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module: refactor out section header rewriting

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Put all the "rewrite and check section headers" in one place.  This
adds another iteration over the sections, but it's far clearer.  We
iterate once for every find_section() so we already iterate over many
times.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2010-08-05 12:59:06 -06:00
parent 3264d3f9dd
commit 8b5f61a795
1 changed files with 45 additions and 25 deletions
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70
kernel/module.c
View file

@ -2158,6 +2158,7 @@ struct load_info {
} index;
};
/* Sets info->hdr and info->len. */
static int copy_and_check(struct load_info *info, const void __user *umod, unsigned long len)
{
int err;
@ -2199,6 +2200,39 @@ static int copy_and_check(struct load_info *info, const void __user *umod, unsig
return err;
}
static int rewrite_section_headers(struct load_info *info)
{
unsigned int i;
/* This should always be true, but let's be sure. */
info->sechdrs[0].sh_addr = 0;
for (i = 1; i < info->hdr->e_shnum; i++) {
Elf_Shdr *shdr = &info->sechdrs[i];
if (shdr->sh_type != SHT_NOBITS
&& info->len < shdr->sh_offset + shdr->sh_size) {
printk(KERN_ERR "Module len %lu truncated\n",
info->len);
return -ENOEXEC;
}
/* Mark all sections sh_addr with their address in the
temporary image. */
shdr->sh_addr = (size_t)info->hdr + shdr->sh_offset;
#ifndef CONFIG_MODULE_UNLOAD
/* Don't load .exit sections */
if (strstarts(info->secstrings+shdr->sh_name, ".exit"))
shdr->sh_flags &= ~(unsigned long)SHF_ALLOC;
#endif
/* Don't keep modinfo and version sections. */
if (!strcmp(info->secstrings+shdr->sh_name, "__versions")
|| !strcmp(info->secstrings+shdr->sh_name, ".modinfo"))
shdr->sh_flags &= ~(unsigned long)SHF_ALLOC;
}
return 0;
}
/*
* Set up our basic convenience variables (pointers to section headers,
* search for module section index etc), and do some basic section
@ -2210,33 +2244,27 @@ static int copy_and_check(struct load_info *info, const void __user *umod, unsig
static struct module *setup_load_info(struct load_info *info)
{
unsigned int i;
int err;
struct module *mod;
/* Set up the convenience variables */
info->sechdrs = (void *)info->hdr + info->hdr->e_shoff;
info->secstrings = (void *)info->hdr + info->sechdrs[info->hdr->e_shstrndx].sh_offset;
info->sechdrs[0].sh_addr = 0;
info->secstrings = (void *)info->hdr
+ info->sechdrs[info->hdr->e_shstrndx].sh_offset;
err = rewrite_section_headers(info);
if (err)
return ERR_PTR(err);
/* Find internal symbols and strings. */
for (i = 1; i < info->hdr->e_shnum; i++) {
if (info->sechdrs[i].sh_type != SHT_NOBITS
&& info->len < info->sechdrs[i].sh_offset + info->sechdrs[i].sh_size)
goto truncated;
/* Mark all sections sh_addr with their address in the
temporary image. */
info->sechdrs[i].sh_addr = (size_t)info->hdr + info->sechdrs[i].sh_offset;
/* Internal symbols and strings. */
if (info->sechdrs[i].sh_type == SHT_SYMTAB) {
info->index.sym = i;
info->index.str = info->sechdrs[i].sh_link;
info->strtab = (char *)info->hdr + info->sechdrs[info->index.str].sh_offset;
info->strtab = (char *)info->hdr
+ info->sechdrs[info->index.str].sh_offset;
break;
}
#ifndef CONFIG_MODULE_UNLOAD
/* Don't load .exit sections */
if (strstarts(info->secstrings+info->sechdrs[i].sh_name, ".exit"))
info->sechdrs[i].sh_flags &= ~(unsigned long)SHF_ALLOC;
#endif
}
info->index.mod = find_sec(info->hdr, info->sechdrs, info->secstrings,
@ -2258,19 +2286,11 @@ static struct module *setup_load_info(struct load_info *info)
info->index.info = find_sec(info->hdr, info->sechdrs, info->secstrings, ".modinfo");
info->index.pcpu = find_pcpusec(info->hdr, info->sechdrs, info->secstrings);
/* Don't keep modinfo and version sections. */
info->sechdrs[info->index.info].sh_flags &= ~(unsigned long)SHF_ALLOC;
info->sechdrs[info->index.vers].sh_flags &= ~(unsigned long)SHF_ALLOC;
/* Check module struct version now, before we try to use module. */
if (!check_modstruct_version(info->sechdrs, info->index.vers, mod))
return ERR_PTR(-ENOEXEC);
return mod;
truncated:
printk(KERN_ERR "Module len %lu truncated\n", info->len);
return ERR_PTR(-ENOEXEC);
}
static int check_modinfo(struct module *mod,