diff options
| -rw-r--r-- | security/keys/big_key.c | 110 |
1 files changed, 87 insertions, 23 deletions
diff --git a/security/keys/big_key.c b/security/keys/big_key.c index 929e14978c42..fa728f662a6f 100644 --- a/security/keys/big_key.c +++ b/security/keys/big_key.c @@ -22,6 +22,13 @@ #include <keys/big_key-type.h> #include <crypto/aead.h> +struct big_key_buf { + unsigned int nr_pages; + void *virt; + struct scatterlist *sg; + struct page *pages[]; +}; + /* * Layout of key payload words. */ @@ -91,10 +98,9 @@ static DEFINE_MUTEX(big_key_aead_lock); /* * Encrypt/decrypt big_key data */ -static int big_key_crypt(enum big_key_op op, u8 *data, size_t datalen, u8 *key) +static int big_key_crypt(enum big_key_op op, struct big_key_buf *buf, size_t datalen, u8 *key) { int ret; - struct scatterlist sgio; struct aead_request *aead_req; /* We always use a zero nonce. The reason we can get away with this is * because we're using a different randomly generated key for every @@ -109,8 +115,7 @@ static int big_key_crypt(enum big_key_op op, u8 *data, size_t datalen, u8 *key) return -ENOMEM; memset(zero_nonce, 0, sizeof(zero_nonce)); - sg_init_one(&sgio, data, datalen + (op == BIG_KEY_ENC ? ENC_AUTHTAG_SIZE : 0)); - aead_request_set_crypt(aead_req, &sgio, &sgio, datalen, zero_nonce); + aead_request_set_crypt(aead_req, buf->sg, buf->sg, datalen, zero_nonce); aead_request_set_callback(aead_req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL); aead_request_set_ad(aead_req, 0); @@ -130,21 +135,81 @@ error: } /* + * Free up the buffer. + */ +static void big_key_free_buffer(struct big_key_buf *buf) +{ + unsigned int i; + + if (buf->virt) { + memset(buf->virt, 0, buf->nr_pages * PAGE_SIZE); + vunmap(buf->virt); + } + + for (i = 0; i < buf->nr_pages; i++) + if (buf->pages[i]) + __free_page(buf->pages[i]); + + kfree(buf); +} + +/* + * Allocate a buffer consisting of a set of pages with a virtual mapping + * applied over them. + */ +static void *big_key_alloc_buffer(size_t len) +{ + struct big_key_buf *buf; + unsigned int npg = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; + unsigned int i, l; + + buf = kzalloc(sizeof(struct big_key_buf) + + sizeof(struct page) * npg + + sizeof(struct scatterlist) * npg, + GFP_KERNEL); + if (!buf) + return NULL; + + buf->nr_pages = npg; + buf->sg = (void *)(buf->pages + npg); + sg_init_table(buf->sg, npg); + + for (i = 0; i < buf->nr_pages; i++) { + buf->pages[i] = alloc_page(GFP_KERNEL); + if (!buf->pages[i]) + goto nomem; + + l = min_t(size_t, len, PAGE_SIZE); + sg_set_page(&buf->sg[i], buf->pages[i], l, 0); + len -= l; + } + + buf->virt = vmap(buf->pages, buf->nr_pages, VM_MAP, PAGE_KERNEL); + if (!buf->virt) + goto nomem; + + return buf; + +nomem: + big_key_free_buffer(buf); + return NULL; +} + +/* * Preparse a big key */ int big_key_preparse(struct key_preparsed_payload *prep) { + struct big_key_buf *buf; struct path *path = (struct path *)&prep->payload.data[big_key_path]; struct file *file; u8 *enckey; - u8 *data = NULL; ssize_t written; - size_t datalen = prep->datalen; + size_t datalen = prep->datalen, enclen = datalen + ENC_AUTHTAG_SIZE; int ret; - ret = -EINVAL; if (datalen <= 0 || datalen > 1024 * 1024 || !prep->data) - goto error; + return -EINVAL; /* Set an arbitrary quota */ prep->quotalen = 16; @@ -157,13 +222,12 @@ int big_key_preparse(struct key_preparsed_payload *prep) * * File content is stored encrypted with randomly generated key. */ - size_t enclen = datalen + ENC_AUTHTAG_SIZE; loff_t pos = 0; - data = kmalloc(enclen, GFP_KERNEL); - if (!data) + buf = big_key_alloc_buffer(enclen); + if (!buf) return -ENOMEM; - memcpy(data, prep->data, datalen); + memcpy(buf->virt, prep->data, datalen); /* generate random key */ enckey = kmalloc(ENC_KEY_SIZE, GFP_KERNEL); @@ -176,7 +240,7 @@ int big_key_preparse(struct key_preparsed_payload *prep) goto err_enckey; /* encrypt aligned data */ - ret = big_key_crypt(BIG_KEY_ENC, data, datalen, enckey); + ret = big_key_crypt(BIG_KEY_ENC, buf, datalen, enckey); if (ret) goto err_enckey; @@ -187,7 +251,7 @@ int big_key_preparse(struct key_preparsed_payload *prep) goto err_enckey; } - written = kernel_write(file, data, enclen, &pos); + written = kernel_write(file, buf->virt, enclen, &pos); if (written != enclen) { ret = written; if (written >= 0) @@ -202,7 +266,7 @@ int big_key_preparse(struct key_preparsed_payload *prep) *path = file->f_path; path_get(path); fput(file); - kzfree(data); + big_key_free_buffer(buf); } else { /* Just store the data in a buffer */ void *data = kmalloc(datalen, GFP_KERNEL); @@ -220,7 +284,7 @@ err_fput: err_enckey: kzfree(enckey); error: - kzfree(data); + big_key_free_buffer(buf); return ret; } @@ -298,15 +362,15 @@ long big_key_read(const struct key *key, char __user *buffer, size_t buflen) return datalen; if (datalen > BIG_KEY_FILE_THRESHOLD) { + struct big_key_buf *buf; struct path *path = (struct path *)&key->payload.data[big_key_path]; struct file *file; - u8 *data; u8 *enckey = (u8 *)key->payload.data[big_key_data]; size_t enclen = datalen + ENC_AUTHTAG_SIZE; loff_t pos = 0; - data = kmalloc(enclen, GFP_KERNEL); - if (!data) + buf = big_key_alloc_buffer(enclen); + if (!buf) return -ENOMEM; file = dentry_open(path, O_RDONLY, current_cred()); @@ -316,26 +380,26 @@ long big_key_read(const struct key *key, char __user *buffer, size_t buflen) } /* read file to kernel and decrypt */ - ret = kernel_read(file, data, enclen, &pos); + ret = kernel_read(file, buf->virt, enclen, &pos); if (ret >= 0 && ret != enclen) { ret = -EIO; goto err_fput; } - ret = big_key_crypt(BIG_KEY_DEC, data, enclen, enckey); + ret = big_key_crypt(BIG_KEY_DEC, buf, enclen, enckey); if (ret) goto err_fput; ret = datalen; /* copy decrypted data to user */ - if (copy_to_user(buffer, data, datalen) != 0) + if (copy_to_user(buffer, buf->virt, datalen) != 0) ret = -EFAULT; err_fput: fput(file); error: - kzfree(data); + big_key_free_buffer(buf); } else { ret = datalen; if (copy_to_user(buffer, key->payload.data[big_key_data], |