Commit 2f3238ae authored by Rusty Russell's avatar Rusty Russell
Browse files

module: add flags arg to sys_finit_module() 



Thanks to Michael Kerrisk for keeping us honest.  These flags are actually
useful for eliminating the only case where kmod has to mangle a module's
internals: for overriding module versioning.

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Acked-by: default avatarLucas De Marchi <lucas.demarchi@profusion.mobi>
Acked-by: default avatarKees Cook <keescook@chromium.org>
parent 34e1169d

include/linux/syscalls.h

+1 −1
Original line number Diff line number Diff line
@@ -868,5 +868,5 @@ asmlinkage long sys_process_vm_writev(pid_t pid, 


asmlinkage long sys_kcmp(pid_t pid1, pid_t pid2, int type,

			 unsigned long idx1, unsigned long idx2);

asmlinkage long sys_finit_module(int fd, const char __user *uargs);

asmlinkage long sys_finit_module(int fd, const char __user *uargs, int flags);

#endif

include/uapi/linux/module.h

0 → 100644
+8 −0
Original line number Diff line number Diff line 
#ifndef _UAPI_LINUX_MODULE_H

#define _UAPI_LINUX_MODULE_H



/* Flags for sys_finit_module: */

#define MODULE_INIT_IGNORE_MODVERSIONS	1

#define MODULE_INIT_IGNORE_VERMAGIC	2



#endif /* _UAPI_LINUX_MODULE_H */

kernel/module.c

+26 −14
Original line number Diff line number Diff line
@@ -60,6 +60,7 @@ 
#include <linux/pfn.h>

#include <linux/bsearch.h>

#include <linux/fips.h>

#include <uapi/linux/module.h>

#include "module-internal.h"



#define CREATE_TRACE_POINTS
@@ -2553,7 +2554,7 @@ static void free_copy(struct load_info *info) 
	vfree(info->hdr);

}



static int rewrite_section_headers(struct load_info *info)

static int rewrite_section_headers(struct load_info *info, int flags)

{

	unsigned int i;
@@ -2581,6 +2582,9 @@ static int rewrite_section_headers(struct load_info *info) 
	}



	/* Track but don't keep modinfo and version sections. */

	if (flags & MODULE_INIT_IGNORE_MODVERSIONS)

		info->index.vers = 0; /* Pretend no __versions section! */

	else

		info->index.vers = find_sec(info, "__versions");

	info->index.info = find_sec(info, ".modinfo");

	info->sechdrs[info->index.info].sh_flags &= ~(unsigned long)SHF_ALLOC;
@@ -2596,7 +2600,7 @@ static int rewrite_section_headers(struct load_info *info) 
 * Return the temporary module pointer (we'll replace it with the final

 * one when we move the module sections around).

 */

static struct module *setup_load_info(struct load_info *info)

static struct module *setup_load_info(struct load_info *info, int flags)

{

	unsigned int i;

	int err;
@@ -2607,7 +2611,7 @@ static struct module *setup_load_info(struct load_info *info) 
	info->secstrings = (void *)info->hdr

		+ info->sechdrs[info->hdr->e_shstrndx].sh_offset;



	err = rewrite_section_headers(info);

	err = rewrite_section_headers(info, flags);

	if (err)

		return ERR_PTR(err);
@@ -2645,11 +2649,14 @@ static struct module *setup_load_info(struct load_info *info) 
	return mod;

}



static int check_modinfo(struct module *mod, struct load_info *info)

static int check_modinfo(struct module *mod, struct load_info *info, int flags)

{

	const char *modmagic = get_modinfo(info, "vermagic");

	int err;



	if (flags & MODULE_INIT_IGNORE_VERMAGIC)

		modmagic = NULL;



	/* This is allowed: modprobe --force will invalidate it. */

	if (!modmagic) {

		err = try_to_force_load(mod, "bad vermagic");
@@ -2885,18 +2892,18 @@ int __weak module_frob_arch_sections(Elf_Ehdr *hdr, 
	return 0;

}



static struct module *layout_and_allocate(struct load_info *info)

static struct module *layout_and_allocate(struct load_info *info, int flags)

{

	/* Module within temporary copy. */

	struct module *mod;

	Elf_Shdr *pcpusec;

	int err;



	mod = setup_load_info(info);

	mod = setup_load_info(info, flags);

	if (IS_ERR(mod))

		return mod;



	err = check_modinfo(mod, info);

	err = check_modinfo(mod, info, flags);

	if (err)

		return ERR_PTR(err);
@@ -3078,7 +3085,8 @@ static int may_init_module(void) 


/* Allocate and load the module: note that size of section 0 is always

   zero, and we rely on this for optional sections. */

static int load_module(struct load_info *info, const char __user *uargs)

static int load_module(struct load_info *info, const char __user *uargs,

		       int flags)

{

	struct module *mod, *old;

	long err;
@@ -3092,7 +3100,7 @@ static int load_module(struct load_info *info, const char __user *uargs) 
		goto free_copy;



	/* Figure out module layout, and allocate all the memory. */

	mod = layout_and_allocate(info);

	mod = layout_and_allocate(info, flags);

	if (IS_ERR(mod)) {

		err = PTR_ERR(mod);

		goto free_copy;
@@ -3241,10 +3249,10 @@ SYSCALL_DEFINE3(init_module, void __user *, umod, 
	if (err)

		return err;



	return load_module(&info, uargs);

	return load_module(&info, uargs, 0);

}



SYSCALL_DEFINE2(finit_module, int, fd, const char __user *, uargs)

SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags)

{

	int err;

	struct load_info info = { };
@@ -3253,13 +3261,17 @@ SYSCALL_DEFINE2(finit_module, int, fd, const char __user *, uargs) 
	if (err)

		return err;



	pr_debug("finit_module: fd=%d, uargs=%p\n", fd, uargs);

	pr_debug("finit_module: fd=%d, uargs=%p, flags=%i\n", fd, uargs, flags);



	if (flags & ~(MODULE_INIT_IGNORE_MODVERSIONS

		      |MODULE_INIT_IGNORE_VERMAGIC))

		return -EINVAL;



	err = copy_module_from_fd(fd, &info);

	if (err)

		return err;



	return load_module(&info, uargs);

	return load_module(&info, uargs, flags);

}



static inline int within(unsigned long addr, void *start, unsigned long size)

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