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Create a function to translate UEFI paths to unix paths

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efivar_device_path_to_unix_path translates from UEFI to Unix
efivar_unix_path_to_device_path translates from Unix to UEFI

At present, only HD() device types are supported (both GPT and
MBR). CdRom and floppy devices aren't supported. ZFS isn't supported
because there's no way in the UEFI standard to specify a ZFS datastore.
Network devices aren't supported either.

Three forms of Unix path are accepted: /path/to/file (for a mounted
filesystem), //path/to/file (uses the EFI partition on the same disk
as /), and dev:/path/to/file (for unmounted filesystem). Two forms are
produced (the first and last).

Sponsored by: Netflix
This commit is contained in:
Warner Losh 2017-12-02 07:29:19 +00:00
parent 64f77f095e
commit 09ee5d8ab6
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=326458
4 changed files with 733 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
lib/libefivar/Makefile
View File

@ -35,6 +35,7 @@ PACKAGE=lib${LIB}
LIB= efivar
SRCS= efivar.c efichar.c efivar-dp-format.c \
efivar-dp-parse.c \
efivar-dp-xlate.c \
uefi-guid.c uefi-dputil.c
INCS= efivar.h efivar-dp.h
SHLIB_MAJOR= 1

13
lib/libefivar/efivar-dp-format.c
View File

@ -2432,7 +2432,7 @@ efidp_format_device_path(char *buf, size_t len, const_efidp dp, ssize_t max)
}
ssize_t
efidp_format_device_path_node(char *buf, size_t len, const_efidp dp, ssize_t max)
efidp_format_device_path_node(char *buf, size_t len, const_efidp dp)
{
char *str;
ssize_t retval;
@ -2454,3 +2454,14 @@ efidp_size(const_efidp dp)
return GetDevicePathSize(__DECONST(EFI_DEVICE_PATH_PROTOCOL *, dp));
}
char *
efidp_extract_file_path(const_efidp dp)
{
const FILEPATH_DEVICE_PATH *fp;
char *name = NULL;
fp = (const void *)dp;
ucs2_to_utf8(fp->PathName, &name);
return name;
}

715
lib/libefivar/efivar-dp-xlate.c Normal file
View File

@ -0,0 +1,715 @@
/*-
* Copyright (c) 2017 Netflix, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer
* in this position and unchanged.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/ucred.h>
#include <sys/mount.h>
#undef MAX
#undef MIN
#include <assert.h>
#include <efivar.h>
#include <errno.h>
#include <libgeom.h>
#include <paths.h>
#include <stdio.h>
#include <string.h>
#include "efichar.h"
#include "efi-osdep.h"
#include "efivar-dp.h"
#include "uefi-dplib.h"
#define MAX_DP_SANITY 4096 /* Biggest device path in bytes */
#define MAX_DP_TEXT_LEN 4096 /* Longest string rep of dp */
#define G_PART "PART"
#define G_LABEL "LABEL"
#define G_DISK "DISK"
static const char *
geom_pp_attr(struct gmesh *mesh, struct gprovider *pp, const char *attr)
{
struct gconfig *conf;
LIST_FOREACH(conf, &pp->lg_config, lg_config) {
if (strcmp(conf->lg_name, attr) != 0)
continue;
return (conf->lg_val);
}
return (NULL);
}
static struct gprovider *
find_provider_by_efimedia(struct gmesh *mesh, const char *efimedia)
{
struct gclass *classp;
struct ggeom *gp;
struct gprovider *pp;
const char *val;
/*
* Find the partition class so we can search it...
*/
LIST_FOREACH(classp, &mesh->lg_class, lg_class) {
if (strcasecmp(classp->lg_name, G_PART) == 0)
break;
}
if (classp == NULL)
return (NULL);
/*
* Each geom will have a number of providers, search each
* one of them for the efimedia that matches.
*/
/* XXX just used gpart class since I know it's the only one, but maybe I should search all classes */
LIST_FOREACH(gp, &classp->lg_geom, lg_geom) {
LIST_FOREACH(pp, &gp->lg_provider, lg_provider) {
val = geom_pp_attr(mesh, pp, "efimedia");
if (val == NULL)
continue;
if (strcasecmp(efimedia, val) == 0)
return (pp);
}
}
return (NULL);
}
static struct gprovider *
find_provider_by_name(struct gmesh *mesh, const char *name)
{
struct gclass *classp;
struct ggeom *gp;
struct gprovider *pp;
LIST_FOREACH(classp, &mesh->lg_class, lg_class) {
LIST_FOREACH(gp, &classp->lg_geom, lg_geom) {
LIST_FOREACH(pp, &gp->lg_provider, lg_provider) {
if (strcmp(pp->lg_name, name) == 0)
return (pp);
}
}
}
return (NULL);
}
static int
efi_hd_to_unix(struct gmesh *mesh, const_efidp dp, char **dev, char **relpath, char **abspath)
{
int rv = 0, n, i;
const_efidp media, file, walker;
size_t len, mntlen;
char buf[MAX_DP_TEXT_LEN];
char *pwalk;
struct gprovider *pp, *provider;
struct gconsumer *cp;
struct statfs *mnt;
walker = media = dp;
/*
* Now, we can either have a filepath node next, or the end.
* Otherwise, it's an error.
*/
walker = (const_efidp)NextDevicePathNode(walker);
if ((uintptr_t)walker - (uintptr_t)dp > MAX_DP_SANITY)
return (EINVAL);
if (DevicePathType(walker) == MEDIA_DEVICE_PATH &&
DevicePathSubType(walker) == MEDIA_FILEPATH_DP)
file = walker;
else if (DevicePathType(walker) == MEDIA_DEVICE_PATH &&
DevicePathType(walker) == END_DEVICE_PATH_TYPE)
file = NULL;
else
return (EINVAL);
/*
* Format this node. We're going to look for it as a efimedia
* attribute of some geom node. Once we find that node, we use it
* as the device it comes from, at least provisionally.
*/
len = efidp_format_device_path_node(buf, sizeof(buf), media);
if (len > sizeof(buf))
return (EINVAL);
pp = find_provider_by_efimedia(mesh, buf);
if (pp == NULL) {
rv = ENOENT;
goto errout;
}
*dev = strdup(pp->lg_name);
if (*dev == NULL) {
rv = ENOMEM;
goto errout;
}
/*
* No file specified, just return the device. Don't even look
* for a mountpoint. XXX Sane?
*/
if (file == NULL)
goto errout;
/*
* Now extract the relative path. The next node in the device path should
* be a filesystem node. If not, we have issues.
*/
*relpath = efidp_extract_file_path(file);
if (*relpath == NULL) {
rv = ENOMEM;
goto errout;
}
for (pwalk = *relpath; *pwalk; pwalk++)
if (*pwalk == '\\')
*pwalk = '/';
/*
* To find the absolute path, we have to look for where we're mounted.
* We only look a little hard, since looking too hard can come up with
* false positives (imagine a graid, one of whose devices is *dev).
*/
n = getfsstat(NULL, 0, MNT_NOWAIT) + 1;
if (n < 0) {
rv = errno;
goto errout;
}
mntlen = sizeof(struct statfs) * n;
mnt = malloc(mntlen);
n = getfsstat(mnt, mntlen, MNT_NOWAIT);
if (n < 0) {
rv = errno;
goto errout;
}
provider = pp;
for (i = 0; i < n; i++) {
/*
* Skip all pseudo filesystems. This also skips the real filesytsem
* of ZFS. There's no EFI designator for ZFS in the standard, so
* we'll need to invent one, but its decoding will be handled in
* a separate function.
*/
if (mnt[i].f_mntfromname[0] != '/')
continue;
/*
* First see if it is directly attached
*/
if (strcmp(provider->lg_name, mnt[i].f_mntfromname + 5) == 0)
break;
/*
* Next see if it is attached via one of the physical disk's
* labels.
*/
LIST_FOREACH(cp, &provider->lg_consumers, lg_consumer) {
pp = cp->lg_provider;
if (strcmp(pp->lg_geom->lg_class->lg_name, G_LABEL) != 0)
continue;
if (strcmp(g_device_path(pp->lg_name), mnt[i].f_mntfromname) == 0)
goto break2;
}
/* Not the one, try the next mount point */
}
break2:
/*
* No mountpoint found, no absolute path possible
*/
if (i >= n)
goto errout;
/*
* Construct absolute path and we're finally done.
*/
if (strcmp(mnt[i].f_mntonname, "/") == 0)
asprintf(abspath, "/%s", *relpath);
else
asprintf(abspath, "%s/%s", mnt[i].f_mntonname, *relpath);
errout:
if (rv != 0) {
free(*dev);
*dev = NULL;
free(*relpath);
*relpath = NULL;
}
return (rv);
}
/*
* Translate the passed in device_path to a unix path via the following
* algorithm.
*
* If dp, dev or path NULL, return EDOOFUS. XXX wise?
*
* Set *path = NULL; *dev = NULL;
*
* Walk through the device_path until we find either a media device path.
* Return EINVAL if not found. Return EINVAL if walking dp would
* land us more than sanity size away from the start (4k).
*
* If we find a media descriptor, we search through the geom mesh to see if we
* can find a matching node. If no match is found in the mesh that matches,
* return ENXIO.
*
* Once we find a matching node, we search to see if there is a filesystem
* mounted on it. If we find nothing, then search each of the devices that are
* mounted to see if we can work up the geom tree to find the matching node. if
* we still can't find anything, *dev = sprintf("/dev/%s", provider_name
* of the original node we found), but return ENOTBLK.
*
* Record the dev of the mountpoint in *dev.
*
* Once we find something, check to see if the next node in the device path is
* the end of list. If so, return the mountpoint.
*
* If the next node isn't a File path node, return EFTYPE.
*
* Extract the path from the File path node(s). translate any \ file separators
* to /. Append the result to the mount point. Copy the resulting path into
* *path. Stat that path. If it is not found, return the errorr from stat.
*
* Finally, check to make sure the resulting path is still on the same
* device. If not, return ENODEV.
*
* Otherwise return 0.
*
* The dev or full path that's returned is malloced, so needs to be freed when
* the caller is done about it. Unlike many other functions, we can return data
* with an error code, so pay attention.
*/
int
efivar_device_path_to_unix_path(const_efidp dp, char **dev, char **relpath, char **abspath)
{
const_efidp walker;
struct gmesh mesh;
int rv = 0;
/*
* Sanity check args, fail early
*/
if (dp == NULL || dev == NULL || relpath == NULL || abspath == NULL)
return (EDOOFUS);
*dev = NULL;
*relpath = NULL;
*abspath = NULL;
/*
* Find the first media device path we can. If we go too far,
* assume the passed in device path is bogus. If we hit the end
* then we didn't find a media device path, so signal that error.
*/
walker = dp;
while (DevicePathType(walker) != MEDIA_DEVICE_PATH &&
DevicePathType(walker) != END_DEVICE_PATH_TYPE) {
walker = (const_efidp)NextDevicePathNode(walker);
if ((uintptr_t)walker - (uintptr_t)dp > MAX_DP_SANITY)
return (EINVAL);
}
if (DevicePathType(walker) != MEDIA_DEVICE_PATH)
return (EINVAL);
/*
* There's several types of media paths. We're only interested in the
* hard disk path, as it's really the only relevant one to booting. The
* CD path just might also be relevant, and would be easy to add, but
* isn't supported. A file path too is relevant, but at this stage, it's
* premature because we're trying to translate a specification for a device
* and path on that device into a unix path, or at the very least, a
* geom device : path-on-device.
*
* Also, ZFS throws a bit of a monkey wrench in here since it doesn't have
* a device path type (it creates a new virtual device out of one or more
* storage devices).
*
* For all of them, we'll need to know the geoms, so allocate / free the
* geom mesh here since it's safer than doing it in each sub-function
* which may have many error exits.
*/
if (geom_gettree(&mesh))
return (ENOMEM);
rv = EINVAL;
if (DevicePathSubType(walker) == MEDIA_HARDDRIVE_DP)
rv = efi_hd_to_unix(&mesh, walker, dev, relpath, abspath);
#ifdef notyet
else if (is_cdrom_device(walker))
rv = efi_cdrom_to_unix(&mesh, walker, dev, relpath, abspath);
else if (is_floppy_device(walker))
rv = efi_floppy_to_unix(&mesh, walker, dev, relpath, abspath);
else if (is_zpool_device(walker))
rv = efi_zpool_to_unix(&mesh, walker, dev, relpath, abspath);
#endif
geom_deletetree(&mesh);
return (rv);
}
/*
* Construct the EFI path to a current unix path as follows.
*
* The path may be of one of three forms:
* 1) /path/to/file -- full path to a file. The file need not be present,
* but /path/to must be. It must reside on a local filesystem
* mounted on a GPT or MBR partition.
* 2) //path/to/file -- Shorthand for 'On the EFI partition, \path\to\file'
* where 'The EFI Partition' is a partiton that's type is 'efi'
* on the same disk that / is mounted from. If there are multiple
* or no 'efi' parittions on that disk, or / isn't on a disk that
* we can trace back to a physical device, an error will result
* 3) [/dev/]geom-name:/path/to/file -- Use the specified partition
* (and it must be a GPT or MBR partition) with the specified
* path. The latter is not authenticated.
* all path forms translate any \ characters to / before further processing.
* When a file path node is created, all / characters are translated back
* to \.
*
* For paths of the first form:
* find where the filesystem is mount (either the file directly, or
* its parent directory).
* translate any logical device name (eg lable) to a physical one
* If not possible, return ENXIO
* If the physical path is unsupported (Eg not on a GPT or MBR disk),
* return ENXIO
* Create a media device path node.
* append the relative path from the mountpoint to the media device node
* as a file path.
*
* For paths matching the second form:
* find the EFI partition corresponding to the root fileystem.
* If none found, return ENXIO
* Create a media device path node for the found partition
* Append a File Path to the end for the rest of the file.
*
* For paths of the third form
* Translate the geom-name passed in into a physical partition
* name.
* Return ENXIO if the translation fails
* Make a media device path for it
* append the part after the : as a File path node.
*/
static char *
path_to_file_dp(const char *relpath)
{
char *rv;
asprintf(&rv, "File(%s)", relpath);
return rv;
}
static char *
find_geom_efi_on_root(struct gmesh *mesh)
{
struct statfs buf;
const char *dev;
struct gprovider *pp;
// struct ggeom *disk;
struct gconsumer *cp;
/*
* Find /'s geom. Assume it's mounted on /dev/ and filter out all the
* filesystems that aren't.
*/
if (statfs("/", &buf) != 0)
return (NULL);
dev = buf.f_mntfromname;
if (*dev != '/' || strncmp(dev, _PATH_DEV, sizeof(_PATH_DEV) - 1) != 0)
return (NULL);
dev += sizeof(_PATH_DEV) -1;
pp = find_provider_by_name(mesh, dev);
if (pp == NULL)
return (NULL);
/*
* If the provider is a LABEL, find it's outer PART class, if any. We
* only operate on partitions.
*/
if (strcmp(pp->lg_geom->lg_class->lg_name, G_LABEL) == 0) {
LIST_FOREACH(cp, &pp->lg_consumers, lg_consumer) {
if (strcmp(cp->lg_provider->lg_geom->lg_class->lg_name, G_PART) == 0) {
pp = cp->lg_provider;
break;
}
}
}
if (strcmp(pp->lg_geom->lg_class->lg_name, G_PART) != 0)
return (NULL);
#if 0
/* This doesn't work because we can't get the data to walk UP the tree it seems */
/*
* Now that we've found the PART that we have mounted as root, find the
* first efi typed partition that's a peer, if any.
*/
LIST_FOREACH(cp, &pp->lg_consumers, lg_consumer) {
if (strcmp(cp->lg_provider->lg_geom->lg_class->lg_name, G_DISK) == 0) {
disk = cp->lg_provider->lg_geom;
break;
}
}
if (disk == NULL) /* This is very bad -- old nested partitions -- no support ? */
return (NULL);
#endif
#if 0
/* This doesn't work because we can't get the data to walk UP the tree it seems */
/*
* With the disk provider, we can look for its consumers to see if any are the proper type.
*/
LIST_FOREACH(pp, &disk->lg_consumer, lg_consumer) {
type = geom_pp_attr(mesh, pp, "type");
if (type == NULL)
continue;
if (strcmp(type, "efi") != 0)
continue;
efimedia = geom_pp_attr(mesh, pp, "efimedia");
if (efimedia == NULL)
return (NULL);
return strdup(efimedia);
}
#endif
return (NULL);
}
static char *
find_geom_efimedia(struct gmesh *mesh, const char *dev)
{
struct gprovider *pp;
const char *efimedia;
pp = find_provider_by_name(mesh, dev);
if (pp == NULL)
return (NULL);
efimedia = geom_pp_attr(mesh, pp, "efimedia");
if (efimedia == NULL)
return (NULL);
return strdup(efimedia);
}
static int
build_dp(const char *efimedia, const char *relpath, efidp *dp)
{
char *fp, *dptxt = NULL;
int rv = 0;
efidp out;
size_t len;
fp = path_to_file_dp(relpath);
if (fp == NULL) {
rv = ENOMEM;
goto errout;
}
asprintf(&dptxt, "%s/%s", efimedia, fp);
out = malloc(8192);
len = efidp_parse_device_path(dptxt, out, 8192);
if (len > 8192) {
rv = ENOMEM;
goto errout;
}
if (len == 0) {
rv = EINVAL;
goto errout;
}
*dp = out;
errout:
if (rv) {
free(out);
}
free(dptxt);
free(fp);
return rv;
}
/* Handles //path/to/file */
/*
* Which means: find the disk that has /. Then look for a EFI partition
* and use that for the efimedia and /path/to/file as relative to that.
* Not sure how ZFS will work here since we can't easily make the leap
* to the geom from the zpool.
*/
static int
efipart_to_dp(struct gmesh *mesh, char *path, efidp *dp)
{
char *efimedia = NULL;
int rv;
efimedia = find_geom_efi_on_root(mesh);
#ifdef notyet
if (efimedia == NULL)
efimedia = find_efi_on_zfsroot(dev);
#endif
if (efimedia == NULL) {
rv = ENOENT;
goto errout;
}
rv = build_dp(efimedia, path + 1, dp);
errout:
free(efimedia);
return rv;
}
/* Handles [/dev/]geom:[/]path/to/file */
/* Handles zfs-dataset:[/]path/to/file (this may include / ) */
static int
dev_path_to_dp(struct gmesh *mesh, char *path, efidp *dp)
{
char *relpath, *dev, *efimedia = NULL;
int rv = 0;
relpath = strchr(path, ':');
assert(relpath != NULL);
*relpath++ = '\0';
dev = path;
if (strncmp(dev, _PATH_DEV, sizeof(_PATH_DEV) - 1) == 0)
dev += sizeof(_PATH_DEV) -1;
efimedia = find_geom_efimedia(mesh, dev);
#ifdef notyet
if (efimedia == NULL)
find_zfs_efi_media(dev);
#endif
if (efimedia == NULL) {
rv = ENOENT;
goto errout;
}
rv = build_dp(efimedia, relpath, dp);
errout:
free(efimedia);
return rv;
}
/* Handles /path/to/file */
static int
path_to_dp(struct gmesh *mesh, char *path, efidp *dp)
{
struct statfs buf;
char *rp = NULL, *ep, *dev, *efimedia = NULL;
int rv = 0;
rp = realpath(path, NULL);
if (rp == NULL) {
rv = errno;
goto errout;
}
if (statfs(rp, &buf) != 0) {
rv = errno;
goto errout;
}
dev = buf.f_mntfromname;
if (strncmp(dev, _PATH_DEV, sizeof(_PATH_DEV) - 1) == 0)
dev += sizeof(_PATH_DEV) -1;
ep = rp + strlen(buf.f_mntonname);
efimedia = find_geom_efimedia(mesh, dev);
#ifdef notyet
if (efimedia == NULL)
find_zfs_efi_media(dev);
#endif
if (efimedia == NULL) {
rv = ENOENT;
goto errout;
}
rv = build_dp(efimedia, ep, dp);
errout:
free(efimedia);
free(rp);
if (rv != 0) {
free(*dp);
}
return (rv);
}
int
efivar_unix_path_to_device_path(const char *path, efidp *dp)
{
char *modpath = NULL, *cp;
int rv = ENOMEM;
struct gmesh mesh;
/*
* Fail early for clearly bogus things
*/
if (path == NULL || dp == NULL)
return (EDOOFUS);
/*
* We'll need the goem mesh to grovel through it to find the
* efimedia attribute for any devices we find. Grab it here
* and release it to simplify the error paths out of the
* subordinate functions
*/
if (geom_gettree(&mesh))
return (errno);
/*
* Convert all \ to /. We'll convert them back again when
* we encode the file. Boot loaders are expected to cope.
*/
modpath = strdup(path);
if (modpath == NULL)
goto out;
for (cp = modpath; *cp; cp++)
if (*cp == '\\')
*cp = '/';
if (modpath[0] == '/' && modpath[1] == '/') /* Handle //foo/bar/baz */
rv = efipart_to_dp(&mesh, modpath, dp);
else if (strchr(modpath, ':')) /* Handle dev:/bar/baz */
rv = dev_path_to_dp(&mesh, modpath, dp);
else /* Handle /a/b/c */
rv = path_to_dp(&mesh, modpath, dp);
out:
geom_deletetree(&mesh);
free(modpath);
return (rv);
}

7
lib/libefivar/efivar-dp.h
View File

@ -60,10 +60,13 @@ typedef const efidp_data *const_efidp;
*/
ssize_t efidp_format_device_path(char *buf, size_t len, const_efidp dp,
ssize_t max);
ssize_t efidp_format_device_path_node(char *buf, size_t len, const_efidp dp,
ssize_t max);
ssize_t efidp_format_device_path_node(char *buf, size_t len, const_efidp dp);
ssize_t efidp_parse_device_path(char *path, efidp out, size_t max);
char * efidp_extract_file_path(const_efidp dp);
size_t efidp_size(const_efidp);
int efivar_device_path_to_unix_path(const_efidp dp, char **dev, char **relpath, char **abspath);
int efivar_unix_path_to_device_path(const char *path, efidp *dp);
#endif /* _EFIVAR_DP_H_ */