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 91F11345CC6; Tue, 16 Dec 2025 11:37:47 +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=1765885067; cv=none; b=nK4JKxSb/31O8MkAAj73qEJ/7k1ATc0eC85vf40RNUxmZJ2qXYGjsdgYHH0Mrt+3V7TNe01R33tw3M3jE42HJv89EH5QULD9jGP+hduuf7NBje1kAZmHtWm6y5UHNDZVHQsJiB1w6Oa2fr5Ycoy40XeUYz5uGFA0eIfRUHIMzIE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765885067; c=relaxed/simple; bh=+odUc76j0beUf0+h1Hr5v8IKSKs/eCf6LTwuE8eDA3w=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Ba/BulV98T9dD7T5dB+jk/UMhsc2R+vpzVqjenZQ1m7R9ZAN7qj1hTb1pqce9okq4bW/qExZS+W6QZ4cwThNjR++cUi01sH3R2ZPCw1sL7mviFUpIMAcaSKB4I443O6uDBlVrKzv5JoNmmT1Umygukf1D1rqjB4tDcbZrj/fYIU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=SLBC93MG; 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="SLBC93MG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0EB12C4CEF1; Tue, 16 Dec 2025 11:37:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1765885067; bh=+odUc76j0beUf0+h1Hr5v8IKSKs/eCf6LTwuE8eDA3w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SLBC93MGhIP/I4TO/bLiuzWgYA3lqdeAhHu73UaTLlNEBLhXuizLHB/k6naMQvtyj nYGSNASNYjn/1OLW0mwQX8ub92VnqTiuH7NiIiWvv5/zpVQ2q9IqeTYVh5HfNJH4ch JhUnghpdK3Pq4zcrD3Ml0vSiOWt4vh6evcFI8PxA= 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 6.17 006/507] smack: fix bug: unprivileged task can create labels Date: Tue, 16 Dec 2025 12:07:27 +0100 Message-ID: <20251216111345.760736506@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20251216111345.522190956@linuxfoundation.org> References: <20251216111345.522190956@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 6.17-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 30f20fef3331e..159ccc1d9847c 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