git: 957f7a2a58e5 - stable/14 - comsat: Improve use of setuid()

From: Ed Maste <emaste_at_FreeBSD.org>
Date: Mon, 02 Dec 2024 21:10:45 UTC
The branch stable/14 has been updated by emaste:

URL: https://cgit.FreeBSD.org/src/commit/?id=957f7a2a58e550bd31d8ebec67f99d19087746a2

commit 957f7a2a58e550bd31d8ebec67f99d19087746a2
Author:     Ed Maste <emaste@FreeBSD.org>
AuthorDate: 2024-11-27 20:36:46 +0000
Commit:     Ed Maste <emaste@FreeBSD.org>
CommitDate: 2024-12-02 21:10:31 +0000

    comsat: Improve use of setuid()
    
    Just return from jkfprintf if either (a) user lookup fails (that is,
    getpwnam fails) or (b) setuid() to the user's uid fails.  If comsat is
    invoked from inetd using the default of tty:tty we will now return due
    to setuid() failing rather than fopen() failing.
    
    PR:             270404
    Reviewed by:    kevans
    Sponsored by:   The FreeBSD Foundation
    Differential Revision: https://reviews.freebsd.org/D47823
    
    (cherry picked from commit 062b69ba045dc0fef3d9b8d73365d2798c05a480)
---
 libexec/comsat/comsat.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/libexec/comsat/comsat.c b/libexec/comsat/comsat.c
index 138881db9e4a..3f94f8d56201 100644
--- a/libexec/comsat/comsat.c
+++ b/libexec/comsat/comsat.c
@@ -225,8 +225,10 @@ jkfprintf(FILE *tp, char user[], char file[], off_t offset)
 	unsigned char line[BUFSIZ];
 
 	/* Set effective uid to user in case mail drop is on nfs */
-	if ((p = getpwnam(user)) != NULL)
-		(void) setuid(p->pw_uid);
+	if ((p = getpwnam(user)) == NULL)
+		return;
+	if (setuid(p->pw_uid) != 0)
+		return;
 
 	if ((fi = fopen(file, "r")) == NULL)
 		return;