diff options
Diffstat (limited to 'fs/smb/client/cifs_dfs_ref.c')
| -rw-r--r-- | fs/smb/client/cifs_dfs_ref.c | 230 |
1 files changed, 230 insertions, 0 deletions
diff --git a/fs/smb/client/cifs_dfs_ref.c b/fs/smb/client/cifs_dfs_ref.c new file mode 100644 index 000000000000..0329a907bdfe --- /dev/null +++ b/fs/smb/client/cifs_dfs_ref.c @@ -0,0 +1,230 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Contains the CIFS DFS referral mounting routines used for handling + * traversal via DFS junction point + * + * Copyright (c) 2007 Igor Mammedov + * Copyright (C) International Business Machines Corp., 2008 + * Author(s): Igor Mammedov (niallain@gmail.com) + * Steve French (sfrench@us.ibm.com) + */ + +#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 <linux/inet.h> +#include "cifsglob.h" +#include "cifsproto.h" +#include "cifsfs.h" +#include "dns_resolve.h" +#include "cifs_debug.h" +#include "dfs.h" +#include "fs_context.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_build_devname - build a devicename from a UNC and optional prepath + * @nodename: pointer to UNC string + * @prepath: pointer to prefixpath (or NULL if there isn't one) + * + * Build a new cifs devicename after chasing a DFS referral. Allocate a buffer + * big enough to hold the final thing. Copy the UNC from the nodename, and + * concatenate the prepath onto the end of it if there is one. + * + * Returns pointer to the built string, or a ERR_PTR. Caller is responsible + * for freeing the returned string. + */ +char * +cifs_build_devname(char *nodename, const char *prepath) +{ + size_t pplen; + size_t unclen; + char *dev; + char *pos; + + /* skip over any preceding delimiters */ + nodename += strspn(nodename, "\\"); + if (!*nodename) + return ERR_PTR(-EINVAL); + + /* get length of UNC and set pos to last char */ + unclen = strlen(nodename); + pos = nodename + unclen - 1; + + /* trim off any trailing delimiters */ + while (*pos == '\\') { + --pos; + --unclen; + } + + /* allocate a buffer: + * +2 for preceding "//" + * +1 for delimiter between UNC and prepath + * +1 for trailing NULL + */ + pplen = prepath ? strlen(prepath) : 0; + dev = kmalloc(2 + unclen + 1 + pplen + 1, GFP_KERNEL); + if (!dev) + return ERR_PTR(-ENOMEM); + + pos = dev; + /* add the initial "//" */ + *pos = '/'; + ++pos; + *pos = '/'; + ++pos; + + /* copy in the UNC portion from referral */ + memcpy(pos, nodename, unclen); + pos += unclen; + + /* copy the prefixpath remainder (if there is one) */ + if (pplen) { + *pos = '/'; + ++pos; + memcpy(pos, prepath, pplen); + pos += pplen; + } + + /* NULL terminator */ + *pos = '\0'; + + convert_delimiter(dev, '/'); + return dev; +} + +static int set_dest_addr(struct smb3_fs_context *ctx, const char *full_path) +{ + struct sockaddr *addr = (struct sockaddr *)&ctx->dstaddr; + int rc; + + rc = dns_resolve_server_name_to_ip(full_path, addr, NULL); + if (!rc) + cifs_set_port(addr, ctx->port); + return rc; +} + +/* + * Create a vfsmount that we can automount + */ +static struct vfsmount *cifs_dfs_do_automount(struct path *path) +{ + int rc; + struct dentry *mntpt = path->dentry; + struct fs_context *fc; + struct cifs_sb_info *cifs_sb; + void *page = NULL; + struct smb3_fs_context *ctx, *cur_ctx; + struct smb3_fs_context tmp; + char *full_path; + struct vfsmount *mnt; + + if (IS_ROOT(mntpt)) + return ERR_PTR(-ESTALE); + + /* + * 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. + */ + cifs_sb = CIFS_SB(mntpt->d_sb); + if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS) + return ERR_PTR(-EREMOTE); + + cur_ctx = cifs_sb->ctx; + + fc = fs_context_for_submount(path->mnt->mnt_sb->s_type, mntpt); + if (IS_ERR(fc)) + return ERR_CAST(fc); + + ctx = smb3_fc2context(fc); + + page = alloc_dentry_path(); + full_path = dfs_get_automount_devname(mntpt, page); + if (IS_ERR(full_path)) { + mnt = ERR_CAST(full_path); + goto out; + } + cifs_dbg(FYI, "%s: full_path: %s\n", __func__, full_path); + + tmp = *cur_ctx; + tmp.source = full_path; + tmp.leaf_fullpath = NULL; + tmp.UNC = tmp.prepath = NULL; + tmp.dfs_root_ses = NULL; + + rc = smb3_fs_context_dup(ctx, &tmp); + if (rc) { + mnt = ERR_PTR(rc); + goto out; + } + + rc = set_dest_addr(ctx, full_path); + if (rc) { + mnt = ERR_PTR(rc); + goto out; + } + + rc = smb3_parse_devname(full_path, ctx); + if (!rc) + mnt = fc_mount(fc); + else + mnt = ERR_PTR(rc); + +out: + put_fs_context(fc); + free_dentry_path(page); + return mnt; +} + +/* + * Attempt to automount the referral + */ +struct vfsmount *cifs_dfs_d_automount(struct path *path) +{ + struct vfsmount *newmnt; + + cifs_dbg(FYI, "%s: %pd\n", __func__, path->dentry); + + newmnt = cifs_dfs_do_automount(path); + if (IS_ERR(newmnt)) { + cifs_dbg(FYI, "leaving %s [automount failed]\n" , __func__); + return newmnt; + } + + mntget(newmnt); /* prevent immediate expiration */ + mnt_set_expiry(newmnt, &cifs_dfs_automount_list); + schedule_delayed_work(&cifs_dfs_automount_task, + cifs_dfs_mountpoint_expiry_timeout); + cifs_dbg(FYI, "leaving %s [ok]\n" , __func__); + return newmnt; +} + +const struct inode_operations cifs_dfs_referral_inode_operations = { +}; |