return 0;
}
+static struct vfsmount *lookup_mnt_in_ns(u64 id, struct mnt_namespace *ns)
+{
+ struct mount *mnt = mnt_find_id_at(ns, id);
+
+ if (!mnt || mnt->mnt_id_unique != id)
+ return NULL;
+
+ return &mnt->mnt;
+}
+
+struct kstatmount {
+ struct statmount __user *const buf;
+ size_t const bufsize;
+ struct vfsmount *const mnt;
+ u64 const mask;
+ struct seq_file seq;
+ struct path root;
+ struct statmount sm;
+ size_t pos;
+ int err;
+};
+
+typedef int (*statmount_func_t)(struct kstatmount *);
+
+static int statmount_string_seq(struct kstatmount *s, statmount_func_t func)
+{
+ size_t rem = s->bufsize - s->pos - sizeof(s->sm);
+ struct seq_file *seq = &s->seq;
+ int ret;
+
+ seq->count = 0;
+ seq->size = min(seq->size, rem);
+ seq->buf = kvmalloc(seq->size, GFP_KERNEL_ACCOUNT);
+ if (!seq->buf)
+ return -ENOMEM;
+
+ ret = func(s);
+ if (ret)
+ return ret;
+
+ if (seq_has_overflowed(seq)) {
+ if (seq->size == rem)
+ return -EOVERFLOW;
+ seq->size *= 2;
+ if (seq->size > MAX_RW_COUNT)
+ return -ENOMEM;
+ kvfree(seq->buf);
+ return 0;
+ }
+
+ /* Done */
+ return 1;
+}
+
+static void statmount_string(struct kstatmount *s, u64 mask, statmount_func_t func,
+ u32 *str)
+{
+ int ret = s->pos + sizeof(s->sm) >= s->bufsize ? -EOVERFLOW : 0;
+ struct statmount *sm = &s->sm;
+ struct seq_file *seq = &s->seq;
+
+ if (s->err || !(s->mask & mask))
+ return;
+
+ seq->size = PAGE_SIZE;
+ while (!ret)
+ ret = statmount_string_seq(s, func);
+
+ if (ret < 0) {
+ s->err = ret;
+ } else {
+ seq->buf[seq->count++] = '\0';
+ if (copy_to_user(s->buf->str + s->pos, seq->buf, seq->count)) {
+ s->err = -EFAULT;
+ } else {
+ *str = s->pos;
+ s->pos += seq->count;
+ }
+ }
+ kvfree(seq->buf);
+ sm->mask |= mask;
+}
+
+static void statmount_numeric(struct kstatmount *s, u64 mask, statmount_func_t func)
+{
+ if (s->err || !(s->mask & mask))
+ return;
+
+ s->err = func(s);
+ s->sm.mask |= mask;
+}
+
+static u64 mnt_to_attr_flags(struct vfsmount *mnt)
+{
+ unsigned int mnt_flags = READ_ONCE(mnt->mnt_flags);
+ u64 attr_flags = 0;
+
+ if (mnt_flags & MNT_READONLY)
+ attr_flags |= MOUNT_ATTR_RDONLY;
+ if (mnt_flags & MNT_NOSUID)
+ attr_flags |= MOUNT_ATTR_NOSUID;
+ if (mnt_flags & MNT_NODEV)
+ attr_flags |= MOUNT_ATTR_NODEV;
+ if (mnt_flags & MNT_NOEXEC)
+ attr_flags |= MOUNT_ATTR_NOEXEC;
+ if (mnt_flags & MNT_NODIRATIME)
+ attr_flags |= MOUNT_ATTR_NODIRATIME;
+ if (mnt_flags & MNT_NOSYMFOLLOW)
+ attr_flags |= MOUNT_ATTR_NOSYMFOLLOW;
+
+ if (mnt_flags & MNT_NOATIME)
+ attr_flags |= MOUNT_ATTR_NOATIME;
+ else if (mnt_flags & MNT_RELATIME)
+ attr_flags |= MOUNT_ATTR_RELATIME;
+ else
+ attr_flags |= MOUNT_ATTR_STRICTATIME;
+
+ if (is_idmapped_mnt(mnt))
+ attr_flags |= MOUNT_ATTR_IDMAP;
+
+ return attr_flags;
+}
+
+static u64 mnt_to_propagation_flags(struct mount *m)
+{
+ u64 propagation = 0;
+
+ if (IS_MNT_SHARED(m))
+ propagation |= MS_SHARED;
+ if (IS_MNT_SLAVE(m))
+ propagation |= MS_SLAVE;
+ if (IS_MNT_UNBINDABLE(m))
+ propagation |= MS_UNBINDABLE;
+ if (!propagation)
+ propagation |= MS_PRIVATE;
+
+ return propagation;
+}
+
+static int statmount_sb_basic(struct kstatmount *s)
+{
+ struct super_block *sb = s->mnt->mnt_sb;
+
+ s->sm.sb_dev_major = MAJOR(sb->s_dev);
+ s->sm.sb_dev_minor = MINOR(sb->s_dev);
+ s->sm.sb_magic = sb->s_magic;
+ s->sm.sb_flags = sb->s_flags & (SB_RDONLY|SB_SYNCHRONOUS|SB_DIRSYNC|SB_LAZYTIME);
+
+ return 0;
+}
+
+static int statmount_mnt_basic(struct kstatmount *s)
+{
+ struct mount *m = real_mount(s->mnt);
+
+ s->sm.mnt_id = m->mnt_id_unique;
+ s->sm.mnt_parent_id = m->mnt_parent->mnt_id_unique;
+ s->sm.mnt_id_old = m->mnt_id;
+ s->sm.mnt_parent_id_old = m->mnt_parent->mnt_id;
+ s->sm.mnt_attr = mnt_to_attr_flags(&m->mnt);
+ s->sm.mnt_propagation = mnt_to_propagation_flags(m);
+ s->sm.mnt_peer_group = IS_MNT_SHARED(m) ? m->mnt_group_id : 0;
+ s->sm.mnt_master = IS_MNT_SLAVE(m) ? m->mnt_master->mnt_group_id : 0;
+
+ return 0;
+}
+
+static int statmount_propagate_from(struct kstatmount *s)
+{
+ struct mount *m = real_mount(s->mnt);
+
+ if (!IS_MNT_SLAVE(m))
+ return 0;
+
+ s->sm.propagate_from = get_dominating_id(m, ¤t->fs->root);
+
+ return 0;
+}
+
+static int statmount_mnt_root(struct kstatmount *s)
+{
+ struct seq_file *seq = &s->seq;
+ int err = show_path(seq, s->mnt->mnt_root);
+
+ if (!err && !seq_has_overflowed(seq)) {
+ seq->buf[seq->count] = '\0';
+ seq->count = string_unescape_inplace(seq->buf, UNESCAPE_OCTAL);
+ }
+ return err;
+}
+
+static int statmount_mnt_point(struct kstatmount *s)
+{
+ struct vfsmount *mnt = s->mnt;
+ struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
+ int err = seq_path_root(&s->seq, &mnt_path, &s->root, "");
+
+ return err == SEQ_SKIP ? 0 : err;
+}
+
+static int statmount_fs_type(struct kstatmount *s)
+{
+ struct seq_file *seq = &s->seq;
+ struct super_block *sb = s->mnt->mnt_sb;
+
+ seq_puts(seq, sb->s_type->name);
+ return 0;
+}
+
+static int do_statmount(struct kstatmount *s)
+{
+ struct statmount *sm = &s->sm;
+ struct mount *m = real_mount(s->mnt);
+ size_t copysize = min_t(size_t, s->bufsize, sizeof(*sm));
+ int err;
+
+ /*
+ * Don't trigger audit denials. We just want to determine what
+ * mounts to show users.
+ */
+ if (!is_path_reachable(m, m->mnt.mnt_root, &s->root) &&
+ !ns_capable_noaudit(&init_user_ns, CAP_SYS_ADMIN))
+ return -EPERM;
+
+ err = security_sb_statfs(s->mnt->mnt_root);
+ if (err)
+ return err;
+
+ statmount_numeric(s, STATMOUNT_SB_BASIC, statmount_sb_basic);
+ statmount_numeric(s, STATMOUNT_MNT_BASIC, statmount_mnt_basic);
+ statmount_numeric(s, STATMOUNT_PROPAGATE_FROM, statmount_propagate_from);
+ statmount_string(s, STATMOUNT_FS_TYPE, statmount_fs_type, &sm->fs_type);
+ statmount_string(s, STATMOUNT_MNT_ROOT, statmount_mnt_root, &sm->mnt_root);
+ statmount_string(s, STATMOUNT_MNT_POINT, statmount_mnt_point, &sm->mnt_point);
+
+ if (s->err)
+ return s->err;
+
+ /* Return the number of bytes copied to the buffer */
+ sm->size = copysize + s->pos;
+
+ if (copy_to_user(s->buf, sm, copysize))
+ return -EFAULT;
+
+ return 0;
+}
+
+SYSCALL_DEFINE4(statmount, const struct mnt_id_req __user *, req,
+ struct statmount __user *, buf, size_t, bufsize,
+ unsigned int, flags)
+{
+ struct vfsmount *mnt;
+ struct mnt_id_req kreq;
+ int ret;
+
+ if (flags)
+ return -EINVAL;
+
+ if (copy_from_user(&kreq, req, sizeof(kreq)))
+ return -EFAULT;
+
+ down_read(&namespace_sem);
+ mnt = lookup_mnt_in_ns(kreq.mnt_id, current->nsproxy->mnt_ns);
+ ret = -ENOENT;
+ if (mnt) {
+ struct kstatmount s = {
+ .mask = kreq.request_mask,
+ .buf = buf,
+ .bufsize = bufsize,
+ .mnt = mnt,
+ };
+
+ get_fs_root(current->fs, &s.root);
+ ret = do_statmount(&s);
+ path_put(&s.root);
+ }
+ up_read(&namespace_sem);
+
+ return ret;
+}
+
static void __init init_mount_tree(void)
{
struct vfsmount *mnt;
projects / linux-2.6-block.git / blobdiff