forked from Minki/linux
faa65f07d2
The cifs.idmap handling code currently causes the kernel to cache the data from userspace twice. It first looks in a rbtree to see if there is a matching entry for the given id. If there isn't then it calls request_key which then checks its cache and then calls out to userland if it doesn't have one. If the userland program establishes a mapping and downcalls with that info, it then gets cached in the keyring and in this rbtree. Aside from the double memory usage and the performance penalty in doing all of these extra copies, there are some nasty bugs in here too. The code declares four rbtrees and spinlocks to protect them, but only seems to use two of them. The upshot is that the same tree is used to hold (eg) uid:sid and sid:uid mappings. The comparitors aren't equipped to deal with that. I think we'd be best off to remove a layer of caching in this code. If this was originally done for performance reasons, then that really seems like a premature optimization. This patch does that -- it removes the rbtrees and the locks that protect them and simply has the code do a request_key call on each call into sid_to_id and id_to_sid. This greatly simplifies this code and should roughly halve the memory utilization from using the idmapping code. Reviewed-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com> Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Steve French <smfrench@gmail.com>
95 lines
2.8 KiB
C
95 lines
2.8 KiB
C
/*
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* fs/cifs/cifsacl.h
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*
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* Copyright (c) International Business Machines Corp., 2007
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* Author(s): Steve French (sfrench@us.ibm.com)
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*
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* This library is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published
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* by the Free Software Foundation; either version 2.1 of the License, or
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* (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
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* the GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#ifndef _CIFSACL_H
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#define _CIFSACL_H
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#define NUM_AUTHS (6) /* number of authority fields */
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#define SID_MAX_SUB_AUTHORITIES (15) /* max number of sub authority fields */
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#define NUM_WK_SIDS 7 /* number of well known sids */
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#define SIDNAMELENGTH 20 /* long enough for the ones we care about */
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#define DEFSECDESCLEN 192 /* sec desc len contaiting a dacl with three aces */
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#define READ_BIT 0x4
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#define WRITE_BIT 0x2
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#define EXEC_BIT 0x1
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#define UBITSHIFT 6
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#define GBITSHIFT 3
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#define ACCESS_ALLOWED 0
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#define ACCESS_DENIED 1
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#define SIDOWNER 1
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#define SIDGROUP 2
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/*
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* Maximum size of a string representation of a SID:
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*
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* The fields are unsigned values in decimal. So:
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*
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* u8: max 3 bytes in decimal
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* u32: max 10 bytes in decimal
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*
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* "S-" + 3 bytes for version field + 4 bytes for each authority field (3 bytes
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* per number + 1 for '-') + NULL terminator.
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*
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* Add 11 bytes for each subauthority field (10 bytes each + 1 for '-')
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*/
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#define SID_STRING_BASE_SIZE (2 + 3 + (4 * NUM_AUTHS) + 1)
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#define SID_STRING_SUBAUTH_SIZE (11) /* size of a single subauth string */
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struct cifs_ntsd {
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__le16 revision; /* revision level */
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__le16 type;
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__le32 osidoffset;
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__le32 gsidoffset;
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__le32 sacloffset;
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__le32 dacloffset;
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} __attribute__((packed));
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struct cifs_sid {
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__u8 revision; /* revision level */
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__u8 num_subauth;
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__u8 authority[NUM_AUTHS];
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__le32 sub_auth[SID_MAX_SUB_AUTHORITIES]; /* sub_auth[num_subauth] */
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} __attribute__((packed));
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/* size of a struct cifs_sid, sans sub_auth array */
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#define CIFS_SID_BASE_SIZE (1 + 1 + NUM_AUTHS)
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struct cifs_acl {
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__le16 revision; /* revision level */
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__le16 size;
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__le32 num_aces;
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} __attribute__((packed));
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struct cifs_ace {
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__u8 type;
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__u8 flags;
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__le16 size;
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__le32 access_req;
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struct cifs_sid sid; /* ie UUID of user or group who gets these perms */
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} __attribute__((packed));
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#endif /* _CIFSACL_H */
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