diff options
Diffstat (limited to 'fs/crypto')
| -rw-r--r-- | fs/crypto/Kconfig | 18 | ||||
| -rw-r--r-- | fs/crypto/Makefile | 3 | ||||
| -rw-r--r-- | fs/crypto/crypto.c | 568 | ||||
| -rw-r--r-- | fs/crypto/fname.c | 424 | ||||
| -rw-r--r-- | fs/crypto/keyinfo.c | 304 | ||||
| -rw-r--r-- | fs/crypto/policy.c | 229 |
6 files changed, 1546 insertions, 0 deletions
diff --git a/fs/crypto/Kconfig b/fs/crypto/Kconfig new file mode 100644 index 000000000..92348faf9 --- /dev/null +++ b/fs/crypto/Kconfig @@ -0,0 +1,18 @@ +config FS_ENCRYPTION + tristate "FS Encryption (Per-file encryption)" + depends on BLOCK + select CRYPTO + select CRYPTO_AES + select CRYPTO_CBC + select CRYPTO_ECB + select CRYPTO_XTS + select CRYPTO_CTS + select CRYPTO_CTR + select CRYPTO_SHA256 + select KEYS + select ENCRYPTED_KEYS + help + Enable encryption of files and directories. This + feature is similar to ecryptfs, but it is more memory + efficient since it avoids caching the encrypted and + decrypted pages in the page cache. diff --git a/fs/crypto/Makefile b/fs/crypto/Makefile new file mode 100644 index 000000000..f17684c48 --- /dev/null +++ b/fs/crypto/Makefile @@ -0,0 +1,3 @@ +obj-$(CONFIG_FS_ENCRYPTION) += fscrypto.o + +fscrypto-y := crypto.o fname.o policy.o keyinfo.o diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c new file mode 100644 index 000000000..2fc8c43ce --- /dev/null +++ b/fs/crypto/crypto.c @@ -0,0 +1,568 @@ +/* + * This contains encryption functions for per-file encryption. + * + * Copyright (C) 2015, Google, Inc. + * Copyright (C) 2015, Motorola Mobility + * + * Written by Michael Halcrow, 2014. + * + * Filename encryption additions + * Uday Savagaonkar, 2014 + * Encryption policy handling additions + * Ildar Muslukhov, 2014 + * Add fscrypt_pullback_bio_page() + * Jaegeuk Kim, 2015. + * + * This has not yet undergone a rigorous security audit. + * + * The usage of AES-XTS should conform to recommendations in NIST + * Special Publication 800-38E and IEEE P1619/D16. + */ + +#include <linux/pagemap.h> +#include <linux/mempool.h> +#include <linux/module.h> +#include <linux/scatterlist.h> +#include <linux/ratelimit.h> +#include <linux/bio.h> +#include <linux/dcache.h> +#include <linux/namei.h> +#include <linux/fscrypto.h> +#include <linux/ecryptfs.h> + +static unsigned int num_prealloc_crypto_pages = 32; +static unsigned int num_prealloc_crypto_ctxs = 128; + +module_param(num_prealloc_crypto_pages, uint, 0444); +MODULE_PARM_DESC(num_prealloc_crypto_pages, + "Number of crypto pages to preallocate"); +module_param(num_prealloc_crypto_ctxs, uint, 0444); +MODULE_PARM_DESC(num_prealloc_crypto_ctxs, + "Number of crypto contexts to preallocate"); + +static mempool_t *fscrypt_bounce_page_pool = NULL; + +static LIST_HEAD(fscrypt_free_ctxs); +static DEFINE_SPINLOCK(fscrypt_ctx_lock); + +static struct workqueue_struct *fscrypt_read_workqueue; +static DEFINE_MUTEX(fscrypt_init_mutex); + +static struct kmem_cache *fscrypt_ctx_cachep; +struct kmem_cache *fscrypt_info_cachep; + +/** + * fscrypt_release_ctx() - Releases an encryption context + * @ctx: The encryption context to release. + * + * If the encryption context was allocated from the pre-allocated pool, returns + * it to that pool. Else, frees it. + * + * If there's a bounce page in the context, this frees that. + */ +void fscrypt_release_ctx(struct fscrypt_ctx *ctx) +{ + unsigned long flags; + + if (ctx->flags & FS_WRITE_PATH_FL && ctx->w.bounce_page) { + mempool_free(ctx->w.bounce_page, fscrypt_bounce_page_pool); + ctx->w.bounce_page = NULL; + } + ctx->w.control_page = NULL; + if (ctx->flags & FS_CTX_REQUIRES_FREE_ENCRYPT_FL) { + kmem_cache_free(fscrypt_ctx_cachep, ctx); + } else { + spin_lock_irqsave(&fscrypt_ctx_lock, flags); + list_add(&ctx->free_list, &fscrypt_free_ctxs); + spin_unlock_irqrestore(&fscrypt_ctx_lock, flags); + } +} +EXPORT_SYMBOL(fscrypt_release_ctx); + +/** + * fscrypt_get_ctx() - Gets an encryption context + * @inode: The inode for which we are doing the crypto + * @gfp_flags: The gfp flag for memory allocation + * + * Allocates and initializes an encryption context. + * + * Return: An allocated and initialized encryption context on success; error + * value or NULL otherwise. + */ +struct fscrypt_ctx *fscrypt_get_ctx(struct inode *inode, gfp_t gfp_flags) +{ + struct fscrypt_ctx *ctx = NULL; + struct fscrypt_info *ci = inode->i_crypt_info; + unsigned long flags; + + if (ci == NULL) + return ERR_PTR(-ENOKEY); + + /* + * We first try getting the ctx from a free list because in + * the common case the ctx will have an allocated and + * initialized crypto tfm, so it's probably a worthwhile + * optimization. For the bounce page, we first try getting it + * from the kernel allocator because that's just about as fast + * as getting it from a list and because a cache of free pages + * should generally be a "last resort" option for a filesystem + * to be able to do its job. + */ + spin_lock_irqsave(&fscrypt_ctx_lock, flags); + ctx = list_first_entry_or_null(&fscrypt_free_ctxs, + struct fscrypt_ctx, free_list); + if (ctx) + list_del(&ctx->free_list); + spin_unlock_irqrestore(&fscrypt_ctx_lock, flags); + if (!ctx) { + ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, gfp_flags); + if (!ctx) + return ERR_PTR(-ENOMEM); + ctx->flags |= FS_CTX_REQUIRES_FREE_ENCRYPT_FL; + } else { + ctx->flags &= ~FS_CTX_REQUIRES_FREE_ENCRYPT_FL; + } + ctx->flags &= ~FS_WRITE_PATH_FL; + return ctx; +} +EXPORT_SYMBOL(fscrypt_get_ctx); + +/** + * fscrypt_complete() - The completion callback for page encryption + * @req: The asynchronous encryption request context + * @res: The result of the encryption operation + */ +static void fscrypt_complete(struct crypto_async_request *req, int res) +{ + struct fscrypt_completion_result *ecr = req->data; + + if (res == -EINPROGRESS) + return; + ecr->res = res; + complete(&ecr->completion); +} + +typedef enum { + FS_DECRYPT = 0, + FS_ENCRYPT, +} fscrypt_direction_t; + +static int do_page_crypto(struct inode *inode, + fscrypt_direction_t rw, pgoff_t index, + struct page *src_page, struct page *dest_page, + gfp_t gfp_flags) +{ + u8 xts_tweak[FS_XTS_TWEAK_SIZE]; + struct skcipher_request *req = NULL; + DECLARE_FS_COMPLETION_RESULT(ecr); + struct scatterlist dst, src; + struct fscrypt_info *ci = inode->i_crypt_info; + struct crypto_skcipher *tfm = ci->ci_ctfm; + int res = 0; + + req = skcipher_request_alloc(tfm, gfp_flags); + if (!req) { + printk_ratelimited(KERN_ERR + "%s: crypto_request_alloc() failed\n", + __func__); + return -ENOMEM; + } + + skcipher_request_set_callback( + req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, + fscrypt_complete, &ecr); + + BUILD_BUG_ON(FS_XTS_TWEAK_SIZE < sizeof(index)); + memcpy(xts_tweak, &index, sizeof(index)); + memset(&xts_tweak[sizeof(index)], 0, + FS_XTS_TWEAK_SIZE - sizeof(index)); + + sg_init_table(&dst, 1); + sg_set_page(&dst, dest_page, PAGE_SIZE, 0); + sg_init_table(&src, 1); + sg_set_page(&src, src_page, PAGE_SIZE, 0); + skcipher_request_set_crypt(req, &src, &dst, PAGE_SIZE, + xts_tweak); + if (rw == FS_DECRYPT) + res = crypto_skcipher_decrypt(req); + else + res = crypto_skcipher_encrypt(req); + if (res == -EINPROGRESS || res == -EBUSY) { + BUG_ON(req->base.data != &ecr); + wait_for_completion(&ecr.completion); + res = ecr.res; + } + skcipher_request_free(req); + if (res) { + printk_ratelimited(KERN_ERR + "%s: crypto_skcipher_encrypt() returned %d\n", + __func__, res); + return res; + } + return 0; +} + +static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx, gfp_t gfp_flags) +{ + ctx->w.bounce_page = mempool_alloc(fscrypt_bounce_page_pool, gfp_flags); + if (ctx->w.bounce_page == NULL) + return ERR_PTR(-ENOMEM); + ctx->flags |= FS_WRITE_PATH_FL; + return ctx->w.bounce_page; +} + +/** + * fscypt_encrypt_page() - Encrypts a page + * @inode: The inode for which the encryption should take place + * @plaintext_page: The page to encrypt. Must be locked. + * @gfp_flags: The gfp flag for memory allocation + * + * Allocates a ciphertext page and encrypts plaintext_page into it using the ctx + * encryption context. + * + * Called on the page write path. The caller must call + * fscrypt_restore_control_page() on the returned ciphertext page to + * release the bounce buffer and the encryption context. + * + * Return: An allocated page with the encrypted content on success. Else, an + * error value or NULL. + */ +struct page *fscrypt_encrypt_page(struct inode *inode, + struct page *plaintext_page, gfp_t gfp_flags) +{ + struct fscrypt_ctx *ctx; + struct page *ciphertext_page = NULL; + int err; + + BUG_ON(!PageLocked(plaintext_page)); + + ctx = fscrypt_get_ctx(inode, gfp_flags); + if (IS_ERR(ctx)) + return (struct page *)ctx; + + /* The encryption operation will require a bounce page. */ + ciphertext_page = alloc_bounce_page(ctx, gfp_flags); + if (IS_ERR(ciphertext_page)) + goto errout; + + ctx->w.control_page = plaintext_page; + err = do_page_crypto(inode, FS_ENCRYPT, plaintext_page->index, + plaintext_page, ciphertext_page, + gfp_flags); + if (err) { + ciphertext_page = ERR_PTR(err); + goto errout; + } + SetPagePrivate(ciphertext_page); + set_page_private(ciphertext_page, (unsigned long)ctx); + lock_page(ciphertext_page); + return ciphertext_page; + +errout: + fscrypt_release_ctx(ctx); + return ciphertext_page; +} +EXPORT_SYMBOL(fscrypt_encrypt_page); + +/** + * f2crypt_decrypt_page() - Decrypts a page in-place + * @page: The page to decrypt. Must be locked. + * + * Decrypts page in-place using the ctx encryption context. + * + * Called from the read completion callback. + * + * Return: Zero on success, non-zero otherwise. + */ +int fscrypt_decrypt_page(struct page *page) +{ + BUG_ON(!PageLocked(page)); + + return do_page_crypto(page->mapping->host, + FS_DECRYPT, page->index, page, page, GFP_NOFS); +} +EXPORT_SYMBOL(fscrypt_decrypt_page); + +int fscrypt_zeroout_range(struct inode *inode, pgoff_t lblk, + sector_t pblk, unsigned int len) +{ + struct fscrypt_ctx *ctx; + struct page *ciphertext_page = NULL; + struct bio *bio; + int ret, err = 0; + + BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE); + + ctx = fscrypt_get_ctx(inode, GFP_NOFS); + if (IS_ERR(ctx)) + return PTR_ERR(ctx); + + ciphertext_page = alloc_bounce_page(ctx, GFP_NOWAIT); + if (IS_ERR(ciphertext_page)) { + err = PTR_ERR(ciphertext_page); + goto errout; + } + + while (len--) { + err = do_page_crypto(inode, FS_ENCRYPT, lblk, + ZERO_PAGE(0), ciphertext_page, + GFP_NOFS); + if (err) + goto errout; + + bio = bio_alloc(GFP_NOWAIT, 1); + if (!bio) { + err = -ENOMEM; + goto errout; + } + bio->bi_bdev = inode->i_sb->s_bdev; + bio->bi_iter.bi_sector = + pblk << (inode->i_sb->s_blocksize_bits - 9); + ret = bio_add_page(bio, ciphertext_page, + inode->i_sb->s_blocksize, 0); + if (ret != inode->i_sb->s_blocksize) { + /* should never happen! */ + WARN_ON(1); + bio_put(bio); + err = -EIO; + goto errout; + } + err = submit_bio_wait(WRITE, bio); + if ((err == 0) && bio->bi_error) + err = -EIO; + bio_put(bio); + if (err) + goto errout; + lblk++; + pblk++; + } + err = 0; +errout: + fscrypt_release_ctx(ctx); + return err; +} +EXPORT_SYMBOL(fscrypt_zeroout_range); + +/* + * Validate dentries for encrypted directories to make sure we aren't + * potentially caching stale data after a key has been added or + * removed. + */ +static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags) +{ + struct dentry *dir; + struct fscrypt_info *ci; + int dir_has_key, cached_with_key; + + if (flags & LOOKUP_RCU) + return -ECHILD; + + dir = dget_parent(dentry); + if (!d_inode(dir)->i_sb->s_cop->is_encrypted(d_inode(dir))) { + dput(dir); + return 0; + } + + ci = d_inode(dir)->i_crypt_info; + if (ci && ci->ci_keyring_key && + (ci->ci_keyring_key->flags & ((1 << KEY_FLAG_INVALIDATED) | + (1 << KEY_FLAG_REVOKED) | + (1 << KEY_FLAG_DEAD)))) + ci = NULL; + + /* this should eventually be an flag in d_flags */ + spin_lock(&dentry->d_lock); + cached_with_key = dentry->d_flags & DCACHE_ENCRYPTED_WITH_KEY; + spin_unlock(&dentry->d_lock); + dir_has_key = (ci != NULL); + dput(dir); + + /* + * If the dentry was cached without the key, and it is a + * negative dentry, it might be a valid name. We can't check + * if the key has since been made available due to locking + * reasons, so we fail the validation so ext4_lookup() can do + * this check. + * + * We also fail the validation if the dentry was created with + * the key present, but we no longer have the key, or vice versa. + */ + if ((!cached_with_key && d_is_negative(dentry)) || + (!cached_with_key && dir_has_key) || + (cached_with_key && !dir_has_key)) + return 0; + return 1; +} + +const struct dentry_operations fscrypt_d_ops = { + .d_revalidate = fscrypt_d_revalidate, +}; +EXPORT_SYMBOL(fscrypt_d_ops); + +/* + * Call fscrypt_decrypt_page on every single page, reusing the encryption + * context. + */ +static void completion_pages(struct work_struct *work) +{ + struct fscrypt_ctx *ctx = + container_of(work, struct fscrypt_ctx, r.work); + struct bio *bio = ctx->r.bio; + struct bio_vec *bv; + int i; + + bio_for_each_segment_all(bv, bio, i) { + struct page *page = bv->bv_page; + int ret = fscrypt_decrypt_page(page); + + if (ret) { + WARN_ON_ONCE(1); + SetPageError(page); + } else { + SetPageUptodate(page); + } + unlock_page(page); + } + fscrypt_release_ctx(ctx); + bio_put(bio); +} + +void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *ctx, struct bio *bio) +{ + INIT_WORK(&ctx->r.work, completion_pages); + ctx->r.bio = bio; + queue_work(fscrypt_read_workqueue, &ctx->r.work); +} +EXPORT_SYMBOL(fscrypt_decrypt_bio_pages); + +void fscrypt_pullback_bio_page(struct page **page, bool restore) +{ + struct fscrypt_ctx *ctx; + struct page *bounce_page; + + /* The bounce data pages are unmapped. */ + if ((*page)->mapping) + return; + + /* The bounce data page is unmapped. */ + bounce_page = *page; + ctx = (struct fscrypt_ctx *)page_private(bounce_page); + + /* restore control page */ + *page = ctx->w.control_page; + + if (restore) + fscrypt_restore_control_page(bounce_page); +} +EXPORT_SYMBOL(fscrypt_pullback_bio_page); + +void fscrypt_restore_control_page(struct page *page) +{ + struct fscrypt_ctx *ctx; + + ctx = (struct fscrypt_ctx *)page_private(page); + set_page_private(page, (unsigned long)NULL); + ClearPagePrivate(page); + unlock_page(page); + fscrypt_release_ctx(ctx); +} +EXPORT_SYMBOL(fscrypt_restore_control_page); + +static void fscrypt_destroy(void) +{ + struct fscrypt_ctx *pos, *n; + + list_for_each_entry_safe(pos, n, &fscrypt_free_ctxs, free_list) + kmem_cache_free(fscrypt_ctx_cachep, pos); + INIT_LIST_HEAD(&fscrypt_free_ctxs); + mempool_destroy(fscrypt_bounce_page_pool); + fscrypt_bounce_page_pool = NULL; +} + +/** + * fscrypt_initialize() - allocate major buffers for fs encryption. + * + * We only call this when we start accessing encrypted files, since it + * results in memory getting allocated that wouldn't otherwise be used. + * + * Return: Zero on success, non-zero otherwise. + */ +int fscrypt_initialize(void) +{ + int i, res = -ENOMEM; + + if (fscrypt_bounce_page_pool) + return 0; + + mutex_lock(&fscrypt_init_mutex); + if (fscrypt_bounce_page_pool) + goto already_initialized; + + for (i = 0; i < num_prealloc_crypto_ctxs; i++) { + struct fscrypt_ctx *ctx; + + ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, GFP_NOFS); + if (!ctx) + goto fail; + list_add(&ctx->free_list, &fscrypt_free_ctxs); + } + + fscrypt_bounce_page_pool = + mempool_create_page_pool(num_prealloc_crypto_pages, 0); + if (!fscrypt_bounce_page_pool) + goto fail; + +already_initialized: + mutex_unlock(&fscrypt_init_mutex); + return 0; +fail: + fscrypt_destroy(); + mutex_unlock(&fscrypt_init_mutex); + return res; +} +EXPORT_SYMBOL(fscrypt_initialize); + +/** + * fscrypt_init() - Set up for fs encryption. + */ +static int __init fscrypt_init(void) +{ + fscrypt_read_workqueue = alloc_workqueue("fscrypt_read_queue", + WQ_HIGHPRI, 0); + if (!fscrypt_read_workqueue) + goto fail; + + fscrypt_ctx_cachep = KMEM_CACHE(fscrypt_ctx, SLAB_RECLAIM_ACCOUNT); + if (!fscrypt_ctx_cachep) + goto fail_free_queue; + + fscrypt_info_cachep = KMEM_CACHE(fscrypt_info, SLAB_RECLAIM_ACCOUNT); + if (!fscrypt_info_cachep) + goto fail_free_ctx; + + return 0; + +fail_free_ctx: + kmem_cache_destroy(fscrypt_ctx_cachep); +fail_free_queue: + destroy_workqueue(fscrypt_read_workqueue); +fail: + return -ENOMEM; +} +module_init(fscrypt_init) + +/** + * fscrypt_exit() - Shutdown the fs encryption system + */ +static void __exit fscrypt_exit(void) +{ + fscrypt_destroy(); + + if (fscrypt_read_workqueue) + destroy_workqueue(fscrypt_read_workqueue); + kmem_cache_destroy(fscrypt_ctx_cachep); + kmem_cache_destroy(fscrypt_info_cachep); +} +module_exit(fscrypt_exit); + +MODULE_LICENSE("GPL"); diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c new file mode 100644 index 000000000..5d6d49113 --- /dev/null +++ b/fs/crypto/fname.c @@ -0,0 +1,424 @@ +/* + * This contains functions for filename crypto management + * + * Copyright (C) 2015, Google, Inc. + * Copyright (C) 2015, Motorola Mobility + * + * Written by Uday Savagaonkar, 2014. + * Modified by Jaegeuk Kim, 2015. + * + * This has not yet undergone a rigorous security audit. + */ + +#include <keys/encrypted-type.h> +#include <keys/user-type.h> +#include <linux/scatterlist.h> +#include <linux/ratelimit.h> +#include <linux/fscrypto.h> + +static u32 size_round_up(size_t size, size_t blksize) +{ + return ((size + blksize - 1) / blksize) * blksize; +} + +/** + * dir_crypt_complete() - + */ +static void dir_crypt_complete(struct crypto_async_request *req, int res) +{ + struct fscrypt_completion_result *ecr = req->data; + + if (res == -EINPROGRESS) + return; + ecr->res = res; + complete(&ecr->completion); +} + +/** + * fname_encrypt() - + * + * This function encrypts the input filename, and returns the length of the + * ciphertext. Errors are returned as negative numbers. We trust the caller to + * allocate sufficient memory to oname string. + */ +static int fname_encrypt(struct inode *inode, + const struct qstr *iname, struct fscrypt_str *oname) +{ + u32 ciphertext_len; + struct skcipher_request *req = NULL; + DECLARE_FS_COMPLETION_RESULT(ecr); + struct fscrypt_info *ci = inode->i_crypt_info; + struct crypto_skcipher *tfm = ci->ci_ctfm; + int res = 0; + char iv[FS_CRYPTO_BLOCK_SIZE]; + struct scatterlist src_sg, dst_sg; + int padding = 4 << (ci->ci_flags & FS_POLICY_FLAGS_PAD_MASK); + char *workbuf, buf[32], *alloc_buf = NULL; + unsigned lim; + + lim = inode->i_sb->s_cop->max_namelen(inode); + if (iname->len <= 0 || iname->len > lim) + return -EIO; + + ciphertext_len = (iname->len < FS_CRYPTO_BLOCK_SIZE) ? + FS_CRYPTO_BLOCK_SIZE : iname->len; + ciphertext_len = size_round_up(ciphertext_len, padding); + ciphertext_len = (ciphertext_len > lim) ? lim : ciphertext_len; + + if (ciphertext_len <= sizeof(buf)) { + workbuf = buf; + } else { + alloc_buf = kmalloc(ciphertext_len, GFP_NOFS); + if (!alloc_buf) + return -ENOMEM; + workbuf = alloc_buf; + } + + /* Allocate request */ + req = skcipher_request_alloc(tfm, GFP_NOFS); + if (!req) { + printk_ratelimited(KERN_ERR + "%s: crypto_request_alloc() failed\n", __func__); + kfree(alloc_buf); + return -ENOMEM; + } + skcipher_request_set_callback(req, + CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, + dir_crypt_complete, &ecr); + + /* Copy the input */ + memcpy(workbuf, iname->name, iname->len); + if (iname->len < ciphertext_len) + memset(workbuf + iname->len, 0, ciphertext_len - iname->len); + + /* Initialize IV */ + memset(iv, 0, FS_CRYPTO_BLOCK_SIZE); + + /* Create encryption request */ + sg_init_one(&src_sg, workbuf, ciphertext_len); + sg_init_one(&dst_sg, oname->name, ciphertext_len); + skcipher_request_set_crypt(req, &src_sg, &dst_sg, ciphertext_len, iv); + res = crypto_skcipher_encrypt(req); + if (res == -EINPROGRESS || res == -EBUSY) { + wait_for_completion(&ecr.completion); + res = ecr.res; + } + kfree(alloc_buf); + skcipher_request_free(req); + if (res < 0) + printk_ratelimited(KERN_ERR + "%s: Error (error code %d)\n", __func__, res); + + oname->len = ciphertext_len; + return res; +} + +/* + * fname_decrypt() + * This function decrypts the input filename, and returns + * the length of the plaintext. + * Errors are returned as negative numbers. + * We trust the caller to allocate sufficient memory to oname string. + */ +static int fname_decrypt(struct inode *inode, + const struct fscrypt_str *iname, + struct fscrypt_str *oname) +{ + struct skcipher_request *req = NULL; + DECLARE_FS_COMPLETION_RESULT(ecr); + struct scatterlist src_sg, dst_sg; + struct fscrypt_info *ci = inode->i_crypt_info; + struct crypto_skcipher *tfm = ci->ci_ctfm; + int res = 0; + char iv[FS_CRYPTO_BLOCK_SIZE]; + unsigned lim; + + lim = inode->i_sb->s_cop->max_namelen(inode); + if (iname->len <= 0 || iname->len > lim) + return -EIO; + + /* Allocate request */ + req = skcipher_request_alloc(tfm, GFP_NOFS); + if (!req) { + printk_ratelimited(KERN_ERR + "%s: crypto_request_alloc() failed\n", __func__); + return -ENOMEM; + } + skcipher_request_set_callback(req, + CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, + dir_crypt_complete, &ecr); + + /* Initialize IV */ + memset(iv, 0, FS_CRYPTO_BLOCK_SIZE); + + /* Create decryption request */ + sg_init_one(&src_sg, iname->name, iname->len); + sg_init_one(&dst_sg, oname->name, oname->len); + skcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, iv); + res = crypto_skcipher_decrypt(req); + if (res == -EINPROGRESS || res == -EBUSY) { + wait_for_completion(&ecr.completion); + res = ecr.res; + } + skcipher_request_free(req); + if (res < 0) { + printk_ratelimited(KERN_ERR + "%s: Error (error code %d)\n", __func__, res); + return res; + } + + oname->len = strnlen(oname->name, iname->len); + return oname->len; +} + +static const char *lookup_table = + "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,"; + +/** + * digest_encode() - + * + * Encodes the input digest using characters from the set [a-zA-Z0-9_+]. + * The encoded string is roughly 4/3 times the size of the input string. + */ +static int digest_encode(const char *src, int len, char *dst) +{ + int i = 0, bits = 0, ac = 0; + char *cp = dst; + + while (i < len) { + ac += (((unsigned char) src[i]) << bits); + bits += 8; + do { + *cp++ = lookup_table[ac & 0x3f]; + ac >>= 6; + bits -= 6; + } while (bits >= 6); + i++; + } + if (bits) + *cp++ = lookup_table[ac & 0x3f]; + return cp - dst; +} + +static int digest_decode(const char *src, int len, char *dst) +{ + int i = 0, bits = 0, ac = 0; + const char *p; + char *cp = dst; + + while (i < len) { + p = strchr(lookup_table, src[i]); + if (p == NULL || src[i] == 0) + return -2; + ac += (p - lookup_table) << bits; + bits += 6; + if (bits >= 8) { + *cp++ = ac & 0xff; + ac >>= 8; + bits -= 8; + } + i++; + } + if (ac) + return -1; + return cp - dst; +} + +u32 fscrypt_fname_encrypted_size(struct inode *inode, u32 ilen) +{ + int padding = 32; + struct fscrypt_info *ci = inode->i_crypt_info; + + if (ci) + padding = 4 << (ci->ci_flags & FS_POLICY_FLAGS_PAD_MASK); + if (ilen < FS_CRYPTO_BLOCK_SIZE) + ilen = FS_CRYPTO_BLOCK_SIZE; + return size_round_up(ilen, padding); +} +EXPORT_SYMBOL(fscrypt_fname_encrypted_size); + +/** + * fscrypt_fname_crypto_alloc_obuff() - + * + * Allocates an output buffer that is sufficient for the crypto operation + * specified by the context and the direction. + */ +int fscrypt_fname_alloc_buffer(struct inode *inode, + u32 ilen, struct fscrypt_str *crypto_str) +{ + unsigned int olen = fscrypt_fname_encrypted_size(inode, ilen); + + crypto_str->len = olen; + if (olen < FS_FNAME_CRYPTO_DIGEST_SIZE * 2) + olen = FS_FNAME_CRYPTO_DIGEST_SIZE * 2; + /* + * Allocated buffer can hold one more character to null-terminate the + * string + */ + crypto_str->name = kmalloc(olen + 1, GFP_NOFS); + if (!(crypto_str->name)) + return -ENOMEM; + return 0; +} +EXPORT_SYMBOL(fscrypt_fname_alloc_buffer); + +/** + * fscrypt_fname_crypto_free_buffer() - + * + * Frees the buffer allocated for crypto operation. + */ +void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str) +{ + if (!crypto_str) + return; + kfree(crypto_str->name); + crypto_str->name = NULL; +} +EXPORT_SYMBOL(fscrypt_fname_free_buffer); + +/** + * fscrypt_fname_disk_to_usr() - converts a filename from disk space to user + * space + */ +int fscrypt_fname_disk_to_usr(struct inode *inode, + u32 hash, u32 minor_hash, + const struct fscrypt_str *iname, + struct fscrypt_str *oname) +{ + const struct qstr qname = FSTR_TO_QSTR(iname); + char buf[24]; + int ret; + + if (fscrypt_is_dot_dotdot(&qname)) { + oname->name[0] = '.'; + oname->name[iname->len - 1] = '.'; + oname->len = iname->len; + return oname->len; + } + + if (iname->len < FS_CRYPTO_BLOCK_SIZE) + return -EUCLEAN; + + if (inode->i_crypt_info) + return fname_decrypt(inode, iname, oname); + + if (iname->len <= FS_FNAME_CRYPTO_DIGEST_SIZE) { + ret = digest_encode(iname->name, iname->len, oname->name); + oname->len = ret; + return ret; + } + if (hash) { + memcpy(buf, &hash, 4); + memcpy(buf + 4, &minor_hash, 4); + } else { + memset(buf, 0, 8); + } + memcpy(buf + 8, iname->name + iname->len - 16, 16); + oname->name[0] = '_'; + ret = digest_encode(buf, 24, oname->name + 1); + oname->len = ret + 1; + return ret + 1; +} +EXPORT_SYMBOL(fscrypt_fname_disk_to_usr); + +/** + * fscrypt_fname_usr_to_disk() - converts a filename from user space to disk + * space + */ +int fscrypt_fname_usr_to_disk(struct inode *inode, + const struct qstr *iname, + struct fscrypt_str *oname) +{ + if (fscrypt_is_dot_dotdot(iname)) { + oname->name[0] = '.'; + oname->name[iname->len - 1] = '.'; + oname->len = iname->len; + return oname->len; + } + if (inode->i_crypt_info) + return fname_encrypt(inode, iname, oname); + /* + * Without a proper key, a user is not allowed to modify the filenames + * in a directory. Consequently, a user space name cannot be mapped to + * a disk-space name + */ + return -EACCES; +} +EXPORT_SYMBOL(fscrypt_fname_usr_to_disk); + +int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, + int lookup, struct fscrypt_name *fname) +{ + int ret = 0, bigname = 0; + + memset(fname, 0, sizeof(struct fscrypt_name)); + fname->usr_fname = iname; + + if (!dir->i_sb->s_cop->is_encrypted(dir) || + fscrypt_is_dot_dotdot(iname)) { + fname->disk_name.name = (unsigned char *)iname->name; + fname->disk_name.len = iname->len; + return 0; + } + ret = get_crypt_info(dir); + if (ret && ret != -EOPNOTSUPP) + return ret; + + if (dir->i_crypt_info) { + ret = fscrypt_fname_alloc_buffer(dir, iname->len, + &fname->crypto_buf); + if (ret < 0) + return ret; + ret = fname_encrypt(dir, iname, &fname->crypto_buf); + if (ret < 0) + goto errout; + fname->disk_name.name = fname->crypto_buf.name; + fname->disk_name.len = fname->crypto_buf.len; + return 0; + } + if (!lookup) + return -EACCES; + + /* + * We don't have the key and we are doing a lookup; decode the + * user-supplied name + */ + if (iname->name[0] == '_') + bigname = 1; + if ((bigname && (iname->len != 33)) || (!bigname && (iname->len > 43))) + return -ENOENT; + + fname->crypto_buf.name = kmalloc(32, GFP_KERNEL); + if (fname->crypto_buf.name == NULL) + return -ENOMEM; + + ret = digest_decode(iname->name + bigname, iname->len - bigname, + fname->crypto_buf.name); + if (ret < 0) { + ret = -ENOENT; + goto errout; + } + fname->crypto_buf.len = ret; + if (bigname) { + memcpy(&fname->hash, fname->crypto_buf.name, 4); + memcpy(&fname->minor_hash, fname->crypto_buf.name + 4, 4); + } else { + fname->disk_name.name = fname->crypto_buf.name; + fname->disk_name.len = fname->crypto_buf.len; + } + return 0; + +errout: + fscrypt_fname_free_buffer(&fname->crypto_buf); + return ret; +} +EXPORT_SYMBOL(fscrypt_setup_filename); + +void fscrypt_free_filename(struct fscrypt_name *fname) +{ + kfree(fname->crypto_buf.name); + fname->crypto_buf.name = NULL; + fname->usr_fname = NULL; + fname->disk_name.name = NULL; +} +EXPORT_SYMBOL(fscrypt_free_filename); diff --git a/fs/crypto/keyinfo.c b/fs/crypto/keyinfo.c new file mode 100644 index 000000000..1ac263edd --- /dev/null +++ b/fs/crypto/keyinfo.c @@ -0,0 +1,304 @@ +/* + * key management facility for FS encryption support. + * + * Copyright (C) 2015, Google, Inc. + * + * This contains encryption key functions. + * + * Written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar, 2015. + */ + +#include <keys/encrypted-type.h> +#include <keys/user-type.h> +#include <linux/random.h> +#include <linux/scatterlist.h> +#include <uapi/linux/keyctl.h> +#include <linux/fscrypto.h> + +static void derive_crypt_complete(struct crypto_async_request *req, int rc) +{ + struct fscrypt_completion_result *ecr = req->data; + + if (rc == -EINPROGRESS) + return; + + ecr->res = rc; + complete(&ecr->completion); +} + +/** + * derive_key_aes() - Derive a key using AES-128-ECB + * @deriving_key: Encryption key used for derivation. + * @source_key: Source key to which to apply derivation. + * @derived_key: Derived key. + * + * Return: Zero on success; non-zero otherwise. + */ +static int derive_key_aes(u8 deriving_key[FS_AES_128_ECB_KEY_SIZE], + u8 source_key[FS_AES_256_XTS_KEY_SIZE], + u8 derived_key[FS_AES_256_XTS_KEY_SIZE]) +{ + int res = 0; + struct skcipher_request *req = NULL; + DECLARE_FS_COMPLETION_RESULT(ecr); + struct scatterlist src_sg, dst_sg; + struct crypto_skcipher *tfm = crypto_alloc_skcipher("ecb(aes)", 0, 0); + + if (IS_ERR(tfm)) { + res = PTR_ERR(tfm); + tfm = NULL; + goto out; + } + crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_WEAK_KEY); + req = skcipher_request_alloc(tfm, GFP_NOFS); + if (!req) { + res = -ENOMEM; + goto out; + } + skcipher_request_set_callback(req, + CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, + derive_crypt_complete, &ecr); + res = crypto_skcipher_setkey(tfm, deriving_key, + FS_AES_128_ECB_KEY_SIZE); + if (res < 0) + goto out; + + sg_init_one(&src_sg, source_key, FS_AES_256_XTS_KEY_SIZE); + sg_init_one(&dst_sg, derived_key, FS_AES_256_XTS_KEY_SIZE); + skcipher_request_set_crypt(req, &src_sg, &dst_sg, + FS_AES_256_XTS_KEY_SIZE, NULL); + res = crypto_skcipher_encrypt(req); + if (res == -EINPROGRESS || res == -EBUSY) { + wait_for_completion(&ecr.completion); + res = ecr.res; + } +out: + skcipher_request_free(req); + crypto_free_skcipher(tfm); + return res; +} + +static int validate_user_key(struct fscrypt_info *crypt_info, + struct fscrypt_context *ctx, u8 *raw_key, + u8 *prefix, int prefix_size) +{ + u8 *full_key_descriptor; + struct key *keyring_key; + struct fscrypt_key *master_key; + const struct user_key_payload *ukp; + int full_key_len = prefix_size + (FS_KEY_DESCRIPTOR_SIZE * 2) + 1; + int res; + + full_key_descriptor = kmalloc(full_key_len, GFP_NOFS); + if (!full_key_descriptor) + return -ENOMEM; + + memcpy(full_key_descriptor, prefix, prefix_size); + sprintf(full_key_descriptor + prefix_size, + "%*phN", FS_KEY_DESCRIPTOR_SIZE, + ctx->master_key_descriptor); + full_key_descriptor[full_key_len - 1] = '\0'; + keyring_key = request_key(&key_type_logon, full_key_descriptor, NULL); + kfree(full_key_descriptor); + if (IS_ERR(keyring_key)) + return PTR_ERR(keyring_key); + + if (keyring_key->type != &key_type_logon) { + printk_once(KERN_WARNING + "%s: key type must be logon\n", __func__); + res = -ENOKEY; + goto out; + } + down_read(&keyring_key->sem); + ukp = user_key_payload(keyring_key); + if (ukp->datalen != sizeof(struct fscrypt_key)) { + res = -EINVAL; + up_read(&keyring_key->sem); + goto out; + } + master_key = (struct fscrypt_key *)ukp->data; + BUILD_BUG_ON(FS_AES_128_ECB_KEY_SIZE != FS_KEY_DERIVATION_NONCE_SIZE); + + if (master_key->size != FS_AES_256_XTS_KEY_SIZE) { + printk_once(KERN_WARNING + "%s: key size incorrect: %d\n", + __func__, master_key->size); + res = -ENOKEY; + up_read(&keyring_key->sem); + goto out; + } + res = derive_key_aes(ctx->nonce, master_key->raw, raw_key); + up_read(&keyring_key->sem); + if (res) + goto out; + + crypt_info->ci_keyring_key = keyring_key; + return 0; +out: + key_put(keyring_key); + return res; +} + +static void put_crypt_info(struct fscrypt_info *ci) +{ + if (!ci) + return; + + key_put(ci->ci_keyring_key); + crypto_free_skcipher(ci->ci_ctfm); + kmem_cache_free(fscrypt_info_cachep, ci); +} + +int get_crypt_info(struct inode *inode) +{ + struct fscrypt_info *crypt_info; + struct fscrypt_context ctx; + struct crypto_skcipher *ctfm; + const char *cipher_str; + u8 raw_key[FS_MAX_KEY_SIZE]; + u8 mode; + int res; + + res = fscrypt_initialize(); + if (res) + return res; + + if (!inode->i_sb->s_cop->get_context) + return -EOPNOTSUPP; +retry: + crypt_info = ACCESS_ONCE(inode->i_crypt_info); + if (crypt_info) { + if (!crypt_info->ci_keyring_key || + key_validate(crypt_info->ci_keyring_key) == 0) + return 0; + fscrypt_put_encryption_info(inode, crypt_info); + goto retry; + } + + res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx)); + if (res < 0) { + if (!fscrypt_dummy_context_enabled(inode)) + return res; + ctx.contents_encryption_mode = FS_ENCRYPTION_MODE_AES_256_XTS; + ctx.filenames_encryption_mode = FS_ENCRYPTION_MODE_AES_256_CTS; + ctx.flags = 0; + } else if (res != sizeof(ctx)) { + return -EINVAL; + } + res = 0; + + crypt_info = kmem_cache_alloc(fscrypt_info_cachep, GFP_NOFS); + if (!crypt_info) + return -ENOMEM; + + crypt_info->ci_flags = ctx.flags; + crypt_info->ci_data_mode = ctx.contents_encryption_mode; + crypt_info->ci_filename_mode = ctx.filenames_encryption_mode; + crypt_info->ci_ctfm = NULL; + crypt_info->ci_keyring_key = NULL; + memcpy(crypt_info->ci_master_key, ctx.master_key_descriptor, + sizeof(crypt_info->ci_master_key)); + if (S_ISREG(inode->i_mode)) + mode = crypt_info->ci_data_mode; + else if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)) + mode = crypt_info->ci_filename_mode; + else + BUG(); + + switch (mode) { + case FS_ENCRYPTION_MODE_AES_256_XTS: + cipher_str = "xts(aes)"; + break; + case FS_ENCRYPTION_MODE_AES_256_CTS: + cipher_str = "cts(cbc(aes))"; + break; + default: + printk_once(KERN_WARNING + "%s: unsupported key mode %d (ino %u)\n", + __func__, mode, (unsigned) inode->i_ino); + res = -ENOKEY; + goto out; + } + if (fscrypt_dummy_context_enabled(inode)) { + memset(raw_key, 0x42, FS_AES_256_XTS_KEY_SIZE); + goto got_key; + } + + res = validate_user_key(crypt_info, &ctx, raw_key, + FS_KEY_DESC_PREFIX, FS_KEY_DESC_PREFIX_SIZE); + if (res && inode->i_sb->s_cop->key_prefix) { + u8 *prefix = NULL; + int prefix_size, res2; + + prefix_size = inode->i_sb->s_cop->key_prefix(inode, &prefix); + res2 = validate_user_key(crypt_info, &ctx, raw_key, + prefix, prefix_size); + if (res2) { + if (res2 == -ENOKEY) + res = -ENOKEY; + goto out; + } + } else if (res) { + goto out; + } +got_key: + ctfm = crypto_alloc_skcipher(cipher_str, 0, 0); + if (!ctfm || IS_ERR(ctfm)) { + res = ctfm ? PTR_ERR(ctfm) : -ENOMEM; + printk(KERN_DEBUG + "%s: error %d (inode %u) allocating crypto tfm\n", + __func__, res, (unsigned) inode->i_ino); + goto out; + } + crypt_info->ci_ctfm = ctfm; + crypto_skcipher_clear_flags(ctfm, ~0); + crypto_skcipher_set_flags(ctfm, CRYPTO_TFM_REQ_WEAK_KEY); + res = crypto_skcipher_setkey(ctfm, raw_key, fscrypt_key_size(mode)); + if (res) + goto out; + + memzero_explicit(raw_key, sizeof(raw_key)); + if (cmpxchg(&inode->i_crypt_info, NULL, crypt_info) != NULL) { + put_crypt_info(crypt_info); + goto retry; + } + return 0; + +out: + if (res == -ENOKEY) + res = 0; + put_crypt_info(crypt_info); + memzero_explicit(raw_key, sizeof(raw_key)); + return res; +} + +void fscrypt_put_encryption_info(struct inode *inode, struct fscrypt_info *ci) +{ + struct fscrypt_info *prev; + + if (ci == NULL) + ci = ACCESS_ONCE(inode->i_crypt_info); + if (ci == NULL) + return; + + prev = cmpxchg(&inode->i_crypt_info, ci, NULL); + if (prev != ci) + return; + + put_crypt_info(ci); +} +EXPORT_SYMBOL(fscrypt_put_encryption_info); + +int fscrypt_get_encryption_info(struct inode *inode) +{ + struct fscrypt_info *ci = inode->i_crypt_info; + + if (!ci || + (ci->ci_keyring_key && + (ci->ci_keyring_key->flags & ((1 << KEY_FLAG_INVALIDATED) | + (1 << KEY_FLAG_REVOKED) | + (1 << KEY_FLAG_DEAD))))) + return get_crypt_info(inode); + return 0; +} +EXPORT_SYMBOL(fscrypt_get_encryption_info); diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c new file mode 100644 index 000000000..0f9961eed --- /dev/null +++ b/fs/crypto/policy.c @@ -0,0 +1,229 @@ +/* + * Encryption policy functions for per-file encryption support. + * + * Copyright (C) 2015, Google, Inc. + * Copyright (C) 2015, Motorola Mobility. + * + * Written by Michael Halcrow, 2015. + * Modified by Jaegeuk Kim, 2015. + */ + +#include <linux/random.h> +#include <linux/string.h> +#include <linux/fscrypto.h> + +static int inode_has_encryption_context(struct inode *inode) +{ + if (!inode->i_sb->s_cop->get_context) + return 0; + return (inode->i_sb->s_cop->get_context(inode, NULL, 0L) > 0); +} + +/* + * check whether the policy is consistent with the encryption context + * for the inode + */ +static int is_encryption_context_consistent_with_policy(struct inode *inode, + const struct fscrypt_policy *policy) +{ + struct fscrypt_context ctx; + int res; + + if (!inode->i_sb->s_cop->get_context) + return 0; + + res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx)); + if (res != sizeof(ctx)) + return 0; + + return (memcmp(ctx.master_key_descriptor, policy->master_key_descriptor, + FS_KEY_DESCRIPTOR_SIZE) == 0 && + (ctx.flags == policy->flags) && + (ctx.contents_encryption_mode == + policy->contents_encryption_mode) && + (ctx.filenames_encryption_mode == + policy->filenames_encryption_mode)); +} + +static int create_encryption_context_from_policy(struct inode *inode, + const struct fscrypt_policy *policy) +{ + struct fscrypt_context ctx; + int res; + + if (!inode->i_sb->s_cop->set_context) + return -EOPNOTSUPP; + + if (inode->i_sb->s_cop->prepare_context) { + res = inode->i_sb->s_cop->prepare_context(inode); + if (res) + return res; + } + + ctx.format = FS_ENCRYPTION_CONTEXT_FORMAT_V1; + memcpy(ctx.master_key_descriptor, policy->master_key_descriptor, + FS_KEY_DESCRIPTOR_SIZE); + + if (!fscrypt_valid_contents_enc_mode( + policy->contents_encryption_mode)) { + printk(KERN_WARNING + "%s: Invalid contents encryption mode %d\n", __func__, + policy->contents_encryption_mode); + return -EINVAL; + } + + if (!fscrypt_valid_filenames_enc_mode( + policy->filenames_encryption_mode)) { + printk(KERN_WARNING + "%s: Invalid filenames encryption mode %d\n", __func__, + policy->filenames_encryption_mode); + return -EINVAL; + } + + if (policy->flags & ~FS_POLICY_FLAGS_VALID) + return -EINVAL; + + ctx.contents_encryption_mode = policy->contents_encryption_mode; + ctx.filenames_encryption_mode = policy->filenames_encryption_mode; + ctx.flags = policy->flags; + BUILD_BUG_ON(sizeof(ctx.nonce) != FS_KEY_DERIVATION_NONCE_SIZE); + get_random_bytes(ctx.nonce, FS_KEY_DERIVATION_NONCE_SIZE); + + return inode->i_sb->s_cop->set_context(inode, &ctx, sizeof(ctx), NULL); +} + +int fscrypt_process_policy(struct inode *inode, + const struct fscrypt_policy *policy) +{ + if (policy->version != 0) + return -EINVAL; + + if (!inode_has_encryption_context(inode)) { + if (!inode->i_sb->s_cop->empty_dir) + return -EOPNOTSUPP; + if (!inode->i_sb->s_cop->empty_dir(inode)) + return -ENOTEMPTY; + return create_encryption_context_from_policy(inode, policy); + } + + if (is_encryption_context_consistent_with_policy(inode, policy)) + return 0; + + printk(KERN_WARNING "%s: Policy inconsistent with encryption context\n", + __func__); + return -EINVAL; +} +EXPORT_SYMBOL(fscrypt_process_policy); + +int fscrypt_get_policy(struct inode *inode, struct fscrypt_policy *policy) +{ + struct fscrypt_context ctx; + int res; + + if (!inode->i_sb->s_cop->get_context || + !inode->i_sb->s_cop->is_encrypted(inode)) + return -ENODATA; + + res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx)); + if (res != sizeof(ctx)) + return -ENODATA; + if (ctx.format != FS_ENCRYPTION_CONTEXT_FORMAT_V1) + return -EINVAL; + + policy->version = 0; + policy->contents_encryption_mode = ctx.contents_encryption_mode; + policy->filenames_encryption_mode = ctx.filenames_encryption_mode; + policy->flags = ctx.flags; + memcpy(&policy->master_key_descriptor, ctx.master_key_descriptor, + FS_KEY_DESCRIPTOR_SIZE); + return 0; +} +EXPORT_SYMBOL(fscrypt_get_policy); + +int fscrypt_has_permitted_context(struct inode *parent, struct inode *child) +{ + struct fscrypt_info *parent_ci, *child_ci; + int res; + + if ((parent == NULL) || (child == NULL)) { + printk(KERN_ERR "parent %p child %p\n", parent, child); + BUG_ON(1); + } + + /* no restrictions if the parent directory is not encrypted */ + if (!parent->i_sb->s_cop->is_encrypted(parent)) + return 1; + /* if the child directory is not encrypted, this is always a problem */ + if (!parent->i_sb->s_cop->is_encrypted(child)) + return 0; + res = fscrypt_get_encryption_info(parent); + if (res) + return 0; + res = fscrypt_get_encryption_info(child); + if (res) + return 0; + parent_ci = parent->i_crypt_info; + child_ci = child->i_crypt_info; + if (!parent_ci && !child_ci) + return 1; + if (!parent_ci || !child_ci) + return 0; + + return (memcmp(parent_ci->ci_master_key, + child_ci->ci_master_key, + FS_KEY_DESCRIPTOR_SIZE) == 0 && + (parent_ci->ci_data_mode == child_ci->ci_data_mode) && + (parent_ci->ci_filename_mode == child_ci->ci_filename_mode) && + (parent_ci->ci_flags == child_ci->ci_flags)); +} +EXPORT_SYMBOL(fscrypt_has_permitted_context); + +/** + * fscrypt_inherit_context() - Sets a child context from its parent + * @parent: Parent inode from which the context is inherited. + * @child: Child inode that inherits the context from @parent. + * @fs_data: private data given by FS. + * @preload: preload child i_crypt_info + * + * Return: Zero on success, non-zero otherwise + */ +int fscrypt_inherit_context(struct inode *parent, struct inode *child, + void *fs_data, bool preload) +{ + struct fscrypt_context ctx; + struct fscrypt_info *ci; + int res; + + if (!parent->i_sb->s_cop->set_context) + return -EOPNOTSUPP; + + res = fscrypt_get_encryption_info(parent); + if (res < 0) + return res; + + ci = parent->i_crypt_info; + if (ci == NULL) + return -ENOKEY; + + ctx.format = FS_ENCRYPTION_CONTEXT_FORMAT_V1; + if (fscrypt_dummy_context_enabled(parent)) { + ctx.contents_encryption_mode = FS_ENCRYPTION_MODE_AES_256_XTS; + ctx.filenames_encryption_mode = FS_ENCRYPTION_MODE_AES_256_CTS; + ctx.flags = 0; + memset(ctx.master_key_descriptor, 0x42, FS_KEY_DESCRIPTOR_SIZE); + res = 0; + } else { + ctx.contents_encryption_mode = ci->ci_data_mode; + ctx.filenames_encryption_mode = ci->ci_filename_mode; + ctx.flags = ci->ci_flags; + memcpy(ctx.master_key_descriptor, ci->ci_master_key, + FS_KEY_DESCRIPTOR_SIZE); + } + get_random_bytes(ctx.nonce, FS_KEY_DERIVATION_NONCE_SIZE); + res = parent->i_sb->s_cop->set_context(child, &ctx, + sizeof(ctx), fs_data); + if (res) + return res; + return preload ? fscrypt_get_encryption_info(child): 0; +} +EXPORT_SYMBOL(fscrypt_inherit_context); |