linux/fs/cifs/cifsacl.c

/*
 *   fs/cifs/cifsacl.c
 *
 *   Copyright (C) International Business Machines  Corp., 2007
 *   Author(s): Steve French (sfrench@us.ibm.com)
 *
 *   Contains the routines for mapping CIFS/NTFS ACLs
 *
 *   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
 */

#include <linux/fs.h>
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifsacl.h"
#include "cifsproto.h"
#include "cifs_debug.h"


#ifdef CONFIG_CIFS_EXPERIMENTAL

static struct cifs_wksid wksidarr[NUM_WK_SIDS] = {
	{{1, 0, {0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 0} }, "null user"},
	{{1, 1, {0, 0, 0, 0, 0, 1}, {0, 0, 0, 0, 0} }, "nobody"},
	{{1, 1, {0, 0, 0, 0, 0, 5}, {cpu_to_le32(11), 0, 0, 0, 0} }, "net-users"},
	{{1, 1, {0, 0, 0, 0, 0, 5}, {cpu_to_le32(18), 0, 0, 0, 0} }, "sys"},
	{{1, 2, {0, 0, 0, 0, 0, 5}, {cpu_to_le32(32), cpu_to_le32(544), 0, 0, 0} }, "root"},
	{{1, 2, {0, 0, 0, 0, 0, 5}, {cpu_to_le32(32), cpu_to_le32(545), 0, 0, 0} }, "users"},
	{{1, 2, {0, 0, 0, 0, 0, 5}, {cpu_to_le32(32), cpu_to_le32(546), 0, 0, 0} }, "guest"} }
;


/* security id for everyone */
static const struct cifs_sid sid_everyone = {
	1, 1, {0, 0, 0, 0, 0, 1}, {0} };
/* group users */
static const struct cifs_sid sid_user =
		{1, 2 , {0, 0, 0, 0, 0, 5}, {} };


int match_sid(struct cifs_sid *ctsid)
{
	int i, j;
	int num_subauth, num_sat, num_saw;
	struct cifs_sid *cwsid;

	if (!ctsid)
		return (-1);

	for (i = 0; i < NUM_WK_SIDS; ++i) {
		cwsid = &(wksidarr[i].cifssid);

		/* compare the revision */
		if (ctsid->revision != cwsid->revision)
			continue;

		/* compare all of the six auth values */
		for (j = 0; j < 6; ++j) {
			if (ctsid->authority[j] != cwsid->authority[j])
				break;
		}
		if (j < 6)
			continue; /* all of the auth values did not match */

		/* compare all of the subauth values if any */
		num_sat = ctsid->num_subauth;
		num_saw = cwsid->num_subauth;
		num_subauth = num_sat < num_saw ? num_sat : num_saw;
		if (num_subauth) {
			for (j = 0; j < num_subauth; ++j) {
				if (ctsid->sub_auth[j] != cwsid->sub_auth[j])
					break;
			}
			if (j < num_subauth)
				continue; /* all sub_auth values do not match */
		}

		cFYI(1, ("matching sid: %s\n", wksidarr[i].sidname));
		return (0); /* sids compare/match */
	}

	cFYI(1, ("No matching sid"));
	return (-1);
}

/* if the two SIDs (roughly equivalent to a UUID for a user or group) are
   the same returns 1, if they do not match returns 0 */
int compare_sids(const struct cifs_sid *ctsid, const struct cifs_sid *cwsid)
{
	int i;
	int num_subauth, num_sat, num_saw;

	if ((!ctsid) || (!cwsid))
		return (0);

	/* compare the revision */
	if (ctsid->revision != cwsid->revision)
		return (0);

	/* compare all of the six auth values */
	for (i = 0; i < 6; ++i) {
		if (ctsid->authority[i] != cwsid->authority[i])
			return (0);
	}

	/* compare all of the subauth values if any */
	num_sat = ctsid->num_subauth;
	num_saw = cwsid->num_subauth;
	num_subauth = num_sat < num_saw ? num_sat : num_saw;
	if (num_subauth) {
		for (i = 0; i < num_subauth; ++i) {
			if (ctsid->sub_auth[i] != cwsid->sub_auth[i])
				return (0);
		}
	}

	return (1); /* sids compare/match */
}

/*
   change posix mode to reflect permissions
   pmode is the existing mode (we only want to overwrite part of this
   bits to set can be: S_IRWXU, S_IRWXG or S_IRWXO ie 00700 or 00070 or 00007
*/
static void access_flags_to_mode(__u32 ace_flags, int type, umode_t *pmode,
				 umode_t *pbits_to_set)
{
	/* the order of ACEs is important.  The canonical order is to begin with
	   DENY entries followed by ALLOW, otherwise an allow entry could be
	   encountered first, making the subsequent deny entry like "dead code"
	   which would be superflous since Windows stops when a match is made
	   for the operation you are trying to perform for your user */

	/* For deny ACEs we change the mask so that subsequent allow access
	   control entries do not turn on the bits we are denying */
	if (type == ACCESS_DENIED) {
		if (ace_flags & GENERIC_ALL) {
			*pbits_to_set &= ~S_IRWXUGO;
		}
		if ((ace_flags & GENERIC_WRITE) ||
			((ace_flags & FILE_WRITE_RIGHTS) == FILE_WRITE_RIGHTS))
			*pbits_to_set &= ~S_IWUGO;
		if ((ace_flags & GENERIC_READ) ||
			((ace_flags & FILE_READ_RIGHTS) == FILE_READ_RIGHTS))
			*pbits_to_set &= ~S_IRUGO;
		if ((ace_flags & GENERIC_EXECUTE) ||
			((ace_flags & FILE_EXEC_RIGHTS) == FILE_EXEC_RIGHTS))
			*pbits_to_set &= ~S_IXUGO;
		return;
	} else if (type != ACCESS_ALLOWED) {
		cERROR(1, ("unknown access control type %d", type));
		return;
	}
	/* else ACCESS_ALLOWED type */

	if (ace_flags & GENERIC_ALL) {
		*pmode |= (S_IRWXUGO & (*pbits_to_set));
#ifdef CONFIG_CIFS_DEBUG2
		cFYI(1, ("all perms"));
#endif
		return;
	}
	if ((ace_flags & GENERIC_WRITE) ||
			((ace_flags & FILE_WRITE_RIGHTS) == FILE_WRITE_RIGHTS))
		*pmode |= (S_IWUGO & (*pbits_to_set));
	if ((ace_flags & GENERIC_READ) ||
			((ace_flags & FILE_READ_RIGHTS) == FILE_READ_RIGHTS))
		*pmode |= (S_IRUGO & (*pbits_to_set));
	if ((ace_flags & GENERIC_EXECUTE) ||
			((ace_flags & FILE_EXEC_RIGHTS) == FILE_EXEC_RIGHTS))
		*pmode |= (S_IXUGO & (*pbits_to_set));

#ifdef CONFIG_CIFS_DEBUG2
	cFYI(1, ("access flags 0x%x mode now 0x%x", ace_flags, *pmode));
#endif
	return;
}

/*
   Generate access flags to reflect permissions mode is the existing mode.
   This function is called for every ACE in the DACL whose SID matches
   with either owner or group or everyone.
*/

static void mode_to_access_flags(umode_t mode, umode_t bits_to_use,
				__u32 *pace_flags)
{
	/* reset access mask */
	*pace_flags = 0x0;

	/* bits to use are either S_IRWXU or S_IRWXG or S_IRWXO */
	mode &= bits_to_use;

	/* check for R/W/X UGO since we do not know whose flags
	   is this but we have cleared all the bits sans RWX for
	   either user or group or other as per bits_to_use */
	if (mode & S_IRUGO)
		*pace_flags |= SET_FILE_READ_RIGHTS;
	if (mode & S_IWUGO)
		*pace_flags |= SET_FILE_WRITE_RIGHTS;
	if (mode & S_IXUGO)
		*pace_flags |= SET_FILE_EXEC_RIGHTS;

#ifdef CONFIG_CIFS_DEBUG2
	cFYI(1, ("mode: 0x%x, access flags now 0x%x", mode, *pace_flags));
#endif
	return;
}


#ifdef CONFIG_CIFS_DEBUG2
static void dump_ace(struct cifs_ace *pace, char *end_of_acl)
{
	int num_subauth;

	/* validate that we do not go past end of acl */

	if (le16_to_cpu(pace->size) < 16) {
		cERROR(1, ("ACE too small, %d", le16_to_cpu(pace->size)));
		return;
	}

	if (end_of_acl < (char *)pace + le16_to_cpu(pace->size)) {
		cERROR(1, ("ACL too small to parse ACE"));
		return;
	}

	num_subauth = pace->sid.num_subauth;
	if (num_subauth) {
		int i;
		cFYI(1, ("ACE revision %d num_auth %d type %d flags %d size %d",
			pace->sid.revision, pace->sid.num_subauth, pace->type,
			pace->flags, pace->size));
		for (i = 0; i < num_subauth; ++i) {
			cFYI(1, ("ACE sub_auth[%d]: 0x%x", i,
				le32_to_cpu(pace->sid.sub_auth[i])));
		}

		/* BB add length check to make sure that we do not have huge
			num auths and therefore go off the end */
	}

	return;
}
#endif


static void parse_dacl(struct cifs_acl *pdacl, char *end_of_acl,
		       struct cifs_sid *pownersid, struct cifs_sid *pgrpsid,
		       struct inode *inode)
{
	int i;
	int num_aces = 0;
	int acl_size;
	char *acl_base;
	struct cifs_ace **ppace;

	/* BB need to add parm so we can store the SID BB */

	/* validate that we do not go past end of acl */
	if (end_of_acl < (char *)pdacl + le16_to_cpu(pdacl->size)) {
		cERROR(1, ("ACL too small to parse DACL"));
		return;
	}

#ifdef CONFIG_CIFS_DEBUG2
	cFYI(1, ("DACL revision %d size %d num aces %d",
		le16_to_cpu(pdacl->revision), le16_to_cpu(pdacl->size),
		le32_to_cpu(pdacl->num_aces)));
#endif

	/* reset rwx permissions for user/group/other.
	   Also, if num_aces is 0 i.e. DACL has no ACEs,
	   user/group/other have no permissions */
	inode->i_mode &= ~(S_IRWXUGO);

	if (!pdacl) {
		/* no DACL in the security descriptor, set
		   all the permissions for user/group/other */
		inode->i_mode |= S_IRWXUGO;
		return;
	}
	acl_base = (char *)pdacl;
	acl_size = sizeof(struct cifs_acl);

	num_aces = le32_to_cpu(pdacl->num_aces);
	if (num_aces  > 0) {
		umode_t user_mask = S_IRWXU;
		umode_t group_mask = S_IRWXG;
		umode_t other_mask = S_IRWXO;

		ppace = kmalloc(num_aces * sizeof(struct cifs_ace *),
				GFP_KERNEL);

/*		cifscred->cecount = pdacl->num_aces;
		cifscred->aces = kmalloc(num_aces *
			sizeof(struct cifs_ace *), GFP_KERNEL);*/

		for (i = 0; i < num_aces; ++i) {
			ppace[i] = (struct cifs_ace *) (acl_base + acl_size);
#ifdef CONFIG_CIFS_DEBUG2
			dump_ace(ppace[i], end_of_acl);
#endif
			if (compare_sids(&(ppace[i]->sid), pownersid))
				access_flags_to_mode(ppace[i]->access_req,
						     ppace[i]->type,
						     &(inode->i_mode),
						     &user_mask);
			if (compare_sids(&(ppace[i]->sid), pgrpsid))
				access_flags_to_mode(ppace[i]->access_req,
						     ppace[i]->type,
						     &(inode->i_mode),
						     &group_mask);
			if (compare_sids(&(ppace[i]->sid), &sid_everyone))
				access_flags_to_mode(ppace[i]->access_req,
						     ppace[i]->type,
						     &(inode->i_mode),
						     &other_mask);

/*			memcpy((void *)(&(cifscred->aces[i])),
				(void *)ppace[i],
				sizeof(struct cifs_ace)); */

			acl_base = (char *)ppace[i];
			acl_size = le16_to_cpu(ppace[i]->size);
		}

		kfree(ppace);
	}

	return;
}


static int parse_sid(struct cifs_sid *psid, char *end_of_acl)
{
	/* BB need to add parm so we can store the SID BB */

	/* validate that we do not go past end of ACL - sid must be at least 8
	   bytes long (assuming no sub-auths - e.g. the null SID */
	if (end_of_acl < (char *)psid + 8) {
		cERROR(1, ("ACL too small to parse SID %p", psid));
		return -EINVAL;
	}

	if (psid->num_subauth) {
#ifdef CONFIG_CIFS_DEBUG2
		int i;
		cFYI(1, ("SID revision %d num_auth %d",
			psid->revision, psid->num_subauth));

		for (i = 0; i < psid->num_subauth; i++) {
			cFYI(1, ("SID sub_auth[%d]: 0x%x ", i,
				le32_to_cpu(psid->sub_auth[i])));
		}

		/* BB add length check to make sure that we do not have huge
			num auths and therefore go off the end */
		cFYI(1, ("RID 0x%x",
			le32_to_cpu(psid->sub_auth[psid->num_subauth-1])));
#endif
	}

	return 0;
}


/* Convert CIFS ACL to POSIX form */
static int parse_sec_desc(struct cifs_ntsd *pntsd, int acl_len,
			  struct inode *inode)
{
	int rc;
	struct cifs_sid *owner_sid_ptr, *group_sid_ptr;
	struct cifs_acl *dacl_ptr; /* no need for SACL ptr */
	char *end_of_acl = ((char *)pntsd) + acl_len;
	__u32 dacloffset;

	if ((inode == NULL) || (pntsd == NULL))
		return -EIO;

	owner_sid_ptr = (struct cifs_sid *)((char *)pntsd +
				le32_to_cpu(pntsd->osidoffset));
	group_sid_ptr = (struct cifs_sid *)((char *)pntsd +
				le32_to_cpu(pntsd->gsidoffset));
	dacloffset = le32_to_cpu(pntsd->dacloffset);
	dacl_ptr = (struct cifs_acl *)((char *)pntsd + dacloffset);
#ifdef CONFIG_CIFS_DEBUG2
	cFYI(1, ("revision %d type 0x%x ooffset 0x%x goffset 0x%x "
		 "sacloffset 0x%x dacloffset 0x%x",
		 pntsd->revision, pntsd->type, le32_to_cpu(pntsd->osidoffset),
		 le32_to_cpu(pntsd->gsidoffset),
		 le32_to_cpu(pntsd->sacloffset), dacloffset));
#endif
/*	cifs_dump_mem("owner_sid: ", owner_sid_ptr, 64); */
	rc = parse_sid(owner_sid_ptr, end_of_acl);
	if (rc)
		return rc;

	rc = parse_sid(group_sid_ptr, end_of_acl);
	if (rc)
		return rc;

	if (dacloffset)
		parse_dacl(dacl_ptr, end_of_acl, owner_sid_ptr,
			   group_sid_ptr, inode);
	else
		cFYI(1, ("no ACL")); /* BB grant all or default perms? */

/*	cifscred->uid = owner_sid_ptr->rid;
	cifscred->gid = group_sid_ptr->rid;
	memcpy((void *)(&(cifscred->osid)), (void *)owner_sid_ptr,
			sizeof(struct cifs_sid));
	memcpy((void *)(&(cifscred->gsid)), (void *)group_sid_ptr,
			sizeof(struct cifs_sid)); */


	return (0);
}


/* Retrieve an ACL from the server */
static struct cifs_ntsd *get_cifs_acl(u32 *pacllen, struct inode *inode,
				       const char *path)
{
	struct cifsFileInfo *open_file;
	int unlock_file = FALSE;
	int xid;
	int rc = -EIO;
	__u16 fid;
	struct super_block *sb;
	struct cifs_sb_info *cifs_sb;
	struct cifs_ntsd *pntsd = NULL;

	cFYI(1, ("get mode from ACL for %s", path));

	if (inode == NULL)
		return NULL;

	xid = GetXid();
	open_file = find_readable_file(CIFS_I(inode));
	sb = inode->i_sb;
	if (sb == NULL) {
		FreeXid(xid);
		return NULL;
	}
	cifs_sb = CIFS_SB(sb);

	if (open_file) {
		unlock_file = TRUE;
		fid = open_file->netfid;
	} else {
		int oplock = FALSE;
		/* open file */
		rc = CIFSSMBOpen(xid, cifs_sb->tcon, path, FILE_OPEN,
				READ_CONTROL, 0, &fid, &oplock, NULL,
				cifs_sb->local_nls, cifs_sb->mnt_cifs_flags &
					CIFS_MOUNT_MAP_SPECIAL_CHR);
		if (rc != 0) {
			cERROR(1, ("Unable to open file to get ACL"));
			FreeXid(xid);
			return NULL;
		}
	}

	rc = CIFSSMBGetCIFSACL(xid, cifs_sb->tcon, fid, &pntsd, pacllen);
	cFYI(1, ("GetCIFSACL rc = %d ACL len %d", rc, *pacllen));
	if (unlock_file == TRUE)
		atomic_dec(&open_file->wrtPending);
	else
		CIFSSMBClose(xid, cifs_sb->tcon, fid);

	FreeXid(xid);
	return pntsd;
}

/* Translate the CIFS ACL (simlar to NTFS ACL) for a file into mode bits */
void acl_to_uid_mode(struct inode *inode, const char *path)
{
	struct cifs_ntsd *pntsd = NULL;
	u32 acllen = 0;
	int rc = 0;

#ifdef CONFIG_CIFS_DEBUG2
	cFYI(1, ("converting ACL to mode for %s", path));
#endif
	pntsd = get_cifs_acl(&acllen, inode, path);

	/* if we can retrieve the ACL, now parse Access Control Entries, ACEs */
	if (pntsd)
		rc = parse_sec_desc(pntsd, acllen, inode);
	if (rc)
		cFYI(1, ("parse sec desc failed rc = %d", rc));

	kfree(pntsd);
	return;
}

/* Convert mode bits to an ACL so we can update the ACL on the server */
int mode_to_acl(struct inode *inode, const char *path)
{
	int rc = 0;
	__u32 acllen = 0;
	struct cifs_ntsd *pntsd = NULL;

	cFYI(1, ("set ACL from mode for %s", path));

	/* Get the security descriptor */
	pntsd = get_cifs_acl(&acllen, inode, path);

	/* Add/Modify the three ACEs for owner, group, everyone
	   while retaining the other ACEs */

	/* Set the security descriptor */


	kfree(pntsd);
	return rc;
}
#endif /* CONFIG_CIFS_EXPERIMENTAL */