From: Kees Cook <keescook@xxxxxxxxxxxx> Subject: exec: introduce finalize_exec() before start_thread() Provide a final callback into fs/exec.c before start_thread() takes over, to handle any last-minute changes, like the coming restoration of the stack limit. Link: http://lkml.kernel.org/r/1518638796-20819-3-git-send-email-keescook@xxxxxxxxxxxx Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Ben Hutchings <ben@xxxxxxxxxxxxxxx> Cc: Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx> Cc: Brad Spengler <spender@xxxxxxxxxxxxxx> Cc: Greg KH <greg@xxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: "Jason A. Donenfeld" <Jason@xxxxxxxxx> Cc: Laura Abbott <labbott@xxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: Willy Tarreau <w@xxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/binfmt_aout.c | 1 + fs/binfmt_elf.c | 1 + fs/binfmt_elf_fdpic.c | 1 + fs/binfmt_flat.c | 1 + fs/exec.c | 6 ++++++ include/linux/binfmts.h | 1 + 6 files changed, 11 insertions(+) diff -puN fs/binfmt_aout.c~exec-introduce-finalize_exec-before-start_thread fs/binfmt_aout.c --- a/fs/binfmt_aout.c~exec-introduce-finalize_exec-before-start_thread +++ a/fs/binfmt_aout.c @@ -330,6 +330,7 @@ beyond_if: #ifdef __alpha__ regs->gp = ex.a_gpvalue; #endif + finalize_exec(bprm); start_thread(regs, ex.a_entry, current->mm->start_stack); return 0; } diff -puN fs/binfmt_elf.c~exec-introduce-finalize_exec-before-start_thread fs/binfmt_elf.c --- a/fs/binfmt_elf.c~exec-introduce-finalize_exec-before-start_thread +++ a/fs/binfmt_elf.c @@ -1155,6 +1155,7 @@ static int load_elf_binary(struct linux_ ELF_PLAT_INIT(regs, reloc_func_desc); #endif + finalize_exec(bprm); start_thread(regs, elf_entry, bprm->p); retval = 0; out: diff -puN fs/binfmt_elf_fdpic.c~exec-introduce-finalize_exec-before-start_thread fs/binfmt_elf_fdpic.c --- a/fs/binfmt_elf_fdpic.c~exec-introduce-finalize_exec-before-start_thread +++ a/fs/binfmt_elf_fdpic.c @@ -463,6 +463,7 @@ static int load_elf_fdpic_binary(struct dynaddr); #endif + finalize_exec(bprm); /* everything is now ready... get the userspace context ready to roll */ entryaddr = interp_params.entry_addr ?: exec_params.entry_addr; start_thread(regs, entryaddr, current->mm->start_stack); diff -puN fs/binfmt_flat.c~exec-introduce-finalize_exec-before-start_thread fs/binfmt_flat.c --- a/fs/binfmt_flat.c~exec-introduce-finalize_exec-before-start_thread +++ a/fs/binfmt_flat.c @@ -994,6 +994,7 @@ static int load_flat_binary(struct linux FLAT_PLAT_INIT(regs); #endif + finalize_exec(bprm); pr_debug("start_thread(regs=0x%p, entry=0x%lx, start_stack=0x%lx)\n", regs, start_addr, current->mm->start_stack); start_thread(regs, start_addr, current->mm->start_stack); diff -puN fs/exec.c~exec-introduce-finalize_exec-before-start_thread fs/exec.c --- a/fs/exec.c~exec-introduce-finalize_exec-before-start_thread +++ a/fs/exec.c @@ -1384,6 +1384,12 @@ void setup_new_exec(struct linux_binprm } EXPORT_SYMBOL(setup_new_exec); +/* Runs immediately before start_thread() takes over. */ +void finalize_exec(struct linux_binprm *bprm) +{ +} +EXPORT_SYMBOL(finalize_exec); + /* * Prepare credentials and lock ->cred_guard_mutex. * install_exec_creds() commits the new creds and drops the lock. diff -puN include/linux/binfmts.h~exec-introduce-finalize_exec-before-start_thread include/linux/binfmts.h --- a/include/linux/binfmts.h~exec-introduce-finalize_exec-before-start_thread +++ a/include/linux/binfmts.h @@ -118,6 +118,7 @@ extern int __must_check remove_arg_zero( extern int search_binary_handler(struct linux_binprm *); extern int flush_old_exec(struct linux_binprm * bprm); extern void setup_new_exec(struct linux_binprm * bprm); +extern void finalize_exec(struct linux_binprm *bprm); extern void would_dump(struct linux_binprm *, struct file *); extern int suid_dumpable; _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
