Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758064AbZJTAMx (ORCPT ); Mon, 19 Oct 2009 20:12:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758017AbZJTAMw (ORCPT ); Mon, 19 Oct 2009 20:12:52 -0400 Received: from claw.goop.org ([74.207.240.146]:49304 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756060AbZJTAMv (ORCPT ); Mon, 19 Oct 2009 20:12:51 -0400 Message-ID: <4ADD0086.9060304@goop.org> Date: Tue, 20 Oct 2009 09:12:54 +0900 From: Jeremy Fitzhardinge User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.4pre) Gecko/20090922 Fedora/3.0-2.7.b4.fc11 Lightning/1.0pre Thunderbird/3.0b4 MIME-Version: 1.0 To: "Ryan C. Gordon" CC: linux-kernel@vger.kernel.org Subject: Re: [RFC][PATCH 2/2] binfmt_elf: FatELF support for kernel modules. References: In-Reply-To: X-Enigmail-Version: 0.97a Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4988 Lines: 143 On 10/19/09 23:41, Ryan C. Gordon wrote: > Allows kernel modules to be FatELF binaries. > > Details, rationale, tools, and patches for handling FatELF binaries can be > found at http://icculus.org/fatelf/ > > Please note that this requires an updated depmod and modprobe to be truly > effective, but an unmodified insmod can work with FatELF binaries. > This seems much more dubious. It would only encourage more binary modules, which we're not very keen on doing. J > Signed-off-by: Ryan C. Gordon > --- > kernel/module.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++++---- > 1 files changed, 67 insertions(+), 5 deletions(-) > > diff --git a/kernel/module.c b/kernel/module.c > index 8b7d880..cda8f79 100644 > --- a/kernel/module.c > +++ b/kernel/module.c > @@ -2066,13 +2066,69 @@ static inline void kmemleak_load_module(struct module *mod, Elf_Ehdr *hdr, > } > #endif > > +/* > + * See if we're a valid FatELF binary, find the right record, and > + * return the offset of that record within the binary. Returns NULL if there's > + * a problem, or a pointer to the real ELF header if we're okay. > + * If we don't see the FatELF magic number, we assume this is a regular ELF > + * binary and let the regular ELF checks handle it. > + * > + * This is a simplified version of examine_fatelf in fs/binfmt_elf.c > + */ > +static Elf_Ehdr *examine_fatelf_module(const unsigned char *hdr, > + const unsigned long len) > +{ > + Elf_Ehdr elf; > + int records, i; > + const fatelf_hdr *fatelf = (const fatelf_hdr *) hdr; > + > + if (likely(le32_to_cpu(fatelf->magic) != FATELF_MAGIC)) { > + return (Elf_Ehdr *) hdr; /* not FatELF; not an error. */ > + } else if (unlikely(le16_to_cpu(fatelf->version) != 1)) { > + return NULL; /* Unrecognized format version. */ > + } > + > + memset(&elf, 0, sizeof (elf)); > + > + records = (int) fatelf->num_records; /* uint8, no byteswap needed */ > + for (i = 0; i < records; i++) { > + const fatelf_record *record = &fatelf->records[i]; > + > + /* Fill in the data elf_check_arch() might care about. */ > + elf.e_ident[EI_OSABI] = record->osabi; > + elf.e_ident[EI_CLASS] = record->word_size; > + elf.e_ident[EI_DATA] = record->byte_order; > + elf.e_machine = le16_to_cpu(record->machine); > + > + if (likely(!elf_check_arch(&elf))) { > + continue; /* Unsupported CPU architecture. */ > + } else { > + const __u64 rec_offset = le64_to_cpu(record->offset); > + const __u64 rec_size = le64_to_cpu(record->size); > + const __u64 end_offset = rec_offset + rec_size; > + const unsigned long uloff = (unsigned long) rec_offset; > + > + if (unlikely(end_offset < rec_offset)) { > + continue; /* overflow (corrupt file?)... */ > + } else if (unlikely(end_offset > len)) { > + continue; /* past EOF. */ > + } > + > + return (Elf_Ehdr *) (hdr + uloff); > + } > + } > + > + return NULL; /* no binaries we could use. */ > +} > + > /* Allocate and load the module: note that size of section 0 is always > zero, and we rely on this for optional sections. */ > static noinline struct module *load_module(void __user *umod, > unsigned long len, > const char __user *uargs) > { > - Elf_Ehdr *hdr; > + Elf_Ehdr *hdr_alloc; /* returned from vmalloc */ > + Elf_Ehdr *hdr; /* adjusted hdr_alloc for FatELF */ > Elf_Shdr *sechdrs; > char *secstrings, *args, *modmagic, *strtab = NULL; > char *staging; > @@ -2094,14 +2150,20 @@ static noinline struct module *load_module(void __user *umod, > > /* Suck in entire file: we'll want most of it. */ > /* vmalloc barfs on "unusual" numbers. Check here */ > - if (len > 64 * 1024 * 1024 || (hdr = vmalloc(len)) == NULL) > + if (len > 64 * 1024 * 1024 || (hdr_alloc = vmalloc(len)) == NULL) > return ERR_PTR(-ENOMEM); > > - if (copy_from_user(hdr, umod, len) != 0) { > + if (copy_from_user(hdr_alloc, umod, len) != 0) { > err = -EFAULT; > goto free_hdr; > } > > + hdr = examine_fatelf_module((unsigned char *) hdr_alloc, len); > + if (hdr == NULL) { > + err = -ENOEXEC; > + goto free_hdr; > + } > + > /* Sanity checks against insmoding binaries or wrong arch, > weird elf version */ > if (memcmp(hdr->e_ident, ELFMAG, SELFMAG) != 0 > @@ -2505,7 +2567,7 @@ static noinline struct module *load_module(void __user *umod, > add_notes_attrs(mod, hdr->e_shnum, secstrings, sechdrs); > > /* Get rid of temporary copy */ > - vfree(hdr); > + vfree(hdr_alloc); > > trace_module_load(mod); > > @@ -2538,7 +2600,7 @@ static noinline struct module *load_module(void __user *umod, > kfree(args); > kfree(strmap); > free_hdr: > - vfree(hdr); > + vfree(hdr_alloc); > return ERR_PTR(err); > > truncated: > -- 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/