acls.c

Rsync 3.0.5 source code

/*
 * Handle passing Access Control Lists between systems.
 *
 * Copyright (C) 1996 Andrew Tridgell
 * Copyright (C) 1996 Paul Mackerras
 * Copyright (C) 2006-2008 Wayne Davison
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, visit the http://fsf.org website.
 */

#include "rsync.h"
#include "lib/sysacls.h"

#ifdef SUPPORT_ACLS

extern int dry_run;
extern int am_root;
extern int read_only;
extern int list_only;
extern int orig_umask;
extern int numeric_ids;
extern int inc_recurse;

/* Flags used to indicate what items are being transmitted for an entry. */
#define XMIT_USER_OBJ (1<<0)
#define XMIT_GROUP_OBJ (1<<1)
#define XMIT_MASK_OBJ (1<<2)
#define XMIT_OTHER_OBJ (1<<3)
#define XMIT_NAME_LIST (1<<4)

#define NO_ENTRY ((uchar)0x80) /* Default value of a NON-name-list entry. */

#define NAME_IS_USER (1u<<31) /* Bit used only on a name-list entry. */

/* When we send the access bits over the wire, we shift them 2 bits to the
 * left and use the lower 2 bits as flags (relevant only to a name entry).
 * This makes the protocol more efficient than sending a value that would
 * be likely to have its hightest bits set. */
#define XFLAG_NAME_FOLLOWS 0x0001u
#define XFLAG_NAME_IS_USER 0x0002u

/* === ACL structures === */

typedef struct {
	id_t id;
	uint32 access;
} id_access;

typedef struct {
	id_access *idas;
	int count;
} ida_entries;

typedef struct {
	char *name;
	uchar len;
} idname;

typedef struct rsync_acl {
	ida_entries names;
	/* These will be NO_ENTRY if there's no such entry. */
	uchar user_obj;
	uchar group_obj;
	uchar mask_obj;
	uchar other_obj;
} rsync_acl;

typedef struct {
	rsync_acl racl;
	SMB_ACL_T sacl;
} acl_duo;

static const rsync_acl empty_rsync_acl = {
	{NULL, 0}, NO_ENTRY, NO_ENTRY, NO_ENTRY, NO_ENTRY
};

static item_list access_acl_list = EMPTY_ITEM_LIST;
static item_list default_acl_list = EMPTY_ITEM_LIST;

/* === Calculations on ACL types === */

static const char *str_acl_type(SMB_ACL_TYPE_T type)
{
	switch (type) {
	case SMB_ACL_TYPE_ACCESS:
#ifdef HAVE_OSX_ACLS
		return "ACL_TYPE_EXTENDED";
#else
		return "ACL_TYPE_ACCESS";
#endif
	case SMB_ACL_TYPE_DEFAULT:
		return "ACL_TYPE_DEFAULT";
	default:
		break;
	}
	return "unknown ACL type!";
}

static int calc_sacl_entries(const rsync_acl *racl)
{
	/* A System ACL always gets user/group/other permission entries. */
	return racl->names.count
#ifdef ACLS_NEED_MASK
	     + 4;
#else
	     + (racl->mask_obj != NO_ENTRY) + 3;
#endif
}

/* Extracts and returns the permission bits from the ACL.  This cannot be
 * called on an rsync_acl that has NO_ENTRY in any spot but the mask. */
static int rsync_acl_get_perms(const rsync_acl *racl)
{
	return (racl->user_obj << 6)
	     + ((racl->mask_obj != NO_ENTRY ? racl->mask_obj : racl->group_obj) << 3)
	     + racl->other_obj;
}

/* Removes the permission-bit entries from the ACL because these
 * can be reconstructed from the file's mode. */
static void rsync_acl_strip_perms(rsync_acl *racl)
{
	racl->user_obj = NO_ENTRY;
	if (racl->mask_obj == NO_ENTRY)
		racl->group_obj = NO_ENTRY;
	else {
		if (racl->group_obj == racl->mask_obj)
			racl->group_obj = NO_ENTRY;
		racl->mask_obj = NO_ENTRY;
	}
	racl->other_obj = NO_ENTRY;
}

/* Given an empty rsync_acl, fake up the permission bits. */
static void rsync_acl_fake_perms(rsync_acl *racl, mode_t mode)
{
	racl->user_obj = (mode >> 6) & 7;
	racl->group_obj = (mode >> 3) & 7;
	racl->other_obj = mode & 7;
}

/* === Rsync ACL functions === */

static rsync_acl *create_racl(void)
{
	rsync_acl *racl = new(rsync_acl);

	if (!racl)
		out_of_memory("create_racl");
	*racl = empty_rsync_acl;

	return racl;
}

static BOOL ida_entries_equal(const ida_entries *ial1, const ida_entries *ial2)
{
	id_access *ida1, *ida2;
	int count = ial1->count;
	if (count != ial2->count)
		return False;
	ida1 = ial1->idas;
	ida2 = ial2->idas;
	for (; count--; ida1++, ida2++) {
		if (ida1->access != ida2->access || ida1->id != ida2->id)
			return False;
	}
	return True;
}

static BOOL rsync_acl_equal(const rsync_acl *racl1, const rsync_acl *racl2)
{
	return racl1->user_obj == racl2->user_obj
	    && racl1->group_obj == racl2->group_obj
	    && racl1->mask_obj == racl2->mask_obj
	    && racl1->other_obj == racl2->other_obj
	    && ida_entries_equal(&racl1->names, &racl2->names);
}

/* Are the extended (non-permission-bit) entries equal?  If so, the rest of
 * the ACL will be handled by the normal mode-preservation code.  This is
 * only meaningful for access ACLs!  Note: the 1st arg is a fully-populated
 * rsync_acl, but the 2nd parameter can be a condensed rsync_acl, which means
 * that it might have several of its permission objects set to NO_ENTRY. */
static BOOL rsync_acl_equal_enough(const rsync_acl *racl1,
				   const rsync_acl *racl2, mode_t m)
{
	if ((racl1->mask_obj ^ racl2->mask_obj) & NO_ENTRY)
		return False; /* One has a mask and the other doesn't */

	/* When there's a mask, the group_obj becomes an extended entry. */
	if (racl1->mask_obj != NO_ENTRY) {
		/* A condensed rsync_acl with a mask can only have no
		 * group_obj when it was identical to the mask.  This
		 * means that it was also identical to the group attrs
		 * from the mode. */
		if (racl2->group_obj == NO_ENTRY) {
			if (racl1->group_obj != ((m >> 3) & 7))
				return False;
		} else if (racl1->group_obj != racl2->group_obj)
			return False;
	}
	return ida_entries_equal(&racl1->names, &racl2->names);
}

static void rsync_acl_free(rsync_acl *racl)
{
	if (racl->names.idas)
		free(racl->names.idas);
	*racl = empty_rsync_acl;
}

void free_acl(stat_x *sxp)
{
	if (sxp->acc_acl) {
		rsync_acl_free(sxp->acc_acl);
		free(sxp->acc_acl);
		sxp->acc_acl = NULL;
	}
	if (sxp->def_acl) {
		rsync_acl_free(sxp->def_acl);
		free(sxp->def_acl);
		sxp->def_acl = NULL;
	}
}

#ifdef SMB_ACL_NEED_SORT
static int id_access_sorter(const void *r1, const void *r2)
{
	id_access *ida1 = (id_access *)r1;
	id_access *ida2 = (id_access *)r2;
	id_t rid1 = ida1->id, rid2 = ida2->id;
	if ((ida1->access ^ ida2->access) & NAME_IS_USER)
		return ida1->access & NAME_IS_USER ? -1 : 1;
	return rid1 == rid2 ? 0 : rid1 < rid2 ? -1 : 1;
}
#endif

/* === System ACLs === */

/* Unpack system ACL -> rsync ACL verbatim.  Return whether we succeeded. */
static BOOL unpack_smb_acl(SMB_ACL_T sacl, rsync_acl *racl)
{
	static item_list temp_ida_list = EMPTY_ITEM_LIST;
	SMB_ACL_ENTRY_T entry;
	const char *errfun;
	int rc;

	errfun = "sys_acl_get_entry";
	for (rc = sys_acl_get_entry(sacl, SMB_ACL_FIRST_ENTRY, &entry);
	     rc == 1;
	     rc = sys_acl_get_entry(sacl, SMB_ACL_NEXT_ENTRY, &entry)) {
		SMB_ACL_TAG_T tag_type;
		uint32 access;
		id_t g_u_id;
		id_access *ida;
		if ((rc = sys_acl_get_info(entry, &tag_type, &access, &g_u_id)) != 0) {
			errfun = "sys_acl_get_info";
			break;
		}
		/* continue == done with entry; break == store in temporary ida list */
		switch (tag_type) {
#ifndef HAVE_OSX_ACLS
		case SMB_ACL_USER_OBJ:
			if (racl->user_obj == NO_ENTRY)
				racl->user_obj = access;
			else
				rprintf(FINFO, "unpack_smb_acl: warning: duplicate USER_OBJ entry ignored\n");
			continue;
		case SMB_ACL_GROUP_OBJ:
			if (racl->group_obj == NO_ENTRY)
				racl->group_obj = access;
			else
				rprintf(FINFO, "unpack_smb_acl: warning: duplicate GROUP_OBJ entry ignored\n");
			continue;
		case SMB_ACL_MASK:
			if (racl->mask_obj == NO_ENTRY)
				racl->mask_obj = access;
			else
				rprintf(FINFO, "unpack_smb_acl: warning: duplicate MASK entry ignored\n");
			continue;
		case SMB_ACL_OTHER:
			if (racl->other_obj == NO_ENTRY)
				racl->other_obj = access;
			else
				rprintf(FINFO, "unpack_smb_acl: warning: duplicate OTHER entry ignored\n");
			continue;
#endif
		case SMB_ACL_USER:
			access |= NAME_IS_USER;
			break;
		case SMB_ACL_GROUP:
			break;
		default:
			rprintf(FINFO, "unpack_smb_acl: warning: entry with unrecognized tag type ignored\n");
			continue;
		}
		ida = EXPAND_ITEM_LIST(&temp_ida_list, id_access, -10);
		ida->id = g_u_id;
		ida->access = access;
	}
	if (rc) {
		rsyserr(FERROR_XFER, errno, "unpack_smb_acl: %s()", errfun);
		rsync_acl_free(racl);
		return False;
	}

	/* Transfer the count id_access items out of the temp_ida_list
	 * into the names ida_entries list in racl. */
	if (temp_ida_list.count) {
#ifdef SMB_ACL_NEED_SORT
		if (temp_ida_list.count > 1) {
			qsort(temp_ida_list.items, temp_ida_list.count,
			      sizeof (id_access), id_access_sorter);
		}
#endif
		if (!(racl->names.idas = new_array(id_access, temp_ida_list.count)))
			out_of_memory("unpack_smb_acl");
		memcpy(racl->names.idas, temp_ida_list.items,
		       temp_ida_list.count * sizeof (id_access));
	} else
		racl->names.idas = NULL;

	racl->names.count = temp_ida_list.count;

	/* Truncate the temporary list now that its idas have been saved. */
	temp_ida_list.count = 0;

#ifdef ACLS_NEED_MASK
	if (!racl->names.count && racl->mask_obj != NO_ENTRY) {
		/* Throw away a superfluous mask, but mask off the
		 * group perms with it first. */
		racl->group_obj &= racl->mask_obj;
		racl->mask_obj = NO_ENTRY;
	}
#endif

	return True;
}

/* Synactic sugar for system calls */

#define CALL_OR_ERROR(func,args,str) \
	do { \
		if (func args) { \
			errfun = str; \
			goto error_exit; \
		} \
	} while (0)

#define COE(func,args) CALL_OR_ERROR(func,args,#func)
#define COE2(func,args) CALL_OR_ERROR(func,args,NULL)

#ifndef HAVE_OSX_ACLS
/* Store the permissions in the system ACL entry. */
static int store_access_in_entry(uint32 access, SMB_ACL_ENTRY_T entry)
{
	if (sys_acl_set_access_bits(entry, access)) {
		rsyserr(FERROR_XFER, errno, "store_access_in_entry sys_acl_set_access_bits()");
		return -1;
	}
	return 0;
}
#endif

/* Pack rsync ACL -> system ACL verbatim.  Return whether we succeeded. */
static BOOL pack_smb_acl(SMB_ACL_T *smb_acl, const rsync_acl *racl)
{
#ifdef ACLS_NEED_MASK
	uchar mask_bits;
#endif
	size_t count;
	id_access *ida;
	const char *errfun = NULL;
	SMB_ACL_ENTRY_T entry;

	if (!(*smb_acl = sys_acl_init(calc_sacl_entries(racl)))) {
		rsyserr(FERROR_XFER, errno, "pack_smb_acl: sys_acl_init()");
		return False;
	}

#ifndef HAVE_OSX_ACLS
	COE( sys_acl_create_entry,(smb_acl, &entry) );
	COE( sys_acl_set_info,(entry, SMB_ACL_USER_OBJ, racl->user_obj & ~NO_ENTRY, 0) );
#endif

	for (ida = racl->names.idas, count = racl->names.count; count; ida++, count--) {
#ifdef SMB_ACL_NEED_SORT
		if (!(ida->access & NAME_IS_USER))
			break;
#endif
		COE( sys_acl_create_entry,(smb_acl, &entry) );
		COE( sys_acl_set_info,
		    (entry,
		     ida->access & NAME_IS_USER ? SMB_ACL_USER : SMB_ACL_GROUP,
		     ida->access & ~NAME_IS_USER, ida->id) );
	}

#ifndef HAVE_OSX_ACLS
	COE( sys_acl_create_entry,(smb_acl, &entry) );
	COE( sys_acl_set_info,(entry, SMB_ACL_GROUP_OBJ, racl->group_obj & ~NO_ENTRY, 0) );

#ifdef SMB_ACL_NEED_SORT
	for ( ; count; ida++, count--) {
		COE( sys_acl_create_entry,(smb_acl, &entry) );
		COE( sys_acl_set_info,(entry, SMB_ACL_GROUP, ida->access, ida->id) );
	}
#endif

#ifdef ACLS_NEED_MASK
	mask_bits = racl->mask_obj == NO_ENTRY ? racl->group_obj & ~NO_ENTRY : racl->mask_obj;
	COE( sys_acl_create_entry,(smb_acl, &entry) );
	COE( sys_acl_set_info,(entry, SMB_ACL_MASK, mask_bits, NULL) );
#else
	if (racl->mask_obj != NO_ENTRY) {
		COE( sys_acl_create_entry,(smb_acl, &entry) );
		COE( sys_acl_set_info,(entry, SMB_ACL_MASK, racl->mask_obj, 0) );
	}
#endif

	COE( sys_acl_create_entry,(smb_acl, &entry) );
	COE( sys_acl_set_info,(entry, SMB_ACL_OTHER, racl->other_obj & ~NO_ENTRY, 0) );
#endif

#ifdef DEBUG
	if (sys_acl_valid(*smb_acl) < 0)
		rprintf(FERROR_XFER, "pack_smb_acl: warning: system says the ACL I packed is invalid\n");
#endif

	return True;

  error_exit:
	if (errfun) {
		rsyserr(FERROR_XFER, errno, "pack_smb_acl %s()", errfun);
	}
	sys_acl_free_acl(*smb_acl);
	return False;
}

static int find_matching_rsync_acl(const rsync_acl *racl, SMB_ACL_TYPE_T type,
				   const item_list *racl_list)
{
	static int access_match = -1, default_match = -1;
	int *match = type == SMB_ACL_TYPE_ACCESS ? &access_match : &default_match;
	size_t count = racl_list->count;

	/* If this is the first time through or we didn't match the last
	 * time, then start at the end of the list, which should be the
	 * best place to start hunting. */
	if (*match == -1)
		*match = racl_list->count - 1;
	while (count--) {
		rsync_acl *base = racl_list->items;
		if (rsync_acl_equal(base + *match, racl))
			return *match;
		if (!(*match)--)
			*match = racl_list->count - 1;
	}

	*match = -1;
	return *match;
}

static int get_rsync_acl(const char *fname, rsync_acl *racl,
			 SMB_ACL_TYPE_T type, mode_t mode)
{
	SMB_ACL_T sacl;

#ifdef SUPPORT_XATTRS
	/* --fake-super support: load ACLs from an xattr. */
	if (am_root < 0) {
		char *buf;
		size_t len;
		int cnt;

		if ((buf = get_xattr_acl(fname, type == SMB_ACL_TYPE_ACCESS, &len)) == NULL)
			return 0;
		cnt = (len - 4*4) / (4+4);
		if (len < 4*4 || len != (size_t)cnt*(4+4) + 4*4) {
			free(buf);
			return -1;
		}

		racl->user_obj = IVAL(buf, 0);
		racl->group_obj = IVAL(buf, 4);
		racl->mask_obj = IVAL(buf, 8);
		racl->other_obj = IVAL(buf, 12);

		if (cnt) {
			char *bp = buf + 4*4;
			id_access *ida;
			if (!(ida = racl->names.idas = new_array(id_access, cnt)))
				out_of_memory("get_rsync_acl");
			racl->names.count = cnt;
			for ( ; cnt--; ida++, bp += 4+4) {
				ida->id = IVAL(bp, 0);
				ida->access = IVAL(bp, 4);
			}
		}
		free(buf);
		return 0;
	}
#endif

	if ((sacl = sys_acl_get_file(fname, type)) != 0) {
		BOOL ok = unpack_smb_acl(sacl, racl);

		sys_acl_free_acl(sacl);
		if (!ok) {
			return -1;
		}
	} else if (no_acl_syscall_error(errno)) {
		/* ACLs are not supported, so pretend we have a basic ACL. */
		if (type == SMB_ACL_TYPE_ACCESS)
			rsync_acl_fake_perms(racl, mode);
	} else {
		rsyserr(FERROR_XFER, errno, "get_acl: sys_acl_get_file(%s, %s)",
			fname, str_acl_type(type));
		return -1;
	}

	return 0;
}

/* Return the Access Control List for the given filename. */
int get_acl(const char *fname, stat_x *sxp)
{
	sxp->acc_acl = create_racl();
	if (get_rsync_acl(fname, sxp->acc_acl, SMB_ACL_TYPE_ACCESS,
			  sxp->st.st_mode) < 0) {
		free_acl(sxp);
		return -1;
	}

	if (S_ISDIR(sxp->st.st_mode)) {
		sxp->def_acl = create_racl();
		if (get_rsync_acl(fname, sxp->def_acl, SMB_ACL_TYPE_DEFAULT,