From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1642235CB96; Tue, 16 Dec 2025 12:06:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765886771; cv=none; b=Ln99MixGBvRlICjw0zjpVvrdSBoD5YboBJ+yT4a2WyqHFMX/3hj4Vf5jPWgQKMkJIyWV+cMDKPW8s5YS6PL5psfTAaRmT6sTJiFebicmDazJj15l6tSpdruJ8dMeKIfEJbNJIHD6SKzfMs76OGL7V28Vhapv/sXjnQ5HxZchF8o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765886771; c=relaxed/simple; bh=+nT3JZLj0tmlgD0zkLFFD+rOafgRv590qqmAbb0RsL0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jTpFR8Iqp4eSXkSwIdczUNX+A9DkaBhAqx67X6msLrkKyIz+xzJyYQw9zTR2RipZ7hdsOMRLLj6J3VPXPbPyP868qcpHzf+bmMNW4NaakYOMg33L5YZ5MTYjR6zga344+RvUaMyJ5oJh9JMnH/e4uJnCxhSFgBnRU/tevKlnzIM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=pS2U73Za; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="pS2U73Za" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 42C60C4CEF5; Tue, 16 Dec 2025 12:06:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1765886770; bh=+nT3JZLj0tmlgD0zkLFFD+rOafgRv590qqmAbb0RsL0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pS2U73ZaAI+FlPvVBm1yd/f/cL3U+8RB6PQCTT8uSai6jQt7mq2nVMW8Y6snSVVXa T6ncheVGwpn+WzrmWovVKFMgr9p9OsbYAaQNztocvIf2PmgZunMp5JBbw67/1ztbZ1 4NiFv7zTZKQhnQYHRD1ogS5xgYMkyszwUq4A4NQE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Konstantin Andreev , Casey Schaufler , Sasha Levin Subject: [PATCH 6.18 006/614] smack: fix bug: unprivileged task can create labels Date: Tue, 16 Dec 2025 12:06:13 +0100 Message-ID: <20251216111401.524638294@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20251216111401.280873349@linuxfoundation.org> References: <20251216111401.280873349@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Konstantin Andreev [ Upstream commit c147e13ea7fe9f118f8c9ba5e96cbd644b00d6b3 ] If an unprivileged task is allowed to relabel itself (/smack/relabel-self is not empty), it can freely create new labels by writing their names into own /proc/PID/attr/smack/current This occurs because do_setattr() imports the provided label in advance, before checking "relabel-self" list. This change ensures that the "relabel-self" list is checked before importing the label. Fixes: 38416e53936e ("Smack: limited capability for changing process label") Signed-off-by: Konstantin Andreev Signed-off-by: Casey Schaufler Signed-off-by: Sasha Levin --- security/smack/smack_lsm.c | 41 +++++++++++++++++++++++++------------- 1 file changed, 27 insertions(+), 14 deletions(-) diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index d16453801a79e..07dbc4cd303a7 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -3778,8 +3778,8 @@ static int do_setattr(u64 attr, void *value, size_t size) struct task_smack *tsp = smack_cred(current_cred()); struct cred *new; struct smack_known *skp; - struct smack_known_list_elem *sklep; - int rc; + char *labelstr; + int rc = 0; if (!smack_privileged(CAP_MAC_ADMIN) && list_empty(&tsp->smk_relabel)) return -EPERM; @@ -3790,28 +3790,41 @@ static int do_setattr(u64 attr, void *value, size_t size) if (attr != LSM_ATTR_CURRENT) return -EOPNOTSUPP; - skp = smk_import_entry(value, size); - if (IS_ERR(skp)) - return PTR_ERR(skp); + labelstr = smk_parse_smack(value, size); + if (IS_ERR(labelstr)) + return PTR_ERR(labelstr); /* * No process is ever allowed the web ("@") label * and the star ("*") label. */ - if (skp == &smack_known_web || skp == &smack_known_star) - return -EINVAL; + if (labelstr[1] == '\0' /* '@', '*' */) { + const char c = labelstr[0]; + + if (c == *smack_known_web.smk_known || + c == *smack_known_star.smk_known) { + rc = -EPERM; + goto free_labelstr; + } + } if (!smack_privileged(CAP_MAC_ADMIN)) { - rc = -EPERM; + const struct smack_known_list_elem *sklep; list_for_each_entry(sklep, &tsp->smk_relabel, list) - if (sklep->smk_label == skp) { - rc = 0; - break; - } - if (rc) - return rc; + if (strcmp(sklep->smk_label->smk_known, labelstr) == 0) + goto free_labelstr; + rc = -EPERM; } +free_labelstr: + kfree(labelstr); + if (rc) + return -EPERM; + + skp = smk_import_entry(value, size); + if (IS_ERR(skp)) + return PTR_ERR(skp); + new = prepare_creds(); if (new == NULL) return -ENOMEM; -- 2.51.0