diff options
Diffstat (limited to 'pkg/sentry/kernel/semaphore')
| -rw-r--r-- | pkg/sentry/kernel/semaphore/BUILD | 12 | ||||
| -rw-r--r-- | pkg/sentry/kernel/semaphore/semaphore.go | 172 | ||||
| -rw-r--r-- | pkg/sentry/kernel/semaphore/semaphore_test.go | 5 |
3 files changed, 84 insertions, 105 deletions
diff --git a/pkg/sentry/kernel/semaphore/BUILD b/pkg/sentry/kernel/semaphore/BUILD index 5dd607953..2ae08ed12 100644 --- a/pkg/sentry/kernel/semaphore/BUILD +++ b/pkg/sentry/kernel/semaphore/BUILD @@ -26,7 +26,6 @@ go_library( "//pkg/abi/linux", "//pkg/context", "//pkg/errors/linuxerr", - "//pkg/log", "//pkg/sentry/fs", "//pkg/sentry/kernel/auth", "//pkg/sentry/kernel/ipc", @@ -42,10 +41,11 @@ go_test( srcs = ["semaphore_test.go"], library = ":semaphore", deps = [ - "//pkg/abi/linux", - "//pkg/context", - "//pkg/sentry/contexttest", - "//pkg/sentry/kernel/auth", - "//pkg/syserror", + "//pkg/abi/linux", # keep + "//pkg/context", # keep + "//pkg/sentry/contexttest", # keep + "//pkg/sentry/kernel/auth", # keep + "//pkg/sentry/kernel/ipc", # keep + "//pkg/syserror", # keep ], ) diff --git a/pkg/sentry/kernel/semaphore/semaphore.go b/pkg/sentry/kernel/semaphore/semaphore.go index d609d88e2..b7879d284 100644 --- a/pkg/sentry/kernel/semaphore/semaphore.go +++ b/pkg/sentry/kernel/semaphore/semaphore.go @@ -21,7 +21,6 @@ import ( "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/errors/linuxerr" - "gvisor.dev/gvisor/pkg/log" "gvisor.dev/gvisor/pkg/sentry/fs" "gvisor.dev/gvisor/pkg/sentry/kernel/auth" "gvisor.dev/gvisor/pkg/sentry/kernel/ipc" @@ -48,12 +47,12 @@ const ( // // +stateify savable type Registry struct { - // userNS owning the ipc name this registry belongs to. Immutable. - userNS *auth.UserNamespace // mu protects all fields below. - mu sync.Mutex `state:"nosave"` - semaphores map[ipc.ID]*Set - lastIDUsed ipc.ID + mu sync.Mutex `state:"nosave"` + + // reg defines basic fields and operations needed for all SysV registries. + reg *ipc.Registry + // indexes maintains a mapping between a set's index in virtual array and // its identifier. indexes map[int32]ipc.ID @@ -69,7 +68,6 @@ type Set struct { // mu protects all fields below. mu sync.Mutex `state:"nosave"` - // obj defines basic fields that should be included in all SysV IPC objects. obj *ipc.Object opTime ktime.Time @@ -109,9 +107,8 @@ type waiter struct { // NewRegistry creates a new semaphore set registry. func NewRegistry(userNS *auth.UserNamespace) *Registry { return &Registry{ - userNS: userNS, - semaphores: make(map[ipc.ID]*Set), - indexes: make(map[int32]ipc.ID), + reg: ipc.NewRegistry(userNS), + indexes: make(map[int32]ipc.ID), } } @@ -129,31 +126,19 @@ func (r *Registry) FindOrCreate(ctx context.Context, key ipc.Key, nsems int32, m defer r.mu.Unlock() if !private { - // Look up an existing semaphore. - if set := r.findByKey(key); set != nil { - set.mu.Lock() - defer set.mu.Unlock() - - // Check that caller can access semaphore set. - creds := auth.CredentialsFromContext(ctx) - if !set.obj.CheckPermissions(creds, fs.PermsFromMode(mode)) { - return nil, linuxerr.EACCES - } + set, err := r.reg.Find(ctx, key, mode, create, exclusive) + if err != nil { + return nil, err + } - // Validate parameters. + // Validate semaphore-specific parameters. + if set != nil { + set := set.(*Set) if nsems > int32(set.Size()) { return nil, linuxerr.EINVAL } - if create && exclusive { - return nil, linuxerr.EEXIST - } return set, nil } - - if !create { - // Semaphore not found and should not be created. - return nil, syserror.ENOENT - } } // Zero is only valid if an existing set is found. @@ -163,9 +148,9 @@ func (r *Registry) FindOrCreate(ctx context.Context, key ipc.Key, nsems int32, m // Apply system limits. // - // Map semaphores and map indexes in a registry are of the same size, - // check map semaphores only here for the system limit. - if len(r.semaphores) >= setsMax { + // Map reg.objects and map indexes in a registry are of the same size, + // check map reg.objects only here for the system limit. + if r.reg.ObjectCount() >= setsMax { return nil, syserror.ENOSPC } if r.totalSems() > int(semsTotalMax-nsems) { @@ -173,9 +158,7 @@ func (r *Registry) FindOrCreate(ctx context.Context, key ipc.Key, nsems int32, m } // Finally create a new set. - owner := fs.FileOwnerFromContext(ctx) - perms := fs.FilePermsFromMode(mode) - return r.newSet(ctx, key, owner, owner, perms, nsems) + return r.newSetLocked(ctx, key, fs.FileOwnerFromContext(ctx), fs.FilePermsFromMode(mode), nsems) } // IPCInfo returns information about system-wide semaphore limits and parameters. @@ -202,7 +185,7 @@ func (r *Registry) SemInfo() *linux.SemInfo { defer r.mu.Unlock() info := r.IPCInfo() - info.SemUsz = uint32(len(r.semaphores)) + info.SemUsz = uint32(r.reg.ObjectCount()) info.SemAem = uint32(r.totalSems()) return info @@ -225,74 +208,59 @@ func (r *Registry) HighestIndex() int32 { return highestIndex } -// RemoveID removes set with give 'id' from the registry and marks the set as +// Remove removes set with give 'id' from the registry and marks the set as // dead. All waiters will be awakened and fail. -func (r *Registry) RemoveID(id ipc.ID, creds *auth.Credentials) error { +func (r *Registry) Remove(id ipc.ID, creds *auth.Credentials) error { r.mu.Lock() defer r.mu.Unlock() - set := r.semaphores[id] - if set == nil { - return linuxerr.EINVAL - } + r.reg.Remove(id, creds) + index, found := r.findIndexByID(id) if !found { // Inconsistent state. panic(fmt.Sprintf("unable to find an index for ID: %d", id)) } - - set.mu.Lock() - defer set.mu.Unlock() - - // "The effective user ID of the calling process must match the creator or - // owner of the semaphore set, or the caller must be privileged." - if !set.obj.CheckOwnership(creds) { - return linuxerr.EACCES - } - - delete(r.semaphores, set.obj.ID) delete(r.indexes, index) - set.destroy() + return nil } -func (r *Registry) newSet(ctx context.Context, key ipc.Key, owner, creator fs.FileOwner, perms fs.FilePermissions, nsems int32) (*Set, error) { - // Find the next available ID. - for id := r.lastIDUsed + 1; id != r.lastIDUsed; id++ { - // Handle wrap around. - if id < 0 { - id = 0 - continue - } - if r.semaphores[id] == nil { - index, found := r.findFirstAvailableIndex() - if !found { - panic("unable to find an available index") - } - r.indexes[index] = id - r.lastIDUsed = id - - set := &Set{ - registry: r, - obj: ipc.NewObject(r.userNS, ipc.ID(id), ipc.Key(key), creator, owner, perms), - changeTime: ktime.NowFromContext(ctx), - sems: make([]sem, nsems), - } - r.semaphores[id] = set +// newSetLocked creates a new Set using given fields. An error is returned if there +// are no more available identifiers. +// +// Precondition: r.mu must be held. +func (r *Registry) newSetLocked(ctx context.Context, key ipc.Key, creator fs.FileOwner, perms fs.FilePermissions, nsems int32) (*Set, error) { + set := &Set{ + registry: r, + obj: ipc.NewObject(r.reg.UserNS, ipc.Key(key), creator, creator, perms), + changeTime: ktime.NowFromContext(ctx), + sems: make([]sem, nsems), + } - return set, nil - } + err := r.reg.Register(set) + if err != nil { + return nil, err + } + + index, found := r.findFirstAvailableIndex() + if !found { + panic("unable to find an available index") } + r.indexes[index] = set.obj.ID - log.Warningf("Semaphore map is full, they must be leaking") - return nil, syserror.ENOMEM + return set, nil } // FindByID looks up a set given an ID. func (r *Registry) FindByID(id ipc.ID) *Set { r.mu.Lock() defer r.mu.Unlock() - return r.semaphores[id] + mech := r.reg.FindByID(id) + if mech == nil { + return nil + } + return mech.(*Set) } // FindByIndex looks up a set given an index. @@ -304,16 +272,7 @@ func (r *Registry) FindByIndex(index int32) *Set { if !present { return nil } - return r.semaphores[id] -} - -func (r *Registry) findByKey(key ipc.Key) *Set { - for _, v := range r.semaphores { - if v.obj.Key == key { - return v - } - } - return nil + return r.reg.FindByID(id).(*Set) } func (r *Registry) findIndexByID(id ipc.ID) (int32, bool) { @@ -336,9 +295,11 @@ func (r *Registry) findFirstAvailableIndex() (int32, bool) { func (r *Registry) totalSems() int { totalSems := 0 - for _, v := range r.semaphores { - totalSems += v.Size() - } + r.reg.ForAllObjects( + func(o ipc.Mechanism) { + totalSems += o.(*Set).Size() + }, + ) return totalSems } @@ -347,6 +308,23 @@ func (s *Set) ID() ipc.ID { return s.obj.ID } +// Object implements ipc.Mechanism.Object. +func (s *Set) Object() *ipc.Object { + return s.obj +} + +// Lock implements ipc.Mechanism.Lock. +func (s *Set) Lock() { + s.mu.Lock() +} + +// Unlock implements ipc.mechanism.Unlock. +// +// +checklocksignore +func (s *Set) Unlock() { + s.mu.Unlock() +} + func (s *Set) findSem(num int32) *sem { if num < 0 || int(num) >= s.Size() { return nil @@ -671,10 +649,10 @@ func (s *Set) AbortWait(num int32, ch chan struct{}) { // Waiter may not be found in case it raced with wakeWaiters(). } -// destroy destroys the set. +// Destroy implements ipc.Mechanism.Destroy. // // Preconditions: Caller must hold 's.mu'. -func (s *Set) destroy() { +func (s *Set) Destroy() { // Notify all waiters. They will fail on the next attempt to execute // operations and return error. s.dead = true diff --git a/pkg/sentry/kernel/semaphore/semaphore_test.go b/pkg/sentry/kernel/semaphore/semaphore_test.go index 0c7abb68e..2e4ab8121 100644 --- a/pkg/sentry/kernel/semaphore/semaphore_test.go +++ b/pkg/sentry/kernel/semaphore/semaphore_test.go @@ -139,6 +139,7 @@ func TestUnregister(t *testing.T) { ctx := contexttest.Context(t) r := NewRegistry(auth.NewRootUserNamespace()) set, err := r.FindOrCreate(ctx, 123, 2, linux.FileMode(0x600), true, true, true) + if err != nil { t.Fatalf("FindOrCreate() failed, err: %v", err) } @@ -156,8 +157,8 @@ func TestUnregister(t *testing.T) { } creds := auth.CredentialsFromContext(ctx) - if err := r.RemoveID(set.obj.ID, creds); err != nil { - t.Fatalf("RemoveID(%d) failed, err: %v", set.obj.ID, err) + if err := r.Remove(set.obj.ID, creds); err != nil { + t.Fatalf("Remove(%d) failed, err: %v", set.obj.ID, err) } if !set.dead { t.Fatalf("set is not dead: %+v", set) |