Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932525Ab2JWCC1 (ORCPT ); Mon, 22 Oct 2012 22:02:27 -0400 Received: from ozlabs.org ([203.10.76.45]:35129 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756500Ab2JWCA4 (ORCPT ); Mon, 22 Oct 2012 22:00:56 -0400 From: Rusty Russell To: mtk.manpages@gmail.com Cc: "H. Peter Anvin" , Kees Cook , linux-kernel@vger.kernel.org, Lucas De Marchi , jonathon@jonmasters.org Subject: Re: [PATCH 1/4] module: add syscall to load module from fd In-Reply-To: References: <1348179300-11653-1-git-send-email-keescook@chromium.org> <50749DE8.7010703@zytor.com> <5074A0AB.8040207@zytor.com> <87d30o7iy6.fsf@rustcorp.com.au> <87ipa8o4mn.fsf@rustcorp.com.au> User-Agent: Notmuch/0.14 (http://notmuchmail.org) Emacs/23.4.1 (i686-pc-linux-gnu) Date: Mon, 22 Oct 2012 18:09:41 +1030 Message-ID: <87sj97hs5e.fsf@rustcorp.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6399 Lines: 197 "Michael Kerrisk (man-pages)" writes: >> FIX: add flags arg to sys_finit_module() >> >> Thanks to Michael Kerrisk for keeping us honest. > > w00t! Thanks, Rusty ;-). > > Acked-by: Michael Kerrisk Here's the version I ended up with when I added two flags. Lucas, is this useful to you? BTW Michael: why aren't the syscall man pages in the kernel source? Thanks, Rusty. 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: Rusty Russell diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index 32bc035..8cf7b50 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -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 diff --git a/include/uapi/linux/module.h b/include/uapi/linux/module.h new file mode 100644 index 0000000..38da425 --- /dev/null +++ b/include/uapi/linux/module.h @@ -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 */ diff --git a/kernel/module.c b/kernel/module.c index 261bf82..55b49cd 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -61,6 +61,7 @@ #include #include #include +#include #include "module-internal.h" #define CREATE_TRACE_POINTS @@ -2569,7 +2570,7 @@ 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; @@ -2597,7 +2598,10 @@ 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; @@ -2612,7 +2617,7 @@ 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; @@ -2623,7 +2628,7 @@ 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); @@ -2661,11 +2666,14 @@ 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"); @@ -2901,18 +2909,18 @@ 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); @@ -3094,7 +3102,8 @@ 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; @@ -3108,7 +3117,7 @@ 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; @@ -3257,10 +3269,10 @@ 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 = { }; @@ -3269,13 +3281,17 @@ 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) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/