From patchwork Tue Apr 27 11:37:29 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roberto Sassu X-Patchwork-Id: 12226565 X-Patchwork-Delegate: paul@paul-moore.com Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 90FFFC43611 for ; Tue, 27 Apr 2021 11:37:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5E6A6613C5 for ; Tue, 27 Apr 2021 11:37:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236098AbhD0Lih (ORCPT ); Tue, 27 Apr 2021 07:38:37 -0400 Received: from frasgout.his.huawei.com ([185.176.79.56]:2925 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235443AbhD0Lie (ORCPT ); Tue, 27 Apr 2021 07:38:34 -0400 Received: from fraeml714-chm.china.huawei.com (unknown [172.18.147.226]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4FTzxw2D2Bz77b74; Tue, 27 Apr 2021 19:27:16 +0800 (CST) Received: from roberto-ThinkStation-P620.huawei.com (10.204.62.217) by fraeml714-chm.china.huawei.com (10.206.15.33) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Tue, 27 Apr 2021 13:37:47 +0200 From: Roberto Sassu To: , , , CC: , , , , , , Roberto Sassu Subject: [PATCH v3 3/6] security: Pass xattrs allocated by LSMs to the inode_init_security hook Date: Tue, 27 Apr 2021 13:37:29 +0200 Message-ID: <20210427113732.471066-4-roberto.sassu@huawei.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210427113732.471066-1-roberto.sassu@huawei.com> References: <20210427113732.471066-1-roberto.sassu@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.204.62.217] X-ClientProxiedBy: lhreml751-chm.china.huawei.com (10.201.108.201) To fraeml714-chm.china.huawei.com (10.206.15.33) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: selinux@vger.kernel.org In preparation for moving EVM to the LSM infrastructure, this patch replaces the name, value, len triple with the xattr array pointer provided by security_inode_init_security(), and the base slot in the xattr array where LSMs can write xattrs. This patch also introduces the new helper lsm_find_xattr_slot(), to help LSMs find available slots in the xattr array (with a subsequent patch it will be possible to reserve more than one slot). The helper takes three arguments: the xattr array, the pointer of the base slot, whose value is incremented each time the helper is called, and the end slot so that the helper does not return a slot outside the array. Finally, this patch modifies also SELinux and Smack to use the new helper. Signed-off-by: Roberto Sassu --- include/linux/lsm_hook_defs.h | 4 ++-- include/linux/lsm_hooks.h | 21 ++++++++++++++++++--- security/security.c | 15 ++++++--------- security/selinux/hooks.c | 15 ++++++++------- security/smack/smack_lsm.c | 24 +++++++++++++----------- 5 files changed, 47 insertions(+), 32 deletions(-) diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index 477a597db013..20f91e93f511 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -111,8 +111,8 @@ LSM_HOOK(int, 0, path_notify, const struct path *path, u64 mask, LSM_HOOK(int, 0, inode_alloc_security, struct inode *inode) LSM_HOOK(void, LSM_RET_VOID, inode_free_security, struct inode *inode) LSM_HOOK(int, 0, inode_init_security, struct inode *inode, - struct inode *dir, const struct qstr *qstr, const char **name, - void **value, size_t *len) + struct inode *dir, const struct qstr *qstr, struct xattr *xattrs, + int *base_slot, void *fs_data) LSM_HOOK(int, 0, inode_init_security_anon, struct inode *inode, const struct qstr *name, const struct inode *context_inode) LSM_HOOK(int, 0, inode_create, struct inode *dir, struct dentry *dentry, diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index c5498f5174ce..197d6662b262 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -27,6 +27,7 @@ #include #include +#include #include /** @@ -227,9 +228,13 @@ * @inode contains the inode structure of the newly created inode. * @dir contains the inode structure of the parent directory. * @qstr contains the last path component of the new object - * @name will be set to the allocated name suffix (e.g. selinux). - * @value will be set to the allocated attribute value. - * @len will be set to the length of the value. + * @xattrs contains the full array of xattrs allocated by LSMs where + * ->name will be set to the allocated name suffix (e.g. selinux). + * ->value will be set to the allocated attribute value. + * ->len will be set to the length of the value. + * @base_slot contains the position in @xattrs from where xattrs + * can be written. + * @fs_data contains filesystem-specific data. * Returns 0 if @name and @value have been successfully set, * -EOPNOTSUPP if no security attribute is needed, or * -ENOMEM on memory allocation failure. @@ -1660,5 +1665,15 @@ static inline void security_delete_hooks(struct security_hook_list *hooks, #endif /* CONFIG_SECURITY_WRITABLE_HOOKS */ extern int lsm_inode_alloc(struct inode *inode); +static inline struct xattr *lsm_find_xattr_slot(struct xattr *xattrs, + int *base_slot, int end_slot) +{ + if (!xattrs) + return xattrs; + + if (*base_slot >= end_slot) + return NULL; + return xattrs + (*base_slot)++; +} #endif /* ! __LINUX_LSM_HOOKS_H */ diff --git a/security/security.c b/security/security.c index 692a148ce764..527a18fd6742 100644 --- a/security/security.c +++ b/security/security.c @@ -1043,26 +1043,23 @@ int security_inode_init_security(struct inode *inode, struct inode *dir, const initxattrs initxattrs, void *fs_data) { struct xattr new_xattrs[MAX_LSM_EVM_XATTR + 1]; - struct xattr *lsm_xattr, *evm_xattr, *xattr; - int ret; + struct xattr *xattr; + int ret, base_slot = 0; if (unlikely(IS_PRIVATE(inode))) return 0; if (!initxattrs) return call_int_hook(inode_init_security, -EOPNOTSUPP, inode, - dir, qstr, NULL, NULL, NULL); + dir, qstr, NULL, &base_slot, fs_data); memset(new_xattrs, 0, sizeof(new_xattrs)); - lsm_xattr = new_xattrs; ret = call_int_hook(inode_init_security, -EOPNOTSUPP, inode, dir, qstr, - &lsm_xattr->name, - &lsm_xattr->value, - &lsm_xattr->value_len); + new_xattrs, &base_slot, fs_data); if (ret) goto out; - evm_xattr = lsm_xattr + 1; - ret = evm_inode_init_security(inode, lsm_xattr, evm_xattr); + ret = evm_inode_init_security(inode, new_xattrs, + new_xattrs + base_slot); if (ret) goto out; ret = initxattrs(inode, new_xattrs, fs_data); diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index ddd097790d47..6319417129af 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2916,11 +2916,13 @@ static int selinux_dentry_create_files_as(struct dentry *dentry, int mode, static int selinux_inode_init_security(struct inode *inode, struct inode *dir, const struct qstr *qstr, - const char **name, - void **value, size_t *len) + struct xattr *xattrs, int *base_slot, + void *fs_data) { const struct task_security_struct *tsec = selinux_cred(current_cred()); struct superblock_security_struct *sbsec; + struct xattr *xattr = lsm_find_xattr_slot(xattrs, base_slot, + *base_slot + 1); u32 newsid, clen; int rc; char *context; @@ -2947,16 +2949,15 @@ static int selinux_inode_init_security(struct inode *inode, struct inode *dir, !(sbsec->flags & SBLABEL_MNT)) return -EOPNOTSUPP; - if (name) - *name = XATTR_SELINUX_SUFFIX; + if (xattr) { + xattr->name = XATTR_SELINUX_SUFFIX; - if (value && len) { rc = security_sid_to_context_force(&selinux_state, newsid, &context, &clen); if (rc) return rc; - *value = context; - *len = clen; + xattr->value = context; + xattr->value_len = clen; } return 0; diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 12a45e61c1a5..53e32cde09fb 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -962,26 +962,28 @@ static int smack_inode_alloc_security(struct inode *inode) * @inode: the newly created inode * @dir: containing directory object * @qstr: unused - * @name: where to put the attribute name - * @value: where to put the attribute value - * @len: where to put the length of the attribute + * @xattrs: where to put the attribute + * @base_slot: where to start to write in @xattrs + * @fs_data: unused * * Returns 0 if it all works out, -ENOMEM if there's no memory */ static int smack_inode_init_security(struct inode *inode, struct inode *dir, - const struct qstr *qstr, const char **name, - void **value, size_t *len) + const struct qstr *qstr, + struct xattr *xattrs, int *base_slot, + void *fs_data) { struct inode_smack *issp = smack_inode(inode); struct smack_known *skp = smk_of_current(); struct smack_known *isp = smk_of_inode(inode); struct smack_known *dsp = smk_of_inode(dir); + struct xattr *xattr = lsm_find_xattr_slot(xattrs, base_slot, + *base_slot + 1); int may; - if (name) - *name = XATTR_SMACK_SUFFIX; + if (xattr) { + xattr->name = XATTR_SMACK_SUFFIX; - if (value && len) { rcu_read_lock(); may = smk_access_entry(skp->smk_known, dsp->smk_known, &skp->smk_rules); @@ -999,11 +1001,11 @@ static int smack_inode_init_security(struct inode *inode, struct inode *dir, issp->smk_flags |= SMK_INODE_CHANGED; } - *value = kstrdup(isp->smk_known, GFP_NOFS); - if (*value == NULL) + xattr->value = kstrdup(isp->smk_known, GFP_NOFS); + if (xattr->value == NULL) return -ENOMEM; - *len = strlen(isp->smk_known); + xattr->value_len = strlen(isp->smk_known); } return 0;