There are two distinct uses of an arbitrary buffers size when querying
the device mapper. One is related to loading the /proc/devices file,
while the other is used as buffer for ioctls to the devmapper.
Split up the macros used here so that it's clear that they are not meant
for the same thing.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
For reasons unknown, when rewriting this code and dropping
libdevmapper I've mistakenly used incorrect length of dm.name. In
linux/dm-ioctl.h the dm_ioctl struct is defined as follows:
#define DM_NAME_LEN 128
struct dm_ioctl {
...
char name[DM_NAME_LEN]; /* device name */
...
};
However, when copying string into this member, DM_TABLE_DEPS was
used, which is defined as follows:
#define DM_TABLE_DEPS _IOWR(DM_IOCTL, DM_TABLE_DEPS_CMD, struct dm_ioctl)
After decryption, this results in the following size: 3241737483.
Fixes: 2249455654
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
virStrncpy was called with -1 for length of the copied source which is
equivalent to virStrcpy.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Our implementation was heavily inspired by the glib version so it's a
drop-in replacement.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Glib provides g_auto(GStrv) which is in-place replacement of our
VIR_AUTOSTRINGLIST.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Introduced by commit <22494556542c676d1b9e7f1c1f2ea13ac17e1e3e> which
fixed a CVE.
If the @path passed to virDMSanitizepath() is not a DM name or not a
path to DM name this function could return incorrect sanitized path as
it would always be the first device under /dev/mapper/.
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
After converting all DIR* to g_autoptr(DIR), many cleanup: labels
ended up just having "return ret", and every place that set ret would
just immediately goto cleanup. Remove the cleanup label and its
return, and just return the set value immediately, thus eliminating
the need for the return variable itself.
Signed-off-by: Laine Stump <laine@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
All of these conversions are trivial - VIR_DIR_CLOSE() (aka
virDirClose()) is called only once on the DIR*, and it happens just
before going out of scope.
Signed-off-by: Laine Stump <laine@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
This will make it easier to review upcoming patches that use g_autoptr
to auto-close all DIRs.
Signed-off-by: Laine Stump <laine@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
So far, only ENOENT is ignored (to deal with kernels without
devmapper). However, as reported on the list, under certain
scenarios a different error can occur. For instance, when libvirt
is running inside a container which doesn't have permissions to
talk to the devmapper. If this is the case, then open() returns
-1 and sets errno=EPERM.
Assuming that multipath devices are fairly narrow use case and
using them in a restricted container is even more narrow the best
fix seems to be to ignore all open errors BUT produce a warning
on failure. To avoid flooding logs with warnings on kernels
without devmapper the level is reduced to a plain debug message.
Reported-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Reviewed-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
In one of my latest patch (v6.6.0~30) I was trying to remove
libdevmapper use in favor of our own implementation. However, the
code did not take into account that device mapper can be not
compiled into the kernel (e.g. be a separate module that's not
loaded) in which case /proc/devices won't have the device-mapper
major number and thus virDevMapperGetTargets() and/or
virIsDevMapperDevice() fails.
However, such failure is safe to ignore, because if device mapper
is missing then there can't be any multipath devices and thus we
don't need to allow the deps in CGroups, nor create them in the
domain private namespace, etc.
Fixes: 2249455654
Reported-by: Andrea Bolognani <abologna@redhat.com>
Reported-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Tested-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
The device mapper major is needed in virIsDevMapperDevice() which
determines whether given device is managed by device-mapper. This
number is obtained by parsing /proc/devices and then stored in a
global variable so that the file doesn't have to be parsed again.
However, as it turns out this logic is flawed - the major number
is not static and can change as it can be specified as a
parameter when loading the dm-mod module.
Unfortunately, I was not able to come up with a good solution and
thus the /proc/devices file is being parsed every time we need
the device mapper major.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Tested-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
These variables are only used for assignment and have
no other effect.
Signed-off-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Pavel Hrdina <phrdina@redhat.com>
CVE-2020-14339
When building domain's private /dev in a namespace, libdevmapper
is consulted for getting full dependency tree of domain's disks.
The reason is that for a multipath devices all dependent devices
must be created in the namespace and allowed in CGroups.
However, this approach is very fragile as building of namespace
happens in the forked off child process, after mass close of FDs
and just before dropping privileges and execing QEMU. And it so
happens that when calling libdevmapper APIs, one of them opens
/dev/mapper/control and saves the FD into a global variable. The
FD is kept open until the lib is unlinked or dm_lib_release() is
called explicitly. We are doing neither.
However, the virDevMapperGetTargets() function is called also
from libvirtd (when setting up CGroups) and thus has to be thread
safe. Unfortunately, libdevmapper APIs are not thread safe (nor
async signal safe) and thus we can't use them. Reimplement what
libdevmapper would do using plain C (ioctl()-s, /proc/devices
parsing, /dev/mapper dirwalking, and so on).
Fixes: a30078cb83
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1858260
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Since we have VIR_AUTOSTRINGLIST we can use it to free string
lists used in the function automatically.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
There are two distinct WITH_DEVMAPPER sections in the file, for
different functions each. Rearrange the code to make some of
future commits smaller.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
In v6.4.0-rc1~143 I've introduced a check that is supposed to
return from the function early, if given path is not a dm target.
While the idea is still valid, the implementation had a flaw.
It calls stat() over given path and the uses major(sb.st_dev) to
learn the major of the device. This is then passed to
dm_is_dm_major() which returns true or false depending whether
the device is under devmapper's control or not.
The problem with this approach is in how the major of the device
is obtained - paths managed by devmapper are special files and
thus we want to be using st_rdev instead of st_dev to obtain the
major number. Well, that's what virIsDevMapperDevice() does
already so might as well us that.
Fixes: 01626c668e
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1839992
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
When introducing virdevmapper.c (in v4.3.0-rc1~427) I didn't
realize there is a function that calls in devmapper. The function
is called virIsDevMapperDevice() and lives in virutil.c. Now that
we have a special file for handling devmapper move it there.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
As suggested in the linked bug, libvirt should firstly check
whether the major number of the device is device mapper major.
Because if it isn't subsequent DM_DEVICE_DEPS task may not only
fail, but also yield different results. In the bugzilla this is
demonstrated by creating a devmapper target named 'loop0' and
then creating loop target /dev/loop0. When the latter is then
passed to a domain, our virDevMapperGetTargetsImpl() function
blindly asks devmapper to provide target dependencies for
/dev/loop0 and because of the way devmapper APIs work, it will
'sanitize' the input by using the last component only which is
'loop0' and thus return different results than expected.
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1823976
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
All our supported Linux distros now have this header.
It has never existed on FreeBSD / macOS / Mingw.
Reviewed-by: Pavel Hrdina <phrdina@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Use G_GNUC_UNUSED from GLib instead of ATTRIBUTE_UNUSED.
Signed-off-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Missing semicolon at the end of macros can confuse some analyzers
(like cppcheck <filename>). VIR_ONCE_GLOBAL_INIT is almost
exclusively called without an ending semicolon, but let's
standardize on using one like the other macros.
Add a dummy struct definition at the end of the macro, so
the compiler will require callers to add a semicolon.
Reviewed-by: John Ferlan <jferlan@redhat.com>
Signed-off-by: Cole Robinson <crobinso@redhat.com>
In many files there are header comments that contain an Author:
statement, supposedly reflecting who originally wrote the code.
In a large collaborative project like libvirt, any non-trivial
file will have been modified by a large number of different
contributors. IOW, the Author: comments are quickly out of date,
omitting people who have made significant contribitions.
In some places Author: lines have been added despite the person
merely being responsible for creating the file by moving existing
code out of another file. IOW, the Author: lines give an incorrect
record of authorship.
With this all in mind, the comments are useless as a means to identify
who to talk to about code in a particular file. Contributors will always
be better off using 'git log' and 'git blame' if they need to find the
author of a particular bit of code.
This commit thus deletes all Author: comments from the source and adds
a rule to prevent them reappearing.
The Copyright headers are similarly misleading and inaccurate, however,
we cannot delete these as they have legal meaning, despite being largely
inaccurate. In addition only the copyright holder is permitted to change
their respective copyright statement.
Reviewed-by: Erik Skultety <eskultet@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
https://bugzilla.redhat.com/show_bug.cgi?id=1591732
If kernel is compiled without CONFIG_BLK_DEV_DM enabled, there is
no /dev/mapper/control device and since dm_task_create() actually
does some ioctl() over it creating a task may fail.
To cope with this handle ENOENT and ENODEV gracefully.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Just like in previous commit, qemu-pr-helper might want to open
/dev/mapper/control under certain circumstances. Therefore we
have to allow it in cgroups.
The change virdevmapper.c might look spurious but it isn't. After
6dd84f6850 any path that we're allowing in deivces CGroup is
subject to virDevMapperGetTargets() inspection. And libdevmapper
returns ENXIO for the path from subject.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>
This helper fetches dependencies for given device mapper target.
At the same time, we need to provide a dummy log function because
by default libdevmapper prints out error messages to stderr which
we need to suppress.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
