diff options
| -rw-r--r-- | pkg/sentry/kernel/semaphore/semaphore.go | 29 | ||||
| -rw-r--r-- | pkg/sentry/syscalls/linux/linux64.go | 4 | ||||
| -rw-r--r-- | pkg/sentry/syscalls/linux/sys_sem.go | 20 | ||||
| -rw-r--r-- | test/syscalls/linux/semaphore.cc | 56 |
4 files changed, 105 insertions, 4 deletions
diff --git a/pkg/sentry/kernel/semaphore/semaphore.go b/pkg/sentry/kernel/semaphore/semaphore.go index c00fa1138..c39ecfb8f 100644 --- a/pkg/sentry/kernel/semaphore/semaphore.go +++ b/pkg/sentry/kernel/semaphore/semaphore.go @@ -283,6 +283,33 @@ func (s *Set) Change(ctx context.Context, creds *auth.Credentials, owner fs.File return nil } +// GetStat extracts semid_ds information from the set. +func (s *Set) GetStat(creds *auth.Credentials) (*linux.SemidDS, error) { + s.mu.Lock() + defer s.mu.Unlock() + + // "The calling process must have read permission on the semaphore set." + if !s.checkPerms(creds, fs.PermMask{Read: true}) { + return nil, syserror.EACCES + } + + ds := &linux.SemidDS{ + SemPerm: linux.IPCPerm{ + Key: uint32(s.key), + UID: uint32(creds.UserNamespace.MapFromKUID(s.owner.UID)), + GID: uint32(creds.UserNamespace.MapFromKGID(s.owner.GID)), + CUID: uint32(creds.UserNamespace.MapFromKUID(s.creator.UID)), + CGID: uint32(creds.UserNamespace.MapFromKGID(s.creator.GID)), + Mode: uint16(s.perms.LinuxMode()), + Seq: 0, // IPC sequence not supported. + }, + SemOTime: s.opTime.TimeT(), + SemCTime: s.changeTime.TimeT(), + SemNSems: uint64(s.Size()), + } + return ds, nil +} + // SetVal overrides a semaphore value, waking up waiters as needed. func (s *Set) SetVal(ctx context.Context, num int32, val int16, creds *auth.Credentials, pid int32) error { if val < 0 || val > valueMax { @@ -320,7 +347,7 @@ func (s *Set) SetValAll(ctx context.Context, vals []uint16, creds *auth.Credenti } for _, val := range vals { - if val < 0 || val > valueMax { + if val > valueMax { return syserror.ERANGE } } diff --git a/pkg/sentry/syscalls/linux/linux64.go b/pkg/sentry/syscalls/linux/linux64.go index 9c9def7cd..36902d177 100644 --- a/pkg/sentry/syscalls/linux/linux64.go +++ b/pkg/sentry/syscalls/linux/linux64.go @@ -118,7 +118,7 @@ var AMD64 = &kernel.SyscallTable{ 63: syscalls.Supported("uname", Uname), 64: syscalls.Supported("semget", Semget), 65: syscalls.PartiallySupported("semop", Semop, "Option SEM_UNDO not supported.", nil), - 66: syscalls.PartiallySupported("semctl", Semctl, "Options IPC_INFO, SEM_INFO, IPC_STAT, SEM_STAT, SEM_STAT_ANY, GETNCNT, GETZCNT not supported.", nil), + 66: syscalls.PartiallySupported("semctl", Semctl, "Options IPC_INFO, SEM_INFO, SEM_STAT, SEM_STAT_ANY, GETNCNT, GETZCNT not supported.", nil), 67: syscalls.Supported("shmdt", Shmdt), 68: syscalls.ErrorWithEvent("msgget", syserror.ENOSYS, "", []string{"gvisor.dev/issue/135"}), // TODO(b/29354921) 69: syscalls.ErrorWithEvent("msgsnd", syserror.ENOSYS, "", []string{"gvisor.dev/issue/135"}), // TODO(b/29354921) @@ -619,7 +619,7 @@ var ARM64 = &kernel.SyscallTable{ 188: syscalls.ErrorWithEvent("msgrcv", syserror.ENOSYS, "", []string{"gvisor.dev/issue/135"}), // TODO(b/29354921) 189: syscalls.ErrorWithEvent("msgsnd", syserror.ENOSYS, "", []string{"gvisor.dev/issue/135"}), // TODO(b/29354921) 190: syscalls.Supported("semget", Semget), - 191: syscalls.PartiallySupported("semctl", Semctl, "Options IPC_INFO, SEM_INFO, IPC_STAT, SEM_STAT, SEM_STAT_ANY, GETNCNT, GETZCNT not supported.", nil), + 191: syscalls.PartiallySupported("semctl", Semctl, "Options IPC_INFO, SEM_INFO, SEM_STAT, SEM_STAT_ANY, GETNCNT, GETZCNT not supported.", nil), 192: syscalls.ErrorWithEvent("semtimedop", syserror.ENOSYS, "", []string{"gvisor.dev/issue/137"}), 193: syscalls.PartiallySupported("semop", Semop, "Option SEM_UNDO not supported.", nil), 194: syscalls.PartiallySupported("shmget", Shmget, "Option SHM_HUGETLB is not supported.", nil), diff --git a/pkg/sentry/syscalls/linux/sys_sem.go b/pkg/sentry/syscalls/linux/sys_sem.go index 47dadb800..c2d4bf805 100644 --- a/pkg/sentry/syscalls/linux/sys_sem.go +++ b/pkg/sentry/syscalls/linux/sys_sem.go @@ -129,9 +129,17 @@ func Semctl(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal v, err := getPID(t, id, num) return uintptr(v), nil, err + case linux.IPC_STAT: + arg := args[3].Pointer() + ds, err := ipcStat(t, id) + if err == nil { + _, err = ds.CopyOut(t, arg) + } + + return 0, nil, err + case linux.IPC_INFO, linux.SEM_INFO, - linux.IPC_STAT, linux.SEM_STAT, linux.SEM_STAT_ANY, linux.GETNCNT, @@ -171,6 +179,16 @@ func ipcSet(t *kernel.Task, id int32, uid auth.UID, gid auth.GID, perms fs.FileP return set.Change(t, creds, owner, perms) } +func ipcStat(t *kernel.Task, id int32) (*linux.SemidDS, error) { + r := t.IPCNamespace().SemaphoreRegistry() + set := r.FindByID(id) + if set == nil { + return nil, syserror.EINVAL + } + creds := auth.CredentialsFromContext(t) + return set.GetStat(creds) +} + func setVal(t *kernel.Task, id int32, num int32, val int16) error { r := t.IPCNamespace().SemaphoreRegistry() set := r.FindByID(id) diff --git a/test/syscalls/linux/semaphore.cc b/test/syscalls/linux/semaphore.cc index e9b131ca9..ed6a1c2aa 100644 --- a/test/syscalls/linux/semaphore.cc +++ b/test/syscalls/linux/semaphore.cc @@ -486,6 +486,62 @@ TEST(SemaphoreTest, SemIpcSet) { ASSERT_THAT(semop(sem.get(), &buf, 1), SyscallFailsWithErrno(EACCES)); } +TEST(SemaphoreTest, SemCtlIpcStat) { + // Drop CAP_IPC_OWNER which allows us to bypass semaphore permissions. + ASSERT_NO_ERRNO(SetCapability(CAP_IPC_OWNER, false)); + const uid_t kUid = getuid(); + const gid_t kGid = getgid(); + time_t start_time = time(nullptr); + + AutoSem sem(semget(IPC_PRIVATE, 10, 0600 | IPC_CREAT)); + ASSERT_THAT(sem.get(), SyscallSucceeds()); + + struct semid_ds ds; + EXPECT_THAT(semctl(sem.get(), 0, IPC_STAT, &ds), SyscallSucceeds()); + + EXPECT_EQ(ds.sem_perm.__key, IPC_PRIVATE); + EXPECT_EQ(ds.sem_perm.uid, kUid); + EXPECT_EQ(ds.sem_perm.gid, kGid); + EXPECT_EQ(ds.sem_perm.cuid, kUid); + EXPECT_EQ(ds.sem_perm.cgid, kGid); + EXPECT_EQ(ds.sem_perm.mode, 0600); + // Last semop time is not set on creation. + EXPECT_EQ(ds.sem_otime, 0); + EXPECT_GE(ds.sem_ctime, start_time); + EXPECT_EQ(ds.sem_nsems, 10); + + // The timestamps only have a resolution of seconds; slow down so we actually + // see the timestamps change. + absl::SleepFor(absl::Seconds(1)); + + // Set semid_ds structure of the set. + auto last_ctime = ds.sem_ctime; + start_time = time(nullptr); + struct semid_ds semid_to_set = {}; + semid_to_set.sem_perm.uid = kUid; + semid_to_set.sem_perm.gid = kGid; + semid_to_set.sem_perm.mode = 0666; + ASSERT_THAT(semctl(sem.get(), 0, IPC_SET, &semid_to_set), SyscallSucceeds()); + struct sembuf buf = {}; + buf.sem_op = 1; + ASSERT_THAT(semop(sem.get(), &buf, 1), SyscallSucceeds()); + + EXPECT_THAT(semctl(sem.get(), 0, IPC_STAT, &ds), SyscallSucceeds()); + EXPECT_EQ(ds.sem_perm.mode, 0666); + EXPECT_GE(ds.sem_otime, start_time); + EXPECT_GT(ds.sem_ctime, last_ctime); + + // An invalid semid fails the syscall with errno EINVAL. + EXPECT_THAT(semctl(sem.get() + 1, 0, IPC_STAT, &ds), + SyscallFailsWithErrno(EINVAL)); + + // Make semaphore not readable and check the signal fails. + semid_to_set.sem_perm.mode = 0200; + ASSERT_THAT(semctl(sem.get(), 0, IPC_SET, &semid_to_set), SyscallSucceeds()); + EXPECT_THAT(semctl(sem.get(), 0, IPC_STAT, &ds), + SyscallFailsWithErrno(EACCES)); +} + } // namespace } // namespace testing } // namespace gvisor |