Author: kevans
Date: Sun Jun 2 14:03:56 2019
New Revision: 348509
URL: https://svnweb.freebsd.org/changeset/base/348509
Log:
jail_getid(3): add special-case immediate return for jid 0
As depicted in the comment: jid 0 always exists, but the lookup will fail as
it does not appear in the kernel's alljails list being a special jail. Some
callers will expect/rely on this, and we have no reason to lie because it
does always exist.
Reported by: Stefan Hegnauer <stefan.hegnauer gmx ch>
MFC after: soon (regression, breaks inspecting jail host bits, partial
revert)
Modified:
head/lib/libjail/jail_getid.c
Modified: head/lib/libjail/jail_getid.c
==============================================================================
--- head/lib/libjail/jail_getid.c Sun Jun 2 09:28:50 2019
(r348508)
+++ head/lib/libjail/jail_getid.c Sun Jun 2 14:03:56 2019
(r348509)
@@ -54,6 +54,15 @@ jail_getid(const char *name)
jid = strtoul(name, &ep, 10);
if (*name && !*ep) {
+ /*
+ * jid == 0 is a special case; it will not appear in the
+ * kernel's jail list, but naturally processes will be assigned
+ * to it because it is prison 0. Trivially return this one
+ * without a trip to the kernel, because it always exists but
+ * the lookup won't succeed.
+ */
+ if (jid == 0)
+ return jid;
jiov[0].iov_base = __DECONST(char *, "jid");
jiov[0].iov_len = sizeof("jid");
jiov[1].iov_base = &jid;
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