From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- lib/digsig.c | 244 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 244 insertions(+) create mode 100644 lib/digsig.c (limited to 'lib/digsig.c') diff --git a/lib/digsig.c b/lib/digsig.c new file mode 100644 index 000000000..9dd319c12 --- /dev/null +++ b/lib/digsig.c @@ -0,0 +1,244 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2011 Nokia Corporation + * Copyright (C) 2011 Intel Corporation + * + * Author: + * Dmitry Kasatkin + * + * + * File: sign.c + * implements signature (RSA) verification + * pkcs decoding is based on LibTomCrypt code + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include +#include +#include +#include +#include +#include + +static const char *pkcs_1_v1_5_decode_emsa(const unsigned char *msg, + unsigned long msglen, + unsigned long modulus_bitlen, + unsigned long *outlen) +{ + unsigned long modulus_len, ps_len, i; + + modulus_len = (modulus_bitlen >> 3) + (modulus_bitlen & 7 ? 1 : 0); + + /* test message size */ + if ((msglen > modulus_len) || (modulus_len < 11)) + return NULL; + + /* separate encoded message */ + if (msg[0] != 0x00 || msg[1] != 0x01) + return NULL; + + for (i = 2; i < modulus_len - 1; i++) + if (msg[i] != 0xFF) + break; + + /* separator check */ + if (msg[i] != 0) + /* There was no octet with hexadecimal value 0x00 + to separate ps from m. */ + return NULL; + + ps_len = i - 2; + + *outlen = (msglen - (2 + ps_len + 1)); + + return msg + 2 + ps_len + 1; +} + +/* + * RSA Signature verification with public key + */ +static int digsig_verify_rsa(struct key *key, + const char *sig, int siglen, + const char *h, int hlen) +{ + int err = -EINVAL; + unsigned long len; + unsigned long mlen, mblen; + unsigned nret, l; + int head, i; + unsigned char *out1 = NULL; + const char *m; + MPI in = NULL, res = NULL, pkey[2]; + uint8_t *p, *datap; + const uint8_t *endp; + const struct user_key_payload *ukp; + struct pubkey_hdr *pkh; + + down_read(&key->sem); + ukp = user_key_payload_locked(key); + + if (!ukp) { + /* key was revoked before we acquired its semaphore */ + err = -EKEYREVOKED; + goto err1; + } + + if (ukp->datalen < sizeof(*pkh)) + goto err1; + + pkh = (struct pubkey_hdr *)ukp->data; + + if (pkh->version != 1) + goto err1; + + if (pkh->algo != PUBKEY_ALGO_RSA) + goto err1; + + if (pkh->nmpi != 2) + goto err1; + + datap = pkh->mpi; + endp = ukp->data + ukp->datalen; + + for (i = 0; i < pkh->nmpi; i++) { + unsigned int remaining = endp - datap; + pkey[i] = mpi_read_from_buffer(datap, &remaining); + if (IS_ERR(pkey[i])) { + err = PTR_ERR(pkey[i]); + goto err; + } + datap += remaining; + } + + mblen = mpi_get_nbits(pkey[0]); + mlen = DIV_ROUND_UP(mblen, 8); + + if (mlen == 0) { + err = -EINVAL; + goto err; + } + + err = -ENOMEM; + + out1 = kzalloc(mlen, GFP_KERNEL); + if (!out1) + goto err; + + nret = siglen; + in = mpi_read_from_buffer(sig, &nret); + if (IS_ERR(in)) { + err = PTR_ERR(in); + goto err; + } + + res = mpi_alloc(mpi_get_nlimbs(in) * 2); + if (!res) + goto err; + + err = mpi_powm(res, in, pkey[1], pkey[0]); + if (err) + goto err; + + if (mpi_get_nlimbs(res) * BYTES_PER_MPI_LIMB > mlen) { + err = -EINVAL; + goto err; + } + + p = mpi_get_buffer(res, &l, NULL); + if (!p) { + err = -EINVAL; + goto err; + } + + len = mlen; + head = len - l; + memcpy(out1 + head, p, l); + + kfree(p); + + m = pkcs_1_v1_5_decode_emsa(out1, len, mblen, &len); + + if (!m || len != hlen || memcmp(m, h, hlen)) + err = -EINVAL; + +err: + mpi_free(in); + mpi_free(res); + kfree(out1); + while (--i >= 0) + mpi_free(pkey[i]); +err1: + up_read(&key->sem); + + return err; +} + +/** + * digsig_verify() - digital signature verification with public key + * @keyring: keyring to search key in + * @sig: digital signature + * @siglen: length of the signature + * @data: data + * @datalen: length of the data + * + * Returns 0 on success, -EINVAL otherwise + * + * Verifies data integrity against digital signature. + * Currently only RSA is supported. + * Normally hash of the content is used as a data for this function. + * + */ +int digsig_verify(struct key *keyring, const char *sig, int siglen, + const char *data, int datalen) +{ + struct signature_hdr *sh = (struct signature_hdr *)sig; + struct sha1_ctx ctx; + unsigned char hash[SHA1_DIGEST_SIZE]; + struct key *key; + char name[20]; + int err; + + if (siglen < sizeof(*sh) + 2) + return -EINVAL; + + if (sh->algo != PUBKEY_ALGO_RSA) + return -ENOTSUPP; + + sprintf(name, "%llX", __be64_to_cpup((uint64_t *)sh->keyid)); + + if (keyring) { + /* search in specific keyring */ + key_ref_t kref; + kref = keyring_search(make_key_ref(keyring, 1UL), + &key_type_user, name, true); + if (IS_ERR(kref)) + key = ERR_CAST(kref); + else + key = key_ref_to_ptr(kref); + } else { + key = request_key(&key_type_user, name, NULL); + } + if (IS_ERR(key)) { + pr_err("key not found, id: %s\n", name); + return PTR_ERR(key); + } + + sha1_init(&ctx); + sha1_update(&ctx, data, datalen); + sha1_update(&ctx, sig, sizeof(*sh)); + sha1_final(&ctx, hash); + + /* pass signature mpis address */ + err = digsig_verify_rsa(key, sig + sizeof(*sh), siglen - sizeof(*sh), + hash, sizeof(hash)); + + key_put(key); + + return err ? -EINVAL : 0; +} +EXPORT_SYMBOL_GPL(digsig_verify); + +MODULE_LICENSE("GPL"); -- cgit v1.3.1