* current->executable is only used by the procfs. This allows a dispatch
* table to check for several different types of binary formats. We keep
* trying until we recognize the file or we run out of supported binary
- * formats.
+ * formats.
*/
#include <linux/slab.h>
#include <linux/pipe_fs_i.h>
#include <linux/oom.h>
#include <linux/compat.h>
+#include <linux/user_namespace.h>
#include <asm/uaccess.h>
#include <asm/mmu_context.h>
{
struct page *page;
int ret;
+ unsigned int gup_flags = FOLL_FORCE;
#ifdef CONFIG_STACK_GROWSUP
if (write) {
return NULL;
}
#endif
- ret = get_user_pages(current, bprm->mm, pos,
- 1, write, 1, &page, NULL);
+
+ if (write)
+ gup_flags |= FOLL_WRITE;
+
+ ret = get_user_pages(current, bprm->mm, pos, 1, gup_flags,
+ &page, NULL);
if (ret <= 0)
return NULL;
if (write) {
unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
- struct rlimit *rlim;
+ unsigned long ptr_size, limit;
+
+ /*
+ * Since the stack will hold pointers to the strings, we
+ * must account for them as well.
+ *
+ * The size calculation is the entire vma while each arg page is
+ * built, so each time we get here it's calculating how far it
+ * is currently (rather than each call being just the newly
+ * added size from the arg page). As a result, we need to
+ * always add the entire size of the pointers, so that on the
+ * last call to get_arg_page() we'll actually have the entire
+ * correct size.
+ */
+ ptr_size = (bprm->argc + bprm->envc) * sizeof(void *);
+ if (ptr_size > ULONG_MAX - size)
+ goto fail;
+ size += ptr_size;
acct_arg_size(bprm, size / PAGE_SIZE);
return page;
/*
- * Limit to 1/4-th the stack size for the argv+env strings.
+ * Limit to 1/4 of the max stack size or 3/4 of _STK_LIM
+ * (whichever is smaller) for the argv+env strings.
* This ensures that:
* - the remaining binfmt code will not run out of stack space,
* - the program will have a reasonable amount of stack left
* to work from.
*/
- rlim = current->signal->rlim;
- if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) {
- put_page(page);
- return NULL;
- }
+ limit = _STK_LIM / 4 * 3;
+ limit = min(limit, rlimit(RLIMIT_STACK) / 4);
+ if (size > limit)
+ goto fail;
}
return page;
+
+fail:
+ put_page(page);
+ return NULL;
}
static void put_arg_page(struct page *page)
return -EAGAIN;
}
-char *get_task_comm(char *buf, struct task_struct *tsk)
+char *__get_task_comm(char *buf, size_t buf_size, struct task_struct *tsk)
{
- /* buf must be at least sizeof(tsk->comm) in size */
task_lock(tsk);
- strncpy(buf, tsk->comm, sizeof(tsk->comm));
+ strncpy(buf, tsk->comm, buf_size);
task_unlock(tsk);
return buf;
}
-EXPORT_SYMBOL_GPL(get_task_comm);
+EXPORT_SYMBOL_GPL(__get_task_comm);
/*
* These functions flushes out all traces of the currently running executable
flush_thread();
current->personality &= ~bprm->per_clear;
+ /*
+ * We have to apply CLOEXEC before we change whether the process is
+ * dumpable (in setup_new_exec) to avoid a race with a process in userspace
+ * trying to access the should-be-closed file descriptors of a process
+ * undergoing exec(2).
+ */
+ do_close_on_exec(current->files);
return 0;
out:
void would_dump(struct linux_binprm *bprm, struct file *file)
{
- if (inode_permission(file_inode(file), MAY_READ) < 0)
+ struct inode *inode = file_inode(file);
+ if (inode_permission(inode, MAY_READ) < 0) {
+ struct user_namespace *old, *user_ns;
bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;
+
+ /* Ensure mm->user_ns contains the executable */
+ user_ns = old = bprm->mm->user_ns;
+ while ((user_ns != &init_user_ns) &&
+ !privileged_wrt_inode_uidgid(user_ns, inode))
+ user_ns = user_ns->parent;
+
+ if (old != user_ns) {
+ bprm->mm->user_ns = get_user_ns(user_ns);
+ put_user_ns(old);
+ }
+ }
}
EXPORT_SYMBOL(would_dump);
!gid_eq(bprm->cred->gid, current_egid())) {
current->pdeath_signal = 0;
} else {
- would_dump(bprm, bprm->file);
if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)
set_dumpable(current->mm, suid_dumpable);
}
group */
current->self_exec_id++;
flush_signal_handlers(current, 0);
- do_close_on_exec(current->files);
}
EXPORT_SYMBOL(setup_new_exec);
unsigned n_fs;
if (p->ptrace) {
- if (p->ptrace & PT_PTRACE_CAP)
+ if (ptracer_capable(p, current_user_ns()))
bprm->unsafe |= LSM_UNSAFE_PTRACE_CAP;
else
bprm->unsafe |= LSM_UNSAFE_PTRACE;
if (retval < 0)
goto out;
+ would_dump(bprm, bprm->file);
+
retval = exec_binprm(bprm);
if (retval < 0)
goto out;
current->fs->in_exec = 0;
current->in_execve = 0;
acct_update_integrals(current);
- task_numa_free(current);
+ task_numa_free(current, false);
free_bprm(bprm);
kfree(pathbuf);
putname(filename);
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