git: 0746301c4995 - main - ssh: pass 0 to procctl(2) to operate on self

From: Ed Maste <emaste_at_FreeBSD.org>
Date: Fri, 21 Jan 2022 00:56:00 UTC
The branch main has been updated by emaste:

URL: https://cgit.FreeBSD.org/src/commit/?id=0746301c4995d9e4a82b0e5034b62e310694d1ef

commit 0746301c4995d9e4a82b0e5034b62e310694d1ef
Author:     Ed Maste <emaste@FreeBSD.org>
AuthorDate: 2022-01-20 18:41:39 +0000
Commit:     Ed Maste <emaste@FreeBSD.org>
CommitDate: 2022-01-21 00:54:49 +0000

    ssh: pass 0 to procctl(2) to operate on self
    
    As of f833ab9dd187 procctl(2) allows idtype P_PID with id = 0 as a
    shortcut for the calling process ID.  The shortcut also bypasses the
    p_cansee / p_candebug test (since the process is able to act on itself.)
    
    At present if the security.bsd.unprivileged_proc_debug sysctl is 0 then
    procctl(P_PID, getpid(), ... for a process to act on itself will fail,
    but procctl(P_PID, 0, ... will succeed.  This should likely be addressed
    with a kernel change.
    
    In any case the id = 0 shortcut is a tiny optimization for a process to
    act on itself and allows the self-procctl to succeed, so use it in ssh.
    
    Reported by:    Shawn Webb
    Reviewed by:    kib
    Sponsored by:   The FreeBSD Foundation
    Differential Revision:  https://reviews.freebsd.org/D33970
---
 crypto/openssh/platform-tracing.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crypto/openssh/platform-tracing.c b/crypto/openssh/platform-tracing.c
index 740a266b9432..e00f015fb01e 100644
--- a/crypto/openssh/platform-tracing.c
+++ b/crypto/openssh/platform-tracing.c
@@ -41,7 +41,7 @@ platform_disable_tracing(int strict)
 	/* On FreeBSD, we should make this process untraceable */
 	int disable_trace = PROC_TRACE_CTL_DISABLE;
 
-	if (procctl(P_PID, getpid(), PROC_TRACE_CTL, &disable_trace) && strict)
+	if (procctl(P_PID, 0, PROC_TRACE_CTL, &disable_trace) && strict)
 		fatal("unable to make the process untraceable");
 #endif
 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)