106 lines
3.9 KiB
Diff
106 lines
3.9 KiB
Diff
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From 04e4f2b18c8de1389d1e00fef0f42a8099910daf Mon Sep 17 00:00:00 2001
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From: Mike Frysinger <vapier@gentoo.org>
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Date: Wed, 6 Jan 2010 17:23:17 +0000
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Subject: FDPIC: Respect PT_GNU_STACK exec protection markings when creating NOMMU stack
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From: Mike Frysinger <vapier@gentoo.org>
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commit 04e4f2b18c8de1389d1e00fef0f42a8099910daf upstream.
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The current code will load the stack size and protection markings, but
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then only use the markings in the MMU code path. The NOMMU code path
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always passes PROT_EXEC to the mmap() call. While this doesn't matter
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to most people whilst the code is running, it will cause a pointless
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icache flush when starting every FDPIC application. Typically this
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icache flush will be of a region on the order of 128KB in size, or may
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be the entire icache, depending on the facilities available on the CPU.
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In the case where the arch default behaviour seems to be desired
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(EXSTACK_DEFAULT), we probe VM_STACK_FLAGS for VM_EXEC to determine
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whether we should be setting PROT_EXEC or not.
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For arches that support an MPU (Memory Protection Unit - an MMU without
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the virtual mapping capability), setting PROT_EXEC or not will make an
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important difference.
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It should be noted that this change also affects the executability of
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the brk region, since ELF-FDPIC has that share with the stack. However,
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this is probably irrelevant as NOMMU programs aren't likely to use the
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brk region, preferring instead allocation via mmap().
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Signed-off-by: Mike Frysinger <vapier@gentoo.org>
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Signed-off-by: David Howells <dhowells@redhat.com>
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Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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---
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arch/blackfin/include/asm/page.h | 5 +++++
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arch/frv/include/asm/page.h | 2 --
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fs/binfmt_elf_fdpic.c | 13 +++++++++++--
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3 files changed, 16 insertions(+), 4 deletions(-)
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--- a/arch/blackfin/include/asm/page.h
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+++ b/arch/blackfin/include/asm/page.h
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@@ -10,4 +10,9 @@
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#include <asm-generic/page.h>
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#define MAP_NR(addr) (((unsigned long)(addr)-PAGE_OFFSET) >> PAGE_SHIFT)
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+#define VM_DATA_DEFAULT_FLAGS \
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+ (VM_READ | VM_WRITE | \
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+ ((current->personality & READ_IMPLIES_EXEC) ? VM_EXEC : 0 ) | \
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+ VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
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+
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#endif
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--- a/arch/frv/include/asm/page.h
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+++ b/arch/frv/include/asm/page.h
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@@ -63,12 +63,10 @@ extern unsigned long max_pfn;
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#define virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
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-#ifdef CONFIG_MMU
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#define VM_DATA_DEFAULT_FLAGS \
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(VM_READ | VM_WRITE | \
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((current->personality & READ_IMPLIES_EXEC) ? VM_EXEC : 0 ) | \
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VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
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-#endif
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#endif /* __ASSEMBLY__ */
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--- a/fs/binfmt_elf_fdpic.c
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+++ b/fs/binfmt_elf_fdpic.c
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@@ -171,6 +171,9 @@ static int load_elf_fdpic_binary(struct
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#ifdef ELF_FDPIC_PLAT_INIT
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unsigned long dynaddr;
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#endif
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+#ifndef CONFIG_MMU
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+ unsigned long stack_prot;
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+#endif
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struct file *interpreter = NULL; /* to shut gcc up */
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char *interpreter_name = NULL;
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int executable_stack;
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@@ -316,6 +319,8 @@ static int load_elf_fdpic_binary(struct
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* defunct, deceased, etc. after this point we have to exit via
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* error_kill */
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set_personality(PER_LINUX_FDPIC);
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+ if (elf_read_implies_exec(&exec_params.hdr, executable_stack))
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+ current->personality |= READ_IMPLIES_EXEC;
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set_binfmt(&elf_fdpic_format);
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current->mm->start_code = 0;
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@@ -377,9 +382,13 @@ static int load_elf_fdpic_binary(struct
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if (stack_size < PAGE_SIZE * 2)
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stack_size = PAGE_SIZE * 2;
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+ stack_prot = PROT_READ | PROT_WRITE;
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+ if (executable_stack == EXSTACK_ENABLE_X ||
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+ (executable_stack == EXSTACK_DEFAULT && VM_STACK_FLAGS & VM_EXEC))
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+ stack_prot |= PROT_EXEC;
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+
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down_write(¤t->mm->mmap_sem);
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- current->mm->start_brk = do_mmap(NULL, 0, stack_size,
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- PROT_READ | PROT_WRITE | PROT_EXEC,
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+ current->mm->start_brk = do_mmap(NULL, 0, stack_size, stack_prot,
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MAP_PRIVATE | MAP_ANONYMOUS | MAP_GROWSDOWN,
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0);
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