linux/fs/cifs/cifsacl.h

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/*
* fs/cifs/cifsacl.h
*
* Copyright (c) International Business Machines Corp., 2007
* Author(s): Steve French (sfrench@us.ibm.com)
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
* the GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef _CIFSACL_H
#define _CIFSACL_H
#define NUM_AUTHS (6) /* number of authority fields */
#define SID_MAX_SUB_AUTHORITIES (15) /* max number of sub authority fields */
#define READ_BIT 0x4
#define WRITE_BIT 0x2
#define EXEC_BIT 0x1
#define UBITSHIFT 6
#define GBITSHIFT 3
#define ACCESS_ALLOWED 0
#define ACCESS_DENIED 1
cifs: Invoke id mapping functions (try #17 repost) rb tree search and insertion routines. A SID which needs to be mapped, is looked up in one of the rb trees depending on whether SID is either owner or group SID. If found in the tree, a (mapped) id from that node is assigned to uid or gid as appropriate. If unmapped, an upcall is attempted to map the SID to an id. If upcall is successful, node is marked as mapped. If upcall fails, node stays marked as unmapped and a mapping is attempted again only after an arbitrary time period has passed. To map a SID, which can be either a Owner SID or a Group SID, key description starts with the string "os" or "gs" followed by SID converted to a string. Without "os" or "gs", cifs.upcall does not know whether SID needs to be mapped to either an uid or a gid. Nodes in rb tree have fields to prevent multiple upcalls for a SID. Searching, adding, and removing nodes is done within global locks. Whenever a node is either found or inserted in a tree, a reference is taken on that node. Shrinker routine prunes a node if it has expired but does not prune an expired node if its refcount is not zero (i.e. sid/id of that node is_being/will_be accessed). Thus a node, if its SID needs to be mapped by making an upcall, can safely stay and its fields accessed without shrinker pruning it. A reference (refcount) is put on the node without holding the spinlock but a reference is get on the node by holding the spinlock. Every time an existing mapped node is accessed or mapping is attempted, its timestamp is updated to prevent it from getting erased or a to prevent multiple unnecessary repeat mapping retries respectively. For now, cifs.upcall is only used to map a SID to an id (uid or gid) but it would be used to obtain an SID for an id. Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com> Reviewed-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Steve French <sfrench@us.ibm.com>
2011-04-23 01:09:36 +08:00
#define SIDOWNER 1
#define SIDGROUP 2
/*
* Security Descriptor length containing DACL with 3 ACEs (one each for
* owner, group and world).
*/
#define DEFAULT_SEC_DESC_LEN (sizeof(struct cifs_ntsd) + \
sizeof(struct cifs_acl) + \
(sizeof(struct cifs_ace) * 3))
/*
* Maximum size of a string representation of a SID:
*
* The fields are unsigned values in decimal. So:
*
* u8: max 3 bytes in decimal
* u32: max 10 bytes in decimal
*
* "S-" + 3 bytes for version field + 15 for authority field + NULL terminator
*
* For authority field, max is when all 6 values are non-zero and it must be
* represented in hex. So "-0x" + 12 hex digits.
*
* Add 11 bytes for each subauthority field (10 bytes each + 1 for '-')
*/
#define SID_STRING_BASE_SIZE (2 + 3 + 15 + 1)
#define SID_STRING_SUBAUTH_SIZE (11) /* size of a single subauth string */
cifs: Invoke id mapping functions (try #17 repost) rb tree search and insertion routines. A SID which needs to be mapped, is looked up in one of the rb trees depending on whether SID is either owner or group SID. If found in the tree, a (mapped) id from that node is assigned to uid or gid as appropriate. If unmapped, an upcall is attempted to map the SID to an id. If upcall is successful, node is marked as mapped. If upcall fails, node stays marked as unmapped and a mapping is attempted again only after an arbitrary time period has passed. To map a SID, which can be either a Owner SID or a Group SID, key description starts with the string "os" or "gs" followed by SID converted to a string. Without "os" or "gs", cifs.upcall does not know whether SID needs to be mapped to either an uid or a gid. Nodes in rb tree have fields to prevent multiple upcalls for a SID. Searching, adding, and removing nodes is done within global locks. Whenever a node is either found or inserted in a tree, a reference is taken on that node. Shrinker routine prunes a node if it has expired but does not prune an expired node if its refcount is not zero (i.e. sid/id of that node is_being/will_be accessed). Thus a node, if its SID needs to be mapped by making an upcall, can safely stay and its fields accessed without shrinker pruning it. A reference (refcount) is put on the node without holding the spinlock but a reference is get on the node by holding the spinlock. Every time an existing mapped node is accessed or mapping is attempted, its timestamp is updated to prevent it from getting erased or a to prevent multiple unnecessary repeat mapping retries respectively. For now, cifs.upcall is only used to map a SID to an id (uid or gid) but it would be used to obtain an SID for an id. Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com> Reviewed-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Steve French <sfrench@us.ibm.com>
2011-04-23 01:09:36 +08:00
struct cifs_ntsd {
__le16 revision; /* revision level */
__le16 type;
__le32 osidoffset;
__le32 gsidoffset;
__le32 sacloffset;
__le32 dacloffset;
} __attribute__((packed));
struct cifs_sid {
__u8 revision; /* revision level */
__u8 num_subauth;
__u8 authority[NUM_AUTHS];
__le32 sub_auth[SID_MAX_SUB_AUTHORITIES]; /* sub_auth[num_subauth] */
} __attribute__((packed));
/* size of a struct cifs_sid, sans sub_auth array */
#define CIFS_SID_BASE_SIZE (1 + 1 + NUM_AUTHS)
struct cifs_acl {
__le16 revision; /* revision level */
__le16 size;
__le32 num_aces;
} __attribute__((packed));
struct cifs_ace {
__u8 type;
__u8 flags;
__le16 size;
__le32 access_req;
struct cifs_sid sid; /* ie UUID of user or group who gets these perms */
} __attribute__((packed));
/*
* Minimum security identifier can be one for system defined Users
* and Groups such as NULL SID and World or Built-in accounts such
* as Administrator and Guest and consists of
* Revision + Num (Sub)Auths + Authority + Domain (one Subauthority)
*/
#define MIN_SID_LEN (1 + 1 + 6 + 4) /* in bytes */
/*
* Minimum security descriptor can be one without any SACL and DACL and can
* consist of revision, type, and two sids of minimum size for owner and group
*/
#define MIN_SEC_DESC_LEN (sizeof(struct cifs_ntsd) + (2 * MIN_SID_LEN))
#endif /* _CIFSACL_H */