Re: consolidate ELF header checks

[Guillem Jover <guillem@hadrons.org>]

Hi,

On Fri, Feb 04, 2005 at 10:25:03PM +0000, Marco Gerards wrote:
> Guillem Jover <guillem@hadrons.org> writes:
> > This patch merges common ELF header checks. Please test this on PPC
> > as I've only tested on x86.
> 
> I've done that.  I could load linux using this patch after a small
> change.

Thanks! :)

> As far as I am concerned there are no other issues with this patch.
> If someone else has problems with this patch, please tell me.
> Otherwise I will commit it soon, if Guillem can fix these issues... :)

I've fixed the error messages, the missing & and the unused size
variable warnings.

regards,
guillem


2005-02-05  Guillem Jover  <guillem@hadrons.org>

	* include/grub/dl.h (grub_dl_check_header): New prototype.
	(grub_arch_dl_check_header): Change return type to grub_err_t and
	remove size parameter. Fix all callers.
	* kern/dl.c (grub_dl_check_header): New function.
	(grub_dl_load_core): Use grub_dl_check_header instead of
	grub_arch_dl_check_header. Check ELF type. Check sections to be
	inside the core.
	* kern/i386/dl.c (grub_arch_dl_check_header): Remove arch
	independent ELF header checks.
	* kern/powerpc/dl.c (grub_arch_dl_check_header): Likewise.
	* loader/i386/pc/multiboot.c (grub_rescue_cmd_multiboot): Use
	grub_dl_check_header instead of explicit checks. Check for ELF type.
	* loader/powerpc/ieee1275/linux.c (grub_rescue_cmd_linux): Use
	grub_dl_check_header instead of explicit checks. Remove arch specific
	ELF header checks.

diff -Naupr -x CVS grub2-cvs/include/grub/dl.h grub2.dl/include/grub/dl.h
--- grub2-cvs/include/grub/dl.h	2005-02-01 04:34:12.000000000 +0100
+++ grub2.dl/include/grub/dl.h	2005-02-01 04:03:26.000000000 +0100
@@ -70,6 +70,7 @@ struct grub_dl
 };
 typedef struct grub_dl *grub_dl_t;
 
+grub_err_t EXPORT_FUNC(grub_dl_check_header) (void *ehdr, grub_size_t size);
 grub_dl_t EXPORT_FUNC(grub_dl_load_file) (const char *filename);
 grub_dl_t EXPORT_FUNC(grub_dl_load) (const char *name);
 grub_dl_t grub_dl_load_core (void *addr, grub_size_t size);
@@ -84,7 +85,7 @@ grub_err_t EXPORT_FUNC(grub_dl_register_
 					    grub_dl_t mod);
 void *EXPORT_FUNC(grub_dl_resolve_symbol) (const char *name);
 
-int grub_arch_dl_check_header (void *ehdr, grub_size_t size);
+grub_err_t grub_arch_dl_check_header (void *ehdr);
 grub_err_t grub_arch_dl_relocate_symbols (grub_dl_t mod, void *ehdr);
 
 #endif /* ! GRUB_DL_H */
diff -Naupr -x CVS grub2-cvs/kern/dl.c grub2.dl/kern/dl.c
--- grub2-cvs/kern/dl.c	2005-02-01 04:34:13.000000000 +0100
+++ grub2.dl/kern/dl.c	2005-02-01 04:05:45.000000000 +0100
@@ -238,6 +238,29 @@
   return 0;
 }
 
+/* Check if EHDR is a valid ELF header.  */
+grub_err_t
+grub_dl_check_header (void *ehdr, grub_size_t size)
+{
+  Elf_Ehdr *e = ehdr;
+
+  /* Check the header size.  */
+  if (size < sizeof (Elf_Ehdr))
+    return grub_error (GRUB_ERR_BAD_OS, "ELF header smaller than expected");
+
+  /* Check the magic numbers.  */
+  if (grub_arch_dl_check_header (ehdr)
+      || e->e_ident[EI_MAG0] != ELFMAG0
+      || e->e_ident[EI_MAG1] != ELFMAG1
+      || e->e_ident[EI_MAG2] != ELFMAG2
+      || e->e_ident[EI_MAG3] != ELFMAG3
+      || e->e_ident[EI_VERSION] != EV_CURRENT
+      || e->e_version != EV_CURRENT)
+    return grub_error (GRUB_ERR_BAD_OS, "Invalid arch independent ELF magic");
+
+  return GRUB_ERR_NONE;
+}
+
 /* Load all segments from memory specified by E.  */
 static grub_err_t
 grub_dl_load_segments (grub_dl_t mod, const Elf_Ehdr *e)
@@ -497,12 +520,25 @@ grub_dl_load_core (void *addr, grub_size
   grub_dl_t mod;
   
   e = addr;
-  if (! grub_arch_dl_check_header (e, size))
+  if (grub_dl_check_header (e, size))
     {
       grub_error (GRUB_ERR_BAD_MODULE, "invalid ELF header");
       return 0;
     }
   
+  if (e->e_type != ET_REL)
+    {
+      grub_error (GRUB_ERR_BAD_MODULE, "Invalid ELF file type\n");
+      return 0;
+    }
+
+  /* Make sure that every section is within the core.  */
+  if (size < e->e_shoff + e->e_shentsize * e->e_shnum)
+    {
+      grub_error (GRUB_ERR_BAD_OS, "ELF sections outside core");
+      return 0;
+    }
+
   mod = (grub_dl_t) grub_malloc (sizeof (*mod));
   if (! mod)
     return 0;
diff -Naupr -x CVS grub2-cvs/kern/i386/dl.c grub2.dl/kern/i386/dl.c
--- grub2-cvs/kern/i386/dl.c	2005-02-01 04:34:13.000000000 +0100
+++ grub2.dl/kern/i386/dl.c	2005-02-01 04:03:26.000000000 +0100
@@ -24,32 +24,18 @@
 #include <grub/err.h>
 
 /* Check if EHDR is a valid ELF header.  */
-int
-grub_arch_dl_check_header (void *ehdr, grub_size_t size)
+grub_err_t
+grub_arch_dl_check_header (void *ehdr)
 {
   Elf32_Ehdr *e = ehdr;
 
-  /* Check the header size.  */
-  if (size < sizeof (Elf32_Ehdr))
-    return 0;
-
   /* Check the magic numbers.  */
-  if (e->e_ident[EI_MAG0] != ELFMAG0
-      || e->e_ident[EI_MAG1] != ELFMAG1
-      || e->e_ident[EI_MAG2] != ELFMAG2
-      || e->e_ident[EI_MAG3] != ELFMAG3
-      || e->e_version != EV_CURRENT
-      || e->e_ident[EI_CLASS] != ELFCLASS32
+  if (e->e_ident[EI_CLASS] != ELFCLASS32
       || e->e_ident[EI_DATA] != ELFDATA2LSB
-      || e->e_machine != EM_386
-      || e->e_type != ET_REL)
-    return 0;
-
-  /* Make sure that every section is within the core.  */
-  if (size < e->e_shoff + e->e_shentsize * e->e_shnum)
-    return 0;
+      || e->e_machine != EM_386)
+    return grub_error (GRUB_ERR_BAD_OS, "Invalid arch specific ELF magic");
 
-  return 1;
+  return GRUB_ERR_NONE;
 }
 
 /* Relocate symbols.  */
diff -Naupr -x CVS grub2-cvs/kern/powerpc/dl.c grub2.dl/kern/powerpc/dl.c
--- grub2-cvs/kern/powerpc/dl.c	2005-02-01 04:34:13.000000000 +0100
+++ grub2.dl/kern/powerpc/dl.c	2005-02-01 04:03:26.000000000 +0100
@@ -24,32 +24,18 @@
 #include <grub/err.h>
 
 /* Check if EHDR is a valid ELF header.  */
-int
-grub_arch_dl_check_header (void *ehdr, grub_size_t size)
+grub_err_t
+grub_arch_dl_check_header (void *ehdr)
 {
   Elf32_Ehdr *e = ehdr;
 
-  /* Check the header size.  */
-  if (size < sizeof (Elf32_Ehdr))
-    return 0;
-
   /* Check the magic numbers.  */
-  if (!((e->e_ident[EI_MAG0] == ELFMAG0) 
-	&& (e->e_ident[EI_MAG1] == ELFMAG1)
-	&& (e->e_ident[EI_MAG2] == ELFMAG2) 
-	&& (e->e_ident[EI_MAG3] == ELFMAG3)
-	&& (e->e_ident[EI_CLASS] == ELFCLASS32) 
-	&& (e->e_ident[EI_DATA] == ELFDATA2MSB)
-	&& (e->e_ident[EI_VERSION] == EV_CURRENT) 
-	&& (e->e_type == ET_REL) && (e->e_machine == EM_PPC) 
-	&& (e->e_version == EV_CURRENT)))
-    return 0;
-  
-  /* Make sure that every section is within the core.  */
-  if (size < e->e_shoff + e->e_shentsize * e->e_shnum)
-    return 0;
+  if (e->e_ident[EI_CLASS] != ELFCLASS32
+      || e->e_ident[EI_DATA] != ELFDATA2MSB
+      || e->e_machine != EM_PPC)
+    return grub_error (GRUB_ERR_BAD_OS, "Invalid arch specific ELF magic");
 
-  return 1;
+  return GRUB_ERR_NONE;
 }
 
 
diff -Naupr -x CVS grub2-cvs/loader/i386/pc/multiboot.c grub2.dl/loader/i386/pc/multiboot.c
--- grub2-cvs/loader/i386/pc/multiboot.c	2005-02-01 04:34:13.000000000 +0100
+++ grub2.dl/loader/i386/pc/multiboot.c	2005-02-01 04:35:25.000000000 +0100
@@ -140,20 +140,18 @@ grub_rescue_cmd_multiboot (int argc, cha
 
   ehdr = (Elf32_Ehdr *) buffer;
 
-  if (!((ehdr->e_ident[EI_MAG0] == ELFMAG0) 
-	&& (ehdr->e_ident[EI_MAG1] == ELFMAG1)
-	&& (ehdr->e_ident[EI_MAG2] == ELFMAG2) 
-	&& (ehdr->e_ident[EI_MAG3] == ELFMAG3)
-	&& (ehdr->e_ident[EI_CLASS] == ELFCLASS32) 
-	&& (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
-	&& (ehdr->e_ident[EI_VERSION] == EV_CURRENT) 
-	&& (ehdr->e_type == ET_EXEC) && (ehdr->e_machine == EM_386) 
-	&& (ehdr->e_version == EV_CURRENT)))
+  if (grub_dl_check_header (ehdr, sizeof(*ehdr)))
     {
       grub_error (GRUB_ERR_UNKNOWN_OS, "No valid ELF header found");
       goto fail;
     }
 
+  if (ehdr->e_type != ET_EXEC)
+    {
+      grub_error (GRUB_ERR_UNKNOWN_OS, "Invalid ELF file type\n");
+      goto fail;
+    }
+
   /* FIXME: Should we support program headers at strange locations?  */
   if (ehdr->e_phoff + ehdr->e_phnum * ehdr->e_phentsize > GRUB_MB_SEARCH)
     {
diff -Naupr -x CVS grub2-cvs/loader/powerpc/ieee1275/linux.c grub2.dl/loader/powerpc/ieee1275/linux.c
--- grub2-cvs/loader/powerpc/ieee1275/linux.c	2005-02-01 04:34:13.000000000 +0100
+++ grub2.dl/loader/powerpc/ieee1275/linux.c	2005-02-01 04:03:26.000000000 +0100
@@ -124,15 +124,7 @@ grub_rescue_cmd_linux (int argc, char *a
       goto fail;
     }
   
-  if (!((ehdr.e_ident[EI_MAG0] == ELFMAG0) 
-	&& (ehdr.e_ident[EI_MAG1] == ELFMAG1)
-	&& (ehdr.e_ident[EI_MAG2] == ELFMAG2) 
-	&& (ehdr.e_ident[EI_MAG3] == ELFMAG3)
-	&& (ehdr.e_ident[EI_CLASS] == ELFCLASS32) 
-	&& (ehdr.e_ident[EI_DATA] == ELFDATA2MSB)
-	&& (ehdr.e_ident[EI_VERSION] == EV_CURRENT) 
-	&& (ehdr.e_type == ET_EXEC) && (ehdr.e_machine == EM_PPC) 
-	&& (ehdr.e_version == EV_CURRENT)))
+  if (grub_dl_check_header (&ehdr, sizeof(ehdr)))
     {
       grub_error (GRUB_ERR_UNKNOWN_OS, "No valid ELF header found");
       goto fail;
@@ -145,20 +137,6 @@ grub_rescue_cmd_linux (int argc, char *a
       goto fail;
     }
 
-  if (ehdr.e_machine != EM_PPC)
-    {
-      grub_error (GRUB_ERR_UNKNOWN_OS,
-		  "This ELF file is not for the PPC32\n");
-      goto fail;
-    }
-  
-  if (ehdr.e_version != EV_CURRENT)
-    {
-      grub_error (GRUB_ERR_UNKNOWN_OS,
-		  "Invalid ELF version\n");
-      goto fail;
-    }
-
   /* Read the sections.  */
   entry = ehdr.e_entry;
   if (entry == 0xc0000000)
diff -Naupr -x CVS grub2-cvs/util/grub-emu.c grub2.dl/util/grub-emu.c
--- grub2-cvs/util/grub-emu.c	2005-02-01 04:34:13.000000000 +0100
+++ grub2.dl/util/grub-emu.c	2005-02-01 04:03:26.000000000 +0100
@@ -51,11 +51,10 @@ grub_arch_modules_addr (void)
   return 0;
 }
 
-int
-grub_arch_dl_check_header (void *ehdr, grub_size_t size)
+grub_err_t
+grub_arch_dl_check_header (void *ehdr)
 {
   (void) ehdr;
-  (void) size;
 
   return GRUB_ERR_BAD_MODULE;
 }