Commit a62c5b1b authored by Alexey Dobriyan's avatar Alexey Dobriyan Committed by Linus Torvalds
Browse files

fs/binfmt_elf.c: don't copy ELF header around 

ELF header is read into bprm->buf[] by generic execve code.

Save a memcpy and allocate just one header for the interpreter instead
of two headers (64 bytes instead of 128 on 64-bit).

Link: http://lkml.kernel.org/r/20191208171242.GA19716@avx2


Signed-off-by: default avatarAlexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f67ef446

fs/binfmt_elf.c

+27 −28
Original line number Diff line number Diff line
@@ -161,8 +161,9 @@ static int padzero(unsigned long elf_bss) 
#endif



static int

create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec,

		unsigned long load_addr, unsigned long interp_load_addr)

create_elf_tables(struct linux_binprm *bprm, const struct elfhdr *exec,

		unsigned long load_addr, unsigned long interp_load_addr,

		unsigned long e_entry)

{

	unsigned long p = bprm->p;

	int argc = bprm->argc;
@@ -251,7 +252,7 @@ create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec, 
	NEW_AUX_ENT(AT_PHNUM, exec->e_phnum);

	NEW_AUX_ENT(AT_BASE, interp_load_addr);

	NEW_AUX_ENT(AT_FLAGS, 0);

	NEW_AUX_ENT(AT_ENTRY, exec->e_entry);

	NEW_AUX_ENT(AT_ENTRY, e_entry);

	NEW_AUX_ENT(AT_UID, from_kuid_munged(cred->user_ns, cred->uid));

	NEW_AUX_ENT(AT_EUID, from_kuid_munged(cred->user_ns, cred->euid));

	NEW_AUX_ENT(AT_GID, from_kgid_munged(cred->user_ns, cred->gid));
@@ -690,12 +691,13 @@ static int load_elf_binary(struct linux_binprm *bprm) 
	int bss_prot = 0;

	int retval, i;

	unsigned long elf_entry;

	unsigned long e_entry;

	unsigned long interp_load_addr = 0;

	unsigned long start_code, end_code, start_data, end_data;

	unsigned long reloc_func_desc __maybe_unused = 0;

	int executable_stack = EXSTACK_DEFAULT;

	struct elfhdr *elf_ex = (struct elfhdr *)bprm->buf;

	struct {

		struct elfhdr elf_ex;

		struct elfhdr interp_elf_ex;

	} *loc;

	struct arch_elf_state arch_state = INIT_ARCH_ELF_STATE;
@@ -707,29 +709,26 @@ static int load_elf_binary(struct linux_binprm *bprm) 
		goto out_ret;

	}



	/* Get the exec-header */

	loc->elf_ex = *((struct elfhdr *)bprm->buf);



	retval = -ENOEXEC;

	/* First of all, some simple consistency checks */

	if (memcmp(loc->elf_ex.e_ident, ELFMAG, SELFMAG) != 0)

	if (memcmp(elf_ex->e_ident, ELFMAG, SELFMAG) != 0)

		goto out;



	if (loc->elf_ex.e_type != ET_EXEC && loc->elf_ex.e_type != ET_DYN)

	if (elf_ex->e_type != ET_EXEC && elf_ex->e_type != ET_DYN)

		goto out;

	if (!elf_check_arch(&loc->elf_ex))

	if (!elf_check_arch(elf_ex))

		goto out;

	if (elf_check_fdpic(&loc->elf_ex))

	if (elf_check_fdpic(elf_ex))

		goto out;

	if (!bprm->file->f_op->mmap)

		goto out;



	elf_phdata = load_elf_phdrs(&loc->elf_ex, bprm->file);

	elf_phdata = load_elf_phdrs(elf_ex, bprm->file);

	if (!elf_phdata)

		goto out;



	elf_ppnt = elf_phdata;

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

	for (i = 0; i < elf_ex->e_phnum; i++, elf_ppnt++) {

		char *elf_interpreter;



		if (elf_ppnt->p_type != PT_INTERP)
@@ -783,7 +782,7 @@ out_free_interp: 
	}



	elf_ppnt = elf_phdata;

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

	for (i = 0; i < elf_ex->e_phnum; i++, elf_ppnt++)

		switch (elf_ppnt->p_type) {

		case PT_GNU_STACK:

			if (elf_ppnt->p_flags & PF_X)
@@ -793,7 +792,7 @@ out_free_interp: 
			break;



		case PT_LOPROC ... PT_HIPROC:

			retval = arch_elf_pt_proc(&loc->elf_ex, elf_ppnt,

			retval = arch_elf_pt_proc(elf_ex, elf_ppnt,

						  bprm->file, false,

						  &arch_state);

			if (retval)
@@ -837,7 +836,7 @@ out_free_interp: 
	 * still possible to return an error to the code that invoked

	 * the exec syscall.

	 */

	retval = arch_check_elf(&loc->elf_ex,

	retval = arch_check_elf(elf_ex,

				!!interpreter, &loc->interp_elf_ex,

				&arch_state);

	if (retval)
@@ -850,8 +849,8 @@ out_free_interp: 


	/* Do this immediately, since STACK_TOP as used in setup_arg_pages

	   may depend on the personality.  */

	SET_PERSONALITY2(loc->elf_ex, &arch_state);

	if (elf_read_implies_exec(loc->elf_ex, executable_stack))

	SET_PERSONALITY2(*elf_ex, &arch_state);

	if (elf_read_implies_exec(*elf_ex, executable_stack))

		current->personality |= READ_IMPLIES_EXEC;



	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
@@ -878,7 +877,7 @@ out_free_interp: 
	/* Now we do a little grungy work by mmapping the ELF image into

	   the correct location in memory. */

	for(i = 0, elf_ppnt = elf_phdata;

	    i < loc->elf_ex.e_phnum; i++, elf_ppnt++) {

	    i < elf_ex->e_phnum; i++, elf_ppnt++) {

		int elf_prot, elf_flags;

		unsigned long k, vaddr;

		unsigned long total_size = 0;
@@ -922,9 +921,9 @@ out_free_interp: 
		 * If we are loading ET_EXEC or we have already performed

		 * the ET_DYN load_addr calculations, proceed normally.

		 */

		if (loc->elf_ex.e_type == ET_EXEC || load_addr_set) {

		if (elf_ex->e_type == ET_EXEC || load_addr_set) {

			elf_flags |= MAP_FIXED;

		} else if (loc->elf_ex.e_type == ET_DYN) {

		} else if (elf_ex->e_type == ET_DYN) {

			/*

			 * This logic is run once for the first LOAD Program

			 * Header for ET_DYN binaries to calculate the
@@ -973,7 +972,7 @@ out_free_interp: 
			load_bias = ELF_PAGESTART(load_bias - vaddr);



			total_size = total_mapping_size(elf_phdata,

							loc->elf_ex.e_phnum);

							elf_ex->e_phnum);

			if (!total_size) {

				retval = -EINVAL;

				goto out_free_dentry;
@@ -991,7 +990,7 @@ out_free_interp: 
		if (!load_addr_set) {

			load_addr_set = 1;

			load_addr = (elf_ppnt->p_vaddr - elf_ppnt->p_offset);

			if (loc->elf_ex.e_type == ET_DYN) {

			if (elf_ex->e_type == ET_DYN) {

				load_bias += error -

				             ELF_PAGESTART(load_bias + vaddr);

				load_addr += load_bias;
@@ -1032,7 +1031,7 @@ out_free_interp: 
		}

	}



	loc->elf_ex.e_entry += load_bias;

	e_entry = elf_ex->e_entry + load_bias;

	elf_bss += load_bias;

	elf_brk += load_bias;

	start_code += load_bias;
@@ -1075,7 +1074,7 @@ out_free_interp: 
		allow_write_access(interpreter);

		fput(interpreter);

	} else {

		elf_entry = loc->elf_ex.e_entry;

		elf_entry = e_entry;

		if (BAD_ADDR(elf_entry)) {

			retval = -EINVAL;

			goto out_free_dentry;
@@ -1093,8 +1092,8 @@ out_free_interp: 
		goto out;

#endif /* ARCH_HAS_SETUP_ADDITIONAL_PAGES */



	retval = create_elf_tables(bprm, &loc->elf_ex,

			  load_addr, interp_load_addr);

	retval = create_elf_tables(bprm, elf_ex,

			  load_addr, interp_load_addr, e_entry);

	if (retval < 0)

		goto out;

	current->mm->end_code = end_code;
@@ -1112,7 +1111,7 @@ out_free_interp: 
		 * growing down), and into the unused ELF_ET_DYN_BASE region.

		 */

		if (IS_ENABLED(CONFIG_ARCH_HAS_ELF_RANDOMIZE) &&

		    loc->elf_ex.e_type == ET_DYN && !interpreter)

		    elf_ex->e_type == ET_DYN && !interpreter)

			current->mm->brk = current->mm->start_brk =

				ELF_ET_DYN_BASE;

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