diff options
| -rw-r--r-- | arch/arm/kernel/elf.c | 27 | ||||
| -rw-r--r-- | arch/arm64/include/asm/elf.h | 23 | ||||
| -rw-r--r-- | arch/x86/include/asm/elf.h | 22 | ||||
| -rw-r--r-- | fs/compat_binfmt_elf.c | 5 |
4 files changed, 71 insertions, 6 deletions
diff --git a/arch/arm/kernel/elf.c b/arch/arm/kernel/elf.c index 182422981386..254ab7138c85 100644 --- a/arch/arm/kernel/elf.c +++ b/arch/arm/kernel/elf.c @@ -78,13 +78,32 @@ void elf_set_personality(const struct elf32_hdr *x) EXPORT_SYMBOL(elf_set_personality); /* - * Set READ_IMPLIES_EXEC if: - * - the binary requires an executable stack - * - we're running on a CPU which doesn't support NX. + * An executable for which elf_read_implies_exec() returns TRUE will + * have the READ_IMPLIES_EXEC personality flag set automatically. + * + * The decision process for determining the results are: + * + * CPU: | lacks NX* | has NX | + * ELF: | | | + * ---------------------|------------|------------| + * missing PT_GNU_STACK | exec-all | exec-all | + * PT_GNU_STACK == RWX | exec-all | exec-stack | + * PT_GNU_STACK == RW | exec-all | exec-none | + * + * exec-all : all PROT_READ user mappings are executable, except when + * backed by files on a noexec-filesystem. + * exec-none : only PROT_EXEC user mappings are executable. + * exec-stack: only the stack and PROT_EXEC user mappings are executable. + * + * *this column has no architectural effect: NX markings are ignored by + * hardware, but may have behavioral effects when "wants X" collides with + * "cannot be X" constraints in memory permission flags, as in + * https://lkml.kernel.org/r/20190418055759.GA3155@mellanox.com + * */ int arm_elf_read_implies_exec(int executable_stack) { - if (executable_stack != EXSTACK_DISABLE_X) + if (executable_stack == EXSTACK_DEFAULT) return 1; if (cpu_architecture() < CPU_ARCH_ARMv6) return 1; diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h index 4f00d50585a4..8d1c8dcb87fd 100644 --- a/arch/arm64/include/asm/elf.h +++ b/arch/arm64/include/asm/elf.h @@ -96,7 +96,28 @@ */ #define elf_check_arch(x) ((x)->e_machine == EM_AARCH64) -#define elf_read_implies_exec(ex,stk) (stk != EXSTACK_DISABLE_X) +/* + * An executable for which elf_read_implies_exec() returns TRUE will + * have the READ_IMPLIES_EXEC personality flag set automatically. + * + * The decision process for determining the results are: + * + * CPU*: | arm32 | arm64 | + * ELF: | | | + * ---------------------|------------|------------| + * missing PT_GNU_STACK | exec-all | exec-none | + * PT_GNU_STACK == RWX | exec-stack | exec-stack | + * PT_GNU_STACK == RW | exec-none | exec-none | + * + * exec-all : all PROT_READ user mappings are executable, except when + * backed by files on a noexec-filesystem. + * exec-none : only PROT_EXEC user mappings are executable. + * exec-stack: only the stack and PROT_EXEC user mappings are executable. + * + * *all arm64 CPUs support NX, so there is no "lacks NX" column. + * + */ +#define compat_elf_read_implies_exec(ex, stk) (stk == EXSTACK_DEFAULT) #define CORE_DUMP_USE_REGSET #define ELF_EXEC_PAGESIZE PAGE_SIZE diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h index 69c0f892e310..452beed7892b 100644 --- a/arch/x86/include/asm/elf.h +++ b/arch/x86/include/asm/elf.h @@ -281,9 +281,29 @@ extern u32 elf_hwcap2; /* * An executable for which elf_read_implies_exec() returns TRUE will * have the READ_IMPLIES_EXEC personality flag set automatically. + * + * The decision process for determining the results are: + * + * CPU: | lacks NX* | has NX, ia32 | has NX, x86_64 | + * ELF: | | | | + * ---------------------|------------|------------------|----------------| + * missing PT_GNU_STACK | exec-all | exec-all | exec-none | + * PT_GNU_STACK == RWX | exec-stack | exec-stack | exec-stack | + * PT_GNU_STACK == RW | exec-none | exec-none | exec-none | + * + * exec-all : all PROT_READ user mappings are executable, except when + * backed by files on a noexec-filesystem. + * exec-none : only PROT_EXEC user mappings are executable. + * exec-stack: only the stack and PROT_EXEC user mappings are executable. + * + * *this column has no architectural effect: NX markings are ignored by + * hardware, but may have behavioral effects when "wants X" collides with + * "cannot be X" constraints in memory permission flags, as in + * https://lkml.kernel.org/r/20190418055759.GA3155@mellanox.com + * */ #define elf_read_implies_exec(ex, executable_stack) \ - (executable_stack != EXSTACK_DISABLE_X) + (mmap_is_ia32() && executable_stack == EXSTACK_DEFAULT) struct task_struct; diff --git a/fs/compat_binfmt_elf.c b/fs/compat_binfmt_elf.c index e61f3fe8e32a..2d24c765cbd7 100644 --- a/fs/compat_binfmt_elf.c +++ b/fs/compat_binfmt_elf.c @@ -117,6 +117,11 @@ #define arch_setup_additional_pages compat_arch_setup_additional_pages #endif +#ifdef compat_elf_read_implies_exec +#undef elf_read_implies_exec +#define elf_read_implies_exec compat_elf_read_implies_exec +#endif + /* * Rename a few of the symbols that binfmt_elf.c will define. * These are all local so the names don't really matter, but it |