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 3380E1FC0F4; Mon, 13 Jan 2025 18:35:25 +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=1736793325; cv=none; b=dyxDn7bhxT9qyy77OD71BFJ56aWMLArdkEP/K2I251SpqBCg1+Iu/5iQATE2vnokPQL0UmmUlEFODB45XMrHcWXH60yKSUK4xI+1kXoF81p5ciY37ogg2dwHbOLmAcGAs9FXW9W7dh2KWzkgX3xoi2XTlHNaT4qnCE+WItrNymE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736793325; c=relaxed/simple; bh=BE+Y0XSeW8eoYlbqAzwQnaajnEIJVDMT7DuCgIXfWHg=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=F3HJzN9cREa2WrARHKcZyd6W61BckSac0ffMO0PJiRYFWF6YohfArHQRbJHfRHzMOauexODCeKKyBtxoEt2IvZxEHHlltco78OFSt2l0irVsJhNkS8kkJllhe6pUHh/Les/nNFnQ1tmwoIv1XxLk6OsoT5p7ovWDgIiTr8d06XA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Yxi21eIW; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Yxi21eIW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3BC8DC4CED6; Mon, 13 Jan 2025 18:35:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1736793325; bh=BE+Y0XSeW8eoYlbqAzwQnaajnEIJVDMT7DuCgIXfWHg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Yxi21eIWhZhuF2n/fNVmsvGVikEqtRje+UAT1m/cLCfiaOvxKR2IH0uvh+Eblp0DY owHRxOS4Z9eNHbxaEfqRLvgG9mO5U4qmjwKfZDBlLcQW4LBBf5UyiNyKlBe491YMlV DQoR6KU57hP1tNOpKhRr4XCz/v5rOBSyFZpk1SA1w6Xu2k3uEW9gSGFBcF1jTQHihq ullndUzwM8M96cB0gP7LFbIf4zESEw/HYcpAssk2spSVYbkk8mCeHFfO2yVYyLcbko SFYox8YKz08Xj1ClJjX4IpXu05JScYUTzizIiDwGOB2MHXPjeq/5mcfjVbzeFgcteg wAO/G8L9V//ZQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Max Kellermann , David Howells , Christian Brauner , Sasha Levin , netfs@lists.linux.dev Subject: [PATCH AUTOSEL 6.6 05/10] cachefiles: Parse the "secctx" immediately Date: Mon, 13 Jan 2025 13:35:06 -0500 Message-Id: <20250113183511.1783990-5-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250113183511.1783990-1-sashal@kernel.org> References: <20250113183511.1783990-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.6.71 Content-Transfer-Encoding: 8bit From: Max Kellermann [ Upstream commit e5a8b6446c0d370716f193771ccacf3260a57534 ] Instead of storing an opaque string, call security_secctx_to_secid() right in the "secctx" command handler and store only the numeric "secid". This eliminates an unnecessary string allocation and allows the daemon to receive errors when writing the "secctx" command instead of postponing the error to the "bind" command handler. For example, if the kernel was built without `CONFIG_SECURITY`, "bind" will return `EOPNOTSUPP`, but the daemon doesn't know why. With this patch, the "secctx" will instead return `EOPNOTSUPP` which is the right context for this error. This patch adds a boolean flag `have_secid` because I'm not sure if we can safely assume that zero is the special secid value for "not set". This appears to be true for SELinux, Smack and AppArmor, but since this attribute is not documented, I'm unable to derive a stable guarantee for that. Signed-off-by: Max Kellermann Signed-off-by: David Howells Link: https://lore.kernel.org/r/20241209141554.638708-1-max.kellermann@ionos.com/ Link: https://lore.kernel.org/r/20241213135013.2964079-6-dhowells@redhat.com Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin --- fs/cachefiles/daemon.c | 14 +++++++------- fs/cachefiles/internal.h | 3 ++- fs/cachefiles/security.c | 6 +++--- 3 files changed, 12 insertions(+), 11 deletions(-) diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c index 89b11336a836..1806bff8e59b 100644 --- a/fs/cachefiles/daemon.c +++ b/fs/cachefiles/daemon.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include #include @@ -576,7 +577,7 @@ static int cachefiles_daemon_dir(struct cachefiles_cache *cache, char *args) */ static int cachefiles_daemon_secctx(struct cachefiles_cache *cache, char *args) { - char *secctx; + int err; _enter(",%s", args); @@ -585,16 +586,16 @@ static int cachefiles_daemon_secctx(struct cachefiles_cache *cache, char *args) return -EINVAL; } - if (cache->secctx) { + if (cache->have_secid) { pr_err("Second security context specified\n"); return -EINVAL; } - secctx = kstrdup(args, GFP_KERNEL); - if (!secctx) - return -ENOMEM; + err = security_secctx_to_secid(args, strlen(args), &cache->secid); + if (err) + return err; - cache->secctx = secctx; + cache->have_secid = true; return 0; } @@ -820,7 +821,6 @@ static void cachefiles_daemon_unbind(struct cachefiles_cache *cache) put_cred(cache->cache_cred); kfree(cache->rootdirname); - kfree(cache->secctx); kfree(cache->tag); _leave(""); diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h index 111ad6ecd4ba..4421a12960a6 100644 --- a/fs/cachefiles/internal.h +++ b/fs/cachefiles/internal.h @@ -122,7 +122,6 @@ struct cachefiles_cache { #define CACHEFILES_STATE_CHANGED 3 /* T if state changed (poll trigger) */ #define CACHEFILES_ONDEMAND_MODE 4 /* T if in on-demand read mode */ char *rootdirname; /* name of cache root directory */ - char *secctx; /* LSM security context */ char *tag; /* cache binding tag */ refcount_t unbind_pincount;/* refcount to do daemon unbind */ struct xarray reqs; /* xarray of pending on-demand requests */ @@ -130,6 +129,8 @@ struct cachefiles_cache { struct xarray ondemand_ids; /* xarray for ondemand_id allocation */ u32 ondemand_id_next; u32 msg_id_next; + u32 secid; /* LSM security id */ + bool have_secid; /* whether "secid" was set */ }; static inline bool cachefiles_in_ondemand_mode(struct cachefiles_cache *cache) diff --git a/fs/cachefiles/security.c b/fs/cachefiles/security.c index fe777164f1d8..fc6611886b3b 100644 --- a/fs/cachefiles/security.c +++ b/fs/cachefiles/security.c @@ -18,7 +18,7 @@ int cachefiles_get_security_ID(struct cachefiles_cache *cache) struct cred *new; int ret; - _enter("{%s}", cache->secctx); + _enter("{%u}", cache->have_secid ? cache->secid : 0); new = prepare_kernel_cred(current); if (!new) { @@ -26,8 +26,8 @@ int cachefiles_get_security_ID(struct cachefiles_cache *cache) goto error; } - if (cache->secctx) { - ret = set_security_override_from_ctx(new, cache->secctx); + if (cache->have_secid) { + ret = set_security_override(new, cache->secid); if (ret < 0) { put_cred(new); pr_err("Security denies permission to nominate security context: error %d\n", -- 2.39.5