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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-23 13:28:57 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-23 13:28:57 -0700 |
| commit | 4352b8aee98005853aa63f57d6377282de17a33f (patch) | |
| tree | 27614d7a9ef05c32d089004e104364ce42324837 /Documentation/crypto/api-samples.rst | |
| download | linux-stable-4352b8aee98005853aa63f57d6377282de17a33f.tar.gz linux-stable-4352b8aee98005853aa63f57d6377282de17a33f.zip | |
Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linuxgrafted
Pull I3C updates from Alexandre Belloni:
"A new driver this cycle, for the AMD AXI I3C controller.
There are also new features such as IBI wakeup support, SETAASA device
discovery and ACPI support for the the DAA methods, meaning we can now
communicate with the SPD devices on DDR5 modules.
New driver:
- AMD AXI I3C master controller
Subsystem:
- I3C Common Command Code (CCC) handling improvements, especially
around GET CCCs
- SETAASA device discovery support
- ACPI support for all existing DAA methods like SETDASA, SETNEWDA as
well as I2C devices on I3C bus
- IBI-based wakeup support
Drivers:
- dw: SETAASA support
- mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C
controller support, PIO queue management support for HCI v1.2
- renesas: improve suspend to RAM support, add runtime PM support"
* tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits)
i3c: dw: reduce do_daa time if there's no client
i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller
i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2
i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode
i3c: dw: rename "pclk" to "apb" to match dt-binding
i3c: dw: make struct dw_i3c_cmd smaller
i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding
i3c: renesas: Don't register devices when ENTDAA times out
i3c: master: dw-i3c-master: fix OD timing for first broadcast
i3c: mipi-i3c-hci: Advertise IBI wakeup capability
i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev()
i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI
i3c: master: Reject IBI requests from non-IBI-capable devices
i3c: master: Add helper to query bus wakeup requirements
i3c: master: Report wakeup events for IBIs
i3c: master: Support IBI-based wakeup capability
i3c: master: Fix potential UAF in i3c_device_match()
i3c: master: Fix potential UAF in i3c_device_uevent()
i3c: Make dev->desc locking assumptions explicit
i3c: master: Fix use-after-free of master->this
...
Diffstat (limited to 'Documentation/crypto/api-samples.rst')
| -rw-r--r-- | Documentation/crypto/api-samples.rst | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/Documentation/crypto/api-samples.rst b/Documentation/crypto/api-samples.rst new file mode 100644 index 000000000..388bb7d7a --- /dev/null +++ b/Documentation/crypto/api-samples.rst @@ -0,0 +1,187 @@ +Code Examples +============= + +Code Example For Symmetric Key Cipher Operation +----------------------------------------------- + +This code encrypts some data with AES-256-XTS. For sake of example, +all inputs are random bytes, the encryption is done in-place, and it's +assumed the code is running in a context where it can sleep. + +:: + + static int test_skcipher(void) + { + struct crypto_skcipher *tfm = NULL; + struct skcipher_request *req = NULL; + u8 *data = NULL; + const size_t datasize = 512; /* data size in bytes */ + struct scatterlist sg; + DECLARE_CRYPTO_WAIT(wait); + u8 iv[16]; /* AES-256-XTS takes a 16-byte IV */ + u8 key[64]; /* AES-256-XTS takes a 64-byte key */ + int err; + + /* + * Allocate a tfm (a transformation object) and set the key. + * + * In real-world use, a tfm and key are typically used for many + * encryption/decryption operations. But in this example, we'll just do a + * single encryption operation with it (which is not very efficient). + */ + + tfm = crypto_alloc_skcipher("xts(aes)", 0, 0); + if (IS_ERR(tfm)) { + pr_err("Error allocating xts(aes) handle: %ld\n", PTR_ERR(tfm)); + return PTR_ERR(tfm); + } + + get_random_bytes(key, sizeof(key)); + err = crypto_skcipher_setkey(tfm, key, sizeof(key)); + if (err) { + pr_err("Error setting key: %d\n", err); + goto out; + } + + /* Allocate a request object */ + req = skcipher_request_alloc(tfm, GFP_KERNEL); + if (!req) { + err = -ENOMEM; + goto out; + } + + /* Prepare the input data */ + data = kmalloc(datasize, GFP_KERNEL); + if (!data) { + err = -ENOMEM; + goto out; + } + get_random_bytes(data, datasize); + + /* Initialize the IV */ + get_random_bytes(iv, sizeof(iv)); + + /* + * Encrypt the data in-place. + * + * For simplicity, in this example we wait for the request to complete + * before proceeding, even if the underlying implementation is asynchronous. + * + * To decrypt instead of encrypt, just change crypto_skcipher_encrypt() to + * crypto_skcipher_decrypt(). + */ + sg_init_one(&sg, data, datasize); + skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG | + CRYPTO_TFM_REQ_MAY_SLEEP, + crypto_req_done, &wait); + skcipher_request_set_crypt(req, &sg, &sg, datasize, iv); + err = crypto_wait_req(crypto_skcipher_encrypt(req), &wait); + if (err) { + pr_err("Error encrypting data: %d\n", err); + goto out; + } + + pr_debug("Encryption was successful\n"); + out: + crypto_free_skcipher(tfm); + skcipher_request_free(req); + kfree(data); + return err; + } + + +Code Example For Use of Operational State Memory With SHASH +----------------------------------------------------------- + +:: + + + struct sdesc { + struct shash_desc shash; + char ctx[]; + }; + + static struct sdesc *init_sdesc(struct crypto_shash *alg) + { + struct sdesc *sdesc; + int size; + + size = sizeof(struct shash_desc) + crypto_shash_descsize(alg); + sdesc = kmalloc(size, GFP_KERNEL); + if (!sdesc) + return ERR_PTR(-ENOMEM); + sdesc->shash.tfm = alg; + return sdesc; + } + + static int calc_hash(struct crypto_shash *alg, + const unsigned char *data, unsigned int datalen, + unsigned char *digest) + { + struct sdesc *sdesc; + int ret; + + sdesc = init_sdesc(alg); + if (IS_ERR(sdesc)) { + pr_info("can't alloc sdesc\n"); + return PTR_ERR(sdesc); + } + + ret = crypto_shash_digest(&sdesc->shash, data, datalen, digest); + kfree(sdesc); + return ret; + } + + static int test_hash(const unsigned char *data, unsigned int datalen, + unsigned char *digest) + { + struct crypto_shash *alg; + char *hash_alg_name = "sha1-padlock-nano"; + int ret; + + alg = crypto_alloc_shash(hash_alg_name, 0, 0); + if (IS_ERR(alg)) { + pr_info("can't alloc alg %s\n", hash_alg_name); + return PTR_ERR(alg); + } + ret = calc_hash(alg, data, datalen, digest); + crypto_free_shash(alg); + return ret; + } + + +Code Example For Random Number Generator Usage +---------------------------------------------- + +:: + + + static int get_random_numbers(u8 *buf, unsigned int len) + { + struct crypto_rng *rng = NULL; + char *drbg = "stdrng"; + int ret; + + if (!buf || !len) { + pr_debug("No output buffer provided\n"); + return -EINVAL; + } + + rng = crypto_alloc_rng(drbg, 0, 0); + if (IS_ERR(rng)) { + pr_debug("could not allocate RNG handle for %s\n", drbg); + return PTR_ERR(rng); + } + + ret = crypto_rng_get_bytes(rng, buf, len); + if (ret < 0) + pr_debug("generation of random numbers failed\n"); + else if (ret == 0) + pr_debug("RNG returned no data"); + else + pr_debug("RNG returned %d bytes of data\n", ret); + + out: + crypto_free_rng(rng); + return ret; + } |
