[PATCH v2 18/28] capability: privileged_wrt_inode_uidgid(): handle fsid mappings

Christian Brauner
2020-02-14T18:38:11Z

Switch privileged_wrt_inode_uidgid() to lookup fsids in the fsid mappings. If
no fsid mappings are setup the behavior is unchanged, i.e. fsids are looked up
in the id mappings.

Filesystems that share a superblock in all user namespaces they are mounted in
will retain their old semantics even with the introduction of fsidmappings.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
/* v2 */
unchanged
---
kernel/capability.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/kernel/capability.c b/kernel/capability.c
index 1444f3954d75..2b0c1dc992e2 100644
--- a/kernel/capability.c
+++ b/kernel/capability.c
@@ -19,6 +19,8 @@
#include <linux/pid_namespace.h>
#include <linux/user_namespace.h>
#include <linux/uaccess.h>
+#include <linux/fsuidgid.h>
+#include <linux/fs.h>

/*
* Leveraged for setting/resetting capabilities
@@ -486,8 +488,12 @@ EXPORT_SYMBOL(file_ns_capable);
*/
bool privileged_wrt_inode_uidgid(struct user_namespace *ns, const struct inode *inode)
{
- return kuid_has_mapping(ns, inode->i_uid) &&
- kgid_has_mapping(ns, inode->i_gid);
+ if (is_userns_visible(inode->i_sb->s_iflags))
+ return kuid_has_mapping(ns, inode->i_uid) &&
+ kgid_has_mapping(ns, inode->i_gid);
+
+ return kfsuid_has_mapping(ns, inode->i_uid) &&
+ kfsgid_has_mapping(ns, inode->i_gid);
}

/**
--
2.25.0