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authorZyad A. Ali <zyad.ali.me@gmail.com>2021-05-31 21:07:47 +0200
committerZyad A. Ali <zyad.ali.me@gmail.com>2021-07-13 22:12:02 +0200
commit7eae6402c111323cd6e92e0499dfa12cf2554d1a (patch)
tree8fc3aa361048a4f681764e929f8506c9fd10a68a /pkg/sentry/kernel/msgqueue
parent7c488fcfe8a5fd17f99f1c88c29ce97f5851f786 (diff)
Implement Registry.FindOrCreate.
FindOrCreate implements the behaviour of msgget(2). Updates #135
Diffstat (limited to 'pkg/sentry/kernel/msgqueue')
-rw-r--r--pkg/sentry/kernel/msgqueue/BUILD7
-rw-r--r--pkg/sentry/kernel/msgqueue/msgqueue.go93
2 files changed, 93 insertions, 7 deletions
diff --git a/pkg/sentry/kernel/msgqueue/BUILD b/pkg/sentry/kernel/msgqueue/BUILD
index dfe937e78..4114ee45a 100644
--- a/pkg/sentry/kernel/msgqueue/BUILD
+++ b/pkg/sentry/kernel/msgqueue/BUILD
@@ -23,10 +23,15 @@ go_library(
],
visibility = ["//pkg/sentry:internal"],
deps = [
+ "//pkg/abi/linux",
+ "//pkg/context",
+ "//pkg/errors/linuxerr",
+ "//pkg/log",
+ "//pkg/sentry/fs",
"//pkg/sentry/kernel/auth",
"//pkg/sentry/kernel/ipc",
"//pkg/sentry/kernel/time",
- "//pkg/waiter",
"//pkg/sync",
+ "//pkg/waiter",
],
)
diff --git a/pkg/sentry/kernel/msgqueue/msgqueue.go b/pkg/sentry/kernel/msgqueue/msgqueue.go
index 51db8b12c..0e2d996a8 100644
--- a/pkg/sentry/kernel/msgqueue/msgqueue.go
+++ b/pkg/sentry/kernel/msgqueue/msgqueue.go
@@ -16,14 +16,28 @@
package msgqueue
import (
- "sync"
-
+ "gvisor.dev/gvisor/pkg/abi/linux"
+ "gvisor.dev/gvisor/pkg/context"
+ "gvisor.dev/gvisor/pkg/errors/linuxerr"
+ "gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
"gvisor.dev/gvisor/pkg/sentry/kernel/ipc"
ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
+ "gvisor.dev/gvisor/pkg/sync"
"gvisor.dev/gvisor/pkg/waiter"
)
+const (
+ // System-wide limit for maximum number of queues.
+ maxQueues = linux.MSGMNI
+
+ // Maximum size of a queue in bytes.
+ maxQueueBytes = linux.MSGMNB
+
+ // Maximum size of a message in bytes.
+ maxMessageBytes = linux.MSGMAX
+)
+
// Registry contains a set of message queues that can be referenced using keys
// or IDs.
//
@@ -36,6 +50,13 @@ type Registry struct {
reg *ipc.Registry
}
+// NewRegistry returns a new Registry ready to be used.
+func NewRegistry(userNS *auth.UserNamespace) *Registry {
+ return &Registry{
+ reg: ipc.NewRegistry(userNS),
+ }
+}
+
// Queue represents a SysV message queue, described by sysvipc(7).
//
// +stateify savable
@@ -103,9 +124,69 @@ type Message struct {
mSize uint64
}
-// NewRegistry returns a new Registry ready to be used.
-func NewRegistry(userNS *auth.UserNamespace) *Registry {
- return &Registry{
- reg: ipc.NewRegistry(userNS),
+// FindOrCreate creates a new message queue or returns an existing one. See
+// msgget(2).
+func (r *Registry) FindOrCreate(ctx context.Context, key ipc.Key, mode linux.FileMode, private, create, exclusive bool) (*Queue, error) {
+ r.mu.Lock()
+ defer r.mu.Unlock()
+
+ if !private {
+ queue, err := r.reg.Find(ctx, key, mode, create, exclusive)
+ if err != nil {
+ return nil, err
+ }
+
+ if queue != nil {
+ return queue.(*Queue), nil
+ }
+ }
+
+ // Check system-wide limits.
+ if r.reg.ObjectCount() >= maxQueues {
+ return nil, linuxerr.ENOSPC
}
+
+ return r.newQueueLocked(ctx, key, fs.FileOwnerFromContext(ctx), fs.FilePermsFromMode(mode))
+}
+
+// newQueueLocked creates a new queue using the given fields. An error is
+// returned if there're no more available identifiers.
+//
+// Precondition: r.mu must be held.
+func (r *Registry) newQueueLocked(ctx context.Context, key ipc.Key, creator fs.FileOwner, perms fs.FilePermissions) (*Queue, error) {
+ q := &Queue{
+ registry: r,
+ obj: ipc.NewObject(r.reg.UserNS, key, creator, creator, perms),
+ sendTime: ktime.ZeroTime,
+ receiveTime: ktime.ZeroTime,
+ changeTime: ktime.NowFromContext(ctx),
+ maxBytes: maxQueueBytes,
+ }
+
+ err := r.reg.Register(q)
+ if err != nil {
+ return nil, err
+ }
+ return q, nil
+}
+
+// Lock implements ipc.Mechanism.Lock.
+func (q *Queue) Lock() {
+ q.mu.Lock()
+}
+
+// Unlock implements ipc.mechanism.Unlock.
+//
+// +checklocksignore
+func (q *Queue) Unlock() {
+ q.mu.Unlock()
+}
+
+// Object implements ipc.Mechanism.Object.
+func (q *Queue) Object() *ipc.Object {
+ return q.obj
+}
+
+// Destroy implements ipc.Mechanism.Destroy. It's yet to be implemented.
+func (q *Queue) Destroy() {
}