When running unprivileged, virSetUIDGIDWithCaps will fail because it
tries to add the requested capabilities to the permitted and effective
sets.
Detect this case, and invoke the child with cleared permitted and
effective sets. If it is a setuid program, it will get them.
Some care is needed also because you cannot drop capabilities from the
bounding set without CAP_SETPCAP. Because of that, ignore errors from
setting the bounding set.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The need_prctl variable is not really needed. If it is false,
capng_apply will be called twice with the same set, causing
a little extra work but no problem. This keeps the code a bit
simpler.
It is also clearer to invoke capng_apply(CAPNG_SELECT_BOUNDS)
separately, to make sure it is done while we have CAP_SETPCAP.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The recent qemu requires "0x" prefix for the disk wwn, this patch
changes virValidateWWN to allow the prefix, and prepend "0x" if
it's not specified. E.g.
qemu-kvm: -device scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,lun=0,\
drive=drive-scsi0-0-0-0,id=scsi0-0-0-0,wwn=6000c60016ea71ad:
Property 'scsi-hd.wwn' doesn't take value '6000c60016ea71ad'
Though it's a qemu regression, but it's nice to allow the prefix,
and doesn't hurt for us to always output "0x".
This finds the parent for vHBA by iterating over all the HBA
which supports vport_ops capability on the host, and return
the first one which is online, not saturated (vports in use
is less than max_vports).
The helper iterates over sysfs, to find out the matched scsi host
name by comparing the wwnn,wwpn pair. It will be used by checkPool
and refreshPool of storage scsi backend. New helper getAdapterName
is introduced in storage_backend_scsi.c, which uses the new util
helper virGetFCHostNameByWWN to get the fc_host adapter name.
This abstracts nodeDeviceVportCreateDelete as an util function
virManageVport, which can be further used by later storage patches
(to support persistent vHBA, I don't want to create the vHBA
using the public API, which is not good).
This adds two util functions (virIsCapableFCHost and virIsCapableVport),
and rename helper check_fc_host_linux as detect_scsi_host_caps,
check_capable_vport_linux is removed, as it's abstracted to the util
function virIsCapableVport. detect_scsi_host_caps nows detect both
the fc_host and vport_ops capabilities. "stat(2)" is replaced with
"access(2)" for saving.
* src/util/virutil.h:
- Declare virIsCapableFCHost and virIsCapableVport
* src/util/virutil.c:
- Implement virIsCapableFCHost and virIsCapableVport
* src/node_device/node_device_linux_sysfs.c:
- Remove check_capable_vport_linux
- Rename check_fc_host_linux as detect_scsi_host_caps, and refactor
it a bit to detect both fc_host and vport_os capabilities
* src/node_device/node_device_driver.h:
- Change/remove the related declarations
* src/node_device/node_device_udev.c: (Use detect_scsi_host_caps)
* src/node_device/node_device_hal.c: (Likewise)
* src/node_device/node_device_driver.c (Likewise)
"open_wwn_file" in node_device_linux_sysfs.c is redundant, on one
hand it duplicates work of virFileReadAll, on the other hand, it's
waste to use a function for it, as there is no other users of it.
So I don't see why the file opening work cannot be done in
"read_wwn_linux".
"read_wwn_linux" can be abstracted as an util function. As what all
it does is to read the sysfs entry.
So this patch removes "open_wwn_file", and abstract "read_wwn_linux"
as an util function "virReadFCHost" (a more general name, because
after changes, it can read each of the fc_host entry now).
* src/util/virutil.h: (Declare virReadFCHost)
* src/util/virutil.c: (Implement virReadFCHost)
* src/node_device/node_device_linux_sysfs.c: (Remove open_wwn_file,
and read_wwn_linux)
src/node_device/node_device_driver.h: (Remove the declaration of
read_wwn_linux, and the related macros)
src/libvirt_private.syms: (Export virReadFCHost)
We've already scrubbed for comparisons of 'uid_t == -1' (which fail
on platforms where uid_t is a u16), but another one snuck in.
* src/util/virutil.c (virSetUIDGIDWithCaps): Correct uid comparison.
* cfg.mk (sc_prohibit_risky_id_promotion): New rule.
My commit 7a2e845a86 (and its
prerequisites) managed to effectively ignore the
clear_emulator_capabilities setting in qemu.conf (visible in the code
as the VIR_EXEC_CLEAR_CAPS flag when qemu is being exec'ed), with the
result that the capabilities are always cleared regardless of the
qemu.conf setting. This patch fixes it by passing the flag through to
virSetUIDGIDWithCaps(), which uses it to decide whether or not to
clear existing capabilities before adding in those that were
requested.
Note that the existing capabilities are *always* cleared if the new
process is going to run as non-root, since the whole point of running
non-root is to have the capabilities removed (it's still possible to
maintain individual capabilities as needed using the capBits argument
though).
A value which is equal to a integer maximum such as LLONG_MAX is
a valid integer value.
The patch fix the following error:
1, virsh memtune vm --swap-hard-limit -1
2, virsh start vm
In debug mode, it shows error like:
virScaleInteger:1813 : numerical overflow:\
value too large: 9007199254740991KiB
uid_t and gid_t are opaque types, ranging from s32 to u32 to u64.
Explicitly cast the magic -1 to the appropriate type.
Signed-off-by: Philipp Hahn <hahn@univention.de>
The uid_t|gid_t values are explicitly casted to "unsigned long", but the
printf() still used "%d", which is for signed values.
Change the format to "%u".
Signed-off-by: Philipp Hahn <hahn@univention.de>
Normally when a process' uid is changed to non-0, all the capabilities
bits are cleared, even those explicitly set with calls to
capng_update()/capng_apply() made immediately before setuid. And
*after* the process' uid has been changed, it no longer has the
necessary privileges to add capabilities back to the process.
In order to set a non-0 uid while still maintaining any capabilities
bits, it is necessary to either call capng_change_id() (which
unfortunately doesn't currently call initgroups to setup auxiliary
group membership), or to perform the small amount of calisthenics
contained in the new utility function virSetUIDGIDWithCaps().
Another very important difference between the capabilities
setting/clearing in virSetUIDGIDWithCaps() and virCommand's
virSetCapabilities() (which it will replace in the next patch) is that
the new function properly clears the capabilities bounding set, so it
will not be possible for a child process to set any new
capabilities.
A short description of what is done by virSetUIDGIDWithCaps():
1) clear all capabilities then set all those desired by the caller (in
capBits) plus CAP_SETGID, CAP_SETUID, and CAP_SETPCAP (which is needed
to change the capabilities bounding set).
2) call prctl(), telling it that we want to maintain current
capabilities across an upcoming setuid().
3) switch to the new uid/gid
4) again call prctl(), telling it we will no longer want capabilities
maintained if this process does another setuid().
5) clear the capabilities that we added to allow us to
setuid/setgid/change the bounding set (unless they were also requested
by the caller via the virCommand API).
Because the modification/maintaining of capabilities is intermingled
with setting the uid, this is necessarily done in a single function,
rather than having two independent functions.
Note that, due to the way that effective capabilities are computed (at
time of execve) for a process that has uid != 0, the *file*
capabilities of the binary being executed must also have the desired
capabilities bit(s) set (see "man 7 capabilities"). This can be done
with the "filecap" command. (e.g. "filecap /usr/bin/qemu-kvm sys_rawio").
Rather than treating uid:gid of 0:0 as a NOP, we blindly pass that
through to the lower layers. However, we *do* check for a requested
value of "-1" to mean "don't change this setting". setregid() and
setreuid() already interpret -1 as a NOP, so this is just an
optimization, but we are also calling getpwuid_r and initgroups, and
it's unclear what the former would do with a uid of -1.
Currently, whenever somebody calls saferead() on nonblocking FD
(safewrite() is totally interchangeable for purpose of this message)
he might get wrong return value. For instance, in the first iteration
some data is read. The number of bytes read is stored into local
variable 'nread'. However, in next iterations we can get -1 from
read() with errno == EAGAIN, in which case the -1 is returned despite
fact some data has already been read. So the caller gets confused.
Bare read() should be used for nonblocking FD.
There's no need to do lots of readlink() calls to canonicalize
a name if we're only going to use stat() on it, since stat()
already chases symlinks.
* src/util/virutil.c (virGetDeviceID): Let stat() do the symlink
chasing.
"virGetDeviceID" could be used across the sources, but it doesn't
relate with this series, and could be done later.
* src/util/virutil.h: (Declare virGetDeviceID, and
vir{Get,Set}DeviceUnprivSGIO)
* src/util/virutil.c: (Implement virGetDeviceID and
vir{Get,Set}DeviceUnprivSGIO)
* src/libvirt_private.syms: Export private symbols of upper helpers
