linux-kernel - [PATCH v2 1/2] module: Pass struct load

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Date:   Fri, 21 Apr 2017 15:35:26 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Jessica Yu <jeyu@...hat.com>
Cc:     Kees Cook <keescook@...omium.org>,
        Rusty Russell <rusty@...tcorp.com.au>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Heinrich Schuchardt <xypron.glpk@....de>,
        Nicholas Piggin <npiggin@...il.com>,
        Chris Metcalf <cmetcalf@...lanox.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/2] module: Pass struct load_info into symbol checks

Since we're already using values from struct load_info, just pass this
pointer in directly and use what's needed as we need it. This allows us
to access future fields in struct load_info too.

Signed-off-by: Kees Cook <keescook@...omium.org>
---
 kernel/module.c | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/kernel/module.c b/kernel/module.c
index 7eba6dea4f41..ed6cf2367217 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1257,12 +1257,13 @@ static u32 resolve_rel_crc(const s32 *crc)
 	return *(u32 *)((void *)crc + *crc);
 }
 
-static int check_version(Elf_Shdr *sechdrs,
-			 unsigned int versindex,
+static int check_version(const struct load_info *info,
 			 const char *symname,
 			 struct module *mod,
 			 const s32 *crc)
 {
+	Elf_Shdr *sechdrs = info->sechdrs;
+	unsigned int versindex = info->index.vers;
 	unsigned int i, num_versions;
 	struct modversion_info *versions;
 
@@ -1305,8 +1306,7 @@ static int check_version(Elf_Shdr *sechdrs,
 	return 0;
 }
 
-static inline int check_modstruct_version(Elf_Shdr *sechdrs,
-					  unsigned int versindex,
+static inline int check_modstruct_version(const struct load_info *info,
 					  struct module *mod)
 {
 	const s32 *crc;
@@ -1322,8 +1322,8 @@ static inline int check_modstruct_version(Elf_Shdr *sechdrs,
 		BUG();
 	}
 	preempt_enable();
-	return check_version(sechdrs, versindex,
-			     VMLINUX_SYMBOL_STR(module_layout), mod, crc);
+	return check_version(info, VMLINUX_SYMBOL_STR(module_layout),
+			     mod, crc);
 }
 
 /* First part is kernel version, which we ignore if module has crcs. */
@@ -1337,8 +1337,7 @@ static inline int same_magic(const char *amagic, const char *bmagic,
 	return strcmp(amagic, bmagic) == 0;
 }
 #else
-static inline int check_version(Elf_Shdr *sechdrs,
-				unsigned int versindex,
+static inline int check_version(const struct load_info *info,
 				const char *symname,
 				struct module *mod,
 				const s32 *crc)
@@ -1346,8 +1345,7 @@ static inline int check_version(Elf_Shdr *sechdrs,
 	return 1;
 }
 
-static inline int check_modstruct_version(Elf_Shdr *sechdrs,
-					  unsigned int versindex,
+static inline int check_modstruct_version(const struct load_info *info,
 					  struct module *mod)
 {
 	return 1;
@@ -1383,7 +1381,7 @@ static const struct kernel_symbol *resolve_symbol(struct module *mod,
 	if (!sym)
 		goto unlock;
 
-	if (!check_version(info->sechdrs, info->index.vers, name, mod, crc)) {
+	if (!check_version(info, name, mod, crc)) {
 		sym = ERR_PTR(-EINVAL);
 		goto getname;
 	}
@@ -2950,7 +2948,7 @@ static struct module *setup_load_info(struct load_info *info, int flags)
 	info->index.pcpu = find_pcpusec(info);
 
 	/* Check module struct version now, before we try to use module. */
-	if (!check_modstruct_version(info->sechdrs, info->index.vers, mod))
+	if (!check_modstruct_version(info, mod))
 		return ERR_PTR(-ENOEXEC);
 
 	return mod;
-- 
2.7.4