diff options
Diffstat (limited to 'arch/arm/kernel/elf.c')
| -rw-r--r-- | arch/arm/kernel/elf.c | 27 |
1 files changed, 23 insertions, 4 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; |