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Date:      Fri, 12 Mar 2021 18:49:57 GMT
From:      Jamie Gritton <jamie@FreeBSD.org>
To:        src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org
Subject:   git: d2bbfc375487 - stable/13 - MFC jail: Don't allow jails under dying parents
Message-ID:  <202103121849.12CInvSA047436@gitrepo.freebsd.org>

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The branch stable/13 has been updated by jamie:

URL: https://cgit.FreeBSD.org/src/commit/?id=d2bbfc3754871f08e487ac59e5c03a088c8acad2

commit d2bbfc3754871f08e487ac59e5c03a088c8acad2
Author:     Jamie Gritton <jamie@FreeBSD.org>
AuthorDate: 2021-02-23 01:04:06 +0000
Commit:     Jamie Gritton <jamie@FreeBSD.org>
CommitDate: 2021-03-12 18:49:13 +0000

    MFC jail: Don't allow jails under dying parents
    
    If a jail is created with jail_set(...JAIL_DYING), and it has a parent
    currently in a dying state, that will bring the parent jail back to
    life.  Restrict that to require that the parent itself be explicitly
    brought back first, and not implicitly created along with the new
    child jail.
    
    Differential Revision:  https://reviews.freebsd.org/D28515
    
    (cherry picked from commit 0a2a96f35a4c2dab3486438680fa289e12971e4b)
    
    MFC jail: Fix locking on an early jail_set error.
    
    I had locked allprison_lock without immediately setting PD_LIST_LOCKED.
    
    (cherry picked from commit 108a9384e9e945cccba73c959f7e9cdb023cbcad)
---
 sys/kern/kern_jail.c | 40 +++++++++++++++++-----------------------
 1 file changed, 17 insertions(+), 23 deletions(-)

diff --git a/sys/kern/kern_jail.c b/sys/kern/kern_jail.c
index 547fca778dcf..b5c8f6ebf9be 100644
--- a/sys/kern/kern_jail.c
+++ b/sys/kern/kern_jail.c
@@ -992,7 +992,6 @@ kern_jail_set(struct thread *td, struct uio *optuio, int flags)
 	 * This abuses the file error codes ENOENT and EEXIST.
 	 */
 	pr = NULL;
-	ppr = mypr;
 	inspr = NULL;
 	if (cuflags == JAIL_CREATE && jid == 0 && name != NULL) {
 		namelc = strrchr(name, '.');
@@ -1002,6 +1001,12 @@ kern_jail_set(struct thread *td, struct uio *optuio, int flags)
 	}
 	sx_xlock(&allprison_lock);
 	drflags = PD_LIST_XLOCKED;
+	ppr = mypr;
+	if (!prison_isalive(ppr)) {
+		/* This jail is dying.  This process will surely follow. */
+		error = EAGAIN;
+		goto done_deref;
+	}
 	if (jid != 0) {
 		if (jid < 0) {
 			error = EINVAL;
@@ -1024,7 +1029,6 @@ kern_jail_set(struct thread *td, struct uio *optuio, int flags)
 			break;
 		}
 		if (pr != NULL) {
-			ppr = pr->pr_parent;
 			/* Create: jid must not exist. */
 			if (cuflags == JAIL_CREATE) {
 				/*
@@ -1046,6 +1050,13 @@ kern_jail_set(struct thread *td, struct uio *optuio, int flags)
 				vfs_opterror(opts, "jail %d not found", jid);
 				goto done_deref;
 			}
+			ppr = pr->pr_parent;
+			if (!prison_isalive(ppr)) {
+				error = ENOENT;
+				vfs_opterror(opts, "jail %d is dying",
+				    ppr->pr_id);
+				goto done_deref;
+			}
 			if (!prison_isalive(pr)) {
 				if (!(flags & JAIL_DYING)) {
 					error = ENOENT;
@@ -1111,15 +1122,13 @@ 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);
+				mtx_unlock(&ppr->pr_mtx);
+				if (!prison_isalive(ppr)) {
 					error = ENOENT;
 					vfs_opterror(opts,
 					    "jail \"%s\" is dying", name);
 					goto done_deref;
 				}
-				mtx_unlock(&ppr->pr_mtx);
 				*namelc = '.';
 			}
 			namelc++;
@@ -1198,26 +1207,9 @@ kern_jail_set(struct thread *td, struct uio *optuio, int flags)
 				vfs_opterror(opts, "prison limit exceeded");
 				goto done_deref;
 			}
-		prison_hold(ppr);
-		if (!refcount_acquire_if_not_zero(&ppr->pr_uref)) {
-			/* This brings the parent back to life. */
-			mtx_lock(&ppr->pr_mtx);
-			refcount_acquire(&ppr->pr_uref);
-			ppr->pr_state = PRISON_STATE_ALIVE;
-			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;
 			vfs_opterror(opts, "no available jail IDs");
-			pr = ppr;
-			drflags |= PD_DEREF | PD_DEUREF;
 			goto done_deref;
 		}
 
@@ -1237,6 +1229,8 @@ kern_jail_set(struct thread *td, struct uio *optuio, int flags)
 			TAILQ_INSERT_TAIL(&allprison, pr, pr_list);
 
 		pr->pr_parent = ppr;
+		prison_hold(ppr);
+		prison_proc_hold(ppr);
 		LIST_INSERT_HEAD(&ppr->pr_children, pr, pr_sibling);
 		for (tpr = ppr; tpr != NULL; tpr = tpr->pr_parent)
 			tpr->pr_childcount++;



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