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Subject[PATCH 4.19 176/271] crypto: chacha20poly1305 - fix atomic sleep when using async algorithm
Date
From: Eric Biggers <ebiggers@google.com>

commit 7545b6c2087f4ef0287c8c9b7eba6a728c67ff8e upstream.

Clear the CRYPTO_TFM_REQ_MAY_SLEEP flag when the chacha20poly1305
operation is being continued from an async completion callback, since
sleeping may not be allowed in that context.

This is basically the same bug that was recently fixed in the xts and
lrw templates. But, it's always been broken in chacha20poly1305 too.
This was found using syzkaller in combination with the updated crypto
self-tests which actually test the MAY_SLEEP flag now.

Reproducer:

python -c 'import socket; socket.socket(socket.AF_ALG, 5, 0).bind(
("aead", "rfc7539(cryptd(chacha20-generic),poly1305-generic)"))'

Kernel output:

BUG: sleeping function called from invalid context at include/crypto/algapi.h:426
in_atomic(): 1, irqs_disabled(): 0, pid: 1001, name: kworker/2:2
[...]
CPU: 2 PID: 1001 Comm: kworker/2:2 Not tainted 5.2.0-rc2 #5
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-20181126_142135-anatol 04/01/2014
Workqueue: crypto cryptd_queue_worker
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x4d/0x6a lib/dump_stack.c:113
___might_sleep kernel/sched/core.c:6138 [inline]
___might_sleep.cold.19+0x8e/0x9f kernel/sched/core.c:6095
crypto_yield include/crypto/algapi.h:426 [inline]
crypto_hash_walk_done+0xd6/0x100 crypto/ahash.c:113
shash_ahash_update+0x41/0x60 crypto/shash.c:251
shash_async_update+0xd/0x10 crypto/shash.c:260
crypto_ahash_update include/crypto/hash.h:539 [inline]
poly_setkey+0xf6/0x130 crypto/chacha20poly1305.c:337
poly_init+0x51/0x60 crypto/chacha20poly1305.c:364
async_done_continue crypto/chacha20poly1305.c:78 [inline]
poly_genkey_done+0x15/0x30 crypto/chacha20poly1305.c:369
cryptd_skcipher_complete+0x29/0x70 crypto/cryptd.c:279
cryptd_skcipher_decrypt+0xcd/0x110 crypto/cryptd.c:339
cryptd_queue_worker+0x70/0xa0 crypto/cryptd.c:184
process_one_work+0x1ed/0x420 kernel/workqueue.c:2269
worker_thread+0x3e/0x3a0 kernel/workqueue.c:2415
kthread+0x11f/0x140 kernel/kthread.c:255
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

Fixes: 71ebc4d1b27d ("crypto: chacha20poly1305 - Add a ChaCha20-Poly1305 AEAD construction, RFC7539")
Cc: <stable@vger.kernel.org> # v4.2+
Cc: Martin Willi <martin@strongswan.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
crypto/chacha20poly1305.c | 30 +++++++++++++++++++-----------
1 file changed, 19 insertions(+), 11 deletions(-)

--- a/crypto/chacha20poly1305.c
+++ b/crypto/chacha20poly1305.c
@@ -67,6 +67,8 @@ struct chachapoly_req_ctx {
unsigned int cryptlen;
/* Actual AD, excluding IV */
unsigned int assoclen;
+ /* request flags, with MAY_SLEEP cleared if needed */
+ u32 flags;
union {
struct poly_req poly;
struct chacha_req chacha;
@@ -76,8 +78,12 @@ struct chachapoly_req_ctx {
static inline void async_done_continue(struct aead_request *req, int err,
int (*cont)(struct aead_request *))
{
- if (!err)
+ if (!err) {
+ struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
+
+ rctx->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
err = cont(req);
+ }

if (err != -EINPROGRESS && err != -EBUSY)
aead_request_complete(req, err);
@@ -144,7 +150,7 @@ static int chacha_decrypt(struct aead_re
dst = scatterwalk_ffwd(rctx->dst, req->dst, req->assoclen);
}

- skcipher_request_set_callback(&creq->req, aead_request_flags(req),
+ skcipher_request_set_callback(&creq->req, rctx->flags,
chacha_decrypt_done, req);
skcipher_request_set_tfm(&creq->req, ctx->chacha);
skcipher_request_set_crypt(&creq->req, src, dst,
@@ -188,7 +194,7 @@ static int poly_tail(struct aead_request
memcpy(&preq->tail.cryptlen, &len, sizeof(len));
sg_set_buf(preq->src, &preq->tail, sizeof(preq->tail));

- ahash_request_set_callback(&preq->req, aead_request_flags(req),
+ ahash_request_set_callback(&preq->req, rctx->flags,
poly_tail_done, req);
ahash_request_set_tfm(&preq->req, ctx->poly);
ahash_request_set_crypt(&preq->req, preq->src,
@@ -219,7 +225,7 @@ static int poly_cipherpad(struct aead_re
sg_init_table(preq->src, 1);
sg_set_buf(preq->src, &preq->pad, padlen);

- ahash_request_set_callback(&preq->req, aead_request_flags(req),
+ ahash_request_set_callback(&preq->req, rctx->flags,
poly_cipherpad_done, req);
ahash_request_set_tfm(&preq->req, ctx->poly);
ahash_request_set_crypt(&preq->req, preq->src, NULL, padlen);
@@ -250,7 +256,7 @@ static int poly_cipher(struct aead_reque
sg_init_table(rctx->src, 2);
crypt = scatterwalk_ffwd(rctx->src, crypt, req->assoclen);

- ahash_request_set_callback(&preq->req, aead_request_flags(req),
+ ahash_request_set_callback(&preq->req, rctx->flags,
poly_cipher_done, req);
ahash_request_set_tfm(&preq->req, ctx->poly);
ahash_request_set_crypt(&preq->req, crypt, NULL, rctx->cryptlen);
@@ -280,7 +286,7 @@ static int poly_adpad(struct aead_reques
sg_init_table(preq->src, 1);
sg_set_buf(preq->src, preq->pad, padlen);

- ahash_request_set_callback(&preq->req, aead_request_flags(req),
+ ahash_request_set_callback(&preq->req, rctx->flags,
poly_adpad_done, req);
ahash_request_set_tfm(&preq->req, ctx->poly);
ahash_request_set_crypt(&preq->req, preq->src, NULL, padlen);
@@ -304,7 +310,7 @@ static int poly_ad(struct aead_request *
struct poly_req *preq = &rctx->u.poly;
int err;

- ahash_request_set_callback(&preq->req, aead_request_flags(req),
+ ahash_request_set_callback(&preq->req, rctx->flags,
poly_ad_done, req);
ahash_request_set_tfm(&preq->req, ctx->poly);
ahash_request_set_crypt(&preq->req, req->src, NULL, rctx->assoclen);
@@ -331,7 +337,7 @@ static int poly_setkey(struct aead_reque
sg_init_table(preq->src, 1);
sg_set_buf(preq->src, rctx->key, sizeof(rctx->key));

- ahash_request_set_callback(&preq->req, aead_request_flags(req),
+ ahash_request_set_callback(&preq->req, rctx->flags,
poly_setkey_done, req);
ahash_request_set_tfm(&preq->req, ctx->poly);
ahash_request_set_crypt(&preq->req, preq->src, NULL, sizeof(rctx->key));
@@ -355,7 +361,7 @@ static int poly_init(struct aead_request
struct poly_req *preq = &rctx->u.poly;
int err;

- ahash_request_set_callback(&preq->req, aead_request_flags(req),
+ ahash_request_set_callback(&preq->req, rctx->flags,
poly_init_done, req);
ahash_request_set_tfm(&preq->req, ctx->poly);

@@ -393,7 +399,7 @@ static int poly_genkey(struct aead_reque

chacha_iv(creq->iv, req, 0);

- skcipher_request_set_callback(&creq->req, aead_request_flags(req),
+ skcipher_request_set_callback(&creq->req, rctx->flags,
poly_genkey_done, req);
skcipher_request_set_tfm(&creq->req, ctx->chacha);
skcipher_request_set_crypt(&creq->req, creq->src, creq->src,
@@ -433,7 +439,7 @@ static int chacha_encrypt(struct aead_re
dst = scatterwalk_ffwd(rctx->dst, req->dst, req->assoclen);
}

- skcipher_request_set_callback(&creq->req, aead_request_flags(req),
+ skcipher_request_set_callback(&creq->req, rctx->flags,
chacha_encrypt_done, req);
skcipher_request_set_tfm(&creq->req, ctx->chacha);
skcipher_request_set_crypt(&creq->req, src, dst,
@@ -451,6 +457,7 @@ static int chachapoly_encrypt(struct aea
struct chachapoly_req_ctx *rctx = aead_request_ctx(req);

rctx->cryptlen = req->cryptlen;
+ rctx->flags = aead_request_flags(req);

/* encrypt call chain:
* - chacha_encrypt/done()
@@ -472,6 +479,7 @@ static int chachapoly_decrypt(struct aea
struct chachapoly_req_ctx *rctx = aead_request_ctx(req);

rctx->cryptlen = req->cryptlen - POLY1305_DIGEST_SIZE;
+ rctx->flags = aead_request_flags(req);

/* decrypt call chain:
* - poly_genkey/done()

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