Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   1) // SPDX-License-Identifier: GPL-2.0
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   3)  * Data verification functions, i.e. hooks for ->readpages()
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   4)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   5)  * Copyright 2019 Google LLC
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   6)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   7) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   8) #include "fsverity_private.h"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   9) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  10) #include <crypto/hash.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  11) #include <linux/bio.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  12) #include <linux/ratelimit.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  13) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  14) static struct workqueue_struct *fsverity_read_workqueue;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  15) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  16) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  17)  * hash_at_level() - compute the location of the block's hash at the given level
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  18)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  19)  * @params:	(in) the Merkle tree parameters
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  20)  * @dindex:	(in) the index of the data block being verified
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  21)  * @level:	(in) the level of hash we want (0 is leaf level)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  22)  * @hindex:	(out) the index of the hash block containing the wanted hash
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  23)  * @hoffset:	(out) the byte offset to the wanted hash within the hash block
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  24)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  25) static void hash_at_level(const struct merkle_tree_params *params,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  26) 			  pgoff_t dindex, unsigned int level, pgoff_t *hindex,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  27) 			  unsigned int *hoffset)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  28) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  29) 	pgoff_t position;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  30) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  31) 	/* Offset of the hash within the level's region, in hashes */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  32) 	position = dindex >> (level * params->log_arity);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  33) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  34) 	/* Index of the hash block in the tree overall */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  35) 	*hindex = params->level_start[level] + (position >> params->log_arity);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  36) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  37) 	/* Offset of the wanted hash (in bytes) within the hash block */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  38) 	*hoffset = (position & ((1 << params->log_arity) - 1)) <<
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  39) 		   (params->log_blocksize - params->log_arity);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  40) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  41) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  42) /* Extract a hash from a hash page */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  43) static void extract_hash(struct page *hpage, unsigned int hoffset,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  44) 			 unsigned int hsize, u8 *out)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  45) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  46) 	void *virt = kmap_atomic(hpage);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  47) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  48) 	memcpy(out, virt + hoffset, hsize);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  49) 	kunmap_atomic(virt);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  50) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  51) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  52) static inline int cmp_hashes(const struct fsverity_info *vi,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  53) 			     const u8 *want_hash, const u8 *real_hash,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  54) 			     pgoff_t index, int level)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  55) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  56) 	const unsigned int hsize = vi->tree_params.digest_size;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  57) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  58) 	if (memcmp(want_hash, real_hash, hsize) == 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  59) 		return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  60) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  61) 	fsverity_err(vi->inode,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  62) 		     "FILE CORRUPTED! index=%lu, level=%d, want_hash=%s:%*phN, real_hash=%s:%*phN",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  63) 		     index, level,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  64) 		     vi->tree_params.hash_alg->name, hsize, want_hash,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  65) 		     vi->tree_params.hash_alg->name, hsize, real_hash);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  66) 	return -EBADMSG;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  67) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  68) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  69) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  70)  * Verify a single data page against the file's Merkle tree.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  71)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  72)  * In principle, we need to verify the entire path to the root node.  However,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  73)  * for efficiency the filesystem may cache the hash pages.  Therefore we need
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  74)  * only ascend the tree until an already-verified page is seen, as indicated by
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  75)  * the PageChecked bit being set; then verify the path to that page.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  76)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  77)  * This code currently only supports the case where the verity block size is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  78)  * equal to PAGE_SIZE.  Doing otherwise would be possible but tricky, since we
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  79)  * wouldn't be able to use the PageChecked bit.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  80)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  81)  * Note that multiple processes may race to verify a hash page and mark it
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  82)  * Checked, but it doesn't matter; the result will be the same either way.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  83)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  84)  * Return: true if the page is valid, else false.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  85)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  86) static bool verify_page(struct inode *inode, const struct fsverity_info *vi,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  87) 			struct ahash_request *req, struct page *data_page,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  88) 			unsigned long level0_ra_pages)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  89) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  90) 	const struct merkle_tree_params *params = &vi->tree_params;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  91) 	const unsigned int hsize = params->digest_size;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  92) 	const pgoff_t index = data_page->index;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  93) 	int level;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  94) 	u8 _want_hash[FS_VERITY_MAX_DIGEST_SIZE];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  95) 	const u8 *want_hash;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  96) 	u8 real_hash[FS_VERITY_MAX_DIGEST_SIZE];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  97) 	struct page *hpages[FS_VERITY_MAX_LEVELS];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  98) 	unsigned int hoffsets[FS_VERITY_MAX_LEVELS];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  99) 	int err;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) 	if (WARN_ON_ONCE(!PageLocked(data_page) || PageUptodate(data_page)))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) 		return false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) 	pr_debug_ratelimited("Verifying data page %lu...\n", index);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) 	 * Starting at the leaf level, ascend the tree saving hash pages along
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) 	 * the way until we find a verified hash page, indicated by PageChecked;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) 	 * or until we reach the root.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) 	for (level = 0; level < params->num_levels; level++) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) 		pgoff_t hindex;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) 		unsigned int hoffset;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) 		struct page *hpage;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) 		hash_at_level(params, index, level, &hindex, &hoffset);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) 		pr_debug_ratelimited("Level %d: hindex=%lu, hoffset=%u\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) 				     level, hindex, hoffset);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) 		hpage = inode->i_sb->s_vop->read_merkle_tree_page(inode, hindex,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) 				level == 0 ? level0_ra_pages : 0);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) 		if (IS_ERR(hpage)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) 			err = PTR_ERR(hpage);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) 			fsverity_err(inode,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) 				     "Error %d reading Merkle tree page %lu",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) 				     err, hindex);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) 			goto out;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) 		if (PageChecked(hpage)) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) 			extract_hash(hpage, hoffset, hsize, _want_hash);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) 			want_hash = _want_hash;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) 			put_page(hpage);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) 			pr_debug_ratelimited("Hash page already checked, want %s:%*phN\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) 					     params->hash_alg->name,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) 					     hsize, want_hash);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138) 			goto descend;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) 		}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) 		pr_debug_ratelimited("Hash page not yet checked\n");
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) 		hpages[level] = hpage;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) 		hoffsets[level] = hoffset;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) 	want_hash = vi->root_hash;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) 	pr_debug("Want root hash: %s:%*phN\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) 		 params->hash_alg->name, hsize, want_hash);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) descend:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) 	/* Descend the tree verifying hash pages */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) 	for (; level > 0; level--) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) 		struct page *hpage = hpages[level - 1];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) 		unsigned int hoffset = hoffsets[level - 1];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) 		err = fsverity_hash_page(params, inode, req, hpage, real_hash);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) 		if (err)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) 			goto out;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) 		err = cmp_hashes(vi, want_hash, real_hash, index, level - 1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158) 		if (err)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) 			goto out;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) 		SetPageChecked(hpage);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) 		extract_hash(hpage, hoffset, hsize, _want_hash);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) 		want_hash = _want_hash;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) 		put_page(hpage);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164) 		pr_debug("Verified hash page at level %d, now want %s:%*phN\n",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) 			 level - 1, params->hash_alg->name, hsize, want_hash);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) 	/* Finally, verify the data page */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) 	err = fsverity_hash_page(params, inode, req, data_page, real_hash);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) 	if (err)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171) 		goto out;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172) 	err = cmp_hashes(vi, want_hash, real_hash, index, -1);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173) out:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174) 	for (; level > 0; level--)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175) 		put_page(hpages[level - 1]);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177) 	return err == 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181)  * fsverity_verify_page() - verify a data page
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182)  * @page: the page to verity
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184)  * Verify a page that has just been read from a verity file.  The page must be a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185)  * pagecache page that is still locked and not yet uptodate.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187)  * Return: true if the page is valid, else false.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) bool fsverity_verify_page(struct page *page)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191) 	struct inode *inode = page->mapping->host;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192) 	const struct fsverity_info *vi = inode->i_verity_info;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193) 	struct ahash_request *req;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 194) 	bool valid;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 195) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 196) 	/* This allocation never fails, since it's mempool-backed. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 197) 	req = fsverity_alloc_hash_request(vi->tree_params.hash_alg, GFP_NOFS);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 198) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 199) 	valid = verify_page(inode, vi, req, page, 0);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 200) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 201) 	fsverity_free_hash_request(vi->tree_params.hash_alg, req);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 202) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 203) 	return valid;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 204) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 205) EXPORT_SYMBOL_GPL(fsverity_verify_page);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 206) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 207) #ifdef CONFIG_BLOCK
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 208) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 209)  * fsverity_verify_bio() - verify a 'read' bio that has just completed
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 210)  * @bio: the bio to verify
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 211)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 212)  * Verify a set of pages that have just been read from a verity file.  The pages
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 213)  * must be pagecache pages that are still locked and not yet uptodate.  Pages
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 214)  * that fail verification are set to the Error state.  Verification is skipped
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 215)  * for pages already in the Error state, e.g. due to fscrypt decryption failure.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 216)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 217)  * This is a helper function for use by the ->readpages() method of filesystems
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 218)  * that issue bios to read data directly into the page cache.  Filesystems that
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 219)  * populate the page cache without issuing bios (e.g. non block-based
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 220)  * filesystems) must instead call fsverity_verify_page() directly on each page.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 221)  * All filesystems must also call fsverity_verify_page() on holes.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 222)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 223) void fsverity_verify_bio(struct bio *bio)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 224) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 225) 	struct inode *inode = bio_first_page_all(bio)->mapping->host;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 226) 	const struct fsverity_info *vi = inode->i_verity_info;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 227) 	const struct merkle_tree_params *params = &vi->tree_params;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 228) 	struct ahash_request *req;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 229) 	struct bio_vec *bv;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 230) 	struct bvec_iter_all iter_all;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 231) 	unsigned long max_ra_pages = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 232) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 233) 	/* This allocation never fails, since it's mempool-backed. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 234) 	req = fsverity_alloc_hash_request(params->hash_alg, GFP_NOFS);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 235) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 236) 	if (bio->bi_opf & REQ_RAHEAD) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 237) 		/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 238) 		 * If this bio is for data readahead, then we also do readahead
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 239) 		 * of the first (largest) level of the Merkle tree.  Namely,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 240) 		 * when a Merkle tree page is read, we also try to piggy-back on
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 241) 		 * some additional pages -- up to 1/4 the number of data pages.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 242) 		 *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 243) 		 * This improves sequential read performance, as it greatly
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 244) 		 * reduces the number of I/O requests made to the Merkle tree.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 245) 		 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 246) 		bio_for_each_segment_all(bv, bio, iter_all)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 247) 			max_ra_pages++;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 248) 		max_ra_pages /= 4;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 249) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 250) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 251) 	bio_for_each_segment_all(bv, bio, iter_all) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 252) 		struct page *page = bv->bv_page;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 253) 		unsigned long level0_index = page->index >> params->log_arity;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 254) 		unsigned long level0_ra_pages =
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 255) 			min(max_ra_pages, params->level0_blocks - level0_index);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 256) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 257) 		if (!PageError(page) &&
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 258) 		    !verify_page(inode, vi, req, page, level0_ra_pages))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 259) 			SetPageError(page);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 260) 	}
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 261) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 262) 	fsverity_free_hash_request(params->hash_alg, req);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 263) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 264) EXPORT_SYMBOL_GPL(fsverity_verify_bio);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 265) #endif /* CONFIG_BLOCK */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 266) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 267) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 268)  * fsverity_enqueue_verify_work() - enqueue work on the fs-verity workqueue
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 269)  * @work: the work to enqueue
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 270)  *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 271)  * Enqueue verification work for asynchronous processing.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 272)  */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 273) void fsverity_enqueue_verify_work(struct work_struct *work)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 274) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 275) 	queue_work(fsverity_read_workqueue, work);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 276) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 277) EXPORT_SYMBOL_GPL(fsverity_enqueue_verify_work);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 278) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 279) int __init fsverity_init_workqueue(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 280) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 281) 	/*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 282) 	 * Use an unbound workqueue to allow bios to be verified in parallel
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 283) 	 * even when they happen to complete on the same CPU.  This sacrifices
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 284) 	 * locality, but it's worthwhile since hashing is CPU-intensive.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 285) 	 *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 286) 	 * Also use a high-priority workqueue to prioritize verification work,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 287) 	 * which blocks reads from completing, over regular application tasks.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 288) 	 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 289) 	fsverity_read_workqueue = alloc_workqueue("fsverity_read_queue",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 290) 						  WQ_UNBOUND | WQ_HIGHPRI,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 291) 						  num_online_cpus());
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 292) 	if (!fsverity_read_workqueue)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 293) 		return -ENOMEM;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 294) 	return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 295) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 296) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 297) void __init fsverity_exit_workqueue(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 298) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 299) 	destroy_workqueue(fsverity_read_workqueue);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 300) 	fsverity_read_workqueue = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 301) }