From: Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx>
Define (global) data structures to store ids, uids and gids, to which a
SID maps. There are two separate trees, one for SID/uid and another one
for SID/gid.
A new type of key, cifs_idmap_key_type, is used.
Keys are instantiated and searched using credential of the root by
overriding and restoring the credentials of the caller requesting the key.
Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@xxxxxxxxx>
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/cifs/cifsacl.c | 138 +++++++++++++++++++++++++++++++++++++++++++++++++++
fs/cifs/cifsfs.c | 7 +++
fs/cifs/cifsglob.h | 5 ++
fs/cifs/cifsproto.h | 3 +
4 files changed, 153 insertions(+), 0 deletions(-)
diff --git a/fs/cifs/cifsacl.c b/fs/cifs/cifsacl.c
index beeebf1..cad8d9b 100644
--- a/fs/cifs/cifsacl.c
+++ b/fs/cifs/cifsacl.c
@@ -23,6 +23,10 @@
#include <linux/fs.h>
#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/keyctl.h>
+#include <linux/key-type.h>
+#include <keys/user-type.h>
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifsacl.h"
@@ -50,6 +54,140 @@ static const struct cifs_sid sid_authusers = {
/* group users */
static const struct cifs_sid sid_user = {1, 2 , {0, 0, 0, 0, 0, 5}, {} };
+static const struct cred *root_cred;
+
+/*
+ * Run idmap cache shrinker.
+ */
+static int
+cifs_idmap_shrinker(struct shrinker *shrink, int nr_to_scan, gfp_t gfp_mask)
+{
+ /* Use a pruning scheme in a subsequent patch instead */
+ cifs_destroy_idmaptrees();
+ return 0;
+}
+
+static struct shrinker cifs_shrinker = {
+ .shrink = cifs_idmap_shrinker,
+ .seeks = DEFAULT_SEEKS,
+};
+
+static int
+cifs_idmap_key_instantiate(struct key *key, const void *data, size_t datalen)
+{
+ char *payload;
+
+ payload = kmalloc(datalen, GFP_KERNEL);
+ if (!payload)
+ return -ENOMEM;
+
+ memcpy(payload, data, datalen);
+ key->payload.data = payload;
+ return 0;
+}
+
+static inline void
+cifs_idmap_key_destroy(struct key *key)
+{
+ kfree(key->payload.data);
+}
+
+static
+struct key_type cifs_idmap_key_type = {
+ .name = "cifs.cifs_idmap",
+ .instantiate = cifs_idmap_key_instantiate,
+ .destroy = cifs_idmap_key_destroy,
+ .describe = user_describe,
+ .match = user_match,
+};
+
+int
+init_cifs_idmap(void)
+{
+ struct cred *cred;
+ struct key *keyring;
+ int ret;
+
+ cFYI(1, "Registering the %s key type\n", cifs_idmap_key_type.name);
+
+ /* create an override credential set with a special thread keyring in
+ * which requests are cached
+ *
+ * this is used to prevent malicious redirections from being installed
+ * with add_key().
+ */
+ cred = prepare_kernel_cred(NULL);
+ if (!cred)
+ return -ENOMEM;
+
+ keyring = key_alloc(&key_type_keyring, ".cifs_idmap", 0, 0, cred,
+ (KEY_POS_ALL & ~KEY_POS_SETATTR) |
+ KEY_USR_VIEW | KEY_USR_READ,
+ KEY_ALLOC_NOT_IN_QUOTA);
+ if (IS_ERR(keyring)) {
+ ret = PTR_ERR(keyring);
+ goto failed_put_cred;
+ }
+
+ ret = key_instantiate_and_link(keyring, NULL, 0, NULL, NULL);
+ if (ret < 0)
+ goto failed_put_key;
+
+ ret = register_key_type(&cifs_idmap_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 */
+ cred->thread_keyring = keyring;
+ cred->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
+ root_cred = cred;
+
+ spin_lock_init(&siduidlock);
+ uidtree = RB_ROOT;
+ spin_lock_init(&sidgidlock);
+ gidtree = RB_ROOT;
+
+ register_shrinker(&cifs_shrinker);
+
+ cFYI(1, "cifs idmap 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_idmap(void)
+{
+ key_revoke(root_cred->thread_keyring);
+ unregister_key_type(&cifs_idmap_key_type);
+ put_cred(root_cred);
+ unregister_shrinker(&cifs_shrinker);
+ cFYI(1, "Unregistered %s key type\n", cifs_idmap_key_type.name);
+}
+
+void
+cifs_destroy_idmaptrees(void)
+{
+ struct rb_root *root;
+ struct rb_node *node;
+
+ root = &uidtree;
+ spin_lock(&siduidlock);
+ while ((node = rb_first(root)))
+ rb_erase(node, root);
+ spin_unlock(&siduidlock);
+
+ root = &gidtree;
+ spin_lock(&sidgidlock);
+ while ((node = rb_first(root)))
+ rb_erase(node, root);
+ spin_unlock(&sidgidlock);
+}
int match_sid(struct cifs_sid *ctsid)
{
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 5c412b3..31fb7fd 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -1040,11 +1040,16 @@ init_cifs(void)
rc = register_key_type(&cifs_spnego_key_type);
if (rc)
goto out_unregister_filesystem;
+ rc = init_cifs_idmap();
+ if (rc)
+ goto out_unregister_keytype;
#endif
return 0;
#ifdef CONFIG_CIFS_UPCALL
+out_unregister_keytype:
+ unregister_key_type(&cifs_spnego_key_type);
out_unregister_filesystem:
unregister_filesystem(&cifs_fs_type);
#endif
@@ -1071,6 +1076,8 @@ exit_cifs(void)
cifs_dfs_release_automount_timer();
#endif
#ifdef CONFIG_CIFS_UPCALL
+ cifs_destroy_idmaptrees();
+ exit_cifs_idmap();
unregister_key_type(&cifs_spnego_key_type);
#endif
unregister_filesystem(&cifs_fs_type);
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index a5d1106..84aaff5 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -830,6 +830,11 @@ GLOBAL_EXTERN unsigned int cifs_max_pending; /* MAX requests at once to server*/
/* reconnect after this many failed echo attempts */
GLOBAL_EXTERN unsigned short echo_retries;
+GLOBAL_EXTERN struct rb_root uidtree;
+GLOBAL_EXTERN struct rb_root gidtree;
+GLOBAL_EXTERN spinlock_t siduidlock;
+GLOBAL_EXTERN spinlock_t sidgidlock;
+
void cifs_oplock_break(struct work_struct *work);
void cifs_oplock_break_get(struct cifsFileInfo *cfile);
void cifs_oplock_break_put(struct cifsFileInfo *cfile);
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 8096f27..50e2141 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -53,6 +53,9 @@ do { \
cFYI(1, "CIFS VFS: leaving %s (xid = %d) rc = %d", \
__func__, curr_xid, (int)rc); \
} while (0)
+extern int init_cifs_idmap(void);
+extern void exit_cifs_idmap(void);
+extern void cifs_destroy_idmaptrees(void);
extern char *build_path_from_dentry(struct dentry *);
extern char *cifs_build_path_to_root(struct cifs_sb_info *cifs_sb,
struct cifsTconInfo *tcon);
--
1.6.0.2
--
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