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From: JeffleXu <jefflexu@linux.alibaba.com>
To: David Howells <dhowells@redhat.com>, linux-cachefs@redhat.com
Cc: Trond Myklebust <trondmy@hammerspace.com>,
	Anna Schumaker <anna.schumaker@netapp.com>,
	Steve French <sfrench@samba.org>,
	Dominique Martinet <asmadeus@codewreck.org>,
	Jeff Layton <jlayton@kernel.org>,
	Matthew Wilcox <willy@infradead.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Omar Sandoval <osandov@osandov.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org,
	linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org,
	v9fs-developer@lists.sourceforge.net,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 44/64] cachefiles: Implement key to filename encoding
Date: Wed, 1 Dec 2021 13:46:02 +0800	[thread overview]
Message-ID: <bcefb8f2-576a-b3fc-cc29-89808ebfd7c1@linux.alibaba.com> (raw)
In-Reply-To: <163819640393.215744.15212364106412961104.stgit@warthog.procyon.org.uk>



On 11/29/21 10:33 PM, David Howells wrote:

> +/*
> + * turn the raw key into something cooked
> + * - the key may be up to NAME_MAX in length (including the length word)
> + *   - "base64" encode the strange keys, mapping 3 bytes of raw to four of
> + *     cooked
> + *   - need to cut the cooked key into 252 char lengths (189 raw bytes)
> + */
> +bool cachefiles_cook_key(struct cachefiles_object *object)
> +{
> +	const u8 *key = fscache_get_key(object->cookie), *kend;
> +	unsigned char ch;
> +	unsigned int acc, i, n, nle, nbe, keylen = object->cookie->key_len;
> +	unsigned int b64len, len, print, pad;
> +	char *name, sep;
> +
> +	_enter(",%u,%*phN", keylen, keylen, key);
> +
> +	BUG_ON(keylen > NAME_MAX - 3);
> +
> +	print = 1;
> +	for (i = 0; i < keylen; i++) {
> +		ch = key[i];
> +		print &= cachefiles_filecharmap[ch];
> +	}
> +
> +	/* If the path is usable ASCII, then we render it directly */
> +	if (print) {
> +		len = 1 + keylen + 1;
> +		name = kmalloc(len, GFP_KERNEL);
> +		if (!name)
> +			return false;
> +
> +		name[0] = 'D'; /* Data object type, string encoding */
> +		name[1 + keylen] = 0;
> +		memcpy(name + 1, key, keylen);
> +		goto success;
			^
If we goto success from here,

> +	}
> +
> +	/* See if it makes sense to encode it as "hex,hex,hex" for each 32-bit
> +	 * chunk.  We rely on the key having been padded out to a whole number
> +	 * of 32-bit words.
> +	 */
> +	n = round_up(keylen, 4);
> +	nbe = nle = 0;
> +	for (i = 0; i < n; i += 4) {
> +		u32 be = be32_to_cpu(*(__be32 *)(key + i));
> +		u32 le = le32_to_cpu(*(__le32 *)(key + i));
> +
> +		nbe += 1 + how_many_hex_digits(be);
> +		nle += 1 + how_many_hex_digits(le);
> +	}
> +
> +	b64len = DIV_ROUND_UP(keylen, 3);
> +	pad = b64len * 3 - keylen;
> +	b64len = 2 + b64len * 4; /* Length if we base64-encode it */
> +	_debug("len=%u nbe=%u nle=%u b64=%u", keylen, nbe, nle, b64len);
> +	if (nbe < b64len || nle < b64len) {
> +		unsigned int nlen = min(nbe, nle) + 1;
> +		name = kmalloc(nlen, GFP_KERNEL);
> +		if (!name)
> +			return false;
> +		sep = (nbe <= nle) ? 'S' : 'T'; /* Encoding indicator */
> +		len = 0;
> +		for (i = 0; i < n; i += 4) {
> +			u32 x;
> +			if (nbe <= nle)
> +				x = be32_to_cpu(*(__be32 *)(key + i));
> +			else
> +				x = le32_to_cpu(*(__le32 *)(key + i));
> +			name[len++] = sep;
> +			if (x != 0)
> +				len += snprintf(name + len, nlen - len, "%x", x);
> +			sep = ',';
> +		}
> +		goto success;
> +	}
> +
> +	/* We need to base64-encode it */
> +	name = kmalloc(b64len + 1, GFP_KERNEL);
> +	if (!name)
> +		return false;
> +
> +	name[0] = 'E';
> +	name[1] = '0' + pad;
> +	len = 2;
> +	kend = key + keylen;
> +	do {
> +		acc  = *key++;
> +		if (key < kend) {
> +			acc |= *key++ << 8;
> +			if (key < kend)
> +				acc |= *key++ << 16;
> +		}
> +
> +		name[len++] = cachefiles_charmap[acc & 63];
> +		acc >>= 6;
> +		name[len++] = cachefiles_charmap[acc & 63];
> +		acc >>= 6;
> +		name[len++] = cachefiles_charmap[acc & 63];
> +		acc >>= 6;
> +		name[len++] = cachefiles_charmap[acc & 63];
> +	} while (key < kend);
> +
> +success:
> +	name[len] = 0;
	     ^
then it seems that this will cause an out-of-boundary access.


> +	object->d_name = name;
> +	object->d_name_len = len;
> +	_leave(" = %s", object->d_name);
> +	return true;
> +}
> 

-- 
Thanks,
Jeffle

  reply	other threads:[~2021-12-01  5:46 UTC|newest]

Thread overview: 73+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-29 14:22 [PATCH 00/64] fscache, cachefiles: Rewrite David Howells
2021-11-29 14:22 ` [PATCH 01/64] fscache, cachefiles: Disable configuration David Howells
2021-11-29 14:22 ` [PATCH 02/64] cachefiles: Delete the cachefiles driver pending rewrite David Howells
2021-11-29 14:23 ` [PATCH 03/64] fscache: Remove the contents of the fscache driver, " David Howells
2021-11-29 14:23 ` [PATCH 04/64] netfs: Display the netfs inode number in the netfs_read tracepoint David Howells
2021-11-29 14:23 ` [PATCH 05/64] netfs: Pass a flag to ->prepare_write() to say if there's no alloc'd space David Howells
2021-11-29 14:24 ` [PATCH 06/64] fscache: Introduce new driver David Howells
2021-11-29 14:24 ` [PATCH 07/64] fscache: Implement a hash function David Howells
2021-11-29 14:24 ` [PATCH 08/64] fscache: Implement cache registration David Howells
2021-11-29 14:24 ` [PATCH 09/64] fscache: Implement volume registration David Howells
2021-11-29 14:25 ` [PATCH 10/64] fscache: Implement cookie registration David Howells
2021-11-29 14:25 ` [PATCH 11/64] fscache: Implement cache-level access helpers David Howells
2021-11-29 14:25 ` [PATCH 12/64] fscache: Implement volume-level " David Howells
2021-11-29 14:25 ` [PATCH 13/64] fscache: Implement cookie-level " David Howells
2021-11-29 14:26 ` [PATCH 14/64] fscache: Implement functions add/remove a cache David Howells
2021-11-29 14:26 ` [PATCH 15/64] fscache: Provide and use cache methods to lookup/create/free a volume David Howells
2021-11-29 14:26 ` [PATCH 16/64] fscache: Add a function for a cache backend to note an I/O error David Howells
2021-11-29 14:26 ` [PATCH 17/64] fscache: Implement simple cookie state machine David Howells
2021-11-29 14:26 ` [PATCH 18/64] fscache: Implement cookie user counting and resource pinning David Howells
2021-11-29 14:27 ` [PATCH 19/64] fscache: Implement cookie invalidation David Howells
2021-11-29 14:27 ` [PATCH 20/64] fscache: Provide a means to begin an operation David Howells
2021-11-29 14:28 ` [PATCH 21/64] fscache: Count data storage objects in a cache David Howells
2021-11-29 14:28 ` [PATCH 22/64] fscache: Provide read/write stat counters for the cache David Howells
2021-11-29 14:28 ` [PATCH 23/64] fscache: Provide a function to let the netfs update its coherency data David Howells
2021-11-29 14:28 ` [PATCH 24/64] netfs: Pass more information on how to deal with a hole in the cache David Howells
2021-12-06 11:42   ` JeffleXu
2021-12-09 16:49   ` David Howells
2021-11-29 14:28 ` [PATCH 25/64] fscache: Implement raw I/O interface David Howells
2021-11-29 14:29 ` [PATCH 26/64] fscache: Implement higher-level write " David Howells
2021-11-29 14:29 ` [PATCH 27/64] vfs, fscache: Implement pinning of cache usage for writeback David Howells
2021-11-29 14:29 ` [PATCH 28/64] fscache: Provide a function to note the release of a page David Howells
2021-11-29 14:30 ` [PATCH 29/64] fscache: Provide a function to resize a cookie David Howells
2021-11-29 14:30 ` [PATCH 30/64] cachefiles: Introduce rewritten driver David Howells
2021-11-29 14:30 ` [PATCH 31/64] cachefiles: Define structs David Howells
2021-11-29 14:30 ` [PATCH 32/64] cachefiles: Add some error injection support David Howells
2021-11-29 14:30 ` [PATCH 33/64] cachefiles: Add a couple of tracepoints for logging errors David Howells
2021-11-29 14:31 ` [PATCH 34/64] cachefiles: Add cache error reporting macro David Howells
2021-11-29 14:31 ` [PATCH 35/64] cachefiles: Add security derivation David Howells
2021-11-29 14:31 ` [PATCH 36/64] cachefiles: Register a miscdev and parse commands over it David Howells
2021-11-29 14:31 ` [PATCH 37/64] cachefiles: Provide a function to check how much space there is David Howells
2021-11-29 14:31 ` [PATCH 38/64] vfs, cachefiles: Mark a backing file in use with an inode flag David Howells
2021-11-29 14:31 ` [PATCH 39/64] cachefiles: Implement a function to get/create a directory in the cache David Howells
2021-11-29 14:32 ` [PATCH 40/64] cachefiles: Implement cache registration and withdrawal David Howells
2021-11-29 14:32 ` [PATCH 41/64] cachefiles: Implement volume support David Howells
2021-11-29 14:33 ` [PATCH 42/64] cachefiles: Add tracepoints for calls to the VFS David Howells
2021-11-29 14:33 ` [PATCH 43/64] cachefiles: Implement object lifecycle funcs David Howells
2021-11-29 14:33 ` [PATCH 44/64] cachefiles: Implement key to filename encoding David Howells
2021-12-01  5:46   ` JeffleXu [this message]
2021-12-01  8:29   ` David Howells
2021-11-29 14:33 ` [PATCH 45/64] cachefiles: Implement metadata/coherency data storage in xattrs David Howells
2021-11-29 14:33 ` [PATCH 46/64] cachefiles: Mark a backing file in use with an inode flag David Howells
2021-11-29 14:33 ` [PATCH 47/64] cachefiles: Implement culling daemon commands David Howells
2021-11-29 14:34 ` [PATCH 48/64] cachefiles: Implement backing file wrangling David Howells
2021-11-29 14:34 ` [PATCH 49/64] cachefiles: Implement begin and end I/O operation David Howells
2021-11-29 14:34 ` [PATCH 50/64] cachefiles: Implement cookie resize for truncate David Howells
2021-11-29 14:34 ` [PATCH 51/64] cachefiles: Implement the I/O routines David Howells
2021-11-30 16:15   ` Nathan Chancellor
2021-11-30 21:05   ` David Howells
2021-11-29 14:34 ` [PATCH 52/64] cachefiles: Allow cachefiles to actually function David Howells
2021-11-29 14:35 ` [PATCH 53/64] fscache, cachefiles: Display stats of no-space events David Howells
2021-11-29 14:35 ` [PATCH 54/64] fscache, cachefiles: Display stat of culling events David Howells
2021-11-29 14:36 ` [PATCH 55/64] afs: Handle len being extending over page end in write_begin/write_end David Howells
2021-11-29 14:36 ` [PATCH 56/64] afs: Fix afs_write_end() to handle len > page size David Howells
2021-11-29 14:36 ` [PATCH 57/64] afs: Convert afs to use the new fscache API David Howells
2021-11-29 14:37 ` [PATCH 58/64] afs: Copy local writes to the cache when writing to the server David Howells
2021-11-29 14:37 ` [PATCH 59/64] afs: Skip truncation on the server of data we haven't written yet David Howells
2021-11-29 14:37 ` [PATCH 60/64] 9p: Use fscache indexing rewrite and reenable caching David Howells
2021-11-29 14:37 ` [PATCH 61/64] 9p: Copy local writes to the cache when writing to the server David Howells
2021-11-29 14:38 ` [PATCH 62/64] nfs: Convert to new fscache volume/cookie API David Howells
2021-11-29 14:38 ` [PATCH 63/64] cifs: Support fscache indexing rewrite (untested) David Howells
2021-11-29 14:38 ` [PATCH 64/64] fscache: Rewrite documentation David Howells
2021-11-29 18:12 ` [PATCH 00/64] fscache, cachefiles: Rewrite Linus Torvalds
2021-11-29 21:40 ` [PATCH 35/64] cachefiles: Add security derivation David Howells

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