binfmt_elf_fdpic: support 64-bit systems

The binfmt_flat_fdpic code has a number of 32-bit specific data
structures associated with it. Extend it to be able to support and
be used on 64-bit systems as well.

The new code defines a number of key 64-bit variants of the core
elf-fdpic data structures - along side the existing 32-bit sized ones.
A common set of generic named structures are defined to be either
the 32-bit or 64-bit ones as required at compile time. This is a
similar technique to that used in the ELF binfmt loader.

For example:

  elf_fdpic_loadseg is either elf32_fdpic_loadseg or elf64_fdpic_loadseg
  elf_fdpic_loadmap is either elf32_fdpic_loadmap or elf64_fdpic_loadmap

the choice based on ELFCLASS32 or ELFCLASS64.
Signed-off-by: Greg Ungerer <gerg@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230711130754.481209-2-gerg@kernel.orgSigned-off-by: Palmer Dabbelt <palmer@rivosinc.com>

fs/binfmt_elf_fdpic.c

@@ -138,7 +138,7 @@ static int is_constdisp(struct elfhdr *hdr)
 static int elf_fdpic_fetch_phdrs(struct elf_fdpic_params *params,
 				 struct file *file)
 {
-	struct elf32_phdr *phdr;
+	struct elf_phdr *phdr;
 	unsigned long size;
 	int retval, loop;
 	loff_t pos = params->hdr.e_phoff;
@@ -560,8 +560,8 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm,
 	sp &= ~7UL;
 
 	/* stack the load map(s) */
-	len = sizeof(struct elf32_fdpic_loadmap);
-	len += sizeof(struct elf32_fdpic_loadseg) * exec_params->loadmap->nsegs;
+	len = sizeof(struct elf_fdpic_loadmap);
+	len += sizeof(struct elf_fdpic_loadseg) * exec_params->loadmap->nsegs;
 	sp = (sp - len) & ~7UL;
 	exec_params->map_addr = sp;
 
@@ -571,8 +571,8 @@ static int create_elf_fdpic_tables(struct linux_binprm *bprm,
 	current->mm->context.exec_fdpic_loadmap = (unsigned long) sp;
 
 	if (interp_params->loadmap) {
-		len = sizeof(struct elf32_fdpic_loadmap);
-		len += sizeof(struct elf32_fdpic_loadseg) *
+		len = sizeof(struct elf_fdpic_loadmap);
+		len += sizeof(struct elf_fdpic_loadseg) *
 			interp_params->loadmap->nsegs;
 		sp = (sp - len) & ~7UL;
 		interp_params->map_addr = sp;
@@ -740,13 +740,13 @@ static int elf_fdpic_map_file(struct elf_fdpic_params *params,
 			      struct mm_struct *mm,
 			      const char *what)
 {
-	struct elf32_fdpic_loadmap *loadmap;
+	struct elf_fdpic_loadmap *loadmap;
 #ifdef CONFIG_MMU
-	struct elf32_fdpic_loadseg *mseg;
+	struct elf_fdpic_loadseg *mseg;
 	unsigned long load_addr;
 #endif
-	struct elf32_fdpic_loadseg *seg;
-	struct elf32_phdr *phdr;
+	struct elf_fdpic_loadseg *seg;
+	struct elf_phdr *phdr;
 	unsigned nloads, tmp;
 	unsigned long stop;
 	int loop, ret;
@@ -766,7 +766,7 @@ static int elf_fdpic_map_file(struct elf_fdpic_params *params,
 
 	params->loadmap = loadmap;
 
-	loadmap->version = ELF32_FDPIC_LOADMAP_VERSION;
+	loadmap->version = ELF_FDPIC_LOADMAP_VERSION;
 	loadmap->nsegs = nloads;
 
 	/* map the requested LOADs into the memory space */
@@ -839,8 +839,8 @@ static int elf_fdpic_map_file(struct elf_fdpic_params *params,
 			if (phdr->p_vaddr >= seg->p_vaddr &&
 			    phdr->p_vaddr + phdr->p_memsz <=
 			    seg->p_vaddr + seg->p_memsz) {
-				Elf32_Dyn __user *dyn;
-				Elf32_Sword d_tag;
+				Elf_Dyn __user *dyn;
+				Elf_Sword d_tag;
 
 				params->dynamic_addr =
 					(phdr->p_vaddr - seg->p_vaddr) +
@@ -850,11 +850,11 @@ static int elf_fdpic_map_file(struct elf_fdpic_params *params,
 				 * one item, and that the last item is a NULL
 				 * entry */
 				if (phdr->p_memsz == 0 ||
-				    phdr->p_memsz % sizeof(Elf32_Dyn) != 0)
+				    phdr->p_memsz % sizeof(Elf_Dyn) != 0)
 					goto dynamic_error;
 
-				tmp = phdr->p_memsz / sizeof(Elf32_Dyn);
-				dyn = (Elf32_Dyn __user *)params->dynamic_addr;
+				tmp = phdr->p_memsz / sizeof(Elf_Dyn);
+				dyn = (Elf_Dyn __user *)params->dynamic_addr;
 				if (get_user(d_tag, &dyn[tmp - 1].d_tag) ||
 				    d_tag != 0)
 					goto dynamic_error;
@@ -923,8 +923,8 @@ static int elf_fdpic_map_file_constdisp_on_uclinux(
 	struct file *file,
 	struct mm_struct *mm)
 {
-	struct elf32_fdpic_loadseg *seg;
-	struct elf32_phdr *phdr;
+	struct elf_fdpic_loadseg *seg;
+	struct elf_phdr *phdr;
 	unsigned long load_addr, base = ULONG_MAX, top = 0, maddr = 0;
 	int loop, ret;
 
@@ -1007,8 +1007,8 @@ static int elf_fdpic_map_file_by_direct_mmap(struct elf_fdpic_params *params,
 					     struct file *file,
 					     struct mm_struct *mm)
 {
-	struct elf32_fdpic_loadseg *seg;
-	struct elf32_phdr *phdr;
+	struct elf_fdpic_loadseg *seg;
+	struct elf_phdr *phdr;
 	unsigned long load_addr, delta_vaddr;
 	int loop, dvset;
 

include/linux/elf-fdpic.h

@@ -10,13 +10,25 @@
 
 #include <uapi/linux/elf-fdpic.h>
 
+#if ELF_CLASS == ELFCLASS32
+#define Elf_Sword			Elf32_Sword
+#define elf_fdpic_loadseg		elf32_fdpic_loadseg
+#define elf_fdpic_loadmap		elf32_fdpic_loadmap
+#define ELF_FDPIC_LOADMAP_VERSION	ELF32_FDPIC_LOADMAP_VERSION
+#else
+#define Elf_Sword			Elf64_Sxword
+#define elf_fdpic_loadmap		elf64_fdpic_loadmap
+#define elf_fdpic_loadseg		elf64_fdpic_loadseg
+#define ELF_FDPIC_LOADMAP_VERSION	ELF64_FDPIC_LOADMAP_VERSION
+#endif
+
 /*
  * binfmt binary parameters structure
  */
 struct elf_fdpic_params {
 	struct elfhdr			hdr;		/* ref copy of ELF header */
 	struct elf_phdr			*phdrs;		/* ref copy of PT_PHDR table */
-	struct elf32_fdpic_loadmap	*loadmap;	/* loadmap to be passed to userspace */
+	struct elf_fdpic_loadmap	*loadmap;	/* loadmap to be passed to userspace */
 	unsigned long			elfhdr_addr;	/* mapped ELF header user address */
 	unsigned long			ph_addr;	/* mapped PT_PHDR user address */
 	unsigned long			map_addr;	/* mapped loadmap user address */

include/uapi/linux/elf-fdpic.h

@@ -32,4 +32,19 @@ struct elf32_fdpic_loadmap {
 
 #define ELF32_FDPIC_LOADMAP_VERSION	0x0000
 
+/* segment mappings for ELF FDPIC libraries/executables/interpreters */
+struct elf64_fdpic_loadseg {
+	Elf64_Addr	addr;		/* core address to which mapped */
+	Elf64_Addr	p_vaddr;	/* VMA recorded in file */
+	Elf64_Word	p_memsz;	/* allocation size recorded in file */
+};
+
+struct elf64_fdpic_loadmap {
+	Elf64_Half	version;	/* version of these structures, just in case... */
+	Elf64_Half	nsegs;		/* number of segments */
+	struct elf64_fdpic_loadseg segs[];
+};
+
+#define ELF64_FDPIC_LOADMAP_VERSION	0x0000
+
 #endif /* _UAPI_LINUX_ELF_FDPIC_H */