diff mbox series

[v2,11/25] security: add hooks for set/get/remove of fscaps

Message ID 20240221-idmap-fscap-refactor-v2-11-3039364623bd@kernel.org
State New
Headers
Series fs: use type-safe uid representation for filesystem capabilities |

Commit Message

Seth Forshee (DigitalOcean) Feb. 21, 2024, 9:24 p.m. UTC 
  In preparation for moving fscaps out of the xattr code paths, add new
security hooks. These hooks are largely needed because common kernel
code will pass around struct vfs_caps pointers, which EVM will need to
convert to raw xattr data for verification and updates of its hashes.

Signed-off-by: Seth Forshee (DigitalOcean) <sforshee@kernel.org>
---
 include/linux/lsm_hook_defs.h |  7 +++++
 include/linux/security.h      | 33 +++++++++++++++++++++
 security/security.c           | 69 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 109 insertions(+)

Comments

Paul Moore Feb. 21, 2024, 11:31 p.m. UTC | #1 
On Wed, Feb 21, 2024 at 4:26 PM Seth Forshee (DigitalOcean)
<sforshee@kernel.org> wrote:
>
> In preparation for moving fscaps out of the xattr code paths, add new
> security hooks. These hooks are largely needed because common kernel
> code will pass around struct vfs_caps pointers, which EVM will need to
> convert to raw xattr data for verification and updates of its hashes.
>
> Signed-off-by: Seth Forshee (DigitalOcean) <sforshee@kernel.org>
> ---
>  include/linux/lsm_hook_defs.h |  7 +++++
>  include/linux/security.h      | 33 +++++++++++++++++++++
>  security/security.c           | 69 +++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 109 insertions(+)

One minor problem below, but assuming you fix that, this looks okay to me.

Acked-by: Paul Moore <paul@paul-moore.com>

> diff --git a/security/security.c b/security/security.c
> index 3aaad75c9ce8..0d210da9862c 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -2351,6 +2351,75 @@ int security_inode_remove_acl(struct mnt_idmap *idmap,

..

> +/**
> + * security_inode_get_fscaps() - Check if reading fscaps is allowed
> + * @dentry: file

You are missing an entry for the @idmap parameter.

> + * Check permission before getting fscaps.
> + *
> + * Return: Returns 0 if permission is granted.
> + */
> +int security_inode_get_fscaps(struct mnt_idmap *idmap, struct dentry *dentry)
> +{
> +       if (unlikely(IS_PRIVATE(d_backing_inode(dentry))))
> +               return 0;
> +       return call_int_hook(inode_get_fscaps, 0, idmap, dentry);
> +}
Seth Forshee (DigitalOcean) Feb. 22, 2024, 12:07 a.m. UTC | #2 
On Wed, Feb 21, 2024 at 06:31:42PM -0500, Paul Moore wrote:
> On Wed, Feb 21, 2024 at 4:26 PM Seth Forshee (DigitalOcean)
> <sforshee@kernel.org> wrote:
> >
> > In preparation for moving fscaps out of the xattr code paths, add new
> > security hooks. These hooks are largely needed because common kernel
> > code will pass around struct vfs_caps pointers, which EVM will need to
> > convert to raw xattr data for verification and updates of its hashes.
> >
> > Signed-off-by: Seth Forshee (DigitalOcean) <sforshee@kernel.org>
> > ---
> >  include/linux/lsm_hook_defs.h |  7 +++++
> >  include/linux/security.h      | 33 +++++++++++++++++++++
> >  security/security.c           | 69 +++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 109 insertions(+)
> 
> One minor problem below, but assuming you fix that, this looks okay to me.
> 
> Acked-by: Paul Moore <paul@paul-moore.com>
> 
> > diff --git a/security/security.c b/security/security.c
> > index 3aaad75c9ce8..0d210da9862c 100644
> > --- a/security/security.c
> > +++ b/security/security.c
> > @@ -2351,6 +2351,75 @@ int security_inode_remove_acl(struct mnt_idmap *idmap,
> 
> ...
> 
> > +/**
> > + * security_inode_get_fscaps() - Check if reading fscaps is allowed
> > + * @dentry: file
> 
> You are missing an entry for the @idmap parameter.

Fixed, thanks!
Christian Brauner Feb. 23, 2024, 8:23 a.m. UTC | #3 
On Wed, Feb 21, 2024 at 03:24:42PM -0600, Seth Forshee (DigitalOcean) wrote:
> In preparation for moving fscaps out of the xattr code paths, add new
> security hooks. These hooks are largely needed because common kernel
> code will pass around struct vfs_caps pointers, which EVM will need to
> convert to raw xattr data for verification and updates of its hashes.
> 
> Signed-off-by: Seth Forshee (DigitalOcean) <sforshee@kernel.org>
> ---

Looks good,
Reviewed-by: Christian Brauner <brauner@kernel.org>
Roberto Sassu March 1, 2024, 3:59 p.m. UTC | #4 
On Wed, 2024-02-21 at 15:24 -0600, Seth Forshee (DigitalOcean) wrote:
> In preparation for moving fscaps out of the xattr code paths, add new
> security hooks. These hooks are largely needed because common kernel
> code will pass around struct vfs_caps pointers, which EVM will need to
> convert to raw xattr data for verification and updates of its hashes.
> 
> Signed-off-by: Seth Forshee (DigitalOcean) <sforshee@kernel.org>
> ---
>  include/linux/lsm_hook_defs.h |  7 +++++
>  include/linux/security.h      | 33 +++++++++++++++++++++
>  security/security.c           | 69 +++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 109 insertions(+)
> 
> diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
> index 76458b6d53da..7b3c23f9e4a5 100644
> --- a/include/linux/lsm_hook_defs.h
> +++ b/include/linux/lsm_hook_defs.h
> @@ -152,6 +152,13 @@ LSM_HOOK(int, 0, inode_get_acl, struct mnt_idmap *idmap,
>  	 struct dentry *dentry, const char *acl_name)
>  LSM_HOOK(int, 0, inode_remove_acl, struct mnt_idmap *idmap,
>  	 struct dentry *dentry, const char *acl_name)
> +LSM_HOOK(int, 0, inode_set_fscaps, struct mnt_idmap *idmap,
> +	 struct dentry *dentry, const struct vfs_caps *caps, int flags);
> +LSM_HOOK(void, LSM_RET_VOID, inode_post_set_fscaps, struct mnt_idmap *idmap,
> +	 struct dentry *dentry, const struct vfs_caps *caps, int flags);
> +LSM_HOOK(int, 0, inode_get_fscaps, struct mnt_idmap *idmap, struct dentry *dentry);
> +LSM_HOOK(int, 0, inode_remove_fscaps, struct mnt_idmap *idmap,
> +	 struct dentry *dentry);

Uhm, there should not be semicolons here.

Roberto

>  LSM_HOOK(int, 0, inode_need_killpriv, struct dentry *dentry)
>  LSM_HOOK(int, 0, inode_killpriv, struct mnt_idmap *idmap,
>  	 struct dentry *dentry)
> diff --git a/include/linux/security.h b/include/linux/security.h
> index d0eb20f90b26..40be548e5e12 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -378,6 +378,13 @@ 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);
> +int security_inode_set_fscaps(struct mnt_idmap *idmap, struct dentry *dentry,
> +			      const struct vfs_caps *caps, int flags);
> +void security_inode_post_set_fscaps(struct mnt_idmap *idmap,
> +				    struct dentry *dentry,
> +				    const struct vfs_caps *caps, int flags);
> +int security_inode_get_fscaps(struct mnt_idmap *idmap, struct dentry *dentry);
> +int security_inode_remove_fscaps(struct mnt_idmap *idmap, struct dentry *dentry);
>  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,
> @@ -935,6 +942,32 @@ static inline int security_inode_removexattr(struct mnt_idmap *idmap,
>  	return cap_inode_removexattr(idmap, dentry, name);
>  }
>  
> +static inline int security_inode_set_fscaps(struct mnt_idmap *idmap,
> +					    struct dentry *dentry,
> +					    const struct vfs_caps *caps,
> +					    int flags)
> +{
> +	return 0;
> +}
> +static void security_inode_post_set_fscaps(struct mnt_idmap *idmap,
> +					   struct dentry *dentry,
> +					   const struct vfs_caps *caps,
> +					   int flags)
> +{
> +}
> +
> +static int security_inode_get_fscaps(struct mnt_idmap *idmap,
> +				     struct dentry *dentry)
> +{
> +	return 0;
> +}
> +
> +static int security_inode_remove_fscaps(struct mnt_idmap *idmap,
> +					struct dentry *dentry)
> +{
> +	return 0;
> +}
> +
>  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 3aaad75c9ce8..0d210da9862c 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -2351,6 +2351,75 @@ int security_inode_remove_acl(struct mnt_idmap *idmap,
>  	return evm_inode_remove_acl(idmap, dentry, acl_name);
>  }
>  
> +/**
> + * security_inode_set_fscaps() - Check if setting fscaps is allowed
> + * @idmap: idmap of the mount
> + * @dentry: file
> + * @caps: fscaps to be written
> + * @flags: flags for setxattr
> + *
> + * Check permission before setting the file capabilities given in @vfs_caps.
> + *
> + * Return: Returns 0 if permission is granted.
> + */
> +int security_inode_set_fscaps(struct mnt_idmap *idmap, struct dentry *dentry,
> +			      const struct vfs_caps *caps, int flags)
> +{
> +	if (unlikely(IS_PRIVATE(d_backing_inode(dentry))))
> +		return 0;
> +	return call_int_hook(inode_set_fscaps, 0, idmap, dentry, caps, flags);
> +}
> +
> +/**
> + * security_inode_post_set_fscaps() - Update the inode after setting fscaps
> + * @idmap: idmap of the mount
> + * @dentry: file
> + * @caps: fscaps to be written
> + * @flags: flags for setxattr
> + *
> + * Update inode security field after successfully setting fscaps.
> + *
> + */
> +void security_inode_post_set_fscaps(struct mnt_idmap *idmap,
> +				    struct dentry *dentry,
> +				    const struct vfs_caps *caps, int flags)
> +{
> +	if (unlikely(IS_PRIVATE(d_backing_inode(dentry))))
> +		return;
> +	call_void_hook(inode_post_set_fscaps, idmap, dentry, caps, flags);
> +}
> +
> +/**
> + * security_inode_get_fscaps() - Check if reading fscaps is allowed
> + * @dentry: file
> + *
> + * Check permission before getting fscaps.
> + *
> + * Return: Returns 0 if permission is granted.
> + */
> +int security_inode_get_fscaps(struct mnt_idmap *idmap, struct dentry *dentry)
> +{
> +	if (unlikely(IS_PRIVATE(d_backing_inode(dentry))))
> +		return 0;
> +	return call_int_hook(inode_get_fscaps, 0, idmap, dentry);
> +}
> +
> +/**
> + * security_inode_remove_fscaps() - Check if removing fscaps is allowed
> + * @idmap: idmap of the mount
> + * @dentry: file
> + *
> + * Check permission before removing fscaps.
> + *
> + * Return: Returns 0 if permission is granted.
> + */
> +int security_inode_remove_fscaps(struct mnt_idmap *idmap, struct dentry *dentry)
> +{
> +	if (unlikely(IS_PRIVATE(d_backing_inode(dentry))))
> +		return 0;
> +	return call_int_hook(inode_remove_fscaps, 0, idmap, dentry);
> +}
> +
>  /**
>   * security_inode_post_setxattr() - Update the inode after a setxattr operation
>   * @dentry: file
>
Seth Forshee (DigitalOcean) March 1, 2024, 6:50 p.m. UTC | #5 
On Fri, Mar 01, 2024 at 04:59:16PM +0100, Roberto Sassu wrote:
> On Wed, 2024-02-21 at 15:24 -0600, Seth Forshee (DigitalOcean) wrote:
> > In preparation for moving fscaps out of the xattr code paths, add new
> > security hooks. These hooks are largely needed because common kernel
> > code will pass around struct vfs_caps pointers, which EVM will need to
> > convert to raw xattr data for verification and updates of its hashes.
> > 
> > Signed-off-by: Seth Forshee (DigitalOcean) <sforshee@kernel.org>
> > ---
> >  include/linux/lsm_hook_defs.h |  7 +++++
> >  include/linux/security.h      | 33 +++++++++++++++++++++
> >  security/security.c           | 69 +++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 109 insertions(+)
> > 
> > diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
> > index 76458b6d53da..7b3c23f9e4a5 100644
> > --- a/include/linux/lsm_hook_defs.h
> > +++ b/include/linux/lsm_hook_defs.h
> > @@ -152,6 +152,13 @@ LSM_HOOK(int, 0, inode_get_acl, struct mnt_idmap *idmap,
> >  	 struct dentry *dentry, const char *acl_name)
> >  LSM_HOOK(int, 0, inode_remove_acl, struct mnt_idmap *idmap,
> >  	 struct dentry *dentry, const char *acl_name)
> > +LSM_HOOK(int, 0, inode_set_fscaps, struct mnt_idmap *idmap,
> > +	 struct dentry *dentry, const struct vfs_caps *caps, int flags);
> > +LSM_HOOK(void, LSM_RET_VOID, inode_post_set_fscaps, struct mnt_idmap *idmap,
> > +	 struct dentry *dentry, const struct vfs_caps *caps, int flags);
> > +LSM_HOOK(int, 0, inode_get_fscaps, struct mnt_idmap *idmap, struct dentry *dentry);
> > +LSM_HOOK(int, 0, inode_remove_fscaps, struct mnt_idmap *idmap,
> > +	 struct dentry *dentry);
> 
> Uhm, there should not be semicolons here.

Yes, I've fixed this already for the next version.

Thanks,
Seth
diff mbox series

Patch

diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 76458b6d53da..7b3c23f9e4a5 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -152,6 +152,13 @@  LSM_HOOK(int, 0, inode_get_acl, struct mnt_idmap *idmap,
 	 struct dentry *dentry, const char *acl_name)
 LSM_HOOK(int, 0, inode_remove_acl, struct mnt_idmap *idmap,
 	 struct dentry *dentry, const char *acl_name)
+LSM_HOOK(int, 0, inode_set_fscaps, struct mnt_idmap *idmap,
+	 struct dentry *dentry, const struct vfs_caps *caps, int flags);
+LSM_HOOK(void, LSM_RET_VOID, inode_post_set_fscaps, struct mnt_idmap *idmap,
+	 struct dentry *dentry, const struct vfs_caps *caps, int flags);
+LSM_HOOK(int, 0, inode_get_fscaps, struct mnt_idmap *idmap, struct dentry *dentry);
+LSM_HOOK(int, 0, inode_remove_fscaps, struct mnt_idmap *idmap,
+	 struct dentry *dentry);
 LSM_HOOK(int, 0, inode_need_killpriv, struct dentry *dentry)
 LSM_HOOK(int, 0, inode_killpriv, struct mnt_idmap *idmap,
 	 struct dentry *dentry)
diff --git a/include/linux/security.h b/include/linux/security.h
index d0eb20f90b26..40be548e5e12 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -378,6 +378,13 @@  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);
+int security_inode_set_fscaps(struct mnt_idmap *idmap, struct dentry *dentry,
+			      const struct vfs_caps *caps, int flags);
+void security_inode_post_set_fscaps(struct mnt_idmap *idmap,
+				    struct dentry *dentry,
+				    const struct vfs_caps *caps, int flags);
+int security_inode_get_fscaps(struct mnt_idmap *idmap, struct dentry *dentry);
+int security_inode_remove_fscaps(struct mnt_idmap *idmap, struct dentry *dentry);
 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,
@@ -935,6 +942,32 @@  static inline int security_inode_removexattr(struct mnt_idmap *idmap,
 	return cap_inode_removexattr(idmap, dentry, name);
 }
 
+static inline int security_inode_set_fscaps(struct mnt_idmap *idmap,
+					    struct dentry *dentry,
+					    const struct vfs_caps *caps,
+					    int flags)
+{
+	return 0;
+}
+static void security_inode_post_set_fscaps(struct mnt_idmap *idmap,
+					   struct dentry *dentry,
+					   const struct vfs_caps *caps,
+					   int flags)
+{
+}
+
+static int security_inode_get_fscaps(struct mnt_idmap *idmap,
+				     struct dentry *dentry)
+{
+	return 0;
+}
+
+static int security_inode_remove_fscaps(struct mnt_idmap *idmap,
+					struct dentry *dentry)
+{
+	return 0;
+}
+
 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 3aaad75c9ce8..0d210da9862c 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2351,6 +2351,75 @@  int security_inode_remove_acl(struct mnt_idmap *idmap,
 	return evm_inode_remove_acl(idmap, dentry, acl_name);
 }
 
+/**
+ * security_inode_set_fscaps() - Check if setting fscaps is allowed
+ * @idmap: idmap of the mount
+ * @dentry: file
+ * @caps: fscaps to be written
+ * @flags: flags for setxattr
+ *
+ * Check permission before setting the file capabilities given in @vfs_caps.
+ *
+ * Return: Returns 0 if permission is granted.
+ */
+int security_inode_set_fscaps(struct mnt_idmap *idmap, struct dentry *dentry,
+			      const struct vfs_caps *caps, int flags)
+{
+	if (unlikely(IS_PRIVATE(d_backing_inode(dentry))))
+		return 0;
+	return call_int_hook(inode_set_fscaps, 0, idmap, dentry, caps, flags);
+}
+
+/**
+ * security_inode_post_set_fscaps() - Update the inode after setting fscaps
+ * @idmap: idmap of the mount
+ * @dentry: file
+ * @caps: fscaps to be written
+ * @flags: flags for setxattr
+ *
+ * Update inode security field after successfully setting fscaps.
+ *
+ */
+void security_inode_post_set_fscaps(struct mnt_idmap *idmap,
+				    struct dentry *dentry,
+				    const struct vfs_caps *caps, int flags)
+{
+	if (unlikely(IS_PRIVATE(d_backing_inode(dentry))))
+		return;
+	call_void_hook(inode_post_set_fscaps, idmap, dentry, caps, flags);
+}
+
+/**
+ * security_inode_get_fscaps() - Check if reading fscaps is allowed
+ * @dentry: file
+ *
+ * Check permission before getting fscaps.
+ *
+ * Return: Returns 0 if permission is granted.
+ */
+int security_inode_get_fscaps(struct mnt_idmap *idmap, struct dentry *dentry)
+{
+	if (unlikely(IS_PRIVATE(d_backing_inode(dentry))))
+		return 0;
+	return call_int_hook(inode_get_fscaps, 0, idmap, dentry);
+}
+
+/**
+ * security_inode_remove_fscaps() - Check if removing fscaps is allowed
+ * @idmap: idmap of the mount
+ * @dentry: file
+ *
+ * Check permission before removing fscaps.
+ *
+ * Return: Returns 0 if permission is granted.
+ */
+int security_inode_remove_fscaps(struct mnt_idmap *idmap, struct dentry *dentry)
+{
+	if (unlikely(IS_PRIVATE(d_backing_inode(dentry))))
+		return 0;
+	return call_int_hook(inode_remove_fscaps, 0, idmap, dentry);
+}
+
 /**
  * security_inode_post_setxattr() - Update the inode after a setxattr operation
  * @dentry: file