Message ID | f4a63091203d09e275c3df983692b630ffca4bca.1695921657.git.lukas@wunner.de |
---|---|
State | Superseded |
Headers | show |
Series | PCI device authentication | expand |
On Thu, 28 Sep 2023 19:32:35 +0200 Lukas Wunner <lukas@wunner.de> wrote: > Currently only a single default signature encoding is supported per > akcipher. > > A subsequent commit will allow a second encoding for ecdsa, namely P1363 > alternatively to X9.62. > > To accommodate for that, amend struct akcipher_request and struct > crypto_akcipher_sync_data to store the desired signature encoding for > verify and sign ops. > > Amend akcipher_request_set_crypt(), crypto_sig_verify() and > crypto_sig_sign() with an additional parameter which specifies the > desired signature encoding. Adjust all callers. > > Signed-off-by: Lukas Wunner <lukas@wunner.de> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > --- > crypto/akcipher.c | 2 +- > crypto/asymmetric_keys/public_key.c | 4 ++-- > crypto/internal.h | 1 + > crypto/rsa-pkcs1pad.c | 11 +++++++---- > crypto/sig.c | 6 ++++-- > crypto/testmgr.c | 8 +++++--- > crypto/testmgr.h | 1 + > include/crypto/akcipher.h | 10 +++++++++- > include/crypto/sig.h | 6 ++++-- > 9 files changed, 34 insertions(+), 15 deletions(-) > > diff --git a/crypto/akcipher.c b/crypto/akcipher.c > index 52813f0b19e4..88501c0886d2 100644 > --- a/crypto/akcipher.c > +++ b/crypto/akcipher.c > @@ -221,7 +221,7 @@ int crypto_akcipher_sync_prep(struct crypto_akcipher_sync_data *data) > sg = &data->sg; > sg_init_one(sg, buf, mlen); > akcipher_request_set_crypt(req, sg, data->dst ? sg : NULL, > - data->slen, data->dlen); > + data->slen, data->dlen, data->enc); > > crypto_init_wait(&data->cwait); > akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, > diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c > index abeecb8329b3..7f96e8e501db 100644 > --- a/crypto/asymmetric_keys/public_key.c > +++ b/crypto/asymmetric_keys/public_key.c > @@ -354,7 +354,7 @@ static int software_key_eds_op(struct kernel_pkey_params *params, > if (!issig) > break; > ret = crypto_sig_sign(sig, in, params->in_len, > - out, params->out_len); > + out, params->out_len, params->encoding); > break; > default: > BUG(); > @@ -438,7 +438,7 @@ int public_key_verify_signature(const struct public_key *pkey, > goto error_free_key; > > ret = crypto_sig_verify(tfm, sig->s, sig->s_size, > - sig->digest, sig->digest_size); > + sig->digest, sig->digest_size, sig->encoding); > > error_free_key: > kfree_sensitive(key); > diff --git a/crypto/internal.h b/crypto/internal.h > index 63e59240d5fb..268315b13ccd 100644 > --- a/crypto/internal.h > +++ b/crypto/internal.h > @@ -41,6 +41,7 @@ struct crypto_akcipher_sync_data { > void *dst; > unsigned int slen; > unsigned int dlen; > + const char *enc; > > struct akcipher_request *req; > struct crypto_wait cwait; > diff --git a/crypto/rsa-pkcs1pad.c b/crypto/rsa-pkcs1pad.c > index d2e5e104f8cf..5f9313a3b01e 100644 > --- a/crypto/rsa-pkcs1pad.c > +++ b/crypto/rsa-pkcs1pad.c > @@ -262,7 +262,8 @@ static int pkcs1pad_encrypt(struct akcipher_request *req) > > /* Reuse output buffer */ > akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg, > - req->dst, ctx->key_size - 1, req->dst_len); > + req->dst, ctx->key_size - 1, req->dst_len, > + NULL); > > err = crypto_akcipher_encrypt(&req_ctx->child_req); > if (err != -EINPROGRESS && err != -EBUSY) > @@ -362,7 +363,7 @@ static int pkcs1pad_decrypt(struct akcipher_request *req) > /* Reuse input buffer, output to a new buffer */ > akcipher_request_set_crypt(&req_ctx->child_req, req->src, > req_ctx->out_sg, req->src_len, > - ctx->key_size); > + ctx->key_size, NULL); > > err = crypto_akcipher_decrypt(&req_ctx->child_req); > if (err != -EINPROGRESS && err != -EBUSY) > @@ -419,7 +420,8 @@ static int pkcs1pad_sign(struct akcipher_request *req) > > /* Reuse output buffer */ > akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg, > - req->dst, ctx->key_size - 1, req->dst_len); > + req->dst, ctx->key_size - 1, req->dst_len, > + req->enc); > > err = crypto_akcipher_decrypt(&req_ctx->child_req); > if (err != -EINPROGRESS && err != -EBUSY) > @@ -551,7 +553,8 @@ static int pkcs1pad_verify(struct akcipher_request *req) > > /* Reuse input buffer, output to a new buffer */ > akcipher_request_set_crypt(&req_ctx->child_req, req->src, > - req_ctx->out_sg, sig_size, ctx->key_size); > + req_ctx->out_sg, sig_size, ctx->key_size, > + req->enc); > > err = crypto_akcipher_encrypt(&req_ctx->child_req); > if (err != -EINPROGRESS && err != -EBUSY) > diff --git a/crypto/sig.c b/crypto/sig.c > index 224c47019297..4fc1a8f865e4 100644 > --- a/crypto/sig.c > +++ b/crypto/sig.c > @@ -89,7 +89,7 @@ EXPORT_SYMBOL_GPL(crypto_sig_maxsize); > > int crypto_sig_sign(struct crypto_sig *tfm, > const void *src, unsigned int slen, > - void *dst, unsigned int dlen) > + void *dst, unsigned int dlen, const char *enc) > { > struct crypto_akcipher **ctx = crypto_sig_ctx(tfm); > struct crypto_akcipher_sync_data data = { > @@ -98,6 +98,7 @@ int crypto_sig_sign(struct crypto_sig *tfm, > .dst = dst, > .slen = slen, > .dlen = dlen, > + .enc = enc, > }; > > return crypto_akcipher_sync_prep(&data) ?: > @@ -108,7 +109,7 @@ EXPORT_SYMBOL_GPL(crypto_sig_sign); > > int crypto_sig_verify(struct crypto_sig *tfm, > const void *src, unsigned int slen, > - const void *digest, unsigned int dlen) > + const void *digest, unsigned int dlen, const char *enc) > { > struct crypto_akcipher **ctx = crypto_sig_ctx(tfm); > struct crypto_akcipher_sync_data data = { > @@ -116,6 +117,7 @@ int crypto_sig_verify(struct crypto_sig *tfm, > .src = src, > .slen = slen, > .dlen = dlen, > + .enc = enc, > }; > int err; > > diff --git a/crypto/testmgr.c b/crypto/testmgr.c > index 216878c8bc3d..d5dd715673dd 100644 > --- a/crypto/testmgr.c > +++ b/crypto/testmgr.c > @@ -4154,11 +4154,12 @@ static int test_akcipher_one(struct crypto_akcipher *tfm, > goto free_all; > memcpy(xbuf[1], c, c_size); > sg_set_buf(&src_tab[2], xbuf[1], c_size); > - akcipher_request_set_crypt(req, src_tab, NULL, m_size, c_size); > + akcipher_request_set_crypt(req, src_tab, NULL, m_size, c_size, > + vecs->enc); > } else { > sg_init_one(&dst, outbuf_enc, out_len_max); > akcipher_request_set_crypt(req, src_tab, &dst, m_size, > - out_len_max); > + out_len_max, NULL); > } > akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, > crypto_req_done, &wait); > @@ -4217,7 +4218,8 @@ static int test_akcipher_one(struct crypto_akcipher *tfm, > sg_init_one(&src, xbuf[0], c_size); > sg_init_one(&dst, outbuf_dec, out_len_max); > crypto_init_wait(&wait); > - akcipher_request_set_crypt(req, &src, &dst, c_size, out_len_max); > + akcipher_request_set_crypt(req, &src, &dst, c_size, out_len_max, > + vecs->enc); > > err = crypto_wait_req(vecs->siggen_sigver_test ? > /* Run asymmetric signature generation */ > diff --git a/crypto/testmgr.h b/crypto/testmgr.h > index 5ca7a412508f..ad57e7af2e14 100644 > --- a/crypto/testmgr.h > +++ b/crypto/testmgr.h > @@ -153,6 +153,7 @@ struct akcipher_testvec { > const unsigned char *params; > const unsigned char *m; > const unsigned char *c; > + const char *enc; > unsigned int key_len; > unsigned int param_len; > unsigned int m_size; > diff --git a/include/crypto/akcipher.h b/include/crypto/akcipher.h > index 670508f1dca1..00bbec69af3b 100644 > --- a/include/crypto/akcipher.h > +++ b/include/crypto/akcipher.h > @@ -30,6 +30,8 @@ > * In case of error where the dst sgl size was insufficient, > * it will be updated to the size required for the operation. > * For verify op this is size of digest part in @src. > + * @enc: For verify op it's the encoding of the signature part of @src. > + * For sign op it's the encoding of the signature in @dst. > * @__ctx: Start of private context data > */ > struct akcipher_request { > @@ -38,6 +40,7 @@ struct akcipher_request { > struct scatterlist *dst; > unsigned int src_len; > unsigned int dst_len; > + const char *enc; > void *__ctx[] CRYPTO_MINALIGN_ATTR; > }; > > @@ -272,17 +275,22 @@ static inline void akcipher_request_set_callback(struct akcipher_request *req, > * @src_len: size of the src input scatter list to be processed > * @dst_len: size of the dst output scatter list or size of signature > * portion in @src for verify op > + * @enc: encoding of signature portion in @src for verify op, > + * encoding of signature in @dst for sign op, > + * NULL for encrypt and decrypt op > */ > static inline void akcipher_request_set_crypt(struct akcipher_request *req, > struct scatterlist *src, > struct scatterlist *dst, > unsigned int src_len, > - unsigned int dst_len) > + unsigned int dst_len, > + const char *enc) > { > req->src = src; > req->dst = dst; > req->src_len = src_len; > req->dst_len = dst_len; > + req->enc = enc; > } > > /** > diff --git a/include/crypto/sig.h b/include/crypto/sig.h > index 641b4714c448..1df18005c854 100644 > --- a/include/crypto/sig.h > +++ b/include/crypto/sig.h > @@ -81,12 +81,13 @@ int crypto_sig_maxsize(struct crypto_sig *tfm); > * @slen: source length > * @dst: destinatino obuffer > * @dlen: destination length > + * @enc: signature encoding > * > * Return: zero on success; error code in case of error > */ > int crypto_sig_sign(struct crypto_sig *tfm, > const void *src, unsigned int slen, > - void *dst, unsigned int dlen); > + void *dst, unsigned int dlen, const char *enc); > > /** > * crypto_sig_verify() - Invoke signature verification > @@ -99,12 +100,13 @@ int crypto_sig_sign(struct crypto_sig *tfm, > * @slen: source length > * @digest: digest > * @dlen: digest length > + * @enc: signature encoding > * > * Return: zero on verification success; error code in case of error. > */ > int crypto_sig_verify(struct crypto_sig *tfm, > const void *src, unsigned int slen, > - const void *digest, unsigned int dlen); > + const void *digest, unsigned int dlen, const char *enc); > > /** > * crypto_sig_set_pubkey() - Invoke set public key operation
Lukas Wunner wrote: > Currently only a single default signature encoding is supported per > akcipher. > > A subsequent commit will allow a second encoding for ecdsa, namely P1363 > alternatively to X9.62. > > To accommodate for that, amend struct akcipher_request and struct > crypto_akcipher_sync_data to store the desired signature encoding for > verify and sign ops. > > Amend akcipher_request_set_crypt(), crypto_sig_verify() and > crypto_sig_sign() with an additional parameter which specifies the > desired signature encoding. Adjust all callers. > > Signed-off-by: Lukas Wunner <lukas@wunner.de> > --- > crypto/akcipher.c | 2 +- > crypto/asymmetric_keys/public_key.c | 4 ++-- > crypto/internal.h | 1 + > crypto/rsa-pkcs1pad.c | 11 +++++++---- > crypto/sig.c | 6 ++++-- > crypto/testmgr.c | 8 +++++--- > crypto/testmgr.h | 1 + > include/crypto/akcipher.h | 10 +++++++++- > include/crypto/sig.h | 6 ++++-- > 9 files changed, 34 insertions(+), 15 deletions(-) I can only review this in generic terms, I just wonder why this decided to pass a string rather than an enum?
On Fri, Oct 06, 2023 at 12:23:59PM -0700, Dan Williams wrote: > Lukas Wunner wrote: > > Currently only a single default signature encoding is supported per > > akcipher. > > > > A subsequent commit will allow a second encoding for ecdsa, namely P1363 > > alternatively to X9.62. > > > > To accommodate for that, amend struct akcipher_request and struct > > crypto_akcipher_sync_data to store the desired signature encoding for > > verify and sign ops. > > > > Amend akcipher_request_set_crypt(), crypto_sig_verify() and > > crypto_sig_sign() with an additional parameter which specifies the > > desired signature encoding. Adjust all callers. > > I can only review this in generic terms, I just wonder why this decided to > pass a string rather than an enum? The keyctl user space interface passes strings and crypto/algapi.c likewise uses strings to identify algorithms. It appears to be the commonly used style in the crypto and keys subsystems. In particular, security/keys/keyctl_pkey.c already uses strings for the signature encoding. I just tried to blend in with the existing code. Happy to make adjustments if Herbert or David say so. Thanks, Lukas
diff --git a/crypto/akcipher.c b/crypto/akcipher.c index 52813f0b19e4..88501c0886d2 100644 --- a/crypto/akcipher.c +++ b/crypto/akcipher.c @@ -221,7 +221,7 @@ int crypto_akcipher_sync_prep(struct crypto_akcipher_sync_data *data) sg = &data->sg; sg_init_one(sg, buf, mlen); akcipher_request_set_crypt(req, sg, data->dst ? sg : NULL, - data->slen, data->dlen); + data->slen, data->dlen, data->enc); crypto_init_wait(&data->cwait); akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP, diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c index abeecb8329b3..7f96e8e501db 100644 --- a/crypto/asymmetric_keys/public_key.c +++ b/crypto/asymmetric_keys/public_key.c @@ -354,7 +354,7 @@ static int software_key_eds_op(struct kernel_pkey_params *params, if (!issig) break; ret = crypto_sig_sign(sig, in, params->in_len, - out, params->out_len); + out, params->out_len, params->encoding); break; default: BUG(); @@ -438,7 +438,7 @@ int public_key_verify_signature(const struct public_key *pkey, goto error_free_key; ret = crypto_sig_verify(tfm, sig->s, sig->s_size, - sig->digest, sig->digest_size); + sig->digest, sig->digest_size, sig->encoding); error_free_key: kfree_sensitive(key); diff --git a/crypto/internal.h b/crypto/internal.h index 63e59240d5fb..268315b13ccd 100644 --- a/crypto/internal.h +++ b/crypto/internal.h @@ -41,6 +41,7 @@ struct crypto_akcipher_sync_data { void *dst; unsigned int slen; unsigned int dlen; + const char *enc; struct akcipher_request *req; struct crypto_wait cwait; diff --git a/crypto/rsa-pkcs1pad.c b/crypto/rsa-pkcs1pad.c index d2e5e104f8cf..5f9313a3b01e 100644 --- a/crypto/rsa-pkcs1pad.c +++ b/crypto/rsa-pkcs1pad.c @@ -262,7 +262,8 @@ static int pkcs1pad_encrypt(struct akcipher_request *req) /* Reuse output buffer */ akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg, - req->dst, ctx->key_size - 1, req->dst_len); + req->dst, ctx->key_size - 1, req->dst_len, + NULL); err = crypto_akcipher_encrypt(&req_ctx->child_req); if (err != -EINPROGRESS && err != -EBUSY) @@ -362,7 +363,7 @@ static int pkcs1pad_decrypt(struct akcipher_request *req) /* Reuse input buffer, output to a new buffer */ akcipher_request_set_crypt(&req_ctx->child_req, req->src, req_ctx->out_sg, req->src_len, - ctx->key_size); + ctx->key_size, NULL); err = crypto_akcipher_decrypt(&req_ctx->child_req); if (err != -EINPROGRESS && err != -EBUSY) @@ -419,7 +420,8 @@ static int pkcs1pad_sign(struct akcipher_request *req) /* Reuse output buffer */ akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg, - req->dst, ctx->key_size - 1, req->dst_len); + req->dst, ctx->key_size - 1, req->dst_len, + req->enc); err = crypto_akcipher_decrypt(&req_ctx->child_req); if (err != -EINPROGRESS && err != -EBUSY) @@ -551,7 +553,8 @@ static int pkcs1pad_verify(struct akcipher_request *req) /* Reuse input buffer, output to a new buffer */ akcipher_request_set_crypt(&req_ctx->child_req, req->src, - req_ctx->out_sg, sig_size, ctx->key_size); + req_ctx->out_sg, sig_size, ctx->key_size, + req->enc); err = crypto_akcipher_encrypt(&req_ctx->child_req); if (err != -EINPROGRESS && err != -EBUSY) diff --git a/crypto/sig.c b/crypto/sig.c index 224c47019297..4fc1a8f865e4 100644 --- a/crypto/sig.c +++ b/crypto/sig.c @@ -89,7 +89,7 @@ EXPORT_SYMBOL_GPL(crypto_sig_maxsize); int crypto_sig_sign(struct crypto_sig *tfm, const void *src, unsigned int slen, - void *dst, unsigned int dlen) + void *dst, unsigned int dlen, const char *enc) { struct crypto_akcipher **ctx = crypto_sig_ctx(tfm); struct crypto_akcipher_sync_data data = { @@ -98,6 +98,7 @@ int crypto_sig_sign(struct crypto_sig *tfm, .dst = dst, .slen = slen, .dlen = dlen, + .enc = enc, }; return crypto_akcipher_sync_prep(&data) ?: @@ -108,7 +109,7 @@ EXPORT_SYMBOL_GPL(crypto_sig_sign); int crypto_sig_verify(struct crypto_sig *tfm, const void *src, unsigned int slen, - const void *digest, unsigned int dlen) + const void *digest, unsigned int dlen, const char *enc) { struct crypto_akcipher **ctx = crypto_sig_ctx(tfm); struct crypto_akcipher_sync_data data = { @@ -116,6 +117,7 @@ int crypto_sig_verify(struct crypto_sig *tfm, .src = src, .slen = slen, .dlen = dlen, + .enc = enc, }; int err; diff --git a/crypto/testmgr.c b/crypto/testmgr.c index 216878c8bc3d..d5dd715673dd 100644 --- a/crypto/testmgr.c +++ b/crypto/testmgr.c @@ -4154,11 +4154,12 @@ static int test_akcipher_one(struct crypto_akcipher *tfm, goto free_all; memcpy(xbuf[1], c, c_size); sg_set_buf(&src_tab[2], xbuf[1], c_size); - akcipher_request_set_crypt(req, src_tab, NULL, m_size, c_size); + akcipher_request_set_crypt(req, src_tab, NULL, m_size, c_size, + vecs->enc); } else { sg_init_one(&dst, outbuf_enc, out_len_max); akcipher_request_set_crypt(req, src_tab, &dst, m_size, - out_len_max); + out_len_max, NULL); } akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, crypto_req_done, &wait); @@ -4217,7 +4218,8 @@ static int test_akcipher_one(struct crypto_akcipher *tfm, sg_init_one(&src, xbuf[0], c_size); sg_init_one(&dst, outbuf_dec, out_len_max); crypto_init_wait(&wait); - akcipher_request_set_crypt(req, &src, &dst, c_size, out_len_max); + akcipher_request_set_crypt(req, &src, &dst, c_size, out_len_max, + vecs->enc); err = crypto_wait_req(vecs->siggen_sigver_test ? /* Run asymmetric signature generation */ diff --git a/crypto/testmgr.h b/crypto/testmgr.h index 5ca7a412508f..ad57e7af2e14 100644 --- a/crypto/testmgr.h +++ b/crypto/testmgr.h @@ -153,6 +153,7 @@ struct akcipher_testvec { const unsigned char *params; const unsigned char *m; const unsigned char *c; + const char *enc; unsigned int key_len; unsigned int param_len; unsigned int m_size; diff --git a/include/crypto/akcipher.h b/include/crypto/akcipher.h index 670508f1dca1..00bbec69af3b 100644 --- a/include/crypto/akcipher.h +++ b/include/crypto/akcipher.h @@ -30,6 +30,8 @@ * In case of error where the dst sgl size was insufficient, * it will be updated to the size required for the operation. * For verify op this is size of digest part in @src. + * @enc: For verify op it's the encoding of the signature part of @src. + * For sign op it's the encoding of the signature in @dst. * @__ctx: Start of private context data */ struct akcipher_request { @@ -38,6 +40,7 @@ struct akcipher_request { struct scatterlist *dst; unsigned int src_len; unsigned int dst_len; + const char *enc; void *__ctx[] CRYPTO_MINALIGN_ATTR; }; @@ -272,17 +275,22 @@ static inline void akcipher_request_set_callback(struct akcipher_request *req, * @src_len: size of the src input scatter list to be processed * @dst_len: size of the dst output scatter list or size of signature * portion in @src for verify op + * @enc: encoding of signature portion in @src for verify op, + * encoding of signature in @dst for sign op, + * NULL for encrypt and decrypt op */ static inline void akcipher_request_set_crypt(struct akcipher_request *req, struct scatterlist *src, struct scatterlist *dst, unsigned int src_len, - unsigned int dst_len) + unsigned int dst_len, + const char *enc) { req->src = src; req->dst = dst; req->src_len = src_len; req->dst_len = dst_len; + req->enc = enc; } /** diff --git a/include/crypto/sig.h b/include/crypto/sig.h index 641b4714c448..1df18005c854 100644 --- a/include/crypto/sig.h +++ b/include/crypto/sig.h @@ -81,12 +81,13 @@ int crypto_sig_maxsize(struct crypto_sig *tfm); * @slen: source length * @dst: destinatino obuffer * @dlen: destination length + * @enc: signature encoding * * Return: zero on success; error code in case of error */ int crypto_sig_sign(struct crypto_sig *tfm, const void *src, unsigned int slen, - void *dst, unsigned int dlen); + void *dst, unsigned int dlen, const char *enc); /** * crypto_sig_verify() - Invoke signature verification @@ -99,12 +100,13 @@ int crypto_sig_sign(struct crypto_sig *tfm, * @slen: source length * @digest: digest * @dlen: digest length + * @enc: signature encoding * * Return: zero on verification success; error code in case of error. */ int crypto_sig_verify(struct crypto_sig *tfm, const void *src, unsigned int slen, - const void *digest, unsigned int dlen); + const void *digest, unsigned int dlen, const char *enc); /** * crypto_sig_set_pubkey() - Invoke set public key operation
Currently only a single default signature encoding is supported per akcipher. A subsequent commit will allow a second encoding for ecdsa, namely P1363 alternatively to X9.62. To accommodate for that, amend struct akcipher_request and struct crypto_akcipher_sync_data to store the desired signature encoding for verify and sign ops. Amend akcipher_request_set_crypt(), crypto_sig_verify() and crypto_sig_sign() with an additional parameter which specifies the desired signature encoding. Adjust all callers. Signed-off-by: Lukas Wunner <lukas@wunner.de> --- crypto/akcipher.c | 2 +- crypto/asymmetric_keys/public_key.c | 4 ++-- crypto/internal.h | 1 + crypto/rsa-pkcs1pad.c | 11 +++++++---- crypto/sig.c | 6 ++++-- crypto/testmgr.c | 8 +++++--- crypto/testmgr.h | 1 + include/crypto/akcipher.h | 10 +++++++++- include/crypto/sig.h | 6 ++++-- 9 files changed, 34 insertions(+), 15 deletions(-)