Now that we have app sets in the interfaces repo, keep a pointer to them in ConnectedPlug/Slot types. Use this to build label expressions in the interfaces.
* many: add a pointer to a SnapAppSet into Connected(Plug|Slot) to that interfaces can build a complete label expression, including component hooks
* interfaces: update doc comments on ConnectedPlug/Slot.AppSet
* interfaces: remove TODO that has been addressed
* interfaces: use app set pointer for instance name check
* snap: add Runnable type that represents the runnable parts of a snap
* interfaces, o/ifacestate: use snap.Runnable rather than interfaces.Runnable
* interfaces, i/builtin, o/ifacestate: panic on failed invariant check in NewConnectedPlug/Slot
* interfaces: add methods to app set for getting runnables that can connect to plug/slot
* interfaces: build label expressions using runnables
* interfaces: doc comment for SlotRunnables
* interfaces: implement Slot/PlugRunnables with shared helper
* interfaces: log and skip security tags that do not match expected pattern
* snap, interfaces: move runnable constructors to methods on AppInfo and HookInfo
* interfaces: refactor to allow labelExpr to operate directly on a ConnectedPlug/Slot
* snap: move around Runnable methods
* features,i/{apparmor,builtin}: include prompt prefix in home interface
If prompting is supported and enabled, include the prompt prefix in
AppArmor rules for the home interface, which will cause AppArmor to send
a prompt when accessing any file in $HOME.
In the future, if other interfaces include the ###PROMPT### prefix in
their rule snippets, this will also be handled accordingly.
At the moment, the status of prompting support is checked whenever the
AppArmor backend prepares profiles. This is okay, since AppArmor support
for prompting depends on kernel and parser features, which are only
probed once after snapd starts. However, to ensure that the same
supported value is used even if that were not the case, and in case we
wish to only use the prompt prefix for some snaps or interfaces, we may
wish to embed whether to use the prompt prefix in the AppArmor
Specification instead.
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* features: adjust unsupported messages when checking apparmor features errors
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* interfaces: add prompting status to system key
Include whether prompting is supported and enabled as a single field in
the system key. This way, if `(supported && enabled)` changes, security
profiles will be regenerated when snapd starts up.
Currently, prompting support only changes when the AppArmor kernel or
parser features change, and profile regeneration is the only other place
where it is checked whether AppArmor prompting is supported and enabled.
Thus, including whether prompting is supported and enabled in the system
key ensures that security profiles are regenerated when necessary during
snapd startup, and only when necessary (e.g. not if support changed but
prompting flag remained disabled nor if flag changed but prompting
remained unsupported).
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* o/c/configcore: restart snapd when prompting value changes
When the prompting flag changes and the result entails that security
profiles should be regenerated, restart snapd to do so.
This is required iff prompting is supported and the experimental
apparmor-prompting flag changes -- if prompting is not supported,
prompting can't be used, so no need to regenerate profiles. Importantly,
prompting support is based entirely on the available AppArmor kernel and
parser features, and these are only probed once during snapd startup, so
prompting support cannot change (under the current implementation)
except when snapd restarts.
Since `(supported && enabled)` is part of the system key, and a restart
is only triggered if prompting is supported and the flag value changes
(which is equivalent to `(supported && enabled)`, since the supported
value cannot change while snapd is running), restarting after the flag
has changed causes the system key to be different, and thus to trigger a
security profile regeneration, as desired.
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* interfaces,o/ifacestate: set prompting in apparmor spec
Rather than checking whether AppArmor prompting is supported and enabled
whenever the AppArmor backend is processing a snippet, instead include
that precomputed value in the Specification itself, and place it there
via `buildConfinementOptions`. This way, any spec created with the same
`confinementOptions` will make the same decision as to whether to
include prompt prefixes on relevant rules.
Currently, `buildConfinementOptions` simply checks whether prompting is
supported and enabled via the methods on `features.AppArmorPrompting`,
but ideally, this value would be looked up from either the system key
or by checking whether the prompting listener is running. It remains to
be seen how the value computed as part of the system key can be
guaranteed to be the same as that used elsewhere, either in
`buildConfinementOptions` or when deciding whether to start the
listener.
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* o/c/configcore: request snapd restart whenever prompting flag changes
Previously, a snapd restart was only requested when the status of the
"apparmor-prompting" experimental feature flag changed and prompting was
supported. However, since prompting support is dependent on AppArmor
kernel and parser features which are probed only once during startup,
and systems which do not use vendored AppArmor may have had an update to
the system AppArmor package which newly supports AppArmor prompting, it
is safer to request a restart of snapd to re-check for prompting
support.
This way, if one is enabling prompting for the first time on a system
without prompting support, they can have snapd installed, update their
kernel or apparmor installation to support prompting, and then set the
prompting flag to enable prompting without needing to manually restart
snapd.
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* interfaces: support optional trailing space after ###PROMPT###
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
i/apparmor: move promptReplacer definition to before its use
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* tests: add test of restart behavior when setting experimental.apparmor-prompting
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* tests: refactor prompting test to reset failed count and safely check for restarts
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
tests: add shellcheck exception for apparmor prompting flag restart test
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* tests: check that snapd PID != 0 and use snap changes to wait for feature change to complete
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* tests: check for start-limit-hit before calling reset-failed
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* tests: add ubuntu core to apparmor prompting flag restart test
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* tests: check apparmor-prompting value after setting it unchanged
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* Revert "tests: check for start-limit-hit before calling reset-failed"
This reverts commit bea68516c3287fa44d6718f0794484746ae99ac5.
* tests: check systemd start-limit-hit when apparmor-prompting flag changed
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* o/configstate/configcore: add unit tests for doExperimentalApparmorPromptingDaemonRestart
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* i/builtin: add missing prompt prefix and adjust test
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* i/apparmor: add test for prompt prefix substitution
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* many: pass prompting value into system key functions
As such, we now precompute whether prompting is supported and enabled in
`InterfaceManager.StartUp()`, store it in the `InterfaceManager`
instance, and pass it into the call to `WriteSystemKey()`.
Additionally, we make `buildConfinementOptions` a method of
`InterfaceManager`, thus eliminating the need to check within the system
key functions whether prompting is supported and enabled.
However, there remains a problem that `snap run` calls
`SystemKeyMismatch()`, which previously invoked
`apparmor.ParserFeatures()` via `AppArmorPrompting.IsSupported()`, and
now calls `AppArmorPrompting.IsSupported()` directly and passes the
result into `SystemKeyMismatch()`. In either case, we really want this
to be avoided if at all possible, since `snap run` does not have access
to the cached value from the `InterfaceManager`, and thus must invoke
the `apparmor_parser` binary to check parser features whenever we want
to run any snap.
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* many: don't probe parser features when checking system key mismatch
Since `snap run` calls `SystemKeyMismatch()`, we want to avoid needing
to call `AppArmorPrompting.IsSupported()` if at all possible, since this
calls `apparmor.ParserFeatures()`, which executes the `apparmor_parser`
binary. We can and should call `AppArmorPrompting.IsSupported()` when
writing the system key, but not when checking for a mismatch.
The system key written to disk should correctly hold the list of kernel
and parser features, the parser mtime, and whether or not prompting was
previously supported and enabled. We can check whether apparmor parser
features have changed by checking the parser mtime, without needing to
probe parser features -- this optimization is already used by
`SystemKeyMismatch()`. If we knew whether prompting was previously
supported (regardless of whether it was enabled), then so long as the
parser and kernel features are unchanged, we know that prompting support
is also unchanged.
Thus, if we add a second prompting-related field to the system key, this
one storing whether prompting is supported (ignoring enabled), we can
check if prompting support is unchanged without needing to call
`AppArmorPrompting.IsSupported()`.
Furthermore, `SystemKeyMismatch()` is the function in question, and if
there is any mismatch detected, it should return such as soon as
possible, regardless of what the mismatch is. Therefore, if we know that
either kernel or parser features have changed, then we can immediately
return that there is a mismatch, and we don't need to check whether
those feature changes affect prompting support.
Therefore, the new cases which we must worry about when checking for a
system key mismatch are the following, when all other system key fields
are unchanged (note that prompting must be supported in order to be
supported&&enabled):
1. supported: F, supported&&enabled: F, newFlag: F, mismatch: F
2. supported: F, supported&&enabled: F, newFlag: T, mismatch: F
3. supported: T, supported&&enabled: F, newFlag: F, mismatch: F
4. supported: T, supported&&enabled: F, newFlag: T, mismatch: T
5. supported: T, supported&&enabled: T, newFlag: F, mismatch: T
6. supported: T, supported&&enabled: T, newFlag: T, mismatch: F
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* interfaces: fix test string formatting
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* o/configstate/configcore: adjust prompting-related comments
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* tests: increase prompting check_snapd_restarted timeout and add systemd show
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* tests: reset start limit when checking if snapd restarted after prompting change
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* many: add system key extra data to hold prompting enabled status
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* many: only store one apparmor prompting value in system key
When checking for a system key mismatch, use the stored AppArmor
parser features from the system key on disk (along with the kernel
features from the newly-generated key) to check whether prompting is
supported, and AND that with the `AppArmorPrompting` value passed in
with the `SystemKeyExtraData`. If the kernel or parser features have
changed, the system key will be a mismatch anyway, so it is perfectly
safe to use the existing parser features to check for prompting support.
As such, the functions to check for prompting support have been moved
from `features` to `sandbox/apparmor`, and the support check has been
separated from the call to get `ParserFeatures()` and
`KernelFeatures()`, so that the values from the system key can be passed
in instead of invoking those functions.
Using the system key's stored parser and kernel features, there is no
need to save whether prompting is supported as part of the system key,
simplifying the key and the logic used to set the prompting value.
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* tests: explicitly install jq in apparmor-prompting-flag-restart test
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* many: consolidate checks for apparmor prompting support
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* interfaces,s/apparmor: use features struct when checking prompting support
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* tests: improve logging in apparmor-prompting-flag-restart test
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* tests: fix prompting flag restart test on core18
For some reason, when snapd fails due to start-limit-hit on core18, the
snapd.failure.service starts and acquires the state lock, thus
preventing snapd from successfully becoming "active" again and leaving
it retrying at "activating". It is unclear why this happens on core18
and not elsewhere.
As a fix, when resetting the start limit, stop snapd.failure.service
manually to ensure that snapd can successfully start.
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
---------
Signed-off-by: Oliver Calder <oliver.calder@canonical.com>
* interfaces: introduce SnapAppSet and forward one to the security backends
* snap: implement methods on snap.Info for getting apps and hooks for slots and plugs
This will enable us to remove the Hooks fields from the SlotInfo and
PlugInfo structs.
* interfaces: implement methods on SnapAppSet in terms of methods on snap.Info
* snap, interfaces: replace usage of {Plug,Slot}Info.SecurityTags with methods on SnapAppSet
* i/builtin: replace slotAppLabelExpr and plugAppLabelExpr with corresponding methods on SnapAppSet
* snap, o/snapstate, interfaces: remove Hooks field on snap.PlugInfo and snap.SlotInfo
* builtin, interfaces: fix tests that use Specification that now have a SnapAppSet
* snap: add tests for new methods on Info
* interfaces, i/builtin: port over some tests for SnapAppSet methods {Plug,Slot}LabelExpression
* interfaces: test PlugSecurityTags and SlotSecurityTags methods
* interfaces: add doc comments to SnapAppSet and methods
* i/builtin: remove ported over tests
* interfaces, many: require that SnapAppSet methods for getting security tags are called with plug/slot that comes from correct snap
Many tests did not properly adhere to this requirment, so they had to be
modifed to modify this rule.
Additionally, a hack was inroduced in the methods for getting label
expressions on the SnapAppSet. If a plug/slot did not originate from the
same snap that the SnapAppSet was created from, then we will use the
snap.Info that the plug/slot carries in the method instead. This will
fail to work once component hooks are introduced, so this will need to
be resolved by then.
* interfaces: test fallback for using LabelExpr methods with mismatch plug/slot
* snap: correct placement of TODOs to preserve doc comments
* snap: add doc comments for Plug/Slot.Unscoped
* interfaces: test for using SecurityTagsForPlug and SecurityTagsForSlot with wrong snap
* interfaces: tweak error messages in SnapAppSet SecurityTags methods
* i/builtin: fix missed conflict
* i/apparmor: add doc comment to Specification.appSet
* snap: fix doc coment on PlugInfo.Unscoped
Replace ioutil.WriteFile with os.WriteFile since the former has been
deprecated since go1.16 and simply calls the latter.
Signed-off-by: Miguel Pires <miguel.pires@canonical.com>
* DT-1021: discard namespace and retry if updateSnapNamespace fails
Recently, there was a change in the layout of the Steam snap:
some binds were replaced by symlinks. These changes are
currently in the --edge stream, while the --beta stream still
has the binds.
Unfortunately, trying to update from the beta version to the
edge one fails with these errors:
raster ~$ sudo snap refresh --edge steam
error: cannot perform the following tasks:
- Configurar los perfiles de seguridad del snap "steam" (112) (cannot update mount namespace of snap "steam": cannot update preserved namespace of snap "steam": cannot update snap namespace: cannot create symlink in "/usr/lib/i386-linux-gnu/libvulkan_intel.so": existing file in the way)
raster ~$ sudo snap refresh --edge steam
error: cannot perform the following tasks:
- Configurar los perfiles de seguridad del snap "steam" (112) (cannot update mount namespace of snap "steam": cannot update preserved namespace of snap "steam":
change.go:471: cannot remove mount point, got EBUSY: "/snap/steam/83"
cannot update snap namespace: cannot create symlink in "/usr/lib/i386-linux-gnu/libvulkan_intel.so": existing file in the way
raster ~$ sudo snap refresh --edge steam
error: cannot perform the following tasks:
- Configurar los perfiles de seguridad del snap "steam" (112) (cannot update mount namespace of snap "steam": cannot update preserved namespace of snap "steam":
change.go:471: cannot remove mount point, got EBUSY: "/snap/steam/83"
cannot update snap namespace: cannot create symlink in "/usr/lib/i386-linux-gnu/libvulkan_intel.so": existing file in the way
Manually executing
"/snap/snapd/current/usr/lib/snapd/snap-discard-ns steam"
fixes the problem and allows to successfully update the snap.
This patch automagically executes the command if the update
fails while updating the snap's namespace, and then retries
the operation. With it, the steam update work flawlessly.
Fix https://github.com/canonical/steam-snap/issues/111
* Don't try to refresh if the refresh mode is "endure"
* i/mount: cleanup and simplify discard on failing update logic, fix tests
* Update interfaces/mount/backend.go
Co-authored-by: Philip Meulengracht <the_meulengracht@hotmail.com>
* Added comment explaining why this is being done.
* Fix nitpicks
* Fix test
* Add "endure" mode to the daemon test snaps
---------
Co-authored-by: Samuele Pedroni <pedronis@lucediurna.net>
Co-authored-by: Philip Meulengracht <the_meulengracht@hotmail.com>
Go 1.19 includes some changes to gofmt which intend to make lists and
heading clearer when rendered (https://go.dev/doc/go1.19). This commit
is the result of running the new gofmt and manually fixing some of it.
This was necessary because the new gofmt assumed lines beginning w/ tabs
to start lists or examples. While this is often true in our codebase,
we occasionally also use tabs to indent the lines after a TODO or FIXME
prefix or in yaml (e.g., excerpts of a snap.yaml). This meant that a lot of the
reformatted comments were broken and had to be fixed manually.
Signed-off-by: Miguel Pires <miguel.pires@canonical.com>
* i/mount: merge clashing mount entries, when possible
In the case when two interfaces (or an interface and a layout) request
the same mount entry to be setup, where "same" means having the same
target, source, and FS type, let's resolve the clash by merging the two
entries into a single one.
As for the mount options, these are merged taking into account that the
snap will need to get the "union" of the permissions granted by the
merged entries: so, the resulting entry will be read/write if at least
one of the requested entries is read/write, and "rbind" will win over
"bind".
We previously wouldn't fail on verification for snaps that used new top-level
directories, and would fail at runtime, which produces a very unhelpful message.
Also adjust some test yamls in interfaces/mount tests, which are not valid as
they are for new top-level directories in /.
Finally, add an additional unit test for the test case with LP #1831010 that is
already covered by spread tests, but not yet by unit tests.
Signed-off-by: Ian Johnson <ian.johnson@canonical.com>
Take into account the host's cgroup version when reporting mount backend
features.
Signed-off-by: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>
The directory synchronization code grew out of the desire to have a set
of files described by a glob and short, in-memory contents be reflected
to the disk in an efficient and predictable way.
Recently this code has started to be used to install icon themes shipped
by snaps. This means it may be used to coerce snapd to read arbitrary
amount of data into memory.
This address this issue by generalizing the directory sync APIs to take
an interface instead of a concrete representation of the desired file.
There are now three concrete implementations, one that keeps the content
in memory, just like before, called MemoryBlob and two new ones:
FileReference and FileContentReference. Those both refer to an existing
file for content, opening up the possibility to refer to large files.
They only differ in the treatment of file mode, either mirroring the
mode of the file being referred or using a fixed mode, respectively.
Behind the scenes the EnsureFileState function will no longer read all
of the file into memory. Instead if will use FileReference to stream it,
chunk by chunk, in an attempt to see if the file is identical to what we
expected.
On top of that, if the file is not the same and the caller has provided
a FileReference or FileContentReference, the logic that writes a new
file and replaces the original is also using streaming, again saving a
in-memory copy.
This way we can now process files of arbitrary size using fixed amount
of memory. This involves the new icon wrapper which has been switched to
use FileContentReference.
The patch contains some verbose automatic changes around the code using
maps of FileState structure to replace them with maps of FileState
interface instead.
Signed-off-by: Zygmunt Krynicki <me@zygoon.pl>
When a snap is removed each security backend is asked to remove the
security profiles associated with the snap in question. For the mount
backend that would just remove the desired mount namespace profile.
While this part worked correctly there was more to be done. The system
may still have the preserved mount namespace as well as the actual
applied (current) mount profiles that exist therein.
In a case where a snap was installed but the installation failed because
of a hook issue, the system would be left in a state where an existing
mount namespace would be left behind.
Related-To: https://bugs.launchpad.net/snapd/+bug/1808821
Signed-off-by: Zygmunt Krynicki <me@zygoon.pl>
