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Subject[PATCH 1/6] keys: Fix request_key() lack of Link perm check on found key
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The request_key() syscall allows a process to gain access to the 'possessor'
permits of any key that grants it Search permission by virtue of request_key()
not checking whether a key it finds grants Link permission to the caller.

Signed-off-by: David Howells <dhowells@redhat.com>
---

security/keys/request_key.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index e3653c6f85c6..d204d7c0152e 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -559,6 +559,16 @@ struct key *request_key_and_link(struct key_type *type,
key_ref = search_process_keyrings(&ctx);

if (!IS_ERR(key_ref)) {
+ if (dest_keyring) {
+ ret = key_task_permission(key_ref, current_cred(),
+ KEY_NEED_LINK);
+ if (ret < 0) {
+ key_ref_put(key_ref);
+ key = ERR_PTR(ret);
+ goto error_free;
+ }
+ }
+
key = key_ref_to_ptr(key_ref);
if (dest_keyring) {
ret = key_link(dest_keyring, key);
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