diff options
Diffstat (limited to 'security/integrity/ima/ima_crypto.c')
| -rw-r--r-- | security/integrity/ima/ima_crypto.c | 698 |
1 files changed, 698 insertions, 0 deletions
diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c new file mode 100644 index 000000000..f0b244989 --- /dev/null +++ b/security/integrity/ima/ima_crypto.c @@ -0,0 +1,698 @@ +/* + * Copyright (C) 2005,2006,2007,2008 IBM Corporation + * + * Authors: + * Mimi Zohar <zohar@us.ibm.com> + * Kylene Hall <kjhall@us.ibm.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, version 2 of the License. + * + * File: ima_crypto.c + * Calculates md5/sha1 file hash, template hash, boot-aggreate hash + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/kernel.h> +#include <linux/moduleparam.h> +#include <linux/ratelimit.h> +#include <linux/file.h> +#include <linux/crypto.h> +#include <linux/scatterlist.h> +#include <linux/err.h> +#include <linux/slab.h> +#include <crypto/hash.h> + +#include "ima.h" + +/* minimum file size for ahash use */ +static unsigned long ima_ahash_minsize; +module_param_named(ahash_minsize, ima_ahash_minsize, ulong, 0644); +MODULE_PARM_DESC(ahash_minsize, "Minimum file size for ahash use"); + +/* default is 0 - 1 page. */ +static int ima_maxorder; +static unsigned int ima_bufsize = PAGE_SIZE; + +static int param_set_bufsize(const char *val, const struct kernel_param *kp) +{ + unsigned long long size; + int order; + + size = memparse(val, NULL); + order = get_order(size); + if (order >= MAX_ORDER) + return -EINVAL; + ima_maxorder = order; + ima_bufsize = PAGE_SIZE << order; + return 0; +} + +static const struct kernel_param_ops param_ops_bufsize = { + .set = param_set_bufsize, + .get = param_get_uint, +}; +#define param_check_bufsize(name, p) __param_check(name, p, unsigned int) + +module_param_named(ahash_bufsize, ima_bufsize, bufsize, 0644); +MODULE_PARM_DESC(ahash_bufsize, "Maximum ahash buffer size"); + +static struct crypto_shash *ima_shash_tfm; +static struct crypto_ahash *ima_ahash_tfm; + +int __init ima_init_crypto(void) +{ + long rc; + + ima_shash_tfm = crypto_alloc_shash(hash_algo_name[ima_hash_algo], 0, 0); + if (IS_ERR(ima_shash_tfm)) { + rc = PTR_ERR(ima_shash_tfm); + pr_err("Can not allocate %s (reason: %ld)\n", + hash_algo_name[ima_hash_algo], rc); + return rc; + } + pr_info("Allocated hash algorithm: %s\n", + hash_algo_name[ima_hash_algo]); + return 0; +} + +static struct crypto_shash *ima_alloc_tfm(enum hash_algo algo) +{ + struct crypto_shash *tfm = ima_shash_tfm; + int rc; + + if (algo < 0 || algo >= HASH_ALGO__LAST) + algo = ima_hash_algo; + + if (algo != ima_hash_algo) { + tfm = crypto_alloc_shash(hash_algo_name[algo], 0, 0); + if (IS_ERR(tfm)) { + rc = PTR_ERR(tfm); + pr_err("Can not allocate %s (reason: %d)\n", + hash_algo_name[algo], rc); + } + } + return tfm; +} + +static void ima_free_tfm(struct crypto_shash *tfm) +{ + if (tfm != ima_shash_tfm) + crypto_free_shash(tfm); +} + +/** + * ima_alloc_pages() - Allocate contiguous pages. + * @max_size: Maximum amount of memory to allocate. + * @allocated_size: Returned size of actual allocation. + * @last_warn: Should the min_size allocation warn or not. + * + * Tries to do opportunistic allocation for memory first trying to allocate + * max_size amount of memory and then splitting that until zero order is + * reached. Allocation is tried without generating allocation warnings unless + * last_warn is set. Last_warn set affects only last allocation of zero order. + * + * By default, ima_maxorder is 0 and it is equivalent to kmalloc(GFP_KERNEL) + * + * Return pointer to allocated memory, or NULL on failure. + */ +static void *ima_alloc_pages(loff_t max_size, size_t *allocated_size, + int last_warn) +{ + void *ptr; + int order = ima_maxorder; + gfp_t gfp_mask = __GFP_RECLAIM | __GFP_NOWARN | __GFP_NORETRY; + + if (order) + order = min(get_order(max_size), order); + + for (; order; order--) { + ptr = (void *)__get_free_pages(gfp_mask, order); + if (ptr) { + *allocated_size = PAGE_SIZE << order; + return ptr; + } + } + + /* order is zero - one page */ + + gfp_mask = GFP_KERNEL; + + if (!last_warn) + gfp_mask |= __GFP_NOWARN; + + ptr = (void *)__get_free_pages(gfp_mask, 0); + if (ptr) { + *allocated_size = PAGE_SIZE; + return ptr; + } + + *allocated_size = 0; + return NULL; +} + +/** + * ima_free_pages() - Free pages allocated by ima_alloc_pages(). + * @ptr: Pointer to allocated pages. + * @size: Size of allocated buffer. + */ +static void ima_free_pages(void *ptr, size_t size) +{ + if (!ptr) + return; + free_pages((unsigned long)ptr, get_order(size)); +} + +static struct crypto_ahash *ima_alloc_atfm(enum hash_algo algo) +{ + struct crypto_ahash *tfm = ima_ahash_tfm; + int rc; + + if (algo < 0 || algo >= HASH_ALGO__LAST) + algo = ima_hash_algo; + + if (algo != ima_hash_algo || !tfm) { + tfm = crypto_alloc_ahash(hash_algo_name[algo], 0, 0); + if (!IS_ERR(tfm)) { + if (algo == ima_hash_algo) + ima_ahash_tfm = tfm; + } else { + rc = PTR_ERR(tfm); + pr_err("Can not allocate %s (reason: %d)\n", + hash_algo_name[algo], rc); + } + } + return tfm; +} + +static void ima_free_atfm(struct crypto_ahash *tfm) +{ + if (tfm != ima_ahash_tfm) + crypto_free_ahash(tfm); +} + +static inline int ahash_wait(int err, struct crypto_wait *wait) +{ + + err = crypto_wait_req(err, wait); + + if (err) + pr_crit_ratelimited("ahash calculation failed: err: %d\n", err); + + return err; +} + +static int ima_calc_file_hash_atfm(struct file *file, + struct ima_digest_data *hash, + struct crypto_ahash *tfm) +{ + loff_t i_size, offset; + char *rbuf[2] = { NULL, }; + int rc, rbuf_len, active = 0, ahash_rc = 0; + struct ahash_request *req; + struct scatterlist sg[1]; + struct crypto_wait wait; + size_t rbuf_size[2]; + + hash->length = crypto_ahash_digestsize(tfm); + + req = ahash_request_alloc(tfm, GFP_KERNEL); + if (!req) + return -ENOMEM; + + crypto_init_wait(&wait); + ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG | + CRYPTO_TFM_REQ_MAY_SLEEP, + crypto_req_done, &wait); + + rc = ahash_wait(crypto_ahash_init(req), &wait); + if (rc) + goto out1; + + i_size = i_size_read(file_inode(file)); + + if (i_size == 0) + goto out2; + + /* + * Try to allocate maximum size of memory. + * Fail if even a single page cannot be allocated. + */ + rbuf[0] = ima_alloc_pages(i_size, &rbuf_size[0], 1); + if (!rbuf[0]) { + rc = -ENOMEM; + goto out1; + } + + /* Only allocate one buffer if that is enough. */ + if (i_size > rbuf_size[0]) { + /* + * Try to allocate secondary buffer. If that fails fallback to + * using single buffering. Use previous memory allocation size + * as baseline for possible allocation size. + */ + rbuf[1] = ima_alloc_pages(i_size - rbuf_size[0], + &rbuf_size[1], 0); + } + + for (offset = 0; offset < i_size; offset += rbuf_len) { + if (!rbuf[1] && offset) { + /* Not using two buffers, and it is not the first + * read/request, wait for the completion of the + * previous ahash_update() request. + */ + rc = ahash_wait(ahash_rc, &wait); + if (rc) + goto out3; + } + /* read buffer */ + rbuf_len = min_t(loff_t, i_size - offset, rbuf_size[active]); + rc = integrity_kernel_read(file, offset, rbuf[active], + rbuf_len); + if (rc != rbuf_len) { + if (rc >= 0) + rc = -EINVAL; + /* + * Forward current rc, do not overwrite with return value + * from ahash_wait() + */ + ahash_wait(ahash_rc, &wait); + goto out3; + } + + if (rbuf[1] && offset) { + /* Using two buffers, and it is not the first + * read/request, wait for the completion of the + * previous ahash_update() request. + */ + rc = ahash_wait(ahash_rc, &wait); + if (rc) + goto out3; + } + + sg_init_one(&sg[0], rbuf[active], rbuf_len); + ahash_request_set_crypt(req, sg, NULL, rbuf_len); + + ahash_rc = crypto_ahash_update(req); + + if (rbuf[1]) + active = !active; /* swap buffers, if we use two */ + } + /* wait for the last update request to complete */ + rc = ahash_wait(ahash_rc, &wait); +out3: + ima_free_pages(rbuf[0], rbuf_size[0]); + ima_free_pages(rbuf[1], rbuf_size[1]); +out2: + if (!rc) { + ahash_request_set_crypt(req, NULL, hash->digest, 0); + rc = ahash_wait(crypto_ahash_final(req), &wait); + } +out1: + ahash_request_free(req); + return rc; +} + +static int ima_calc_file_ahash(struct file *file, struct ima_digest_data *hash) +{ + struct crypto_ahash *tfm; + int rc; + + tfm = ima_alloc_atfm(hash->algo); + if (IS_ERR(tfm)) + return PTR_ERR(tfm); + + rc = ima_calc_file_hash_atfm(file, hash, tfm); + + ima_free_atfm(tfm); + + return rc; +} + +static int ima_calc_file_hash_tfm(struct file *file, + struct ima_digest_data *hash, + struct crypto_shash *tfm) +{ + loff_t i_size, offset = 0; + char *rbuf; + int rc; + SHASH_DESC_ON_STACK(shash, tfm); + + shash->tfm = tfm; + shash->flags = 0; + + hash->length = crypto_shash_digestsize(tfm); + + rc = crypto_shash_init(shash); + if (rc != 0) + return rc; + + i_size = i_size_read(file_inode(file)); + + if (i_size == 0) + goto out; + + rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL); + if (!rbuf) + return -ENOMEM; + + while (offset < i_size) { + int rbuf_len; + + rbuf_len = integrity_kernel_read(file, offset, rbuf, PAGE_SIZE); + if (rbuf_len < 0) { + rc = rbuf_len; + break; + } + if (rbuf_len == 0) + break; + offset += rbuf_len; + + rc = crypto_shash_update(shash, rbuf, rbuf_len); + if (rc) + break; + } + kfree(rbuf); +out: + if (!rc) + rc = crypto_shash_final(shash, hash->digest); + return rc; +} + +static int ima_calc_file_shash(struct file *file, struct ima_digest_data *hash) +{ + struct crypto_shash *tfm; + int rc; + + tfm = ima_alloc_tfm(hash->algo); + if (IS_ERR(tfm)) + return PTR_ERR(tfm); + + rc = ima_calc_file_hash_tfm(file, hash, tfm); + + ima_free_tfm(tfm); + + return rc; +} + +/* + * ima_calc_file_hash - calculate file hash + * + * Asynchronous hash (ahash) allows using HW acceleration for calculating + * a hash. ahash performance varies for different data sizes on different + * crypto accelerators. shash performance might be better for smaller files. + * The 'ima.ahash_minsize' module parameter allows specifying the best + * minimum file size for using ahash on the system. + * + * If the ima.ahash_minsize parameter is not specified, this function uses + * shash for the hash calculation. If ahash fails, it falls back to using + * shash. + */ +int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash) +{ + loff_t i_size; + int rc; + struct file *f = file; + bool new_file_instance = false; + + /* + * For consistency, fail file's opened with the O_DIRECT flag on + * filesystems mounted with/without DAX option. + */ + if (file->f_flags & O_DIRECT) { + hash->length = hash_digest_size[ima_hash_algo]; + hash->algo = ima_hash_algo; + return -EINVAL; + } + + /* Open a new file instance in O_RDONLY if we cannot read */ + if (!(file->f_mode & FMODE_READ)) { + int flags = file->f_flags & ~(O_WRONLY | O_APPEND | + O_TRUNC | O_CREAT | O_NOCTTY | O_EXCL); + flags |= O_RDONLY; + f = dentry_open(&file->f_path, flags, file->f_cred); + if (IS_ERR(f)) + return PTR_ERR(f); + + new_file_instance = true; + } + + i_size = i_size_read(file_inode(f)); + + if (ima_ahash_minsize && i_size >= ima_ahash_minsize) { + rc = ima_calc_file_ahash(f, hash); + if (!rc) + goto out; + } + + rc = ima_calc_file_shash(f, hash); +out: + if (new_file_instance) + fput(f); + return rc; +} + +/* + * Calculate the hash of template data + */ +static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data, + struct ima_template_desc *td, + int num_fields, + struct ima_digest_data *hash, + struct crypto_shash *tfm) +{ + SHASH_DESC_ON_STACK(shash, tfm); + int rc, i; + + shash->tfm = tfm; + shash->flags = 0; + + hash->length = crypto_shash_digestsize(tfm); + + rc = crypto_shash_init(shash); + if (rc != 0) + return rc; + + for (i = 0; i < num_fields; i++) { + u8 buffer[IMA_EVENT_NAME_LEN_MAX + 1] = { 0 }; + u8 *data_to_hash = field_data[i].data; + u32 datalen = field_data[i].len; + u32 datalen_to_hash = + !ima_canonical_fmt ? datalen : cpu_to_le32(datalen); + + if (strcmp(td->name, IMA_TEMPLATE_IMA_NAME) != 0) { + rc = crypto_shash_update(shash, + (const u8 *) &datalen_to_hash, + sizeof(datalen_to_hash)); + if (rc) + break; + } else if (strcmp(td->fields[i]->field_id, "n") == 0) { + memcpy(buffer, data_to_hash, datalen); + data_to_hash = buffer; + datalen = IMA_EVENT_NAME_LEN_MAX + 1; + } + rc = crypto_shash_update(shash, data_to_hash, datalen); + if (rc) + break; + } + + if (!rc) + rc = crypto_shash_final(shash, hash->digest); + + return rc; +} + +int ima_calc_field_array_hash(struct ima_field_data *field_data, + struct ima_template_desc *desc, int num_fields, + struct ima_digest_data *hash) +{ + struct crypto_shash *tfm; + int rc; + + tfm = ima_alloc_tfm(hash->algo); + if (IS_ERR(tfm)) + return PTR_ERR(tfm); + + rc = ima_calc_field_array_hash_tfm(field_data, desc, num_fields, + hash, tfm); + + ima_free_tfm(tfm); + + return rc; +} + +static int calc_buffer_ahash_atfm(const void *buf, loff_t len, + struct ima_digest_data *hash, + struct crypto_ahash *tfm) +{ + struct ahash_request *req; + struct scatterlist sg; + struct crypto_wait wait; + int rc, ahash_rc = 0; + + hash->length = crypto_ahash_digestsize(tfm); + + req = ahash_request_alloc(tfm, GFP_KERNEL); + if (!req) + return -ENOMEM; + + crypto_init_wait(&wait); + ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG | + CRYPTO_TFM_REQ_MAY_SLEEP, + crypto_req_done, &wait); + + rc = ahash_wait(crypto_ahash_init(req), &wait); + if (rc) + goto out; + + sg_init_one(&sg, buf, len); + ahash_request_set_crypt(req, &sg, NULL, len); + + ahash_rc = crypto_ahash_update(req); + + /* wait for the update request to complete */ + rc = ahash_wait(ahash_rc, &wait); + if (!rc) { + ahash_request_set_crypt(req, NULL, hash->digest, 0); + rc = ahash_wait(crypto_ahash_final(req), &wait); + } +out: + ahash_request_free(req); + return rc; +} + +static int calc_buffer_ahash(const void *buf, loff_t len, + struct ima_digest_data *hash) +{ + struct crypto_ahash *tfm; + int rc; + + tfm = ima_alloc_atfm(hash->algo); + if (IS_ERR(tfm)) + return PTR_ERR(tfm); + + rc = calc_buffer_ahash_atfm(buf, len, hash, tfm); + + ima_free_atfm(tfm); + + return rc; +} + +static int calc_buffer_shash_tfm(const void *buf, loff_t size, + struct ima_digest_data *hash, + struct crypto_shash *tfm) +{ + SHASH_DESC_ON_STACK(shash, tfm); + unsigned int len; + int rc; + + shash->tfm = tfm; + shash->flags = 0; + + hash->length = crypto_shash_digestsize(tfm); + + rc = crypto_shash_init(shash); + if (rc != 0) + return rc; + + while (size) { + len = size < PAGE_SIZE ? size : PAGE_SIZE; + rc = crypto_shash_update(shash, buf, len); + if (rc) + break; + buf += len; + size -= len; + } + + if (!rc) + rc = crypto_shash_final(shash, hash->digest); + return rc; +} + +static int calc_buffer_shash(const void *buf, loff_t len, + struct ima_digest_data *hash) +{ + struct crypto_shash *tfm; + int rc; + + tfm = ima_alloc_tfm(hash->algo); + if (IS_ERR(tfm)) + return PTR_ERR(tfm); + + rc = calc_buffer_shash_tfm(buf, len, hash, tfm); + + ima_free_tfm(tfm); + return rc; +} + +int ima_calc_buffer_hash(const void *buf, loff_t len, + struct ima_digest_data *hash) +{ + int rc; + + if (ima_ahash_minsize && len >= ima_ahash_minsize) { + rc = calc_buffer_ahash(buf, len, hash); + if (!rc) + return 0; + } + + return calc_buffer_shash(buf, len, hash); +} + +static void ima_pcrread(int idx, u8 *pcr) +{ + if (!ima_tpm_chip) + return; + + if (tpm_pcr_read(ima_tpm_chip, idx, pcr) != 0) + pr_err("Error Communicating to TPM chip\n"); +} + +/* + * Calculate the boot aggregate hash + */ +static int ima_calc_boot_aggregate_tfm(char *digest, + struct crypto_shash *tfm) +{ + u8 pcr_i[TPM_DIGEST_SIZE]; + int rc, i; + SHASH_DESC_ON_STACK(shash, tfm); + + shash->tfm = tfm; + shash->flags = 0; + + rc = crypto_shash_init(shash); + if (rc != 0) + return rc; + + /* cumulative sha1 over tpm registers 0-7 */ + for (i = TPM_PCR0; i < TPM_PCR8; i++) { + ima_pcrread(i, pcr_i); + /* now accumulate with current aggregate */ + rc = crypto_shash_update(shash, pcr_i, TPM_DIGEST_SIZE); + if (rc != 0) + return rc; + } + if (!rc) + crypto_shash_final(shash, digest); + return rc; +} + +int ima_calc_boot_aggregate(struct ima_digest_data *hash) +{ + struct crypto_shash *tfm; + int rc; + + tfm = ima_alloc_tfm(hash->algo); + if (IS_ERR(tfm)) + return PTR_ERR(tfm); + + hash->length = crypto_shash_digestsize(tfm); + rc = ima_calc_boot_aggregate_tfm(hash->digest, tfm); + + ima_free_tfm(tfm); + + return rc; +} |