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Commit 40dd2560 authored by Rusty Russell's avatar Rusty Russell
Browse files

module: refactor load_module part 3 



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

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 65b8a9b4

kernel/module.c

+75 −47
Original line number Diff line number Diff line
@@ -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);