From: Christoph Hellwig <hch@lst.de>
Date: Tue, 28 Jul 2020 21:33:33 +0000 (+0200)
Subject: modules: inherit TAINT_PROPRIETARY_MODULE
X-Git-Tag: v4.19.191~299
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=2ab98abf0d2a820efa726a5e143133fc5993ed56;p=thirdparty%2Fkernel%2Fstable.git

modules: inherit TAINT_PROPRIETARY_MODULE

commit 262e6ae7081df304fc625cf368d5c2cbba2bb991 upstream.

If a TAINT_PROPRIETARY_MODULE exports symbol, inherit the taint flag
for all modules importing these symbols, and don't allow loading
symbols from TAINT_PROPRIETARY_MODULE modules if the module previously
imported gplonly symbols.  Add a anti-circumvention devices so people
don't accidentally get themselves into trouble this way.

Comment from Greg:
  "Ah, the proven-to-be-illegal "GPL Condom" defense :)"

[jeyu: pr_info -> pr_err and pr_warn as per discussion]
Link: http://lore.kernel.org/r/20200730162957.GA22469@lst.de
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/include/linux/module.h b/include/linux/module.h
index 93392b24b8475..008cfc08a6643 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -359,6 +359,7 @@ struct module {
 	unsigned int num_gpl_syms;
 	const struct kernel_symbol *gpl_syms;
 	const s32 *gpl_crcs;
+	bool using_gplonly_symbols;
 
 #ifdef CONFIG_UNUSED_SYMBOLS
 	/* unused exported symbols. */
diff --git a/kernel/module.c b/kernel/module.c
index 4a2fa74fa7f8f..92d8610742c7d 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1379,6 +1379,25 @@ static inline int same_magic(const char *amagic, const char *bmagic,
 }
 #endif /* CONFIG_MODVERSIONS */
 
+static bool inherit_taint(struct module *mod, struct module *owner)
+{
+	if (!owner || !test_bit(TAINT_PROPRIETARY_MODULE, &owner->taints))
+		return true;
+
+	if (mod->using_gplonly_symbols) {
+		pr_err("%s: module using GPL-only symbols uses symbols from proprietary module %s.\n",
+			mod->name, owner->name);
+		return false;
+	}
+
+	if (!test_bit(TAINT_PROPRIETARY_MODULE, &mod->taints)) {
+		pr_warn("%s: module uses symbols from proprietary module %s, inheriting taint.\n",
+			mod->name, owner->name);
+		set_bit(TAINT_PROPRIETARY_MODULE, &mod->taints);
+	}
+	return true;
+}
+
 /* Resolve a symbol for this module.  I.e. if we find one, record usage. */
 static const struct kernel_symbol *resolve_symbol(struct module *mod,
 						  const struct load_info *info,
@@ -1403,6 +1422,14 @@ static const struct kernel_symbol *resolve_symbol(struct module *mod,
 	if (!sym)
 		goto unlock;
 
+	if (license == GPL_ONLY)
+		mod->using_gplonly_symbols = true;
+
+	if (!inherit_taint(mod, owner)) {
+		sym = NULL;
+		goto getname;
+	}
+
 	if (!check_version(info, name, mod, crc)) {
 		sym = ERR_PTR(-EINVAL);
 		goto getname;