diff mbox series

[v5,15/23] security: Introduce inode_post_create_tmpfile hook

Message ID 20231107134012.682009-16-roberto.sassu@huaweicloud.com
State New
Headers
Series security: Move IMA and EVM to the LSM infrastructure |

Commit Message

Roberto Sassu Nov. 7, 2023, 1:40 p.m. UTC 
  From: Roberto Sassu <roberto.sassu@huawei.com>

In preparation for moving IMA and EVM to the LSM infrastructure, introduce
the inode_post_create_tmpfile hook.

As temp files can be made persistent, treat new temp files like other new
files, so that the file hash is calculated and stored in the security
xattr.

LSMs could also take some action after temp files have been created.

The new hook cannot return an error and cannot cause the operation to be
canceled.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
 fs/namei.c                    |  1 +
 include/linux/lsm_hook_defs.h |  2 ++
 include/linux/security.h      |  6 ++++++
 security/security.c           | 15 +++++++++++++++
 4 files changed, 24 insertions(+)

Comments

Casey Schaufler Nov. 7, 2023, 5:42 p.m. UTC | #1 
On 11/7/2023 5:40 AM, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu@huawei.com>
>
> In preparation for moving IMA and EVM to the LSM infrastructure, introduce
> the inode_post_create_tmpfile hook.
>
> As temp files can be made persistent, treat new temp files like other new
> files, so that the file hash is calculated and stored in the security
> xattr.
>
> LSMs could also take some action after temp files have been created.
>
> The new hook cannot return an error and cannot cause the operation to be
> canceled.
>
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>

Acked-by: Casey Schaufler <casey@schaufler-ca.com>


> ---
>  fs/namei.c                    |  1 +
>  include/linux/lsm_hook_defs.h |  2 ++
>  include/linux/security.h      |  6 ++++++
>  security/security.c           | 15 +++++++++++++++
>  4 files changed, 24 insertions(+)
>
> diff --git a/fs/namei.c b/fs/namei.c
> index b7f433720b1e..adb3ab27951a 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -3686,6 +3686,7 @@ static int vfs_tmpfile(struct mnt_idmap *idmap,
>  		inode->i_state |= I_LINKABLE;
>  		spin_unlock(&inode->i_lock);
>  	}
> +	security_inode_post_create_tmpfile(idmap, inode);
>  	ima_post_create_tmpfile(idmap, inode);
>  	return 0;
>  }
> diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
> index e491951399f7..ec5319ec2e85 100644
> --- a/include/linux/lsm_hook_defs.h
> +++ b/include/linux/lsm_hook_defs.h
> @@ -121,6 +121,8 @@ 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,
>  	 umode_t mode)
> +LSM_HOOK(void, LSM_RET_VOID, inode_post_create_tmpfile, struct mnt_idmap *idmap,
> +	 struct inode *inode)
>  LSM_HOOK(int, 0, inode_link, struct dentry *old_dentry, struct inode *dir,
>  	 struct dentry *new_dentry)
>  LSM_HOOK(int, 0, inode_unlink, struct inode *dir, struct dentry *dentry)
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 68cbdc84506e..0c85f0337a9e 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -344,6 +344,8 @@ int security_inode_init_security_anon(struct inode *inode,
>  				      const struct qstr *name,
>  				      const struct inode *context_inode);
>  int security_inode_create(struct inode *dir, struct dentry *dentry, umode_t mode);
> +void security_inode_post_create_tmpfile(struct mnt_idmap *idmap,
> +					struct inode *inode);
>  int security_inode_link(struct dentry *old_dentry, struct inode *dir,
>  			 struct dentry *new_dentry);
>  int security_inode_unlink(struct inode *dir, struct dentry *dentry);
> @@ -809,6 +811,10 @@ static inline int security_inode_create(struct inode *dir,
>  	return 0;
>  }
>  
> +static inline void
> +security_inode_post_create_tmpfile(struct mnt_idmap *idmap, struct inode *inode)
> +{ }
> +
>  static inline int security_inode_link(struct dentry *old_dentry,
>  				       struct inode *dir,
>  				       struct dentry *new_dentry)
> diff --git a/security/security.c b/security/security.c
> index 5eaf5f2aa5ea..ca650c285fd9 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -2013,6 +2013,21 @@ int security_inode_create(struct inode *dir, struct dentry *dentry,
>  }
>  EXPORT_SYMBOL_GPL(security_inode_create);
>  
> +/**
> + * security_inode_post_create_tmpfile() - Update inode security of new tmpfile
> + * @idmap: idmap of the mount
> + * @inode: inode of the new tmpfile
> + *
> + * Update inode security data after a tmpfile has been created.
> + */
> +void security_inode_post_create_tmpfile(struct mnt_idmap *idmap,
> +					struct inode *inode)
> +{
> +	if (unlikely(IS_PRIVATE(inode)))
> +		return;
> +	call_void_hook(inode_post_create_tmpfile, idmap, inode);
> +}
> +
>  /**
>   * security_inode_link() - Check if creating a hard link is allowed
>   * @old_dentry: existing file
Paul Moore Nov. 16, 2023, 4:33 a.m. UTC | #2 
On Nov  7, 2023 Roberto Sassu <roberto.sassu@huaweicloud.com> wrote:
> 
> In preparation for moving IMA and EVM to the LSM infrastructure, introduce
> the inode_post_create_tmpfile hook.
> 
> As temp files can be made persistent, treat new temp files like other new
> files, so that the file hash is calculated and stored in the security
> xattr.
> 
> LSMs could also take some action after temp files have been created.
> 
> The new hook cannot return an error and cannot cause the operation to be
> canceled.
> 
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> Acked-by: Casey Schaufler <casey@schaufler-ca.com>
> Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
> ---
>  fs/namei.c                    |  1 +
>  include/linux/lsm_hook_defs.h |  2 ++
>  include/linux/security.h      |  6 ++++++
>  security/security.c           | 15 +++++++++++++++
>  4 files changed, 24 insertions(+)

...

> diff --git a/security/security.c b/security/security.c
> index 5eaf5f2aa5ea..ca650c285fd9 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -2013,6 +2013,21 @@ int security_inode_create(struct inode *dir, struct dentry *dentry,
>  }
>  EXPORT_SYMBOL_GPL(security_inode_create);
>  
> +/**
> + * security_inode_post_create_tmpfile() - Update inode security of new tmpfile
> + * @idmap: idmap of the mount
> + * @inode: inode of the new tmpfile
> + *
> + * Update inode security data after a tmpfile has been created.
> + */
> +void security_inode_post_create_tmpfile(struct mnt_idmap *idmap,
> +					struct inode *inode)
> +{
> +	if (unlikely(IS_PRIVATE(inode)))
> +		return;

See my previous comments/questions about checking for S_PRIVATE here.

> +	call_void_hook(inode_post_create_tmpfile, idmap, inode);
> +}
> +
>  /**
>   * security_inode_link() - Check if creating a hard link is allowed
>   * @old_dentry: existing file
> -- 
> 2.34.1

--
paul-moore.com
diff mbox series

Patch

diff --git a/fs/namei.c b/fs/namei.c
index b7f433720b1e..adb3ab27951a 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3686,6 +3686,7 @@  static int vfs_tmpfile(struct mnt_idmap *idmap,
 		inode->i_state |= I_LINKABLE;
 		spin_unlock(&inode->i_lock);
 	}
+	security_inode_post_create_tmpfile(idmap, inode);
 	ima_post_create_tmpfile(idmap, inode);
 	return 0;
 }
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index e491951399f7..ec5319ec2e85 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -121,6 +121,8 @@  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,
 	 umode_t mode)
+LSM_HOOK(void, LSM_RET_VOID, inode_post_create_tmpfile, struct mnt_idmap *idmap,
+	 struct inode *inode)
 LSM_HOOK(int, 0, inode_link, struct dentry *old_dentry, struct inode *dir,
 	 struct dentry *new_dentry)
 LSM_HOOK(int, 0, inode_unlink, struct inode *dir, struct dentry *dentry)
diff --git a/include/linux/security.h b/include/linux/security.h
index 68cbdc84506e..0c85f0337a9e 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -344,6 +344,8 @@  int security_inode_init_security_anon(struct inode *inode,
 				      const struct qstr *name,
 				      const struct inode *context_inode);
 int security_inode_create(struct inode *dir, struct dentry *dentry, umode_t mode);
+void security_inode_post_create_tmpfile(struct mnt_idmap *idmap,
+					struct inode *inode);
 int security_inode_link(struct dentry *old_dentry, struct inode *dir,
 			 struct dentry *new_dentry);
 int security_inode_unlink(struct inode *dir, struct dentry *dentry);
@@ -809,6 +811,10 @@  static inline int security_inode_create(struct inode *dir,
 	return 0;
 }
 
+static inline void
+security_inode_post_create_tmpfile(struct mnt_idmap *idmap, struct inode *inode)
+{ }
+
 static inline int security_inode_link(struct dentry *old_dentry,
 				       struct inode *dir,
 				       struct dentry *new_dentry)
diff --git a/security/security.c b/security/security.c
index 5eaf5f2aa5ea..ca650c285fd9 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2013,6 +2013,21 @@  int security_inode_create(struct inode *dir, struct dentry *dentry,
 }
 EXPORT_SYMBOL_GPL(security_inode_create);
 
+/**
+ * security_inode_post_create_tmpfile() - Update inode security of new tmpfile
+ * @idmap: idmap of the mount
+ * @inode: inode of the new tmpfile
+ *
+ * Update inode security data after a tmpfile has been created.
+ */
+void security_inode_post_create_tmpfile(struct mnt_idmap *idmap,
+					struct inode *inode)
+{
+	if (unlikely(IS_PRIVATE(inode)))
+		return;
+	call_void_hook(inode_post_create_tmpfile, idmap, inode);
+}
+
 /**
  * security_inode_link() - Check if creating a hard link is allowed
  * @old_dentry: existing file