From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lists.trustedfirmware.org (lists.trustedfirmware.org [18.214.241.189]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 96E61606A31B for ; Thu, 5 Nov 2026 11:14:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.trustedfirmware.org header.i=@lists.trustedfirmware.org header.a=rsa-sha256 header.s=2024 header.b=DmMXSh8S; dkim=fail reason="signature verification failed" (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=WAbXpW5G Received: from lists.trustedfirmware.org (localhost [127.0.0.1]) by lists.trustedfirmware.org (Postfix) with ESMTP id DFDF745477 for ; Thu, 5 Nov 2026 11:14:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=lists.trustedfirmware.org; s=2024; t=1793877280; bh=XskcVFVajMJ3lCtnLA33HB++4MDmGwkBHRS6+TTKIX8=; h=Subject:To:In-Reply-To:References:Date:CC:List-Id:List-Archive: List-Help:List-Owner:List-Post:List-Subscribe:List-Unsubscribe: From:Reply-To:From; b=DmMXSh8SDc5vS7X+OU6DSwm6DDsbcHgQgPVDMjwAOAWMh8MktcwhzAw55BGfS93Xo z7ZEstHh0wZadi+sp9Ri5oBpVIH08d8abOs/Ox8h+U3yaA6WyvcZ2dN0Ucp/SYgBuX 1u7GkkcARB5E3i8A3oMhYQBhBKsHeVcq/wHBjrdqKL+bLUDtr3/eXkKorNvR8ACkyj O1QOU+YodP3V66UdWi1/bYkXyzxU+vcVTvE0xV0caRkKs/gYMbtjuZkaYTaWGpWDtG U0qUR7PRTrr4W1wjPCIDlJFNfQzMfgyBB/1UVbHrTlCw7sguly0MHcKHp4HwVCrgsU vju1NSkvN0JQA== Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by lists.trustedfirmware.org (Postfix) with ESMTPS id CB3E84549F for ; Thu, 5 Nov 2026 11:12:05 +0000 (UTC) Authentication-Results: lists.trustedfirmware.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=WAbXpW5G; dkim-atps=neutral Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 4F51D41FFD; Thu, 5 Nov 2026 11:12:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D3B671F000C1; Thu, 5 Nov 2026 11:12:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793877125; bh=A6Btm3+v+dnXqWTR2GX+hsLiVMvVrLHj5mxZiRv+uQA=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=WAbXpW5G+J81zpga2YkofDFAJr37p7VW0gGXFRU1+QCgzM/A2pZgHgznNZ2nCalqE Ia3JyUZPh6L8Rg/y+uDgpDdpHVkNXyzDJVU61C50bKdJpxk3QmFsmifPi+WacjV/XA QcdaQ2JwYWDZM/S9fBxO98d3uu84tMP2L3LX4JZ6BhPLw+JPH/18HgMzAJJzcMfDF3 tw4HNNjQMzFdjFhehxPRAgVYMCdqVn+EzZzkd0u3g2A/L89+VMUZrPX21d6cbm+Hxu OFZ2xzICDiinoYKDYRJ6cNwQKSRtQb9bUblJfArFReo7oJfCXLWSKUy3cXW4MihmdO KKFQUwanA6LGA== Message-ID: Subject: Re: [PATCH v4 7/8] selinux: Restrict dma-buf direct cgroup charging To: "Albert Esteve" , "Tejun Heo" , "Johannes Weiner" , =?utf-8?b?TWljaGFsIEtvdXRuw70=?= , "Jonathan Corbet" , "Shuah Khan" , "Sumit Semwal" , =?utf-8?b?Q2hyaXN0aWFuIEvDtm5pZw==?= , "Michal Hocko" , "Roman Gushchin" , "Shakeel Butt" , "Muchun Song" , "Andrew Morton" , "Benjamin Gaignard" , "Brian Starkey" , "John Stultz" , "T.J. Mercier" , "Christian Brauner" , "Paul Moore" , "James Morris" , "Serge E. Hallyn" , "Stephen Smalley" , "Shuah Khan" , "Randy Dunlap" , =?utf-8?b?T25kcmVqIE1vc27DocSNZWs=?= , "Jens Wiklander" , "Sumit Garg" In-Reply-To: <20261104-v2_20230123_tjmercier_google_com-v4-7-1819a017000b@redhat.com> References: <20261104-v2_20230123_tjmercier_google_com-v4-0-1819a017000b@redhat.com> <20261104-v2_20230123_tjmercier_google_com-v4-7-1819a017000b@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Thu, 05 Nov 2026 11:12:03 +0000 X-Rspamd-Action: no action X-Spamd-Result: default: False [-5.50 / 15.00]; WHITELIST_SPF_DKIM(-3.00)[kernel.org:d:+,kernel.org:s:+]; BAYES_HAM(-3.00)[99.99%]; DWL_DNSWL_MED(-2.00)[kernel.org:dkim]; MISSING_MIME_VERSION(2.00)[]; SUSPICIOUS_RECIPS(1.50)[]; DMARC_POLICY_ALLOW(-0.50)[kernel.org,quarantine]; R_SPF_ALLOW(-0.20)[+ip4:172.234.252.31:c]; R_DKIM_ALLOW(-0.20)[kernel.org:s=k20260515]; MIME_GOOD(-0.10)[text/plain]; REPLYTO_DN_EQ_FROM_DN(0.00)[]; RCVD_TLS_LAST(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FREEMAIL_TO(0.00)[redhat.com,kernel.org,cmpxchg.org,suse.com,lwn.net,linuxfoundation.org,linaro.org,amd.com,linux.dev,linux-foundation.org,collabora.com,arm.com,google.com,paul-moore.com,namei.org,hallyn.com,gmail.com,infradead.org]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; RCPT_COUNT_TWELVE(0.00)[33]; REPLYTO_DOM_NEQ_FROM_DOM(0.00)[]; DKIM_TRACE(0.00)[kernel.org:+]; REPLYTO_DOM_NEQ_TO_DOM(0.00)[]; DNSWL_BLOCKED(0.00)[172.234.252.31:from]; ALIAS_RESOLVED(0.00)[]; TO_MATCH_ENVRCPT_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; TO_DN_SOME(0.00)[]; NEURAL_HAM(-0.00)[-1.000]; RCVD_VIA_SMTP_AUTH(0.00)[]; MISSING_XM_UA(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; FROM_NO_DN(0.00)[]; ASN(0.00)[asn:63949, ipnet:172.234.224.0/19, country:SG]; HAS_REPLYTO(0.00)[sashiko-reviews@lists.linux.dev] X-Rspamd-Server: lists.trustedfirmware.org X-Rspamd-Queue-Id: CB3E84549F X-Spamd-Bar: ----- Message-ID-Hash: QPYET2LPA5VQCXU6T5XPVNYKLOK2ICIG X-Message-ID-Hash: QPYET2LPA5VQCXU6T5XPVNYKLOK2ICIG X-MailFrom: sashiko-bot@kernel.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-op-tee.lists.trustedfirmware.org-0; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: dri-devel@lists.freedesktop.org, linux-mm@kvack.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, op-tee@lists.trustedfirmware.org, media-ci@linuxtv.org X-Mailman-Version: 3.3.5 Precedence: list List-Id: Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: From: sashiko-bot--- via OP-TEE Reply-To: sashiko-reviews@lists.linux.dev, sashiko-bot@kernel.org X-Spam-Status: No, score=-11.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=unavailable autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 X-Archived-By: Thank you for your contribution! Sashiko AI review found 2 potential issue(= s) to consider: - [High] selinux: selinux_dma_buf_charge_cgroup() bypasses check on genfsco= n cgroups - [Medium] selinux: one-off dma_buf charge_cgroup lacks broader cgroup cont= rol design -- commit d0dd0ed1dd84ec5c8f4de9a298a749d83668b53e Author: Albert Esteve selinux: Restrict dma-buf direct cgroup charging This commit implements the selinux_dma_buf_charge_cgroup() hook and adds the charge_cgroup permission to the dma_buf security class to restrict which processes can charge dma-buf memory to a target cgroup. > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > index 8f39d91eabc97..2f99eaa910af4 100644 > --- a/security/selinux/hooks.c > +++ b/security/selinux/hooks.c > @@ -2210,6 +2210,40 @@ static int selinux_dma_buf_charge_task(const struc= t cred *from, const struct cre > SECCLASS_DMA_BUF, DMA_BUF__CHARGE_TASK, NULL); > } > =20 > +#ifdef CONFIG_CGROUPS > +static int selinux_dma_buf_charge_cgroup(const struct cred *cred, struct= cgroup *cgrp) > +{ > + u32 cgrp_sid, clen; > + int rc; > + char *context; > + > + rc =3D kernfs_xattr_get(cgrp->kn, XATTR_NAME_SELINUX, NULL, 0); > + if (rc =3D=3D -ENODATA) > + return 0; [Severity: High] As reported by Sashiko on v3 [1], in security/selinux/hooks.c, does returni= ng 0 in selinux_dma_buf_charge_cgroup() when kernfs_xattr_get() returns -ENODA= TA bypass the permission check for all default-labeled cgroups? When a process calls ioctl(DMA_HEAP_IOCTL_ALLOC) or ioctl(DMA_BUF_IOCTL_XFER_CHARGE) with a charge_fd referencing a cgroup directory, mem_cgroup_get_from_fd() invokes security_dma_buf_charge_cgroup() -> selinux_dma_buf_charge_cgroup(). In SELinux, cgroup and cgroup2 filesystems are configured with SE_SBGENFS | SE_SBGENFS_XATTR in selinux_set_mnt_opts() and obtain their default label (such as cgroup_t) from policy genfscon rules. When a cgroupfs VFS inode is initialized in inode_doinit_with_dentry(), SELinux computes the default SID via selinux_genfs_get_sid() and only uses kernfs xattrs as an optional override: security/selinux/hooks.c:inode_doinit_with_dentry() { ... rc =3D selinux_genfs_get_sid(dentry, sclass, sbsec->flags, &sid); if (rc) { dput(dentry); goto out; } if ((sbsec->flags & SE_SBGENFS_XATTR) && (inode->i_opflags & IOP_XATTR)) { rc =3D inode_doinit_use_xattr(inode, dentry, sid, &sid); ... } When no explicit setxattr() has been performed on the cgroup directory, inode_doinit_use_xattr() gets -ENODATA and falls back to def_sid in memory without writing any security.selinux xattr to cgrp->kn: security/selinux/hooks.c:inode_doinit_use_xattr() { ... if (rc < 0) { kfree(context); if (rc !=3D -ENODATA) { pr_warn("SELinux: %s: getxattr returned %d for dev=3D%s ino=3D%llu\n", __func__, -rc, inode->i_sb->s_id, inode->i_ino); return rc; } *sid =3D def_sid; return 0; } ... } Similarly, selinux_kernfs_init_security() sees -ENODATA on the parent node and returns 0 without setting an xattr on child cgroup nodes, and if the cgroup_seclabel policy capability is not enabled, security.selinux xattrs cannot be set on cgroup directories at all. Because kernfs_xattr_get(cgrp->kn, XATTR_NAME_SELINUX, NULL, 0) returns -ENODATA for every cgroup that has not been manually relabeled via setxattr(), won't selinux_dma_buf_charge_cgroup() skip avc_has_perm() for a= ll default-labeled cgroup_t cgroups and render policy rules like "allow allocator_app_t cgroup_t:dma_buf charge_cgroup;" ineffective? [ ... ] > diff --git a/security/selinux/include/classmap.h b/security/selinux/inclu= de/classmap.h > index b4ebedc6e4240..90d1e04c3d27c 100644 > --- a/security/selinux/include/classmap.h > +++ b/security/selinux/include/classmap.h > @@ -181,7 +181,7 @@ const struct security_class_mapping secclass_map[] = =3D { > { "user_namespace", { "create", NULL } }, > { "memfd_file", > { COMMON_FILE_PERMS, "execute_no_trans", "entrypoint", NULL } }, > - { "dma_buf", { "charge_task", NULL } }, > + { "dma_buf", { "charge_task", "charge_cgroup", NULL } }, [Severity: Medium] As reported by Paul Moore on RFC [2], in security/selinux/include/classmap.h (secclass_map) and security/selinux/hooks.c (selinux_dma_buf_charge_cgroup(= )), this adds a narrow dma_buf class permission for cgroup charging invoked from DMA_HEAP_IOCTL_ALLOC and DMA_BUF_IOCTL_XFER_CHARGE via mem_cgroup_get_from_fd() -> security_dma_buf_charge_cgroup(). Rather than introducing a one-off dma_buf cgroup charging permission, should this be part of a broader SELinux access control design covering existing cgroup control points so that the object class and permission model is consistent across cgroup operations? [1] https://lore.kernel.org/r/20261027-v2_20230123_tjmercier_google_com-v3-= 6-78d2c4cb8647@redhat.com [2] https://lore.kernel.org/r/16093a0278a6d7d1a0a8bc055c228bed@paul-moore.c= om --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261104-v2_2023012= 3_tjmercier_google_com-v4-0-1819a017000b@redhat.com?part=3D7