From 2f3238aebedb243804f58d62d57244edec4149b2 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Mon, 22 Oct 2012 18:09:41 +1030 Subject: [PATCH] module: add flags arg to sys_finit_module() Thanks to Michael Kerrisk for keeping us honest. These flags are actually useful for eliminating the only case where kmod has to mangle a module's internals: for overriding module versioning. Signed-off-by: Rusty Russell Acked-by: Lucas De Marchi Acked-by: Kees Cook --- include/linux/syscalls.h | 2 +- include/uapi/linux/module.h | 8 ++++++++ kernel/module.c | 40 ++++++++++++++++++++++++------------- 3 files changed, 35 insertions(+), 15 deletions(-) create mode 100644 include/uapi/linux/module.h diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index 32bc035bcd68..8cf7b508cb50 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -868,5 +868,5 @@ asmlinkage long sys_process_vm_writev(pid_t pid, asmlinkage long sys_kcmp(pid_t pid1, pid_t pid2, int type, unsigned long idx1, unsigned long idx2); -asmlinkage long sys_finit_module(int fd, const char __user *uargs); +asmlinkage long sys_finit_module(int fd, const char __user *uargs, int flags); #endif diff --git a/include/uapi/linux/module.h b/include/uapi/linux/module.h new file mode 100644 index 000000000000..38da4258b12f --- /dev/null +++ b/include/uapi/linux/module.h @@ -0,0 +1,8 @@ +#ifndef _UAPI_LINUX_MODULE_H +#define _UAPI_LINUX_MODULE_H + +/* Flags for sys_finit_module: */ +#define MODULE_INIT_IGNORE_MODVERSIONS 1 +#define MODULE_INIT_IGNORE_VERMAGIC 2 + +#endif /* _UAPI_LINUX_MODULE_H */ diff --git a/kernel/module.c b/kernel/module.c index 6d2c4e4ca1f5..1395ca382fb5 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -60,6 +60,7 @@ #include #include #include +#include #include "module-internal.h" #define CREATE_TRACE_POINTS @@ -2553,7 +2554,7 @@ static void free_copy(struct load_info *info) vfree(info->hdr); } -static int rewrite_section_headers(struct load_info *info) +static int rewrite_section_headers(struct load_info *info, int flags) { unsigned int i; @@ -2581,7 +2582,10 @@ static int rewrite_section_headers(struct load_info *info) } /* Track but don't keep modinfo and version sections. */ - info->index.vers = find_sec(info, "__versions"); + if (flags & MODULE_INIT_IGNORE_MODVERSIONS) + info->index.vers = 0; /* Pretend no __versions section! */ + else + info->index.vers = find_sec(info, "__versions"); info->index.info = find_sec(info, ".modinfo"); info->sechdrs[info->index.info].sh_flags &= ~(unsigned long)SHF_ALLOC; info->sechdrs[info->index.vers].sh_flags &= ~(unsigned long)SHF_ALLOC; @@ -2596,7 +2600,7 @@ static int rewrite_section_headers(struct load_info *info) * Return the temporary module pointer (we'll replace it with the final * one when we move the module sections around). */ -static struct module *setup_load_info(struct load_info *info) +static struct module *setup_load_info(struct load_info *info, int flags) { unsigned int i; int err; @@ -2607,7 +2611,7 @@ static struct module *setup_load_info(struct load_info *info) info->secstrings = (void *)info->hdr + info->sechdrs[info->hdr->e_shstrndx].sh_offset; - err = rewrite_section_headers(info); + err = rewrite_section_headers(info, flags); if (err) return ERR_PTR(err); @@ -2645,11 +2649,14 @@ static struct module *setup_load_info(struct load_info *info) return mod; } -static int check_modinfo(struct module *mod, struct load_info *info) +static int check_modinfo(struct module *mod, struct load_info *info, int flags) { const char *modmagic = get_modinfo(info, "vermagic"); int err; + if (flags & MODULE_INIT_IGNORE_VERMAGIC) + modmagic = NULL; + /* This is allowed: modprobe --force will invalidate it. */ if (!modmagic) { err = try_to_force_load(mod, "bad vermagic"); @@ -2885,18 +2892,18 @@ int __weak module_frob_arch_sections(Elf_Ehdr *hdr, return 0; } -static struct module *layout_and_allocate(struct load_info *info) +static struct module *layout_and_allocate(struct load_info *info, int flags) { /* Module within temporary copy. */ struct module *mod; Elf_Shdr *pcpusec; int err; - mod = setup_load_info(info); + mod = setup_load_info(info, flags); if (IS_ERR(mod)) return mod; - err = check_modinfo(mod, info); + err = check_modinfo(mod, info, flags); if (err) return ERR_PTR(err); @@ -3078,7 +3085,8 @@ static int may_init_module(void) /* Allocate and load the module: note that size of section 0 is always zero, and we rely on this for optional sections. */ -static int load_module(struct load_info *info, const char __user *uargs) +static int load_module(struct load_info *info, const char __user *uargs, + int flags) { struct module *mod, *old; long err; @@ -3092,7 +3100,7 @@ static int load_module(struct load_info *info, const char __user *uargs) goto free_copy; /* Figure out module layout, and allocate all the memory. */ - mod = layout_and_allocate(info); + mod = layout_and_allocate(info, flags); if (IS_ERR(mod)) { err = PTR_ERR(mod); goto free_copy; @@ -3241,10 +3249,10 @@ SYSCALL_DEFINE3(init_module, void __user *, umod, if (err) return err; - return load_module(&info, uargs); + return load_module(&info, uargs, 0); } -SYSCALL_DEFINE2(finit_module, int, fd, const char __user *, uargs) +SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags) { int err; struct load_info info = { }; @@ -3253,13 +3261,17 @@ SYSCALL_DEFINE2(finit_module, int, fd, const char __user *, uargs) if (err) return err; - pr_debug("finit_module: fd=%d, uargs=%p\n", fd, uargs); + pr_debug("finit_module: fd=%d, uargs=%p, flags=%i\n", fd, uargs, flags); + + if (flags & ~(MODULE_INIT_IGNORE_MODVERSIONS + |MODULE_INIT_IGNORE_VERMAGIC)) + return -EINVAL; err = copy_module_from_fd(fd, &info); if (err) return err; - return load_module(&info, uargs); + return load_module(&info, uargs, flags); } static inline int within(unsigned long addr, void *start, unsigned long size)