Change our ELF binary branding to something more acceptable to the Binutils

maintainers.

After we established our branding method of writing upto 8 characters of
the OS name into the ELF header in the padding; the Binutils maintainers
and/or SCO (as USL) decided that instead the ELF header should grow two new
fields -- EI_OSABI and EI_ABIVERSION.  Each of these are an 8-bit unsigned
integer.  SCO has assigned official values for the EI_OSABI field.  In
addition to this, the Binutils maintainers and NetBSD decided that a better
ELF branding method was to include ABI information in a ".note" ELF
section.

With this set of changes, we will now create ELF binaries branded using
both "official" methods.  Due to the complexity of adding a section to a
binary, binaries branded with ``brandelf'' will only brand using the
EI_OSABI method.  Also due to the complexity of pulling a section out of an
ELF file vs. poking around in the ELF header, our image activator only
looks at the EI_OSABI header field.

Note that a new kernel can still properly load old binaries except for
Linux static binaries branded in our old method.

  *
  * For a short period of time, ``ld'' will also brand ELF binaries
  * using our old method.  This is so people can still use kernel.old
  * with a new world.  This support will be removed before 5.0-RELEASE,
  * and may not last anywhere upto the actual release.  My expiration
  * time for this is about 6mo.
  *

7 files changed, 64 insertions, 49 deletions

diff --git a/sys/alpha/linux/linux_sysvec.c b/sys/alpha/linux/linux_sysvec.c
index 39f3000..a92cd8ad 100644
--- a/sys/alpha/linux/linux_sysvec.c
+++ b/sys/alpha/linux/linux_sysvec.c
@@ -439,14 +439,14 @@ struct sysentvec elf_linux_sysvec = {
 };
 
 static Elf32_Brandinfo linux_brand = {
-					"Linux",
+					ELFOSABI_LINUX,
 					"/compat/linux",
 					"/lib/ld-linux.so.1",
 					&elf_linux_sysvec
 				 };
 
 static Elf32_Brandinfo linux_glibc2brand = {
-					"Linux",
+					ELFOSABI_LINUX,
 					"/compat/linux",
 					"/lib/ld-linux.so.2",
 					&elf_linux_sysvec
diff --git a/sys/compat/svr4/svr4_sysvec.c b/sys/compat/svr4/svr4_sysvec.c
index b470157..c66e61b 100644
--- a/sys/compat/svr4/svr4_sysvec.c
+++ b/sys/compat/svr4/svr4_sysvec.c
@@ -155,7 +155,7 @@ int bsd_to_svr4_errno[ELAST+1] = {
 };
 
 
-static int 	svr4_fixup(long **stack_base, struct image_params *imgp);
+static int 	svr4_fixup(register_t **stack_base, struct image_params *imgp);
 
 extern struct sysent svr4_sysent[];
 #undef szsigcode
@@ -183,8 +183,8 @@ struct sysentvec svr4_sysvec = {
 };
 
 Elf32_Brandinfo svr4_brand = {
-  "SVR4",
-  "/compat/svr4",
+  ELFOSABI_SOLARIS,		/* XXX  Or should we use ELFOSABI_SYSV here?  */
+  svr4_emul_path,
   "/lib/libc.so.1",
   &svr4_sysvec
 };
@@ -192,10 +192,10 @@ Elf32_Brandinfo svr4_brand = {
 const char      svr4_emul_path[] = "/compat/svr4";
 
 static int
-svr4_fixup(long **stack_base, struct image_params *imgp)
+svr4_fixup(register_t **stack_base, struct image_params *imgp)
 {
 	Elf32_Auxargs *args = (Elf32_Auxargs *)imgp->auxargs;
-	long *pos;
+	register_t *pos;
              
 	pos = *stack_base + (imgp->argc + imgp->envc + 2);  
     
diff --git a/sys/i386/linux/linux_sysvec.c b/sys/i386/linux/linux_sysvec.c
index 39f3000..a92cd8ad 100644
--- a/sys/i386/linux/linux_sysvec.c
+++ b/sys/i386/linux/linux_sysvec.c
@@ -439,14 +439,14 @@ struct sysentvec elf_linux_sysvec = {
 };
 
 static Elf32_Brandinfo linux_brand = {
-					"Linux",
+					ELFOSABI_LINUX,
 					"/compat/linux",
 					"/lib/ld-linux.so.1",
 					&elf_linux_sysvec
 				 };
 
 static Elf32_Brandinfo linux_glibc2brand = {
-					"Linux",
+					ELFOSABI_LINUX,
 					"/compat/linux",
 					"/lib/ld-linux.so.2",
 					&elf_linux_sysvec
diff --git a/sys/kern/imgact_elf.c b/sys/kern/imgact_elf.c
index 6a0e0ef..8fe3362 100644
--- a/sys/kern/imgact_elf.c
+++ b/sys/kern/imgact_elf.c
@@ -65,6 +65,8 @@
 #include <machine/elf.h>
 #include <machine/md_var.h>
 
+#define OLD_EI_BRAND	8
+
 __ElfType(Brandinfo);
 __ElfType(Auxargs);
 
@@ -82,12 +84,6 @@ static int exec_elf_imgact __P((struct image_params *imgp));
 static int elf_trace = 0;
 SYSCTL_INT(_debug, OID_AUTO, elf_trace, CTLFLAG_RW, &elf_trace, 0, "");
 
-/*
- * XXX Maximum length of an ELF brand (sysctl wants a statically-allocated
- * buffer).
- */
-#define	MAXBRANDLEN	16
-
 static struct sysentvec elf_freebsd_sysvec = {
         SYS_MAXSYSCALL,
         sysent,
@@ -107,7 +103,7 @@ static struct sysentvec elf_freebsd_sysvec = {
 };
 
 static Elf_Brandinfo freebsd_brand_info = {
-						"FreeBSD",
+						ELFOSABI_FREEBSD,
 						"",
 						"/usr/libexec/ld-elf.so.1",
 						&elf_freebsd_sysvec
@@ -412,9 +408,9 @@ fail:
 	return error;
 }
 
-static char fallback_elf_brand[MAXBRANDLEN+1] = { "none" };
-SYSCTL_STRING(_kern, OID_AUTO, fallback_elf_brand, CTLFLAG_RW,
-		fallback_elf_brand, sizeof(fallback_elf_brand),
+static int fallback_elf_brand = ELFOSABI_FREEBSD;
+SYSCTL_INT(_kern, OID_AUTO, fallback_elf_brand, CTLFLAG_RW,
+		&fallback_elf_brand, ELFOSABI_FREEBSD,
 		"ELF brand of last resort");
 
 static int
@@ -431,7 +427,6 @@ exec_elf_imgact(struct image_params *imgp)
 	int error, i;
 	const char *interp = NULL;
 	Elf_Brandinfo *brand_info;
-	const char *brand;
 	char path[MAXPATHLEN];
 
 	/*
@@ -526,14 +521,23 @@ exec_elf_imgact(struct image_params *imgp)
 
 	imgp->entry_addr = entry;
 
-	/* If the executable has a brand, search for it in the brand list. */
 	brand_info = NULL;
-	brand = (const char *)&hdr->e_ident[EI_BRAND];
-	if (brand[0] != '\0') {
+
+	/* XXX  For now we look for the magic "FreeBSD" that we used to put
+	 * into the ELF header at the EI_ABIVERSION location.  If found use
+	 * that information rather than figuring out the ABI from proper
+	 * branding.  This should be removed for 5.0-RELEASE. The Linux caes
+	 * can be figured out from the `interp_path' field.
+	 */
+	if (strcmp("FreeBSD", (const char *)&hdr->e_ident[OLD_EI_BRAND]) == 0)
+		brand_info = &freebsd_brand_info;
+
+	/* If the executable has a brand, search for it in the brand list. */
+	if (brand_info == NULL) {
 		for (i = 0;  i < MAX_BRANDS;  i++) {
 			Elf_Brandinfo *bi = elf_brand_list[i];
 
-			if (bi != NULL && strcmp(brand, bi->brand) == 0) {
+			if (bi != NULL && hdr->e_ident[EI_OSABI] == bi->brand) {
 				brand_info = bi;
 				break;
 			}
@@ -554,31 +558,24 @@ exec_elf_imgact(struct image_params *imgp)
 	}
 
 	/* Lacking a recognized interpreter, try the default brand */
-	if (brand_info == NULL && fallback_elf_brand[0] != '\0') {
+	if (brand_info == NULL) {
 		for (i = 0; i < MAX_BRANDS; i++) {
 			Elf_Brandinfo *bi = elf_brand_list[i];
 
-			if (bi != NULL
-			    && strcmp(fallback_elf_brand, bi->brand) == 0) {
+			if (bi != NULL && fallback_elf_brand == bi->brand) {
 				brand_info = bi;
 				break;
 			}
 		}
 	}
 
-#ifdef __alpha__
-	/* XXX - Assume FreeBSD on the alpha. */
+	/* XXX - Assume FreeBSD after the branding method change. */
 	if (brand_info == NULL)
 		brand_info = &freebsd_brand_info;
-#endif
 
 	if (brand_info == NULL) {
-		if (brand[0] == 0)
-			uprintf("ELF binary type not known."
-			    "  Use \"brandelf\" to brand it.\n");
-		else
-			uprintf("ELF binary type \"%.*s\" not known.\n",
-			    EI_NIDENT - EI_BRAND, brand);
+		uprintf("ELF binary type \"%u\" not known.\n",
+		    hdr->e_ident[EI_OSABI]);
 		error = ENOEXEC;
 		goto fail;
 	}
@@ -932,9 +929,9 @@ elf_puthdr(struct proc *p, void *dst, size_t *off, const prstatus_t *status,
 		ehdr->e_ident[EI_CLASS] = ELF_CLASS;
 		ehdr->e_ident[EI_DATA] = ELF_DATA;
 		ehdr->e_ident[EI_VERSION] = EV_CURRENT;
+		ehdr->e_ident[EI_OSABI] = ELFOSABI_FREEBSD;
+		ehdr->e_ident[EI_ABIVERSION] = 0;
 		ehdr->e_ident[EI_PAD] = 0;
-		strncpy(ehdr->e_ident + EI_BRAND, "FreeBSD",
-		    EI_NIDENT - EI_BRAND);
 		ehdr->e_type = ET_CORE;
 		ehdr->e_machine = ELF_ARCH;
 		ehdr->e_version = EV_CURRENT;
diff --git a/sys/svr4/svr4_sysvec.c b/sys/svr4/svr4_sysvec.c
index b470157..c66e61b 100644
--- a/sys/svr4/svr4_sysvec.c
+++ b/sys/svr4/svr4_sysvec.c
@@ -155,7 +155,7 @@ int bsd_to_svr4_errno[ELAST+1] = {
 };
 
 
-static int 	svr4_fixup(long **stack_base, struct image_params *imgp);
+static int 	svr4_fixup(register_t **stack_base, struct image_params *imgp);
 
 extern struct sysent svr4_sysent[];
 #undef szsigcode
@@ -183,8 +183,8 @@ struct sysentvec svr4_sysvec = {
 };
 
 Elf32_Brandinfo svr4_brand = {
-  "SVR4",
-  "/compat/svr4",
+  ELFOSABI_SOLARIS,		/* XXX  Or should we use ELFOSABI_SYSV here?  */
+  svr4_emul_path,
   "/lib/libc.so.1",
   &svr4_sysvec
 };
@@ -192,10 +192,10 @@ Elf32_Brandinfo svr4_brand = {
 const char      svr4_emul_path[] = "/compat/svr4";
 
 static int
-svr4_fixup(long **stack_base, struct image_params *imgp)
+svr4_fixup(register_t **stack_base, struct image_params *imgp)
 {
 	Elf32_Auxargs *args = (Elf32_Auxargs *)imgp->auxargs;
-	long *pos;
+	register_t *pos;
              
 	pos = *stack_base + (imgp->argc + imgp->envc + 2);  
     
diff --git a/sys/sys/elf_common.h b/sys/sys/elf_common.h
index 207050d..f63f384 100644
--- a/sys/sys/elf_common.h
+++ b/sys/sys/elf_common.h
@@ -48,7 +48,8 @@ typedef struct {
 	u_int32_t	n_type;		/* Type of this note. */
 } Elf_Note;
 
-/* Indexes into the e_ident array. */
+/* Indexes into the e_ident array.  Keep synced with 
+   http://www.sco.com/developer/gabi/ch4.eheader.html */
 #define EI_MAG0		0	/* Magic number, byte 0. */
 #define EI_MAG1		1	/* Magic number, byte 1. */
 #define EI_MAG2		2	/* Magic number, byte 2. */
@@ -56,8 +57,10 @@ typedef struct {
 #define EI_CLASS	4	/* Class of machine. */
 #define EI_DATA		5	/* Data format. */
 #define EI_VERSION	6	/* ELF format version. */
-#define EI_PAD		7	/* Start of padding (per SVR4 ABI). */
-#define EI_BRAND	8	/* Start of architecture identification. */
+#define EI_OSABI	7	/* Operating system / ABI identification */
+#define EI_ABIVERSION	8	/* ABI version */
+#define OLD_EI_BRAND	8	/* Start of architecture identification. */
+#define EI_PAD		9	/* Start of padding (per SVR4 ABI). */
 #define EI_NIDENT	16	/* Size of e_ident array. */
 
 /* Values for the magic number bytes. */
@@ -80,6 +83,21 @@ typedef struct {
 #define ELFDATA2LSB	1	/* 2's complement little-endian. */
 #define ELFDATA2MSB	2	/* 2's complement big-endian. */
 
+/* Values for e_ident[EI_OSABI]. */
+#define ELFOSABI_SYSV		0	/* UNIX System V ABI */
+#define ELFOSABI_HPUX		1	/* HP-UX operating system */
+#define ELFOSABI_NETBSD		2	/* NetBSD */
+#define ELFOSABI_LINUX		3	/* GNU/Linux */
+#define ELFOSABI_HURD		4	/* GNU/Hurd */
+#define ELFOSABI_86OPEN		5	/* 86Open common IA32 ABI */
+#define ELFOSABI_SOLARIS	6	/* Solaris */
+#define ELFOSABI_MONTEREY	7	/* Monterey */
+#define ELFOSABI_IRIX		8	/* IRIX */
+#define ELFOSABI_FREEBSD	9	/* FreeBSD */
+#define ELFOSABI_TRU64		10	/* TRU64 UNIX */
+#define ELFOSABI_ARM		97	/* ARM */
+#define ELFOSABI_STANDALONE	255	/* Standalone (embedded) application */
+
 /* e_ident */
 #define IS_ELF(ehdr)	((ehdr).e_ident[EI_MAG0] == ELFMAG0 && \
 			 (ehdr).e_ident[EI_MAG1] == ELFMAG1 && \
diff --git a/sys/sys/imgact_elf.h b/sys/sys/imgact_elf.h
index 065d5b5..b781552 100644
--- a/sys/sys/imgact_elf.h
+++ b/sys/sys/imgact_elf.h
@@ -56,9 +56,9 @@ typedef struct {
 } Elf32_Auxargs;
 
 typedef struct {
-	char *brand;
-	char *emul_path;
-	char *interp_path;
+	int brand;
+	const char *emul_path;
+	const char *interp_path;
         struct sysentvec *sysvec;
 } Elf32_Brandinfo;