lkml.org 
[lkml]   [2007]   [Feb]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    SubjectRe: [PATCH/RFC] alternative aproach to: Ban module license tag string termination trick
    On Sat, Feb 03, 2007 at 03:08:14AM +0100, Bodo Eggert wrote:
    > This patch changes the module license handling code to:
    > - prevent the "GPL\0 for nothing"-trick

    You can achieve this effect without changing the existing module
    format, and it's far more difficult to bypass with build-with-
    modified module.h tricks.

    --- a/kernel/module.c Mon Nov 7 19:58:31 2005
    +++ b/kernel/module.c Mon Dec 5 19:39:36 2005
    @@ -286,6 +286,24 @@ static unsigned long find_local_symbol(E
    return 0;
    }

    +static int check_modinfo_objects(Elf_Shdr *sechdrs,
    + unsigned int symindex,
    + unsigned int infoindex)
    +{
    + unsigned int i;
    + Elf_Sym *sym = (void *)sechdrs[symindex].sh_addr;
    + char *info = (char *)sechdrs[infoindex].sh_addr;
    +
    + for (i = 1; i < sechdrs[symindex].sh_size/sizeof(*sym); i++) {
    + if (sym[i].st_shndx == infoindex &&
    + ELF_ST_TYPE(sym[i].st_info) == STT_OBJECT) {
    + if (strlen(info + sym[i].st_value) + 1 != sym[i].st_size)
    + return -ENOEXEC;
    + }
    + }
    + return 0;
    +}
    +
    /* Search for module by name: must hold module_mutex. */
    static struct module *find_module(const char *name)
    {
    @@ -1674,6 +1692,10 @@ static struct module *load_module(void _
    goto free_hdr;
    }

    + err = check_modinfo_objects(sechdrs, symindex, infoindex);
    + if (err)
    + goto free_hdr;
    +
    modmagic = get_modinfo(sechdrs, infoindex, "vermagic");
    /* This is allowed: modprobe --force will invalidate it. */
    if (!modmagic) {
    --
    Russell King
    Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
    maintainer of:
    -
    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/

    \
     
     \ /
      Last update: 2007-02-03 09:17    [W:0.024 / U:0.416 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site