* [RFC PATCH 4/6] ksmbd: map user and group ids to Windows SIDs through user space
@ 2026-11-10 9:02 Jan Koester
0 siblings, 0 replies; 2+ messages in thread
From: Jan Koester @ 2026-11-10 9:02 UTC (permalink / raw)
To: linkinjeon, smfrench
Cc: senozhatsky, tom, chenxiaosong, brauner, linux-cifs,
linux-fsdevel, samba-technical, linux-kernel
A domain account has a SID of its own (its objectSid) that Windows
clients use for owners and ACL entries, while files and credentials
carry the account's uid or gid -- a classic id, a UUID or a GUID. ksmbd
shows the ids as S-1-22 SIDs or its server domain SID + uid, which
Windows can't relate to the domain's accounts, and SIDs a client sets
for domain accounts don't map back at all.
Let user space translate in both directions. A user space that sets
KSMBD_GLOBAL_FLAG_SID_MAP at startup gets KSMBD_EVENT_SID_MAP_REQUEST
for the SID of an id ksmbd shows as owner, group or ACL entry, and for
the id of a domain account SID (S-1-5-21-..., outside the server's own
domain) a client sets -- for any account, logged in or not. Answers
are cached: mappings for five minutes, "no mapping" for one minute; an
answer user space couldn't give (its directory unreachable) is never
cached. Ids without a mapping keep the SIDs ksmbd gave them so far.
Showing a descriptor never fails on a missing mapping. Setting one
fails instead of being applied in part: STATUS_NO_LOGON_SERVERS when
user space can't answer, STATUS_INVALID_OWNER or
STATUS_INVALID_PRIMARY_GROUP for a domain SID that maps to no user or
group, which used to be ignored silently. ACEs for groups become
ACL_GROUP entries of the POSIX ACL.
A session matched only its user's own SID against the ACEs of a stored
descriptor. Give the session user the SIDs of its groups too, mapped
and unmapped, like a Windows access token, built at login, and compare
SIDs exactly: compare_sids() accepts a prefix.
Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Jan Koester <jan.koester@tuxist.de>
---
fs/smb/server/Makefile | 2 +-
fs/smb/server/idmap.c | 320 +++++++++++++++++++++++++++++++
fs/smb/server/idmap.h | 25 +++
fs/smb/server/ksmbd_netlink.h | 50 +++++
fs/smb/server/mgmt/user_config.c | 5 +
fs/smb/server/mgmt/user_config.h | 5 +
fs/smb/server/server.c | 2 +
fs/smb/server/smb2pdu.c | 11 +-
fs/smb/server/smbacl.c | 190 +++++++++++++++++-
fs/smb/server/smbacl.h | 16 +-
fs/smb/server/transport_ipc.c | 60 ++++++
fs/smb/server/transport_ipc.h | 3 +
12 files changed, 672 insertions(+), 17 deletions(-)
create mode 100644 fs/smb/server/idmap.c
create mode 100644 fs/smb/server/idmap.h
diff --git a/fs/smb/server/Makefile b/fs/smb/server/Makefile
index a3e9306055..39a6ec4ca9 100644
--- a/fs/smb/server/Makefile
+++ b/fs/smb/server/Makefile
@@ -8,7 +8,7 @@ ksmbd-y := unicode.o auth.o vfs.o vfs_cache.o server.o ndr.o \
misc.o oplock.o connection.o ksmbd_work.o crypto_ctx.o \
mgmt/ksmbd_ida.o mgmt/user_config.o mgmt/share_config.o \
mgmt/tree_connect.o mgmt/user_session.o smb_common.o \
- transport_tcp.o transport_ipc.o smbacl.o smb2pdu.o \
+ transport_tcp.o transport_ipc.o smbacl.o idmap.o smb2pdu.o \
smb2ops.o smb2misc.o ksmbd_spnego_negtokeninit.asn1.o \
ksmbd_spnego_negtokentarg.asn1.o asn1.o compress.o
diff --git a/fs/smb/server/idmap.c b/fs/smb/server/idmap.c
new file mode 100644
index 0000000000..8ea83b3e93
--- /dev/null
+++ b/fs/smb/server/idmap.c
@@ -0,0 +1,320 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * The Windows SIDs of user and group ids, as user space maps them.
+ *
+ * A domain account has a SID of its own (its objectSid) that Windows uses
+ * for owners and ACL entries, while files and credentials carry the
+ * account's uid or gid -- a classic id, a UUID or a GUID. ksmbd asks user
+ * space (KSMBD_EVENT_SID_MAP_REQUEST) for every owner and ACL entry it
+ * shows or sets, also of accounts that aren't logged in, and keeps the
+ * answers here for a while: mappings for IDMAP_TTL, "no such mapping" for
+ * IDMAP_NEG_TTL. An answer that user space couldn't give (its directory
+ * unreachable) is never cached. Only SIDs of the form S-1-5-21-... (a
+ * domain's accounts) outside the server's own domain are looked up.
+ */
+
+#include <linux/hashtable.h>
+#include <linux/jhash.h>
+#include <linux/jiffies.h>
+#include <linux/list.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+#include "glob.h"
+#include "idmap.h"
+#include "ksmbd_netlink.h"
+#include "server.h"
+#include "smbacl.h"
+#include "transport_ipc.h"
+
+#define IDMAP_TTL (300 * HZ)
+#define IDMAP_NEG_TTL (60 * HZ)
+#define IDMAP_MAX 4096
+#define IDMAP_BITS 9
+
+/*
+ * A mapping (id and SID, in both tables) or a negative entry for an id or
+ * a SID (in that one table).
+ */
+struct idmap_entry {
+ struct list_head lru;
+ struct hlist_node by_id;
+ struct hlist_node by_sid;
+ bool has_id;
+ bool has_sid;
+ bool group;
+ struct __kernel_uid_r id;
+ struct smb_sid sid;
+ unsigned long expires;
+};
+
+static DEFINE_HASHTABLE(idmap_by_id, IDMAP_BITS);
+static DEFINE_HASHTABLE(idmap_by_sid, IDMAP_BITS);
+static LIST_HEAD(idmap_lru);
+static unsigned int idmap_count;
+static DEFINE_SPINLOCK(idmap_lock);
+
+static const u8 nt_authority[NUM_AUTHS] = {0, 0, 0, 0, 0, 5};
+
+static size_t sid_size(const struct smb_sid *sid)
+{
+ return CIFS_SID_BASE_SIZE + sizeof(__le32) * sid->num_subauth;
+}
+
+static bool sid_eq(const struct smb_sid *a, const struct smb_sid *b)
+{
+ return a->num_subauth == b->num_subauth && !memcmp(a, b, sid_size(a));
+}
+
+/* only the member type selects, the rest zero: comparable with memcmp() */
+static void id_norm(struct __kernel_uid_r *out, const struct __kernel_uid_r *in)
+{
+ memset(out, 0, sizeof(*out));
+ out->type = in->type;
+ if (in->type == UID_R_LEGACY)
+ out->legacy = in->legacy;
+ else if (in->type == UID_R_UUID || in->type == UID_R_GUID)
+ memcpy(out->uuid, in->uuid, sizeof(out->uuid));
+}
+
+static u32 id_hash(bool group, const struct __kernel_uid_r *id)
+{
+ return jhash(id, sizeof(*id), group);
+}
+
+static u32 sid_hash(const struct smb_sid *sid)
+{
+ return jhash(sid, sid_size(sid), 0);
+}
+
+bool ksmbd_idmap_enabled(void)
+{
+ return server_conf.flags & KSMBD_GLOBAL_FLAG_SID_MAP;
+}
+
+/* S-1-5-21-..., not of the server's own domain */
+bool ksmbd_idmap_sid_mappable(const struct smb_sid *sid)
+{
+ const struct smb_sid *own = &server_conf.domain_sid;
+
+ if (sid->revision != 1 || sid->num_subauth < 2 ||
+ sid->num_subauth > SID_MAX_SUB_AUTHORITIES ||
+ memcmp(sid->authority, nt_authority, NUM_AUTHS) ||
+ le32_to_cpu(sid->sub_auth[0]) != 21)
+ return false;
+ return !(sid->num_subauth == own->num_subauth + 1 &&
+ !memcmp(sid->sub_auth, own->sub_auth,
+ sizeof(__le32) * own->num_subauth));
+}
+
+/* with idmap_lock */
+static void idmap_unlink(struct idmap_entry *e)
+{
+ list_del(&e->lru);
+ if (e->has_id)
+ hash_del(&e->by_id);
+ if (e->has_sid)
+ hash_del(&e->by_sid);
+ idmap_count--;
+ kfree(e);
+}
+
+/* a copy of the cached entry for the id (true), or false */
+static bool idmap_find_id(bool group, const struct __kernel_uid_r *id,
+ struct idmap_entry *out)
+{
+ struct idmap_entry *e;
+ bool found = false;
+
+ spin_lock(&idmap_lock);
+ hash_for_each_possible(idmap_by_id, e, by_id, id_hash(group, id)) {
+ if (e->group != group || memcmp(&e->id, id, sizeof(*id)))
+ continue;
+ if (time_after(jiffies, e->expires)) {
+ idmap_unlink(e);
+ break;
+ }
+ list_move(&e->lru, &idmap_lru);
+ *out = *e;
+ found = true;
+ break;
+ }
+ spin_unlock(&idmap_lock);
+ return found;
+}
+
+static bool idmap_find_sid(const struct smb_sid *sid, struct idmap_entry *out)
+{
+ struct idmap_entry *e;
+ bool found = false;
+
+ spin_lock(&idmap_lock);
+ hash_for_each_possible(idmap_by_sid, e, by_sid, sid_hash(sid)) {
+ if (!sid_eq(&e->sid, sid))
+ continue;
+ if (time_after(jiffies, e->expires)) {
+ idmap_unlink(e);
+ break;
+ }
+ list_move(&e->lru, &idmap_lru);
+ *out = *e;
+ found = true;
+ break;
+ }
+ spin_unlock(&idmap_lock);
+ return found;
+}
+
+/*
+ * Cache a mapping (id and sid), or that id (sid NULL) or sid (id NULL) has
+ * none. It replaces what was cached for the same id or SID.
+ */
+static void idmap_add(bool group, const struct __kernel_uid_r *id,
+ const struct smb_sid *sid)
+{
+ struct idmap_entry *e, *old;
+ struct hlist_node *tmp;
+
+ e = kzalloc_obj(struct idmap_entry, KSMBD_DEFAULT_GFP);
+ if (!e)
+ return;
+ e->group = group;
+ e->has_id = id;
+ e->has_sid = sid;
+ if (id)
+ e->id = *id;
+ if (sid)
+ memcpy(&e->sid, sid, sid_size(sid));
+ e->expires = jiffies + (id && sid ? IDMAP_TTL : IDMAP_NEG_TTL);
+
+ spin_lock(&idmap_lock);
+ if (id)
+ hash_for_each_possible_safe(idmap_by_id, old, tmp, by_id,
+ id_hash(group, id))
+ if (old->group == group &&
+ !memcmp(&old->id, id, sizeof(*id)))
+ idmap_unlink(old);
+ if (sid)
+ hash_for_each_possible_safe(idmap_by_sid, old, tmp, by_sid,
+ sid_hash(sid))
+ if (sid_eq(&old->sid, sid))
+ idmap_unlink(old);
+ while (idmap_count >= IDMAP_MAX)
+ idmap_unlink(list_last_entry(&idmap_lru, struct idmap_entry,
+ lru));
+ if (id)
+ hash_add(idmap_by_id, &e->by_id, id_hash(group, id));
+ if (sid)
+ hash_add(idmap_by_sid, &e->by_sid, sid_hash(sid));
+ list_add(&e->lru, &idmap_lru);
+ idmap_count++;
+ spin_unlock(&idmap_lock);
+}
+
+/* the SID of a response: well formed and one of a domain's accounts */
+static bool resp_sid(const struct ksmbd_sid_map_response *resp,
+ struct smb_sid *sid)
+{
+ const struct smb_sid *s = (const struct smb_sid *)resp->sid;
+
+ if (s->num_subauth > SID_MAX_SUB_AUTHORITIES ||
+ !ksmbd_idmap_sid_mappable(s))
+ return false;
+ memset(sid, 0, sizeof(*sid));
+ memcpy(sid, s, sid_size(s));
+ return true;
+}
+
+int ksmbd_idmap_id_to_sid(bool group, const struct __kernel_uid_r *rid,
+ struct smb_sid *sid)
+{
+ struct ksmbd_sid_map_response *resp;
+ struct __kernel_uid_r id, rsp_id;
+ struct idmap_entry c;
+ struct smb_sid s;
+ int rc = -EAGAIN;
+
+ if (!ksmbd_idmap_enabled())
+ return -ENOENT;
+ id_norm(&id, rid);
+ if (idmap_find_id(group, &id, &c)) {
+ if (!c.has_sid)
+ return -ENOENT;
+ memcpy(sid, &c.sid, sizeof(*sid));
+ return 0;
+ }
+
+ resp = ksmbd_ipc_sid_map_request(KSMBD_SID_MAP_TO_SID |
+ (group ? KSMBD_SID_MAP_GROUP : 0),
+ &id, NULL, 0);
+ if (!resp)
+ return -EAGAIN;
+ id_norm(&rsp_id, &resp->id);
+ if (resp->status == KSMBD_SID_MAP_NONE) {
+ idmap_add(group, &id, NULL);
+ rc = -ENOENT;
+ } else if (resp->status == KSMBD_SID_MAP_OK &&
+ !!(resp->flags & KSMBD_SID_MAP_GROUP) == group &&
+ !memcmp(&rsp_id, &id, sizeof(id)) && resp_sid(resp, &s)) {
+ idmap_add(group, &id, &s);
+ memcpy(sid, &s, sizeof(*sid));
+ rc = 0;
+ } else if (resp->status == KSMBD_SID_MAP_OK) {
+ pr_err_ratelimited("bad SID map response for an id\n");
+ }
+ kvfree(resp);
+ return rc;
+}
+
+int ksmbd_idmap_sid_to_id(const struct smb_sid *sid, bool *group,
+ struct __kernel_uid_r *id)
+{
+ struct ksmbd_sid_map_response *resp;
+ struct idmap_entry c;
+ struct smb_sid s;
+ int rc = -EAGAIN;
+
+ if (!ksmbd_idmap_enabled() || !ksmbd_idmap_sid_mappable(sid))
+ return -ENOENT;
+ memset(&s, 0, sizeof(s));
+ memcpy(&s, sid, sid_size(sid));
+ if (idmap_find_sid(&s, &c)) {
+ if (!c.has_id)
+ return -ENOENT;
+ *group = c.group;
+ *id = c.id;
+ return 0;
+ }
+
+ resp = ksmbd_ipc_sid_map_request(0, NULL, &s, sid_size(&s));
+ if (!resp)
+ return -EAGAIN;
+ if (resp->status == KSMBD_SID_MAP_NONE) {
+ idmap_add(false, NULL, &s);
+ rc = -ENOENT;
+ } else if (resp->status == KSMBD_SID_MAP_OK &&
+ (resp->id.type == UID_R_LEGACY ||
+ resp->id.type == UID_R_UUID ||
+ resp->id.type == UID_R_GUID)) {
+ *group = resp->flags & KSMBD_SID_MAP_GROUP;
+ id_norm(id, &resp->id);
+ idmap_add(*group, id, &s);
+ rc = 0;
+ } else if (resp->status == KSMBD_SID_MAP_OK) {
+ pr_err_ratelimited("bad SID map response for a SID\n");
+ }
+ kvfree(resp);
+ return rc;
+}
+
+/* a new user space, or ksmbd going away: forget everything */
+void ksmbd_idmap_flush(void)
+{
+ struct idmap_entry *e, *tmp;
+
+ spin_lock(&idmap_lock);
+ list_for_each_entry_safe(e, tmp, &idmap_lru, lru)
+ idmap_unlink(e);
+ spin_unlock(&idmap_lock);
+}
diff --git a/fs/smb/server/idmap.h b/fs/smb/server/idmap.h
new file mode 100644
index 0000000000..47f432c3bb
--- /dev/null
+++ b/fs/smb/server/idmap.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * The Windows SIDs of user and group ids, as user space maps them
+ * (KSMBD_EVENT_SID_MAP_REQUEST), cached.
+ */
+
+#ifndef __KSMBD_IDMAP_H__
+#define __KSMBD_IDMAP_H__
+
+#include <linux/types.h>
+#include <linux/uidgid_r.h>
+
+struct smb_sid;
+
+bool ksmbd_idmap_enabled(void);
+bool ksmbd_idmap_sid_mappable(const struct smb_sid *sid);
+/* 0 and *sid, -ENOENT: no SID of its own, -EAGAIN: user space couldn't say */
+int ksmbd_idmap_id_to_sid(bool group, const struct __kernel_uid_r *id,
+ struct smb_sid *sid);
+/* 0 and *group, *id, -ENOENT: no account's SID, -EAGAIN: as above */
+int ksmbd_idmap_sid_to_id(const struct smb_sid *sid, bool *group,
+ struct __kernel_uid_r *id);
+void ksmbd_idmap_flush(void);
+
+#endif /* __KSMBD_IDMAP_H__ */
diff --git a/fs/smb/server/ksmbd_netlink.h b/fs/smb/server/ksmbd_netlink.h
index 3df5264ad7..c12b4295ed 100644
--- a/fs/smb/server/ksmbd_netlink.h
+++ b/fs/smb/server/ksmbd_netlink.h
@@ -60,6 +60,12 @@
* This event is to make NTLM authentication of a user the login response
* marked KSMBD_USER_FLAG_PASSTHROUGH to be processed in userspace, e.g.
* by a domain controller.
+ *
+ * - KSMBD_EVENT_SID_MAP_REQUEST/RESPONSE(ksmbd_sid_map_request/response)
+ * This event is to translate between the id of a user or group and its
+ * Windows SID in userspace, e.g. with a directory, for the owners and
+ * ACL entries of security descriptors. Sent only to a user space that
+ * set KSMBD_GLOBAL_FLAG_SID_MAP.
*/
#define KSMBD_GENL_NAME "SMBD_GENL"
@@ -86,6 +92,7 @@ struct ksmbd_heartbeat {
#define KSMBD_GLOBAL_FLAG_SMB3_MULTICHANNEL BIT(2)
#define KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION_OFF BIT(3)
#define KSMBD_GLOBAL_FLAG_DURABLE_HANDLE BIT(4)
+#define KSMBD_GLOBAL_FLAG_SID_MAP BIT(5)
/*
* IPC request for ksmbd server startup
@@ -221,6 +228,46 @@ struct ksmbd_ntlm_authen_response {
__u32 reserved[16]; /* Reserved room */
};
+/*
+ * IPC request to translate between a user's or group's id and its SID.
+ *
+ * With KSMBD_SID_MAP_TO_SID, id is the uid (or, with KSMBD_SID_MAP_GROUP,
+ * the gid) whose SID is wanted; otherwise sid is a binary SID (revision,
+ * sub-authority count, 48 bit authority big endian, sub-authorities little
+ * endian) whose id is wanted. The account need not be logged in.
+ */
+#define KSMBD_SID_MAP_TO_SID BIT(0)
+#define KSMBD_SID_MAP_GROUP BIT(1)
+
+#define KSMBD_SID_MAP_SID_SZ 68 /* 8 + 15 sub-authorities */
+
+struct ksmbd_sid_map_request {
+ __u32 handle;
+ __u32 flags; /* KSMBD_SID_MAP_TO_SID, _GROUP */
+ __kernel_uid_r_t id;
+ __u8 sid[KSMBD_SID_MAP_SID_SZ];
+ __u32 reserved[16]; /* Reserved room */
+};
+
+/*
+ * IPC response to a SID map request: the id and the SID of the account,
+ * KSMBD_SID_MAP_GROUP in flags if it is a group. KSMBD_SID_MAP_NONE: the
+ * id has no SID of its own, or the SID belongs to no account (ksmbd may
+ * cache that); KSMBD_SID_MAP_UNAVAILABLE: user space couldn't say now.
+ */
+#define KSMBD_SID_MAP_OK 0
+#define KSMBD_SID_MAP_NONE 1
+#define KSMBD_SID_MAP_UNAVAILABLE 2
+
+struct ksmbd_sid_map_response {
+ __u32 handle;
+ __u32 status; /* KSMBD_SID_MAP_OK, _NONE, ... */
+ __u32 flags; /* KSMBD_SID_MAP_GROUP */
+ __kernel_uid_r_t id;
+ __u8 sid[KSMBD_SID_MAP_SID_SZ];
+ __u32 reserved[16]; /* Reserved room */
+};
+
/*
* IPC request to fetch net share config.
*/
@@ -389,6 +436,9 @@ enum ksmbd_event {
KSMBD_EVENT_NTLM_AUTHEN_REQUEST,
KSMBD_EVENT_NTLM_AUTHEN_RESPONSE,
+ KSMBD_EVENT_SID_MAP_REQUEST = 20,
+ KSMBD_EVENT_SID_MAP_RESPONSE,
+
__KSMBD_EVENT_MAX,
KSMBD_EVENT_MAX = __KSMBD_EVENT_MAX - 1
};
diff --git a/fs/smb/server/mgmt/user_config.c b/fs/smb/server/mgmt/user_config.c
index a25eb0647c..0ff3fc55d0 100644
--- a/fs/smb/server/mgmt/user_config.c
+++ b/fs/smb/server/mgmt/user_config.c
@@ -8,6 +8,7 @@
#include "user_config.h"
#include "../transport_ipc.h"
+#include "../smbacl.h"
struct ksmbd_user *ksmbd_login_user(const char *account, const char *domain)
{
@@ -73,6 +74,8 @@ struct ksmbd_user *ksmbd_alloc_user(struct ksmbd_login_response *resp,
user->ngroups = 0;
user->sgid = NULL;
+ user->nsids = 0;
+ user->sids = NULL;
if (!user->name || !user->passkey)
goto err_free;
@@ -114,6 +117,7 @@ struct ksmbd_user *ksmbd_alloc_user(struct ksmbd_login_response *resp,
ksmbd_debug(SMB, "supplementary groups : %d\n", user->ngroups);
}
+ ksmbd_user_set_token(user);
return user;
err_free:
@@ -127,6 +131,7 @@ struct ksmbd_user *ksmbd_alloc_user(struct ksmbd_login_response *resp,
void ksmbd_free_user(struct ksmbd_user *user)
{
ksmbd_ipc_logout_request(user->name, user->flags);
+ kfree(user->sids);
kfree(user->sgid);
kfree(user->name);
kfree_sensitive(user->passkey);
diff --git a/fs/smb/server/mgmt/user_config.h b/fs/smb/server/mgmt/user_config.h
index 0035675e03..9b6a73580f 100644
--- a/fs/smb/server/mgmt/user_config.h
+++ b/fs/smb/server/mgmt/user_config.h
@@ -8,6 +8,8 @@
#include "../glob.h"
+struct smb_sid;
+
struct ksmbd_user {
unsigned short flags;
@@ -22,6 +24,9 @@ struct ksmbd_user {
char *passkey;
int ngroups;
kgid_t *sgid;
+
+ int nsids; /* ksmbd_user_set_token() */
+ struct smb_sid *sids;
};
static inline bool user_guest(struct ksmbd_user *user)
diff --git a/fs/smb/server/server.c b/fs/smb/server/server.c
index 0827c8c510..c6dc243011 100644
--- a/fs/smb/server/server.c
+++ b/fs/smb/server/server.c
@@ -14,6 +14,7 @@
#include <linux/moduleparam.h>
#include "server.h"
+#include "idmap.h"
#include "smb_common.h"
#include "smb2pdu.h"
#include "../common/smb2status.h"
@@ -746,6 +747,7 @@ static void __exit ksmbd_server_exit(void)
*/
ksmbd_conn_wq_destroy();
ksmbd_release_inode_hash();
+ ksmbd_idmap_flush();
}
MODULE_AUTHOR("Namjae Jeon <linkinjeon@kernel.org>");
diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index db7f677b07..41d2bd732f 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -4606,14 +4606,14 @@ int smb2_open(struct ksmbd_work *work)
if (file_present && !(req->CreateOptions & FILE_DELETE_ON_CLOSE_LE)) {
rc = smb_check_perm_dacl(conn, &path, &daccess,
req->DesiredAccess,
- sess->user->kuid, false);
+ sess->user, false);
if (rc)
goto err_out;
if (maximal_access_ctxt) {
maximal_access = FILE_MAXIMAL_ACCESS_LE;
rc = smb_check_perm_dacl(conn, &path, &maximal_access,
- 0, sess->user->kuid, false);
+ 0, sess->user, false);
if (rc)
goto err_out;
@@ -4799,8 +4799,10 @@ int smb2_open(struct ksmbd_work *work)
ksmbd_debug(SMB, "inherit posix acl failed : %d\n", posix_acl_rc);
rc = smb2_create_sd_buffer(work, req, &path);
- if (rc && rc != -ENOENT)
+ if (rc && rc != -ENOENT) {
+ rsp->hdr.Status = ksmbd_sd_err_status(rc);
goto err_out;
+ }
if (rc == -ENOENT) {
if (test_share_config_flag(work->tcon->share_conf,
@@ -5866,7 +5868,7 @@ static int process_query_dir_entries(struct smb2_query_dir_private *priv)
path.dentry = dent;
rc = smb_check_perm_dacl(priv->work->conn, &path,
&daccess, daccess,
- priv->work->sess->user->kuid,
+ priv->work->sess->user,
true);
if (rc) {
dput(dent);
@@ -8622,6 +8624,7 @@ int smb2_set_info(struct ksmbd_work *work)
le32_to_cpu(req->AdditionalInformation),
(char *)req + le16_to_cpu(req->BufferOffset),
le32_to_cpu(req->BufferLength));
+ rsp->hdr.Status = ksmbd_sd_err_status(rc);
break;
default:
rc = -EOPNOTSUPP;
diff --git a/fs/smb/server/smbacl.c b/fs/smb/server/smbacl.c
index b3daf65798..d6be65e3a9 100644
--- a/fs/smb/server/smbacl.c
+++ b/fs/smb/server/smbacl.c
@@ -16,7 +16,10 @@
#include "smb_common.h"
#include "server.h"
#include "misc.h"
+#include "../common/smb2status.h"
#include "mgmt/share_config.h"
+#include "mgmt/user_config.h"
+#include "idmap.h"
static const struct smb_sid domain = {1, 4, {0, 0, 0, 0, 0, 5},
{cpu_to_le32(21), cpu_to_le32(1), cpu_to_le32(2), cpu_to_le32(3),
@@ -296,8 +299,11 @@ static u32 sid_to_id_r(const struct smb_sid *psid, u8 *id)
return kind;
}
-/* id_to_sid() for any kuid: a classic one gets the usual SIDs */
-void ksmbd_uid_to_sid(kuid_t uid, uint sidtype, struct smb_sid *ssid)
+/*
+ * The SID ksmbd itself gives an id: a classic one the usual SIDs, a UUID
+ * or GUID S-1-22-<kind>-w0-w1-w2-w3.
+ */
+static void native_uid_sid(kuid_t uid, uint sidtype, struct smb_sid *ssid)
{
if (uid_is_legacy(uid) || sidtype == SIDCREATOR_OWNER ||
sidtype == SIDCREATOR_GROUP)
@@ -308,7 +314,7 @@ void ksmbd_uid_to_sid(kuid_t uid, uint sidtype, struct smb_sid *ssid)
id_r_to_sid(SID_UNIX_GUID_USER, uid.guid.b, ssid);
}
-void ksmbd_gid_to_sid(kgid_t gid, uint sidtype, struct smb_sid *ssid)
+static void native_gid_sid(kgid_t gid, uint sidtype, struct smb_sid *ssid)
{
if (gid_is_legacy(gid) || sidtype == SIDCREATOR_OWNER ||
sidtype == SIDCREATOR_GROUP)
@@ -319,6 +325,107 @@ void ksmbd_gid_to_sid(kgid_t gid, uint sidtype, struct smb_sid *ssid)
id_r_to_sid(SID_UNIX_GUID_GROUP, gid.guid.b, ssid);
}
+/* the account's own SID (a directory's objectSid) if user space maps it */
+static int mapped_uid_sid(kuid_t uid, struct smb_sid *ssid)
+{
+ struct __kernel_uid_r id;
+
+ if (uid_eq(uid, GLOBAL_ROOT_UID) || !from_kuid_r(&init_user_ns, uid, &id))
+ return -ENOENT;
+ return ksmbd_idmap_id_to_sid(false, &id, ssid);
+}
+
+static int mapped_gid_sid(kgid_t gid, struct smb_sid *ssid)
+{
+ struct __kernel_uid_r id;
+
+ if (gid_eq(gid, GLOBAL_ROOT_GID) || !from_kgid_r(&init_user_ns, gid, &id))
+ return -ENOENT;
+ return ksmbd_idmap_id_to_sid(true, &id, ssid);
+}
+
+/*
+ * The SID of an owner, a group or an ACL entry: the account's own SID if it
+ * has one (KSMBD_GLOBAL_FLAG_SID_MAP), else ksmbd's. A mapping user space
+ * can't give now leaves ksmbd's SID: showing a descriptor shouldn't fail.
+ */
+void ksmbd_uid_to_sid(kuid_t uid, uint sidtype, struct smb_sid *ssid)
+{
+ if ((sidtype == SIDOWNER || sidtype == SIDUNIX_USER) &&
+ !mapped_uid_sid(uid, ssid))
+ return;
+ native_uid_sid(uid, sidtype, ssid);
+}
+
+void ksmbd_gid_to_sid(kgid_t gid, uint sidtype, struct smb_sid *ssid)
+{
+ if (sidtype == SIDUNIX_GROUP && !mapped_gid_sid(gid, ssid))
+ return;
+ native_gid_sid(gid, sidtype, ssid);
+}
+
+/* the same SID: compare_sids() also takes a prefix */
+static bool sid_equal(const struct smb_sid *a, const struct smb_sid *b)
+{
+ return a->num_subauth == b->num_subauth && !compare_sids(a, b);
+}
+
+/*
+ * The SIDs a user's ACL entries may name, like a Windows access token: the
+ * user's and its groups', each the account's own SID (if user space maps
+ * one) and ksmbd's. Built at login; a
+ * mapping user space couldn't give then is missing for the session (its
+ * ACL entries don't match: access is denied, not granted).
+ */
+void ksmbd_user_set_token(struct ksmbd_user *user)
+{
+ int i, n = 0, max = 2 + 2 * (user->ngroups + 1);
+ struct smb_sid *sids;
+
+ sids = kcalloc(max, sizeof(*sids), KSMBD_DEFAULT_GFP);
+ if (!sids)
+ return;
+ if (!mapped_uid_sid(user->kuid, &sids[n]))
+ n++;
+ native_uid_sid(user->kuid, SIDOWNER, &sids[n++]);
+ for (i = -1; i < user->ngroups; i++) {
+ kgid_t gid = i < 0 ? user->kgid : user->sgid[i];
+
+ if (!mapped_gid_sid(gid, &sids[n]))
+ n++;
+ native_gid_sid(gid, SIDUNIX_GROUP, &sids[n++]);
+ }
+ user->sids = sids;
+ user->nsids = n;
+}
+
+/* whether an ACE's SID names the user (sid, without a token) */
+static bool sid_names_user(const struct ksmbd_user *user,
+ const struct smb_sid *sid, const struct smb_sid *ace)
+{
+ int i;
+
+ if (sid_equal(sid, ace))
+ return true;
+ for (i = 0; i < user->nsids; i++)
+ if (sid_equal(&user->sids[i], ace))
+ return true;
+ return false;
+}
+
+__le32 ksmbd_sd_err_status(int rc)
+{
+ switch (rc) {
+ case -KSMBD_SD_EOWNER:
+ return STATUS_INVALID_OWNER;
+ case -KSMBD_SD_EGROUP:
+ return STATUS_INVALID_PRIMARY_GROUP;
+ case -KSMBD_SD_EUNAVAIL:
+ return STATUS_NO_LOGON_SERVERS;
+ }
+ return 0;
+}
+
static int sid_to_id(struct mnt_idmap *idmap,
struct smb_sid *psid, uint sidtype,
struct smb_fattr *fattr)
@@ -377,6 +484,37 @@ static int sid_to_id(struct mnt_idmap *idmap,
return -EINVAL;
}
+ /* a domain account's own SID: the id user space maps it to */
+ {
+ struct __kernel_uid_r rid;
+ bool group;
+
+ rc = ksmbd_idmap_sid_to_id(psid, &group, &rid);
+ if (rc == -EAGAIN)
+ return -EAGAIN;
+ if (!rc && group != (sidtype != SIDOWNER))
+ return -EINVAL; /* a group's SID as owner, or so */
+ if (!rc && !group) {
+ kuid_t uid = make_kuid_r(&init_user_ns, &rid);
+
+ uid = from_vfsuid(idmap, &init_user_ns, VFSUIDT_INIT(uid));
+ if (!uid_valid(uid))
+ return -EINVAL;
+ fattr->cf_uid = uid;
+ return 0;
+ }
+ if (!rc) {
+ kgid_t gid = make_kgid_r(&init_user_ns, &rid);
+
+ gid = from_vfsgid(idmap, &init_user_ns, VFSGIDT_INIT(gid));
+ if (!gid_valid(gid))
+ return -EINVAL;
+ fattr->cf_gid = gid;
+ return 0;
+ }
+ rc = -EINVAL;
+ }
+
if (sidtype == SIDOWNER) {
kuid_t uid;
uid_t id;
@@ -624,10 +762,28 @@ static int parse_dacl(struct mnt_idmap *idmap,
acl_mode = access_flags_to_mode(fattr, ppace[i]->access_req,
ppace[i]->type);
temp_fattr.cf_uid = INVALID_UID;
+ temp_fattr.cf_gid = INVALID_GID;
ret = sid_to_id(idmap, &ppace[i]->sid, SIDOWNER, &temp_fattr);
- if (ret || uid_eq(temp_fattr.cf_uid, INVALID_UID)) {
- pr_err_ratelimited("%s: Error %d mapping Owner SID to uid\n",
- __func__, ret);
+ if (ret && ret != -EAGAIN)
+ ret = sid_to_id(idmap, &ppace[i]->sid, SIDUNIX_GROUP,
+ &temp_fattr);
+ /* not half the ACL in the inode, all of it in the xattr */
+ if (ret == -EAGAIN)
+ goto out;
+ if (ret) {
+ ksmbd_debug(SMB, "ACE SID has no uid or gid\n");
+ ret = 0;
+ continue;
+ }
+
+ if (!gid_eq(temp_fattr.cf_gid, INVALID_GID)) {
+ struct posix_ace_state_array *g = acl_state.groups;
+ struct posix_ace_state_array *dg = default_acl_state.groups;
+
+ g->aces[g->n].gid = temp_fattr.cf_gid;
+ g->aces[g->n++].perms.allow = (acl_mode & 0700) >> 6;
+ dg->aces[dg->n].gid = temp_fattr.cf_gid;
+ dg->aces[dg->n++].perms.allow = (acl_mode & 0700) >> 6;
continue;
}
@@ -1043,6 +1199,12 @@ int parse_sec_desc(struct mnt_idmap *idmap, struct smb_ntsd *pntsd,
}
rc = sid_to_id(idmap, owner_sid_ptr, SIDOWNER, fattr);
+ if (rc == -EAGAIN)
+ return -KSMBD_SD_EUNAVAIL;
+ /* never "unchanged" for a domain account that has no user */
+ if (rc && ksmbd_idmap_enabled() &&
+ ksmbd_idmap_sid_mappable(owner_sid_ptr))
+ return -KSMBD_SD_EOWNER;
if (rc) {
ksmbd_debug(SMB, "Owner SID has no Unix uid mapping\n");
owner_sid_ptr = NULL;
@@ -1061,6 +1223,11 @@ int parse_sec_desc(struct mnt_idmap *idmap, struct smb_ntsd *pntsd,
return rc;
}
rc = sid_to_id(idmap, group_sid_ptr, SIDUNIX_GROUP, fattr);
+ if (rc == -EAGAIN)
+ return -KSMBD_SD_EUNAVAIL;
+ if (rc && ksmbd_idmap_enabled() &&
+ ksmbd_idmap_sid_mappable(group_sid_ptr))
+ return -KSMBD_SD_EGROUP;
if (rc) {
ksmbd_debug(SMB, "Group SID has no Unix gid mapping\n");
group_sid_ptr = NULL;
@@ -1083,6 +1250,8 @@ int parse_sec_desc(struct mnt_idmap *idmap, struct smb_ntsd *pntsd,
rc = parse_dacl(idmap, dacl_ptr, end_of_acl,
owner_sid_ptr, group_sid_ptr, fattr);
+ if (rc == -EAGAIN)
+ return -KSMBD_SD_EUNAVAIL;
if (rc)
return rc;
}
@@ -1550,9 +1719,10 @@ bool smb_inherit_flags(int flags, bool is_dir)
}
int smb_check_perm_dacl(struct ksmbd_conn *conn, const struct path *path,
- __le32 *pdaccess, __le32 raw_daccess, kuid_t uid,
- bool strict)
+ __le32 *pdaccess, __le32 raw_daccess,
+ struct ksmbd_user *user, bool strict)
{
+ kuid_t uid = user->kuid;
struct mnt_idmap *idmap = mnt_idmap(path->mnt);
struct smb_ntsd *pntsd = NULL;
struct smb_acl *pdacl;
@@ -1634,7 +1804,7 @@ int smb_check_perm_dacl(struct ksmbd_conn *conn, const struct path *path,
}
if (ace->flags & INHERIT_ONLY_ACE ||
- (compare_sids(&sid, &ace->sid) &&
+ (!sid_names_user(user, &sid, &ace->sid) &&
compare_sids(&sid_unix_NFS_mode, &ace->sid) &&
compare_sids(&sid_everyone, &ace->sid) &&
compare_sids(&sid_authusers, &ace->sid) &&
@@ -1683,7 +1853,7 @@ int smb_check_perm_dacl(struct ksmbd_conn *conn, const struct path *path,
sizeof(__le32) * ace->sid.num_subauth)
break;
- if (!compare_sids(&sid, &ace->sid) ||
+ if (sid_names_user(user, &sid, &ace->sid) ||
!compare_sids(&sid_unix_NFS_mode, &ace->sid)) {
found = 1;
break;
diff --git a/fs/smb/server/smbacl.h b/fs/smb/server/smbacl.h
index d4c9b679d8..fdc70e2b6e 100644
--- a/fs/smb/server/smbacl.h
+++ b/fs/smb/server/smbacl.h
@@ -81,6 +81,16 @@ struct posix_acl_state {
struct posix_ace_state_array *groups;
};
+/*
+ * parse_sec_desc() / set_info_sec() errors about the SIDs of domain
+ * accounts (KSMBD_GLOBAL_FLAG_SID_MAP); ksmbd_sd_err_status() names them.
+ */
+#define KSMBD_SD_EOWNER EBADE /* owner SID: no such user */
+#define KSMBD_SD_EGROUP EBADR /* group SID: no such group */
+#define KSMBD_SD_EUNAVAIL EHOSTDOWN /* user space couldn't map now */
+
+__le32 ksmbd_sd_err_status(int rc);
+
int parse_sec_desc(struct mnt_idmap *idmap, struct smb_ntsd *pntsd,
int acl_len, struct smb_fattr *fattr);
int build_sec_desc(struct mnt_idmap *idmap, struct smb_ntsd *pntsd,
@@ -94,9 +104,11 @@ int compare_sids(const struct smb_sid *ctsid, const struct smb_sid *cwsid);
bool smb_inherit_flags(int flags, bool is_dir);
int smb_inherit_dacl(struct ksmbd_conn *conn, const struct path *path,
kuid_t uid, kgid_t gid);
+struct ksmbd_user;
int smb_check_perm_dacl(struct ksmbd_conn *conn, const struct path *path,
- __le32 *pdaccess, __le32 raw_daccess, kuid_t uid,
- bool strict);
+ __le32 *pdaccess, __le32 raw_daccess,
+ struct ksmbd_user *user, bool strict);
+void ksmbd_user_set_token(struct ksmbd_user *user);
int set_info_sec(struct ksmbd_conn *conn, struct ksmbd_tree_connect *tcon,
const struct path *path, struct smb_ntsd *pntsd, int ntsd_len,
bool get_write);
diff --git a/fs/smb/server/transport_ipc.c b/fs/smb/server/transport_ipc.c
index 4d2f16b96e..7f8124333c 100644
--- a/fs/smb/server/transport_ipc.c
+++ b/fs/smb/server/transport_ipc.c
@@ -17,6 +17,7 @@
#include "vfs_cache.h"
#include "transport_ipc.h"
+#include "idmap.h"
#include "server.h"
#include "smb_common.h"
@@ -131,6 +132,10 @@ static const struct nla_policy ksmbd_nl_policy[KSMBD_EVENT_MAX + 1] = {
NLA_POLICY_MIN_LEN(sizeof(struct ksmbd_ntlm_authen_request)),
[KSMBD_EVENT_NTLM_AUTHEN_RESPONSE] =
NLA_POLICY_EXACT_LEN(sizeof(struct ksmbd_ntlm_authen_response)),
+ [KSMBD_EVENT_SID_MAP_REQUEST] =
+ NLA_POLICY_EXACT_LEN(sizeof(struct ksmbd_sid_map_request)),
+ [KSMBD_EVENT_SID_MAP_RESPONSE] =
+ NLA_POLICY_EXACT_LEN(sizeof(struct ksmbd_sid_map_response)),
};
static struct genl_ops ksmbd_genl_ops[] = {
@@ -214,6 +219,14 @@ static struct genl_ops ksmbd_genl_ops[] = {
.cmd = KSMBD_EVENT_NTLM_AUTHEN_RESPONSE,
.doit = handle_generic_event,
},
+ {
+ .cmd = KSMBD_EVENT_SID_MAP_REQUEST,
+ .doit = handle_unsupported_event,
+ },
+ {
+ .cmd = KSMBD_EVENT_SID_MAP_RESPONSE,
+ .doit = handle_generic_event,
+ },
};
static struct genl_family ksmbd_genl_family = {
@@ -327,6 +340,7 @@ static int ipc_server_config_on_startup(struct ksmbd_startup_request *req)
ksmbd_set_fd_limit(req->file_max);
server_conf.flags = req->flags;
+ ksmbd_idmap_flush(); /* a new user space may map otherwise */
server_conf.signing = req->signing;
server_conf.tcp_port = req->tcp_port;
server_conf.ipc_timeout = req->ipc_timeout * HZ;
@@ -567,6 +581,10 @@ static int ipc_validate_msg(struct ipc_msg_table_entry *entry)
if (entry->msg_sz != sizeof(struct ksmbd_ntlm_authen_response))
return -EINVAL;
break;
+ case KSMBD_EVENT_SID_MAP_REQUEST:
+ if (entry->msg_sz != sizeof(struct ksmbd_sid_map_response))
+ return -EINVAL;
+ break;
case KSMBD_EVENT_LOGIN_REQUEST_EXT:
{
struct ksmbd_login_response_ext *resp = entry->response;
@@ -783,6 +801,48 @@ ksmbd_ipc_ntlm_authen_request(const char *challenge, const char *parts[5],
return resp;
}
+/**
+ * ksmbd_ipc_sid_map_request() - have user space translate an id or a SID
+ * @flags: KSMBD_SID_MAP_TO_SID, KSMBD_SID_MAP_GROUP
+ * @id: with KSMBD_SID_MAP_TO_SID, the id
+ * @sid: without it, the binary SID
+ * @sid_len: its length, at most KSMBD_SID_MAP_SID_SZ
+ *
+ * Only for a user space that set KSMBD_GLOBAL_FLAG_SID_MAP.
+ *
+ * Return: the response (kvfree() it), NULL on error or timeout
+ */
+struct ksmbd_sid_map_response *
+ksmbd_ipc_sid_map_request(unsigned int flags, const struct __kernel_uid_r *id,
+ const void *sid, size_t sid_len)
+{
+ struct ksmbd_ipc_msg *msg;
+ struct ksmbd_sid_map_request *req;
+ struct ksmbd_sid_map_response *resp;
+
+ if (!(server_conf.flags & KSMBD_GLOBAL_FLAG_SID_MAP) ||
+ sid_len > KSMBD_SID_MAP_SID_SZ)
+ return NULL;
+
+ msg = ipc_msg_alloc(sizeof(struct ksmbd_sid_map_request));
+ if (!msg)
+ return NULL;
+
+ msg->type = KSMBD_EVENT_SID_MAP_REQUEST;
+ req = (struct ksmbd_sid_map_request *)msg->payload;
+ req->handle = ksmbd_acquire_id(&ipc_ida);
+ req->flags = flags;
+ if (id)
+ req->id = *id;
+ if (sid)
+ memcpy(req->sid, sid, sid_len);
+
+ resp = ipc_msg_send_request(msg, req->handle);
+ ipc_msg_handle_free(req->handle);
+ ipc_msg_free(msg);
+ return resp;
+}
+
struct ksmbd_tree_connect_response *
ksmbd_ipc_tree_connect_request(struct ksmbd_session *sess,
struct ksmbd_share_config *share,
diff --git a/fs/smb/server/transport_ipc.h b/fs/smb/server/transport_ipc.h
index 1aefa23264..390d9fa800 100644
--- a/fs/smb/server/transport_ipc.h
+++ b/fs/smb/server/transport_ipc.h
@@ -32,6 +32,9 @@ struct ksmbd_share_config_response *
ksmbd_ipc_share_config_request(const char *name);
struct ksmbd_spnego_authen_response *
ksmbd_ipc_spnego_authen_request(const char *spnego_blob, int blob_len);
+struct ksmbd_sid_map_response *
+ksmbd_ipc_sid_map_request(unsigned int flags, const struct __kernel_uid_r *id,
+ const void *sid, size_t sid_len);
struct ksmbd_ntlm_authen_response *
ksmbd_ipc_ntlm_authen_request(const char *challenge, const char *parts[5],
const unsigned short lens[5]);
--
2.56.0
^ permalink raw reply [flat|nested] 2+ messages in thread
* [RFC PATCH 4/6] ksmbd: map user and group ids to Windows SIDs through user space
2026-10-28 6:19 [RFC PATCH 0/6] ksmbd: Windows SIDs for user and group ids Jan Koester
@ 2026-10-28 6:20 ` Jan Koester
0 siblings, 0 replies; 2+ messages in thread
From: Jan Koester @ 2026-10-28 6:20 UTC (permalink / raw)
To: Namjae Jeon, Steve French
Cc: Sergey Senozhatsky, Tom Talpey, ChenXiaoSong, Christian Brauner,
linux-cifs, linux-fsdevel, samba-technical, linux-kernel
A domain account has a SID of its own (its objectSid) that Windows
clients use for owners and ACL entries, while files and credentials
carry the account's uid or gid -- a classic id, a UUID or a GUID. ksmbd
shows the ids as S-1-22 SIDs or its server domain SID + uid, which
Windows can't relate to the domain's accounts, and SIDs a client sets
for domain accounts don't map back at all.
Let user space translate in both directions. A user space that sets
KSMBD_GLOBAL_FLAG_SID_MAP at startup gets KSMBD_EVENT_SID_MAP_REQUEST
for the SID of an id ksmbd shows as owner, group or ACL entry, and for
the id of a domain account SID (S-1-5-21-..., outside the server's own
domain) a client sets -- for any account, logged in or not. Answers
are cached: mappings for five minutes, "no mapping" for one minute; an
answer user space couldn't give (its directory unreachable) is never
cached. Ids without a mapping keep the SIDs ksmbd gave them so far.
Showing a descriptor never fails on a missing mapping. Setting one
fails instead of being applied in part: STATUS_NO_LOGON_SERVERS when
user space can't answer, STATUS_INVALID_OWNER or
STATUS_INVALID_PRIMARY_GROUP for a domain SID that maps to no user or
group, which used to be ignored silently. ACEs for groups become
ACL_GROUP entries of the POSIX ACL.
A session matched only its user's own SID against the ACEs of a stored
descriptor. Give the session user the SIDs of its groups too, mapped
and unmapped, like a Windows access token, built at login, and compare
SIDs exactly: compare_sids() accepts a prefix.
Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Jan Koester <jan.koester@tuxist.de>
---
fs/smb/server/Makefile | 2 +-
fs/smb/server/idmap.c | 320 +++++++++++++++++++++++++++++++
fs/smb/server/idmap.h | 25 +++
fs/smb/server/ksmbd_netlink.h | 50 +++++
fs/smb/server/mgmt/user_config.c | 5 +
fs/smb/server/mgmt/user_config.h | 5 +
fs/smb/server/server.c | 2 +
fs/smb/server/smb2pdu.c | 11 +-
fs/smb/server/smbacl.c | 190 +++++++++++++++++-
fs/smb/server/smbacl.h | 16 +-
fs/smb/server/transport_ipc.c | 60 ++++++
fs/smb/server/transport_ipc.h | 3 +
12 files changed, 672 insertions(+), 17 deletions(-)
create mode 100644 fs/smb/server/idmap.c
create mode 100644 fs/smb/server/idmap.h
diff --git a/fs/smb/server/Makefile b/fs/smb/server/Makefile
index a3e9306055..39a6ec4ca9 100644
--- a/fs/smb/server/Makefile
+++ b/fs/smb/server/Makefile
@@ -8,7 +8,7 @@ ksmbd-y := unicode.o auth.o vfs.o vfs_cache.o server.o ndr.o \
misc.o oplock.o connection.o ksmbd_work.o crypto_ctx.o \
mgmt/ksmbd_ida.o mgmt/user_config.o mgmt/share_config.o \
mgmt/tree_connect.o mgmt/user_session.o smb_common.o \
- transport_tcp.o transport_ipc.o smbacl.o smb2pdu.o \
+ transport_tcp.o transport_ipc.o smbacl.o idmap.o smb2pdu.o \
smb2ops.o smb2misc.o ksmbd_spnego_negtokeninit.asn1.o \
ksmbd_spnego_negtokentarg.asn1.o asn1.o compress.o
diff --git a/fs/smb/server/idmap.c b/fs/smb/server/idmap.c
new file mode 100644
index 0000000000..8ea83b3e93
--- /dev/null
+++ b/fs/smb/server/idmap.c
@@ -0,0 +1,320 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * The Windows SIDs of user and group ids, as user space maps them.
+ *
+ * A domain account has a SID of its own (its objectSid) that Windows uses
+ * for owners and ACL entries, while files and credentials carry the
+ * account's uid or gid -- a classic id, a UUID or a GUID. ksmbd asks user
+ * space (KSMBD_EVENT_SID_MAP_REQUEST) for every owner and ACL entry it
+ * shows or sets, also of accounts that aren't logged in, and keeps the
+ * answers here for a while: mappings for IDMAP_TTL, "no such mapping" for
+ * IDMAP_NEG_TTL. An answer that user space couldn't give (its directory
+ * unreachable) is never cached. Only SIDs of the form S-1-5-21-... (a
+ * domain's accounts) outside the server's own domain are looked up.
+ */
+
+#include <linux/hashtable.h>
+#include <linux/jhash.h>
+#include <linux/jiffies.h>
+#include <linux/list.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+#include "glob.h"
+#include "idmap.h"
+#include "ksmbd_netlink.h"
+#include "server.h"
+#include "smbacl.h"
+#include "transport_ipc.h"
+
+#define IDMAP_TTL (300 * HZ)
+#define IDMAP_NEG_TTL (60 * HZ)
+#define IDMAP_MAX 4096
+#define IDMAP_BITS 9
+
+/*
+ * A mapping (id and SID, in both tables) or a negative entry for an id or
+ * a SID (in that one table).
+ */
+struct idmap_entry {
+ struct list_head lru;
+ struct hlist_node by_id;
+ struct hlist_node by_sid;
+ bool has_id;
+ bool has_sid;
+ bool group;
+ struct __kernel_uid_r id;
+ struct smb_sid sid;
+ unsigned long expires;
+};
+
+static DEFINE_HASHTABLE(idmap_by_id, IDMAP_BITS);
+static DEFINE_HASHTABLE(idmap_by_sid, IDMAP_BITS);
+static LIST_HEAD(idmap_lru);
+static unsigned int idmap_count;
+static DEFINE_SPINLOCK(idmap_lock);
+
+static const u8 nt_authority[NUM_AUTHS] = {0, 0, 0, 0, 0, 5};
+
+static size_t sid_size(const struct smb_sid *sid)
+{
+ return CIFS_SID_BASE_SIZE + sizeof(__le32) * sid->num_subauth;
+}
+
+static bool sid_eq(const struct smb_sid *a, const struct smb_sid *b)
+{
+ return a->num_subauth == b->num_subauth && !memcmp(a, b, sid_size(a));
+}
+
+/* only the member type selects, the rest zero: comparable with memcmp() */
+static void id_norm(struct __kernel_uid_r *out, const struct __kernel_uid_r *in)
+{
+ memset(out, 0, sizeof(*out));
+ out->type = in->type;
+ if (in->type == UID_R_LEGACY)
+ out->legacy = in->legacy;
+ else if (in->type == UID_R_UUID || in->type == UID_R_GUID)
+ memcpy(out->uuid, in->uuid, sizeof(out->uuid));
+}
+
+static u32 id_hash(bool group, const struct __kernel_uid_r *id)
+{
+ return jhash(id, sizeof(*id), group);
+}
+
+static u32 sid_hash(const struct smb_sid *sid)
+{
+ return jhash(sid, sid_size(sid), 0);
+}
+
+bool ksmbd_idmap_enabled(void)
+{
+ return server_conf.flags & KSMBD_GLOBAL_FLAG_SID_MAP;
+}
+
+/* S-1-5-21-..., not of the server's own domain */
+bool ksmbd_idmap_sid_mappable(const struct smb_sid *sid)
+{
+ const struct smb_sid *own = &server_conf.domain_sid;
+
+ if (sid->revision != 1 || sid->num_subauth < 2 ||
+ sid->num_subauth > SID_MAX_SUB_AUTHORITIES ||
+ memcmp(sid->authority, nt_authority, NUM_AUTHS) ||
+ le32_to_cpu(sid->sub_auth[0]) != 21)
+ return false;
+ return !(sid->num_subauth == own->num_subauth + 1 &&
+ !memcmp(sid->sub_auth, own->sub_auth,
+ sizeof(__le32) * own->num_subauth));
+}
+
+/* with idmap_lock */
+static void idmap_unlink(struct idmap_entry *e)
+{
+ list_del(&e->lru);
+ if (e->has_id)
+ hash_del(&e->by_id);
+ if (e->has_sid)
+ hash_del(&e->by_sid);
+ idmap_count--;
+ kfree(e);
+}
+
+/* a copy of the cached entry for the id (true), or false */
+static bool idmap_find_id(bool group, const struct __kernel_uid_r *id,
+ struct idmap_entry *out)
+{
+ struct idmap_entry *e;
+ bool found = false;
+
+ spin_lock(&idmap_lock);
+ hash_for_each_possible(idmap_by_id, e, by_id, id_hash(group, id)) {
+ if (e->group != group || memcmp(&e->id, id, sizeof(*id)))
+ continue;
+ if (time_after(jiffies, e->expires)) {
+ idmap_unlink(e);
+ break;
+ }
+ list_move(&e->lru, &idmap_lru);
+ *out = *e;
+ found = true;
+ break;
+ }
+ spin_unlock(&idmap_lock);
+ return found;
+}
+
+static bool idmap_find_sid(const struct smb_sid *sid, struct idmap_entry *out)
+{
+ struct idmap_entry *e;
+ bool found = false;
+
+ spin_lock(&idmap_lock);
+ hash_for_each_possible(idmap_by_sid, e, by_sid, sid_hash(sid)) {
+ if (!sid_eq(&e->sid, sid))
+ continue;
+ if (time_after(jiffies, e->expires)) {
+ idmap_unlink(e);
+ break;
+ }
+ list_move(&e->lru, &idmap_lru);
+ *out = *e;
+ found = true;
+ break;
+ }
+ spin_unlock(&idmap_lock);
+ return found;
+}
+
+/*
+ * Cache a mapping (id and sid), or that id (sid NULL) or sid (id NULL) has
+ * none. It replaces what was cached for the same id or SID.
+ */
+static void idmap_add(bool group, const struct __kernel_uid_r *id,
+ const struct smb_sid *sid)
+{
+ struct idmap_entry *e, *old;
+ struct hlist_node *tmp;
+
+ e = kzalloc_obj(struct idmap_entry, KSMBD_DEFAULT_GFP);
+ if (!e)
+ return;
+ e->group = group;
+ e->has_id = id;
+ e->has_sid = sid;
+ if (id)
+ e->id = *id;
+ if (sid)
+ memcpy(&e->sid, sid, sid_size(sid));
+ e->expires = jiffies + (id && sid ? IDMAP_TTL : IDMAP_NEG_TTL);
+
+ spin_lock(&idmap_lock);
+ if (id)
+ hash_for_each_possible_safe(idmap_by_id, old, tmp, by_id,
+ id_hash(group, id))
+ if (old->group == group &&
+ !memcmp(&old->id, id, sizeof(*id)))
+ idmap_unlink(old);
+ if (sid)
+ hash_for_each_possible_safe(idmap_by_sid, old, tmp, by_sid,
+ sid_hash(sid))
+ if (sid_eq(&old->sid, sid))
+ idmap_unlink(old);
+ while (idmap_count >= IDMAP_MAX)
+ idmap_unlink(list_last_entry(&idmap_lru, struct idmap_entry,
+ lru));
+ if (id)
+ hash_add(idmap_by_id, &e->by_id, id_hash(group, id));
+ if (sid)
+ hash_add(idmap_by_sid, &e->by_sid, sid_hash(sid));
+ list_add(&e->lru, &idmap_lru);
+ idmap_count++;
+ spin_unlock(&idmap_lock);
+}
+
+/* the SID of a response: well formed and one of a domain's accounts */
+static bool resp_sid(const struct ksmbd_sid_map_response *resp,
+ struct smb_sid *sid)
+{
+ const struct smb_sid *s = (const struct smb_sid *)resp->sid;
+
+ if (s->num_subauth > SID_MAX_SUB_AUTHORITIES ||
+ !ksmbd_idmap_sid_mappable(s))
+ return false;
+ memset(sid, 0, sizeof(*sid));
+ memcpy(sid, s, sid_size(s));
+ return true;
+}
+
+int ksmbd_idmap_id_to_sid(bool group, const struct __kernel_uid_r *rid,
+ struct smb_sid *sid)
+{
+ struct ksmbd_sid_map_response *resp;
+ struct __kernel_uid_r id, rsp_id;
+ struct idmap_entry c;
+ struct smb_sid s;
+ int rc = -EAGAIN;
+
+ if (!ksmbd_idmap_enabled())
+ return -ENOENT;
+ id_norm(&id, rid);
+ if (idmap_find_id(group, &id, &c)) {
+ if (!c.has_sid)
+ return -ENOENT;
+ memcpy(sid, &c.sid, sizeof(*sid));
+ return 0;
+ }
+
+ resp = ksmbd_ipc_sid_map_request(KSMBD_SID_MAP_TO_SID |
+ (group ? KSMBD_SID_MAP_GROUP : 0),
+ &id, NULL, 0);
+ if (!resp)
+ return -EAGAIN;
+ id_norm(&rsp_id, &resp->id);
+ if (resp->status == KSMBD_SID_MAP_NONE) {
+ idmap_add(group, &id, NULL);
+ rc = -ENOENT;
+ } else if (resp->status == KSMBD_SID_MAP_OK &&
+ !!(resp->flags & KSMBD_SID_MAP_GROUP) == group &&
+ !memcmp(&rsp_id, &id, sizeof(id)) && resp_sid(resp, &s)) {
+ idmap_add(group, &id, &s);
+ memcpy(sid, &s, sizeof(*sid));
+ rc = 0;
+ } else if (resp->status == KSMBD_SID_MAP_OK) {
+ pr_err_ratelimited("bad SID map response for an id\n");
+ }
+ kvfree(resp);
+ return rc;
+}
+
+int ksmbd_idmap_sid_to_id(const struct smb_sid *sid, bool *group,
+ struct __kernel_uid_r *id)
+{
+ struct ksmbd_sid_map_response *resp;
+ struct idmap_entry c;
+ struct smb_sid s;
+ int rc = -EAGAIN;
+
+ if (!ksmbd_idmap_enabled() || !ksmbd_idmap_sid_mappable(sid))
+ return -ENOENT;
+ memset(&s, 0, sizeof(s));
+ memcpy(&s, sid, sid_size(sid));
+ if (idmap_find_sid(&s, &c)) {
+ if (!c.has_id)
+ return -ENOENT;
+ *group = c.group;
+ *id = c.id;
+ return 0;
+ }
+
+ resp = ksmbd_ipc_sid_map_request(0, NULL, &s, sid_size(&s));
+ if (!resp)
+ return -EAGAIN;
+ if (resp->status == KSMBD_SID_MAP_NONE) {
+ idmap_add(false, NULL, &s);
+ rc = -ENOENT;
+ } else if (resp->status == KSMBD_SID_MAP_OK &&
+ (resp->id.type == UID_R_LEGACY ||
+ resp->id.type == UID_R_UUID ||
+ resp->id.type == UID_R_GUID)) {
+ *group = resp->flags & KSMBD_SID_MAP_GROUP;
+ id_norm(id, &resp->id);
+ idmap_add(*group, id, &s);
+ rc = 0;
+ } else if (resp->status == KSMBD_SID_MAP_OK) {
+ pr_err_ratelimited("bad SID map response for a SID\n");
+ }
+ kvfree(resp);
+ return rc;
+}
+
+/* a new user space, or ksmbd going away: forget everything */
+void ksmbd_idmap_flush(void)
+{
+ struct idmap_entry *e, *tmp;
+
+ spin_lock(&idmap_lock);
+ list_for_each_entry_safe(e, tmp, &idmap_lru, lru)
+ idmap_unlink(e);
+ spin_unlock(&idmap_lock);
+}
diff --git a/fs/smb/server/idmap.h b/fs/smb/server/idmap.h
new file mode 100644
index 0000000000..47f432c3bb
--- /dev/null
+++ b/fs/smb/server/idmap.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * The Windows SIDs of user and group ids, as user space maps them
+ * (KSMBD_EVENT_SID_MAP_REQUEST), cached.
+ */
+
+#ifndef __KSMBD_IDMAP_H__
+#define __KSMBD_IDMAP_H__
+
+#include <linux/types.h>
+#include <linux/uidgid_r.h>
+
+struct smb_sid;
+
+bool ksmbd_idmap_enabled(void);
+bool ksmbd_idmap_sid_mappable(const struct smb_sid *sid);
+/* 0 and *sid, -ENOENT: no SID of its own, -EAGAIN: user space couldn't say */
+int ksmbd_idmap_id_to_sid(bool group, const struct __kernel_uid_r *id,
+ struct smb_sid *sid);
+/* 0 and *group, *id, -ENOENT: no account's SID, -EAGAIN: as above */
+int ksmbd_idmap_sid_to_id(const struct smb_sid *sid, bool *group,
+ struct __kernel_uid_r *id);
+void ksmbd_idmap_flush(void);
+
+#endif /* __KSMBD_IDMAP_H__ */
diff --git a/fs/smb/server/ksmbd_netlink.h b/fs/smb/server/ksmbd_netlink.h
index 3df5264ad7..c12b4295ed 100644
--- a/fs/smb/server/ksmbd_netlink.h
+++ b/fs/smb/server/ksmbd_netlink.h
@@ -60,6 +60,12 @@
* This event is to make NTLM authentication of a user the login response
* marked KSMBD_USER_FLAG_PASSTHROUGH to be processed in userspace, e.g.
* by a domain controller.
+ *
+ * - KSMBD_EVENT_SID_MAP_REQUEST/RESPONSE(ksmbd_sid_map_request/response)
+ * This event is to translate between the id of a user or group and its
+ * Windows SID in userspace, e.g. with a directory, for the owners and
+ * ACL entries of security descriptors. Sent only to a user space that
+ * set KSMBD_GLOBAL_FLAG_SID_MAP.
*/
#define KSMBD_GENL_NAME "SMBD_GENL"
@@ -86,6 +92,7 @@ struct ksmbd_heartbeat {
#define KSMBD_GLOBAL_FLAG_SMB3_MULTICHANNEL BIT(2)
#define KSMBD_GLOBAL_FLAG_SMB2_ENCRYPTION_OFF BIT(3)
#define KSMBD_GLOBAL_FLAG_DURABLE_HANDLE BIT(4)
+#define KSMBD_GLOBAL_FLAG_SID_MAP BIT(5)
/*
* IPC request for ksmbd server startup
@@ -221,6 +228,46 @@ struct ksmbd_ntlm_authen_response {
__u32 reserved[16]; /* Reserved room */
};
+/*
+ * IPC request to translate between a user's or group's id and its SID.
+ *
+ * With KSMBD_SID_MAP_TO_SID, id is the uid (or, with KSMBD_SID_MAP_GROUP,
+ * the gid) whose SID is wanted; otherwise sid is a binary SID (revision,
+ * sub-authority count, 48 bit authority big endian, sub-authorities little
+ * endian) whose id is wanted. The account need not be logged in.
+ */
+#define KSMBD_SID_MAP_TO_SID BIT(0)
+#define KSMBD_SID_MAP_GROUP BIT(1)
+
+#define KSMBD_SID_MAP_SID_SZ 68 /* 8 + 15 sub-authorities */
+
+struct ksmbd_sid_map_request {
+ __u32 handle;
+ __u32 flags; /* KSMBD_SID_MAP_TO_SID, _GROUP */
+ __kernel_uid_r_t id;
+ __u8 sid[KSMBD_SID_MAP_SID_SZ];
+ __u32 reserved[16]; /* Reserved room */
+};
+
+/*
+ * IPC response to a SID map request: the id and the SID of the account,
+ * KSMBD_SID_MAP_GROUP in flags if it is a group. KSMBD_SID_MAP_NONE: the
+ * id has no SID of its own, or the SID belongs to no account (ksmbd may
+ * cache that); KSMBD_SID_MAP_UNAVAILABLE: user space couldn't say now.
+ */
+#define KSMBD_SID_MAP_OK 0
+#define KSMBD_SID_MAP_NONE 1
+#define KSMBD_SID_MAP_UNAVAILABLE 2
+
+struct ksmbd_sid_map_response {
+ __u32 handle;
+ __u32 status; /* KSMBD_SID_MAP_OK, _NONE, ... */
+ __u32 flags; /* KSMBD_SID_MAP_GROUP */
+ __kernel_uid_r_t id;
+ __u8 sid[KSMBD_SID_MAP_SID_SZ];
+ __u32 reserved[16]; /* Reserved room */
+};
+
/*
* IPC request to fetch net share config.
*/
@@ -389,6 +436,9 @@ enum ksmbd_event {
KSMBD_EVENT_NTLM_AUTHEN_REQUEST,
KSMBD_EVENT_NTLM_AUTHEN_RESPONSE,
+ KSMBD_EVENT_SID_MAP_REQUEST = 20,
+ KSMBD_EVENT_SID_MAP_RESPONSE,
+
__KSMBD_EVENT_MAX,
KSMBD_EVENT_MAX = __KSMBD_EVENT_MAX - 1
};
diff --git a/fs/smb/server/mgmt/user_config.c b/fs/smb/server/mgmt/user_config.c
index a25eb0647c..0ff3fc55d0 100644
--- a/fs/smb/server/mgmt/user_config.c
+++ b/fs/smb/server/mgmt/user_config.c
@@ -8,6 +8,7 @@
#include "user_config.h"
#include "../transport_ipc.h"
+#include "../smbacl.h"
struct ksmbd_user *ksmbd_login_user(const char *account, const char *domain)
{
@@ -73,6 +74,8 @@ struct ksmbd_user *ksmbd_alloc_user(struct ksmbd_login_response *resp,
user->ngroups = 0;
user->sgid = NULL;
+ user->nsids = 0;
+ user->sids = NULL;
if (!user->name || !user->passkey)
goto err_free;
@@ -114,6 +117,7 @@ struct ksmbd_user *ksmbd_alloc_user(struct ksmbd_login_response *resp,
ksmbd_debug(SMB, "supplementary groups : %d\n", user->ngroups);
}
+ ksmbd_user_set_token(user);
return user;
err_free:
@@ -127,6 +131,7 @@ struct ksmbd_user *ksmbd_alloc_user(struct ksmbd_login_response *resp,
void ksmbd_free_user(struct ksmbd_user *user)
{
ksmbd_ipc_logout_request(user->name, user->flags);
+ kfree(user->sids);
kfree(user->sgid);
kfree(user->name);
kfree_sensitive(user->passkey);
diff --git a/fs/smb/server/mgmt/user_config.h b/fs/smb/server/mgmt/user_config.h
index 0035675e03..9b6a73580f 100644
--- a/fs/smb/server/mgmt/user_config.h
+++ b/fs/smb/server/mgmt/user_config.h
@@ -8,6 +8,8 @@
#include "../glob.h"
+struct smb_sid;
+
struct ksmbd_user {
unsigned short flags;
@@ -22,6 +24,9 @@ struct ksmbd_user {
char *passkey;
int ngroups;
kgid_t *sgid;
+
+ int nsids; /* ksmbd_user_set_token() */
+ struct smb_sid *sids;
};
static inline bool user_guest(struct ksmbd_user *user)
diff --git a/fs/smb/server/server.c b/fs/smb/server/server.c
index 0827c8c510..c6dc243011 100644
--- a/fs/smb/server/server.c
+++ b/fs/smb/server/server.c
@@ -14,6 +14,7 @@
#include <linux/moduleparam.h>
#include "server.h"
+#include "idmap.h"
#include "smb_common.h"
#include "smb2pdu.h"
#include "../common/smb2status.h"
@@ -746,6 +747,7 @@ static void __exit ksmbd_server_exit(void)
*/
ksmbd_conn_wq_destroy();
ksmbd_release_inode_hash();
+ ksmbd_idmap_flush();
}
MODULE_AUTHOR("Namjae Jeon <linkinjeon@kernel.org>");
diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index db7f677b07..41d2bd732f 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -4606,14 +4606,14 @@ int smb2_open(struct ksmbd_work *work)
if (file_present && !(req->CreateOptions & FILE_DELETE_ON_CLOSE_LE)) {
rc = smb_check_perm_dacl(conn, &path, &daccess,
req->DesiredAccess,
- sess->user->kuid, false);
+ sess->user, false);
if (rc)
goto err_out;
if (maximal_access_ctxt) {
maximal_access = FILE_MAXIMAL_ACCESS_LE;
rc = smb_check_perm_dacl(conn, &path, &maximal_access,
- 0, sess->user->kuid, false);
+ 0, sess->user, false);
if (rc)
goto err_out;
@@ -4799,8 +4799,10 @@ int smb2_open(struct ksmbd_work *work)
ksmbd_debug(SMB, "inherit posix acl failed : %d\n", posix_acl_rc);
rc = smb2_create_sd_buffer(work, req, &path);
- if (rc && rc != -ENOENT)
+ if (rc && rc != -ENOENT) {
+ rsp->hdr.Status = ksmbd_sd_err_status(rc);
goto err_out;
+ }
if (rc == -ENOENT) {
if (test_share_config_flag(work->tcon->share_conf,
@@ -5866,7 +5868,7 @@ static int process_query_dir_entries(struct smb2_query_dir_private *priv)
path.dentry = dent;
rc = smb_check_perm_dacl(priv->work->conn, &path,
&daccess, daccess,
- priv->work->sess->user->kuid,
+ priv->work->sess->user,
true);
if (rc) {
dput(dent);
@@ -8622,6 +8624,7 @@ int smb2_set_info(struct ksmbd_work *work)
le32_to_cpu(req->AdditionalInformation),
(char *)req + le16_to_cpu(req->BufferOffset),
le32_to_cpu(req->BufferLength));
+ rsp->hdr.Status = ksmbd_sd_err_status(rc);
break;
default:
rc = -EOPNOTSUPP;
diff --git a/fs/smb/server/smbacl.c b/fs/smb/server/smbacl.c
index b3daf65798..d6be65e3a9 100644
--- a/fs/smb/server/smbacl.c
+++ b/fs/smb/server/smbacl.c
@@ -16,7 +16,10 @@
#include "smb_common.h"
#include "server.h"
#include "misc.h"
+#include "../common/smb2status.h"
#include "mgmt/share_config.h"
+#include "mgmt/user_config.h"
+#include "idmap.h"
static const struct smb_sid domain = {1, 4, {0, 0, 0, 0, 0, 5},
{cpu_to_le32(21), cpu_to_le32(1), cpu_to_le32(2), cpu_to_le32(3),
@@ -296,8 +299,11 @@ static u32 sid_to_id_r(const struct smb_sid *psid, u8 *id)
return kind;
}
-/* id_to_sid() for any kuid: a classic one gets the usual SIDs */
-void ksmbd_uid_to_sid(kuid_t uid, uint sidtype, struct smb_sid *ssid)
+/*
+ * The SID ksmbd itself gives an id: a classic one the usual SIDs, a UUID
+ * or GUID S-1-22-<kind>-w0-w1-w2-w3.
+ */
+static void native_uid_sid(kuid_t uid, uint sidtype, struct smb_sid *ssid)
{
if (uid_is_legacy(uid) || sidtype == SIDCREATOR_OWNER ||
sidtype == SIDCREATOR_GROUP)
@@ -308,7 +314,7 @@ void ksmbd_uid_to_sid(kuid_t uid, uint sidtype, struct smb_sid *ssid)
id_r_to_sid(SID_UNIX_GUID_USER, uid.guid.b, ssid);
}
-void ksmbd_gid_to_sid(kgid_t gid, uint sidtype, struct smb_sid *ssid)
+static void native_gid_sid(kgid_t gid, uint sidtype, struct smb_sid *ssid)
{
if (gid_is_legacy(gid) || sidtype == SIDCREATOR_OWNER ||
sidtype == SIDCREATOR_GROUP)
@@ -319,6 +325,107 @@ void ksmbd_gid_to_sid(kgid_t gid, uint sidtype, struct smb_sid *ssid)
id_r_to_sid(SID_UNIX_GUID_GROUP, gid.guid.b, ssid);
}
+/* the account's own SID (a directory's objectSid) if user space maps it */
+static int mapped_uid_sid(kuid_t uid, struct smb_sid *ssid)
+{
+ struct __kernel_uid_r id;
+
+ if (uid_eq(uid, GLOBAL_ROOT_UID) || !from_kuid_r(&init_user_ns, uid, &id))
+ return -ENOENT;
+ return ksmbd_idmap_id_to_sid(false, &id, ssid);
+}
+
+static int mapped_gid_sid(kgid_t gid, struct smb_sid *ssid)
+{
+ struct __kernel_uid_r id;
+
+ if (gid_eq(gid, GLOBAL_ROOT_GID) || !from_kgid_r(&init_user_ns, gid, &id))
+ return -ENOENT;
+ return ksmbd_idmap_id_to_sid(true, &id, ssid);
+}
+
+/*
+ * The SID of an owner, a group or an ACL entry: the account's own SID if it
+ * has one (KSMBD_GLOBAL_FLAG_SID_MAP), else ksmbd's. A mapping user space
+ * can't give now leaves ksmbd's SID: showing a descriptor shouldn't fail.
+ */
+void ksmbd_uid_to_sid(kuid_t uid, uint sidtype, struct smb_sid *ssid)
+{
+ if ((sidtype == SIDOWNER || sidtype == SIDUNIX_USER) &&
+ !mapped_uid_sid(uid, ssid))
+ return;
+ native_uid_sid(uid, sidtype, ssid);
+}
+
+void ksmbd_gid_to_sid(kgid_t gid, uint sidtype, struct smb_sid *ssid)
+{
+ if (sidtype == SIDUNIX_GROUP && !mapped_gid_sid(gid, ssid))
+ return;
+ native_gid_sid(gid, sidtype, ssid);
+}
+
+/* the same SID: compare_sids() also takes a prefix */
+static bool sid_equal(const struct smb_sid *a, const struct smb_sid *b)
+{
+ return a->num_subauth == b->num_subauth && !compare_sids(a, b);
+}
+
+/*
+ * The SIDs a user's ACL entries may name, like a Windows access token: the
+ * user's and its groups', each the account's own SID (if user space maps
+ * one) and ksmbd's. Built at login; a
+ * mapping user space couldn't give then is missing for the session (its
+ * ACL entries don't match: access is denied, not granted).
+ */
+void ksmbd_user_set_token(struct ksmbd_user *user)
+{
+ int i, n = 0, max = 2 + 2 * (user->ngroups + 1);
+ struct smb_sid *sids;
+
+ sids = kcalloc(max, sizeof(*sids), KSMBD_DEFAULT_GFP);
+ if (!sids)
+ return;
+ if (!mapped_uid_sid(user->kuid, &sids[n]))
+ n++;
+ native_uid_sid(user->kuid, SIDOWNER, &sids[n++]);
+ for (i = -1; i < user->ngroups; i++) {
+ kgid_t gid = i < 0 ? user->kgid : user->sgid[i];
+
+ if (!mapped_gid_sid(gid, &sids[n]))
+ n++;
+ native_gid_sid(gid, SIDUNIX_GROUP, &sids[n++]);
+ }
+ user->sids = sids;
+ user->nsids = n;
+}
+
+/* whether an ACE's SID names the user (sid, without a token) */
+static bool sid_names_user(const struct ksmbd_user *user,
+ const struct smb_sid *sid, const struct smb_sid *ace)
+{
+ int i;
+
+ if (sid_equal(sid, ace))
+ return true;
+ for (i = 0; i < user->nsids; i++)
+ if (sid_equal(&user->sids[i], ace))
+ return true;
+ return false;
+}
+
+__le32 ksmbd_sd_err_status(int rc)
+{
+ switch (rc) {
+ case -KSMBD_SD_EOWNER:
+ return STATUS_INVALID_OWNER;
+ case -KSMBD_SD_EGROUP:
+ return STATUS_INVALID_PRIMARY_GROUP;
+ case -KSMBD_SD_EUNAVAIL:
+ return STATUS_NO_LOGON_SERVERS;
+ }
+ return 0;
+}
+
static int sid_to_id(struct mnt_idmap *idmap,
struct smb_sid *psid, uint sidtype,
struct smb_fattr *fattr)
@@ -377,6 +484,37 @@ static int sid_to_id(struct mnt_idmap *idmap,
return -EINVAL;
}
+ /* a domain account's own SID: the id user space maps it to */
+ {
+ struct __kernel_uid_r rid;
+ bool group;
+
+ rc = ksmbd_idmap_sid_to_id(psid, &group, &rid);
+ if (rc == -EAGAIN)
+ return -EAGAIN;
+ if (!rc && group != (sidtype != SIDOWNER))
+ return -EINVAL; /* a group's SID as owner, or so */
+ if (!rc && !group) {
+ kuid_t uid = make_kuid_r(&init_user_ns, &rid);
+
+ uid = from_vfsuid(idmap, &init_user_ns, VFSUIDT_INIT(uid));
+ if (!uid_valid(uid))
+ return -EINVAL;
+ fattr->cf_uid = uid;
+ return 0;
+ }
+ if (!rc) {
+ kgid_t gid = make_kgid_r(&init_user_ns, &rid);
+
+ gid = from_vfsgid(idmap, &init_user_ns, VFSGIDT_INIT(gid));
+ if (!gid_valid(gid))
+ return -EINVAL;
+ fattr->cf_gid = gid;
+ return 0;
+ }
+ rc = -EINVAL;
+ }
+
if (sidtype == SIDOWNER) {
kuid_t uid;
uid_t id;
@@ -624,10 +762,28 @@ static int parse_dacl(struct mnt_idmap *idmap,
acl_mode = access_flags_to_mode(fattr, ppace[i]->access_req,
ppace[i]->type);
temp_fattr.cf_uid = INVALID_UID;
+ temp_fattr.cf_gid = INVALID_GID;
ret = sid_to_id(idmap, &ppace[i]->sid, SIDOWNER, &temp_fattr);
- if (ret || uid_eq(temp_fattr.cf_uid, INVALID_UID)) {
- pr_err_ratelimited("%s: Error %d mapping Owner SID to uid\n",
- __func__, ret);
+ if (ret && ret != -EAGAIN)
+ ret = sid_to_id(idmap, &ppace[i]->sid, SIDUNIX_GROUP,
+ &temp_fattr);
+ /* not half the ACL in the inode, all of it in the xattr */
+ if (ret == -EAGAIN)
+ goto out;
+ if (ret) {
+ ksmbd_debug(SMB, "ACE SID has no uid or gid\n");
+ ret = 0;
+ continue;
+ }
+
+ if (!gid_eq(temp_fattr.cf_gid, INVALID_GID)) {
+ struct posix_ace_state_array *g = acl_state.groups;
+ struct posix_ace_state_array *dg = default_acl_state.groups;
+
+ g->aces[g->n].gid = temp_fattr.cf_gid;
+ g->aces[g->n++].perms.allow = (acl_mode & 0700) >> 6;
+ dg->aces[dg->n].gid = temp_fattr.cf_gid;
+ dg->aces[dg->n++].perms.allow = (acl_mode & 0700) >> 6;
continue;
}
@@ -1043,6 +1199,12 @@ int parse_sec_desc(struct mnt_idmap *idmap, struct smb_ntsd *pntsd,
}
rc = sid_to_id(idmap, owner_sid_ptr, SIDOWNER, fattr);
+ if (rc == -EAGAIN)
+ return -KSMBD_SD_EUNAVAIL;
+ /* never "unchanged" for a domain account that has no user */
+ if (rc && ksmbd_idmap_enabled() &&
+ ksmbd_idmap_sid_mappable(owner_sid_ptr))
+ return -KSMBD_SD_EOWNER;
if (rc) {
ksmbd_debug(SMB, "Owner SID has no Unix uid mapping\n");
owner_sid_ptr = NULL;
@@ -1061,6 +1223,11 @@ int parse_sec_desc(struct mnt_idmap *idmap, struct smb_ntsd *pntsd,
return rc;
}
rc = sid_to_id(idmap, group_sid_ptr, SIDUNIX_GROUP, fattr);
+ if (rc == -EAGAIN)
+ return -KSMBD_SD_EUNAVAIL;
+ if (rc && ksmbd_idmap_enabled() &&
+ ksmbd_idmap_sid_mappable(group_sid_ptr))
+ return -KSMBD_SD_EGROUP;
if (rc) {
ksmbd_debug(SMB, "Group SID has no Unix gid mapping\n");
group_sid_ptr = NULL;
@@ -1083,6 +1250,8 @@ int parse_sec_desc(struct mnt_idmap *idmap, struct smb_ntsd *pntsd,
rc = parse_dacl(idmap, dacl_ptr, end_of_acl,
owner_sid_ptr, group_sid_ptr, fattr);
+ if (rc == -EAGAIN)
+ return -KSMBD_SD_EUNAVAIL;
if (rc)
return rc;
}
@@ -1550,9 +1719,10 @@ bool smb_inherit_flags(int flags, bool is_dir)
}
int smb_check_perm_dacl(struct ksmbd_conn *conn, const struct path *path,
- __le32 *pdaccess, __le32 raw_daccess, kuid_t uid,
- bool strict)
+ __le32 *pdaccess, __le32 raw_daccess,
+ struct ksmbd_user *user, bool strict)
{
+ kuid_t uid = user->kuid;
struct mnt_idmap *idmap = mnt_idmap(path->mnt);
struct smb_ntsd *pntsd = NULL;
struct smb_acl *pdacl;
@@ -1634,7 +1804,7 @@ int smb_check_perm_dacl(struct ksmbd_conn *conn, const struct path *path,
}
if (ace->flags & INHERIT_ONLY_ACE ||
- (compare_sids(&sid, &ace->sid) &&
+ (!sid_names_user(user, &sid, &ace->sid) &&
compare_sids(&sid_unix_NFS_mode, &ace->sid) &&
compare_sids(&sid_everyone, &ace->sid) &&
compare_sids(&sid_authusers, &ace->sid) &&
@@ -1683,7 +1853,7 @@ int smb_check_perm_dacl(struct ksmbd_conn *conn, const struct path *path,
sizeof(__le32) * ace->sid.num_subauth)
break;
- if (!compare_sids(&sid, &ace->sid) ||
+ if (sid_names_user(user, &sid, &ace->sid) ||
!compare_sids(&sid_unix_NFS_mode, &ace->sid)) {
found = 1;
break;
diff --git a/fs/smb/server/smbacl.h b/fs/smb/server/smbacl.h
index d4c9b679d8..fdc70e2b6e 100644
--- a/fs/smb/server/smbacl.h
+++ b/fs/smb/server/smbacl.h
@@ -81,6 +81,16 @@ struct posix_acl_state {
struct posix_ace_state_array *groups;
};
+/*
+ * parse_sec_desc() / set_info_sec() errors about the SIDs of domain
+ * accounts (KSMBD_GLOBAL_FLAG_SID_MAP); ksmbd_sd_err_status() names them.
+ */
+#define KSMBD_SD_EOWNER EBADE /* owner SID: no such user */
+#define KSMBD_SD_EGROUP EBADR /* group SID: no such group */
+#define KSMBD_SD_EUNAVAIL EHOSTDOWN /* user space couldn't map now */
+
+__le32 ksmbd_sd_err_status(int rc);
+
int parse_sec_desc(struct mnt_idmap *idmap, struct smb_ntsd *pntsd,
int acl_len, struct smb_fattr *fattr);
int build_sec_desc(struct mnt_idmap *idmap, struct smb_ntsd *pntsd,
@@ -94,9 +104,11 @@ int compare_sids(const struct smb_sid *ctsid, const struct smb_sid *cwsid);
bool smb_inherit_flags(int flags, bool is_dir);
int smb_inherit_dacl(struct ksmbd_conn *conn, const struct path *path,
kuid_t uid, kgid_t gid);
+struct ksmbd_user;
int smb_check_perm_dacl(struct ksmbd_conn *conn, const struct path *path,
- __le32 *pdaccess, __le32 raw_daccess, kuid_t uid,
- bool strict);
+ __le32 *pdaccess, __le32 raw_daccess,
+ struct ksmbd_user *user, bool strict);
+void ksmbd_user_set_token(struct ksmbd_user *user);
int set_info_sec(struct ksmbd_conn *conn, struct ksmbd_tree_connect *tcon,
const struct path *path, struct smb_ntsd *pntsd, int ntsd_len,
bool get_write);
diff --git a/fs/smb/server/transport_ipc.c b/fs/smb/server/transport_ipc.c
index 4d2f16b96e..7f8124333c 100644
--- a/fs/smb/server/transport_ipc.c
+++ b/fs/smb/server/transport_ipc.c
@@ -17,6 +17,7 @@
#include "vfs_cache.h"
#include "transport_ipc.h"
+#include "idmap.h"
#include "server.h"
#include "smb_common.h"
@@ -131,6 +132,10 @@ static const struct nla_policy ksmbd_nl_policy[KSMBD_EVENT_MAX + 1] = {
NLA_POLICY_MIN_LEN(sizeof(struct ksmbd_ntlm_authen_request)),
[KSMBD_EVENT_NTLM_AUTHEN_RESPONSE] =
NLA_POLICY_EXACT_LEN(sizeof(struct ksmbd_ntlm_authen_response)),
+ [KSMBD_EVENT_SID_MAP_REQUEST] =
+ NLA_POLICY_EXACT_LEN(sizeof(struct ksmbd_sid_map_request)),
+ [KSMBD_EVENT_SID_MAP_RESPONSE] =
+ NLA_POLICY_EXACT_LEN(sizeof(struct ksmbd_sid_map_response)),
};
static struct genl_ops ksmbd_genl_ops[] = {
@@ -214,6 +219,14 @@ static struct genl_ops ksmbd_genl_ops[] = {
.cmd = KSMBD_EVENT_NTLM_AUTHEN_RESPONSE,
.doit = handle_generic_event,
},
+ {
+ .cmd = KSMBD_EVENT_SID_MAP_REQUEST,
+ .doit = handle_unsupported_event,
+ },
+ {
+ .cmd = KSMBD_EVENT_SID_MAP_RESPONSE,
+ .doit = handle_generic_event,
+ },
};
static struct genl_family ksmbd_genl_family = {
@@ -327,6 +340,7 @@ static int ipc_server_config_on_startup(struct ksmbd_startup_request *req)
ksmbd_set_fd_limit(req->file_max);
server_conf.flags = req->flags;
+ ksmbd_idmap_flush(); /* a new user space may map otherwise */
server_conf.signing = req->signing;
server_conf.tcp_port = req->tcp_port;
server_conf.ipc_timeout = req->ipc_timeout * HZ;
@@ -567,6 +581,10 @@ static int ipc_validate_msg(struct ipc_msg_table_entry *entry)
if (entry->msg_sz != sizeof(struct ksmbd_ntlm_authen_response))
return -EINVAL;
break;
+ case KSMBD_EVENT_SID_MAP_REQUEST:
+ if (entry->msg_sz != sizeof(struct ksmbd_sid_map_response))
+ return -EINVAL;
+ break;
case KSMBD_EVENT_LOGIN_REQUEST_EXT:
{
struct ksmbd_login_response_ext *resp = entry->response;
@@ -783,6 +801,48 @@ ksmbd_ipc_ntlm_authen_request(const char *challenge, const char *parts[5],
return resp;
}
+/**
+ * ksmbd_ipc_sid_map_request() - have user space translate an id or a SID
+ * @flags: KSMBD_SID_MAP_TO_SID, KSMBD_SID_MAP_GROUP
+ * @id: with KSMBD_SID_MAP_TO_SID, the id
+ * @sid: without it, the binary SID
+ * @sid_len: its length, at most KSMBD_SID_MAP_SID_SZ
+ *
+ * Only for a user space that set KSMBD_GLOBAL_FLAG_SID_MAP.
+ *
+ * Return: the response (kvfree() it), NULL on error or timeout
+ */
+struct ksmbd_sid_map_response *
+ksmbd_ipc_sid_map_request(unsigned int flags, const struct __kernel_uid_r *id,
+ const void *sid, size_t sid_len)
+{
+ struct ksmbd_ipc_msg *msg;
+ struct ksmbd_sid_map_request *req;
+ struct ksmbd_sid_map_response *resp;
+
+ if (!(server_conf.flags & KSMBD_GLOBAL_FLAG_SID_MAP) ||
+ sid_len > KSMBD_SID_MAP_SID_SZ)
+ return NULL;
+
+ msg = ipc_msg_alloc(sizeof(struct ksmbd_sid_map_request));
+ if (!msg)
+ return NULL;
+
+ msg->type = KSMBD_EVENT_SID_MAP_REQUEST;
+ req = (struct ksmbd_sid_map_request *)msg->payload;
+ req->handle = ksmbd_acquire_id(&ipc_ida);
+ req->flags = flags;
+ if (id)
+ req->id = *id;
+ if (sid)
+ memcpy(req->sid, sid, sid_len);
+
+ resp = ipc_msg_send_request(msg, req->handle);
+ ipc_msg_handle_free(req->handle);
+ ipc_msg_free(msg);
+ return resp;
+}
+
struct ksmbd_tree_connect_response *
ksmbd_ipc_tree_connect_request(struct ksmbd_session *sess,
struct ksmbd_share_config *share,
diff --git a/fs/smb/server/transport_ipc.h b/fs/smb/server/transport_ipc.h
index 1aefa23264..390d9fa800 100644
--- a/fs/smb/server/transport_ipc.h
+++ b/fs/smb/server/transport_ipc.h
@@ -32,6 +32,9 @@ struct ksmbd_share_config_response *
ksmbd_ipc_share_config_request(const char *name);
struct ksmbd_spnego_authen_response *
ksmbd_ipc_spnego_authen_request(const char *spnego_blob, int blob_len);
+struct ksmbd_sid_map_response *
+ksmbd_ipc_sid_map_request(unsigned int flags, const struct __kernel_uid_r *id,
+ const void *sid, size_t sid_len);
struct ksmbd_ntlm_authen_response *
ksmbd_ipc_ntlm_authen_request(const char *challenge, const char *parts[5],
const unsigned short lens[5]);
--
2.56.0
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2026-11-10 9:01 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
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2026-11-10 9:02 [RFC PATCH 4/6] ksmbd: map user and group ids to Windows SIDs through user space Jan Koester
-- strict thread matches above, loose matches on Subject: below --
2026-10-28 6:19 [RFC PATCH 0/6] ksmbd: Windows SIDs for user and group ids Jan Koester
2026-10-28 6:20 ` [RFC PATCH 4/6] ksmbd: map user and group ids to Windows SIDs through user space Jan Koester
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