uidlist.c

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/*
   Copyright (C) Andrew Tridgell 1996
   Copyright (C) Paul Mackerras 1996

   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 2 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, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

/* handle the mapping of uid/gid and user/group names between systems.
   If the source username/group does not exist on the target then use
   the numeric IDs. Never do any mapping for uid=0 or gid=0 as these
   are special.
*/

#include "rsync.h"

#ifdef HAVE_GETGROUPS
# ifndef GETGROUPS_T
#  define GETGROUPS_T gid_t
# endif
#endif

extern int verbose;
extern int preserve_uid;
extern int preserve_gid;
extern int preserve_acls;
extern int numeric_ids;
extern int am_root;

struct idlist {
        struct idlist *next;
        int id, id2;
        char *name;
};

static struct idlist *uidlist;
static struct idlist *gidlist;

static struct idlist *add_to_list(struct idlist **root, int id, char *name,
                                  int id2)
{
        struct idlist *node = new(struct idlist);
        if (!node)
                out_of_memory("add_to_list");
        node->next = *root;
        node->name = name;
        node->id = id;
        node->id2 = id2;
        *root = node;
        return node;
}

/* turn a uid into a user name */
static char *uid_to_name(uid_t uid)
{
        struct passwd *pass = getpwuid(uid);
        if (pass)
                return strdup(pass->pw_name);
        return NULL;
}

/* turn a gid into a group name */
static char *gid_to_name(gid_t gid)
{
        struct group *grp = getgrgid(gid);
        if (grp)
                return strdup(grp->gr_name);
        return NULL;
}

static int map_uid(int id, char *name)
{
        uid_t uid;
        if (id != 0 && name_to_uid(name, &uid))
                return uid;
        return id;
}

static int map_gid(int id, char *name)
{
        gid_t gid;
        if (id != 0 && name_to_gid(name, &gid))
                return gid;
        return id;
}

static int is_in_group(gid_t gid)
{
#ifdef HAVE_GETGROUPS
        static gid_t last_in = GID_NONE, last_out;
        static int ngroups = -2;
        static GETGROUPS_T *gidset;
        int n;

        if (gid == last_in)
                return last_out;
        if (ngroups < -1) {
                gid_t mygid = MY_GID();
                if ((ngroups = getgroups(0, NULL)) < 0)
                        ngroups = 0;
                gidset = new_array(GETGROUPS_T, ngroups+1);
                if (!gidset)
                        out_of_memory("is_in_group");
                if (ngroups > 0)
                        ngroups = getgroups(ngroups, gidset);
                /* The default gid might not be in the list on some systems. */
                for (n = 0; n < ngroups; n++) {
                        if (gidset[n] == mygid)
                                break;
                }
                if (n == ngroups)
                        gidset[ngroups++] = mygid;
                if (verbose > 3) {
                        int pos;
                        char *gidbuf = new_array(char, ngroups*21+32);
                        if (!gidbuf)
                                out_of_memory("is_in_group");
                        sprintf(gidbuf, "process has %d gid%s: ",
                            ngroups, ngroups == 1? "" : "s");
                        pos = strlen(gidbuf);
                        for (n = 0; n < ngroups; n++) {
                                sprintf(gidbuf+pos, " %d", (int)gidset[n]);
                                pos += strlen(gidbuf+pos);
                        }
                        rprintf(FINFO, "%s\n", gidbuf);
                        free(gidbuf);
                }
        }

        last_in = gid;
        for (n = 0; n < ngroups; n++) {
                if (gidset[n] == gid)
                        return last_out = 1;
        }
        return last_out = 0;

#else
        static gid_t mygid = GID_NONE;
        if (mygid == GID_NONE) {
                mygid = MY_GID();
                if (verbose > 3)
                        rprintf(FINFO, "process has gid %d\n", (int)mygid);
        }
        return gid == mygid;
#endif
}

/* Add a uid to the list of uids.  Only called on receiving side. */
static struct idlist *recv_add_uid(int id, char *name)
{
        int id2 = name ? map_uid(id, name) : id;
        struct idlist *node;

        node = add_to_list(&uidlist, id, name, id2);

        if (verbose > 3) {
                rprintf(FINFO, "uid %d(%s) maps to %d\n",
                    id, name ? name : "", id2);
        }

        return node;
}

/* Add a gid to the list of gids.  Only called on receiving side. */
static struct idlist *recv_add_gid(int id, char *name)
{
        int id2 = name ? map_gid(id, name) : id;
        struct idlist *node;

        if (!am_root && !is_in_group(id2))
                id2 = GID_NONE;
        node = add_to_list(&gidlist, id, name, id2);

        if (verbose > 3) {
                rprintf(FINFO, "gid %d(%s) maps to %d\n",
                    id, name ? name : "", id2);
        }

        return node;
}

/* this function is a definate candidate for a faster algorithm */
static uid_t match_uid(uid_t uid)
{
        static uid_t last_in, last_out;
        struct idlist *list;

        if (uid == 0)
                return 0;

        if (uid == last_in)
                return last_out;

        last_in = uid;

        for (list = uidlist; list; list = list->next) {
                if (list->id == (int)uid)
                        return last_out = (uid_t)list->id2;
        }

        return last_out = uid;
}

static gid_t match_gid(gid_t gid)
{
        static gid_t last_in = GID_NONE, last_out = GID_NONE;
        struct idlist *list;

        if (gid == GID_NONE)
                return GID_NONE;

        if (gid == last_in)
                return last_out;

        last_in = gid;

        for (list = gidlist; list; list = list->next) {
                if (list->id == (int)gid)
                        return last_out = (gid_t)list->id2;
        }

        list = recv_add_gid(gid, NULL);
        return last_out = list->id2;
}

/* Add a uid to the list of uids.  Only called on sending side. */
void add_uid(uid_t uid)
{
        struct idlist *list;

        if (uid == 0)   /* don't map root */
                return;

        for (list = uidlist; list; list = list->next) {
                if (list->id == (int)uid)
                        return;
        }

        add_to_list(&uidlist, (int)uid, uid_to_name(uid), 0);
}

/* Add a gid to the list of gids.  Only called on sending side. */
void add_gid(gid_t gid)
{
        struct idlist *list;

        if (gid == 0)   /* don't map root */
                return;

        for (list = gidlist; list; list = list->next) {
                if (list->id == (int)gid)
                        return;
        }

        add_to_list(&gidlist, (int)gid, gid_to_name(gid), 0);
}


/* send a complete uid/gid mapping to the peer */
void send_uid_list(int f)
{
        struct idlist *list;

        if (numeric_ids)
                return;

        if (preserve_uid || preserve_acls) {
                int len;
                /* we send sequences of uid/byte-length/name */
                for (list = uidlist; list; list = list->next) {
                        if (!list->name)
                                continue;
                        len = strlen(list->name);
                        write_int(f, list->id);
                        write_byte(f, len);
                        write_buf(f, list->name, len);
                }

                /* terminate the uid list with a 0 uid. We explicitly exclude
                 * 0 from the list */
                write_int(f, 0);
        }

        if (preserve_gid || preserve_acls) {
                int len;
                for (list = gidlist; list; list = list->next) {
                        if (!list->name)
                                continue;
                        len = strlen(list->name);
                        write_int(f, list->id);
                        write_byte(f, len);
                        write_buf(f, list->name, len);
                }
                write_int(f, 0);
        }
}

/* recv a complete uid/gid mapping from the peer and map the uid/gid
 * in the file list to local names */
void recv_uid_list(int f, struct file_list *flist)
{
        int id, i;
        char *name;

        if ((preserve_uid || preserve_acls) && !numeric_ids) {
                /* read the uid list */
                while ((id = read_int(f)) != 0) {
                        int len = read_byte(f);
                        name = new_array(char, len+1);
                        if (!name)
                                out_of_memory("recv_uid_list");
                        read_sbuf(f, name, len);
                        recv_add_uid(id, name); /* node keeps name's memory */
                }
        }

        if ((preserve_gid || preserve_acls) && !numeric_ids) {
                /* read the gid list */
                while ((id = read_int(f)) != 0) {
                        int len = read_byte(f);
                        name = new_array(char, len+1);
                        if (!name)
                                out_of_memory("recv_uid_list");
                        read_sbuf(f, name, len);
                        recv_add_gid(id, name); /* node keeps name's memory */
                }
        }

#ifdef SUPPORT_ACLS
        if (preserve_acls && !numeric_ids) {
                id_t *id;
                while ((id = next_acl_uid(flist)) != NULL)
                        *id = match_uid(*id);
                while ((id = next_acl_gid(flist)) != NULL)
                        *id = match_gid(*id);
        }
#endif

        /* Now convert all the uids/gids from sender values to our values. */
        if (am_root && preserve_uid && !numeric_ids) {
                for (i = 0; i < flist->count; i++)
                        flist->files[i]->uid = match_uid(flist->files[i]->uid);
        }
        if (preserve_gid && (!am_root || !numeric_ids)) {
                for (i = 0; i < flist->count; i++)
                        flist->files[i]->gid = match_gid(flist->files[i]->gid);
        }
}

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