvar_start != VVAR_BAD_ADDR) {
			if (vdso_end != s->vvar_start &&
			    vvar_end != s->vdso_start) {
				pr_err("Unexpected rt vDSO area bounds\n");
				return -1;
			}
		}
	} else {
		pr_err("Can't find rt vDSO\n");
		return -1;
	}

	return 0;
}

static int vdso_fill_self_symtable(struct vdso_maps *s)
{
	if (s->vdso_start == VDSO_BAD_ADDR || s->sym.vdso_size == VDSO_BAD_SIZE)
		return -1;

	if (vdso_fill_symtable(s->vdso_start, s->sym.vdso_size, &s->sym))
		return -1;

	if (validate_vdso_addr(s))
		return -1;

	pr_debug("rt [vdso] %lx-%lx [vvar] %lx-%lx\n",
		 s->vdso_start, s->vdso_start + s->sym.vdso_size,
		 s->vvar_start, s->vvar_start + s->sym.vvar_size);

	return 0;
}

#ifdef CONFIG_COMPAT
static int vdso_mmap_compat(struct vdso_maps *native,
		struct vdso_maps *compat, void *vdso_buf, size_t buf_size)
{
	pid_t pid;
	int status, ret = -1;
	int fds[2];

	if (pipe(fds)) {
		pr_perror("Failed to open pipe");
		return -1;
	}

	pid = fork();
	if (pid == 0) {
		if (close(fds[1])) {
			pr_perror("Failed to close pipe");
			syscall(__NR_exit, 1);
		}

		compat_vdso_helper(native, fds[0], log_get_fd(),
				vdso_buf, buf_size);

		BUG();
	}

	if (close(fds[0])) {
		pr_perror("Failed to close pipe");
		goto out_kill;
	}
	waitpid(pid, &status, WUNTRACED);

	if (WIFEXITED(status)) {
		pr_err("Compat vdso helper exited with %d\n",
				WEXITSTATUS(status));
		goto out_kill;
	}

	if (!WIFSTOPPED(status)) {
		pr_err("Compat vdso helper isn't stopped\n");
		goto out_kill;
	}

	if (vdso_parse_maps(pid, compat))
		goto out_kill;

	if (validate_vdso_addr(compat))
		goto out_kill;

	if (kill(pid, SIGCONT)) {
		pr_perror("Failed to kill(SIGCONT) for compat vdso helper\n");
		goto out_kill;
	}
	if (write(fds[1], &compat->vdso_start, sizeof(void *)) !=
			sizeof(compat->vdso_start)) {
		pr_perror("Failed write to pipe\n");
		goto out_kill;
	}
	waitpid(pid, &status, WUNTRACED);

	if (WIFEXITED(status)) {
		ret = WEXITSTATUS(status);
		if (ret)
			pr_err("Helper for mmaping compat vdso failed with %d\n", ret);
		goto out_close;
	}
	pr_err("Compat vDSO helper didn't exit, status: %d\n", status);

out_kill:
	kill(pid, SIGKILL);
out_close:
	if (close(fds[1]))
		pr_perror("Failed to close pipe");
	return ret;
}

#define COMPAT_VDSO_BUF_SZ		(PAGE_SIZE*2)
static int vdso_fill_compat_symtable(struct vdso_maps *native,
		struct vdso_maps *compat)
{
	void *vdso_mmap;
	int ret = -1;

	if (!kdat.compat_cr)
		return 0;

	vdso_mmap = mmap(NULL, COMPAT_VDSO_BUF_SZ, PROT_READ | PROT_WRITE,
			MAP_SHARED | MAP_ANONYMOUS, -1, 0);
	if (vdso_mmap == MAP_FAILED) {
		pr_perror("Failed to mmap buf for compat vdso");
		return -1;
	}

	if (vdso_mmap_compat(native, compat, vdso_mmap, COMPAT_VDSO_BUF_SZ)) {
		pr_err("Failed to mmap compatible vdso with helper process\n");
		goto out_unmap;
	}

	if (vdso_fill_symtable_compat((uintptr_t)vdso_mmap,
				compat->sym.vdso_size, &compat->sym)) {
		pr_err("Failed to parse mmaped compatible vdso blob\n");
		goto out_unmap;
	}

	pr_debug("compat [vdso] %lx-%lx [vvar] %lx-%lx\n",
		 compat->vdso_start, compat->vdso_start + compat->sym.vdso_size,
		 compat->vvar_start, compat->vvar_start + compat->sym.vvar_size);
	ret = 0;

out_unmap:
	if (munmap(vdso_mmap, COMPAT_VDSO_BUF_SZ))
		pr_perror("Failed to unmap buf for compat vdso");
	return ret;
}
#endif /* CONFIG_COMPAT */

int vdso_init_dump(void)
{
	if (vdso_parse_maps(PROC_SELF, &vdso_maps)) {
		pr_err("Failed reading self/maps for filling vdso/vvar bounds\n");
		return -1;
	}

	if (kdat.pmap != PM_FULL)
		pr_info("VDSO detection turned off\n");
	else if (vaddr_to_pfn(-1, vdso_maps.vdso_start, &vdso_pfn))
		return -1;

	return 0;
}

/*
 * Check vdso/vvar sized read from maps to kdat values.
 * We do not read /proc/self/maps for compatible vdso as it's
 * not parked as run-time vdso in restorer, but mapped with
 * arch_prlctl(MAP_VDSO_32) API.
 * By that reason we verify only native sizes.
 */
static int is_kdat_vdso_sym_valid(void)
{
	if (vdso_maps.sym.vdso_size != kdat.vdso_sym.vdso_size)
		return false;
	if (vdso_maps.sym.vvar_size != kdat.vdso_sym.vvar_size)
		return false;

	return true;
}

int vdso_init_restore(void)
{
	if (kdat.vdso_sym.vdso_size == VDSO_BAD_SIZE) {
		pr_err("Kdat has empty vdso symtable\n");
		return -1;
	}

	/* Already filled vdso_maps during kdat test */
	if (vdso_maps.vdso_start != VDSO_BAD_ADDR)
		return 0;

	/*
	 * Parsing self-maps here only to find vvar/vdso vmas in
	 * criu's address space, for further remapping to restorer's
	 * parking zone. Don't need to do this if map-vdso API
	 * is present.
	 */
	if (!kdat.can_map_vdso) {
		if (vdso_parse_maps(PROC_SELF, &vdso_maps)) {
			pr_err("Failed reading self/maps for filling vdso/vvar bounds\n");
			return -1;
		}

		if (!is_kdat_vdso_sym_valid()) {
			pr_err("Kdat sizes of vdso/vvar differ to maps file \n");
			return -1;
		}
	}

	vdso_maps.sym = kdat.vdso_sym;
#ifdef CONFIG_COMPAT
	vdso_maps_compat.sym = kdat.vdso_sym_compat;
#endif

	return 0;
}

int kerndat_vdso_fill_symtable(void)
{
	if (vdso_parse_maps(PROC_SELF, &vdso_maps)) {
		pr_err("Failed reading self/maps for filling vdso/vvar bounds\n");
		return -1;
	}

	if (vdso_fill_self_symtable(&vdso_maps)) {
		pr_err("Failed to fill self vdso symtable\n");
		return -1;
	}
	kdat.vdso_sym = vdso_maps.sym;

#ifdef CONFIG_COMPAT
	if (vdso_fill_compat_symtable(&vdso_maps, &vdso_maps_compat)) {
		pr_err("Failed to fill compat vdso symtable\n");
		return -1;
	}
	kdat.vdso_sym_compat = vdso_maps_compat.sym;
#endif

	return 0;
}

/*
 * On x86 pre-v3.16 kernels can lose "[vdso]" hint
 * in /proc/.../maps file after mremap()'ing vdso vma.
 * Depends on kerndat_vdso_fill_symtable() - assuming that
 * vdso_maps and vdso_maps_compat are filled.
 */
int kerndat_vdso_preserves_hint(void)
{
	struct vdso_maps vdso_maps_after;
	int status, ret = -1;
	pid_t child;

	kdat.vdso_hint_reliable = 0;

	if (vdso_maps.vdso_start == VDSO_BAD_ADDR)
		return 0;

	child = fork();
	if (child < 0) {
		pr_perror("fork() failed");
		return -1;
	}

	if (child == 0) {
		unsigned long vdso_addr = vdso_maps.vdso_start;
		unsigned long vdso_size = vdso_maps.sym.vdso_size;
		void *new_addr;

		new_addr = mmap(0, vdso_size, PROT_NONE,
				MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
		if (new_addr == MAP_FAILED)
			exit(1);

		child = getpid();
		new_addr = (void *)syscall(SYS_mremap, vdso_addr, vdso_size,
			vdso_size, MREMAP_MAYMOVE | MREMAP_FIXED, new_addr);
		if (new_addr == MAP_FAILED)
			syscall(SYS_exit, 2);
		syscall(SYS_kill, child, SIGSTOP);
		syscall(SYS_exit, 3);
	}

	waitpid(child, &status, WUNTRACED);
	if (WIFEXITED(status)) {
		int ret = WEXITSTATUS(status);

		pr_err("Child unexpectedly exited with %d\n", ret);
		goto out;
	} else if (WIFSIGNALED(status)) {
		int sig = WTERMSIG(status);

		pr_err("Child unexpectedly signaled with %d: %s\n",
				sig, strsignal(sig));
		goto out;
	} else if (!WIFSTOPPED(status) || WSTOPSIG(status) != SIGSTOP) {
		pr_err("Child is unstoppable or was stopped by other means\n");
		goto out_kill;
	}

	if (vdso_parse_maps(child, &vdso_maps_after)) {
		pr_err("Failed parsing maps for child helper\n");
		goto out_kill;
	}

	if (vdso_maps_after.vdso_start != VDSO_BAD_ADDR)
		kdat.vdso_hint_reliable = 1;

	ret = 0;
out_kill:
	kill(child, SIGKILL);
	waitpid(child, &status, 0);
out:
	return ret;
}
