fallback_exception_handler feeds a string with embedded newlines directly into
syslog(). While this is an improvement on getting nothing, syslogd escapes
all control characters it gets, and emits one (long) log line.
Fix the problem generally in the syslog stub. As we already have a local copy
of the string, split it in place and emit one syslog() call per line.
Also tweak Logging.msg_of to avoid putting an extra newline on a string which
already ends with one.
Fixes: ee7815f49f ("tools/oxenstored: Set uncaught exception handler")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Christian Lindig <christian.lindig@citrix.com>
(cherry picked from commit d2162d884c)
Unhandled exceptions go to stderr by default, but this doesn't typically work
for oxenstored because:
* daemonize reopens stderr as /dev/null
* systemd redirects stderr to /dev/null too
Debugging an unhandled exception requires reproducing the issue locally when
using --no-fork, and is not conducive to figuring out what went wrong on a
remote system.
Install a custom handler which also tries to render the backtrace to the
configured syslog facility, and DAEMON|ERR otherwise.
Signed-off-by: Edwin Török <edvin.torok@citrix.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Christian Lindig <christian.lindig@citrix.com>
(cherry picked from commit ee7815f49f)
Today watch events are sent regardless of the access rights of the
node the event is sent for. This enables any guest to e.g. setup a
watch for "/" in order to have a detailed record of all Xenstore
modifications.
Modify that by sending only watch events for nodes that the watcher
has a chance to see otherwise (either via direct reads or by querying
the children of a node). This includes cases where the visibility of
a node for a watcher is changing (permissions being removed).
Permissions for nodes are looked up either in the old (pre
transaction/command) or current trees (post transaction). If
permissions are changed multiple times in a transaction only the final
version is checked, because considering a transaction atomic the
individual permission changes would not be noticable to an outside
observer.
Two trees are only needed for set_perms: here we can either notice the
node disappearing (if we loose permission), appearing
(if we gain permission), or changing (if we preserve permission).
RM needs to only look at the old tree: in the new tree the node would be
gone, or could have different permissions if it was recreated (the
recreation would get its own watch fired).
Inside a tree we lookup the watch path's parent, and then the watch path
child itself. This gets us 4 sets of permissions in worst case, and if
either of these allows a watch, then we permit it to fire. The
permission lookups are done without logging the failures, otherwise we'd
get confusing errors about permission denied for some paths, but a watch
still firing. The actual result is logged in xenstored-access log:
'w event ...' as usual if watch was fired
'w notfired...' if the watch was not fired, together with path and
permission set to help in troubleshooting
Adding a watch bypasses permission checks and always fires the watch
once immediately. This is consistent with the specification, and no
information is gained (the watch is fired both if the path exists or
doesn't, and both if you have or don't have access, i.e. it reflects the
path a domain gave it back to that domain).
There are some semantic changes here:
* Write+rm in a single transaction of the same path is unobservable
now via watches: both before and after a transaction the path
doesn't exist, thus both tree lookups come up with the empty
permission set, and noone, not even Dom0 can see this. This is
consistent with transaction atomicity though.
* Similar to above if we temporarily grant and then revoke permission
on a path any watches fired inbetween are ignored as well
* There is a new log event (w notfired) which shows the permission set
of the path, and the path.
* Watches on paths that a domain doesn't have access to are now not
seen, which is the purpose of the security fix.
This is part of XSA-115.
Signed-off-by: Edwin Török <edvin.torok@citrix.com>
Acked-by: Christian Lindig <christian.lindig@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
This commit cleans up code to reduce compiler warnings:
* remove unused open statements (warning 33)
* remove unused 'rec' declarations (warnign 39)
* remove unused type declarations (warning 34)
* mark unused variables with an underscore (warning 27)
* mark unused value declarations with an underscore (warning 32)
This commit does not include changes to fix compiler warnings 52
(matching against strings in exceptions). These changes have no impact
on functionality.
Signed-off-by: Christian Lindig <christian.lindig@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
The rationalisation of the Xs_ring interface in the xb library
allows to further reduce the unsafe calls withouth introducing
copies. This patch also contains some further code cleanups.
Signed-off-by: Marcello Seri <marcello.seri@citrix.com>
Acked-by: Christian Lindig <christian.lindig@citrix.com>
Tested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Release-acked-by: Juergen Gross <jgross@suse.com>
When xenstore was ported to the new safe-string interface, it mostly
happened by making copyies of string into bytes and back. The ideal
fix would be to rewrite all of the relevant interfaces to be uniformly
using bytes, but in the meanwhile we can improve the code by using unsafe
conversion functions (see
https://caml.inria.fr/pub/docs/manual-ocaml/libref/Bytes.html#3_Unsafeconversionsforadvancedusers).
In most cases we own the bytes that we are converting to string, or we
immediately make copies that we then mutate, or we use them immutably
as payloads for writes. In all these cases it is safe to use the unsafe
functions and prevent a copy.
This patch updates the code to use the unsafe conversions where possible.
Signed-off-by: Marcello Seri <marcello.seri@citrix.com>
Reviewed-by: Christian Lindig <christian.lindig@citrix.com>
Release-acked-by: Juergen Gross <jgross@suse.com>
Xen built with ocaml 4.06 gives errors such as
Error: This expression has type bytes but an expression was
expected of type string
as Byte and safe-strings which were introduced in 4.02 are the
default in 4.06.
This patch which is partly by Richard W.M. Jones of Red Hat
from https://bugzilla.redhat.com/show_bug.cgi?id=1526703
fixes these issues.
Signed-off-by: Michael Young <m.a.young@durham.ac.uk>
Reviewed-by: Christian Lindig<christian.lindig@citrix.com>
Xen built with ocaml 4.06 gives errors such as
Error: This expression has type bytes but an expression was
expected of type string
as Byte and safe-strings which were introduced in 4.02 are the
default in 4.06.
This patch which is mostly by Richard W.M. Jones of Red Hat
from https://bugzilla.redhat.com/show_bug.cgi?id=1526703
fixes these issues.
v2: drop tools/ocaml/libs/xc/xenctrl.ml from the patch as the
affected code was removed by commit d933f1a53c
tools/ocaml: Drop coredump infrastructure
Signed-off-by: Michael Young <m.a.young@durham.ac.uk>
Reviewed-by: Christian Lindig <christian.lindig@citrix.com>
[ wei: remove trailing whitespaces ]
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
XS_RESTRICT and the xenstore library function xs_restrict() have never
been usable in all configurations and there are no known users.
This functionality was thought to limit access rights of device models
to xenstore in order to avoid affecting other domains in case of a
security breech. Unfortunately XS_RESTRICT won't help as current
qemu is requiring access to dom0 only accessible xenstore paths to
work correctly. So this command is useless and should be removed.
In order to avoid problems in the future remove all support for
XS_RESTRICT from xenstore.
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: David Scott <dave@recoil.org>
We generate a corresponding constant (in lower case) in paths.ml. Use
that in source code to get rid of hard-coded path.
Note that with this patch the default location for xenstored*.log is
changed from /var/log to /var/log/xen.
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: David Scott <dave@recoil.org>
We noticed that, if configured to use syslog as the logging backend, every
single line of access logging (via the syslog C binding) will call stat on
/etc/localtime for 3 times. The rational behind this is probably to detect any
timezone changes over time.
This is a considerable cost we'd like to avoid, given the intensiveness of our
access logging --- we log almost every xenstore status change (for good
reason). Also a running Xen host is rarely a mobile environment, so the little
benefit can hardly justify the cost.
Setting up the TZ environment varialbe can avoid stat calls.
Signed-off-by: Zheng Li <dev@zheng.li>
Reviewed-by: David Scott <dave.scott@citrix.com>
We now log different kinds of events at different levels. The convention
is now:
new/end_connection: Debug
coalesce: Debug
conflict: Debug
commit: Debug
regular ops: Info
start/end_transaction: Debug
error (ENOENT): Debug
error (any other): Warn
watch: Info
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
To log to files the config file should contain:
xenstored-log-file = /var/log/xenstored.log
access-log-file = /var/log/xenstored-access.log
(These two files are still the built-in defaults. The log format is
unchanged.)
To log to syslog the config file should contain:
xenstored-log-file = syslog:<facility>
access-log-file = syslog:<facility>
where <facility> is the syslog facility to use (e.g. 'daemon' 'local2')
Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Otherwise at the default level we rarely log anything at all.
A completely empty log file is a good sign, but only if you know you are
looking in the right place...
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
Previous an unknown operation would be decoded as a Not_found exception which
would bubble all the way up to the try ... with surrounding the call to
main_loop where it would be logged and ignored.
This would leave the guest hanging waiting for a response to the invalid
request.
Instead introduce a specific "Invalid" operation. Higher level functionality,
such as Process.process_packet, already handles operations which are not
understood with an error reply due to the final wildcard entry in
Process.function_of_type but explicitly handle Invalid this way to make it
clear what is going on.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson.citrix.com>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
The only user was oxenstored, which has had the relevant bits
merged in.
Signed-off-by: Zheng Li <zheng.li@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell.com>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
Acked-by: Jon Ludlam <jonathan.ludlam@eu.citrix.com>
ocamlfind does not support namespaces, so to avoid
name clashes the module names have become longer.
Additionally, the xenstore and xenbus subdirs, which
contain several modules each, have been packed into
toplevel Xenstore and Xenbus modules.
xb becomes xenbus, xc becomes xenctrl, xl becomes xenlight,
xs becomes xenstore, eventchn becomes xeneventchn and
mmap becomes xenmmap.
[ Patch modified from that submitted, to update the .hgignore, and to
cope with intervening changes to mmap_stubs.c -iwj ]
Signed-off-by: Jon Ludlam <jonathan.ludlam@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
Andrew Cooper
Edwin Török
Christian Lindig
Marcello Seri
Michael Young
Wei Liu
Juergen Gross
Zheng Li
David Scott
Ian Campbell
Jon Ludlam
Keir Fraser