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module: add flags arg to sys_finit_module()

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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: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Acked-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Rusty Russell 2012-10-22 18:09:41 +10:30
parent 34e1169d99
commit 2f3238aebe
3 changed files with 35 additions and 15 deletions
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2
include/linux/syscalls.h
View file

@ -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

8
include/uapi/linux/module.h Normal file
View file

@ -0,0 +1,8 @@
#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 */

40
kernel/module.c
View file

@ -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;
@ -2581,7 +2582,10 @@ static int rewrite_section_headers(struct load_info *info)
}
/* Track but don't keep modinfo and version sections. */
info->index.vers = find_sec(info, "__versions");
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;
info->sechdrs[info->index.vers].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)