[PATCH] security,fs,nfs,net: update security_inode_listsecurity() interface

[PATCH] security,fs,nfs,net: update security_inode_listsecurity() interface

[Stephen Smalley]

Update the security_inode_listsecurity() interface to allow
use of the xattr_list_one() helper and update the hook
implementations.

Link: https://lore.kernel.org/selinux/20250424152822.2719-1-stephen.smalley.work@gmail.com/

Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
---
This patch is relative to the one linked above, which in theory is on
vfs.fixes but doesn't appear to have been pushed when I looked.

 fs/nfs/nfs4proc.c             |  9 +++++----
 fs/xattr.c                    | 20 ++++++++------------
 include/linux/lsm_hook_defs.h |  4 ++--
 include/linux/security.h      |  5 +++--
 net/socket.c                  |  8 +-------
 security/security.c           | 16 ++++++++--------
 security/selinux/hooks.c      | 10 +++-------
 security/smack/smack_lsm.c    | 13 ++++---------
 8 files changed, 34 insertions(+), 51 deletions(-)

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 970f28dbf253..a1d7cb0acb5e 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -8023,12 +8023,13 @@ static int nfs4_xattr_get_nfs4_label(const struct xattr_handler *handler,
 static ssize_t
 nfs4_listxattr_nfs4_label(struct inode *inode, char *list, size_t list_len)
 {
-	int len = 0;
+	ssize_t len = 0;
+	int err;
 
 	if (nfs_server_capable(inode, NFS_CAP_SECURITY_LABEL)) {
-		len = security_inode_listsecurity(inode, list, list_len);
-		if (len >= 0 && list_len && len > list_len)
-			return -ERANGE;
+		err = security_inode_listsecurity(inode, &list, &len);
+		if (err)
+			len = err;
 	}
 	return len;
 }
diff --git a/fs/xattr.c b/fs/xattr.c
index 2fc314b27120..fdd2f387bfd5 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -492,9 +492,12 @@ vfs_listxattr(struct dentry *dentry, char *list, size_t size)
 	if (inode->i_op->listxattr) {
 		error = inode->i_op->listxattr(dentry, list, size);
 	} else {
-		error = security_inode_listsecurity(inode, list, size);
-		if (size && error > size)
-			error = -ERANGE;
+		char *buffer = list;
+		ssize_t len = 0;
+
+		error = security_inode_listsecurity(inode, &buffer, &len);
+		if (!error)
+			error = len;
 	}
 	return error;
 }
@@ -1469,17 +1472,10 @@ ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
 	if (err)
 		return err;
 
-	err = security_inode_listsecurity(inode, buffer, remaining_size);
-	if (err < 0)
+	err = security_inode_listsecurity(inode, &buffer, &remaining_size);
+	if (err)
 		return err;
 
-	if (buffer) {
-		if (remaining_size < err)
-			return -ERANGE;
-		buffer += err;
-	}
-	remaining_size -= err;
-
 	read_lock(&xattrs->lock);
 	for (rbp = rb_first(&xattrs->rb_root); rbp; rbp = rb_next(rbp)) {
 		xattr = rb_entry(rbp, struct simple_xattr, rb_node);
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index bf3bbac4e02a..3c3919dcdebc 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -174,8 +174,8 @@ LSM_HOOK(int, -EOPNOTSUPP, inode_getsecurity, struct mnt_idmap *idmap,
 	 struct inode *inode, const char *name, void **buffer, bool alloc)
 LSM_HOOK(int, -EOPNOTSUPP, inode_setsecurity, struct inode *inode,
 	 const char *name, const void *value, size_t size, int flags)
-LSM_HOOK(int, 0, inode_listsecurity, struct inode *inode, char *buffer,
-	 size_t buffer_size)
+LSM_HOOK(int, 0, inode_listsecurity, struct inode *inode, char **buffer,
+	 ssize_t *remaining_size)
 LSM_HOOK(void, LSM_RET_VOID, inode_getlsmprop, struct inode *inode,
 	 struct lsm_prop *prop)
 LSM_HOOK(int, 0, inode_copy_up, struct dentry *src, struct cred **new)
diff --git a/include/linux/security.h b/include/linux/security.h
index cc9b54d95d22..0efc6a0ab56d 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -457,7 +457,7 @@ int security_inode_getsecurity(struct mnt_idmap *idmap,
 			       struct inode *inode, const char *name,
 			       void **buffer, bool alloc);
 int security_inode_setsecurity(struct inode *inode, const char *name, const void *value, size_t size, int flags);
-int security_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer_size);
+int security_inode_listsecurity(struct inode *inode, char **buffer, ssize_t *remaining_size);
 void security_inode_getlsmprop(struct inode *inode, struct lsm_prop *prop);
 int security_inode_copy_up(struct dentry *src, struct cred **new);
 int security_inode_copy_up_xattr(struct dentry *src, const char *name);
@@ -1077,7 +1077,8 @@ static inline int security_inode_setsecurity(struct inode *inode, const char *na
 	return -EOPNOTSUPP;
 }
 
-static inline int security_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer_size)
+static inline int security_inode_listsecurity(struct inode *inode,
+					char **buffer, ssize_t *remaining_size)
 {
 	return 0;
 }
diff --git a/net/socket.c b/net/socket.c
index 9a0e720f0859..52e3670dc89b 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -562,15 +562,9 @@ static ssize_t sockfs_listxattr(struct dentry *dentry, char *buffer,
 	ssize_t len;
 	ssize_t used = 0;
 
-	len = security_inode_listsecurity(d_inode(dentry), buffer, size);
+	len = security_inode_listsecurity(d_inode(dentry), &buffer, &used);
 	if (len < 0)
 		return len;
-	used += len;
-	if (buffer) {
-		if (size < used)
-			return -ERANGE;
-		buffer += len;
-	}
 
 	len = (XATTR_NAME_SOCKPROTONAME_LEN + 1);
 	used += len;
diff --git a/security/security.c b/security/security.c
index fb57e8fddd91..3985d040d5a9 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2710,22 +2710,22 @@ int security_inode_setsecurity(struct inode *inode, const char *name,
 /**
  * security_inode_listsecurity() - List the xattr security label names
  * @inode: inode
- * @buffer: buffer
- * @buffer_size: size of buffer
+ * @buffer: pointer to buffer
+ * @remaining_size: pointer to remaining size of buffer
  *
  * Copy the extended attribute names for the security labels associated with
- * @inode into @buffer.  The maximum size of @buffer is specified by
- * @buffer_size.  @buffer may be NULL to request the size of the buffer
- * required.
+ * @inode into *(@buffer).  The remaining size of @buffer is specified by
+ * *(@remaining_size).  *(@buffer) may be NULL to request the size of the
+ * buffer required. Updates *(@buffer) and *(@remaining_size).
  *
- * Return: Returns number of bytes used/required on success.
+ * Return: Returns 0 on success, or -errno on failure.
  */
 int security_inode_listsecurity(struct inode *inode,
-				char *buffer, size_t buffer_size)
+				char **buffer, ssize_t *remaining_size)
 {
 	if (unlikely(IS_PRIVATE(inode)))
 		return 0;
-	return call_int_hook(inode_listsecurity, inode, buffer, buffer_size);
+	return call_int_hook(inode_listsecurity, inode, buffer, remaining_size);
 }
 EXPORT_SYMBOL(security_inode_listsecurity);
 
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index b8115df536ab..e6c98ebbf7bc 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3612,16 +3612,12 @@ static int selinux_inode_setsecurity(struct inode *inode, const char *name,
 	return 0;
 }
 
-static int selinux_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer_size)
+static int selinux_inode_listsecurity(struct inode *inode, char **buffer,
+				ssize_t *remaining_size)
 {
-	const int len = sizeof(XATTR_NAME_SELINUX);
-
 	if (!selinux_initialized())
 		return 0;
-
-	if (buffer && len <= buffer_size)
-		memcpy(buffer, XATTR_NAME_SELINUX, len);
-	return len;
+	return xattr_list_one(buffer, remaining_size, XATTR_NAME_SELINUX);
 }
 
 static void selinux_inode_getlsmprop(struct inode *inode, struct lsm_prop *prop)
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 99833168604e..3f7ac865532e 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -1619,17 +1619,12 @@ static int smack_inode_getsecurity(struct mnt_idmap *idmap,
  * smack_inode_listsecurity - list the Smack attributes
  * @inode: the object
  * @buffer: where they go
- * @buffer_size: size of buffer
+ * @remaining_size: size of buffer
  */
-static int smack_inode_listsecurity(struct inode *inode, char *buffer,
-				    size_t buffer_size)
+static int smack_inode_listsecurity(struct inode *inode, char **buffer,
+				    ssize_t *remaining_size)
 {
-	int len = sizeof(XATTR_NAME_SMACK);
-
-	if (buffer != NULL && len <= buffer_size)
-		memcpy(buffer, XATTR_NAME_SMACK, len);
-
-	return len;
+	return xattr_list_one(buffer, remaining_size, XATTR_NAME_SMACK);
 }
 
 /**
-- 
2.49.0

Re: [PATCH] security,fs,nfs,net: update security_inode_listsecurity() interface

[Stephen Smalley]

On Mon, Apr 28, 2025 at 12:00 PM Stephen Smalley
<stephen.smalley.work@gmail.com> wrote:
>
> Update the security_inode_listsecurity() interface to allow
> use of the xattr_list_one() helper and update the hook
> implementations.
>
> Link: https://lore.kernel.org/selinux/20250424152822.2719-1-stephen.smalley.work@gmail.com/
>
> Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
> ---
> This patch is relative to the one linked above, which in theory is on
> vfs.fixes but doesn't appear to have been pushed when I looked.
>
>  fs/nfs/nfs4proc.c             |  9 +++++----
>  fs/xattr.c                    | 20 ++++++++------------
>  include/linux/lsm_hook_defs.h |  4 ++--
>  include/linux/security.h      |  5 +++--
>  net/socket.c                  |  8 +-------
>  security/security.c           | 16 ++++++++--------
>  security/selinux/hooks.c      | 10 +++-------
>  security/smack/smack_lsm.c    | 13 ++++---------
>  8 files changed, 34 insertions(+), 51 deletions(-)
>
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index 970f28dbf253..a1d7cb0acb5e 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -8023,12 +8023,13 @@ static int nfs4_xattr_get_nfs4_label(const struct xattr_handler *handler,
>  static ssize_t
>  nfs4_listxattr_nfs4_label(struct inode *inode, char *list, size_t list_len)
>  {
> -       int len = 0;
> +       ssize_t len = 0;
> +       int err;
>
>         if (nfs_server_capable(inode, NFS_CAP_SECURITY_LABEL)) {
> -               len = security_inode_listsecurity(inode, list, list_len);
> -               if (len >= 0 && list_len && len > list_len)
> -                       return -ERANGE;
> +               err = security_inode_listsecurity(inode, &list, &len);
> +               if (err)
> +                       len = err;

That's obviously wrong, sorry for the noise. v2 coming.

>         }
>         return len;
>  }
> diff --git a/fs/xattr.c b/fs/xattr.c
> index 2fc314b27120..fdd2f387bfd5 100644
> --- a/fs/xattr.c
> +++ b/fs/xattr.c
> @@ -492,9 +492,12 @@ vfs_listxattr(struct dentry *dentry, char *list, size_t size)
>         if (inode->i_op->listxattr) {
>                 error = inode->i_op->listxattr(dentry, list, size);
>         } else {
> -               error = security_inode_listsecurity(inode, list, size);
> -               if (size && error > size)
> -                       error = -ERANGE;
> +               char *buffer = list;
> +               ssize_t len = 0;
> +
> +               error = security_inode_listsecurity(inode, &buffer, &len);

Also wrong.

> +               if (!error)
> +                       error = len;
>         }
>         return error;
>  }
> @@ -1469,17 +1472,10 @@ ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
>         if (err)
>                 return err;
>
> -       err = security_inode_listsecurity(inode, buffer, remaining_size);
> -       if (err < 0)
> +       err = security_inode_listsecurity(inode, &buffer, &remaining_size);
> +       if (err)
>                 return err;
>
> -       if (buffer) {
> -               if (remaining_size < err)
> -                       return -ERANGE;
> -               buffer += err;
> -       }
> -       remaining_size -= err;
> -
>         read_lock(&xattrs->lock);
>         for (rbp = rb_first(&xattrs->rb_root); rbp; rbp = rb_next(rbp)) {
>                 xattr = rb_entry(rbp, struct simple_xattr, rb_node);
> diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
> index bf3bbac4e02a..3c3919dcdebc 100644
> --- a/include/linux/lsm_hook_defs.h
> +++ b/include/linux/lsm_hook_defs.h
> @@ -174,8 +174,8 @@ LSM_HOOK(int, -EOPNOTSUPP, inode_getsecurity, struct mnt_idmap *idmap,
>          struct inode *inode, const char *name, void **buffer, bool alloc)
>  LSM_HOOK(int, -EOPNOTSUPP, inode_setsecurity, struct inode *inode,
>          const char *name, const void *value, size_t size, int flags)
> -LSM_HOOK(int, 0, inode_listsecurity, struct inode *inode, char *buffer,
> -        size_t buffer_size)
> +LSM_HOOK(int, 0, inode_listsecurity, struct inode *inode, char **buffer,
> +        ssize_t *remaining_size)
>  LSM_HOOK(void, LSM_RET_VOID, inode_getlsmprop, struct inode *inode,
>          struct lsm_prop *prop)
>  LSM_HOOK(int, 0, inode_copy_up, struct dentry *src, struct cred **new)
> diff --git a/include/linux/security.h b/include/linux/security.h
> index cc9b54d95d22..0efc6a0ab56d 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -457,7 +457,7 @@ int security_inode_getsecurity(struct mnt_idmap *idmap,
>                                struct inode *inode, const char *name,
>                                void **buffer, bool alloc);
>  int security_inode_setsecurity(struct inode *inode, const char *name, const void *value, size_t size, int flags);
> -int security_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer_size);
> +int security_inode_listsecurity(struct inode *inode, char **buffer, ssize_t *remaining_size);
>  void security_inode_getlsmprop(struct inode *inode, struct lsm_prop *prop);
>  int security_inode_copy_up(struct dentry *src, struct cred **new);
>  int security_inode_copy_up_xattr(struct dentry *src, const char *name);
> @@ -1077,7 +1077,8 @@ static inline int security_inode_setsecurity(struct inode *inode, const char *na
>         return -EOPNOTSUPP;
>  }
>
> -static inline int security_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer_size)
> +static inline int security_inode_listsecurity(struct inode *inode,
> +                                       char **buffer, ssize_t *remaining_size)
>  {
>         return 0;
>  }
> diff --git a/net/socket.c b/net/socket.c
> index 9a0e720f0859..52e3670dc89b 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -562,15 +562,9 @@ static ssize_t sockfs_listxattr(struct dentry *dentry, char *buffer,
>         ssize_t len;
>         ssize_t used = 0;
>
> -       len = security_inode_listsecurity(d_inode(dentry), buffer, size);
> +       len = security_inode_listsecurity(d_inode(dentry), &buffer, &used);

And likewise wrong.

>         if (len < 0)
>                 return len;
> -       used += len;
> -       if (buffer) {
> -               if (size < used)
> -                       return -ERANGE;
> -               buffer += len;
> -       }
>
>         len = (XATTR_NAME_SOCKPROTONAME_LEN + 1);
>         used += len;
> diff --git a/security/security.c b/security/security.c
> index fb57e8fddd91..3985d040d5a9 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -2710,22 +2710,22 @@ int security_inode_setsecurity(struct inode *inode, const char *name,
>  /**
>   * security_inode_listsecurity() - List the xattr security label names
>   * @inode: inode
> - * @buffer: buffer
> - * @buffer_size: size of buffer
> + * @buffer: pointer to buffer
> + * @remaining_size: pointer to remaining size of buffer
>   *
>   * Copy the extended attribute names for the security labels associated with
> - * @inode into @buffer.  The maximum size of @buffer is specified by
> - * @buffer_size.  @buffer may be NULL to request the size of the buffer
> - * required.
> + * @inode into *(@buffer).  The remaining size of @buffer is specified by
> + * *(@remaining_size).  *(@buffer) may be NULL to request the size of the
> + * buffer required. Updates *(@buffer) and *(@remaining_size).
>   *
> - * Return: Returns number of bytes used/required on success.
> + * Return: Returns 0 on success, or -errno on failure.
>   */
>  int security_inode_listsecurity(struct inode *inode,
> -                               char *buffer, size_t buffer_size)
> +                               char **buffer, ssize_t *remaining_size)
>  {
>         if (unlikely(IS_PRIVATE(inode)))
>                 return 0;
> -       return call_int_hook(inode_listsecurity, inode, buffer, buffer_size);
> +       return call_int_hook(inode_listsecurity, inode, buffer, remaining_size);
>  }
>  EXPORT_SYMBOL(security_inode_listsecurity);
>
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index b8115df536ab..e6c98ebbf7bc 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -3612,16 +3612,12 @@ static int selinux_inode_setsecurity(struct inode *inode, const char *name,
>         return 0;
>  }
>
> -static int selinux_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer_size)
> +static int selinux_inode_listsecurity(struct inode *inode, char **buffer,
> +                               ssize_t *remaining_size)
>  {
> -       const int len = sizeof(XATTR_NAME_SELINUX);
> -
>         if (!selinux_initialized())
>                 return 0;
> -
> -       if (buffer && len <= buffer_size)
> -               memcpy(buffer, XATTR_NAME_SELINUX, len);
> -       return len;
> +       return xattr_list_one(buffer, remaining_size, XATTR_NAME_SELINUX);
>  }
>
>  static void selinux_inode_getlsmprop(struct inode *inode, struct lsm_prop *prop)
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index 99833168604e..3f7ac865532e 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -1619,17 +1619,12 @@ static int smack_inode_getsecurity(struct mnt_idmap *idmap,
>   * smack_inode_listsecurity - list the Smack attributes
>   * @inode: the object
>   * @buffer: where they go
> - * @buffer_size: size of buffer
> + * @remaining_size: size of buffer
>   */
> -static int smack_inode_listsecurity(struct inode *inode, char *buffer,
> -                                   size_t buffer_size)
> +static int smack_inode_listsecurity(struct inode *inode, char **buffer,
> +                                   ssize_t *remaining_size)
>  {
> -       int len = sizeof(XATTR_NAME_SMACK);
> -
> -       if (buffer != NULL && len <= buffer_size)
> -               memcpy(buffer, XATTR_NAME_SMACK, len);
> -
> -       return len;
> +       return xattr_list_one(buffer, remaining_size, XATTR_NAME_SMACK);
>  }
>
>  /**
> --
> 2.49.0
>

Re: [PATCH] security,fs,nfs,net: update security_inode_listsecurity() interface

[Casey Schaufler]

On 4/28/2025 8:55 AM, Stephen Smalley wrote:
> Update the security_inode_listsecurity() interface to allow
> use of the xattr_list_one() helper and update the hook
> implementations.
>
> Link: https://lore.kernel.org/selinux/20250424152822.2719-1-stephen.smalley.work@gmail.com/
>
> Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
> ---
> This patch is relative to the one linked above, which in theory is on
> vfs.fixes but doesn't appear to have been pushed when I looked.
>
>  fs/nfs/nfs4proc.c             |  9 +++++----
>  fs/xattr.c                    | 20 ++++++++------------
>  include/linux/lsm_hook_defs.h |  4 ++--
>  include/linux/security.h      |  5 +++--
>  net/socket.c                  |  8 +-------
>  security/security.c           | 16 ++++++++--------
>  security/selinux/hooks.c      | 10 +++-------
>  security/smack/smack_lsm.c    | 13 ++++---------
>  8 files changed, 34 insertions(+), 51 deletions(-)
>
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index 970f28dbf253..a1d7cb0acb5e 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -8023,12 +8023,13 @@ static int nfs4_xattr_get_nfs4_label(const struct xattr_handler *handler,
>  static ssize_t
>  nfs4_listxattr_nfs4_label(struct inode *inode, char *list, size_t list_len)
>  {
> -	int len = 0;
> +	ssize_t len = 0;
> +	int err;
>  
>  	if (nfs_server_capable(inode, NFS_CAP_SECURITY_LABEL)) {
> -		len = security_inode_listsecurity(inode, list, list_len);
> -		if (len >= 0 && list_len && len > list_len)
> -			return -ERANGE;
> +		err = security_inode_listsecurity(inode, &list, &len);
> +		if (err)
> +			len = err;
>  	}
>  	return len;
>  }
> diff --git a/fs/xattr.c b/fs/xattr.c
> index 2fc314b27120..fdd2f387bfd5 100644
> --- a/fs/xattr.c
> +++ b/fs/xattr.c
> @@ -492,9 +492,12 @@ vfs_listxattr(struct dentry *dentry, char *list, size_t size)
>  	if (inode->i_op->listxattr) {
>  		error = inode->i_op->listxattr(dentry, list, size);
>  	} else {
> -		error = security_inode_listsecurity(inode, list, size);
> -		if (size && error > size)
> -			error = -ERANGE;
> +		char *buffer = list;
> +		ssize_t len = 0;
> +
> +		error = security_inode_listsecurity(inode, &buffer, &len);
> +		if (!error)
> +			error = len;
>  	}
>  	return error;
>  }
> @@ -1469,17 +1472,10 @@ ssize_t simple_xattr_list(struct inode *inode, struct simple_xattrs *xattrs,
>  	if (err)
>  		return err;
>  
> -	err = security_inode_listsecurity(inode, buffer, remaining_size);
> -	if (err < 0)
> +	err = security_inode_listsecurity(inode, &buffer, &remaining_size);
> +	if (err)
>  		return err;
>  
> -	if (buffer) {
> -		if (remaining_size < err)
> -			return -ERANGE;
> -		buffer += err;
> -	}
> -	remaining_size -= err;
> -
>  	read_lock(&xattrs->lock);
>  	for (rbp = rb_first(&xattrs->rb_root); rbp; rbp = rb_next(rbp)) {
>  		xattr = rb_entry(rbp, struct simple_xattr, rb_node);
> diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
> index bf3bbac4e02a..3c3919dcdebc 100644
> --- a/include/linux/lsm_hook_defs.h
> +++ b/include/linux/lsm_hook_defs.h
> @@ -174,8 +174,8 @@ LSM_HOOK(int, -EOPNOTSUPP, inode_getsecurity, struct mnt_idmap *idmap,
>  	 struct inode *inode, const char *name, void **buffer, bool alloc)
>  LSM_HOOK(int, -EOPNOTSUPP, inode_setsecurity, struct inode *inode,
>  	 const char *name, const void *value, size_t size, int flags)
> -LSM_HOOK(int, 0, inode_listsecurity, struct inode *inode, char *buffer,
> -	 size_t buffer_size)
> +LSM_HOOK(int, 0, inode_listsecurity, struct inode *inode, char **buffer,
> +	 ssize_t *remaining_size)

How about "rem", "rsize" or some other name instead of the overly long
"remaining_size_"? 

>  LSM_HOOK(void, LSM_RET_VOID, inode_getlsmprop, struct inode *inode,
>  	 struct lsm_prop *prop)
>  LSM_HOOK(int, 0, inode_copy_up, struct dentry *src, struct cred **new)
> diff --git a/include/linux/security.h b/include/linux/security.h
> index cc9b54d95d22..0efc6a0ab56d 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -457,7 +457,7 @@ int security_inode_getsecurity(struct mnt_idmap *idmap,
>  			       struct inode *inode, const char *name,
>  			       void **buffer, bool alloc);
>  int security_inode_setsecurity(struct inode *inode, const char *name, const void *value, size_t size, int flags);
> -int security_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer_size);
> +int security_inode_listsecurity(struct inode *inode, char **buffer, ssize_t *remaining_size);
>  void security_inode_getlsmprop(struct inode *inode, struct lsm_prop *prop);
>  int security_inode_copy_up(struct dentry *src, struct cred **new);
>  int security_inode_copy_up_xattr(struct dentry *src, const char *name);
> @@ -1077,7 +1077,8 @@ static inline int security_inode_setsecurity(struct inode *inode, const char *na
>  	return -EOPNOTSUPP;
>  }
>  
> -static inline int security_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer_size)
> +static inline int security_inode_listsecurity(struct inode *inode,
> +					char **buffer, ssize_t *remaining_size)
>  {
>  	return 0;
>  }
> diff --git a/net/socket.c b/net/socket.c
> index 9a0e720f0859..52e3670dc89b 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -562,15 +562,9 @@ static ssize_t sockfs_listxattr(struct dentry *dentry, char *buffer,
>  	ssize_t len;
>  	ssize_t used = 0;
>  
> -	len = security_inode_listsecurity(d_inode(dentry), buffer, size);
> +	len = security_inode_listsecurity(d_inode(dentry), &buffer, &used);
>  	if (len < 0)
>  		return len;
> -	used += len;
> -	if (buffer) {
> -		if (size < used)
> -			return -ERANGE;
> -		buffer += len;
> -	}
>  
>  	len = (XATTR_NAME_SOCKPROTONAME_LEN + 1);
>  	used += len;
> diff --git a/security/security.c b/security/security.c
> index fb57e8fddd91..3985d040d5a9 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -2710,22 +2710,22 @@ int security_inode_setsecurity(struct inode *inode, const char *name,
>  /**
>   * security_inode_listsecurity() - List the xattr security label names
>   * @inode: inode
> - * @buffer: buffer
> - * @buffer_size: size of buffer
> + * @buffer: pointer to buffer
> + * @remaining_size: pointer to remaining size of buffer
>   *
>   * Copy the extended attribute names for the security labels associated with
> - * @inode into @buffer.  The maximum size of @buffer is specified by
> - * @buffer_size.  @buffer may be NULL to request the size of the buffer
> - * required.
> + * @inode into *(@buffer).  The remaining size of @buffer is specified by
> + * *(@remaining_size).  *(@buffer) may be NULL to request the size of the
> + * buffer required. Updates *(@buffer) and *(@remaining_size).
>   *
> - * Return: Returns number of bytes used/required on success.
> + * Return: Returns 0 on success, or -errno on failure.
>   */
>  int security_inode_listsecurity(struct inode *inode,
> -				char *buffer, size_t buffer_size)
> +				char **buffer, ssize_t *remaining_size)
>  {
>  	if (unlikely(IS_PRIVATE(inode)))
>  		return 0;
> -	return call_int_hook(inode_listsecurity, inode, buffer, buffer_size);
> +	return call_int_hook(inode_listsecurity, inode, buffer, remaining_size);
>  }
>  EXPORT_SYMBOL(security_inode_listsecurity);
>  
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index b8115df536ab..e6c98ebbf7bc 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -3612,16 +3612,12 @@ static int selinux_inode_setsecurity(struct inode *inode, const char *name,
>  	return 0;
>  }
>  
> -static int selinux_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer_size)
> +static int selinux_inode_listsecurity(struct inode *inode, char **buffer,
> +				ssize_t *remaining_size)
>  {
> -	const int len = sizeof(XATTR_NAME_SELINUX);
> -
>  	if (!selinux_initialized())
>  		return 0;
> -
> -	if (buffer && len <= buffer_size)
> -		memcpy(buffer, XATTR_NAME_SELINUX, len);
> -	return len;
> +	return xattr_list_one(buffer, remaining_size, XATTR_NAME_SELINUX);
>  }
>  
>  static void selinux_inode_getlsmprop(struct inode *inode, struct lsm_prop *prop)
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index 99833168604e..3f7ac865532e 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -1619,17 +1619,12 @@ static int smack_inode_getsecurity(struct mnt_idmap *idmap,
>   * smack_inode_listsecurity - list the Smack attributes
>   * @inode: the object
>   * @buffer: where they go
> - * @buffer_size: size of buffer
> + * @remaining_size: size of buffer
>   */
> -static int smack_inode_listsecurity(struct inode *inode, char *buffer,
> -				    size_t buffer_size)
> +static int smack_inode_listsecurity(struct inode *inode, char **buffer,
> +				    ssize_t *remaining_size)
>  {
> -	int len = sizeof(XATTR_NAME_SMACK);
> -
> -	if (buffer != NULL && len <= buffer_size)
> -		memcpy(buffer, XATTR_NAME_SMACK, len);
> -
> -	return len;
> +	return xattr_list_one(buffer, remaining_size, XATTR_NAME_SMACK);
>  }
>  
>  /**

Re: [PATCH] security,fs,nfs,net: update security_inode_listsecurity() interface

[Stephen Smalley]

On Mon, Apr 28, 2025 at 12:17 PM Casey Schaufler <casey@schaufler-ca.com> wrote:
>
> On 4/28/2025 8:55 AM, Stephen Smalley wrote:
> > Update the security_inode_listsecurity() interface to allow
> > use of the xattr_list_one() helper and update the hook
> > implementations.
> >
> > Link: https://lore.kernel.org/selinux/20250424152822.2719-1-stephen.smalley.work@gmail.com/
> >
> > Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
> > ---
> > This patch is relative to the one linked above, which in theory is on
> > vfs.fixes but doesn't appear to have been pushed when I looked.
>
> > diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
> > index bf3bbac4e02a..3c3919dcdebc 100644
> > --- a/include/linux/lsm_hook_defs.h
> > +++ b/include/linux/lsm_hook_defs.h
> > @@ -174,8 +174,8 @@ LSM_HOOK(int, -EOPNOTSUPP, inode_getsecurity, struct mnt_idmap *idmap,
> >        struct inode *inode, const char *name, void **buffer, bool alloc)
> >  LSM_HOOK(int, -EOPNOTSUPP, inode_setsecurity, struct inode *inode,
> >        const char *name, const void *value, size_t size, int flags)
> > -LSM_HOOK(int, 0, inode_listsecurity, struct inode *inode, char *buffer,
> > -      size_t buffer_size)
> > +LSM_HOOK(int, 0, inode_listsecurity, struct inode *inode, char **buffer,
> > +      ssize_t *remaining_size)
>
> How about "rem", "rsize" or some other name instead of the overly long
> "remaining_size_"?

I don't especially care either way but was just being consistent with
the xattr_list_one() code.

Re: [PATCH] security,fs,nfs,net: update security_inode_listsecurity() interface

[Casey Schaufler]

On 4/28/2025 9:23 AM, Stephen Smalley wrote:
> On Mon, Apr 28, 2025 at 12:17 PM Casey Schaufler <casey@schaufler-ca.com> wrote:
>> On 4/28/2025 8:55 AM, Stephen Smalley wrote:
>>> Update the security_inode_listsecurity() interface to allow
>>> use of the xattr_list_one() helper and update the hook
>>> implementations.
>>>
>>> Link: https://lore.kernel.org/selinux/20250424152822.2719-1-stephen.smalley.work@gmail.com/
>>>
>>> Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
>>> ---
>>> This patch is relative to the one linked above, which in theory is on
>>> vfs.fixes but doesn't appear to have been pushed when I looked.
>>> diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
>>> index bf3bbac4e02a..3c3919dcdebc 100644
>>> --- a/include/linux/lsm_hook_defs.h
>>> +++ b/include/linux/lsm_hook_defs.h
>>> @@ -174,8 +174,8 @@ LSM_HOOK(int, -EOPNOTSUPP, inode_getsecurity, struct mnt_idmap *idmap,
>>>        struct inode *inode, const char *name, void **buffer, bool alloc)
>>>  LSM_HOOK(int, -EOPNOTSUPP, inode_setsecurity, struct inode *inode,
>>>        const char *name, const void *value, size_t size, int flags)
>>> -LSM_HOOK(int, 0, inode_listsecurity, struct inode *inode, char *buffer,
>>> -      size_t buffer_size)
>>> +LSM_HOOK(int, 0, inode_listsecurity, struct inode *inode, char **buffer,
>>> +      ssize_t *remaining_size)
>> How about "rem", "rsize" or some other name instead of the overly long
>> "remaining_size_"?
> I don't especially care either way but was just being consistent with
> the xattr_list_one() code.

Sigh. Then I'd leave it as is.