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From:   Eric Biggers <ebiggers@kernel.org>
To:     linux-fscrypt@vger.kernel.org
Cc:     linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net,
        linux-mtd@lists.infradead.org, linux-fsdevel@vger.kernel.org,
        stable@vger.kernel.org
Subject: [PATCH 3/5] f2fs: report correct st_size for encrypted symlinks
Date:   Thu,  1 Jul 2021 23:53:48 -0700
Message-Id: <20210702065350.209646-4-ebiggers@kernel.org>
In-Reply-To: <20210702065350.209646-1-ebiggers@kernel.org>
References: <20210702065350.209646-1-ebiggers@kernel.org>
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From: Eric Biggers <ebiggers@google.com>

The stat() family of syscalls report the wrong size for encrypted
symlinks, which has caused breakage in several userspace programs.

Fix this by calling fscrypt_symlink_getattr() after f2fs_getattr() for
encrypted symlinks.  This function computes the correct size by reading
and decrypting the symlink target (if it's not already cached).

For more details, see the commit which added fscrypt_symlink_getattr().

Fixes: cbaf042a3cc6 ("f2fs crypto: add symlink encryption")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/f2fs/namei.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
index a9cd9cf97229..e2d540ae2293 100644
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -1305,9 +1305,19 @@ static const char *f2fs_encrypted_get_link(struct dentry *dentry,
 	return target;
 }
 
+static int f2fs_encrypted_symlink_getattr(struct user_namespace *mnt_userns,
+					  const struct path *path,
+					  struct kstat *stat, u32 request_mask,
+					  unsigned int query_flags)
+{
+	f2fs_getattr(mnt_userns, path, stat, request_mask, query_flags);
+
+	return fscrypt_symlink_getattr(path, stat);
+}
+
 const struct inode_operations f2fs_encrypted_symlink_inode_operations = {
 	.get_link	= f2fs_encrypted_get_link,
-	.getattr	= f2fs_getattr,
+	.getattr	= f2fs_encrypted_symlink_getattr,
 	.setattr	= f2fs_setattr,
 	.listxattr	= f2fs_listxattr,
 };
-- 
2.32.0