diff options
Diffstat (limited to 'fs/smb/client/namespace.c')
| -rw-r--r-- | fs/smb/client/namespace.c | 249 |
1 files changed, 249 insertions, 0 deletions
diff --git a/fs/smb/client/namespace.c b/fs/smb/client/namespace.c new file mode 100644 index 000000000000..c8f5ed8a69f1 --- /dev/null +++ b/fs/smb/client/namespace.c @@ -0,0 +1,249 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Contains mounting routines used for handling traversal via SMB junctions. + * + * Copyright (c) 2007 Igor Mammedov + * Copyright (C) International Business Machines Corp., 2008 + * Author(s): Igor Mammedov ([email protected]) + * Steve French ([email protected]) + * Copyright (c) 2023 Paulo Alcantara <[email protected]> + */ + +#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 "cifs_debug.h" +#include "fs_context.h" + +static LIST_HEAD(cifs_automount_list); + +static void cifs_expire_automounts(struct work_struct *work); +static DECLARE_DELAYED_WORK(cifs_automount_task, + cifs_expire_automounts); +static int cifs_mountpoint_expiry_timeout = 500 * HZ; + +static void cifs_expire_automounts(struct work_struct *work) +{ + struct list_head *list = &cifs_automount_list; + + mark_mounts_for_expiry(list); + if (!list_empty(list)) + schedule_delayed_work(&cifs_automount_task, + cifs_mountpoint_expiry_timeout); +} + +void cifs_release_automount_timer(void) +{ + if (WARN_ON(!list_empty(&cifs_automount_list))) + return; + cancel_delayed_work_sync(&cifs_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; +} + +/* Return full path out of a dentry set for automount */ +static char *automount_fullpath(struct dentry *dentry, void *page) +{ + struct cifs_sb_info *cifs_sb = CIFS_SB(dentry->d_sb); + struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb); + size_t len; + char *s; + + spin_lock(&tcon->tc_lock); + if (!tcon->origin_fullpath) { + spin_unlock(&tcon->tc_lock); + return build_path_from_dentry_optional_prefix(dentry, + page, + true); + } + spin_unlock(&tcon->tc_lock); + + s = dentry_path_raw(dentry, page, PATH_MAX); + if (IS_ERR(s)) + return s; + /* for root, we want "" */ + if (!s[1]) + s++; + + spin_lock(&tcon->tc_lock); + len = strlen(tcon->origin_fullpath); + if (s < (char *)page + len) { + spin_unlock(&tcon->tc_lock); + return ERR_PTR(-ENAMETOOLONG); + } + + s -= len; + memcpy(s, tcon->origin_fullpath, len); + spin_unlock(&tcon->tc_lock); + convert_delimiter(s, '/'); + + return s; +} + +/* + * Create a vfsmount that we can automount + */ +static struct vfsmount *cifs_do_automount(struct path *path) +{ + int rc; + struct dentry *mntpt = path->dentry; + struct fs_context *fc; + 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); + + cur_ctx = CIFS_SB(mntpt->d_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 = automount_fullpath(mntpt, page); + if (IS_ERR(full_path)) { + mnt = ERR_CAST(full_path); + goto out; + } + + tmp = *cur_ctx; + tmp.source = NULL; + 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 = smb3_parse_devname(full_path, ctx); + if (rc) { + mnt = ERR_PTR(rc); + goto out; + } + + ctx->source = smb3_fs_context_fullpath(ctx, '/'); + if (IS_ERR(ctx->source)) { + mnt = ERR_CAST(ctx->source); + ctx->source = NULL; + goto out; + } + cifs_dbg(FYI, "%s: ctx: source=%s UNC=%s prepath=%s\n", + __func__, ctx->source, ctx->UNC, ctx->prepath); + + mnt = fc_mount(fc); +out: + put_fs_context(fc); + free_dentry_path(page); + return mnt; +} + +/* + * Attempt to automount the referral + */ +struct vfsmount *cifs_d_automount(struct path *path) +{ + struct vfsmount *newmnt; + + cifs_dbg(FYI, "%s: %pd\n", __func__, path->dentry); + + newmnt = cifs_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_automount_list); + schedule_delayed_work(&cifs_automount_task, + cifs_mountpoint_expiry_timeout); + cifs_dbg(FYI, "leaving %s [ok]\n" , __func__); + return newmnt; +} + +const struct inode_operations cifs_namespace_inode_operations = { +}; |