From nobody Tue Aug 25 16:01:24 2026 X-Original-To: dev-commits-src-all@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4hTsw51mNvz6pbjW for ; Tue, 25 Aug 2026 16:01:25 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "YR2" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4hTsw444wFz44hM for ; Tue, 25 Aug 2026 16:01:24 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1787673684; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=CE+reyvEJ2gNL+2ODCliJydtj6eQsgkA3PJRG7f/d+c=; b=VCz55fRADDcfLQCr+rzS8Lt5uTL5mRaTuXBhRKp8d1FrkS7ohTXuCLWZUmqjH5wD1Zmbne bwfRCK0dbtEO/mJfW1VbKmYFggrXQD+aMRYkWeGOB1CXN4brdSHna3xSpc0E41G3H2haRi Syq+II3j9C2Nw0DvK9MMnW/Aqy3YEkukDVE9g97ovO/CKzGre9XtCggLo322mWm5ftFuYf QnvYvq0AR7lTJYtdl31Knb0t/7Ps94F/JSgQu+EQTvF6ZlB92B0uZCffjUM+LMqeHp9sg5 t8cHzXxLBj4HR6KlxIuBKfujidNv2g3oheXN/X17aAdwJbrQyRaWMMh88YFhgQ== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1787673684; a=rsa-sha256; cv=none; b=BvQmKBG0OIl2aLupsZemTpLcnIBzfFRZ8VqmYoYZji28TZDxHqGC1JH52B+IL6JGGzH22r ZK7UXSyCBE/M4ms3gjdj2P7yXEq0bAhCOl2GPDcfernHb7fvLkCfu24aOgS6teo/a3HtKX LhSHaq/CMXq5WMYeTsudOyVt7B5/jE69nLPtzijrSdo/R7afQ89o1SREuo8jELt/Cwz7BB 93sMz9NZEkNfsoxY3bYmTOa07E50QHhCI57MHXiAYNOI5K9ryFWPPaX6SvH0lhH4aF/Asu 702xxGz6SQgDDhz1N+k8evpwvfiMHwQmgNmD2AC1kvdjIuO633fFnW4v9T3cVA== ARC-Authentication-Results: i=1; mx1.freebsd.org; none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1787673684; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=CE+reyvEJ2gNL+2ODCliJydtj6eQsgkA3PJRG7f/d+c=; b=hhwwHLR7fG36nWon64w5O3rWjE63LAA7KO1Ly2xGxlFB4FW8+LMgdkpwDy+jmEtE9a/fss 6qUyQh7rx7bhHZLM3x/ZuBW29GdRBCdQLs7l5/QDIeGAXdXdSuxWAUz94ajpTtWbe8DBJh WwLi0tMXqk0ujTotf7kw8D6jtNvKPJ34+JohhrHzEiPiuBmhNZxD/GXp7ID+PmKgIReycp CjxgbX4z6L1OBCz1R6RPan8NrBvZj0ttYhaebXlmEU1hJ82+qCC3+7XZHv4kyPJGR/Aqf8 eRDOKEbuj6W0Fwg+amUcFONtMKVY30BBptdEN6IzV2SfRqAw71/iJceC258IsA== Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) by mxrelay.nyi.freebsd.org (Postfix) with ESMTP id 4hTsw42l1VzyNG for ; Tue, 25 Aug 2026 16:01:24 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from git (uid 1279) (envelope-from git@FreeBSD.org) id 321f2 by gitrepo.freebsd.org (DragonFly Mail Agent v0.13+ on gitrepo.freebsd.org); Tue, 25 Aug 2026 16:01:24 +0000 To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org From: Mark Johnston Subject: git: 97b7439e3b06 - releng/15.1 - cred: Fix group_is_primary() List-Id: Commit messages for all branches of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-all List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: dev-commits-src-all@freebsd.org Sender: owner-dev-commits-src-all@FreeBSD.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: markj X-Git-Repository: src X-Git-Refname: refs/heads/releng/15.1 X-Git-Reftype: branch X-Git-Commit: 97b7439e3b060d350cbd85321dd7e315907f366a Auto-Submitted: auto-generated Date: Tue, 25 Aug 2026 16:01:24 +0000 Message-Id: <6a8dbc54.321f2.170a86f3@gitrepo.freebsd.org> The branch releng/15.1 has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=97b7439e3b060d350cbd85321dd7e315907f366a commit 97b7439e3b060d350cbd85321dd7e315907f366a Author: Mark Johnston AuthorDate: 2026-08-24 18:13:29 +0000 Commit: Mark Johnston CommitDate: 2026-08-24 19:34:13 +0000 cred: Fix group_is_primary() This helper wasn't updated in commit be1f7435ef21, so in reality it was testing whether "gid" is the first supplemental group. If a user doesn't belong to a supplementary group, then it's testing an uninitialized slot; since ucreds are allocated with M_ZERO, this typically means that we're testing gid == 0. group_is_primary() has exactly one use, in mac_do. There, it's used to determine whether to keep the caller's current primary groups. This means that a rule such as gid=0>uid=0 will permit any credential with no supplementary groups. I believe this is mostly exploitable by daemons which have explicitly dropped privileges and called setgroups(0, NULL); logged in users will have a non-empty supplementary group list by virtue of having gone through initgroups(3). Fix group_is_primary(), and add a regression test. Approved by: so Security: FreeBSD-SA-26:59.mac_do Security: CVE-2026-58092 Reported by: Hazley Samsudin of GovTech CSG Fixes: be1f7435ef21 ("kern: start tracking cr_gid outside of cr_groups[]") Reviewed by: olce, kevans Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D59051 --- sys/sys/ucred.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/sys/sys/ucred.h b/sys/sys/ucred.h index 4bf48a5e4b87..19b45a5541a7 100644 --- a/sys/sys/ucred.h +++ b/sys/sys/ucred.h @@ -267,7 +267,7 @@ bool cr_xids_subset(struct ucred *active_cred, struct ucred *obj_cred); static inline bool group_is_primary(const gid_t gid, const struct ucred *const cred) { - return (gid == cred->cr_groups[0] || gid == cred->cr_rgid || + return (gid == cred->cr_gid || gid == cred->cr_rgid || gid == cred->cr_svgid); } bool group_is_supplementary(const gid_t gid, const struct ucred *const cred);