diff mbox series

[15/28] security: Introduce inode_post_removexattr hook

Message ID 20230303181842.1087717-16-roberto.sassu@huaweicloud.com (mailing list archive)
State New, archived
Headers show
Series security: Move IMA and EVM to the LSM infrastructure | expand

Commit Message

Roberto Sassu March 3, 2023, 6:18 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_removexattr hook.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
 fs/xattr.c                    |  1 +
 include/linux/lsm_hook_defs.h |  2 ++
 include/linux/security.h      |  5 +++++
 security/security.c           | 14 ++++++++++++++
 4 files changed, 22 insertions(+)

Comments

Stefan Berger March 6, 2023, 7:17 p.m. UTC | #1
On 3/3/23 13:18, 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_removexattr hook.
> 
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>

Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Mimi Zohar March 8, 2023, 3:43 p.m. UTC | #2
Hi Roberto,

On Fri, 2023-03-03 at 19:18 +0100, 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_removexattr hook.
> 
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> ---
>  fs/xattr.c                    |  1 +
>  include/linux/lsm_hook_defs.h |  2 ++
>  include/linux/security.h      |  5 +++++
>  security/security.c           | 14 ++++++++++++++
>  4 files changed, 22 insertions(+)
> 
> diff --git a/fs/xattr.c b/fs/xattr.c
> index 14a7eb3c8fa..10c959d9fc6 100644
> --- a/fs/xattr.c
> +++ b/fs/xattr.c
> @@ -534,6 +534,7 @@ __vfs_removexattr_locked(struct mnt_idmap *idmap,
>  
>  	if (!error) {
>  		fsnotify_xattr(dentry);
> +		security_inode_post_removexattr(dentry, name);
>  		evm_inode_post_removexattr(dentry, name);
>  	}

Nothing wrong with this, but other places in this function test "if
(error) goto ...".   Perhaps it is time to clean this up.

>  
> diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
> index eedefbcdde3..2ae5224d967 100644
> --- a/include/linux/lsm_hook_defs.h
> +++ b/include/linux/lsm_hook_defs.h
> @@ -147,6 +147,8 @@ LSM_HOOK(int, 0, inode_getxattr, struct dentry *dentry, const char *name)
>  LSM_HOOK(int, 0, inode_listxattr, struct dentry *dentry)
>  LSM_HOOK(int, 0, inode_removexattr, struct mnt_idmap *idmap,
>  	 struct dentry *dentry, const char *name)
> +LSM_HOOK(void, LSM_RET_VOID, inode_post_removexattr, struct dentry *dentry,
> +	 const char *name)

@Christian should the security_inode_removexattr() and
security_inode_post_removexattr() arguments be the same?

>  LSM_HOOK(int, 0, inode_set_acl, struct mnt_idmap *idmap,
>  	 struct dentry *dentry, const char *acl_name, struct posix_acl *kacl)
>  LSM_HOOK(int, 0, inode_get_acl, struct mnt_idmap *idmap,
Roberto Sassu March 9, 2023, 1:07 p.m. UTC | #3
On Wed, 2023-03-08 at 10:43 -0500, Mimi Zohar wrote:
> Hi Roberto,
> 
> On Fri, 2023-03-03 at 19:18 +0100, 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_removexattr hook.
> > 
> > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> > ---
> >  fs/xattr.c                    |  1 +
> >  include/linux/lsm_hook_defs.h |  2 ++
> >  include/linux/security.h      |  5 +++++
> >  security/security.c           | 14 ++++++++++++++
> >  4 files changed, 22 insertions(+)
> > 
> > diff --git a/fs/xattr.c b/fs/xattr.c
> > index 14a7eb3c8fa..10c959d9fc6 100644
> > --- a/fs/xattr.c
> > +++ b/fs/xattr.c
> > @@ -534,6 +534,7 @@ __vfs_removexattr_locked(struct mnt_idmap *idmap,
> >  
> >  	if (!error) {
> >  		fsnotify_xattr(dentry);
> > +		security_inode_post_removexattr(dentry, name);
> >  		evm_inode_post_removexattr(dentry, name);
> >  	}
> 
> Nothing wrong with this, but other places in this function test "if
> (error) goto ...".   Perhaps it is time to clean this up.

Theoretically, all 'goto out' can be replaced with 'return error'.

I would be more in favor of minimizing the changes as much as possible
to reach the main goal. But it is ok also to change the last part.

Thanks

Roberto

> >  
> > diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
> > index eedefbcdde3..2ae5224d967 100644
> > --- a/include/linux/lsm_hook_defs.h
> > +++ b/include/linux/lsm_hook_defs.h
> > @@ -147,6 +147,8 @@ LSM_HOOK(int, 0, inode_getxattr, struct dentry *dentry, const char *name)
> >  LSM_HOOK(int, 0, inode_listxattr, struct dentry *dentry)
> >  LSM_HOOK(int, 0, inode_removexattr, struct mnt_idmap *idmap,
> >  	 struct dentry *dentry, const char *name)
> > +LSM_HOOK(void, LSM_RET_VOID, inode_post_removexattr, struct dentry *dentry,
> > +	 const char *name)
> 
> @Christian should the security_inode_removexattr() and
> security_inode_post_removexattr() arguments be the same?
> 
> >  LSM_HOOK(int, 0, inode_set_acl, struct mnt_idmap *idmap,
> >  	 struct dentry *dentry, const char *acl_name, struct posix_acl *kacl)
> >  LSM_HOOK(int, 0, inode_get_acl, struct mnt_idmap *idmap,
Roberto Sassu Aug. 30, 2023, 9:31 a.m. UTC | #4
On Wed, 2023-03-08 at 10:43 -0500, Mimi Zohar wrote:
> Hi Roberto,
> 
> On Fri, 2023-03-03 at 19:18 +0100, 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_removexattr hook.
> > 
> > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> > ---
> >  fs/xattr.c                    |  1 +
> >  include/linux/lsm_hook_defs.h |  2 ++
> >  include/linux/security.h      |  5 +++++
> >  security/security.c           | 14 ++++++++++++++
> >  4 files changed, 22 insertions(+)
> > 
> > diff --git a/fs/xattr.c b/fs/xattr.c
> > index 14a7eb3c8fa..10c959d9fc6 100644
> > --- a/fs/xattr.c
> > +++ b/fs/xattr.c
> > @@ -534,6 +534,7 @@ __vfs_removexattr_locked(struct mnt_idmap *idmap,
> >  
> >  	if (!error) {
> >  		fsnotify_xattr(dentry);
> > +		security_inode_post_removexattr(dentry, name);
> >  		evm_inode_post_removexattr(dentry, name);
> >  	}
> 
> Nothing wrong with this, but other places in this function test "if
> (error) goto ...".   Perhaps it is time to clean this up.
> 
> >  
> > diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
> > index eedefbcdde3..2ae5224d967 100644
> > --- a/include/linux/lsm_hook_defs.h
> > +++ b/include/linux/lsm_hook_defs.h
> > @@ -147,6 +147,8 @@ LSM_HOOK(int, 0, inode_getxattr, struct dentry *dentry, const char *name)
> >  LSM_HOOK(int, 0, inode_listxattr, struct dentry *dentry)
> >  LSM_HOOK(int, 0, inode_removexattr, struct mnt_idmap *idmap,
> >  	 struct dentry *dentry, const char *name)
> > +LSM_HOOK(void, LSM_RET_VOID, inode_post_removexattr, struct dentry *dentry,
> > +	 const char *name)
> 
> @Christian should the security_inode_removexattr() and
> security_inode_post_removexattr() arguments be the same?

Probably this got lost.

Christian, should security_inode_post_removexattr() have the idmap
parameter as well?

Thanks

Roberto

> >  LSM_HOOK(int, 0, inode_set_acl, struct mnt_idmap *idmap,
> >  	 struct dentry *dentry, const char *acl_name, struct posix_acl *kacl)
> >  LSM_HOOK(int, 0, inode_get_acl, struct mnt_idmap *idmap,
>
Christian Brauner Aug. 30, 2023, 9:53 a.m. UTC | #5
On Wed, Aug 30, 2023 at 11:31:35AM +0200, Roberto Sassu wrote:
> On Wed, 2023-03-08 at 10:43 -0500, Mimi Zohar wrote:
> > Hi Roberto,
> > 
> > On Fri, 2023-03-03 at 19:18 +0100, 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_removexattr hook.
> > > 
> > > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> > > ---
> > >  fs/xattr.c                    |  1 +
> > >  include/linux/lsm_hook_defs.h |  2 ++
> > >  include/linux/security.h      |  5 +++++
> > >  security/security.c           | 14 ++++++++++++++
> > >  4 files changed, 22 insertions(+)
> > > 
> > > diff --git a/fs/xattr.c b/fs/xattr.c
> > > index 14a7eb3c8fa..10c959d9fc6 100644
> > > --- a/fs/xattr.c
> > > +++ b/fs/xattr.c
> > > @@ -534,6 +534,7 @@ __vfs_removexattr_locked(struct mnt_idmap *idmap,
> > >  
> > >  	if (!error) {
> > >  		fsnotify_xattr(dentry);
> > > +		security_inode_post_removexattr(dentry, name);
> > >  		evm_inode_post_removexattr(dentry, name);
> > >  	}
> > 
> > Nothing wrong with this, but other places in this function test "if
> > (error) goto ...".   Perhaps it is time to clean this up.
> > 
> > >  
> > > diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
> > > index eedefbcdde3..2ae5224d967 100644
> > > --- a/include/linux/lsm_hook_defs.h
> > > +++ b/include/linux/lsm_hook_defs.h
> > > @@ -147,6 +147,8 @@ LSM_HOOK(int, 0, inode_getxattr, struct dentry *dentry, const char *name)
> > >  LSM_HOOK(int, 0, inode_listxattr, struct dentry *dentry)
> > >  LSM_HOOK(int, 0, inode_removexattr, struct mnt_idmap *idmap,
> > >  	 struct dentry *dentry, const char *name)
> > > +LSM_HOOK(void, LSM_RET_VOID, inode_post_removexattr, struct dentry *dentry,
> > > +	 const char *name)
> > 
> > @Christian should the security_inode_removexattr() and
> > security_inode_post_removexattr() arguments be the same?
> 
> Probably this got lost.
> 
> Christian, should security_inode_post_removexattr() have the idmap
> parameter as well?

Only if you call anything from any implementers of the hook that needs
access to the idmap.
diff mbox series

Patch

diff --git a/fs/xattr.c b/fs/xattr.c
index 14a7eb3c8fa..10c959d9fc6 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -534,6 +534,7 @@  __vfs_removexattr_locked(struct mnt_idmap *idmap,
 
 	if (!error) {
 		fsnotify_xattr(dentry);
+		security_inode_post_removexattr(dentry, name);
 		evm_inode_post_removexattr(dentry, name);
 	}
 
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index eedefbcdde3..2ae5224d967 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -147,6 +147,8 @@  LSM_HOOK(int, 0, inode_getxattr, struct dentry *dentry, const char *name)
 LSM_HOOK(int, 0, inode_listxattr, struct dentry *dentry)
 LSM_HOOK(int, 0, inode_removexattr, struct mnt_idmap *idmap,
 	 struct dentry *dentry, const char *name)
+LSM_HOOK(void, LSM_RET_VOID, inode_post_removexattr, struct dentry *dentry,
+	 const char *name)
 LSM_HOOK(int, 0, inode_set_acl, struct mnt_idmap *idmap,
 	 struct dentry *dentry, const char *acl_name, struct posix_acl *kacl)
 LSM_HOOK(int, 0, inode_get_acl, struct mnt_idmap *idmap,
diff --git a/include/linux/security.h b/include/linux/security.h
index 64224216f6c..b511f608958 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -373,6 +373,7 @@  int security_inode_getxattr(struct dentry *dentry, const char *name);
 int security_inode_listxattr(struct dentry *dentry);
 int security_inode_removexattr(struct mnt_idmap *idmap,
 			       struct dentry *dentry, const char *name);
+void security_inode_post_removexattr(struct dentry *dentry, const char *name);
 int security_inode_need_killpriv(struct dentry *dentry);
 int security_inode_killpriv(struct mnt_idmap *idmap, struct dentry *dentry);
 int security_inode_getsecurity(struct mnt_idmap *idmap,
@@ -918,6 +919,10 @@  static inline int security_inode_removexattr(struct mnt_idmap *idmap,
 	return cap_inode_removexattr(idmap, dentry, name);
 }
 
+static inline void security_inode_post_removexattr(struct dentry *dentry,
+						   const char *name)
+{ }
+
 static inline int security_inode_need_killpriv(struct dentry *dentry)
 {
 	return cap_inode_need_killpriv(dentry);
diff --git a/security/security.c b/security/security.c
index 2dbf225f5d8..6bf4a92db94 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2404,6 +2404,20 @@  int security_inode_removexattr(struct mnt_idmap *idmap,
 	return evm_inode_removexattr(idmap, dentry, name);
 }
 
+/**
+ * security_inode_post_removexattr() - Update the inode after a removexattr op
+ * @dentry: file
+ * @name: xattr name
+ *
+ * Update the inode after a successful removexattr operation.
+ */
+void security_inode_post_removexattr(struct dentry *dentry, const char *name)
+{
+	if (unlikely(IS_PRIVATE(d_backing_inode(dentry))))
+		return;
+	call_void_hook(inode_post_removexattr, dentry, name);
+}
+
 /**
  * security_inode_need_killpriv() - Check if security_inode_killpriv() required
  * @dentry: associated dentry