From patchwork Mon Feb 3 10:28:08 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Brodsky X-Patchwork-Id: 13957241 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0B2BDC02192 for ; Mon, 3 Feb 2025 10:29:33 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 8E1ED280015; Mon, 3 Feb 2025 05:29:32 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 8913328000E; Mon, 3 Feb 2025 05:29:32 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 73357280015; Mon, 3 Feb 2025 05:29:32 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 50E9128000E for ; Mon, 3 Feb 2025 05:29:32 -0500 (EST) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 2E43AA2641 for ; Mon, 3 Feb 2025 10:28:58 +0000 (UTC) X-FDA: 83078260398.04.42FBE5C Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf05.hostedemail.com (Postfix) with ESMTP id 8CC66100002 for ; Mon, 3 Feb 2025 10:28:56 +0000 (UTC) Authentication-Results: imf05.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf05.hostedemail.com: domain of kevin.brodsky@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=kevin.brodsky@arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1738578536; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=VjrjF09VQnxDeNYh4e1Ha75V6UufRCaFP71EexFz7fY=; b=SwWZmEl0/j1+2z5Ks5x5bKtwbrKkSUMbULt573k/uKc1YCrjpqnPVcSQ/HJB4tuvZag9iD H7wXtMnV6kpeS8MASF2umdjo7wzv+Nuo/X3rsJB1ry4QEBkxkjE216WlEjOVTVwevulFT6 3GVo8+Kg8m4MDAoynUXqvXJZ3j0pkmk= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1738578536; a=rsa-sha256; cv=none; b=IsHNiQOvA53zA75XzCoeMR2CwD7Xe0NRvIXHp9iOZ27omnNJdijBinT1pOIs7qkQiIStw+ K5LnEroI7Hr9iBG6B46ucKI7BKvETHFq93CLZvFUyJMXEH/HITcVrhTqkYG7sV7begE0q1 JmamnxVb6POsS/MK1cuDFs4yuZ/m2sk= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf05.hostedemail.com: domain of kevin.brodsky@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=kevin.brodsky@arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 480031BC0; Mon, 3 Feb 2025 02:29:20 -0800 (PST) Received: from e123572-lin.arm.com (e123572-lin.cambridge.arm.com [10.1.194.54]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 196943F63F; Mon, 3 Feb 2025 02:28:51 -0800 (PST) From: Kevin Brodsky To: linux-hardening@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Kevin Brodsky , Andrew Morton , Mark Brown , Catalin Marinas , Dave Hansen , David Howells , "Eric W. Biederman" , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Andy Lutomirski , Marc Zyngier , Peter Zijlstra , Pierre Langlois , Quentin Perret , "Mike Rapoport (IBM)" , Ryan Roberts , Thomas Gleixner , Will Deacon , Matthew Wilcox , Qi Zheng , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, x86@kernel.org Subject: [RFC PATCH 7/8] fs: Protect creds installed by override_creds() Date: Mon, 3 Feb 2025 10:28:08 +0000 Message-ID: <20250203102809.1223255-8-kevin.brodsky@arm.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20250203102809.1223255-1-kevin.brodsky@arm.com> References: <20250203102809.1223255-1-kevin.brodsky@arm.com> MIME-Version: 1.0 X-Stat-Signature: 8fe3ae394qfs96k8hmx48bwz5gt48gmg X-Rspam-User: X-Rspamd-Queue-Id: 8CC66100002 X-Rspamd-Server: rspam03 X-HE-Tag: 1738578536-802863 X-HE-Meta: U2FsdGVkX1/+xzJ6jwpZ/faauB3uXDnV1xY/s0P16x/eA/aNVbe9JA2Aa51Mqs2yfhtHL5W/yUw8S/Bj+Sif9zkOcCrFsrDLFnV6mH0ucI+EJ4qeqXiAm/GU+h/UxERv8kZKtsifmkKGg544YW7Ks8GDuj9crtp2VnX3N7OXiCwE8hGSO6Rn4P6EveHMZ78DuafTuxLLm0tJXYXSgyUCrcRKmqMrsvEYX1XkboJpOgJ/OCAm86YOK+/lF7rp9+5rPAxHeo8Ap8uSCqvJMWE3pXBUuhbBCtWZIwhzDqnSIm4+qjthluvMSw9/eJQIg+21NPFAD0BRIyXQXTgsYrChXY+RG5e6lCWssMuApHs7ybvnmKPdFmlD6DCbpCZjfFn1HUfNwffbWp3zIwVNYsudjr2JZ49duinFwidrS1FzDbMh/NJnAEDvk/VePlfEUIX5GuwUvKJV/plnKK/sbIW/xGckgOYHYxerzJApvsfjr6J3LmMNyWgB+sKOgDt8vO7OpTZ3gv9mECrljOQ3Xr3nS1+ilxPP1zoQpddD/pAb9gzkjxjB+dB1/ygbRY0Rq3mor6RVgqdC9vZP+SimD4j50wcS3bTpxTPPbbopS/P8kHOTFElh5vtGL/90z6WeWibE3D3IUo0vXosgfoC8xSHrmvG8SpZvZjHqOZGyXlfKI7Eg9j0eGFzFRJrgW/JobgcmWcq0nNzIdUUbAZmXVzVtChXoRwAnQ7LhEXMpM2nAb2Gza+TZJogaPsChOChFURe7A/9iueUHuLjw2pn74fmTcz4Y1hE4zVoX+GuoHJ23Hrxt/Y69AGUG1X7g5Ar/IfdhOP4XpQmBGRMfI71aZJaxLbXGwS3Uftg7O+8fvowUQUN5pIIr7G+cJjIDkjIBiFL0PNA753BUpjPQkojdz8oL8+jaFUMIvWgmLuLisFq9n49Pp/JYBCX0bPU1NpA5UCZvA8vITEcErcaUecziHKm X+vY8JFm IfBQg/jzvbadeKeoqHZ6zeFKOcFLPGd+sQCXQlLbSeDzPHZScCP9Eh97AXapbBnT8BCe335IhMlOeV5kls66Fou69abmWBbMN1w1LnE6jraNKvPYQXb0TGLV1K5hE/Y3wZ7SdUp5gwhSyjCsWm3PBK7NOGcBPiUl1Er2BbVsCoR0dxKNoyS9QSUEYz0gJmhU9BwCfbxVGa4s56uc= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: The kpkeys_hardened_cred feature, when enabled, automatically protects credentials installed by commit_creds(). However, because override_creds() does not consume its argument, it is up to its callers to protect the credentials before calling override_creds(). This is done by calling protect_creds(), moving the credentials to a protected memory location. In some cases, the credentials returned by prepare_creds() are passed to override_creds() as-is. In such situation where write access to the credentials is not needed, prepare_protected_creds() is used to avoid the copy incurred by a separate call to protect_creds(). This patch covers the main users of override_creds(), but it is not comprehensive. This patch is a no-op if kpkeys_hardened_cred isn't enabled. Signed-off-by: Kevin Brodsky --- fs/aio.c | 2 +- fs/fuse/passthrough.c | 2 +- fs/nfs/nfs4idmap.c | 2 +- fs/nfsd/auth.c | 2 +- fs/nfsd/nfs4recover.c | 2 +- fs/nfsd/nfsfh.c | 2 +- fs/open.c | 2 +- fs/overlayfs/dir.c | 2 +- fs/overlayfs/super.c | 2 +- 9 files changed, 9 insertions(+), 9 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index 7b976b564cfc..ab9f4c8d778a 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -1657,7 +1657,7 @@ static int aio_fsync(struct fsync_iocb *req, const struct iocb *iocb, if (unlikely(!req->file->f_op->fsync)) return -EINVAL; - req->creds = prepare_creds(); + req->creds = prepare_protected_creds(); if (!req->creds) return -ENOMEM; diff --git a/fs/fuse/passthrough.c b/fs/fuse/passthrough.c index 607ef735ad4a..4451651b1e51 100644 --- a/fs/fuse/passthrough.c +++ b/fs/fuse/passthrough.c @@ -248,7 +248,7 @@ int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map) goto out_fput; fb->file = file; - fb->cred = prepare_creds(); + fb->cred = prepare_protected_creds(); refcount_set(&fb->count, 1); res = fuse_backing_id_alloc(fc, fb); diff --git a/fs/nfs/nfs4idmap.c b/fs/nfs/nfs4idmap.c index 25a7c771cfd8..6ff25dd5c2fb 100644 --- a/fs/nfs/nfs4idmap.c +++ b/fs/nfs/nfs4idmap.c @@ -228,7 +228,7 @@ int nfs_idmap_init(void) set_bit(KEY_FLAG_ROOT_CAN_CLEAR, &keyring->flags); cred->thread_keyring = keyring; cred->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING; - id_resolver_cache = cred; + id_resolver_cache = protect_creds(cred); return 0; failed_reg_legacy: diff --git a/fs/nfsd/auth.c b/fs/nfsd/auth.c index 4dc327e02456..09b377a97147 100644 --- a/fs/nfsd/auth.c +++ b/fs/nfsd/auth.c @@ -79,7 +79,7 @@ int nfsd_setuser(struct svc_cred *cred, struct svc_export *exp) else new->cap_effective = cap_raise_nfsd_set(new->cap_effective, new->cap_permitted); - put_cred(override_creds(new)); + put_cred(override_creds(protect_creds(new))); return 0; oom: diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c index 28f4d5311c40..095664648103 100644 --- a/fs/nfsd/nfs4recover.c +++ b/fs/nfsd/nfs4recover.c @@ -81,7 +81,7 @@ nfs4_save_creds(const struct cred **original_creds) new->fsuid = GLOBAL_ROOT_UID; new->fsgid = GLOBAL_ROOT_GID; - *original_creds = override_creds(new); + *original_creds = override_creds(protect_creds(new)); return 0; } diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c index 32019751a41e..d64d23e9357e 100644 --- a/fs/nfsd/nfsfh.c +++ b/fs/nfsd/nfsfh.c @@ -221,7 +221,7 @@ static __be32 nfsd_set_fh_dentry(struct svc_rqst *rqstp, struct net *net, new->cap_effective = cap_raise_nfsd_set(new->cap_effective, new->cap_permitted); - put_cred(override_creds(new)); + put_cred(override_creds(protect_creds(new))); } else { error = nfsd_setuser_and_check_port(rqstp, cred, exp); if (error) diff --git a/fs/open.c b/fs/open.c index 932e5a6de63b..3b5331b7c0f0 100644 --- a/fs/open.c +++ b/fs/open.c @@ -457,7 +457,7 @@ static const struct cred *access_override_creds(void) * freeing. */ override_cred->non_rcu = 1; - return override_creds(override_cred); + return override_creds(protect_creds(override_cred)); } static long do_faccessat(int dfd, const char __user *filename, int mode, int flags) diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c index c9993ff66fc2..943ec4300ddb 100644 --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -580,7 +580,7 @@ static const struct cred *ovl_setup_cred_for_create(struct dentry *dentry, * We must be called with creator creds already, otherwise we risk * leaking creds. */ - old_cred = override_creds(override_cred); + old_cred = override_creds(protect_creds(override_cred)); WARN_ON_ONCE(old_cred != ovl_creds(dentry->d_sb)); return override_cred; diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 86ae6f6da36b..3489a62c5d8a 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -1318,7 +1318,7 @@ int ovl_fill_super(struct super_block *sb, struct fs_context *fc) sb->s_d_op = &ovl_dentry_operations; err = -ENOMEM; - ofs->creator_cred = cred = prepare_creds(); + ofs->creator_cred = cred = prepare_protected_creds(); if (!cred) goto out_err;