git: 8250729075f1 - releng/15.0 - jail: restore ktrace privileges for jailed root

The branch releng/15.0 has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=8250729075f13de2d47a5e799cc5996abf31fea5

commit 8250729075f13de2d47a5e799cc5996abf31fea5
Author:     Alexander Leidinger <netchild@FreeBSD.org>
AuthorDate: 2026-07-17 21:33:00 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2026-07-28 17:34:59 +0000

    jail: restore ktrace privileges for jailed root
    
    Commit 4be491e1b9b3 ("jail: Optionally allow audit session state to
    be configured in a jail") removed the #if 0 around the audit cases
    in prison_priv_check() and added the PR_ALLOW_SETAUDIT check under
    them.  This unintentionally captured the preceding case PRIV_KTRACE,
    which used to fall through the disabled block into the unconditional
    return (0) of the credential cases: since then, jailed root only has
    ktrace privileges (tracing processes with changed credentials, see
    ktrcanset()) when the unrelated allow.setaudit knob is enabled, and
    conversely gains them when that audit knob is turned on.
    
    Give PRIV_KTRACE back its own unconditional return (0), matching its
    comment and the pre-4be491e1b9b3 behaviour.
    
    Approved by:    so
    Security:       FreeBSD-SA-26:53.ktrace
    Security:       CVE-2026-58086
    Fixes:          4be491e1b9b3 ("jail: Optionally allow audit session state to be configured in a jail")
    Reviewed by:    markj
    Assisted-by:    Claude Code (Fable 5)
---
 sys/kern/kern_jail.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sys/kern/kern_jail.c b/sys/kern/kern_jail.c
index 40b2d7a69e3e..c4228febf5fb 100644
--- a/sys/kern/kern_jail.c
+++ b/sys/kern/kern_jail.c
@@ -4300,6 +4300,7 @@ prison_priv_check(struct ucred *cred, int priv)
 		 * Allow ktrace privileges for root in jail.
 		 */
 	case PRIV_KTRACE:
+		return (0);
 
 		/*
 		 * Allow jailed processes to configure audit identity and