From: Casey Schaufler <casey@schaufler-ca.com> To: Mimi Zohar <zohar@linux.ibm.com>, Roberto Sassu <roberto.sassu@huaweicloud.com>, mark@fasheh.com, jlbec@evilplan.org, joseph.qi@linux.alibaba.com, dmitry.kasatkin@gmail.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, stephen.smalley.work@gmail.com, eparis@parisplace.org Cc: ocfs2-devel@oss.oracle.com, reiserfs-devel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, linux-kernel@vger.kernel.org, keescook@chromium.org, nicolas.bouchinet@clip-os.org, Roberto Sassu <roberto.sassu@huawei.com>, casey@schaufler-ca.com Subject: Re: [PATCH v6 4/6] security: Allow all LSMs to provide xattrs for inode_init_security hook Date: Tue, 29 Nov 2022 07:39:42 -0800 [thread overview] Message-ID: <50232f2b-d5ce-1e5a-3f5b-8d3eb53fe1ec@schaufler-ca.com> (raw) In-Reply-To: <9859294adb0a9b9587ea7fb70a836a312aaf3c69.camel@linux.ibm.com> On 11/29/2022 3:23 AM, Mimi Zohar wrote: > On Thu, 2022-11-24 at 09:17 +0100, Roberto Sassu wrote: >> On Wed, 2022-11-23 at 20:14 -0500, Mimi Zohar wrote: >>> Hi Roberto, >>> >>> On Wed, 2022-11-23 at 16:47 +0100, Roberto Sassu wrote: >>>> int security_inode_init_security(struct inode *inode, struct inode *dir, >>>> const struct qstr *qstr, >>>> 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 security_hook_list *P; >>>> + struct xattr *new_xattrs; >>>> + struct xattr *xattr; >>>> + int ret = -EOPNOTSUPP, num_filled_xattrs = 0; >>>> >>>> if (unlikely(IS_PRIVATE(inode))) >>>> return 0; >>>> >>>> + if (!blob_sizes.lbs_xattr) >>>> + return 0; >>>> + >>>> if (!initxattrs) >>>> return call_int_hook(inode_init_security, -EOPNOTSUPP, inode, >>>> - dir, qstr, NULL, NULL, NULL); >>>> - 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); >>>> - if (ret) >>>> + dir, qstr, NULL); >>>> + /* Allocate +1 for EVM and +1 as terminator. */ >>>> + new_xattrs = kcalloc(blob_sizes.lbs_xattr + 2, sizeof(*new_xattrs), >>>> + GFP_NOFS); >>>> + if (!new_xattrs) >>>> + return -ENOMEM; >>>> + >>>> + hlist_for_each_entry(P, &security_hook_heads.inode_init_security, >>>> + list) { >>>> + ret = P->hook.inode_init_security(inode, dir, qstr, new_xattrs); >>>> + if (ret && ret != -EOPNOTSUPP) >>>> + goto out; >>>> + if (ret == -EOPNOTSUPP) >>>> + continue; >>> In this context, -EOPNOTSUPP originally signified that the filesystem >>> does not support writing xattrs. Writing any xattr would fail. >>> Returning -ENODATA for no LSM xattr(s) data would seem to be more >>> appropriate than -EOPNOTSUPP. >> Hi Mimi >> >> I thought about adding new return values. Currently only -EOPNOTSUPP >> and -ENOMEM are expected as errors. >> >> However, changing the conventions would mean revisiting the LSMs code >> and ensuring that they follow the new conventions. >> >> I would be more in favor of not touching it. > Casey, Paul, any comment? I don't see value in adding -ENODATA as a value special to the infrastructure. What would the infrastructure do differently? The use of -EOPNOTSUPP isn't consistent throughout, and the amount of "correctness" you get by returning -ENODATA is really small. > >>>> + /* >>>> + * As the number of xattrs reserved by LSMs is not directly >>>> + * available, directly use the total number blob_sizes.lbs_xattr >>>> + * to keep the code simple, while being not the most efficient >>>> + * way. >>>> + */ >>>> + ret = security_check_compact_filled_xattrs(new_xattrs, >>>> + blob_sizes.lbs_xattr, >>>> + &num_filled_xattrs); >>>> + if (ret < 0) { >>>> + ret = -ENOMEM; >>>> + goto out; >>>> + } >>>> + } >>>> + >>>> + if (!num_filled_xattrs) >>>> 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 + num_filled_xattrs); >>>> if (ret) >>>> goto out; >>>> ret = initxattrs(inode, new_xattrs, fs_data); >>>> out: >>>> for (xattr = new_xattrs; xattr->value != NULL; xattr++) >>>> kfree(xattr->value); >>>> + kfree(new_xattrs); >>>> return (ret == -EOPNOTSUPP) ? 0 : ret; >>>> } >>> b >
WARNING: multiple messages have this Message-ID (diff)
From: Casey Schaufler via Ocfs2-devel <ocfs2-devel@oss.oracle.com> To: Mimi Zohar <zohar@linux.ibm.com>, Roberto Sassu <roberto.sassu@huaweicloud.com>, mark@fasheh.com, jlbec@evilplan.org, joseph.qi@linux.alibaba.com, dmitry.kasatkin@gmail.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, stephen.smalley.work@gmail.com, eparis@parisplace.org Cc: nicolas.bouchinet@clip-os.org, keescook@chromium.org, selinux@vger.kernel.org, Roberto Sassu <roberto.sassu@huawei.com>, reiserfs-devel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, casey@schaufler-ca.com, linux-integrity@vger.kernel.org, ocfs2-devel@oss.oracle.com Subject: Re: [Ocfs2-devel] [PATCH v6 4/6] security: Allow all LSMs to provide xattrs for inode_init_security hook Date: Tue, 29 Nov 2022 07:39:42 -0800 [thread overview] Message-ID: <50232f2b-d5ce-1e5a-3f5b-8d3eb53fe1ec@schaufler-ca.com> (raw) In-Reply-To: <9859294adb0a9b9587ea7fb70a836a312aaf3c69.camel@linux.ibm.com> On 11/29/2022 3:23 AM, Mimi Zohar wrote: > On Thu, 2022-11-24 at 09:17 +0100, Roberto Sassu wrote: >> On Wed, 2022-11-23 at 20:14 -0500, Mimi Zohar wrote: >>> Hi Roberto, >>> >>> On Wed, 2022-11-23 at 16:47 +0100, Roberto Sassu wrote: >>>> int security_inode_init_security(struct inode *inode, struct inode *dir, >>>> const struct qstr *qstr, >>>> 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 security_hook_list *P; >>>> + struct xattr *new_xattrs; >>>> + struct xattr *xattr; >>>> + int ret = -EOPNOTSUPP, num_filled_xattrs = 0; >>>> >>>> if (unlikely(IS_PRIVATE(inode))) >>>> return 0; >>>> >>>> + if (!blob_sizes.lbs_xattr) >>>> + return 0; >>>> + >>>> if (!initxattrs) >>>> return call_int_hook(inode_init_security, -EOPNOTSUPP, inode, >>>> - dir, qstr, NULL, NULL, NULL); >>>> - 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); >>>> - if (ret) >>>> + dir, qstr, NULL); >>>> + /* Allocate +1 for EVM and +1 as terminator. */ >>>> + new_xattrs = kcalloc(blob_sizes.lbs_xattr + 2, sizeof(*new_xattrs), >>>> + GFP_NOFS); >>>> + if (!new_xattrs) >>>> + return -ENOMEM; >>>> + >>>> + hlist_for_each_entry(P, &security_hook_heads.inode_init_security, >>>> + list) { >>>> + ret = P->hook.inode_init_security(inode, dir, qstr, new_xattrs); >>>> + if (ret && ret != -EOPNOTSUPP) >>>> + goto out; >>>> + if (ret == -EOPNOTSUPP) >>>> + continue; >>> In this context, -EOPNOTSUPP originally signified that the filesystem >>> does not support writing xattrs. Writing any xattr would fail. >>> Returning -ENODATA for no LSM xattr(s) data would seem to be more >>> appropriate than -EOPNOTSUPP. >> Hi Mimi >> >> I thought about adding new return values. Currently only -EOPNOTSUPP >> and -ENOMEM are expected as errors. >> >> However, changing the conventions would mean revisiting the LSMs code >> and ensuring that they follow the new conventions. >> >> I would be more in favor of not touching it. > Casey, Paul, any comment? I don't see value in adding -ENODATA as a value special to the infrastructure. What would the infrastructure do differently? The use of -EOPNOTSUPP isn't consistent throughout, and the amount of "correctness" you get by returning -ENODATA is really small. > >>>> + /* >>>> + * As the number of xattrs reserved by LSMs is not directly >>>> + * available, directly use the total number blob_sizes.lbs_xattr >>>> + * to keep the code simple, while being not the most efficient >>>> + * way. >>>> + */ >>>> + ret = security_check_compact_filled_xattrs(new_xattrs, >>>> + blob_sizes.lbs_xattr, >>>> + &num_filled_xattrs); >>>> + if (ret < 0) { >>>> + ret = -ENOMEM; >>>> + goto out; >>>> + } >>>> + } >>>> + >>>> + if (!num_filled_xattrs) >>>> 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 + num_filled_xattrs); >>>> if (ret) >>>> goto out; >>>> ret = initxattrs(inode, new_xattrs, fs_data); >>>> out: >>>> for (xattr = new_xattrs; xattr->value != NULL; xattr++) >>>> kfree(xattr->value); >>>> + kfree(new_xattrs); >>>> return (ret == -EOPNOTSUPP) ? 0 : ret; >>>> } >>> b > _______________________________________________ Ocfs2-devel mailing list Ocfs2-devel@oss.oracle.com https://oss.oracle.com/mailman/listinfo/ocfs2-devel
next prev parent reply other threads:[~2022-11-29 15:40 UTC|newest] Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-11-23 15:47 [PATCH v6 0/6] evm: Do HMAC of multiple per LSM xattrs for new inodes Roberto Sassu 2022-11-23 15:47 ` [Ocfs2-devel] " Roberto Sassu via Ocfs2-devel 2022-11-23 15:47 ` [PATCH v6 1/6] reiserfs: Switch to security_inode_init_security() Roberto Sassu 2022-11-23 15:47 ` [Ocfs2-devel] " Roberto Sassu via Ocfs2-devel 2022-11-23 15:47 ` [PATCH v6 2/6] ocfs2: " Roberto Sassu 2022-11-23 15:47 ` [Ocfs2-devel] " Roberto Sassu via Ocfs2-devel 2022-11-23 15:47 ` [PATCH v6 3/6] security: Remove security_old_inode_init_security() Roberto Sassu 2022-11-23 15:47 ` [Ocfs2-devel] " Roberto Sassu via Ocfs2-devel 2022-11-23 15:47 ` [Ocfs2-devel] [PATCH v6 4/6] security: Allow all LSMs to provide xattrs for inode_init_security hook Roberto Sassu via Ocfs2-devel 2022-11-23 15:47 ` Roberto Sassu 2022-11-23 17:17 ` Casey Schaufler 2022-11-23 17:17 ` [Ocfs2-devel] " Casey Schaufler via Ocfs2-devel 2022-11-24 7:55 ` Roberto Sassu 2022-11-24 7:55 ` [Ocfs2-devel] " Roberto Sassu via Ocfs2-devel 2022-11-24 1:14 ` Mimi Zohar 2022-11-24 1:14 ` [Ocfs2-devel] " Mimi Zohar via Ocfs2-devel 2022-11-24 8:17 ` Roberto Sassu 2022-11-24 8:17 ` [Ocfs2-devel] " Roberto Sassu via Ocfs2-devel 2022-11-29 11:23 ` Mimi Zohar 2022-11-29 11:23 ` [Ocfs2-devel] " Mimi Zohar via Ocfs2-devel 2022-11-29 15:39 ` Casey Schaufler [this message] 2022-11-29 15:39 ` Casey Schaufler via Ocfs2-devel 2022-11-30 21:23 ` Mimi Zohar 2022-11-30 21:23 ` [Ocfs2-devel] " Mimi Zohar via Ocfs2-devel 2022-11-23 15:47 ` [Ocfs2-devel] [PATCH v6 5/6] evm: Align evm_inode_init_security() definition with LSM infrastructure Roberto Sassu via Ocfs2-devel 2022-11-23 15:47 ` Roberto Sassu 2022-11-23 15:47 ` [PATCH v6 6/6] evm: Support multiple LSMs providing an xattr Roberto Sassu 2022-11-23 15:47 ` [Ocfs2-devel] " Roberto Sassu via Ocfs2-devel 2022-11-23 16:22 ` [PATCH v6 0/6] evm: Do HMAC of multiple per LSM xattrs for new inodes Mimi Zohar 2022-11-23 16:22 ` [Ocfs2-devel] " Mimi Zohar via Ocfs2-devel 2022-11-23 17:20 ` Casey Schaufler 2022-11-23 17:20 ` [Ocfs2-devel] " Casey Schaufler via Ocfs2-devel
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