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authorSachin Prabhu <sprabhu@redhat.com>2016-05-17 18:20:13 -0500
committerSasha Levin <sasha.levin@oracle.com>2016-06-06 19:11:09 -0400
commit4ccd5ccb1cbd83556ee9d02f69a48e109aaaca6d (patch)
treec8c2c5565a30b54192dceb94ed39e729f4564afe
parent50c860767d3c448c246d764488d3d581e70bbf2e (diff)
cifs: Create dedicated keyring for spnego operations
[ Upstream commit b74cb9a80268be5c80cf4c87c74debf0ff2129ac ] The session key is the default keyring set for request_key operations. This session key is revoked when the user owning the session logs out. Any long running daemon processes started by this session ends up with revoked session keyring which prevents these processes from using the request_key mechanism from obtaining the krb5 keys. The problem has been reported by a large number of autofs users. The problem is also seen with multiuser mounts where the share may be used by processes run by a user who has since logged out. A reproducer using automount is available on the Red Hat bz. The patch creates a new keyring which is used to cache cifs spnego upcalls. Red Hat bz: 1267754 Signed-off-by: Sachin Prabhu <sprabhu@redhat.com> Reported-by: Scott Mayhew <smayhew@redhat.com> Reviewed-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com> CC: Stable <stable@vger.kernel.org> Signed-off-by: Steve French <smfrench@gmail.com> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
-rw-r--r--fs/cifs/cifs_spnego.c67
-rw-r--r--fs/cifs/cifsfs.c4
-rw-r--r--fs/cifs/cifsproto.h2
3 files changed, 71 insertions, 2 deletions
diff --git a/fs/cifs/cifs_spnego.c b/fs/cifs/cifs_spnego.c
index f4cf200b3c76..79450fa66d16 100644
--- a/fs/cifs/cifs_spnego.c
+++ b/fs/cifs/cifs_spnego.c
@@ -24,10 +24,13 @@
#include <linux/string.h>
#include <keys/user-type.h>
#include <linux/key-type.h>
+#include <linux/keyctl.h>
#include <linux/inet.h>
#include "cifsglob.h"
#include "cifs_spnego.h"
#include "cifs_debug.h"
+#include "cifsproto.h"
+static const struct cred *spnego_cred;
/* create a new cifs key */
static int
@@ -102,6 +105,7 @@ cifs_get_spnego_key(struct cifs_ses *sesInfo)
size_t desc_len;
struct key *spnego_key;
const char *hostname = server->hostname;
+ const struct cred *saved_cred;
/* length of fields (with semicolons): ver=0xyz ip4=ipaddress
host=hostname sec=mechanism uid=0xFF user=username */
@@ -163,7 +167,9 @@ cifs_get_spnego_key(struct cifs_ses *sesInfo)
sprintf(dp, ";pid=0x%x", current->pid);
cifs_dbg(FYI, "key description = %s\n", description);
+ saved_cred = override_creds(spnego_cred);
spnego_key = request_key(&cifs_spnego_key_type, description, "");
+ revert_creds(saved_cred);
#ifdef CONFIG_CIFS_DEBUG2
if (cifsFYI && !IS_ERR(spnego_key)) {
@@ -177,3 +183,64 @@ out:
kfree(description);
return spnego_key;
}
+
+int
+init_cifs_spnego(void)
+{
+ struct cred *cred;
+ struct key *keyring;
+ int ret;
+
+ cifs_dbg(FYI, "Registering the %s key type\n",
+ cifs_spnego_key_type.name);
+
+ /*
+ * Create an override credential set with special thread keyring for
+ * spnego upcalls.
+ */
+
+ cred = prepare_kernel_cred(NULL);
+ if (!cred)
+ return -ENOMEM;
+
+ keyring = keyring_alloc(".cifs_spnego",
+ GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, cred,
+ (KEY_POS_ALL & ~KEY_POS_SETATTR) |
+ KEY_USR_VIEW | KEY_USR_READ,
+ KEY_ALLOC_NOT_IN_QUOTA, NULL);
+ if (IS_ERR(keyring)) {
+ ret = PTR_ERR(keyring);
+ goto failed_put_cred;
+ }
+
+ ret = register_key_type(&cifs_spnego_key_type);
+ if (ret < 0)
+ goto failed_put_key;
+
+ /*
+ * instruct request_key() to use this special keyring as a cache for
+ * the results it looks up
+ */
+ set_bit(KEY_FLAG_ROOT_CAN_CLEAR, &keyring->flags);
+ cred->thread_keyring = keyring;
+ cred->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
+ spnego_cred = cred;
+
+ cifs_dbg(FYI, "cifs spnego keyring: %d\n", key_serial(keyring));
+ return 0;
+
+failed_put_key:
+ key_put(keyring);
+failed_put_cred:
+ put_cred(cred);
+ return ret;
+}
+
+void
+exit_cifs_spnego(void)
+{
+ key_revoke(spnego_cred->thread_keyring);
+ unregister_key_type(&cifs_spnego_key_type);
+ put_cred(spnego_cred);
+ cifs_dbg(FYI, "Unregistered %s key type\n", cifs_spnego_key_type.name);
+}
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 9d7996e8e793..3e924abdd969 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -1249,7 +1249,7 @@ init_cifs(void)
goto out_destroy_mids;
#ifdef CONFIG_CIFS_UPCALL
- rc = register_key_type(&cifs_spnego_key_type);
+ rc = init_cifs_spnego();
if (rc)
goto out_destroy_request_bufs;
#endif /* CONFIG_CIFS_UPCALL */
@@ -1272,7 +1272,7 @@ out_init_cifs_idmap:
out_register_key_type:
#endif
#ifdef CONFIG_CIFS_UPCALL
- unregister_key_type(&cifs_spnego_key_type);
+ exit_cifs_spnego();
out_destroy_request_bufs:
#endif
cifs_destroy_request_bufs();
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index c31ce98c1704..5b868060eab8 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -60,6 +60,8 @@ do { \
} while (0)
extern int init_cifs_idmap(void);
extern void exit_cifs_idmap(void);
+extern int init_cifs_spnego(void);
+extern void exit_cifs_spnego(void);
extern char *build_path_from_dentry(struct dentry *);
extern char *cifs_build_path_to_root(struct smb_vol *vol,
struct cifs_sb_info *cifs_sb,