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-rw-r--r--fs/smb/client/namespace.c262
1 files changed, 262 insertions, 0 deletions
diff --git a/fs/smb/client/namespace.c b/fs/smb/client/namespace.c
new file mode 100644
index 0000000000..a6968573b7
--- /dev/null
+++ b/fs/smb/client/namespace.c
@@ -0,0 +1,262 @@
+// 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 (niallain@gmail.com)
+ * Steve French (sfrench@us.ibm.com)
+ * Copyright (c) 2023 Paulo Alcantara <palcantara@suse.de>
+ */
+
+#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;
+}
+
+static bool is_dfs_mount(struct dentry *dentry)
+{
+ struct cifs_sb_info *cifs_sb = CIFS_SB(dentry->d_sb);
+ struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
+ bool ret;
+
+ spin_lock(&tcon->tc_lock);
+ ret = !!tcon->origin_fullpath;
+ spin_unlock(&tcon->tc_lock);
+ return ret;
+}
+
+/* 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;
+ }
+ ctx->dfs_automount = is_dfs_mount(mntpt);
+ cifs_dbg(FYI, "%s: ctx: source=%s UNC=%s prepath=%s dfs_automount=%d\n",
+ __func__, ctx->source, ctx->UNC, ctx->prepath, ctx->dfs_automount);
+
+ 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 = {
+};
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-23 23:06:04 +0000