diff options
Diffstat (limited to 'ipc/shm.c')
| -rw-r--r-- | ipc/shm.c | 48 |
1 files changed, 39 insertions, 9 deletions
diff --git a/ipc/shm.c b/ipc/shm.c index acefe44fefef..3cf48988d68c 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -225,6 +225,12 @@ static int __shm_open(struct vm_area_struct *vma) if (IS_ERR(shp)) return PTR_ERR(shp); + if (shp->shm_file != sfd->file) { + /* ID was reused */ + shm_unlock(shp); + return -EINVAL; + } + shp->shm_atim = ktime_get_real_seconds(); ipc_update_pid(&shp->shm_lprid, task_tgid(current)); shp->shm_nattch++; @@ -415,7 +421,7 @@ static int shm_split(struct vm_area_struct *vma, unsigned long addr) struct file *file = vma->vm_file; struct shm_file_data *sfd = shm_file_data(file); - if (sfd->vm_ops && sfd->vm_ops->split) + if (sfd->vm_ops->split) return sfd->vm_ops->split(vma, addr); return 0; @@ -455,8 +461,9 @@ static int shm_mmap(struct file *file, struct vm_area_struct *vma) int ret; /* - * In case of remap_file_pages() emulation, the file can represent - * removed IPC ID: propogate shm_lock() error to caller. + * In case of remap_file_pages() emulation, the file can represent an + * IPC ID that was removed, and possibly even reused by another shm + * segment already. Propagate this case as an error to caller. */ ret = __shm_open(vma); if (ret) @@ -480,6 +487,7 @@ static int shm_release(struct inode *ino, struct file *file) struct shm_file_data *sfd = shm_file_data(file); put_ipc_ns(sfd->ns); + fput(sfd->file); shm_file_data(file) = NULL; kfree(sfd); return 0; @@ -947,14 +955,14 @@ static int shmctl_stat(struct ipc_namespace *ns, int shmid, memset(tbuf, 0, sizeof(*tbuf)); rcu_read_lock(); - if (cmd == SHM_STAT) { + if (cmd == SHM_STAT || cmd == SHM_STAT_ANY) { shp = shm_obtain_object(ns, shmid); if (IS_ERR(shp)) { err = PTR_ERR(shp); goto out_unlock; } id = shp->shm_perm.id; - } else { + } else { /* IPC_STAT */ shp = shm_obtain_object_check(ns, shmid); if (IS_ERR(shp)) { err = PTR_ERR(shp); @@ -962,9 +970,20 @@ static int shmctl_stat(struct ipc_namespace *ns, int shmid, } } - err = -EACCES; - if (ipcperms(ns, &shp->shm_perm, S_IRUGO)) - goto out_unlock; + /* + * Semantically SHM_STAT_ANY ought to be identical to + * that functionality provided by the /proc/sysvipc/ + * interface. As such, only audit these calls and + * do not do traditional S_IRUGO permission checks on + * the ipc object. + */ + if (cmd == SHM_STAT_ANY) + audit_ipc_obj(&shp->shm_perm); + else { + err = -EACCES; + if (ipcperms(ns, &shp->shm_perm, S_IRUGO)) + goto out_unlock; + } err = security_shm_shmctl(&shp->shm_perm, cmd); if (err) @@ -1104,6 +1123,7 @@ long ksys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf) return err; } case SHM_STAT: + case SHM_STAT_ANY: case IPC_STAT: { err = shmctl_stat(ns, shmid, cmd, &sem64); if (err < 0) @@ -1282,6 +1302,7 @@ long compat_ksys_shmctl(int shmid, int cmd, void __user *uptr) return err; } case IPC_STAT: + case SHM_STAT_ANY: case SHM_STAT: err = shmctl_stat(ns, shmid, cmd, &sem64); if (err < 0) @@ -1432,7 +1453,16 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, file->f_mapping = shp->shm_file->f_mapping; sfd->id = shp->shm_perm.id; sfd->ns = get_ipc_ns(ns); - sfd->file = shp->shm_file; + /* + * We need to take a reference to the real shm file to prevent the + * pointer from becoming stale in cases where the lifetime of the outer + * file extends beyond that of the shm segment. It's not usually + * possible, but it can happen during remap_file_pages() emulation as + * that unmaps the memory, then does ->mmap() via file reference only. + * We'll deny the ->mmap() if the shm segment was since removed, but to + * detect shm ID reuse we need to compare the file pointers. + */ + sfd->file = get_file(shp->shm_file); sfd->vm_ops = NULL; err = security_mmap_file(file, prot, flags); |
