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2019-04-02filemon: fix watch IDs to avoid potential wraparound issuesDaniel P. Berrangé
Watch IDs are allocated from incrementing a int counter against the QFileMonitor object. In very long life QEMU processes with a huge amount of USB MTP activity creating & deleting directories it is just about conceivable that the int counter can wrap around. This would result in incorrect behaviour of the file monitor watch APIs due to clashing watch IDs. Instead of trying to detect this situation, this patch changes the way watch IDs are allocated. It is turned into an int64_t variable where the high 32 bits are set from the underlying inotify "int" ID. This gives an ID that is guaranteed unique for the directory as a whole, and we can rely on the kernel to enforce this. QFileMonitor then sets the low 32 bits from a per-directory counter. The USB MTP device only sets watches on the directory as a whole, not files within, so there is no risk of guest triggered wrap around on the low 32 bits. Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
2019-03-22trace-events: Fix attribution of trace points to sourceMarkus Armbruster
Some trace points are attributed to the wrong source file. Happens when we neglect to update trace-events for code motion, or add events in the wrong place, or misspell the file name. Clean up with help of cleanup-trace-events.pl. Same funnies as in the previous commit, of course. Manually shorten its change to linux-user/trace-events to */signal.c. Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-id: 20190314180929.27722-6-armbru@redhat.com Message-Id: <20190314180929.27722-6-armbru@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2019-03-22trace-events: Shorten file names in commentsMarkus Armbruster
We spell out sub/dir/ in sub/dir/trace-events' comments pointing to source files. That's because when trace-events got split up, the comments were moved verbatim. Delete the sub/dir/ part from these comments. Gets rid of several misspellings. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Message-id: 20190314180929.27722-3-armbru@redhat.com Message-Id: <20190314180929.27722-3-armbru@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2019-02-26authz: add QAuthZPAM object type for authorizing using PAMDaniel P. Berrange
Add an authorization backend that talks to PAM to check whether the user identity is allowed. This only uses the PAM account validation facility, which is essentially just a check to see if the provided username is permitted access. It doesn't use the authentication or session parts of PAM, since that's dealt with by the relevant part of QEMU (eg VNC server). Consider starting QEMU with a VNC server and telling it to use TLS with x509 client certificates and configuring it to use an PAM to validate the x509 distinguished name. In this example we're telling it to use PAM for the QAuthZ impl with a service name of "qemu-vnc" $ qemu-system-x86_64 \ -object tls-creds-x509,id=tls0,dir=/home/berrange/security/qemutls,\ endpoint=server,verify-peer=yes \ -object authz-pam,id=authz0,service=qemu-vnc \ -vnc :1,tls-creds=tls0,tls-authz=authz0 This requires an /etc/pam/qemu-vnc file to be created with the auth rules. A very simple file based whitelist can be setup using $ cat > /etc/pam/qemu-vnc <<EOF account requisite pam_listfile.so item=user sense=allow file=/etc/qemu/vnc.allow EOF The /etc/qemu/vnc.allow file simply contains one username per line. Any username not in the file is denied. The usernames in this example are the x509 distinguished name from the client's x509 cert. $ cat > /etc/qemu/vnc.allow <<EOF CN=laptop.berrange.com,O=Berrange Home,L=London,ST=London,C=GB EOF More interesting would be to configure PAM to use an LDAP backend, so that the QEMU authorization check data can be centralized instead of requiring each compute host to have file maintained. The main limitation with this PAM module is that the rules apply to all QEMU instances on the host. Setting up different rules per VM, would require creating a separate PAM service name & config file for every guest. An alternative approach for the future might be to not pass in the plain username to PAM, but instead combine the VM name or UUID with the username. This requires further consideration though. Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2019-02-26authz: add QAuthZListFile object type for a file access control listDaniel P. Berrangé
Add a QAuthZListFile object type that implements the QAuthZ interface. This built-in implementation is a proxy around the QAuthZList object type, initializing it from an external file, and optionally, automatically reloading it whenever it changes. To create an instance of this object via the QMP monitor, the syntax used would be: { "execute": "object-add", "arguments": { "qom-type": "authz-list-file", "id": "authz0", "props": { "filename": "/etc/qemu/vnc.acl", "refresh": true } } } If "refresh" is "yes", inotify is used to monitor the file, automatically reloading changes. If an error occurs during reloading, all authorizations will fail until the file is next successfully loaded. The /etc/qemu/vnc.acl file would contain a JSON representation of a QAuthZList object { "rules": [ { "match": "fred", "policy": "allow", "format": "exact" }, { "match": "bob", "policy": "allow", "format": "exact" }, { "match": "danb", "policy": "deny", "format": "glob" }, { "match": "dan*", "policy": "allow", "format": "exact" }, ], "policy": "deny" } This sets up an authorization rule that allows 'fred', 'bob' and anyone whose name starts with 'dan', except for 'danb'. Everyone unmatched is denied. The object can be loaded on the comand line using -object authz-list-file,id=authz0,filename=/etc/qemu/vnc.acl,refresh=yes Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
2019-02-26authz: add QAuthZList object type for an access control listDaniel P. Berrange
Add a QAuthZList object type that implements the QAuthZ interface. This built-in implementation maintains a trivial access control list with a sequence of match rules and a final default policy. This replicates the functionality currently provided by the qemu_acl module. To create an instance of this object via the QMP monitor, the syntax used would be: { "execute": "object-add", "arguments": { "qom-type": "authz-list", "id": "authz0", "props": { "rules": [ { "match": "fred", "policy": "allow", "format": "exact" }, { "match": "bob", "policy": "allow", "format": "exact" }, { "match": "danb", "policy": "deny", "format": "glob" }, { "match": "dan*", "policy": "allow", "format": "exact" }, ], "policy": "deny" } } } This sets up an authorization rule that allows 'fred', 'bob' and anyone whose name starts with 'dan', except for 'danb'. Everyone unmatched is denied. It is not currently possible to create this via -object, since there is no syntax supported to specify non-scalar properties for objects. This is likely to be addressed by later support for using JSON with -object, or an equivalent approach. In any case the future "authz-listfile" object can be used from the CLI and is likely a better choice, as it allows the ACL to be refreshed automatically on change. Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2019-02-26authz: add QAuthZSimple object type for easy whitelist auth checksDaniel P. Berrangé
In many cases a single VM will just need to whitelist a single identity as the allowed user of network services. This is especially the case for TLS live migration (optionally with NBD storage) where we just need to whitelist the x509 certificate distinguished name of the source QEMU host. Via QMP this can be configured with: { "execute": "object-add", "arguments": { "qom-type": "authz-simple", "id": "authz0", "props": { "identity": "fred" } } } Or via the command line -object authz-simple,id=authz0,identity=fred Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2019-02-26authz: add QAuthZ object as an authorization base classDaniel P. Berrange
The current qemu_acl module provides a simple access control list facility inside QEMU, which is used via a set of monitor commands acl_show, acl_policy, acl_add, acl_remove & acl_reset. Note there is no ability to create ACLs - the network services (eg VNC server) were expected to create ACLs that they want to check. There is also no way to define ACLs on the command line, nor potentially integrate with external authorization systems like polkit, pam, ldap lookup, etc. The QAuthZ object defines a minimal abstract QOM class that can be subclassed for creating different authorization providers. Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>