linux-kernel - [resend PATCH v2 1/2] fuse: revalidate: move lookup into a separate function

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <82abdcba1e56dd3bc524bc3f2f44ae9c71f40fb7.1696043833.git.kjlx@templeofstupid.com>
Date:   Mon, 2 Oct 2023 08:24:38 -0700
From:   Krister Johansen <kjlx@...pleofstupid.com>
To:     Miklos Szeredi <miklos@...redi.hu>, linux-fsdevel@...r.kernel.org
Cc:     Miklos Szeredi <mszeredi@...hat.com>, linux-kernel@...r.kernel.org,
        German Maglione <gmaglione@...hat.com>,
        Greg Kurz <groug@...d.org>, Max Reitz <mreitz@...hat.com>,
        Bernd Schubert <bernd.schubert@...tmail.fm>
Subject: [resend PATCH v2 1/2] fuse: revalidate: move lookup into a separate
 function

Move the lookup parts of fuse_dentry_revalidate into a common function.
This function will be used elsewhere in a separate commit.  In the
meantime, the new function fuse_dentry_revalidate_lookup is responsible
for just the lookup and validation portions of the revalidate dance.
The fuse_dentry_revalidate function retains the responsibility for
invalidating and mutating any state associated with the origial
fuse_inode and dentry.

The rationale for this refactoring is to allow a lookup to be triggered
as part of creating a submount.  The submount code lives in another
module.  A subsequent commit will utilize the common function that is
created by this commit.

Signed-off-by: Krister Johansen <kjlx@...pleofstupid.com>
---
 fs/fuse/dir.c | 85 +++++++++++++++++++++++++++++++++++----------------
 1 file changed, 58 insertions(+), 27 deletions(-)

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index d707e6987da9..5e01946d7531 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -183,6 +183,57 @@ static void fuse_lookup_init(struct fuse_conn *fc, struct fuse_args *args,
 	args->out_args[0].value = outarg;
 }
 
+static int fuse_dentry_revalidate_lookup(struct fuse_mount *fm,
+					 struct dentry *entry,
+					 struct inode *inode,
+					 struct fuse_entry_out *outarg,
+					 bool *lookedup)
+{
+	struct dentry *parent;
+	struct fuse_forget_link *forget;
+	FUSE_ARGS(args);
+	int ret;
+
+	forget = fuse_alloc_forget();
+	ret = -ENOMEM;
+	if (!forget)
+		goto out;
+
+	parent = dget_parent(entry);
+	fuse_lookup_init(fm->fc, &args, get_node_id(d_inode(parent)),
+			 &entry->d_name, outarg);
+	ret = fuse_simple_request(fm, &args);
+	dput(parent);
+
+	/* Zero nodeid is same as -ENOENT */
+	if (!ret && !outarg->nodeid)
+		ret = -ENOENT;
+	if (!ret) {
+		if (outarg->nodeid != get_node_id(inode) ||
+		    (bool) IS_AUTOMOUNT(inode) != (bool) (outarg->attr.flags & FUSE_ATTR_SUBMOUNT)) {
+			fuse_queue_forget(fm->fc, forget,
+					  outarg->nodeid, 1);
+			goto invalid;
+		}
+		*lookedup = true;
+	}
+	kfree(forget);
+	if (ret == -ENOMEM || ret == -EINTR)
+		goto out;
+	if (ret || fuse_invalid_attr(&outarg->attr) ||
+	    fuse_stale_inode(inode, outarg->generation, &outarg->attr)) {
+		goto invalid;
+	}
+
+	ret = 1;
+out:
+	return ret;
+
+invalid:
+	ret = 0;
+	goto out;
+}
+
 /*
  * Check whether the dentry is still valid
  *
@@ -206,9 +257,8 @@ static int fuse_dentry_revalidate(struct dentry *entry, unsigned int flags)
 	else if (time_before64(fuse_dentry_time(entry), get_jiffies_64()) ||
 		 (flags & (LOOKUP_EXCL | LOOKUP_REVAL | LOOKUP_RENAME_TARGET))) {
 		struct fuse_entry_out outarg;
-		FUSE_ARGS(args);
-		struct fuse_forget_link *forget;
 		u64 attr_version;
+		bool lookedup = false;
 
 		/* For negative dentries, always do a fresh lookup */
 		if (!inode)
@@ -220,38 +270,19 @@ static int fuse_dentry_revalidate(struct dentry *entry, unsigned int flags)
 
 		fm = get_fuse_mount(inode);
 
-		forget = fuse_alloc_forget();
-		ret = -ENOMEM;
-		if (!forget)
-			goto out;
-
 		attr_version = fuse_get_attr_version(fm->fc);
 
-		parent = dget_parent(entry);
-		fuse_lookup_init(fm->fc, &args, get_node_id(d_inode(parent)),
-				 &entry->d_name, &outarg);
-		ret = fuse_simple_request(fm, &args);
-		dput(parent);
-		/* Zero nodeid is same as -ENOENT */
-		if (!ret && !outarg.nodeid)
-			ret = -ENOENT;
-		if (!ret) {
+		ret = fuse_dentry_revalidate_lookup(fm, entry, inode, &outarg,
+						    &lookedup);
+		if (ret == -ENOMEM || ret == -EINTR)
+			goto out;
+		if (lookedup) {
 			fi = get_fuse_inode(inode);
-			if (outarg.nodeid != get_node_id(inode) ||
-			    (bool) IS_AUTOMOUNT(inode) != (bool) (outarg.attr.flags & FUSE_ATTR_SUBMOUNT)) {
-				fuse_queue_forget(fm->fc, forget,
-						  outarg.nodeid, 1);
-				goto invalid;
-			}
 			spin_lock(&fi->lock);
 			fi->nlookup++;
 			spin_unlock(&fi->lock);
 		}
-		kfree(forget);
-		if (ret == -ENOMEM || ret == -EINTR)
-			goto out;
-		if (ret || fuse_invalid_attr(&outarg.attr) ||
-		    fuse_stale_inode(inode, outarg.generation, &outarg.attr))
+		if (ret <= 0)
 			goto invalid;
 
 		forget_all_cached_acls(inode);
-- 
2.25.1