From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roberto Sassu Subject: Re: [PATCH v10 3/4] evm: Align evm_inode_init_security() definition with LSM infrastructure Date: Tue, 11 Apr 2023 09:58:59 +0200 Message-ID: <0d73e16cb3697ed7ba227bc530883dfafa74b1aa.camel@huaweicloud.com> References: <20230331123221.3273328-1-roberto.sassu@huaweicloud.com> <20230331123221.3273328-4-roberto.sassu@huaweicloud.com> <404a022216d33063ff8f8b4f0d31d9d38a2da4d4.camel@linux.ibm.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <404a022216d33063ff8f8b4f0d31d9d38a2da4d4.camel@linux.ibm.com> List-ID: Content-Type: text/plain; charset="us-ascii" To: Mimi Zohar , dmitry.kasatkin@gmail.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, stephen.smalley.work@gmail.com, eparis@parisplace.org, casey@schaufler-ca.com Cc: reiserfs-devel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, bpf@vger.kernel.org, kpsingh@kernel.org, keescook@chromium.org, nicolas.bouchinet@clip-os.org, Roberto Sassu On Tue, 2023-04-11 at 03:22 -0400, Mimi Zohar wrote: > On Fri, 2023-03-31 at 14:32 +0200, Roberto Sassu wrote: > > From: Roberto Sassu > > > > Change the evm_inode_init_security() definition to align with the LSM > > infrastructure. Keep the existing behavior of including in the HMAC > > calculation only the first xattr provided by LSMs. > > > > Changing the evm_inode_init_security() definition requires passing the > > xattr array allocated by security_inode_init_security(), and the number of > > xattrs filled by previously invoked LSMs. > > > > Use the newly introduced lsm_get_xattr_slot() to position EVM correctly in > > the xattrs array, like a regular LSM, and to increment the number of filled > > slots. For now, the LSM infrastructure allocates enough xattrs slots to > > store the EVM xattr, without using the reservation mechanism. > > > > Signed-off-by: Roberto Sassu > > --- > > include/linux/evm.h | 13 +++++++------ > > security/integrity/evm/evm_main.c | 16 ++++++++++------ > > security/security.c | 6 +++--- > > 3 files changed, 20 insertions(+), 15 deletions(-) > > > > diff --git a/include/linux/evm.h b/include/linux/evm.h > > index 7dc1ee74169..597632c71c7 100644 > > --- a/include/linux/evm.h > > +++ b/include/linux/evm.h > > @@ -56,9 +56,9 @@ static inline void evm_inode_post_set_acl(struct dentry *dentry, > > { > > return evm_inode_post_setxattr(dentry, acl_name, NULL, 0); > > } > > -extern int evm_inode_init_security(struct inode *inode, > > - const struct xattr *xattr_array, > > - struct xattr *evm); > > +extern int evm_inode_init_security(struct inode *inode, struct inode *dir, > > + const struct qstr *qstr, > > + struct xattr *xattrs, int *xattr_count); > > extern bool evm_revalidate_status(const char *xattr_name); > > extern int evm_protected_xattr_if_enabled(const char *req_xattr_name); > > extern int evm_read_protected_xattrs(struct dentry *dentry, u8 *buffer, > > @@ -157,9 +157,10 @@ static inline void evm_inode_post_set_acl(struct dentry *dentry, > > return; > > } > > > > -static inline int evm_inode_init_security(struct inode *inode, > > - const struct xattr *xattr_array, > > - struct xattr *evm) > > +static inline int evm_inode_init_security(struct inode *inode, struct inode *dir, > > + const struct qstr *qstr, > > + struct xattr *xattrs, > > + int *xattr_count) > > { > > return 0; > > } > > diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c > > index cf24c525558..475196ce712 100644 > > --- a/security/integrity/evm/evm_main.c > > +++ b/security/integrity/evm/evm_main.c > > @@ -21,6 +21,7 @@ > > #include > > #include > > #include > > +#include > > > > #include > > #include > > @@ -864,23 +865,26 @@ void evm_inode_post_setattr(struct dentry *dentry, int ia_valid) > > /* > > * evm_inode_init_security - initializes security.evm HMAC value > > */ > > -int evm_inode_init_security(struct inode *inode, > > - const struct xattr *lsm_xattr, > > - struct xattr *evm_xattr) > > +int evm_inode_init_security(struct inode *inode, struct inode *dir, > > + const struct qstr *qstr, struct xattr *xattrs, > > + int *xattr_count) > > { > > struct evm_xattr *xattr_data; > > + struct xattr *evm_xattr; > > int rc; > > > > - if (!(evm_initialized & EVM_INIT_HMAC) || > > - !evm_protected_xattr(lsm_xattr->name)) > > + if (!(evm_initialized & EVM_INIT_HMAC) || !xattrs || > > + !evm_protected_xattr(xattrs->name)) > > return 0; > > > > + evm_xattr = lsm_get_xattr_slot(xattrs, xattr_count); > > + > > xattr_data = kzalloc(sizeof(*xattr_data), GFP_NOFS); > > if (!xattr_data) > > return -ENOMEM; > > > > xattr_data->data.type = EVM_XATTR_HMAC; > > - rc = evm_init_hmac(inode, lsm_xattr, xattr_data->digest); > > + rc = evm_init_hmac(inode, xattrs, xattr_data->digest); > > if (rc < 0) > > goto out; > > > > diff --git a/security/security.c b/security/security.c > > index 1aeaa8ce449..ef7779ec8b2 100644 > > --- a/security/security.c > > +++ b/security/security.c > > @@ -1645,9 +1645,9 @@ int security_inode_init_security(struct inode *inode, struct inode *dir, > > if (!xattr_count) > > goto out; > > > > - ret = evm_inode_init_security(inode, new_xattrs, > > - new_xattrs + xattr_count); > > - if (ret) > > + ret = evm_inode_init_security(inode, dir, qstr, new_xattrs, > > + &xattr_count); > > + if (ret && ret != -EOPNOTSUPP) > > As previously discussed, -EOPNOTSUPP originally meant that the > filesystem itself did not support writing xattrs. So there was no > point in trying to write the EVM security xattr. With the change in > -EOPNOTSUPP meaning, it will now try to write the EVM security xattr. > Instead of glossing over the change in behavior, it needs to at least > be mentioned in the patch description. Oh, my mistake. I forgot to update this part (evm_inode_init_security() now returns zero instead of -EOPNOTSUPP). Thanks Roberto > > goto out; > > ret = initxattrs(inode, new_xattrs, fs_data); > > out: