From 47f9e4c924025c5be87959d3335e66fcbb7f6b5c Mon Sep 17 00:00:00 2001 From: David Howells Date: Tue, 14 Mar 2023 15:15:18 +0000 Subject: [PATCH 1/3] keys: Do not cache key in task struct if key is requested from kernel thread The key which gets cached in task structure from a kernel thread does not get invalidated even after expiry. Due to which, a new key request from kernel thread will be served with the cached key if it's present in task struct irrespective of the key validity. The change is to not cache key in task_struct when key requested from kernel thread so that kernel thread gets a valid key on every key request. The problem has been seen with the cifs module doing DNS lookups from a kernel thread and the results getting pinned by being attached to that kernel thread's cache - and thus not something that can be easily got rid of. The cache would ordinarily be cleared by notify-resume, but kernel threads don't do that. This isn't seen with AFS because AFS is doing request_key() within the kernel half of a user thread - which will do notify-resume. Fixes: 7743c48e54ee ("keys: Cache result of request_key*() temporarily in task_struct") Signed-off-by: Bharath SM Signed-off-by: David Howells Reviewed-by: Jarkko Sakkinen cc: Shyam Prasad N cc: Steve French cc: keyrings@vger.kernel.org cc: linux-cifs@vger.kernel.org cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/CAGypqWw951d=zYRbdgNR4snUDvJhWL=q3=WOyh7HhSJupjz2vA@mail.gmail.com/ --- security/keys/request_key.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/security/keys/request_key.c b/security/keys/request_key.c index 2da4404276f0..07a0ef2baacd 100644 --- a/security/keys/request_key.c +++ b/security/keys/request_key.c @@ -38,9 +38,12 @@ static void cache_requested_key(struct key *key) #ifdef CONFIG_KEYS_REQUEST_CACHE struct task_struct *t = current; - key_put(t->cached_requested_key); - t->cached_requested_key = key_get(key); - set_tsk_thread_flag(t, TIF_NOTIFY_RESUME); + /* Do not cache key if it is a kernel thread */ + if (!(t->flags & PF_KTHREAD)) { + key_put(t->cached_requested_key); + t->cached_requested_key = key_get(key); + set_tsk_thread_flag(t, TIF_NOTIFY_RESUME); + } #endif } From 4fc5c74dde69a7eda172514aaeb5a7df3600adb3 Mon Sep 17 00:00:00 2001 From: Robbie Harwood Date: Mon, 20 Feb 2023 12:12:53 -0500 Subject: [PATCH 2/3] verify_pefile: relax wrapper length check The PE Format Specification (section "The Attribute Certificate Table (Image Only)") states that `dwLength` is to be rounded up to 8-byte alignment when used for traversal. Therefore, the field is not required to be an 8-byte multiple in the first place. Accordingly, pesign has not performed this alignment since version 0.110. This causes kexec failure on pesign'd binaries with "PEFILE: Signature wrapper len wrong". Update the comment and relax the check. Signed-off-by: Robbie Harwood Signed-off-by: David Howells cc: Jarkko Sakkinen cc: Eric Biederman cc: Herbert Xu cc: keyrings@vger.kernel.org cc: linux-crypto@vger.kernel.org cc: kexec@lists.infradead.org Link: https://learn.microsoft.com/en-us/windows/win32/debug/pe-format#the-attribute-certificate-table-image-only Link: https://github.com/rhboot/pesign Link: https://lore.kernel.org/r/20230220171254.592347-2-rharwood@redhat.com/ # v2 --- crypto/asymmetric_keys/verify_pefile.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/crypto/asymmetric_keys/verify_pefile.c b/crypto/asymmetric_keys/verify_pefile.c index 7553ab18db89..fe1bb374239d 100644 --- a/crypto/asymmetric_keys/verify_pefile.c +++ b/crypto/asymmetric_keys/verify_pefile.c @@ -135,11 +135,15 @@ static int pefile_strip_sig_wrapper(const void *pebuf, pr_debug("sig wrapper = { %x, %x, %x }\n", wrapper.length, wrapper.revision, wrapper.cert_type); - /* Both pesign and sbsign round up the length of certificate table - * (in optional header data directories) to 8 byte alignment. + /* sbsign rounds up the length of certificate table (in optional + * header data directories) to 8 byte alignment. However, the PE + * specification states that while entries are 8-byte aligned, this is + * not included in their length, and as a result, pesign has not + * rounded up since 0.110. */ - if (round_up(wrapper.length, 8) != ctx->sig_len) { - pr_debug("Signature wrapper len wrong\n"); + if (wrapper.length > ctx->sig_len) { + pr_debug("Signature wrapper bigger than sig len (%x > %x)\n", + ctx->sig_len, wrapper.length); return -ELIBBAD; } if (wrapper.revision != WIN_CERT_REVISION_2_0) { From 3584c1dbfffdabf8e3dc1dd25748bb38dd01cd43 Mon Sep 17 00:00:00 2001 From: Robbie Harwood Date: Mon, 20 Feb 2023 12:12:54 -0500 Subject: [PATCH 3/3] asymmetric_keys: log on fatal failures in PE/pkcs7 These particular errors can be encountered while trying to kexec when secureboot lockdown is in place. Without this change, even with a signed debug build, one still needs to reboot the machine to add the appropriate dyndbg parameters (since lockdown blocks debugfs). Accordingly, upgrade all pr_debug() before fatal error into pr_warn(). Signed-off-by: Robbie Harwood Signed-off-by: David Howells cc: Jarkko Sakkinen cc: Eric Biederman cc: Herbert Xu cc: keyrings@vger.kernel.org cc: linux-crypto@vger.kernel.org cc: kexec@lists.infradead.org Link: https://lore.kernel.org/r/20230220171254.592347-3-rharwood@redhat.com/ # v2 --- crypto/asymmetric_keys/pkcs7_verify.c | 10 +++++----- crypto/asymmetric_keys/verify_pefile.c | 24 ++++++++++++------------ 2 files changed, 17 insertions(+), 17 deletions(-) diff --git a/crypto/asymmetric_keys/pkcs7_verify.c b/crypto/asymmetric_keys/pkcs7_verify.c index 4fa769c4bcdb..f0d4ff3c20a8 100644 --- a/crypto/asymmetric_keys/pkcs7_verify.c +++ b/crypto/asymmetric_keys/pkcs7_verify.c @@ -79,16 +79,16 @@ static int pkcs7_digest(struct pkcs7_message *pkcs7, } if (sinfo->msgdigest_len != sig->digest_size) { - pr_debug("Sig %u: Invalid digest size (%u)\n", - sinfo->index, sinfo->msgdigest_len); + pr_warn("Sig %u: Invalid digest size (%u)\n", + sinfo->index, sinfo->msgdigest_len); ret = -EBADMSG; goto error; } if (memcmp(sig->digest, sinfo->msgdigest, sinfo->msgdigest_len) != 0) { - pr_debug("Sig %u: Message digest doesn't match\n", - sinfo->index); + pr_warn("Sig %u: Message digest doesn't match\n", + sinfo->index); ret = -EKEYREJECTED; goto error; } @@ -478,7 +478,7 @@ int pkcs7_supply_detached_data(struct pkcs7_message *pkcs7, const void *data, size_t datalen) { if (pkcs7->data) { - pr_debug("Data already supplied\n"); + pr_warn("Data already supplied\n"); return -EINVAL; } pkcs7->data = data; diff --git a/crypto/asymmetric_keys/verify_pefile.c b/crypto/asymmetric_keys/verify_pefile.c index fe1bb374239d..22beaf2213a2 100644 --- a/crypto/asymmetric_keys/verify_pefile.c +++ b/crypto/asymmetric_keys/verify_pefile.c @@ -74,7 +74,7 @@ static int pefile_parse_binary(const void *pebuf, unsigned int pelen, break; default: - pr_debug("Unknown PEOPT magic = %04hx\n", pe32->magic); + pr_warn("Unknown PEOPT magic = %04hx\n", pe32->magic); return -ELIBBAD; } @@ -95,7 +95,7 @@ static int pefile_parse_binary(const void *pebuf, unsigned int pelen, ctx->certs_size = ddir->certs.size; if (!ddir->certs.virtual_address || !ddir->certs.size) { - pr_debug("Unsigned PE binary\n"); + pr_warn("Unsigned PE binary\n"); return -ENODATA; } @@ -127,7 +127,7 @@ static int pefile_strip_sig_wrapper(const void *pebuf, unsigned len; if (ctx->sig_len < sizeof(wrapper)) { - pr_debug("Signature wrapper too short\n"); + pr_warn("Signature wrapper too short\n"); return -ELIBBAD; } @@ -142,16 +142,16 @@ static int pefile_strip_sig_wrapper(const void *pebuf, * rounded up since 0.110. */ if (wrapper.length > ctx->sig_len) { - pr_debug("Signature wrapper bigger than sig len (%x > %x)\n", - ctx->sig_len, wrapper.length); + pr_warn("Signature wrapper bigger than sig len (%x > %x)\n", + ctx->sig_len, wrapper.length); return -ELIBBAD; } if (wrapper.revision != WIN_CERT_REVISION_2_0) { - pr_debug("Signature is not revision 2.0\n"); + pr_warn("Signature is not revision 2.0\n"); return -ENOTSUPP; } if (wrapper.cert_type != WIN_CERT_TYPE_PKCS_SIGNED_DATA) { - pr_debug("Signature certificate type is not PKCS\n"); + pr_warn("Signature certificate type is not PKCS\n"); return -ENOTSUPP; } @@ -164,7 +164,7 @@ static int pefile_strip_sig_wrapper(const void *pebuf, ctx->sig_offset += sizeof(wrapper); ctx->sig_len -= sizeof(wrapper); if (ctx->sig_len < 4) { - pr_debug("Signature data missing\n"); + pr_warn("Signature data missing\n"); return -EKEYREJECTED; } @@ -198,7 +198,7 @@ check_len: return 0; } not_pkcs7: - pr_debug("Signature data not PKCS#7\n"); + pr_warn("Signature data not PKCS#7\n"); return -ELIBBAD; } @@ -341,8 +341,8 @@ static int pefile_digest_pe(const void *pebuf, unsigned int pelen, digest_size = crypto_shash_digestsize(tfm); if (digest_size != ctx->digest_len) { - pr_debug("Digest size mismatch (%zx != %x)\n", - digest_size, ctx->digest_len); + pr_warn("Digest size mismatch (%zx != %x)\n", + digest_size, ctx->digest_len); ret = -EBADMSG; goto error_no_desc; } @@ -373,7 +373,7 @@ static int pefile_digest_pe(const void *pebuf, unsigned int pelen, * PKCS#7 certificate. */ if (memcmp(digest, ctx->digest, ctx->digest_len) != 0) { - pr_debug("Digest mismatch\n"); + pr_warn("Digest mismatch\n"); ret = -EKEYREJECTED; } else { pr_debug("The digests match!\n");