cifs_dfs_ref.rar_The Point

/* * Contains the CIFS DFS referral mounting routines used for handling * traversal via DFS junction point * */ #include <linux/dcache.h> #include <linux/mount.h> #include <linux/namei.h> #include <linux/slab.h> #include <linux/vfs.h> #include <linux/fs.h> #include "cifsglob.h" #include "cifsproto.h" #include "cifsfs.h" #include "dns_resolve.h" #include "cifs_debug.h" static LIST_HEAD(cifs_dfs_automount_list); static void cifs_dfs_expire_automounts(struct work_struct *work); static DECLARE_DELAYED_WORK(cifs_dfs_automount_task, cifs_dfs_expire_automounts); static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ; static void cifs_dfs_expire_automounts(struct work_struct *work) { struct list_head *list = &cifs_dfs_automount_list; mark_mounts_for_expiry(list); if (!list_empty(list)) schedule_delayed_work(&cifs_dfs_automount_task, cifs_dfs_mountpoint_expiry_timeout); } void cifs_dfs_release_automount_timer(void) { BUG_ON(!list_empty(&cifs_dfs_automount_list)); cancel_delayed_work_sync(&cifs_dfs_automount_task); } /** * cifs_get_share_name - extracts share name from UNC * @node_name: pointer to UNC string * * Extracts sharename form full UNC. * i.e. strips from UNC trailing path that is not part of share * name and fixup missing '\' in the beginning of DFS node refferal * if necessary. * Returns pointer to share name on success or ERR_PTR on error. * Caller is responsible for freeing returned string. */ static char *cifs_get_share_name(const char *node_name) { int len; char *UNC; char *pSep; len = strlen(node_name); UNC = kmalloc(len+2 /*for term null and additional \ if it's missed */, GFP_KERNEL); if (!UNC) return ERR_PTR(-ENOMEM); /* get share name and server name */ if (node_name[1] != '\\') { UNC[0] = '\\'; strncpy(UNC+1, node_name, len); len++; UNC[len] = 0; } else { strncpy(UNC, node_name, len); UNC[len] = 0; } /* find server name end */ pSep = memchr(UNC+2, '\\', len-2); if (!pSep) { cERROR(1, "%s: no server name end in node name: %s", __func__, node_name); kfree(UNC); return ERR_PTR(-EINVAL); } /* find sharename end */ pSep++; pSep = memchr(UNC+(pSep-UNC), '\\', len-(pSep-UNC)); if (pSep) { /* trim path up to sharename end * now we have share name in UNC */ *pSep = 0; } return UNC; } /** * cifs_compose_mount_options - creates mount options for refferral * @sb_mountdata: parent/root DFS mount options (template) * @fullpath: full path in UNC format * @ref: server's referral * @devname: pointer for saving device name * * creates mount options for submount based on template options sb_mountdata * and replacing unc,ip,prefixpath options with ones we've got form ref_unc. * * Returns: pointer to new mount options or ERR_PTR. * Caller is responcible for freeing retunrned value if it is not error. */ char *cifs_compose_mount_options(const char *sb_mountdata, const char *fullpath, const struct dfs_info3_param *ref, char **devname) { int rc; char *mountdata = NULL; int md_len; char *tkn_e; char *srvIP = NULL; char sep = ','; int off, noff; if (sb_mountdata == NULL) return ERR_PTR(-EINVAL); *devname = cifs_get_share_name(ref->node_name); if (IS_ERR(*devname)) { rc = PTR_ERR(*devname); *devname = NULL; goto compose_mount_options_err; } rc = dns_resolve_server_name_to_ip(*devname, &srvIP); if (rc < 0) { cERROR(1, "%s: Failed to resolve server part of %s to IP: %d", __func__, *devname, rc); goto compose_mount_options_err; } /* md_len = strlen(...) + 12 for 'sep+prefixpath=' * assuming that we have 'unc=' and 'ip=' in * the original sb_mountdata */ md_len = strlen(sb_mountdata) + rc + strlen(ref->node_name) + 12; mountdata = kzalloc(md_len+1, GFP_KERNEL); if (mountdata == NULL) { rc = -ENOMEM; goto compose_mount_options_err; } /* copy all options except of unc,ip,prefixpath */ off = 0; if (strncmp(sb_mountdata, "sep=", 4) == 0) { sep = sb_mountdata[4]; strncpy(mountdata, sb_mountdata, 5); off += 5; } do { tkn_e = strchr(sb_mountdata + off, sep); if (tkn_e == NULL) noff = strlen(sb_mountdata + off); else noff = tkn_e - (sb_mountdata + off) + 1; if (strnicmp(sb_mountdata + off, "unc=", 4) == 0) { off += noff; continue; } if (strnicmp(sb_mountdata + off, "ip=", 3) == 0) { off += noff; continue; } if (strnicmp(sb_mountdata + off, "prefixpath=", 11) == 0) { off += noff; continue; } strncat(mountdata, sb_mountdata + off, noff); off += noff; } while (tkn_e); strcat(mountdata, sb_mountdata + off); mountdata[md_len] = '\0'; /* copy new IP and ref share name */ if (mountdata[strlen(mountdata) - 1] != sep) strncat(mountdata, &sep, 1); strcat(mountdata, "ip="); strcat(mountdata, srvIP); strncat(mountdata, &sep, 1); strcat(mountdata, "unc="); strcat(mountdata, *devname); /* find & copy prefixpath */ tkn_e = strchr(ref->node_name + 2, '\\'); if (tkn_e == NULL) { /* invalid unc, missing share name*/ rc = -EINVAL; goto compose_mount_options_err; } tkn_e = strchr(tkn_e + 1, '\\'); if (tkn_e || (strlen(fullpath) - ref->path_consumed)) { strncat(mountdata, &sep, 1); strcat(mountdata, "prefixpath="); if (tkn_e) strcat(mountdata, tkn_e + 1); strcat(mountdata, fullpath + ref->path_consumed); } /*cFYI(1, "%s: parent mountdata: %s", __func__,sb_mountdata);*/ /*cFYI(1, "%s: submount mountdata: %s", __func__, mountdata );*/ compose_mount_options_out: kfree(srvIP); return mountdata; compose_mount_options_err: kfree(mountdata); mountdata = ERR_PTR(rc); goto compose_mount_options_out; } /** * cifs_dfs_do_refmount - mounts specified path using provided refferal * @cifs_sb: parent/root superblock * @fullpath: full path in UNC format * @ref: server's referral */ static struct vfsmount *cifs_dfs_do_refmount(struct cifs_sb_info *cifs_sb, const char *fullpath, const struct dfs_info3_param *ref) { struct vfsmount *mnt; char *mountdata; char *devname = NULL; /* strip first '\' from fullpath */ mountdata = cifs_compose_mount_options(cifs_sb->mountdata, fullpath + 1, ref, &devname); if (IS_ERR(mountdata)) return (struct vfsmount *)mountdata; mnt = vfs_kern_mount(&cifs_fs_type, 0, devname, mountdata); kfree(mountdata); kfree(devname); return mnt; } static void dump_referral(const struct dfs_info3_param *ref) { cFYI(1, "DFS: ref path: %s", ref->path_name); cFYI(1, "DFS: node path: %s", ref->node_name); cFYI(1, "DFS: fl: %hd, srv_type: %hd", ref->flags, ref->server_type); cFYI(1, "DFS: ref_flags: %hd, path_consumed: %hd", ref->ref_flag, ref->path_consumed); } /* * Create a vfsmount that we can automount */ static struct vfsmount *cifs_dfs_do_automount(struct dentry *mntpt) { struct dfs_info3_param *referrals = NULL; unsigned int num_referrals = 0; struct cifs_sb_info *cifs_sb; struct cifs_ses *ses; char *full_path; int xid, i; int rc; struct vfsmount *mnt; struct tcon_link *tlink; cFYI(1, "in %s", __func__); BUG_ON(IS_ROOT(mntpt)); /* * The MSDFS spec states that paths in DFS referral requests and * responses must be prefixed by a single '\' character instead of * the double backslashes usually used in the UNC. This function * gives us the latter, so we must adjust the result. */ mnt = ERR_PTR(-ENOMEM); full_path = build_path_from_dentry(mntpt); if (full_path == NULL) goto cdda_exit; cifs_sb = CIFS_SB(mntpt->d_inode->i_sb); tlink = cifs_sb_tlink(cifs_sb); if (IS_ERR(tlink)) { mnt = ERR_CAST(tlink); goto free_full_path; } ses = tlink_tcon(tlink)->ses; xid = GetXid(); rc = get_dfs_path(xid, ses, full_path + 1, cifs_sb->local_nls, &num_referrals, &referrals, cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MAP_SPECIAL_CHR); FreeXid(xid); cifs_put_tlink(tlink); mnt = ERR_PTR(-ENOENT); for (i = 0; i < num_referrals; i++) { int len; dump_referral(referrals + i); /* connect to a node */ len = strlen(referrals[i].node_n