The setup_load_info() was actually had ELF validation checks of its own. To later cache useful variables as an secondary step just means looping again over the ELF sections we just validated. We can simply keep tabs of the key sections of interest as we validate the module ELF section in one swoop, so do that and merge the two routines together. Expand a bit on the documentation / intent / goals.
Unified · Split
| @@ -1647,12 +1647,26 @@ static int validate_section_offset(struct load_info *info, Elf_Shdr *shdr) · 1646 unmodified lines | |||
| 1647 | } | 1647 | } |
| 1648 | 1648 | ||
| 1649 | /* | 1649 | /* |
| 1650 | * Sanity checks against invalid binaries, wrong arch, weird elf version. | 1650 | * Check userspace passed ELF module against our expectations, and cache |
| 1651 | * useful variables for further processing as we go. | ||
| 1651 | * | 1652 | * |
| 1652 | * Also do basic validity checks against section offsets and sizes, the | 1653 | * This does basic validity checks against section offsets and sizes, the |
| 1653 | * section name string table, and the indices used for it (sh_name). | 1654 | * section name string table, and the indices used for it (sh_name). |
| 1655 | * | ||
| 1656 | * As a last step, since we're already checking the ELF sections we cache | ||
| 1657 | * useful variables which will be used later for our convenience: | ||
| 1658 | * | ||
| 1659 | * o pointers to section headers | ||
| 1660 | * o cache the modinfo symbol section | ||
| 1661 | * o cache the string symbol section | ||
| 1662 | * o cache the module section | ||
| 1663 | * | ||
| 1664 | * As a last step we set info->mod to the temporary copy of the module in | ||
| 1665 | * info->hdr. The final one will be allocated in move_module(). Any | ||
| 1666 | * modifications we make to our copy of the module will be carried over | ||
| 1667 | * to the final minted module. | ||
| 1654 | */ | 1668 | */ |
| 1655 | static int elf_validity_check(struct load_info *info) | 1669 | static int elf_validity_cache_copy(struct load_info *info, int flags) |
| 1656 | { | 1670 | { |
| 1657 | unsigned int i; | 1671 | unsigned int i; |
| 1658 | Elf_Shdr *shdr, *strhdr; | 1672 | Elf_Shdr *shdr, *strhdr; |
| @@ -1872,6 +1886,13 @@ static int elf_validity_check(struct load_info *info) · 213 unmodified lines | |||
| 1872 | if (!info->name) | 1886 | if (!info->name) |
| 1873 | info->name = info->mod->name; | 1887 | info->name = info->mod->name; |
| 1874 | 1888 | ||
| 1889 | if (flags & MODULE_INIT_IGNORE_MODVERSIONS) | ||
| 1890 | info->index.vers = 0; /* Pretend no __versions section! */ | ||
| 1891 | else | ||
| 1892 | info->index.vers = find_sec(info, "__versions"); | ||
| 1893 | |||
| 1894 | info->index.pcpu = find_pcpusec(info); | ||
| 1895 | |||
| 1875 | return 0; | 1896 | return 0; |
| 1876 | 1897 | ||
| 1877 | no_exec: | 1898 | no_exec: |
| @@ -1984,26 +2005,6 @@ static int rewrite_section_headers(struct load_info *info, int flags) · 106 unmodified lines | |||
| 1984 | return 0; | 2005 | return 0; |
| 1985 | } | 2006 | } |
| 1986 | 2007 | ||
| 1987 | /* | ||
| 1988 | * Set up our basic convenience variables (pointers to section headers, | ||
| 1989 | * search for module section index etc), and do some basic section | ||
| 1990 | * verification. | ||
| 1991 | * | ||
| 1992 | * Set info->mod to the temporary copy of the module in info->hdr. The final one | ||
| 1993 | * will be allocated in move_module(). | ||
| 1994 | */ | ||
| 1995 | static int setup_load_info(struct load_info *info, int flags) | ||
| 1996 | { | ||
| 1997 | if (flags & MODULE_INIT_IGNORE_MODVERSIONS) | ||
| 1998 | info->index.vers = 0; /* Pretend no __versions section! */ | ||
| 1999 | else | ||
| 2000 | info->index.vers = find_sec(info, "__versions"); | ||
| 2001 | |||
| 2002 | info->index.pcpu = find_pcpusec(info); | ||
| 2003 | |||
| 2004 | return 0; | ||
| 2005 | } | ||
| 2006 | |||
| 2007 | /* | 2008 | /* |
| 2008 | * These calls taint the kernel depending certain module circumstances */ | 2009 | * These calls taint the kernel depending certain module circumstances */ |
| 2009 | static void module_augment_kernel_taints(struct module *mod, struct load_info *info) | 2010 | static void module_augment_kernel_taints(struct module *mod, struct load_info *info) |
| @@ -2809,17 +2810,10 @@ static int load_module(struct load_info *info, const char __user *uargs, · 799 unmodified lines | |||
| 2809 | 2810 | ||
| 2810 | /* | 2811 | /* |
| 2811 | * Do basic sanity checks against the ELF header and | 2812 | * Do basic sanity checks against the ELF header and |
| 2812 | * sections. | 2813 | * sections. Cache useful sections and set the |
| 2813 | */ | 2814 | * info->mod to the userspace passed struct module. |
| 2814 | err = elf_validity_check(info); | ||
| 2815 | if (err) | ||
| 2816 | goto free_copy; | ||
| 2817 | |||
| 2818 | /* | ||
| 2819 | * Everything checks out, so set up the section info | ||
| 2820 | * in the info structure. | ||
| 2821 | */ | 2815 | */ |
| 2822 | err = setup_load_info(info, flags); | 2816 | err = elf_validity_cache_copy(info, flags); |
| 2823 | if (err) | 2817 | if (err) |
| 2824 | goto free_copy; | 2818 | goto free_copy; |
| 2825 | 2819 | ||