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authorJamie Gritton <jamie@FreeBSD.org>2021-02-19 22:13:35 +0000
committerJamie Gritton <jamie@FreeBSD.org>2021-02-19 22:13:35 +0000
commitd4380c0cdd0517dc038403dd5c99242ce78bdeb5 (patch)
tree7a3e2496b46683bb7ce41e27c65d3b3c77edd1ad
parent0f9544d03e89d180f94a7a84b110ec7d2b6c625a (diff)
downloadsrc-d4380c0cdd0517dc038403dd5c99242ce78bdeb5.tar.gz
src-d4380c0cdd0517dc038403dd5c99242ce78bdeb5.zip
jail: Change both root and working directories in jail_attach(2)
jail_attach(2) performs an internal chroot operation, leaving it up to the calling process to assure the working directory is inside the jail. Add a matching internal chdir operation to the jail's root. Also ignore kern.chroot_allow_open_directories, and always disallow the operation if there are any directory descriptors open. Reported by: mjg Approved by: markj, kib MFC after: 3 days
-rw-r--r--lib/libc/sys/jail.25
-rw-r--r--sys/kern/kern_descrip.c45
-rw-r--r--sys/kern/kern_jail.c2
-rw-r--r--sys/sys/filedesc.h1
4 files changed, 48 insertions, 5 deletions
diff --git a/lib/libc/sys/jail.2 b/lib/libc/sys/jail.2
index 2e13a6c3a381..82c2e97d4a7b 100644
--- a/lib/libc/sys/jail.2
+++ b/lib/libc/sys/jail.2
@@ -25,7 +25,7 @@
.\"
.\" $FreeBSD$
.\"
-.Dd February 8, 2012
+.Dd February 19, 2021
.Dt JAIL 2
.Os
.Sh NAME
@@ -228,6 +228,9 @@ The
system call attaches the current process to an existing jail,
identified by
.Fa jid .
+It changes the process's root and current directories to the jail's
+.Va path
+directory.
.Pp
The
.Fn jail_remove
diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
index 43cedfe2199b..0813b6c8f3b8 100644
--- a/sys/kern/kern_descrip.c
+++ b/sys/kern/kern_descrip.c
@@ -3795,9 +3795,8 @@ pwd_drop(struct pwd *pwd)
}
/*
-* Common routine for kern_chroot() and jail_attach(). The caller is
-* responsible for invoking priv_check() and mac_vnode_check_chroot() to
-* authorize this operation.
+* The caller is responsible for invoking priv_check() and
+* mac_vnode_check_chroot() to authorize this operation.
*/
int
pwd_chroot(struct thread *td, struct vnode *vp)
@@ -3859,6 +3858,46 @@ pwd_chdir(struct thread *td, struct vnode *vp)
pwd_drop(oldpwd);
}
+/*
+ * jail_attach(2) changes both root and working directories.
+ */
+int
+pwd_chroot_chdir(struct thread *td, struct vnode *vp)
+{
+ struct pwddesc *pdp;
+ struct filedesc *fdp;
+ struct pwd *newpwd, *oldpwd;
+ int error;
+
+ fdp = td->td_proc->p_fd;
+ pdp = td->td_proc->p_pd;
+ newpwd = pwd_alloc();
+ FILEDESC_SLOCK(fdp);
+ PWDDESC_XLOCK(pdp);
+ oldpwd = PWDDESC_XLOCKED_LOAD_PWD(pdp);
+ error = chroot_refuse_vdir_fds(fdp);
+ FILEDESC_SUNLOCK(fdp);
+ if (error != 0) {
+ PWDDESC_XUNLOCK(pdp);
+ pwd_drop(newpwd);
+ return (error);
+ }
+
+ vrefact(vp);
+ newpwd->pwd_rdir = vp;
+ vrefact(vp);
+ newpwd->pwd_cdir = vp;
+ if (oldpwd->pwd_jdir == NULL) {
+ vrefact(vp);
+ newpwd->pwd_jdir = vp;
+ }
+ pwd_fill(oldpwd, newpwd);
+ pwd_set(pdp, newpwd);
+ PWDDESC_XUNLOCK(pdp);
+ pwd_drop(oldpwd);
+ return (0);
+}
+
void
pwd_ensure_dirs(void)
{
diff --git a/sys/kern/kern_jail.c b/sys/kern/kern_jail.c
index b56c889eeb7e..90ab69a372d2 100644
--- a/sys/kern/kern_jail.c
+++ b/sys/kern/kern_jail.c
@@ -2495,7 +2495,7 @@ do_jail_attach(struct thread *td, struct prison *pr)
goto e_unlock;
#endif
VOP_UNLOCK(pr->pr_root);
- if ((error = pwd_chroot(td, pr->pr_root)))
+ if ((error = pwd_chroot_chdir(td, pr->pr_root)))
goto e_revert_osd;
newcred = crget();
diff --git a/sys/sys/filedesc.h b/sys/sys/filedesc.h
index 890232b7f160..8c5aa258ed28 100644
--- a/sys/sys/filedesc.h
+++ b/sys/sys/filedesc.h
@@ -333,6 +333,7 @@ void pdunshare(struct thread *td);
void pwd_chdir(struct thread *td, struct vnode *vp);
int pwd_chroot(struct thread *td, struct vnode *vp);
+int pwd_chroot_chdir(struct thread *td, struct vnode *vp);
void pwd_ensure_dirs(void);
void pwd_set_rootvnode(void);