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Diffstat (limited to 'fs/exec.c')
-rw-r--r--fs/exec.c202
1 files changed, 120 insertions, 82 deletions
diff --git a/fs/exec.c b/fs/exec.c
index e6e94c626c2c..e19de6a80339 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -242,9 +242,10 @@ static int __bprm_mm_init(struct linux_binprm *bprm)
* use STACK_TOP because that can depend on attributes which aren't
* configured yet.
*/
+ BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
vma->vm_end = STACK_TOP_MAX;
vma->vm_start = vma->vm_end - PAGE_SIZE;
- vma->vm_flags = VM_STACK_FLAGS;
+ vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
INIT_LIST_HEAD(&vma->anon_vma_chain);
err = insert_vm_struct(mm, vma);
@@ -616,6 +617,7 @@ int setup_arg_pages(struct linux_binprm *bprm,
else if (executable_stack == EXSTACK_DISABLE_X)
vm_flags &= ~VM_EXEC;
vm_flags |= mm->def_flags;
+ vm_flags |= VM_STACK_INCOMPLETE_SETUP;
ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
vm_flags);
@@ -630,6 +632,9 @@ int setup_arg_pages(struct linux_binprm *bprm,
goto out_unlock;
}
+ /* mprotect_fixup is overkill to remove the temporary stack flags */
+ vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
+
stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
stack_size = vma->vm_end - vma->vm_start;
/*
@@ -763,7 +768,6 @@ static int de_thread(struct task_struct *tsk)
struct signal_struct *sig = tsk->signal;
struct sighand_struct *oldsighand = tsk->sighand;
spinlock_t *lock = &oldsighand->siglock;
- int count;
if (thread_group_empty(tsk))
goto no_thread_group;
@@ -780,13 +784,13 @@ static int de_thread(struct task_struct *tsk)
spin_unlock_irq(lock);
return -EAGAIN;
}
+
sig->group_exit_task = tsk;
- zap_other_threads(tsk);
+ sig->notify_count = zap_other_threads(tsk);
+ if (!thread_group_leader(tsk))
+ sig->notify_count--;
- /* Account for the thread group leader hanging around: */
- count = thread_group_leader(tsk) ? 1 : 2;
- sig->notify_count = count;
- while (atomic_read(&sig->count) > count) {
+ while (sig->notify_count) {
__set_current_state(TASK_UNINTERRUPTIBLE);
spin_unlock_irq(lock);
schedule();
@@ -1657,12 +1661,15 @@ static int coredump_wait(int exit_code, struct core_state *core_state)
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->mm;
struct completion *vfork_done;
- int core_waiters;
+ int core_waiters = -EBUSY;
init_completion(&core_state->startup);
core_state->dumper.task = tsk;
core_state->dumper.next = NULL;
- core_waiters = zap_threads(tsk, mm, core_state, exit_code);
+
+ down_write(&mm->mmap_sem);
+ if (!mm->core_state)
+ core_waiters = zap_threads(tsk, mm, core_state, exit_code);
up_write(&mm->mmap_sem);
if (unlikely(core_waiters < 0))
@@ -1782,21 +1789,61 @@ static void wait_for_dump_helpers(struct file *file)
}
+/*
+ * uhm_pipe_setup
+ * helper function to customize the process used
+ * to collect the core in userspace. Specifically
+ * it sets up a pipe and installs it as fd 0 (stdin)
+ * for the process. Returns 0 on success, or
+ * PTR_ERR on failure.
+ * Note that it also sets the core limit to 1. This
+ * is a special value that we use to trap recursive
+ * core dumps
+ */
+static int umh_pipe_setup(struct subprocess_info *info)
+{
+ struct file *rp, *wp;
+ struct fdtable *fdt;
+ struct coredump_params *cp = (struct coredump_params *)info->data;
+ struct files_struct *cf = current->files;
+
+ wp = create_write_pipe(0);
+ if (IS_ERR(wp))
+ return PTR_ERR(wp);
+
+ rp = create_read_pipe(wp, 0);
+ if (IS_ERR(rp)) {
+ free_write_pipe(wp);
+ return PTR_ERR(rp);
+ }
+
+ cp->file = wp;
+
+ sys_close(0);
+ fd_install(0, rp);
+ spin_lock(&cf->file_lock);
+ fdt = files_fdtable(cf);
+ FD_SET(0, fdt->open_fds);
+ FD_CLR(0, fdt->close_on_exec);
+ spin_unlock(&cf->file_lock);
+
+ /* and disallow core files too */
+ current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
+
+ return 0;
+}
+
void do_coredump(long signr, int exit_code, struct pt_regs *regs)
{
struct core_state core_state;
char corename[CORENAME_MAX_SIZE + 1];
struct mm_struct *mm = current->mm;
struct linux_binfmt * binfmt;
- struct inode * inode;
const struct cred *old_cred;
struct cred *cred;
int retval = 0;
int flag = 0;
- int ispipe = 0;
- char **helper_argv = NULL;
- int helper_argc = 0;
- int dump_count = 0;
+ int ispipe;
static atomic_t core_dump_count = ATOMIC_INIT(0);
struct coredump_params cprm = {
.signr = signr,
@@ -1815,23 +1862,12 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs)
binfmt = mm->binfmt;
if (!binfmt || !binfmt->core_dump)
goto fail;
-
- cred = prepare_creds();
- if (!cred) {
- retval = -ENOMEM;
+ if (!__get_dumpable(cprm.mm_flags))
goto fail;
- }
- down_write(&mm->mmap_sem);
- /*
- * If another thread got here first, or we are not dumpable, bail out.
- */
- if (mm->core_state || !__get_dumpable(cprm.mm_flags)) {
- up_write(&mm->mmap_sem);
- put_cred(cred);
+ cred = prepare_creds();
+ if (!cred)
goto fail;
- }
-
/*
* We cannot trust fsuid as being the "true" uid of the
* process nor do we know its entire history. We only know it
@@ -1844,10 +1880,8 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs)
}
retval = coredump_wait(exit_code, &core_state);
- if (retval < 0) {
- put_cred(cred);
- goto fail;
- }
+ if (retval < 0)
+ goto fail_creds;
old_cred = override_creds(cred);
@@ -1865,19 +1899,19 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs)
ispipe = format_corename(corename, signr);
unlock_kernel();
- if ((!ispipe) && (cprm.limit < binfmt->min_coredump))
- goto fail_unlock;
-
if (ispipe) {
- if (cprm.limit == 0) {
+ int dump_count;
+ char **helper_argv;
+
+ if (cprm.limit == 1) {
/*
* Normally core limits are irrelevant to pipes, since
* we're not writing to the file system, but we use
- * cprm.limit of 0 here as a speacial value. Any
- * non-zero limit gets set to RLIM_INFINITY below, but
+ * cprm.limit of 1 here as a speacial value. Any
+ * non-1 limit gets set to RLIM_INFINITY below, but
* a limit of 0 skips the dump. This is a consistent
* way to catch recursive crashes. We can still crash
- * if the core_pattern binary sets RLIM_CORE = !0
+ * if the core_pattern binary sets RLIM_CORE = !1
* but it runs as root, and can do lots of stupid things
* Note that we use task_tgid_vnr here to grab the pid
* of the process group leader. That way we get the
@@ -1885,11 +1919,12 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs)
* core_pattern process dies.
*/
printk(KERN_WARNING
- "Process %d(%s) has RLIMIT_CORE set to 0\n",
+ "Process %d(%s) has RLIMIT_CORE set to 1\n",
task_tgid_vnr(current), current->comm);
printk(KERN_WARNING "Aborting core\n");
goto fail_unlock;
}
+ cprm.limit = RLIM_INFINITY;
dump_count = atomic_inc_return(&core_dump_count);
if (core_pipe_limit && (core_pipe_limit < dump_count)) {
@@ -1899,71 +1934,74 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs)
goto fail_dropcount;
}
- helper_argv = argv_split(GFP_KERNEL, corename+1, &helper_argc);
+ helper_argv = argv_split(GFP_KERNEL, corename+1, NULL);
if (!helper_argv) {
printk(KERN_WARNING "%s failed to allocate memory\n",
__func__);
goto fail_dropcount;
}
- cprm.limit = RLIM_INFINITY;
-
- /* SIGPIPE can happen, but it's just never processed */
- if (call_usermodehelper_pipe(helper_argv[0], helper_argv, NULL,
- &cprm.file)) {
+ retval = call_usermodehelper_fns(helper_argv[0], helper_argv,
+ NULL, UMH_WAIT_EXEC, umh_pipe_setup,
+ NULL, &cprm);
+ argv_free(helper_argv);
+ if (retval) {
printk(KERN_INFO "Core dump to %s pipe failed\n",
corename);
- goto fail_dropcount;
+ goto close_fail;
}
- } else
+ } else {
+ struct inode *inode;
+
+ if (cprm.limit < binfmt->min_coredump)
+ goto fail_unlock;
+
cprm.file = filp_open(corename,
O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
0600);
- if (IS_ERR(cprm.file))
- goto fail_dropcount;
- inode = cprm.file->f_path.dentry->d_inode;
- if (inode->i_nlink > 1)
- goto close_fail; /* multiple links - don't dump */
- if (!ispipe && d_unhashed(cprm.file->f_path.dentry))
- goto close_fail;
-
- /* AK: actually i see no reason to not allow this for named pipes etc.,
- but keep the previous behaviour for now. */
- if (!ispipe && !S_ISREG(inode->i_mode))
- goto close_fail;
- /*
- * Dont allow local users get cute and trick others to coredump
- * into their pre-created files:
- * Note, this is not relevant for pipes
- */
- if (!ispipe && (inode->i_uid != current_fsuid()))
- goto close_fail;
- if (!cprm.file->f_op)
- goto close_fail;
- if (!cprm.file->f_op->write)
- goto close_fail;
- if (!ispipe &&
- do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file) != 0)
- goto close_fail;
+ if (IS_ERR(cprm.file))
+ goto fail_unlock;
- retval = binfmt->core_dump(&cprm);
+ inode = cprm.file->f_path.dentry->d_inode;
+ if (inode->i_nlink > 1)
+ goto close_fail;
+ if (d_unhashed(cprm.file->f_path.dentry))
+ goto close_fail;
+ /*
+ * AK: actually i see no reason to not allow this for named
+ * pipes etc, but keep the previous behaviour for now.
+ */
+ if (!S_ISREG(inode->i_mode))
+ goto close_fail;
+ /*
+ * Dont allow local users get cute and trick others to coredump
+ * into their pre-created files.
+ */
+ if (inode->i_uid != current_fsuid())
+ goto close_fail;
+ if (!cprm.file->f_op || !cprm.file->f_op->write)
+ goto close_fail;
+ if (do_truncate(cprm.file->f_path.dentry, 0, 0, cprm.file))
+ goto close_fail;
+ }
+ retval = binfmt->core_dump(&cprm);
if (retval)
current->signal->group_exit_code |= 0x80;
-close_fail:
+
if (ispipe && core_pipe_limit)
wait_for_dump_helpers(cprm.file);
- filp_close(cprm.file, NULL);
+close_fail:
+ if (cprm.file)
+ filp_close(cprm.file, NULL);
fail_dropcount:
- if (dump_count)
+ if (ispipe)
atomic_dec(&core_dump_count);
fail_unlock:
- if (helper_argv)
- argv_free(helper_argv);
-
+ coredump_finish(mm);
revert_creds(old_cred);
+fail_creds:
put_cred(cred);
- coredump_finish(mm);
fail:
return;
}