![Linus Torvalds](/assets/img/avatar_default.png)
'flush_old_exec()' is the point of no return when doing an execve(), and it is pretty badly misnamed. It doesn't just flush the old executable environment, it also starts up the new one. Which is very inconvenient for things like setting up the new personality, because we want the new personality to affect the starting of the new environment, but at the same time we do _not_ want the new personality to take effect if flushing the old one fails. As a result, the x86-64 '32-bit' personality is actually done using this insane "I'm going to change the ABI, but I haven't done it yet" bit (TIF_ABI_PENDING), with SET_PERSONALITY() not actually setting the personality, but just the "pending" bit, so that "flush_thread()" can do the actual personality magic. This patch in no way changes any of that insanity, but it does split the 'flush_old_exec()' function up into a preparatory part that can fail (still called flush_old_exec()), and a new part that will actually set up the new exec environment (setup_new_exec()). All callers are changed to trivially comply with the new world order. Signed-off-by: H. Peter Anvin <hpa@zytor.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
484 lines
13 KiB
C
484 lines
13 KiB
C
/*
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* linux/fs/binfmt_aout.c
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*
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* Copyright (C) 1991, 1992, 1996 Linus Torvalds
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*/
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#include <linux/module.h>
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#include <linux/time.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/mman.h>
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#include <linux/a.out.h>
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#include <linux/errno.h>
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#include <linux/signal.h>
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#include <linux/string.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/stat.h>
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#include <linux/fcntl.h>
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#include <linux/ptrace.h>
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#include <linux/user.h>
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#include <linux/slab.h>
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#include <linux/binfmts.h>
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#include <linux/personality.h>
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#include <linux/init.h>
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#include <asm/system.h>
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#include <asm/uaccess.h>
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#include <asm/cacheflush.h>
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#include <asm/a.out-core.h>
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static int load_aout_binary(struct linux_binprm *, struct pt_regs * regs);
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static int load_aout_library(struct file*);
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static int aout_core_dump(struct coredump_params *cprm);
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static struct linux_binfmt aout_format = {
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.module = THIS_MODULE,
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.load_binary = load_aout_binary,
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.load_shlib = load_aout_library,
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.core_dump = aout_core_dump,
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.min_coredump = PAGE_SIZE
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};
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#define BAD_ADDR(x) ((unsigned long)(x) >= TASK_SIZE)
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static int set_brk(unsigned long start, unsigned long end)
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{
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start = PAGE_ALIGN(start);
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end = PAGE_ALIGN(end);
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if (end > start) {
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unsigned long addr;
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down_write(¤t->mm->mmap_sem);
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addr = do_brk(start, end - start);
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up_write(¤t->mm->mmap_sem);
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if (BAD_ADDR(addr))
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return addr;
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}
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return 0;
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}
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/*
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* These are the only things you should do on a core-file: use only these
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* macros to write out all the necessary info.
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*/
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static int dump_write(struct file *file, const void *addr, int nr)
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{
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return file->f_op->write(file, addr, nr, &file->f_pos) == nr;
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}
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#define DUMP_WRITE(addr, nr) \
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if (!dump_write(file, (void *)(addr), (nr))) \
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goto end_coredump;
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#define DUMP_SEEK(offset) \
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if (file->f_op->llseek) { \
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if (file->f_op->llseek(file,(offset),0) != (offset)) \
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goto end_coredump; \
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} else file->f_pos = (offset)
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/*
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* Routine writes a core dump image in the current directory.
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* Currently only a stub-function.
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*
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* Note that setuid/setgid files won't make a core-dump if the uid/gid
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* changed due to the set[u|g]id. It's enforced by the "current->mm->dumpable"
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* field, which also makes sure the core-dumps won't be recursive if the
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* dumping of the process results in another error..
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*/
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static int aout_core_dump(struct coredump_params *cprm)
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{
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struct file *file = cprm->file;
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mm_segment_t fs;
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int has_dumped = 0;
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unsigned long dump_start, dump_size;
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struct user dump;
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#ifdef __alpha__
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# define START_DATA(u) (u.start_data)
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#else
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# define START_DATA(u) ((u.u_tsize << PAGE_SHIFT) + u.start_code)
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#endif
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# define START_STACK(u) (u.start_stack)
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fs = get_fs();
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set_fs(KERNEL_DS);
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has_dumped = 1;
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current->flags |= PF_DUMPCORE;
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strncpy(dump.u_comm, current->comm, sizeof(dump.u_comm));
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dump.u_ar0 = offsetof(struct user, regs);
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dump.signal = cprm->signr;
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aout_dump_thread(cprm->regs, &dump);
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/* If the size of the dump file exceeds the rlimit, then see what would happen
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if we wrote the stack, but not the data area. */
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if ((dump.u_dsize + dump.u_ssize+1) * PAGE_SIZE > cprm->limit)
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dump.u_dsize = 0;
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/* Make sure we have enough room to write the stack and data areas. */
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if ((dump.u_ssize + 1) * PAGE_SIZE > cprm->limit)
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dump.u_ssize = 0;
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/* make sure we actually have a data and stack area to dump */
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set_fs(USER_DS);
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if (!access_ok(VERIFY_READ, (void __user *)START_DATA(dump), dump.u_dsize << PAGE_SHIFT))
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dump.u_dsize = 0;
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if (!access_ok(VERIFY_READ, (void __user *)START_STACK(dump), dump.u_ssize << PAGE_SHIFT))
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dump.u_ssize = 0;
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set_fs(KERNEL_DS);
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/* struct user */
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DUMP_WRITE(&dump,sizeof(dump));
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/* Now dump all of the user data. Include malloced stuff as well */
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DUMP_SEEK(PAGE_SIZE);
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/* now we start writing out the user space info */
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set_fs(USER_DS);
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/* Dump the data area */
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if (dump.u_dsize != 0) {
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dump_start = START_DATA(dump);
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dump_size = dump.u_dsize << PAGE_SHIFT;
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DUMP_WRITE(dump_start,dump_size);
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}
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/* Now prepare to dump the stack area */
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if (dump.u_ssize != 0) {
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dump_start = START_STACK(dump);
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dump_size = dump.u_ssize << PAGE_SHIFT;
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DUMP_WRITE(dump_start,dump_size);
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}
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/* Finally dump the task struct. Not be used by gdb, but could be useful */
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set_fs(KERNEL_DS);
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DUMP_WRITE(current,sizeof(*current));
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end_coredump:
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set_fs(fs);
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return has_dumped;
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}
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/*
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* create_aout_tables() parses the env- and arg-strings in new user
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* memory and creates the pointer tables from them, and puts their
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* addresses on the "stack", returning the new stack pointer value.
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*/
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static unsigned long __user *create_aout_tables(char __user *p, struct linux_binprm * bprm)
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{
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char __user * __user *argv;
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char __user * __user *envp;
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unsigned long __user *sp;
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int argc = bprm->argc;
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int envc = bprm->envc;
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sp = (void __user *)((-(unsigned long)sizeof(char *)) & (unsigned long) p);
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#ifdef __alpha__
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/* whee.. test-programs are so much fun. */
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put_user(0, --sp);
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put_user(0, --sp);
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if (bprm->loader) {
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put_user(0, --sp);
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put_user(1003, --sp);
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put_user(bprm->loader, --sp);
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put_user(1002, --sp);
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}
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put_user(bprm->exec, --sp);
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put_user(1001, --sp);
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#endif
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sp -= envc+1;
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envp = (char __user * __user *) sp;
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sp -= argc+1;
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argv = (char __user * __user *) sp;
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#ifndef __alpha__
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put_user((unsigned long) envp,--sp);
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put_user((unsigned long) argv,--sp);
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#endif
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put_user(argc,--sp);
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current->mm->arg_start = (unsigned long) p;
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while (argc-->0) {
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char c;
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put_user(p,argv++);
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do {
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get_user(c,p++);
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} while (c);
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}
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put_user(NULL,argv);
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current->mm->arg_end = current->mm->env_start = (unsigned long) p;
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while (envc-->0) {
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char c;
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put_user(p,envp++);
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do {
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get_user(c,p++);
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} while (c);
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}
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put_user(NULL,envp);
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current->mm->env_end = (unsigned long) p;
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return sp;
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}
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/*
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* These are the functions used to load a.out style executables and shared
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* libraries. There is no binary dependent code anywhere else.
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*/
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static int load_aout_binary(struct linux_binprm * bprm, struct pt_regs * regs)
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{
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struct exec ex;
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unsigned long error;
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unsigned long fd_offset;
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unsigned long rlim;
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int retval;
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ex = *((struct exec *) bprm->buf); /* exec-header */
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if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != OMAGIC &&
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N_MAGIC(ex) != QMAGIC && N_MAGIC(ex) != NMAGIC) ||
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N_TRSIZE(ex) || N_DRSIZE(ex) ||
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i_size_read(bprm->file->f_path.dentry->d_inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
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return -ENOEXEC;
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}
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/*
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* Requires a mmap handler. This prevents people from using a.out
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* as part of an exploit attack against /proc-related vulnerabilities.
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*/
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if (!bprm->file->f_op || !bprm->file->f_op->mmap)
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return -ENOEXEC;
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fd_offset = N_TXTOFF(ex);
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/* Check initial limits. This avoids letting people circumvent
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* size limits imposed on them by creating programs with large
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* arrays in the data or bss.
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*/
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rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
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if (rlim >= RLIM_INFINITY)
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rlim = ~0;
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if (ex.a_data + ex.a_bss > rlim)
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return -ENOMEM;
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/* Flush all traces of the currently running executable */
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retval = flush_old_exec(bprm);
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if (retval)
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return retval;
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/* OK, This is the point of no return */
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#ifdef __alpha__
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SET_AOUT_PERSONALITY(bprm, ex);
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#else
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set_personality(PER_LINUX);
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#endif
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setup_new_exec(bprm);
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current->mm->end_code = ex.a_text +
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(current->mm->start_code = N_TXTADDR(ex));
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current->mm->end_data = ex.a_data +
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(current->mm->start_data = N_DATADDR(ex));
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current->mm->brk = ex.a_bss +
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(current->mm->start_brk = N_BSSADDR(ex));
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current->mm->free_area_cache = current->mm->mmap_base;
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current->mm->cached_hole_size = 0;
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install_exec_creds(bprm);
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current->flags &= ~PF_FORKNOEXEC;
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if (N_MAGIC(ex) == OMAGIC) {
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unsigned long text_addr, map_size;
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loff_t pos;
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text_addr = N_TXTADDR(ex);
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#ifdef __alpha__
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pos = fd_offset;
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map_size = ex.a_text+ex.a_data + PAGE_SIZE - 1;
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#else
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pos = 32;
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map_size = ex.a_text+ex.a_data;
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#endif
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down_write(¤t->mm->mmap_sem);
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error = do_brk(text_addr & PAGE_MASK, map_size);
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up_write(¤t->mm->mmap_sem);
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if (error != (text_addr & PAGE_MASK)) {
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send_sig(SIGKILL, current, 0);
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return error;
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}
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error = bprm->file->f_op->read(bprm->file,
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(char __user *)text_addr,
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ex.a_text+ex.a_data, &pos);
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if ((signed long)error < 0) {
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send_sig(SIGKILL, current, 0);
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return error;
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}
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flush_icache_range(text_addr, text_addr+ex.a_text+ex.a_data);
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} else {
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if ((ex.a_text & 0xfff || ex.a_data & 0xfff) &&
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(N_MAGIC(ex) != NMAGIC) && printk_ratelimit())
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{
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printk(KERN_NOTICE "executable not page aligned\n");
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}
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if ((fd_offset & ~PAGE_MASK) != 0 && printk_ratelimit())
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{
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printk(KERN_WARNING
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"fd_offset is not page aligned. Please convert program: %s\n",
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bprm->file->f_path.dentry->d_name.name);
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}
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if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
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loff_t pos = fd_offset;
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down_write(¤t->mm->mmap_sem);
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do_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
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up_write(¤t->mm->mmap_sem);
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bprm->file->f_op->read(bprm->file,
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(char __user *)N_TXTADDR(ex),
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ex.a_text+ex.a_data, &pos);
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flush_icache_range((unsigned long) N_TXTADDR(ex),
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(unsigned long) N_TXTADDR(ex) +
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ex.a_text+ex.a_data);
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goto beyond_if;
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}
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down_write(¤t->mm->mmap_sem);
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error = do_mmap(bprm->file, N_TXTADDR(ex), ex.a_text,
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PROT_READ | PROT_EXEC,
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MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
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fd_offset);
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up_write(¤t->mm->mmap_sem);
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if (error != N_TXTADDR(ex)) {
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send_sig(SIGKILL, current, 0);
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return error;
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}
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down_write(¤t->mm->mmap_sem);
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error = do_mmap(bprm->file, N_DATADDR(ex), ex.a_data,
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PROT_READ | PROT_WRITE | PROT_EXEC,
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MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE,
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fd_offset + ex.a_text);
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up_write(¤t->mm->mmap_sem);
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if (error != N_DATADDR(ex)) {
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send_sig(SIGKILL, current, 0);
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return error;
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}
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}
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beyond_if:
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set_binfmt(&aout_format);
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retval = set_brk(current->mm->start_brk, current->mm->brk);
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if (retval < 0) {
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send_sig(SIGKILL, current, 0);
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return retval;
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}
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retval = setup_arg_pages(bprm, STACK_TOP, EXSTACK_DEFAULT);
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if (retval < 0) {
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/* Someone check-me: is this error path enough? */
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send_sig(SIGKILL, current, 0);
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return retval;
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}
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current->mm->start_stack =
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(unsigned long) create_aout_tables((char __user *) bprm->p, bprm);
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#ifdef __alpha__
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regs->gp = ex.a_gpvalue;
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#endif
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start_thread(regs, ex.a_entry, current->mm->start_stack);
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return 0;
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}
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static int load_aout_library(struct file *file)
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{
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struct inode * inode;
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unsigned long bss, start_addr, len;
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unsigned long error;
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int retval;
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struct exec ex;
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inode = file->f_path.dentry->d_inode;
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retval = -ENOEXEC;
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error = kernel_read(file, 0, (char *) &ex, sizeof(ex));
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if (error != sizeof(ex))
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goto out;
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/* We come in here for the regular a.out style of shared libraries */
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if ((N_MAGIC(ex) != ZMAGIC && N_MAGIC(ex) != QMAGIC) || N_TRSIZE(ex) ||
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N_DRSIZE(ex) || ((ex.a_entry & 0xfff) && N_MAGIC(ex) == ZMAGIC) ||
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i_size_read(inode) < ex.a_text+ex.a_data+N_SYMSIZE(ex)+N_TXTOFF(ex)) {
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goto out;
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}
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/*
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* Requires a mmap handler. This prevents people from using a.out
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* as part of an exploit attack against /proc-related vulnerabilities.
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*/
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if (!file->f_op || !file->f_op->mmap)
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goto out;
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if (N_FLAGS(ex))
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goto out;
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/* For QMAGIC, the starting address is 0x20 into the page. We mask
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this off to get the starting address for the page */
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start_addr = ex.a_entry & 0xfffff000;
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if ((N_TXTOFF(ex) & ~PAGE_MASK) != 0) {
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loff_t pos = N_TXTOFF(ex);
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if (printk_ratelimit())
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{
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printk(KERN_WARNING
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"N_TXTOFF is not page aligned. Please convert library: %s\n",
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file->f_path.dentry->d_name.name);
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}
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down_write(¤t->mm->mmap_sem);
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do_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
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up_write(¤t->mm->mmap_sem);
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file->f_op->read(file, (char __user *)start_addr,
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ex.a_text + ex.a_data, &pos);
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flush_icache_range((unsigned long) start_addr,
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(unsigned long) start_addr + ex.a_text + ex.a_data);
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retval = 0;
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goto out;
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}
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/* Now use mmap to map the library into memory. */
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down_write(¤t->mm->mmap_sem);
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error = do_mmap(file, start_addr, ex.a_text + ex.a_data,
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PROT_READ | PROT_WRITE | PROT_EXEC,
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MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE,
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N_TXTOFF(ex));
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up_write(¤t->mm->mmap_sem);
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retval = error;
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if (error != start_addr)
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goto out;
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len = PAGE_ALIGN(ex.a_text + ex.a_data);
|
|
bss = ex.a_text + ex.a_data + ex.a_bss;
|
|
if (bss > len) {
|
|
down_write(¤t->mm->mmap_sem);
|
|
error = do_brk(start_addr + len, bss - len);
|
|
up_write(¤t->mm->mmap_sem);
|
|
retval = error;
|
|
if (error != start_addr + len)
|
|
goto out;
|
|
}
|
|
retval = 0;
|
|
out:
|
|
return retval;
|
|
}
|
|
|
|
static int __init init_aout_binfmt(void)
|
|
{
|
|
return register_binfmt(&aout_format);
|
|
}
|
|
|
|
static void __exit exit_aout_binfmt(void)
|
|
{
|
|
unregister_binfmt(&aout_format);
|
|
}
|
|
|
|
core_initcall(init_aout_binfmt);
|
|
module_exit(exit_aout_binfmt);
|
|
MODULE_LICENSE("GPL");
|