From d8e7cb39acc66316106ef8bda9b76f9f3cbbcad0 Mon Sep 17 00:00:00 2001 From: Alexey Dobriyan Date: Tue, 14 May 2019 15:43:51 -0700 Subject: [PATCH] fs/binfmt_elf.c: extract PROT_* calculations There are two places where mapping protections are calculated: one for executable, another one for interpreter -- take them out. ELF read and execute permissions are interchanged with Linux PROT_READ and PROT_EXEC, microoptimizations are welcome! Link: http://lkml.kernel.org/r/20190417213413.GB26474@avx2 Signed-off-by: Alexey Dobriyan Reviewed-by: Andrew Morton Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/binfmt_elf.c | 30 ++++++++++++++++-------------- 1 file changed, 16 insertions(+), 14 deletions(-) diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 512646da8255..31f264bd5126 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -524,6 +524,19 @@ static inline int arch_check_elf(struct elfhdr *ehdr, bool has_interp, #endif /* !CONFIG_ARCH_BINFMT_ELF_STATE */ +static inline int make_prot(u32 p_flags) +{ + int prot = 0; + + if (p_flags & PF_R) + prot |= PROT_READ; + if (p_flags & PF_W) + prot |= PROT_WRITE; + if (p_flags & PF_X) + prot |= PROT_EXEC; + return prot; +} + /* This is much more generalized than the library routine read function, so we keep this separate. Technically the library read function is only provided so that we can read a.out libraries that have @@ -563,16 +576,10 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex, for (i = 0; i < interp_elf_ex->e_phnum; i++, eppnt++) { if (eppnt->p_type == PT_LOAD) { int elf_type = MAP_PRIVATE | MAP_DENYWRITE; - int elf_prot = 0; + int elf_prot = make_prot(eppnt->p_flags); unsigned long vaddr = 0; unsigned long k, map_addr; - if (eppnt->p_flags & PF_R) - elf_prot = PROT_READ; - if (eppnt->p_flags & PF_W) - elf_prot |= PROT_WRITE; - if (eppnt->p_flags & PF_X) - elf_prot |= PROT_EXEC; vaddr = eppnt->p_vaddr; if (interp_elf_ex->e_type == ET_EXEC || load_addr_set) elf_type |= MAP_FIXED_NOREPLACE; @@ -891,7 +898,7 @@ out_free_interp: the correct location in memory. */ for(i = 0, elf_ppnt = elf_phdata; i < loc->elf_ex.e_phnum; i++, elf_ppnt++) { - int elf_prot = 0, elf_flags, elf_fixed = MAP_FIXED_NOREPLACE; + int elf_prot, elf_flags, elf_fixed = MAP_FIXED_NOREPLACE; unsigned long k, vaddr; unsigned long total_size = 0; @@ -932,12 +939,7 @@ out_free_interp: elf_fixed = MAP_FIXED; } - if (elf_ppnt->p_flags & PF_R) - elf_prot |= PROT_READ; - if (elf_ppnt->p_flags & PF_W) - elf_prot |= PROT_WRITE; - if (elf_ppnt->p_flags & PF_X) - elf_prot |= PROT_EXEC; + elf_prot = make_prot(elf_ppnt->p_flags); elf_flags = MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE; -- 2.30.2