From 17f701a3fba1da17bbf3baae8985868aa7710ad5 Mon Sep 17 00:00:00 2001 From: Edward Tomasz Napierala Date: Sat, 11 Jul 2020 13:08:16 +0000 Subject: [PATCH] Make linux stat(2) return the same st_dev for every devfs instance. The reason for this is to work around an idiosyncrasy of glibc getttynam(3) implementation: it checks whether st_dev returned for fd 0 is the same as st_dev returned for the target of /proc/self/fd/0 symlink, and with linux chroots having their own devfs instance, the check will fail if you chrooted into it. PR: kern/240767 Reviewed by: kib MFC after: 2 weeks Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D25559 --- sys/compat/linux/linux_stats.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/sys/compat/linux/linux_stats.c b/sys/compat/linux/linux_stats.c index f733a1ed7473..feffb442f2f6 100644 --- a/sys/compat/linux/linux_stats.c +++ b/sys/compat/linux/linux_stats.c @@ -70,6 +70,17 @@ translate_vnhook_major_minor(struct vnode *vp, struct stat *sb) sb->st_mode |= S_IFBLK; } + /* + * Return the same st_dev for every devfs instance. The reason + * for this is to work around an idiosyncrasy of glibc getttynam() + * implementation: it checks whether st_dev returned for fd 0 + * is the same as st_dev returned for the target of /proc/self/fd/0 + * symlink, and with linux chroots having their own devfs instance, + * the check will fail if you chroot into it. + */ + if (rootdevmp != NULL && vp->v_mount->mnt_vfc == rootdevmp->mnt_vfc) + sb->st_dev = rootdevmp->mnt_stat.f_fsid.val[0]; + if (vp->v_type == VCHR && vp->v_rdev != NULL && linux_driver_get_major_minor(devtoname(vp->v_rdev), &major, &minor) == 0) { @@ -110,6 +121,7 @@ translate_fd_major_minor(struct thread *td, int fd, struct stat *buf) { struct file *fp; struct vnode *vp; + struct mount *mp; int major, minor; /* @@ -123,6 +135,12 @@ translate_fd_major_minor(struct thread *td, int fd, struct stat *buf) buf->st_mode &= ~S_IFMT; buf->st_mode |= S_IFBLK; } + if (vp != NULL && rootdevmp != NULL) { + mp = vp->v_mount; + __compiler_membar(); + if (mp != NULL && mp->mnt_vfc == rootdevmp->mnt_vfc) + buf->st_dev = rootdevmp->mnt_stat.f_fsid.val[0]; + } if (vp != NULL && vp->v_rdev != NULL && linux_driver_get_major_minor(devtoname(vp->v_rdev), &major, &minor) == 0) {