Commit 00e19cee authored by Dave Martin's avatar Dave Martin Committed by Catalin Marinas
Browse files

ELF: Add ELF program property parsing support 



ELF program properties will be needed for detecting whether to
enable optional architecture or ABI features for a new ELF process.

For now, there are no generic properties that we care about, so do
nothing unless CONFIG_ARCH_USE_GNU_PROPERTY=y.

Otherwise, the presence of properties using the PT_PROGRAM_PROPERTY
phdrs entry (if any), and notify each property to the arch code.

For now, the added code is not used.

Signed-off-by: default avatarMark Brown <broonie@kernel.org>
Signed-off-by: default avatarDave Martin <Dave.Martin@arm.com>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent db751e30

fs/binfmt_elf.c

+127 −0
Original line number Diff line number Diff line
@@ -39,12 +39,18 @@ 
#include <linux/sched/coredump.h>

#include <linux/sched/task_stack.h>

#include <linux/sched/cputime.h>

#include <linux/sizes.h>

#include <linux/types.h>

#include <linux/cred.h>

#include <linux/dax.h>

#include <linux/uaccess.h>

#include <asm/param.h>

#include <asm/page.h>



#ifndef ELF_COMPAT

#define ELF_COMPAT 0

#endif



#ifndef user_long_t

#define user_long_t long

#endif
@@ -681,6 +687,111 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex, 
 * libraries.  There is no binary dependent code anywhere else.

 */



static int parse_elf_property(const char *data, size_t *off, size_t datasz,

			      struct arch_elf_state *arch,

			      bool have_prev_type, u32 *prev_type)

{

	size_t o, step;

	const struct gnu_property *pr;

	int ret;



	if (*off == datasz)

		return -ENOENT;



	if (WARN_ON_ONCE(*off > datasz || *off % ELF_GNU_PROPERTY_ALIGN))

		return -EIO;

	o = *off;

	datasz -= *off;



	if (datasz < sizeof(*pr))

		return -ENOEXEC;

	pr = (const struct gnu_property *)(data + o);

	o += sizeof(*pr);

	datasz -= sizeof(*pr);



	if (pr->pr_datasz > datasz)

		return -ENOEXEC;



	WARN_ON_ONCE(o % ELF_GNU_PROPERTY_ALIGN);

	step = round_up(pr->pr_datasz, ELF_GNU_PROPERTY_ALIGN);

	if (step > datasz)

		return -ENOEXEC;



	/* Properties are supposed to be unique and sorted on pr_type: */

	if (have_prev_type && pr->pr_type <= *prev_type)

		return -ENOEXEC;

	*prev_type = pr->pr_type;



	ret = arch_parse_elf_property(pr->pr_type, data + o,

				      pr->pr_datasz, ELF_COMPAT, arch);

	if (ret)

		return ret;



	*off = o + step;

	return 0;

}



#define NOTE_DATA_SZ SZ_1K

#define GNU_PROPERTY_TYPE_0_NAME "GNU"

#define NOTE_NAME_SZ (sizeof(GNU_PROPERTY_TYPE_0_NAME))



static int parse_elf_properties(struct file *f, const struct elf_phdr *phdr,

				struct arch_elf_state *arch)

{

	union {

		struct elf_note nhdr;

		char data[NOTE_DATA_SZ];

	} note;

	loff_t pos;

	ssize_t n;

	size_t off, datasz;

	int ret;

	bool have_prev_type;

	u32 prev_type;



	if (!IS_ENABLED(CONFIG_ARCH_USE_GNU_PROPERTY) || !phdr)

		return 0;



	/* load_elf_binary() shouldn't call us unless this is true... */

	if (WARN_ON_ONCE(phdr->p_type != PT_GNU_PROPERTY))

		return -ENOEXEC;



	/* If the properties are crazy large, that's too bad (for now): */

	if (phdr->p_filesz > sizeof(note))

		return -ENOEXEC;



	pos = phdr->p_offset;

	n = kernel_read(f, &note, phdr->p_filesz, &pos);



	BUILD_BUG_ON(sizeof(note) < sizeof(note.nhdr) + NOTE_NAME_SZ);

	if (n < 0 || n < sizeof(note.nhdr) + NOTE_NAME_SZ)

		return -EIO;



	if (note.nhdr.n_type != NT_GNU_PROPERTY_TYPE_0 ||

	    note.nhdr.n_namesz != NOTE_NAME_SZ ||

	    strncmp(note.data + sizeof(note.nhdr),

		    GNU_PROPERTY_TYPE_0_NAME, n - sizeof(note.nhdr)))

		return -ENOEXEC;



	off = round_up(sizeof(note.nhdr) + NOTE_NAME_SZ,

		       ELF_GNU_PROPERTY_ALIGN);

	if (off > n)

		return -ENOEXEC;



	if (note.nhdr.n_descsz > n - off)

		return -ENOEXEC;

	datasz = off + note.nhdr.n_descsz;



	have_prev_type = false;

	do {

		ret = parse_elf_property(note.data, &off, datasz, arch,

					 have_prev_type, &prev_type);

		have_prev_type = true;

	} while (!ret);



	return ret == -ENOENT ? 0 : ret;

}



static int load_elf_binary(struct linux_binprm *bprm)

{

	struct file *interpreter = NULL; /* to shut gcc up */
@@ -688,6 +799,7 @@ static int load_elf_binary(struct linux_binprm *bprm) 
	int load_addr_set = 0;

	unsigned long error;

	struct elf_phdr *elf_ppnt, *elf_phdata, *interp_elf_phdata = NULL;

	struct elf_phdr *elf_property_phdata = NULL;

	unsigned long elf_bss, elf_brk;

	int bss_prot = 0;

	int retval, i;
@@ -733,6 +845,11 @@ static int load_elf_binary(struct linux_binprm *bprm) 
	for (i = 0; i < elf_ex->e_phnum; i++, elf_ppnt++) {

		char *elf_interpreter;



		if (elf_ppnt->p_type == PT_GNU_PROPERTY) {

			elf_property_phdata = elf_ppnt;

			continue;

		}



		if (elf_ppnt->p_type != PT_INTERP)

			continue;
@@ -820,9 +937,14 @@ static int load_elf_binary(struct linux_binprm *bprm) 
			goto out_free_dentry;



		/* Pass PT_LOPROC..PT_HIPROC headers to arch code */

		elf_property_phdata = NULL;

		elf_ppnt = interp_elf_phdata;

		for (i = 0; i < loc->interp_elf_ex.e_phnum; i++, elf_ppnt++)

			switch (elf_ppnt->p_type) {

			case PT_GNU_PROPERTY:

				elf_property_phdata = elf_ppnt;

				break;



			case PT_LOPROC ... PT_HIPROC:

				retval = arch_elf_pt_proc(&loc->interp_elf_ex,

							  elf_ppnt, interpreter,
@@ -833,6 +955,11 @@ static int load_elf_binary(struct linux_binprm *bprm) 
			}

	}



	retval = parse_elf_properties(interpreter ?: bprm->file,

				      elf_property_phdata, &arch_state);

	if (retval)

		goto out_free_dentry;



	/*

	 * Allow arch code to reject the ELF at this point, whilst it's

	 * still possible to return an error to the code that invoked

fs/compat_binfmt_elf.c

+4 −0
Original line number Diff line number Diff line
@@ -17,6 +17,8 @@ 
#include <linux/elfcore-compat.h>

#include <linux/time.h>



#define ELF_COMPAT	1



/*

 * Rename the basic ELF layout types to refer to the 32-bit class of files.

 */
@@ -28,11 +30,13 @@ 
#undef	elf_shdr

#undef	elf_note

#undef	elf_addr_t

#undef	ELF_GNU_PROPERTY_ALIGN

#define elfhdr		elf32_hdr

#define elf_phdr	elf32_phdr

#define elf_shdr	elf32_shdr

#define elf_note	elf32_note

#define elf_addr_t	Elf32_Addr

#define ELF_GNU_PROPERTY_ALIGN	ELF32_GNU_PROPERTY_ALIGN



/*

 * Some data types as stored in coredump.

include/linux/elf.h

+19 −0
Original line number Diff line number Diff line
@@ -22,6 +22,9 @@ 
	SET_PERSONALITY(ex)

#endif



#define ELF32_GNU_PROPERTY_ALIGN	4

#define ELF64_GNU_PROPERTY_ALIGN	8



#if ELF_CLASS == ELFCLASS32



extern Elf32_Dyn _DYNAMIC [];
@@ -32,6 +35,7 @@ extern Elf32_Dyn _DYNAMIC []; 
#define elf_addr_t	Elf32_Off

#define Elf_Half	Elf32_Half

#define Elf_Word	Elf32_Word

#define ELF_GNU_PROPERTY_ALIGN	ELF32_GNU_PROPERTY_ALIGN



#else
@@ -43,6 +47,7 @@ extern Elf64_Dyn _DYNAMIC []; 
#define elf_addr_t	Elf64_Off

#define Elf_Half	Elf64_Half

#define Elf_Word	Elf64_Word

#define ELF_GNU_PROPERTY_ALIGN	ELF64_GNU_PROPERTY_ALIGN



#endif
@@ -68,4 +73,18 @@ struct gnu_property { 
	u32 pr_datasz;

};



struct arch_elf_state;



#ifndef CONFIG_ARCH_USE_GNU_PROPERTY

static inline int arch_parse_elf_property(u32 type, const void *data,

					  size_t datasz, bool compat,

					  struct arch_elf_state *arch)

{

	return 0;

}

#else

extern int arch_parse_elf_property(u32 type, const void *data, size_t datasz,

				   bool compat, struct arch_elf_state *arch);

#endif



#endif /* _LINUX_ELF_H */

include/uapi/linux/elf.h

+4 −0
Original line number Diff line number Diff line
@@ -368,6 +368,7 @@ typedef struct elf64_shdr { 
 * Notes used in ET_CORE. Architectures export some of the arch register sets

 * using the corresponding note types via the PTRACE_GETREGSET and

 * PTRACE_SETREGSET requests.

 * The note name for all these is "LINUX".

 */

#define NT_PRSTATUS	1

#define NT_PRFPREG	2
@@ -430,6 +431,9 @@ typedef struct elf64_shdr { 
#define NT_MIPS_FP_MODE	0x801		/* MIPS floating-point mode */

#define NT_MIPS_MSA	0x802		/* MIPS SIMD registers */



/* Note types with note name "GNU" */

#define NT_GNU_PROPERTY_TYPE_0	5



/* Note header in a PT_NOTE section */

typedef struct elf32_note {

  Elf32_Word	n_namesz;	/* Name size */