From 1bb49db9919a4d4186cba288930e7026d8f7ec96 Mon Sep 17 00:00:00 2001 From: Luis Chamberlain Date: Sun, 19 Mar 2023 14:35:40 -0700 Subject: [PATCH] module: move more elf validity checks to elf_validity_check() The symbol and strings section validation currently happen in setup_load_info() but since they are also doing validity checks move this to elf_validity_check(). Signed-off-by: Luis Chamberlain --- kernel/module/main.c | 79 ++++++++++++++++++++++++-------------------- 1 file changed, 44 insertions(+), 35 deletions(-) diff --git a/kernel/module/main.c b/kernel/module/main.c index fbe62d1625bc..84a7f96cf35a 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -1658,6 +1658,8 @@ static int elf_validity_check(struct load_info *info) Elf_Shdr *shdr, *strhdr; int err; unsigned int num_mod_secs = 0, mod_idx; + unsigned int num_info_secs = 0, info_idx; + unsigned int num_sym_secs = 0, sym_idx; if (info->len < sizeof(*(info->hdr))) { pr_err("Invalid ELF header len %lu\n", info->len); @@ -1761,6 +1763,8 @@ static int elf_validity_check(struct load_info *info) info->hdr->e_shnum); goto no_exec; } + num_sym_secs++; + sym_idx = i; fallthrough; default: err = validate_section_offset(info, shdr); @@ -1773,6 +1777,10 @@ static int elf_validity_check(struct load_info *info) ".gnu.linkonce.this_module") == 0) { num_mod_secs++; mod_idx = i; + } else if (strcmp(info->secstrings + shdr->sh_name, + ".modinfo") == 0) { + num_info_secs++; + info_idx = i; } if (shdr->sh_flags & SHF_ALLOC) { @@ -1786,6 +1794,27 @@ static int elf_validity_check(struct load_info *info) } } + if (num_info_secs > 1) { + pr_err("Only one .modinfo section must exist.\n"); + goto no_exec; + } else if (num_info_secs == 1) { + /* Try to find a name early so we can log errors with a module name */ + info->index.info = info_idx; + info->name = get_modinfo(info, "name"); + } + + if (num_sym_secs != 1) { + pr_warn("%s: module has no symbols (stripped?)\n", + info->name ?: "(missing .modinfo section or name field)"); + goto no_exec; + } + + /* Sets internal symbols and strings. */ + info->index.sym = sym_idx; + shdr = &info->sechdrs[sym_idx]; + info->index.str = shdr->sh_link; + info->strtab = (char *)info->hdr + info->sechdrs[info->index.str].sh_offset; + /* * The ".gnu.linkonce.this_module" ELF section is special. It is * what modpost uses to refer to __this_module and let's use rely @@ -1802,7 +1831,8 @@ static int elf_validity_check(struct load_info *info) * size */ if (num_mod_secs != 1) { - pr_err("Only one .gnu.linkonce.this_module section must exist.\n"); + pr_err("module %s: Only one .gnu.linkonce.this_module section must exist.\n", + info->name ?: "(missing .modinfo section or name field)"); goto no_exec; } @@ -1813,17 +1843,20 @@ static int elf_validity_check(struct load_info *info) * pedantic about it. */ if (shdr->sh_type == SHT_NOBITS) { - pr_err(".gnu.linkonce.this_module section must have a size set\n"); + pr_err("module %s: .gnu.linkonce.this_module section must have a size set\n", + info->name ?: "(missing .modinfo section or name field)"); goto no_exec; } if (!(shdr->sh_flags & SHF_ALLOC)) { - pr_err(".gnu.linkonce.this_module must occupy memory during process execution\n"); + pr_err("module %s: .gnu.linkonce.this_module must occupy memory during process execution\n", + info->name ?: "(missing .modinfo section or name field)"); goto no_exec; } if (shdr->sh_size != sizeof(struct module)) { - pr_err(".gnu.linkonce.this_module section size must match the kernel's built struct module size at run time\n"); + pr_err("module %s: .gnu.linkonce.this_module section size must match the kernel's built struct module size at run time\n", + info->name ?: "(missing .modinfo section or name field)"); goto no_exec; } @@ -1832,6 +1865,13 @@ static int elf_validity_check(struct load_info *info) /* This is temporary: point mod into copy of data. */ info->mod = (void *)info->hdr + shdr->sh_offset; + /* + * If we didn't load the .modinfo 'name' field earlier, fall back to + * on-disk struct mod 'name' field. + */ + if (!info->name) + info->name = info->mod->name; + return 0; no_exec: @@ -1954,37 +1994,6 @@ static int rewrite_section_headers(struct load_info *info, int flags) */ static int setup_load_info(struct load_info *info, int flags) { - unsigned int i; - - /* Try to find a name early so we can log errors with a module name */ - info->index.info = find_sec(info, ".modinfo"); - if (info->index.info) - info->name = get_modinfo(info, "name"); - - /* Find internal symbols and strings. */ - for (i = 1; i < info->hdr->e_shnum; i++) { - 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; - break; - } - } - - if (info->index.sym == 0) { - pr_warn("%s: module has no symbols (stripped?)\n", - info->name ?: "(missing .modinfo section or name field)"); - return -ENOEXEC; - } - - /* - * If we didn't load the .modinfo 'name' field earlier, fall back to - * on-disk struct mod 'name' field. - */ - if (!info->name) - info->name = info->mod->name; - if (flags & MODULE_INIT_IGNORE_MODVERSIONS) info->index.vers = 0; /* Pretend no __versions section! */ else