[PATCH v3 01/13] fs: binfmt_elf_efpic: add architecture hook elf_arch_finalize_exec

[PATCH v3 01/13] fs: binfmt_elf_efpic: add architecture hook elf_arch_finalize_exec

[Hajime Tazaki]

FDPIC ELF loader adds an architecture hook at the end of loading
binaries to finalize the mapped memory before moving toward exec
function.  The hook is used by UML under !MMU when translating
syscall/sysenter instructions before calling execve.

Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Kees Cook <kees@kernel.org>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-mm@kvack.org
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
---
 fs/binfmt_elf_fdpic.c     | 10 ++++++++++
 include/linux/elf-fdpic.h |  3 +++
 2 files changed, 13 insertions(+)

diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 4fe5bb9f1b1f..ab16fdf475b0 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -175,6 +175,12 @@ static int elf_fdpic_fetch_phdrs(struct elf_fdpic_params *params,
 	return 0;
 }
 
+int __weak elf_arch_finalize_exec(struct elf_fdpic_params *exec_params,
+				  struct elf_fdpic_params *interp_params)
+{
+	return 0;
+}
+
 /*****************************************************************************/
 /*
  * load an fdpic binary into various bits of memory
@@ -457,6 +463,10 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm)
 			    dynaddr);
 #endif
 
+	retval = elf_arch_finalize_exec(&exec_params, &interp_params);
+	if (retval)
+		goto error;
+
 	finalize_exec(bprm);
 	/* everything is now ready... get the userspace context ready to roll */
 	entryaddr = interp_params.entry_addr ?: exec_params.entry_addr;
diff --git a/include/linux/elf-fdpic.h b/include/linux/elf-fdpic.h
index e533f4513194..e7fd85a1d10f 100644
--- a/include/linux/elf-fdpic.h
+++ b/include/linux/elf-fdpic.h
@@ -56,4 +56,7 @@ extern void elf_fdpic_arch_lay_out_mm(struct elf_fdpic_params *exec_params,
 				      unsigned long *start_brk);
 #endif
 
+extern int elf_arch_finalize_exec(struct elf_fdpic_params *exec_params,
+				  struct elf_fdpic_params *interp_params);
+
 #endif /* _LINUX_ELF_FDPIC_H */
-- 
2.43.0

[PATCH v3 02/13] x86/um: nommu: elf loader for fdpic

[Hajime Tazaki]

As UML supports CONFIG_MMU=n case, it has to use an alternate ELF
loader, FDPIC ELF loader.  In this commit, we added necessary
definitions in the arch, as UML has not been used so far.  It also
updates Kconfig file to use BINFMT_ELF_FDPIC under !MMU environment.

Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: linux-mm@kvack.org
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
Signed-off-by: Ricardo Koller <ricarkol@google.com>
---
 arch/um/include/asm/Kbuild           |  1 +
 arch/um/include/asm/mmu.h            |  5 +++++
 arch/um/include/asm/ptrace-generic.h |  6 ++++++
 arch/x86/um/asm/elf.h                |  8 ++++++--
 arch/x86/um/asm/module.h             | 24 ------------------------
 fs/Kconfig.binfmt                    |  2 +-
 6 files changed, 19 insertions(+), 27 deletions(-)
 delete mode 100644 arch/x86/um/asm/module.h

diff --git a/arch/um/include/asm/Kbuild b/arch/um/include/asm/Kbuild
index 428f2c5158c2..04ab3b653a48 100644
--- a/arch/um/include/asm/Kbuild
+++ b/arch/um/include/asm/Kbuild
@@ -13,6 +13,7 @@ generic-y += irq_work.h
 generic-y += kdebug.h
 generic-y += mcs_spinlock.h
 generic-y += mmiowb.h
+generic-y += module.h
 generic-y += module.lds.h
 generic-y += param.h
 generic-y += parport.h
diff --git a/arch/um/include/asm/mmu.h b/arch/um/include/asm/mmu.h
index a3eaca41ff61..01422b761aa0 100644
--- a/arch/um/include/asm/mmu.h
+++ b/arch/um/include/asm/mmu.h
@@ -14,6 +14,11 @@ typedef struct mm_context {
 	/* Address range in need of a TLB sync */
 	unsigned long sync_tlb_range_from;
 	unsigned long sync_tlb_range_to;
+
+#ifdef CONFIG_BINFMT_ELF_FDPIC
+	unsigned long   exec_fdpic_loadmap;
+	unsigned long   interp_fdpic_loadmap;
+#endif
 } mm_context_t;
 
 #endif
diff --git a/arch/um/include/asm/ptrace-generic.h b/arch/um/include/asm/ptrace-generic.h
index 4696f24d1492..4ff844bcb1cd 100644
--- a/arch/um/include/asm/ptrace-generic.h
+++ b/arch/um/include/asm/ptrace-generic.h
@@ -29,6 +29,12 @@ struct pt_regs {
 
 #define PTRACE_OLDSETOPTIONS 21
 
+#ifdef CONFIG_BINFMT_ELF_FDPIC
+#define PTRACE_GETFDPIC		31
+#define PTRACE_GETFDPIC_EXEC	0
+#define PTRACE_GETFDPIC_INTERP	1
+#endif
+
 struct task_struct;
 
 extern long subarch_ptrace(struct task_struct *child, long request,
diff --git a/arch/x86/um/asm/elf.h b/arch/x86/um/asm/elf.h
index 62ed5d68a978..33f69f1eac10 100644
--- a/arch/x86/um/asm/elf.h
+++ b/arch/x86/um/asm/elf.h
@@ -9,6 +9,7 @@
 #include <skas.h>
 
 #define CORE_DUMP_USE_REGSET
+#define ELF_FDPIC_CORE_EFLAGS  0
 
 #ifdef CONFIG_X86_32
 
@@ -190,8 +191,11 @@ extern int arch_setup_additional_pages(struct linux_binprm *bprm,
 
 extern unsigned long um_vdso_addr;
 #define AT_SYSINFO_EHDR 33
-#define ARCH_DLINFO	NEW_AUX_ENT(AT_SYSINFO_EHDR, um_vdso_addr)
-
+#define ARCH_DLINFO						\
+do {								\
+	NEW_AUX_ENT(AT_SYSINFO_EHDR, um_vdso_addr);		\
+	NEW_AUX_ENT(AT_MINSIGSTKSZ, 0);			\
+} while (0)
 #endif
 
 typedef unsigned long elf_greg_t;
diff --git a/arch/x86/um/asm/module.h b/arch/x86/um/asm/module.h
deleted file mode 100644
index a3b061d66082..000000000000
--- a/arch/x86/um/asm/module.h
+++ /dev/null
@@ -1,24 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef __UM_MODULE_H
-#define __UM_MODULE_H
-
-/* UML is simple */
-struct mod_arch_specific
-{
-};
-
-#ifdef CONFIG_X86_32
-
-#define Elf_Shdr Elf32_Shdr
-#define Elf_Sym Elf32_Sym
-#define Elf_Ehdr Elf32_Ehdr
-
-#else
-
-#define Elf_Shdr Elf64_Shdr
-#define Elf_Sym Elf64_Sym
-#define Elf_Ehdr Elf64_Ehdr
-
-#endif
-
-#endif
diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt
index bd2f530e5740..419ba0282806 100644
--- a/fs/Kconfig.binfmt
+++ b/fs/Kconfig.binfmt
@@ -58,7 +58,7 @@ config ARCH_USE_GNU_PROPERTY
 config BINFMT_ELF_FDPIC
 	bool "Kernel support for FDPIC ELF binaries"
 	default y if !BINFMT_ELF
-	depends on ARM || ((M68K || RISCV || SUPERH || XTENSA) && !MMU)
+	depends on ARM || ((M68K || RISCV || SUPERH || UML || XTENSA) && !MMU)
 	select ELFCORE
 	help
 	  ELF FDPIC binaries are based on ELF, but allow the individual load
-- 
2.43.0

Re: [PATCH v3 02/13] x86/um: nommu: elf loader for fdpic

[Johannes Berg]

On Tue, 2024-12-03 at 13:23 +0900, Hajime Tazaki wrote:
> 
>  arch/um/include/asm/Kbuild           |  1 +
> 
>  arch/x86/um/asm/module.h             | 24 ------------------------
> 

These changes could be a separate cleanup?

johannes

Re: [PATCH v3 02/13] x86/um: nommu: elf loader for fdpic

[Hajime Tazaki]

On Thu, 05 Dec 2024 01:20:51 +0900,
Johannes Berg wrote:
> 
> On Tue, 2024-12-03 at 13:23 +0900, Hajime Tazaki wrote:
> > 
> >  arch/um/include/asm/Kbuild           |  1 +
> > 
> >  arch/x86/um/asm/module.h             | 24 ------------------------
> > 
> 
> These changes could be a separate cleanup?

agree.  will do it.

-- Hajime