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Make linux stat(2) return the same st_dev for every devfs instance.

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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
This commit is contained in:
Edward Tomasz Napierala 2020-07-11 13:08:16 +00:00
parent cf7becd216
commit 17f701a3fb
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=363093
1 changed files with 18 additions and 0 deletions
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18
sys/compat/linux/linux_stats.c
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@ -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) {