[PATCH 10/29] ubifs: Massage ubifs_listxattr() for encryption context

From: Richard Weinberger
Date: Sun Nov 13 2016 - 16:25:56 EST


We have to make sure that we don't expose our internal
crypto context to userspace.

Signed-off-by: Richard Weinberger <richard@xxxxxx>
---
fs/ubifs/xattr.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/fs/ubifs/xattr.c b/fs/ubifs/xattr.c
index 95a16028bbdb..77ffc9788f45 100644
--- a/fs/ubifs/xattr.c
+++ b/fs/ubifs/xattr.c
@@ -397,6 +397,20 @@ ssize_t ubifs_xattr_get(struct inode *host, const char *name, void *buf,
return err;
}

+static bool xattr_visible(const char *name)
+{
+ /* File encryption related xattrs are for internal use only */
+ if (strcmp(name, UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT) == 0)
+ return false;
+
+ /* Show trusted namespace only for "power" users */
+ if (strncmp(name, XATTR_TRUSTED_PREFIX,
+ XATTR_TRUSTED_PREFIX_LEN) == 0 && !capable(CAP_SYS_ADMIN))
+ return false;
+
+ return true;
+}
+
ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)
{
union ubifs_key key;
@@ -432,10 +446,7 @@ ssize_t ubifs_listxattr(struct dentry *dentry, char *buffer, size_t size)
nm.name = xent->name;
nm.len = le16_to_cpu(xent->nlen);

- /* Show trusted namespace only for "power" users */
- if (strncmp(xent->name, XATTR_TRUSTED_PREFIX,
- XATTR_TRUSTED_PREFIX_LEN) ||
- capable(CAP_SYS_ADMIN)) {
+ if (xattr_visible(xent->name)) {
memcpy(buffer + written, nm.name, nm.len + 1);
written += nm.len + 1;
}
--
2.7.3