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: Rusty Russell <rusty@rustcorp.com.au>

diff --git a/kernel/module.c b/kernel/module.c
index 19ddcb0..d8faf35 100644 (file)
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -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");
-               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;
+       err = check_modinfo(mod, sechdrs, infoindex, versindex);
+       if (err)
                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);