git: c050ea803eaa - main - jail: Handle a parent jail when a child is added to it

[Jamie Gritton]

The branch main has been updated by jamie:

URL: https://cgit.FreeBSD.org/src/commit/?id=c050ea803eaa1087313b86628b5d486c0e59e41b

commit c050ea803eaa1087313b86628b5d486c0e59e41b
Author:     Jamie Gritton <jamie at FreeBSD.org>
AuthorDate: 2021-01-29 05:51:09 +0000
Commit:     Jamie Gritton <jamie at FreeBSD.org>
CommitDate: 2021-01-29 05:51:09 +0000

    jail: Handle a parent jail when a child is added to it
    
    It's possible when adding a jail that its dying parent comes back to
    life.  Only allow that to happen when JAIL_DYING is specified.  And if
    it does happen, call PR_METHOD_CREATE on it.
---
 sys/kern/kern_jail.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/sys/kern/kern_jail.c b/sys/kern/kern_jail.c
index 064f1afa4133..ece0aa33e642 100644
--- a/sys/kern/kern_jail.c
+++ b/sys/kern/kern_jail.c
@@ -1105,6 +1105,14 @@ kern_jail_set(struct thread *td, struct uio *optuio, int flags)
 					    "jail \"%s\" not found", name);
 					goto done_deref;
 				}
+				if (!(flags & JAIL_DYING) &&
+				    !prison_isalive(ppr)) {
+					mtx_unlock(&ppr->pr_mtx);
+					error = ENOENT;
+					vfs_opterror(opts,
+					    "jail \"%s\" is dying", name);
+					goto done_deref;
+				}
 				mtx_unlock(&ppr->pr_mtx);
 				*namelc = '.';
 			}
@@ -1200,8 +1208,18 @@ kern_jail_set(struct thread *td, struct uio *optuio, int flags)
 			goto done_deref;
 		}
 		prison_hold(ppr);
-		refcount_acquire(&ppr->pr_uref);
-		mtx_unlock(&ppr->pr_mtx);
+		if (refcount_acquire(&ppr->pr_uref))
+			mtx_unlock(&ppr->pr_mtx);
+		else {
+			/* This brings the parent back to life. */
+			mtx_unlock(&ppr->pr_mtx);
+			error = osd_jail_call(ppr, PR_METHOD_CREATE, opts);
+			if (error) {
+				pr = ppr;
+				drflags |= PD_DEREF | PD_DEUREF;
+				goto done_deref;
+			}
+                }
 
 		if (jid == 0 && (jid = get_next_prid(&inspr)) == 0) {
 			error = EAGAIN;