kbuild: check license compatibility when building modules

Modules that uses GPL symbols can no longer be build with kbuild, the build will fail during the modpost step. When a GPL-incompatible module uses a EXPORT_SYMBOL_GPL_FUTURE symbol then warn during modpost so author are actually notified. The actual license compatibility check is shared with the kernel to make sure it is in sync. Patch originally from: Andreas Gruenbacher <agruen@suse.de> and Ram Pai <linuxram@us.ibm.com> Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

kbuild: check license compatibility when building modules
Modules that uses GPL symbols can no longer be build with kbuild, the build will fail during the modpost step. When a GPL-incompatible module uses a EXPORT_SYMBOL_GPL_FUTURE symbol then warn during modpost so author are actually notified. The actual license compatibility check is shared with the kernel to make sure it is in sync. Patch originally from: Andreas Gruenbacher <agruen@suse.de> and Ram Pai <linuxram@us.ibm.com> Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Sam Ravnborg
1 parent bd5cbcedf4
Showing 4 changed files with 85 additions and 12 deletions Side-by-side Diff
include/linux/license.h
kernel/module.c
scripts/mod/modpost.c
scripts/mod/modpost.h
+#ifndef __LICENSE_H
+#define __LICENSE_H
+
+static inline int license_is_gpl_compatible(const char *license)
+{
+	return (strcmp(license, "GPL") == 0
+		|| strcmp(license, "GPL v2") == 0
+		|| strcmp(license, "GPL and additional rights") == 0
+		|| strcmp(license, "Dual BSD/GPL") == 0
+		|| strcmp(license, "Dual MIT/GPL") == 0
+		|| strcmp(license, "Dual MPL/GPL") == 0);
+}
+
+#endif
@@ -43,6 +43,7 @@
 #include <asm/uaccess.h>
 #include <asm/semaphore.h>
 #include <asm/cacheflush.h>
+#include <linux/license.h>
  
 #if 0
 #define DEBUGP printk
@@ -1246,16 +1247,6 @@
 		if (m == 0)
 			mod->init_text_size = mod->init_size;
 	}
-}
-
-static inline int license_is_gpl_compatible(const char *license)
-{
-	return (strcmp(license, "GPL") == 0
-		|| strcmp(license, "GPL v2") == 0
-		|| strcmp(license, "GPL and additional rights") == 0
-		|| strcmp(license, "Dual BSD/GPL") == 0
-		|| strcmp(license, "Dual MIT/GPL") == 0
-		|| strcmp(license, "Dual MPL/GPL") == 0);
 }
  
 static void set_license(struct module *mod, const char *license)
@@ -13,6 +13,7 @@
  
 #include <ctype.h>
 #include "modpost.h"
+#include "../../include/linux/license.h"
  
 /* Are we using CONFIG_MODVERSIONS? */
 int modversions = 0;
@@ -99,6 +100,7 @@
  
 	/* add to list */
 	mod->name = p;
+	mod->gpl_compatible = -1;
 	mod->next = modules;
 	modules = mod;
  
  
@@ -493,13 +495,18 @@
 	return string;
 }
  
-static char *get_modinfo(void *modinfo, unsigned long modinfo_len,
-			 const char *tag)
+static char *get_next_modinfo(void *modinfo, unsigned long modinfo_len,
+			      const char *tag, char *info)
 {
 	char *p;
 	unsigned int taglen = strlen(tag);
 	unsigned long size = modinfo_len;
  
+	if (info) {
+		size -= info - (char *)modinfo;
+		modinfo = next_string(info, &size);
+	}
+
 	for (p = modinfo; p; p = next_string(p, &size)) {
 		if (strncmp(p, tag, taglen) == 0 && p[taglen] == '=')
 			return p + taglen + 1;
@@ -507,6 +514,13 @@
 	return NULL;
 }
  
+static char *get_modinfo(void *modinfo, unsigned long modinfo_len,
+			 const char *tag)
+
+{
+	return get_next_modinfo(modinfo, modinfo_len, tag, NULL);
+}
+
 /**
  * Test if string s ends in string sub
  * return 0 if match
@@ -981,6 +995,7 @@
 {
 	const char *symname;
 	char *version;
+	char *license;
 	struct module *mod;
 	struct elf_info info = { };
 	Elf_Sym *sym;
@@ -996,6 +1011,18 @@
 		mod->skip = 1;
 	}
  
+	license = get_modinfo(info.modinfo, info.modinfo_len, "license");
+	while (license) {
+		if (license_is_gpl_compatible(license))
+			mod->gpl_compatible = 1;
+		else {
+			mod->gpl_compatible = 0;
+			break;
+		}
+		license = get_next_modinfo(info.modinfo, info.modinfo_len,
+					   "license", license);
+	}
+
 	for (sym = info.symtab_start; sym < info.symtab_stop; sym++) {
 		symname = info.strtab + sym->st_name;
  
@@ -1052,6 +1079,40 @@
 	buf->pos += len;
 }
  
+void check_license(struct module *mod)
+{
+	struct symbol *s, *exp;
+
+	for (s = mod->unres; s; s = s->next) {
+		if (mod->gpl_compatible == 1) {
+			/* GPL-compatible modules may use all symbols */
+			continue;
+		}
+		exp = find_symbol(s->name);
+		if (!exp || exp->module == mod)
+			continue;
+		const char *basename = strrchr(mod->name, '/');
+		if (basename)
+			basename++;
+		switch (exp->export) {
+			case export_gpl:
+				fatal("modpost: GPL-incompatible module %s "
+				      "uses GPL-only symbol '%s'\n",
+				 basename ? basename : mod->name,
+				exp->name);
+				break;
+			case export_gpl_future:
+				warn("modpost: GPL-incompatible module %s "
+				      "uses future GPL-only symbol '%s'\n",
+				      basename ? basename : mod->name,
+				      exp->name);
+				break;
+			case export_plain: /* ignore */ break;
+			case export_unknown: /* ignore */ break;
+		}
+        }
+}
+
 /**
  * Header for the generated file
  **/
@@ -1323,6 +1384,12 @@
  
 	while (optind < argc) {
 		read_symbols(argv[optind++]);
+	}
+
+	for (mod = modules; mod; mod = mod->next) {
+		if (mod->skip)
+			continue;
+		check_license(mod);
 	}
  
 	for (mod = modules; mod; mod = mod->next) {
@@ -100,6 +100,7 @@
 struct module {
 	struct module *next;
 	const char *name;
+	int gpl_compatible;
 	struct symbol *unres;
 	int seen;
 	int skip;
	1	+#ifndef __LICENSE_H
	2	+#define __LICENSE_H
	3	+
	4	+static inline int license_is_gpl_compatible(const char *license)
	5	+{
	6	+ return (strcmp(license, "GPL") == 0
	7	+ \|\| strcmp(license, "GPL v2") == 0
	8	+ \|\| strcmp(license, "GPL and additional rights") == 0
	9	+ \|\| strcmp(license, "Dual BSD/GPL") == 0
	10	+ \|\| strcmp(license, "Dual MIT/GPL") == 0
	11	+ \|\| strcmp(license, "Dual MPL/GPL") == 0);
	12	+}
	13	+
	14	+#endif
...	...	@@ -43,6 +43,7 @@
43	43	#include <asm/uaccess.h>
44	44	#include <asm/semaphore.h>
45	45	#include <asm/cacheflush.h>
	46	+#include <linux/license.h>
46	47
47	48	#if 0
48	49	#define DEBUGP printk
...	...	@@ -1246,16 +1247,6 @@
1246	1247	if (m == 0)
1247	1248	mod->init_text_size = mod->init_size;
1248	1249	}
1249		-}
1250		-
1251		-static inline int license_is_gpl_compatible(const char *license)
1252		-{
1253		- return (strcmp(license, "GPL") == 0
1254		- \|\| strcmp(license, "GPL v2") == 0
1255		- \|\| strcmp(license, "GPL and additional rights") == 0
1256		- \|\| strcmp(license, "Dual BSD/GPL") == 0
1257		- \|\| strcmp(license, "Dual MIT/GPL") == 0
1258		- \|\| strcmp(license, "Dual MPL/GPL") == 0);
1259	1250	}
1260	1251
1261	1252	static void set_license(struct module mod, const char license)
...	...	@@ -13,6 +13,7 @@
13	13
14	14	#include <ctype.h>
15	15	#include "modpost.h"
	16	+#include "../../include/linux/license.h"
16	17
17	18	/* Are we using CONFIG_MODVERSIONS? */
18	19	int modversions = 0;
...	...	@@ -99,6 +100,7 @@
99	100
100	101	/* add to list */
101	102	mod->name = p;
	103	+ mod->gpl_compatible = -1;
102	104	mod->next = modules;
103	105	modules = mod;
104	106
105	107
...	...	@@ -493,13 +495,18 @@
493	495	return string;
494	496	}
495	497
496		-static char get_modinfo(void modinfo, unsigned long modinfo_len,
497		- const char *tag)
	498	+static char get_next_modinfo(void modinfo, unsigned long modinfo_len,
	499	+ const char tag, char info)
498	500	{
499	501	char *p;
500	502	unsigned int taglen = strlen(tag);
501	503	unsigned long size = modinfo_len;
502	504
	505	+ if (info) {
	506	+ size -= info - (char *)modinfo;
	507	+ modinfo = next_string(info, &size);
	508	+ }
	509	+
503	510	for (p = modinfo; p; p = next_string(p, &size)) {
504	511	if (strncmp(p, tag, taglen) == 0 && p[taglen] == '=')
505	512	return p + taglen + 1;
...	...	@@ -507,6 +514,13 @@
507	514	return NULL;
508	515	}
509	516
	517	+static char get_modinfo(void modinfo, unsigned long modinfo_len,
	518	+ const char *tag)
	519	+
	520	+{
	521	+ return get_next_modinfo(modinfo, modinfo_len, tag, NULL);
	522	+}
	523	+
510	524	/**
511	525	* Test if string s ends in string sub
512	526	* return 0 if match
...	...	@@ -981,6 +995,7 @@
981	995	{
982	996	const char *symname;
983	997	char *version;
	998	+ char *license;
984	999	struct module *mod;
985	1000	struct elf_info info = { };
986	1001	Elf_Sym *sym;
...	...	@@ -996,6 +1011,18 @@
996	1011	mod->skip = 1;
997	1012	}
998	1013
	1014	+ license = get_modinfo(info.modinfo, info.modinfo_len, "license");
	1015	+ while (license) {
	1016	+ if (license_is_gpl_compatible(license))
	1017	+ mod->gpl_compatible = 1;
	1018	+ else {
	1019	+ mod->gpl_compatible = 0;
	1020	+ break;
	1021	+ }
	1022	+ license = get_next_modinfo(info.modinfo, info.modinfo_len,
	1023	+ "license", license);
	1024	+ }
	1025	+
999	1026	for (sym = info.symtab_start; sym < info.symtab_stop; sym++) {
1000	1027	symname = info.strtab + sym->st_name;
1001	1028
...	...	@@ -1052,6 +1079,40 @@
1052	1079	buf->pos += len;
1053	1080	}
1054	1081
	1082	+void check_license(struct module *mod)
	1083	+{
	1084	+ struct symbol s, exp;
	1085	+
	1086	+ for (s = mod->unres; s; s = s->next) {
	1087	+ if (mod->gpl_compatible == 1) {
	1088	+ /* GPL-compatible modules may use all symbols */
	1089	+ continue;
	1090	+ }
	1091	+ exp = find_symbol(s->name);
	1092	+ if (!exp \|\| exp->module == mod)
	1093	+ continue;
	1094	+ const char *basename = strrchr(mod->name, '/');
	1095	+ if (basename)
	1096	+ basename++;
	1097	+ switch (exp->export) {
	1098	+ case export_gpl:
	1099	+ fatal("modpost: GPL-incompatible module %s "
	1100	+ "uses GPL-only symbol '%s'\n",
	1101	+ basename ? basename : mod->name,
	1102	+ exp->name);
	1103	+ break;
	1104	+ case export_gpl_future:
	1105	+ warn("modpost: GPL-incompatible module %s "
	1106	+ "uses future GPL-only symbol '%s'\n",
	1107	+ basename ? basename : mod->name,
	1108	+ exp->name);
	1109	+ break;
	1110	+ case export_plain: /* ignore */ break;
	1111	+ case export_unknown: /* ignore */ break;
	1112	+ }
	1113	+ }
	1114	+}
	1115	+
1055	1116	/**
1056	1117	* Header for the generated file
1057	1118	**/
...	...	@@ -1323,6 +1384,12 @@
1323	1384
1324	1385	while (optind < argc) {
1325	1386	read_symbols(argv[optind++]);
	1387	+ }
	1388	+
	1389	+ for (mod = modules; mod; mod = mod->next) {
	1390	+ if (mod->skip)
	1391	+ continue;
	1392	+ check_license(mod);
1326	1393	}
1327	1394
1328	1395	for (mod = modules; mod; mod = mod->next) {
...	...	@@ -100,6 +100,7 @@
100	100	struct module {
101	101	struct module *next;
102	102	const char *name;
	103	+ int gpl_compatible;
103	104	struct symbol *unres;
104	105	int seen;
105	106	int skip;