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ef78fdc472
In apparmor_path_rename(), when handling RENAME_EXCHANGE, the
cond_exchange structure is supposed to carry the attributes of the
*new* dentry (since it is used to authorize moving new_dentry to the
old location). However, line 412 reads:
vfsuid = i_uid_into_vfsuid(idmap, d_backing_inode(old_dentry));
This fetches the uid of old_dentry instead of new_dentry. As a result,
the RENAME_EXCHANGE permission check uses the wrong file owner, which
can allow a rename that should be denied (if old_dentry's owner has
more privileges) or deny one that should be allowed.
Note that cond_exchange.mode on the line above correctly uses
new_dentry. Only the uid lookup is wrong.
Fix by changing old_dentry to new_dentry in the i_uid_into_vfsuid call.
Fixes: 5e26a01e56 ("apparmor: use type safe idmapping helpers")
Reviewed-by: Georgia Garcia <georgia.garcia@canonical.com>
Signed-off-by: Dudu Lu <phx0fer@gmail.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>