From patchwork Tue Aug 8 11:34:20 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 13346559 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 93EB5C04FE0 for ; Tue, 8 Aug 2023 17:47:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229998AbjHHRrN (ORCPT ); Tue, 8 Aug 2023 13:47:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48422 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234894AbjHHRpu (ORCPT ); Tue, 8 Aug 2023 13:45:50 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 332EC25EC5; Tue, 8 Aug 2023 09:20:50 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C26AF624E4; Tue, 8 Aug 2023 11:34:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9DE6DC433C7; Tue, 8 Aug 2023 11:34:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1691494466; bh=jT5jlcg2gdDwL4+StPeX7zJK5A+Ru5LuAg/g9n75i/U=; h=From:Date:Subject:To:Cc:From; b=GCIxZSgjsOIaicABBTDeZGuDdV5hQUKX9WKXki8rIZ2oOo1WCeeH4bn0bPjurTu/Z lWJHsWGHCPYTXPBcWhM409AG7ECGlko/ZCtGEhXngpuHAhezkbWBWQNpJPRHx/qoh9 kDDaw9aEn/t1lRhS13+u2Eq56Yt4FEE88ghA/ScjJ2OY2hUppYMPcvMrvguFcBMFWH ZdIiJgpBgjl92H0dPeOQBEi2l4qoA0EOoC/kkeez1MS0wYWdr+9+0UKs31km08ixN2 BE25hX3+uHywV1HHJZ1aEPnJnJBTVbXpnrU1hzpGHejc9BflzsqdUDYPejmD55IGUj GlGKZTn/skjLA== From: Jeff Layton Date: Tue, 08 Aug 2023 07:34:20 -0400 Subject: [PATCH v9] vfs, security: Fix automount superblock LSM init problem, preventing NFS sb sharing MIME-Version: 1.0 Message-Id: <20230808-master-v9-1-e0ecde888221@kernel.org> X-B4-Tracking: v=1; b=H4sIADso0mQC/2XOTU7DMBAF4KtUXmPLHvwzZtV7IBahmSZWaVyNT aCqcnecLKqiLp8035t3E4U4URFvu5tgmlNJeWohvuzEYeymgWTqWxag4VWjBnnuSiWWLYCOmrD 3UbTjC9Mx/W5F7x8tHzmfZR2Zuo0b71EHdD44VBADeA3KWBNcNADaGA86QACjSh1S3f90XMc8q AvnwzVPKvOgvk/rozGVmvm6DZ79+u5p2+ylkdb1FiFG4/FzfyKe6GttEeu4OTw6e3ehucbIom1 rIj45fHTh7nB1lsBGF93R6H9uWZY/EOnj7GYBAAA= To: Alexander Viro , Christian Brauner , Trond Myklebust , Anna Schumaker , Paul Moore , James Morris , "Serge E. Hallyn" , Stephen Smalley , Eric Paris , Casey Schaufler , David Howells , Scott Mayhew Cc: Stephen Smalley , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, Jeff Layton X-Mailer: b4 0.12.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=10673; i=jlayton@kernel.org; h=from:subject:message-id; bh=3wamLJ1ZUQ6bMvCdgxc+3ktMYaNUWu2MFno2+xMRdvo=; b=owEBbQKS/ZANAwAIAQAOaEEZVoIVAcsmYgBk0ihAaM4Cy7BUOnhJtMipuA2vB7LDwWtdMTodb 37CD1VGBc+JAjMEAAEIAB0WIQRLwNeyRHGyoYTq9dMADmhBGVaCFQUCZNIoQAAKCRAADmhBGVaC FQ1YEADA9hlu16r8PP9DIZ3lEGF9ETvCSNiHCkPXJxZcUCSa//dXqUHxieB1GeICxj0UVq4N1x5 BmcuJQHQfFwqNVEiYT8ynuaHIQp7ufEemlGjr4xRtFg0lLZ295tdj5kcwCGJFTk8mDlcb7Q4M0Y paw1ULQnvdBaYMd8JzrN1VzCZnMvmLcNTZbcxe/h9pMw9xEzu1Sgq9tceObZgQixaM7vS0bgqXl O/YhHoBYH/yvntZkC95/eoj5+IvNIsaivn27qvZljRNdsLdUXbgQ2RhkPCgVuWujnNrZoxNUpS2 cIDGUv63TP54mnYVBzOu8UsiZcSfhyvgFJWFYwAtdrTGfC2SgUYieH5guFaIoTkj6Omany7Zt6/ X7RjLdPNnNHrBpFi8xdxnkebDaJ86XUmtp7MIQm+qrJ0r/QBmIqIaOBqQvM/JDsWLdzjhh9QkA2 wmPrs3WXqoxFbl6W1e4+/J6VRKhDm5Mxulm2oUFk1WbvCxTKEqPxv7RxH5V9sx1/pPpb0Vqo1Ne SMHBAQB8xUhbSE6Z3NiP3Q0q/XZbRl52FZFj4l3WacQRqO3uB1ebs4Ecvdj5u0Qzv9s6mxBiuoy niBGWiDzKcggYZnC06vTMIolRAG4a/Pn91Iygc3DVxxhyfavn+rVDCzLv/vptDPZIpzUIZVTd1e hk/lWvPq02KuXhA== X-Developer-Key: i=jlayton@kernel.org; a=openpgp; fpr=4BC0D7B24471B2A184EAF5D3000E684119568215 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: David Howells When NFS superblocks are created by automounting, their LSM parameters aren't set in the fs_context struct prior to sget_fc() being called, leading to failure to match existing superblocks. This bug leads to messages like the following appearing in dmesg when fscache is enabled: NFS: Cache volume key already in use (nfs,4.2,2,108,106a8c0,1,,,,100000,100000,2ee,3a98,1d4c,3a98,1) Fix this by adding a new LSM hook to load fc->security for submount creation. Signed-off-by: David Howells Signed-off-by: Jeff Layton Fixes: 9bc61ab18b1d ("vfs: Introduce fs_context, switch vfs_kern_mount() to it.") Fixes: 779df6a5480f ("NFS: Ensure security label is set for root inode) Tested-by: Jeff Layton Reviewed-by: Jeff Layton Acked-by: Casey Schaufler Acked-by: "Christian Brauner (Microsoft)" Link: https://lore.kernel.org/r/165962680944.3334508.6610023900349142034.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/165962729225.3357250.14350728846471527137.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/165970659095.2812394.6868894171102318796.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/166133579016.3678898.6283195019480567275.stgit@warthog.procyon.org.uk/ # v4 Link: https://lore.kernel.org/r/217595.1662033775@warthog.procyon.org.uk/ # v5 Acked-by: Paul Moore --- ver #2) - Added Smack support - Made LSM parameter extraction dependent on reference != NULL. ver #3) - Made LSM parameter extraction dependent on fc->purpose == FS_CONTEXT_FOR_SUBMOUNT. Shouldn't happen on FOR_RECONFIGURE. ver #4) - When doing a FOR_SUBMOUNT mount, don't set the root label in SELinux or Smack. ver #5) - Removed unused variable. - Only allocate smack_mnt_opts if we're dealing with a submount. ver #6) - Rebase onto v6.5.0-rc4 - Link to v6: https://lore.kernel.org/r/20230802-master-v6-1-45d48299168b@kernel.org ver #7) - Drop lsm_set boolean - Link to v7: https://lore.kernel.org/r/20230804-master-v7-1-5d4e48407298@kernel.org ver #8) - Remove spurious semicolon in smack_fs_context_init - Make fs_context_init take a superblock as reference instead of dentry - WARN_ON_ONCE's when fc->purpose != FS_CONTEXT_FOR_SUBMOUNT - Call the security hook from fs_context_for_submount instead of alloc_fs_context - Link to v8: https://lore.kernel.org/r/20230807-master-v8-1-54e249595f10@kernel.org ver #9) - rename *_fs_context_init to *_fs_context_submount - remove checks for FS_CONTEXT_FOR_SUBMOUNT and NULL reference pointers - fix prototype on smack_fs_context_submount --- fs/fs_context.c | 23 ++++++++++++++++++- include/linux/lsm_hook_defs.h | 1 + include/linux/security.h | 6 +++++ security/security.c | 14 ++++++++++++ security/selinux/hooks.c | 22 +++++++++++++++++++ security/smack/smack_lsm.c | 51 +++++++++++++++++++++++++++++++++++++++++++ 6 files changed, 116 insertions(+), 1 deletion(-) --- base-commit: 52a93d39b17dc7eb98b6aa3edb93943248e03b2f change-id: 20230802-master-3082090e8d69 Best regards, diff --git a/fs/fs_context.c b/fs/fs_context.c index 851214d1d013..375023e40161 100644 --- a/fs/fs_context.c +++ b/fs/fs_context.c @@ -315,10 +315,31 @@ struct fs_context *fs_context_for_reconfigure(struct dentry *dentry, } EXPORT_SYMBOL(fs_context_for_reconfigure); +/** + * fs_context_for_submount: allocate a new fs_context for a submount + * @type: file_system_type of the new context + * @reference: reference dentry from which to copy relevant info + * + * Allocate a new fs_context suitable for a submount. This also ensures that + * the fc->security object is inherited from @reference (if needed). + */ struct fs_context *fs_context_for_submount(struct file_system_type *type, struct dentry *reference) { - return alloc_fs_context(type, reference, 0, 0, FS_CONTEXT_FOR_SUBMOUNT); + struct fs_context *fc; + int ret; + + fc = alloc_fs_context(type, reference, 0, 0, FS_CONTEXT_FOR_SUBMOUNT); + if (IS_ERR(fc)) + return fc; + + ret = security_fs_context_submount(fc, reference->d_sb); + if (ret) { + put_fs_context(fc); + return ERR_PTR(ret); + } + + return fc; } EXPORT_SYMBOL(fs_context_for_submount); diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index 7308a1a7599b..af796986baee 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -54,6 +54,7 @@ LSM_HOOK(int, 0, bprm_creds_from_file, struct linux_binprm *bprm, struct file *f LSM_HOOK(int, 0, bprm_check_security, struct linux_binprm *bprm) LSM_HOOK(void, LSM_RET_VOID, bprm_committing_creds, struct linux_binprm *bprm) LSM_HOOK(void, LSM_RET_VOID, bprm_committed_creds, struct linux_binprm *bprm) +LSM_HOOK(int, 0, fs_context_submount, struct fs_context *fc, struct super_block *reference) LSM_HOOK(int, 0, fs_context_dup, struct fs_context *fc, struct fs_context *src_sc) LSM_HOOK(int, -ENOPARAM, fs_context_parse_param, struct fs_context *fc, diff --git a/include/linux/security.h b/include/linux/security.h index 32828502f09e..bac98ea18f78 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -293,6 +293,7 @@ int security_bprm_creds_from_file(struct linux_binprm *bprm, struct file *file); int security_bprm_check(struct linux_binprm *bprm); void security_bprm_committing_creds(struct linux_binprm *bprm); void security_bprm_committed_creds(struct linux_binprm *bprm); +int security_fs_context_submount(struct fs_context *fc, struct super_block *reference); int security_fs_context_dup(struct fs_context *fc, struct fs_context *src_fc); int security_fs_context_parse_param(struct fs_context *fc, struct fs_parameter *param); int security_sb_alloc(struct super_block *sb); @@ -629,6 +630,11 @@ static inline void security_bprm_committed_creds(struct linux_binprm *bprm) { } +static inline int security_fs_context_submount(struct fs_context *fc, + struct super_block *reference) +{ + return 0; +} static inline int security_fs_context_dup(struct fs_context *fc, struct fs_context *src_fc) { diff --git a/security/security.c b/security/security.c index b720424ca37d..549104a447e3 100644 --- a/security/security.c +++ b/security/security.c @@ -1138,6 +1138,20 @@ void security_bprm_committed_creds(struct linux_binprm *bprm) call_void_hook(bprm_committed_creds, bprm); } +/** + * security_fs_context_submount() - Initialise fc->security + * @fc: new filesystem context + * @reference: dentry reference for submount/remount + * + * Fill out the ->security field for a new fs_context. + * + * Return: Returns 0 on success or negative error code on failure. + */ +int security_fs_context_submount(struct fs_context *fc, struct super_block *reference) +{ + return call_int_hook(fs_context_submount, 0, fc, reference); +} + /** * security_fs_context_dup() - Duplicate a fs_context LSM blob * @fc: destination filesystem context diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index d06e350fedee..afd663744041 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2745,6 +2745,27 @@ static int selinux_umount(struct vfsmount *mnt, int flags) FILESYSTEM__UNMOUNT, NULL); } +static int selinux_fs_context_submount(struct fs_context *fc, + struct super_block *reference) +{ + const struct superblock_security_struct *sbsec; + struct selinux_mnt_opts *opts; + + opts = kzalloc(sizeof(*opts), GFP_KERNEL); + if (!opts) + return -ENOMEM; + + sbsec = selinux_superblock(reference); + if (sbsec->flags & FSCONTEXT_MNT) + opts->fscontext_sid = sbsec->sid; + if (sbsec->flags & CONTEXT_MNT) + opts->context_sid = sbsec->mntpoint_sid; + if (sbsec->flags & DEFCONTEXT_MNT) + opts->defcontext_sid = sbsec->def_sid; + fc->security = opts; + return 0; +} + static int selinux_fs_context_dup(struct fs_context *fc, struct fs_context *src_fc) { @@ -7182,6 +7203,7 @@ static struct security_hook_list selinux_hooks[] __ro_after_init = { /* * PUT "CLONING" (ACCESSING + ALLOCATING) HOOKS HERE */ + LSM_HOOK_INIT(fs_context_submount, selinux_fs_context_submount), LSM_HOOK_INIT(fs_context_dup, selinux_fs_context_dup), LSM_HOOK_INIT(fs_context_parse_param, selinux_fs_context_parse_param), LSM_HOOK_INIT(sb_eat_lsm_opts, selinux_sb_eat_lsm_opts), diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 6e270cf3fd30..a8201cf22f20 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -614,6 +614,56 @@ static int smack_add_opt(int token, const char *s, void **mnt_opts) return -EINVAL; } +/** + * smack_fs_context_submount - Initialise security data for a filesystem context + * @fc: The filesystem context. + * @reference: reference superblock + * + * Returns 0 on success or -ENOMEM on error. + */ +static int smack_fs_context_submount(struct fs_context *fc, + struct super_block *reference) +{ + struct superblock_smack *sbsp; + struct smack_mnt_opts *ctx; + struct inode_smack *isp; + + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); + if (!ctx) + return -ENOMEM; + fc->security = ctx; + + sbsp = smack_superblock(reference); + isp = smack_inode(reference->s_root->d_inode); + + if (sbsp->smk_default) { + ctx->fsdefault = kstrdup(sbsp->smk_default->smk_known, GFP_KERNEL); + if (!ctx->fsdefault) + return -ENOMEM; + } + + if (sbsp->smk_floor) { + ctx->fsfloor = kstrdup(sbsp->smk_floor->smk_known, GFP_KERNEL); + if (!ctx->fsfloor) + return -ENOMEM; + } + + if (sbsp->smk_hat) { + ctx->fshat = kstrdup(sbsp->smk_hat->smk_known, GFP_KERNEL); + if (!ctx->fshat) + return -ENOMEM; + } + + if (isp->smk_flags & SMK_INODE_TRANSMUTE) { + if (sbsp->smk_root) { + ctx->fstransmute = kstrdup(sbsp->smk_root->smk_known, GFP_KERNEL); + if (!ctx->fstransmute) + return -ENOMEM; + } + } + return 0; +} + /** * smack_fs_context_dup - Duplicate the security data on fs_context duplication * @fc: The new filesystem context. @@ -4876,6 +4926,7 @@ static struct security_hook_list smack_hooks[] __ro_after_init = { LSM_HOOK_INIT(ptrace_traceme, smack_ptrace_traceme), LSM_HOOK_INIT(syslog, smack_syslog), + LSM_HOOK_INIT(fs_context_submount, smack_fs_context_submount), LSM_HOOK_INIT(fs_context_dup, smack_fs_context_dup), LSM_HOOK_INIT(fs_context_parse_param, smack_fs_context_parse_param),