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module: refactor load_module part 3

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Extract out the allocation and copying in from userspace, and the
first set of modinfo checks.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2010-08-05 12:59:03 -06:00
parent 65b8a9b4d5
commit 40dd2560ec
1 changed files with 75 additions and 47 deletions
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120
kernel/module.c
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@ -1803,7 +1803,7 @@ static char *next_string(char *string, unsigned long *secsize)
return string;
}
static char *get_modinfo(Elf_Shdr *sechdrs,
static char *get_modinfo(const Elf_Shdr *sechdrs,
unsigned int info,
const char *tag)
{
@ -2109,6 +2109,73 @@ static inline void kmemleak_load_module(struct module *mod, Elf_Ehdr *hdr,
}
#endif
static int copy_and_check(Elf_Ehdr **hdrp,
const void __user *umod, unsigned long len)
{
int err;
Elf_Ehdr *hdr;
if (len < sizeof(*hdr))
return -ENOEXEC;
/* Suck in entire file: we'll want most of it. */
/* vmalloc barfs on "unusual" numbers. Check here */
if (len > 64 * 1024 * 1024 || (hdr = *hdrp = vmalloc(len)) == NULL)
return -ENOMEM;
if (copy_from_user(hdr, umod, len) != 0) {
err = -EFAULT;
goto free_hdr;
}
/* Sanity checks against insmoding binaries or wrong arch,
weird elf version */
if (memcmp(hdr->e_ident, ELFMAG, SELFMAG) != 0
|| hdr->e_type != ET_REL
|| !elf_check_arch(hdr)
|| hdr->e_shentsize != sizeof(Elf_Shdr)) {
err = -ENOEXEC;
goto free_hdr;
}
if (len < hdr->e_shoff + hdr->e_shnum * sizeof(Elf_Shdr)) {
err = -ENOEXEC;
goto free_hdr;
}
return 0;
free_hdr:
vfree(hdr);
return err;
}
static int check_modinfo(struct module *mod,
const Elf_Shdr *sechdrs,
unsigned int infoindex, unsigned int versindex)
{
const char *modmagic = get_modinfo(sechdrs, infoindex, "vermagic");
int err;
/* This is allowed: modprobe --force will invalidate it. */
if (!modmagic) {
err = try_to_force_load(mod, "bad vermagic");
if (err)
return err;
} else if (!same_magic(modmagic, vermagic, versindex)) {
printk(KERN_ERR "%s: version magic '%s' should be '%s'\n",
mod->name, modmagic, vermagic);
return -ENOEXEC;
}
if (get_modinfo(sechdrs, infoindex, "staging")) {
add_taint_module(mod, TAINT_CRAP);
printk(KERN_WARNING "%s: module is from the staging directory,"
" the quality is unknown, you have been warned.\n",
mod->name);
}
return 0;
}
static void find_module_sections(struct module *mod, Elf_Ehdr *hdr,
Elf_Shdr *sechdrs, const char *secstrings)
{
@ -2246,14 +2313,13 @@ static noinline struct module *load_module(void __user *umod,
{
Elf_Ehdr *hdr;
Elf_Shdr *sechdrs;
char *secstrings, *args, *modmagic, *strtab = NULL;
char *staging;
char *secstrings, *args, *strtab = NULL;
unsigned int i;
unsigned int symindex = 0;
unsigned int strindex = 0;
unsigned int modindex, versindex, infoindex, pcpuindex;
struct module *mod;
long err = 0;
long err;
unsigned long symoffs, stroffs, *strmap;
void __percpu *percpu;
struct _ddebug *debug = NULL;
@ -2263,31 +2329,10 @@ static noinline struct module *load_module(void __user *umod,
DEBUGP("load_module: umod=%p, len=%lu, uargs=%p\n",
umod, len, uargs);
if (len < sizeof(*hdr))
return ERR_PTR(-ENOEXEC);
/* 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)
return ERR_PTR(-ENOMEM);
if (copy_from_user(hdr, umod, len) != 0) {
err = -EFAULT;
goto free_hdr;
}
/* Sanity checks against insmoding binaries or wrong arch,
weird elf version */
if (memcmp(hdr->e_ident, ELFMAG, SELFMAG) != 0
|| hdr->e_type != ET_REL
|| !elf_check_arch(hdr)
|| hdr->e_shentsize != sizeof(*sechdrs)) {
err = -ENOEXEC;
goto free_hdr;
}
if (len < hdr->e_shoff + hdr->e_shnum * sizeof(Elf_Shdr))
goto truncated;
err = copy_and_check(&hdr, umod, len);
if (err)
return ERR_PTR(err);
/* Convenience variables */
sechdrs = (void *)hdr + hdr->e_shoff;
@ -2347,26 +2392,9 @@ static noinline struct module *load_module(void __user *umod,
goto free_hdr;
}
modmagic = get_modinfo(sechdrs, infoindex, "vermagic");
/* This is allowed: modprobe --force will invalidate it. */
if (!modmagic) {
err = try_to_force_load(mod, "bad vermagic");
err = check_modinfo(mod, sechdrs, infoindex, versindex);
if (err)
goto free_hdr;
} else if (!same_magic(modmagic, vermagic, versindex)) {
printk(KERN_ERR "%s: version magic '%s' should be '%s'\n",
mod->name, modmagic, vermagic);
err = -ENOEXEC;
goto free_hdr;
}
staging = get_modinfo(sechdrs, infoindex, "staging");
if (staging) {
add_taint_module(mod, TAINT_CRAP);
printk(KERN_WARNING "%s: module is from the staging directory,"
" the quality is unknown, you have been warned.\n",
mod->name);
}
/* Now copy in args */
args = strndup_user(uargs, ~0UL >> 1);