ima-evm-utils: simplify digest alias handling

- Make digest name search work just with simple strcmp() and three arrays, dropping strmatch().
- Remove get_digestbyname() which was doing two hash name resolving attempts, reverting to use plain EVP_get_digestbyname(). This will force the user to specify the proper hash name depending on what OpenSSL provides, allowing to specify older hash name in older OpenSSL.
- Improve hash_info parser to produce hash_algo_name[] more resembling what is in the kernel, making algocmp() not needed and removed.
- Fix indent in get_hash_algo_by_id().

---
 src/hash_info.gen |  8 ++++-
 src/libimaevm.c   | 94 ++++++++++++-------------------------------------------
 2 files changed, 27 insertions(+), 75 deletions(-)

src/hash_info.gen +7 -1

index 60fc750..54532ca 100755
@@ -39,5 +39,11 @@ printf "\tHASH_ALGO__LAST\n"
 echo "};"
 
 echo "const char *const hash_algo_name[HASH_ALGO__LAST] = {"
-sed -n 's/HASH_ALGO_\(.*\),/[HASH_ALGO_\1] = "\L\1\E",/p' $HASH_INFO
+sed -n 's/HASH_ALGO_\(.*\),/\1 \L\1\E/p' $HASH_INFO | \
+  while read a b; do
+    # Normalize text hash name: if it contains underscore between
+    # digits replace it with a dash, other underscores are removed.
+    b=$(echo "$b" | sed "s/\([0-9]\)_\([0-9]\)/\1-\2/g;s/_//g")
+    printf '\t%-26s = "%s",\n' "[HASH_ALGO_$a]" "$b"
+  done
 echo "};"

src/libimaevm.c +20 -74

index d9ffa13..102d6fc 100644
@@ -63,6 +63,7 @@
 #include "imaevm.h"
 #include "hash_info.h"
 
+/* Named that are primary for OpenSSL. */
 const char *const pkey_hash_algo[PKEY_HASH__LAST] = {
 	[PKEY_HASH_MD4]		= "md4",
 	[PKEY_HASH_MD5]		= "md5",

@@ -72,8 +73,14 @@ const char *const pkey_hash_algo[PKEY_HASH__LAST] = {
 	[PKEY_HASH_SHA384]	= "sha384",
 	[PKEY_HASH_SHA512]	= "sha512",
 	[PKEY_HASH_SHA224]	= "sha224",
-	[PKEY_HASH_STREEBOG_256] = "md_gost12_256,streebog256",
-	[PKEY_HASH_STREEBOG_512] = "md_gost12_512,streebog512",
+	[PKEY_HASH_STREEBOG_256] = "md_gost12_256",
+	[PKEY_HASH_STREEBOG_512] = "md_gost12_512",
+};
+
+/* Names that are primary for the kernel. */
+const char *const pkey_hash_algo_kern[PKEY_HASH__LAST] = {
+	[PKEY_HASH_STREEBOG_256] = "streebog256",
+	[PKEY_HASH_STREEBOG_512] = "streebog512",
 };
 
 /*

@@ -160,9 +167,9 @@ void dump(const void *ptr, int len)
 const char *get_hash_algo_by_id(int algo)
 {
 	if (algo < PKEY_HASH__LAST)
-	    return pkey_hash_algo[algo];
+		return pkey_hash_algo[algo];
 	if (algo < HASH_ALGO__LAST)
-	    return hash_algo_name[algo];
+		return hash_algo_name[algo];
 
 	log_err("digest %d not found\n", algo);
 	return "unknown";

@@ -286,35 +293,6 @@ static int add_dev_hash(struct stat *st, EVP_MD_CTX *ctx)
 	return !EVP_DigestUpdate(ctx, &dev, sizeof(dev));
 }
 
-/* Call EVP_get_digestbyname with provided name and with alias,
- * which is first name in the comma separated list of names
- * in pkey_hash_algo.
- */
-static const EVP_MD *get_digestbyname(const char *name)
-{
-	const EVP_MD *md;
-
-	md = EVP_get_digestbyname(params.hash_algo);
-	if (!md) {
-		char alias[MAX_DIGEST_NAME];
-		int len;
-		int algo_id;
-		const char *algo_alias;
-
-		/* try to get algo by its alias */
-		algo_id = get_hash_algo(params.hash_algo);
-		algo_alias = get_hash_algo_by_id(algo_id);
-		len = strchrnul(algo_alias, ',') - algo_alias;
-		if (len < sizeof(alias)) {
-			memcpy(alias, algo_alias, len);
-			alias[len] = '\0';
-			if (strcmp(params.hash_algo, alias))
-				md = EVP_get_digestbyname(alias);
-		}
-	}
-	return md;
-}
-
 int ima_calc_hash(const char *file, uint8_t *hash)
 {
 	const EVP_MD *md;

@@ -336,7 +314,7 @@ int ima_calc_hash(const char *file, uint8_t *hash)
 		return err;
 	}
 
-	md = get_digestbyname(params.hash_algo);
+	md = EVP_get_digestbyname(params.hash_algo);
 	if (!md) {
 		log_err("EVP_get_digestbyname(%s) failed\n", params.hash_algo);
 		return 1;

@@ -572,42 +550,6 @@ int verify_hash_v2(const char *file, const unsigned char *hash, int size,
 	return 0;
 }
 
-/* compare algo names case insensitively and ignoring separators */
-static int algocmp(const char *a, const char *b)
-{
-	while (*a && *b) {
-		int cha, chb;
-
-		cha = tolower((unsigned char)*a++);
-		if (!isalnum(cha))
-			continue;
-		chb = tolower((unsigned char)*b++);
-		if (!isalnum(chb)) {
-			a--;
-			continue;
-		}
-		if (cha != chb)
-			return -1;
-	}
-	return *a || *b;
-}
-
-static int strmatch(const char *needle, const char *haystack)
-{
-	int len = strlen(needle);
-	const char *p = haystack;
-	const char *t;
-
-	for (t = strchrnul(p, ','); *p; p = t, t = strchrnul(p, ',')) {
-		if (t - p == len &&
-		    !strncmp(needle, p, len))
-			return 0;
-		if (!*t++)
-			break;
-	}
-	return 1;
-}
-
 int get_hash_algo(const char *algo)
 {
 	int i;

@@ -615,15 +557,19 @@ int get_hash_algo(const char *algo)
 	/* first iterate over builtin algorithms */
 	for (i = 0; i < PKEY_HASH__LAST; i++)
 		if (pkey_hash_algo[i] &&
-		    !strmatch(algo, pkey_hash_algo[i]))
+		    !strcmp(algo, pkey_hash_algo[i]))
+			return i;
+
+	for (i = 0; i < PKEY_HASH__LAST; i++)
+		if (pkey_hash_algo_kern[i] &&
+		    !strcmp(algo, pkey_hash_algo_kern[i]))
 			return i;
 
 	/* iterate over algorithms provided by kernel-headers */
-	for (i = 0; i < HASH_ALGO__LAST; i++) {
+	for (i = 0; i < HASH_ALGO__LAST; i++)
 		if (hash_algo_name[i] &&
-		    !algocmp(algo, hash_algo_name[i]))
+		    !strcmp(algo, hash_algo_name[i]))
 			return i;
-	}
 
 	log_info("digest %s not found, fall back to sha1\n", algo);
 	return PKEY_HASH_SHA1;

Hi Vitaly,

Quoted 10 lines · Vitaly Chikunov

- Make digest name search work just with simple strcmp() and three arrays, dropping strmatch().
- Remove get_digestbyname() which was doing two hash name resolving attempts, reverting to use plain EVP_get_digestbyname(). This will force the user to specify the proper hash name depending on what OpenSSL provides, allowing to specify older hash name in older OpenSSL.
- Improve hash_info parser to produce hash_algo_name[] more resembling what is in the kernel, making algocmp() not needed and removed.
- Fix indent in get_hash_algo_by_id().

Thanks, this is a lot better.  As there isn't a "Signed-off-by", did

you want to squash this with the original patch - "Extract digest algorithms from hash_info.h"?

Mimi

Quoted 175 lines

---
 src/hash_info.gen |  8 ++++-
 src/libimaevm.c   | 94 ++++++++++++-------------------------------------------
 2 files changed, 27 insertions(+), 75 deletions(-)

src/hash_info.gen +7 -1

index 60fc750..54532ca 100755
@@ -39,5 +39,11 @@ printf "\tHASH_ALGO__LAST\n"
 echo "};"
 
 echo "const char *const hash_algo_name[HASH_ALGO__LAST] = {"
-sed -n 's/HASH_ALGO_\(.*\),/[HASH_ALGO_\1] = "\L\1\E",/p' $HASH_INFO
+sed -n 's/HASH_ALGO_\(.*\),/\1 \L\1\E/p' $HASH_INFO | \
+  while read a b; do
+    # Normalize text hash name: if it contains underscore between
+    # digits replace it with a dash, other underscores are removed.
+    b=$(echo "$b" | sed "s/\([0-9]\)_\([0-9]\)/\1-\2/g;s/_//g")
+    printf '\t%-26s = "%s",\n' "[HASH_ALGO_$a]" "$b"
+  done
 echo "};"

src/libimaevm.c +20 -74

index d9ffa13..102d6fc 100644
@@ -63,6 +63,7 @@
 #include "imaevm.h"
 #include "hash_info.h"
 
+/* Named that are primary for OpenSSL. */
 const char *const pkey_hash_algo[PKEY_HASH__LAST] = {
 	[PKEY_HASH_MD4]		= "md4",
 	[PKEY_HASH_MD5]		= "md5",

@@ -72,8 +73,14 @@ const char *const pkey_hash_algo[PKEY_HASH__LAST] = {
 	[PKEY_HASH_SHA384]	= "sha384",
 	[PKEY_HASH_SHA512]	= "sha512",
 	[PKEY_HASH_SHA224]	= "sha224",
-	[PKEY_HASH_STREEBOG_256] = "md_gost12_256,streebog256",
-	[PKEY_HASH_STREEBOG_512] = "md_gost12_512,streebog512",
+	[PKEY_HASH_STREEBOG_256] = "md_gost12_256",
+	[PKEY_HASH_STREEBOG_512] = "md_gost12_512",
+};
+
+/* Names that are primary for the kernel. */
+const char *const pkey_hash_algo_kern[PKEY_HASH__LAST] = {
+	[PKEY_HASH_STREEBOG_256] = "streebog256",
+	[PKEY_HASH_STREEBOG_512] = "streebog512",
 };
 
 /*

@@ -160,9 +167,9 @@ void dump(const void *ptr, int len)
 const char *get_hash_algo_by_id(int algo)
 {
 	if (algo < PKEY_HASH__LAST)
-	    return pkey_hash_algo[algo];
+		return pkey_hash_algo[algo];
 	if (algo < HASH_ALGO__LAST)
-	    return hash_algo_name[algo];
+		return hash_algo_name[algo];
 
 	log_err("digest %d not found\n", algo);
 	return "unknown";

@@ -286,35 +293,6 @@ static int add_dev_hash(struct stat *st, EVP_MD_CTX *ctx)
 	return !EVP_DigestUpdate(ctx, &dev, sizeof(dev));
 }
 
-/* Call EVP_get_digestbyname with provided name and with alias,
- * which is first name in the comma separated list of names
- * in pkey_hash_algo.
- */
-static const EVP_MD *get_digestbyname(const char *name)
-{
-	const EVP_MD *md;
-
-	md = EVP_get_digestbyname(params.hash_algo);
-	if (!md) {
-		char alias[MAX_DIGEST_NAME];
-		int len;
-		int algo_id;
-		const char *algo_alias;
-
-		/* try to get algo by its alias */
-		algo_id = get_hash_algo(params.hash_algo);
-		algo_alias = get_hash_algo_by_id(algo_id);
-		len = strchrnul(algo_alias, ',') - algo_alias;
-		if (len < sizeof(alias)) {
-			memcpy(alias, algo_alias, len);
-			alias[len] = '\0';
-			if (strcmp(params.hash_algo, alias))
-				md = EVP_get_digestbyname(alias);
-		}
-	}
-	return md;
-}
-
 int ima_calc_hash(const char *file, uint8_t *hash)
 {
 	const EVP_MD *md;

@@ -336,7 +314,7 @@ int ima_calc_hash(const char *file, uint8_t *hash)
 		return err;
 	}
 
-	md = get_digestbyname(params.hash_algo);
+	md = EVP_get_digestbyname(params.hash_algo);
 	if (!md) {
 		log_err("EVP_get_digestbyname(%s) failed\n", params.hash_algo);
 		return 1;

@@ -572,42 +550,6 @@ int verify_hash_v2(const char *file, const unsigned char *hash, int size,
 	return 0;
 }
 
-/* compare algo names case insensitively and ignoring separators */
-static int algocmp(const char *a, const char *b)
-{
-	while (*a && *b) {
-		int cha, chb;
-
-		cha = tolower((unsigned char)*a++);
-		if (!isalnum(cha))
-			continue;
-		chb = tolower((unsigned char)*b++);
-		if (!isalnum(chb)) {
-			a--;
-			continue;
-		}
-		if (cha != chb)
-			return -1;
-	}
-	return *a || *b;
-}
-
-static int strmatch(const char *needle, const char *haystack)
-{
-	int len = strlen(needle);
-	const char *p = haystack;
-	const char *t;
-
-	for (t = strchrnul(p, ','); *p; p = t, t = strchrnul(p, ',')) {
-		if (t - p == len &&
-		    !strncmp(needle, p, len))
-			return 0;
-		if (!*t++)
-			break;
-	}
-	return 1;
-}
-
 int get_hash_algo(const char *algo)
 {
 	int i;

@@ -615,15 +557,19 @@ int get_hash_algo(const char *algo)
 	/* first iterate over builtin algorithms */
 	for (i = 0; i < PKEY_HASH__LAST; i++)
 		if (pkey_hash_algo[i] &&
-		    !strmatch(algo, pkey_hash_algo[i]))
+		    !strcmp(algo, pkey_hash_algo[i]))
+			return i;
+
+	for (i = 0; i < PKEY_HASH__LAST; i++)
+		if (pkey_hash_algo_kern[i] &&
+		    !strcmp(algo, pkey_hash_algo_kern[i]))
 			return i;
 
 	/* iterate over algorithms provided by kernel-headers */
-	for (i = 0; i < HASH_ALGO__LAST; i++) {
+	for (i = 0; i < HASH_ALGO__LAST; i++)
 		if (hash_algo_name[i] &&
-		    !algocmp(algo, hash_algo_name[i]))
+		    !strcmp(algo, hash_algo_name[i]))
 			return i;
-	}
 
 	log_info("digest %s not found, fall back to sha1\n", algo);
 	return PKEY_HASH_SHA1;

Mimi,

Quoted 14 lines · Mimi Zohar

Hi Vitaly,

Quoted 10 lines · Vitaly Chikunov

- Make digest name search work just with simple strcmp() and three arrays, dropping strmatch().
- Remove get_digestbyname() which was doing two hash name resolving attempts, reverting to use plain EVP_get_digestbyname(). This will force the user to specify the proper hash name depending on what OpenSSL provides, allowing to specify older hash name in older OpenSSL.
- Improve hash_info parser to produce hash_algo_name[] more resembling what is in the kernel, making algocmp() not needed and removed.
- Fix indent in get_hash_algo_by_id().

Quoted 1 line

Thanks, this is a lot better.  As there isn't a "Signed-off-by", did

Forgot this. I can resend with "Signed-off-by".

Quoted 2 lines

you want to squash this with the original patch - "Extract digest algorithms from hash_info.h"?

Do you mean rebase squash with already upstreamed commit? Did not know this is allowed.

If you want to do it, this probably should not be squashed with "Extract digest algorithms from hash_info.h", but with "Try to load digest by its alias", because it is simplification of this commit.

Quoted 17 lines · Vitaly Chikunov

Quoted 14 lines · Mimi Zohar

Hi Vitaly,

Quoted 10 lines · Vitaly Chikunov

- Make digest name search work just with simple strcmp() and three arrays, dropping strmatch().
- Remove get_digestbyname() which was doing two hash name resolving attempts, reverting to use plain EVP_get_digestbyname(). This will force the user to specify the proper hash name depending on what OpenSSL provides, allowing to specify older hash name in older OpenSSL.
- Improve hash_info parser to produce hash_algo_name[] more resembling what is in the kernel, making algocmp() not needed and removed.
- Fix indent in get_hash_algo_by_id().

Quoted 1 line

Thanks, this is a lot better.  As there isn't a "Signed-off-by", did

Quoted 7 lines

Forgot this. I can resend with "Signed-off-by".

Quoted 2 lines

you want to squash this with the original patch - "Extract digest algorithms from hash_info.h"?

Do you mean rebase squash with already upstreamed commit? Did not know this is allowed.

Agreed, normally it shouldn't be done, but it hasn't been included in a release.  Defining and then removing algocmp() doesn't make sense.

Quoted 1 line

Quoted 3 lines

If you want to do it, this probably should not be squashed with "Extract digest algorithms from hash_info.h", but with "Try to load digest by its alias", because it is simplification of this commit.

Unless there is a reason for keeping these patches separate, please squash them.  It will be easier for anyone reviewing the code.

Thanks!