| Message ID | d464e1f45d21a29cbbe828dea412206cdc94866b.1637862358.git.msuchanek@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KEXEC_SIG with appended signature | expand |
Hi Michal, On Thu, 25 Nov 2021 19:02:44 +0100 Michal Suchanek <msuchanek@suse.de> wrote: > Multiple users of mod_check_sig check for the marker, then call > mod_check_sig, extract signature length, and remove the signature. > > Put this code in one place together with mod_check_sig. > > Signed-off-by: Michal Suchanek <msuchanek@suse.de> > --- > include/linux/module_signature.h | 1 + > kernel/module_signature.c | 56 ++++++++++++++++++++++++++++- > kernel/module_signing.c | 26 +++----------- > security/integrity/ima/ima_modsig.c | 22 ++---------- > 4 files changed, 63 insertions(+), 42 deletions(-) > > diff --git a/include/linux/module_signature.h b/include/linux/module_signature.h > index 7eb4b00381ac..1343879b72b3 100644 > --- a/include/linux/module_signature.h > +++ b/include/linux/module_signature.h > @@ -42,5 +42,6 @@ struct module_signature { > > int mod_check_sig(const struct module_signature *ms, size_t file_len, > const char *name); > +int mod_parse_sig(const void *data, size_t *len, size_t *sig_len, const char *name); > > #endif /* _LINUX_MODULE_SIGNATURE_H */ > diff --git a/kernel/module_signature.c b/kernel/module_signature.c > index 00132d12487c..784b40575ee4 100644 > --- a/kernel/module_signature.c > +++ b/kernel/module_signature.c > @@ -8,14 +8,36 @@ > > #include <linux/errno.h> > #include <linux/printk.h> > +#include <linux/string.h> > #include <linux/module_signature.h> > #include <asm/byteorder.h> > > +/** > + * mod_check_sig_marker - check that the given data has signature marker at the end > + * > + * @data: Data with appended signature > + * @len: Length of data. Signature marker length is subtracted on success. > + */ > +static inline int mod_check_sig_marker(const void *data, size_t *len) I personally don't like it when a function has a "check" in it's name as it doesn't describe what the function is checking for. For me mod_has_sig_marker is much more precise. I would use that instead. Thanks Philipp > +{ > + const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; > + > + if (markerlen > *len) > + return -ENODATA; > + > + if (memcmp(data + *len - markerlen, MODULE_SIG_STRING, > + markerlen)) > + return -ENODATA; > + > + *len -= markerlen; > + return 0; > +} > + > /** > * mod_check_sig - check that the given signature is sane > * > * @ms: Signature to check. > - * @file_len: Size of the file to which @ms is appended. > + * @file_len: Size of the file to which @ms is appended (without the marker). > * @name: What is being checked. Used for error messages. > */ > int mod_check_sig(const struct module_signature *ms, size_t file_len, > @@ -44,3 +66,35 @@ int mod_check_sig(const struct module_signature *ms, size_t file_len, > > return 0; > } > + > +/** > + * mod_parse_sig - check that the given signature is sane and determine signature length > + * > + * @data: Data with appended signature. > + * @len: Length of data. Signature and marker length is subtracted on success. > + * @sig_len: Length of signature. Filled on success. > + * @name: What is being checked. Used for error messages. > + */ > +int mod_parse_sig(const void *data, size_t *len, size_t *sig_len, const char *name) > +{ > + const struct module_signature *sig; > + int rc; > + > + rc = mod_check_sig_marker(data, len); > + if (rc) > + return rc; > + > + if (*len < sizeof(*sig)) > + return -ENODATA; > + > + sig = (const struct module_signature *)(data + (*len - sizeof(*sig))); > + > + rc = mod_check_sig(sig, *len, name); > + if (rc) > + return rc; > + > + *sig_len = be32_to_cpu(sig->sig_len); > + *len -= *sig_len + sizeof(*sig); > + > + return 0; > +} > diff --git a/kernel/module_signing.c b/kernel/module_signing.c > index cef72a6f6b5d..02bbca90f467 100644 > --- a/kernel/module_signing.c > +++ b/kernel/module_signing.c > @@ -25,35 +25,17 @@ int verify_appended_signature(const void *data, size_t *len, > struct key *trusted_keys, > enum key_being_used_for purpose) > { > - const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; > struct module_signature ms; > - size_t sig_len, modlen = *len; > + size_t sig_len; > int ret; > > - pr_devel("==>%s %s(,%zu)\n", __func__, key_being_used_for[purpose], modlen); > + pr_devel("==>%s %s(,%zu)\n", __func__, key_being_used_for[purpose], *len); > > - if (markerlen > modlen) > - return -ENODATA; > - > - if (memcmp(data + modlen - markerlen, MODULE_SIG_STRING, > - markerlen)) > - return -ENODATA; > - modlen -= markerlen; > - > - if (modlen <= sizeof(ms)) > - return -EBADMSG; > - > - memcpy(&ms, data + (modlen - sizeof(ms)), sizeof(ms)); > - > - ret = mod_check_sig(&ms, modlen, key_being_used_for[purpose]); > + ret = mod_parse_sig(data, len, &sig_len, key_being_used_for[purpose]); > if (ret) > return ret; > > - sig_len = be32_to_cpu(ms.sig_len); > - modlen -= sig_len + sizeof(ms); > - *len = modlen; > - > - return verify_pkcs7_signature(data, modlen, data + modlen, sig_len, > + return verify_pkcs7_signature(data, *len, data + *len, sig_len, > trusted_keys, > purpose, > NULL, NULL); > diff --git a/security/integrity/ima/ima_modsig.c b/security/integrity/ima/ima_modsig.c > index fb25723c65bc..46917eb37fd8 100644 > --- a/security/integrity/ima/ima_modsig.c > +++ b/security/integrity/ima/ima_modsig.c > @@ -37,33 +37,17 @@ struct modsig { > * > * Return: 0 on success, error code otherwise. > */ > -int ima_read_modsig(enum ima_hooks func, const void *buf, loff_t buf_len, > +int ima_read_modsig(enum ima_hooks func, const void *buf, loff_t len, > struct modsig **modsig) > { > - const size_t marker_len = strlen(MODULE_SIG_STRING); > - const struct module_signature *sig; > struct modsig *hdr; > - size_t sig_len; > - const void *p; > + size_t sig_len, buf_len = len; > int rc; > > - if (buf_len <= marker_len + sizeof(*sig)) > - return -ENOENT; > - > - p = buf + buf_len - marker_len; > - if (memcmp(p, MODULE_SIG_STRING, marker_len)) > - return -ENOENT; > - > - buf_len -= marker_len; > - sig = (const struct module_signature *)(p - sizeof(*sig)); > - > - rc = mod_check_sig(sig, buf_len, func_tokens[func]); > + rc = mod_parse_sig(buf, &buf_len, &sig_len, func_tokens[func]); > if (rc) > return rc; > > - sig_len = be32_to_cpu(sig->sig_len); > - buf_len -= sig_len + sizeof(*sig); > - > /* Allocate sig_len additional bytes to hold the raw PKCS#7 data. */ > hdr = kzalloc(sizeof(*hdr) + sig_len, GFP_KERNEL); > if (!hdr)
Hello, On Tue, Dec 07, 2021 at 05:10:34PM +0100, Philipp Rudo wrote: > Hi Michal, > > On Thu, 25 Nov 2021 19:02:44 +0100 > Michal Suchanek <msuchanek@suse.de> wrote: > > > Multiple users of mod_check_sig check for the marker, then call > > mod_check_sig, extract signature length, and remove the signature. > > > > Put this code in one place together with mod_check_sig. > > > > Signed-off-by: Michal Suchanek <msuchanek@suse.de> > > --- > > include/linux/module_signature.h | 1 + > > kernel/module_signature.c | 56 ++++++++++++++++++++++++++++- > > kernel/module_signing.c | 26 +++----------- > > security/integrity/ima/ima_modsig.c | 22 ++---------- > > 4 files changed, 63 insertions(+), 42 deletions(-) > > > > diff --git a/include/linux/module_signature.h b/include/linux/module_signature.h > > index 7eb4b00381ac..1343879b72b3 100644 > > --- a/include/linux/module_signature.h > > +++ b/include/linux/module_signature.h > > @@ -42,5 +42,6 @@ struct module_signature { > > > > int mod_check_sig(const struct module_signature *ms, size_t file_len, > > const char *name); > > +int mod_parse_sig(const void *data, size_t *len, size_t *sig_len, const char *name); > > > > #endif /* _LINUX_MODULE_SIGNATURE_H */ > > diff --git a/kernel/module_signature.c b/kernel/module_signature.c > > index 00132d12487c..784b40575ee4 100644 > > --- a/kernel/module_signature.c > > +++ b/kernel/module_signature.c > > @@ -8,14 +8,36 @@ > > > > #include <linux/errno.h> > > #include <linux/printk.h> > > +#include <linux/string.h> > > #include <linux/module_signature.h> > > #include <asm/byteorder.h> > > > > +/** > > + * mod_check_sig_marker - check that the given data has signature marker at the end > > + * > > + * @data: Data with appended signature > > + * @len: Length of data. Signature marker length is subtracted on success. > > + */ > > +static inline int mod_check_sig_marker(const void *data, size_t *len) > > I personally don't like it when a function has a "check" in it's name > as it doesn't describe what the function is checking for. For me It is consistent with mod_check_sig > mod_has_sig_marker is much more precise. I would use that instead. It actually would not because it does more than that. Thanks Michal > > Thanks > Philipp > > > +{ > > + const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; > > + > > + if (markerlen > *len) > > + return -ENODATA; > > + > > + if (memcmp(data + *len - markerlen, MODULE_SIG_STRING, > > + markerlen)) > > + return -ENODATA; > > + > > + *len -= markerlen; > > + return 0; > > +} > > + > > /** > > * mod_check_sig - check that the given signature is sane > > * > > * @ms: Signature to check. > > - * @file_len: Size of the file to which @ms is appended. > > + * @file_len: Size of the file to which @ms is appended (without the marker). > > * @name: What is being checked. Used for error messages. > > */ > > int mod_check_sig(const struct module_signature *ms, size_t file_len, > > @@ -44,3 +66,35 @@ int mod_check_sig(const struct module_signature *ms, size_t file_len, > > > > return 0; > > } > > + > > +/** > > + * mod_parse_sig - check that the given signature is sane and determine signature length > > + * > > + * @data: Data with appended signature. > > + * @len: Length of data. Signature and marker length is subtracted on success. > > + * @sig_len: Length of signature. Filled on success. > > + * @name: What is being checked. Used for error messages. > > + */ > > +int mod_parse_sig(const void *data, size_t *len, size_t *sig_len, const char *name) > > +{ > > + const struct module_signature *sig; > > + int rc; > > + > > + rc = mod_check_sig_marker(data, len); > > + if (rc) > > + return rc; > > + > > + if (*len < sizeof(*sig)) > > + return -ENODATA; > > + > > + sig = (const struct module_signature *)(data + (*len - sizeof(*sig))); > > + > > + rc = mod_check_sig(sig, *len, name); > > + if (rc) > > + return rc; > > + > > + *sig_len = be32_to_cpu(sig->sig_len); > > + *len -= *sig_len + sizeof(*sig); > > + > > + return 0; > > +} > > diff --git a/kernel/module_signing.c b/kernel/module_signing.c > > index cef72a6f6b5d..02bbca90f467 100644 > > --- a/kernel/module_signing.c > > +++ b/kernel/module_signing.c > > @@ -25,35 +25,17 @@ int verify_appended_signature(const void *data, size_t *len, > > struct key *trusted_keys, > > enum key_being_used_for purpose) > > { > > - const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; > > struct module_signature ms; > > - size_t sig_len, modlen = *len; > > + size_t sig_len; > > int ret; > > > > - pr_devel("==>%s %s(,%zu)\n", __func__, key_being_used_for[purpose], modlen); > > + pr_devel("==>%s %s(,%zu)\n", __func__, key_being_used_for[purpose], *len); > > > > - if (markerlen > modlen) > > - return -ENODATA; > > - > > - if (memcmp(data + modlen - markerlen, MODULE_SIG_STRING, > > - markerlen)) > > - return -ENODATA; > > - modlen -= markerlen; > > - > > - if (modlen <= sizeof(ms)) > > - return -EBADMSG; > > - > > - memcpy(&ms, data + (modlen - sizeof(ms)), sizeof(ms)); > > - > > - ret = mod_check_sig(&ms, modlen, key_being_used_for[purpose]); > > + ret = mod_parse_sig(data, len, &sig_len, key_being_used_for[purpose]); > > if (ret) > > return ret; > > > > - sig_len = be32_to_cpu(ms.sig_len); > > - modlen -= sig_len + sizeof(ms); > > - *len = modlen; > > - > > - return verify_pkcs7_signature(data, modlen, data + modlen, sig_len, > > + return verify_pkcs7_signature(data, *len, data + *len, sig_len, > > trusted_keys, > > purpose, > > NULL, NULL); > > diff --git a/security/integrity/ima/ima_modsig.c b/security/integrity/ima/ima_modsig.c > > index fb25723c65bc..46917eb37fd8 100644 > > --- a/security/integrity/ima/ima_modsig.c > > +++ b/security/integrity/ima/ima_modsig.c > > @@ -37,33 +37,17 @@ struct modsig { > > * > > * Return: 0 on success, error code otherwise. > > */ > > -int ima_read_modsig(enum ima_hooks func, const void *buf, loff_t buf_len, > > +int ima_read_modsig(enum ima_hooks func, const void *buf, loff_t len, > > struct modsig **modsig) > > { > > - const size_t marker_len = strlen(MODULE_SIG_STRING); > > - const struct module_signature *sig; > > struct modsig *hdr; > > - size_t sig_len; > > - const void *p; > > + size_t sig_len, buf_len = len; > > int rc; > > > > - if (buf_len <= marker_len + sizeof(*sig)) > > - return -ENOENT; > > - > > - p = buf + buf_len - marker_len; > > - if (memcmp(p, MODULE_SIG_STRING, marker_len)) > > - return -ENOENT; > > - > > - buf_len -= marker_len; > > - sig = (const struct module_signature *)(p - sizeof(*sig)); > > - > > - rc = mod_check_sig(sig, buf_len, func_tokens[func]); > > + rc = mod_parse_sig(buf, &buf_len, &sig_len, func_tokens[func]); > > if (rc) > > return rc; > > > > - sig_len = be32_to_cpu(sig->sig_len); > > - buf_len -= sig_len + sizeof(*sig); > > - > > /* Allocate sig_len additional bytes to hold the raw PKCS#7 data. */ > > hdr = kzalloc(sizeof(*hdr) + sig_len, GFP_KERNEL); > > if (!hdr) >
diff --git a/include/linux/module_signature.h b/include/linux/module_signature.h index 7eb4b00381ac..1343879b72b3 100644 --- a/include/linux/module_signature.h +++ b/include/linux/module_signature.h @@ -42,5 +42,6 @@ struct module_signature { int mod_check_sig(const struct module_signature *ms, size_t file_len, const char *name); +int mod_parse_sig(const void *data, size_t *len, size_t *sig_len, const char *name); #endif /* _LINUX_MODULE_SIGNATURE_H */ diff --git a/kernel/module_signature.c b/kernel/module_signature.c index 00132d12487c..784b40575ee4 100644 --- a/kernel/module_signature.c +++ b/kernel/module_signature.c @@ -8,14 +8,36 @@ #include <linux/errno.h> #include <linux/printk.h> +#include <linux/string.h> #include <linux/module_signature.h> #include <asm/byteorder.h> +/** + * mod_check_sig_marker - check that the given data has signature marker at the end + * + * @data: Data with appended signature + * @len: Length of data. Signature marker length is subtracted on success. + */ +static inline int mod_check_sig_marker(const void *data, size_t *len) +{ + const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; + + if (markerlen > *len) + return -ENODATA; + + if (memcmp(data + *len - markerlen, MODULE_SIG_STRING, + markerlen)) + return -ENODATA; + + *len -= markerlen; + return 0; +} + /** * mod_check_sig - check that the given signature is sane * * @ms: Signature to check. - * @file_len: Size of the file to which @ms is appended. + * @file_len: Size of the file to which @ms is appended (without the marker). * @name: What is being checked. Used for error messages. */ int mod_check_sig(const struct module_signature *ms, size_t file_len, @@ -44,3 +66,35 @@ int mod_check_sig(const struct module_signature *ms, size_t file_len, return 0; } + +/** + * mod_parse_sig - check that the given signature is sane and determine signature length + * + * @data: Data with appended signature. + * @len: Length of data. Signature and marker length is subtracted on success. + * @sig_len: Length of signature. Filled on success. + * @name: What is being checked. Used for error messages. + */ +int mod_parse_sig(const void *data, size_t *len, size_t *sig_len, const char *name) +{ + const struct module_signature *sig; + int rc; + + rc = mod_check_sig_marker(data, len); + if (rc) + return rc; + + if (*len < sizeof(*sig)) + return -ENODATA; + + sig = (const struct module_signature *)(data + (*len - sizeof(*sig))); + + rc = mod_check_sig(sig, *len, name); + if (rc) + return rc; + + *sig_len = be32_to_cpu(sig->sig_len); + *len -= *sig_len + sizeof(*sig); + + return 0; +} diff --git a/kernel/module_signing.c b/kernel/module_signing.c index cef72a6f6b5d..02bbca90f467 100644 --- a/kernel/module_signing.c +++ b/kernel/module_signing.c @@ -25,35 +25,17 @@ int verify_appended_signature(const void *data, size_t *len, struct key *trusted_keys, enum key_being_used_for purpose) { - const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; struct module_signature ms; - size_t sig_len, modlen = *len; + size_t sig_len; int ret; - pr_devel("==>%s %s(,%zu)\n", __func__, key_being_used_for[purpose], modlen); + pr_devel("==>%s %s(,%zu)\n", __func__, key_being_used_for[purpose], *len); - if (markerlen > modlen) - return -ENODATA; - - if (memcmp(data + modlen - markerlen, MODULE_SIG_STRING, - markerlen)) - return -ENODATA; - modlen -= markerlen; - - if (modlen <= sizeof(ms)) - return -EBADMSG; - - memcpy(&ms, data + (modlen - sizeof(ms)), sizeof(ms)); - - ret = mod_check_sig(&ms, modlen, key_being_used_for[purpose]); + ret = mod_parse_sig(data, len, &sig_len, key_being_used_for[purpose]); if (ret) return ret; - sig_len = be32_to_cpu(ms.sig_len); - modlen -= sig_len + sizeof(ms); - *len = modlen; - - return verify_pkcs7_signature(data, modlen, data + modlen, sig_len, + return verify_pkcs7_signature(data, *len, data + *len, sig_len, trusted_keys, purpose, NULL, NULL); diff --git a/security/integrity/ima/ima_modsig.c b/security/integrity/ima/ima_modsig.c index fb25723c65bc..46917eb37fd8 100644 --- a/security/integrity/ima/ima_modsig.c +++ b/security/integrity/ima/ima_modsig.c @@ -37,33 +37,17 @@ struct modsig { * * Return: 0 on success, error code otherwise. */ -int ima_read_modsig(enum ima_hooks func, const void *buf, loff_t buf_len, +int ima_read_modsig(enum ima_hooks func, const void *buf, loff_t len, struct modsig **modsig) { - const size_t marker_len = strlen(MODULE_SIG_STRING); - const struct module_signature *sig; struct modsig *hdr; - size_t sig_len; - const void *p; + size_t sig_len, buf_len = len; int rc; - if (buf_len <= marker_len + sizeof(*sig)) - return -ENOENT; - - p = buf + buf_len - marker_len; - if (memcmp(p, MODULE_SIG_STRING, marker_len)) - return -ENOENT; - - buf_len -= marker_len; - sig = (const struct module_signature *)(p - sizeof(*sig)); - - rc = mod_check_sig(sig, buf_len, func_tokens[func]); + rc = mod_parse_sig(buf, &buf_len, &sig_len, func_tokens[func]); if (rc) return rc; - sig_len = be32_to_cpu(sig->sig_len); - buf_len -= sig_len + sizeof(*sig); - /* Allocate sig_len additional bytes to hold the raw PKCS#7 data. */ hdr = kzalloc(sizeof(*hdr) + sig_len, GFP_KERNEL); if (!hdr)
Multiple users of mod_check_sig check for the marker, then call mod_check_sig, extract signature length, and remove the signature. Put this code in one place together with mod_check_sig. Signed-off-by: Michal Suchanek <msuchanek@suse.de> --- include/linux/module_signature.h | 1 + kernel/module_signature.c | 56 ++++++++++++++++++++++++++++- kernel/module_signing.c | 26 +++----------- security/integrity/ima/ima_modsig.c | 22 ++---------- 4 files changed, 63 insertions(+), 42 deletions(-)