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grub/grub-core/fs/cpio.c
Vladimir 'phcoder' Serbinenko 19ee298767 Handle symlinks and long names on tar and cpio. 
* grub-core/fs/cpio.c (ATTR_TYPE): New definition.
	(ATTR_FILE): Likewise.
	(ATTR_DIR): Likewise.
	(ATTR_LNK): Likewise.
	(grub_cpio_data) [MODE_USTAR]: New fields linkname and linkname_alloc.
	(grub_cpio_find_file): Fill mode, handle linkname field as well as
	L and K entries.
	(grub_cpio_mount): Zero-fill data.
	(handle_symlink): New function.
2011-10-30 23:06:25 +01:00

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/* cpio.c - cpio and tar filesystem. */
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2007,2008,2009 Free Software Foundation, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <grub/file.h>
#include <grub/mm.h>
#include <grub/misc.h>
#include <grub/disk.h>
#include <grub/dl.h>
GRUB_MOD_LICENSE ("GPLv3+");
#define ATTR_TYPE 0160000
#define ATTR_FILE 0100000
#define ATTR_DIR 0040000
#define ATTR_LNK 0120000
#ifndef MODE_USTAR
/* cpio support */
#define MAGIC_BCPIO 070707
struct head
{
grub_uint16_t magic;
grub_uint16_t dev;
grub_uint16_t ino;
grub_uint16_t mode;
grub_uint16_t uid;
grub_uint16_t gid;
grub_uint16_t nlink;
grub_uint16_t rdev;
grub_uint16_t mtime_1;
grub_uint16_t mtime_2;
grub_uint16_t namesize;
grub_uint16_t filesize_1;
grub_uint16_t filesize_2;
} __attribute__ ((packed));
#else
/* tar support */
#define MAGIC_USTAR "ustar"
struct head
{
char name[100];
char mode[8];
char uid[8];
char gid[8];
char size[12];
char mtime[12];
char chksum[8];
char typeflag;
char linkname[100];
char magic[6];
char version[2];
char uname[32];
char gname[32];
char devmajor[8];
char devminor[8];
char prefix[155];
} __attribute__ ((packed));
#endif
struct grub_cpio_data
{
grub_disk_t disk;
grub_off_t hofs;
grub_off_t dofs;
grub_off_t size;
#ifdef MODE_USTAR
char *linkname;
grub_size_t linkname_alloc;
#endif
};
static grub_dl_t my_mod;
static inline void
canonicalize (char *name)
{
char *iptr, *optr;
for (iptr = name, optr = name; *iptr; )
{
while (*iptr == '/')
iptr++;
if (iptr[0] == '.' && (iptr[1] == '/' || iptr[1] == 0))
{
iptr += 2;
continue;
}
while (*iptr && *iptr != '/')
*optr++ = *iptr++;
if (*iptr)
*optr++ = *iptr++;
}
*optr = 0;
}
static grub_err_t
grub_cpio_find_file (struct grub_cpio_data *data, char **name,
grub_int32_t *mtime, grub_disk_addr_t *ofs,
grub_uint32_t *mode)
{
#ifndef MODE_USTAR
struct head hd;
if (grub_disk_read (data->disk, 0, data->hofs, sizeof (hd), &hd))
return grub_errno;
if (hd.magic != MAGIC_BCPIO)
return grub_error (GRUB_ERR_BAD_FS, "invalid cpio archive");
data->size = (((grub_uint32_t) hd.filesize_1) << 16) + hd.filesize_2;
if (mtime)
*mtime = (((grub_uint32_t) hd.mtime_1) << 16) + hd.mtime_2;
if (mode)
*mode = hd.mode;
if (hd.namesize & 1)
hd.namesize++;
*name = grub_malloc (hd.namesize + 1);
if (*name == NULL)
return grub_errno;
if (grub_disk_read (data->disk, 0, data->hofs + sizeof (hd),
hd.namesize, *name))
{
grub_free (*name);
return grub_errno;
}
(*name)[hd.namesize] = 0;
if (data->size == 0 && hd.mode == 0 && hd.namesize == 11 + 1
&& grub_memcmp(*name, "TRAILER!!!", 11) == 0)
{
*ofs = 0;
return GRUB_ERR_NONE;
}
canonicalize (*name);
data->dofs = data->hofs + sizeof (hd) + hd.namesize;
*ofs = data->dofs + data->size;
if (data->size & 1)
(*ofs)++;
#else
struct head hd;
int reread = 0, have_longname = 0, have_longlink = 0;
for (reread = 0; reread < 3; reread++)
{
if (grub_disk_read (data->disk, 0, data->hofs, sizeof (hd), &hd))
return grub_errno;
if (!hd.name[0])
{
*ofs = 0;
return GRUB_ERR_NONE;
}
if (grub_memcmp (hd.magic, MAGIC_USTAR, sizeof (MAGIC_USTAR) - 1))
return grub_error (GRUB_ERR_BAD_FS, "invalid tar archive");
if (hd.typeflag == 'L')
{
grub_err_t err;
grub_size_t namesize = grub_strtoull (hd.size, NULL, 8);
*name = grub_malloc (namesize + 1);
if (*name == NULL)
return grub_errno;
err = grub_disk_read (data->disk, 0,
data->hofs + GRUB_DISK_SECTOR_SIZE, namesize,
*name);
(*name)[namesize] = 0;
if (err)
return err;
data->hofs += GRUB_DISK_SECTOR_SIZE
+ ((namesize + GRUB_DISK_SECTOR_SIZE - 1) &
~(GRUB_DISK_SECTOR_SIZE - 1));
have_longname = 1;
continue;
}
if (hd.typeflag == 'K')
{
grub_err_t err;
grub_size_t linksize = grub_strtoull (hd.size, NULL, 8);
if (data->linkname_alloc < linksize + 1)
{
char *n;
n = grub_malloc (2 * (linksize + 1));
if (!n)
return grub_errno;
grub_free (data->linkname);
data->linkname = n;
data->linkname_alloc = 2 * (linksize + 1);
}
err = grub_disk_read (data->disk, 0,
data->hofs + GRUB_DISK_SECTOR_SIZE, linksize,
data->linkname);
if (err)
return err;
data->linkname[linksize] = 0;
data->hofs += GRUB_DISK_SECTOR_SIZE
+ ((linksize + GRUB_DISK_SECTOR_SIZE - 1) &
~(GRUB_DISK_SECTOR_SIZE - 1));
have_longlink = 1;
continue;
}
if (!have_longname)
{
*name = grub_strdup (hd.name);
if (*name == NULL)
return grub_errno;
}
data->size = grub_strtoull (hd.size, NULL, 8);
data->dofs = data->hofs + GRUB_DISK_SECTOR_SIZE;
*ofs = data->dofs + ((data->size + GRUB_DISK_SECTOR_SIZE - 1) &
~(GRUB_DISK_SECTOR_SIZE - 1));
if (mtime)
*mtime = grub_strtoul (hd.mtime, NULL, 8);
if (mode)
{
*mode = grub_strtoul (hd.mode, NULL, 8);
switch (hd.typeflag)
{
case '2':
*mode |= ATTR_LNK;
break;
case '0':
*mode |= ATTR_FILE;
break;
case '5':
*mode |= ATTR_DIR;
break;
}
}
if (!have_longlink)
{
if (data->linkname_alloc < 101)
{
char *n;
n = grub_malloc (101);
if (!n)
return grub_errno;
grub_free (data->linkname);
data->linkname = n;
data->linkname_alloc = 101;
}
grub_memcpy (data->linkname, hd.linkname, sizeof (hd.linkname));
data->linkname[100] = 0;
}
canonicalize (*name);
return GRUB_ERR_NONE;
}
#endif
return GRUB_ERR_NONE;
}
static struct grub_cpio_data *
grub_cpio_mount (grub_disk_t disk)
{
struct head hd;
struct grub_cpio_data *data;
if (grub_disk_read (disk, 0, 0, sizeof (hd), &hd))
goto fail;
#ifndef MODE_USTAR
if (hd.magic != MAGIC_BCPIO)
#else
if (grub_memcmp (hd.magic, MAGIC_USTAR,
sizeof (MAGIC_USTAR) - 1))
#endif
goto fail;
data = (struct grub_cpio_data *) grub_zalloc (sizeof (*data));
if (!data)
goto fail;
data->disk = disk;
return data;
fail:
grub_error (GRUB_ERR_BAD_FS, "not a "
#ifdef MODE_USTAR
"tar"
#else
"cpio"
#endif
" filesystem");
return 0;
}
static grub_err_t
handle_symlink (struct grub_cpio_data *data,
const char *fn, char **name,
grub_uint32_t mode, int *restart)
{
grub_size_t flen;
char *target;
#ifndef MODE_USTAR
grub_err_t err;
#endif
char *ptr;
char *lastslash;
grub_size_t prefixlen;
char *rest;
grub_size_t size;
*restart = 0;
if ((mode & ATTR_TYPE) != ATTR_LNK)
return GRUB_ERR_NONE;
flen = grub_strlen (fn);
if (grub_memcmp (*name, fn, flen) != 0
|| ((*name)[flen] != 0 && (*name)[flen] != '/'))
return GRUB_ERR_NONE;
rest = *name + flen;
lastslash = rest;
if (*rest)
rest++;
while (lastslash >= *name && *lastslash != '/')
lastslash--;
if (lastslash >= *name)
prefixlen = lastslash - *name;
else
prefixlen = 0;
if (prefixlen)
prefixlen++;
#ifdef MODE_USTAR
size = grub_strlen (data->linkname);
#else
size = data->size;
#endif
if (size == 0)
return GRUB_ERR_NONE;
target = grub_malloc (size + grub_strlen (*name) + 2);
if (!target)
return grub_errno;
#ifdef MODE_USTAR
grub_memcpy (target + prefixlen, data->linkname, size);
#else
err = grub_disk_read (data->disk, 0, data->dofs, data->size,
target + prefixlen);
if (err)
return err;
#endif
if (target[prefixlen] == '/')
{
grub_memmove (target, target + prefixlen, data->size - 1);
ptr = target + data->size - 1;
ptr = grub_stpcpy (ptr, rest);
*ptr = 0;
grub_dprintf ("cpio", "symlink redirected %s to %s\n",
*name, target);
grub_free (*name);
*name = target;
*restart = 1;
return GRUB_ERR_NONE;
}
if (prefixlen)
{
grub_memcpy (target, *name, prefixlen);
target[prefixlen] = '/';
}
ptr = target + prefixlen + size;
ptr = grub_stpcpy (ptr, rest);
*ptr = 0;
grub_dprintf ("cpio", "symlink redirected %s to %s\n",
*name, target);
grub_free (*name);
*name = target;
*restart = 1;
return GRUB_ERR_NONE;
}
static grub_err_t
grub_cpio_dir (grub_device_t device, const char *path_in,
int (*hook) (const char *filename,
const struct grub_dirhook_info *info))
{
struct grub_cpio_data *data;
grub_disk_addr_t ofs;
char *prev, *name, *path;
grub_size_t len;
int symlinknest = 0;
path = grub_strdup (path_in + 1);
if (!path)
return grub_errno;
grub_dl_ref (my_mod);
prev = 0;
data = grub_cpio_mount (device->disk);
if (!data)
{
grub_free (path);
return grub_errno;
}
len = grub_strlen (path);
data->hofs = 0;
while (1)
{
grub_int32_t mtime;
grub_uint32_t mode;
grub_err_t err;
if (grub_cpio_find_file (data, &name, &mtime, &ofs, &mode))
goto fail;
if (!ofs)
break;
if (grub_memcmp (path, name, len) == 0
&& (name[len] == 0 || name[len] == '/' || len == 0))
{
char *p, *n;
n = name + len;
if (*n == '/')
n++;
p = grub_strchr (name + len, '/');
if (p)
*p = 0;
if (((!prev) || (grub_strcmp (prev, name) != 0)) && name[len] != 0)
{
struct grub_dirhook_info info;
grub_memset (&info, 0, sizeof (info));
info.dir = (p != NULL);
info.mtime = mtime;
info.mtimeset = 1;
hook (name + len, &info);
grub_free (prev);
prev = name;
}
else
{
int restart;
err = handle_symlink (data, name, &path, mode, &restart);
grub_free (name);
if (err)
goto fail;
if (restart)
{
len = grub_strlen (path);
if (++symlinknest == 8)
{
grub_error (GRUB_ERR_SYMLINK_LOOP,
"too deep nesting of symlinks");
goto fail;
}
ofs = 0;
}
}
}
data->hofs = ofs;
}
fail:
grub_free (path);
grub_free (prev);
#ifdef MODE_USTAR
grub_free (data->linkname);
#endif
grub_free (data);
grub_dl_unref (my_mod);
return grub_errno;
}
static grub_err_t
grub_cpio_open (grub_file_t file, const char *name_in)
{
struct grub_cpio_data *data;
grub_disk_addr_t ofs;
char *fn;
char *name = grub_strdup (name_in + 1);
int symlinknest = 0;
if (!name)
return grub_errno;
grub_dl_ref (my_mod);
data = grub_cpio_mount (file->device->disk);
if (!data)
{
grub_free (name);
return grub_errno;
}
data->hofs = 0;
while (1)
{
grub_uint32_t mode;
int restart;
if (grub_cpio_find_file (data, &fn, NULL, &ofs, &mode))
goto fail;
if (!ofs)
{
grub_error (GRUB_ERR_FILE_NOT_FOUND, "file not found");
break;
}
if (handle_symlink (data, fn, &name, mode, &restart))
{
grub_free (fn);
goto fail;
}
if (restart)
{
ofs = 0;
if (++symlinknest == 8)
{
grub_error (GRUB_ERR_SYMLINK_LOOP,
"too deep nesting of symlinks");
goto fail;
}
goto no_match;
}
if (grub_strcmp (name, fn) != 0)
goto no_match;
file->data = data;
file->size = data->size;
grub_free (fn);
grub_free (name);
return GRUB_ERR_NONE;
no_match:
grub_free (fn);
data->hofs = ofs;
}
fail:
#ifdef MODE_USTAR
grub_free (data->linkname);
#endif
grub_free (data);
grub_free (name);
grub_dl_unref (my_mod);
return grub_errno;
}
static grub_ssize_t
grub_cpio_read (grub_file_t file, char *buf, grub_size_t len)
{
struct grub_cpio_data *data;
data = file->data;
return (grub_disk_read (data->disk, 0, data->dofs + file->offset,
len, buf)) ? -1 : (grub_ssize_t) len;
}
static grub_err_t
grub_cpio_close (grub_file_t file)
{
struct grub_cpio_data *data;
data = file->data;
#ifdef MODE_USTAR
grub_free (data->linkname);
#endif
grub_free (data);
grub_dl_unref (my_mod);
return grub_errno;
}
static struct grub_fs grub_cpio_fs = {
#ifdef MODE_USTAR
.name = "tarfs",
#else
.name = "cpiofs",
#endif
.dir = grub_cpio_dir,
.open = grub_cpio_open,
.read = grub_cpio_read,
.close = grub_cpio_close,
#ifdef GRUB_UTIL
.reserved_first_sector = 0,
#endif
};
#ifdef MODE_USTAR
GRUB_MOD_INIT (tar)
#else
GRUB_MOD_INIT (cpio)
#endif
{
grub_fs_register (&grub_cpio_fs);
my_mod = mod;
}
#ifdef MODE_USTAR
GRUB_MOD_FINI (tar)
#else
GRUB_MOD_FINI (cpio)
#endif
{
grub_fs_unregister (&grub_cpio_fs);
}
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