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- Change chroot_refuse_vdir_fds() to require that the passed in struct

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filedesc is already locked rather than having chroot() unlock the
  filedesc so chroot_refuse_vdir_fds() can immediately relock it.
- Reorder chroot() a bitso that we do the namei lookup before checking
  the process's struct filedesc.  This closes at least one potential race
  and allows us to only acquire the filedsec lock once in chroot().
- Push down Giant slightly into chroot().
This commit is contained in:
John Baldwin 2002-07-13 04:07:12 +00:00
parent d73b19ef9d
commit 03d7a9fffb
2 changed files with 36 additions and 32 deletions
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34
sys/kern/vfs_extattr.c
View File

@ -450,20 +450,17 @@ chroot_refuse_vdir_fds(fdp)
struct file *fp;
int fd;
FILEDESC_LOCK(fdp);
FILEDESC_LOCK_ASSERT(fdp, MA_OWNED);
for (fd = 0; fd < fdp->fd_nfiles ; fd++) {
fp = fget_locked(fdp, fd);
if (fp == NULL)
continue;
if (fp->f_type == DTYPE_VNODE) {
vp = (struct vnode *)fp->f_data;
if (vp->v_type == VDIR) {
FILEDESC_UNLOCK(fdp);
if (vp->v_type == VDIR)
return (EPERM);
}
}
}
FILEDESC_UNLOCK(fdp);
return (0);
}
@ -504,21 +501,18 @@ chroot(td, uap)
error = suser_cred(td->td_ucred, PRISON_ROOT);
if (error)
return (error);
NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_USERSPACE,
SCARG(uap, path), td);
mtx_lock(&Giant);
if ((error = change_dir(&nd, td)) != 0)
goto error;
FILEDESC_LOCK(fdp);
if (chroot_allow_open_directories == 0 ||
(chroot_allow_open_directories == 1 && fdp->fd_rdir != rootvnode)) {
FILEDESC_UNLOCK(fdp);
error = chroot_refuse_vdir_fds(fdp);
} else
FILEDESC_UNLOCK(fdp);
if (error)
return (error);
NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_USERSPACE,
SCARG(uap, path), td);
if ((error = change_dir(&nd, td)) != 0)
return (error);
NDFREE(&nd, NDF_ONLY_PNBUF);
FILEDESC_LOCK(fdp);
if (error)
goto error_unlock;
}
vp = fdp->fd_rdir;
fdp->fd_rdir = nd.ni_vp;
if (!fdp->fd_jdir) {
@ -526,8 +520,16 @@ chroot(td, uap)
VREF(fdp->fd_jdir);
}
FILEDESC_UNLOCK(fdp);
NDFREE(&nd, NDF_ONLY_PNBUF);
vrele(vp);
mtx_unlock(&Giant);
return (0);
error_unlock:
FILEDESC_UNLOCK(fdp);
error:
mtx_unlock(&Giant);
NDFREE(&nd, 0);
return (error);
}
/*

34
sys/kern/vfs_syscalls.c
View File

@ -450,20 +450,17 @@ chroot_refuse_vdir_fds(fdp)
struct file *fp;
int fd;
FILEDESC_LOCK(fdp);
FILEDESC_LOCK_ASSERT(fdp, MA_OWNED);
for (fd = 0; fd < fdp->fd_nfiles ; fd++) {
fp = fget_locked(fdp, fd);
if (fp == NULL)
continue;
if (fp->f_type == DTYPE_VNODE) {
vp = (struct vnode *)fp->f_data;
if (vp->v_type == VDIR) {
FILEDESC_UNLOCK(fdp);
if (vp->v_type == VDIR)
return (EPERM);
}
}
}
FILEDESC_UNLOCK(fdp);
return (0);
}
@ -504,21 +501,18 @@ chroot(td, uap)
error = suser_cred(td->td_ucred, PRISON_ROOT);
if (error)
return (error);
NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_USERSPACE,
SCARG(uap, path), td);
mtx_lock(&Giant);
if ((error = change_dir(&nd, td)) != 0)
goto error;
FILEDESC_LOCK(fdp);
if (chroot_allow_open_directories == 0 ||
(chroot_allow_open_directories == 1 && fdp->fd_rdir != rootvnode)) {
FILEDESC_UNLOCK(fdp);
error = chroot_refuse_vdir_fds(fdp);
} else
FILEDESC_UNLOCK(fdp);
if (error)
return (error);
NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_USERSPACE,
SCARG(uap, path), td);
if ((error = change_dir(&nd, td)) != 0)
return (error);
NDFREE(&nd, NDF_ONLY_PNBUF);
FILEDESC_LOCK(fdp);
if (error)
goto error_unlock;
}
vp = fdp->fd_rdir;
fdp->fd_rdir = nd.ni_vp;
if (!fdp->fd_jdir) {
@ -526,8 +520,16 @@ chroot(td, uap)
VREF(fdp->fd_jdir);
}
FILEDESC_UNLOCK(fdp);
NDFREE(&nd, NDF_ONLY_PNBUF);
vrele(vp);
mtx_unlock(&Giant);
return (0);
error_unlock:
FILEDESC_UNLOCK(fdp);
error:
mtx_unlock(&Giant);
NDFREE(&nd, 0);
return (error);
}
/*