v4.19.13 snapshot.
diff --git a/fs/exec.c b/fs/exec.c
new file mode 100644
index 0000000..1ebf6e5
--- /dev/null
+++ b/fs/exec.c
@@ -0,0 +1,2000 @@
+/*
+ * linux/fs/exec.c
+ *
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ */
+
+/*
+ * #!-checking implemented by tytso.
+ */
+/*
+ * Demand-loading implemented 01.12.91 - no need to read anything but
+ * the header into memory. The inode of the executable is put into
+ * "current->executable", and page faults do the actual loading. Clean.
+ *
+ * Once more I can proudly say that linux stood up to being changed: it
+ * was less than 2 hours work to get demand-loading completely implemented.
+ *
+ * Demand loading changed July 1993 by Eric Youngdale. Use mmap instead,
+ * 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.
+ */
+
+#include <linux/slab.h>
+#include <linux/file.h>
+#include <linux/fdtable.h>
+#include <linux/mm.h>
+#include <linux/vmacache.h>
+#include <linux/stat.h>
+#include <linux/fcntl.h>
+#include <linux/swap.h>
+#include <linux/string.h>
+#include <linux/init.h>
+#include <linux/sched/mm.h>
+#include <linux/sched/coredump.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/numa_balancing.h>
+#include <linux/sched/task.h>
+#include <linux/pagemap.h>
+#include <linux/perf_event.h>
+#include <linux/highmem.h>
+#include <linux/spinlock.h>
+#include <linux/key.h>
+#include <linux/personality.h>
+#include <linux/binfmts.h>
+#include <linux/utsname.h>
+#include <linux/pid_namespace.h>
+#include <linux/module.h>
+#include <linux/namei.h>
+#include <linux/mount.h>
+#include <linux/security.h>
+#include <linux/syscalls.h>
+#include <linux/tsacct_kern.h>
+#include <linux/cn_proc.h>
+#include <linux/audit.h>
+#include <linux/tracehook.h>
+#include <linux/kmod.h>
+#include <linux/fsnotify.h>
+#include <linux/fs_struct.h>
+#include <linux/pipe_fs_i.h>
+#include <linux/oom.h>
+#include <linux/compat.h>
+#include <linux/vmalloc.h>
+
+#include <linux/uaccess.h>
+#include <asm/mmu_context.h>
+#include <asm/tlb.h>
+
+#include <trace/events/task.h>
+#include "internal.h"
+
+#include <trace/events/sched.h>
+
+int suid_dumpable = 0;
+
+static LIST_HEAD(formats);
+static DEFINE_RWLOCK(binfmt_lock);
+
+void __register_binfmt(struct linux_binfmt * fmt, int insert)
+{
+ BUG_ON(!fmt);
+ if (WARN_ON(!fmt->load_binary))
+ return;
+ write_lock(&binfmt_lock);
+ insert ? list_add(&fmt->lh, &formats) :
+ list_add_tail(&fmt->lh, &formats);
+ write_unlock(&binfmt_lock);
+}
+
+EXPORT_SYMBOL(__register_binfmt);
+
+void unregister_binfmt(struct linux_binfmt * fmt)
+{
+ write_lock(&binfmt_lock);
+ list_del(&fmt->lh);
+ write_unlock(&binfmt_lock);
+}
+
+EXPORT_SYMBOL(unregister_binfmt);
+
+static inline void put_binfmt(struct linux_binfmt * fmt)
+{
+ module_put(fmt->module);
+}
+
+bool path_noexec(const struct path *path)
+{
+ return (path->mnt->mnt_flags & MNT_NOEXEC) ||
+ (path->mnt->mnt_sb->s_iflags & SB_I_NOEXEC);
+}
+
+#ifdef CONFIG_USELIB
+/*
+ * Note that a shared library must be both readable and executable due to
+ * security reasons.
+ *
+ * Also note that we take the address to load from from the file itself.
+ */
+SYSCALL_DEFINE1(uselib, const char __user *, library)
+{
+ struct linux_binfmt *fmt;
+ struct file *file;
+ struct filename *tmp = getname(library);
+ int error = PTR_ERR(tmp);
+ static const struct open_flags uselib_flags = {
+ .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
+ .acc_mode = MAY_READ | MAY_EXEC,
+ .intent = LOOKUP_OPEN,
+ .lookup_flags = LOOKUP_FOLLOW,
+ };
+
+ if (IS_ERR(tmp))
+ goto out;
+
+ file = do_filp_open(AT_FDCWD, tmp, &uselib_flags);
+ putname(tmp);
+ error = PTR_ERR(file);
+ if (IS_ERR(file))
+ goto out;
+
+ error = -EINVAL;
+ if (!S_ISREG(file_inode(file)->i_mode))
+ goto exit;
+
+ error = -EACCES;
+ if (path_noexec(&file->f_path))
+ goto exit;
+
+ fsnotify_open(file);
+
+ error = -ENOEXEC;
+
+ read_lock(&binfmt_lock);
+ list_for_each_entry(fmt, &formats, lh) {
+ if (!fmt->load_shlib)
+ continue;
+ if (!try_module_get(fmt->module))
+ continue;
+ read_unlock(&binfmt_lock);
+ error = fmt->load_shlib(file);
+ read_lock(&binfmt_lock);
+ put_binfmt(fmt);
+ if (error != -ENOEXEC)
+ break;
+ }
+ read_unlock(&binfmt_lock);
+exit:
+ fput(file);
+out:
+ return error;
+}
+#endif /* #ifdef CONFIG_USELIB */
+
+#ifdef CONFIG_MMU
+/*
+ * The nascent bprm->mm is not visible until exec_mmap() but it can
+ * use a lot of memory, account these pages in current->mm temporary
+ * for oom_badness()->get_mm_rss(). Once exec succeeds or fails, we
+ * change the counter back via acct_arg_size(0).
+ */
+static void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
+{
+ struct mm_struct *mm = current->mm;
+ long diff = (long)(pages - bprm->vma_pages);
+
+ if (!mm || !diff)
+ return;
+
+ bprm->vma_pages = pages;
+ add_mm_counter(mm, MM_ANONPAGES, diff);
+}
+
+static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
+ int write)
+{
+ struct page *page;
+ int ret;
+ unsigned int gup_flags = FOLL_FORCE;
+
+#ifdef CONFIG_STACK_GROWSUP
+ if (write) {
+ ret = expand_downwards(bprm->vma, pos);
+ if (ret < 0)
+ return NULL;
+ }
+#endif
+
+ if (write)
+ gup_flags |= FOLL_WRITE;
+
+ /*
+ * We are doing an exec(). 'current' is the process
+ * doing the exec and bprm->mm is the new process's mm.
+ */
+ ret = get_user_pages_remote(current, bprm->mm, pos, 1, gup_flags,
+ &page, NULL, NULL);
+ if (ret <= 0)
+ return NULL;
+
+ if (write) {
+ unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
+ 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);
+
+ /*
+ * We've historically supported up to 32 pages (ARG_MAX)
+ * of argument strings even with small stacks
+ */
+ if (size <= ARG_MAX)
+ return page;
+
+ /*
+ * 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.
+ */
+ limit = _STK_LIM / 4 * 3;
+ limit = min(limit, bprm->rlim_stack.rlim_cur / 4);
+ if (size > limit)
+ goto fail;
+ }
+
+ return page;
+
+fail:
+ put_page(page);
+ return NULL;
+}
+
+static void put_arg_page(struct page *page)
+{
+ put_page(page);
+}
+
+static void free_arg_pages(struct linux_binprm *bprm)
+{
+}
+
+static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
+ struct page *page)
+{
+ flush_cache_page(bprm->vma, pos, page_to_pfn(page));
+}
+
+static int __bprm_mm_init(struct linux_binprm *bprm)
+{
+ int err;
+ struct vm_area_struct *vma = NULL;
+ struct mm_struct *mm = bprm->mm;
+
+ bprm->vma = vma = vm_area_alloc(mm);
+ if (!vma)
+ return -ENOMEM;
+ vma_set_anonymous(vma);
+
+ if (down_write_killable(&mm->mmap_sem)) {
+ err = -EINTR;
+ goto err_free;
+ }
+
+ /*
+ * Place the stack at the largest stack address the architecture
+ * supports. Later, we'll move this to an appropriate place. We don't
+ * use STACK_TOP because that can depend on attributes which aren't
+ * configured yet.
+ */
+ BUILD_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_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
+ vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
+
+ err = insert_vm_struct(mm, vma);
+ if (err)
+ goto err;
+
+ mm->stack_vm = mm->total_vm = 1;
+ arch_bprm_mm_init(mm, vma);
+ up_write(&mm->mmap_sem);
+ bprm->p = vma->vm_end - sizeof(void *);
+ return 0;
+err:
+ up_write(&mm->mmap_sem);
+err_free:
+ bprm->vma = NULL;
+ vm_area_free(vma);
+ return err;
+}
+
+static bool valid_arg_len(struct linux_binprm *bprm, long len)
+{
+ return len <= MAX_ARG_STRLEN;
+}
+
+#else
+
+static inline void acct_arg_size(struct linux_binprm *bprm, unsigned long pages)
+{
+}
+
+static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
+ int write)
+{
+ struct page *page;
+
+ page = bprm->page[pos / PAGE_SIZE];
+ if (!page && write) {
+ page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
+ if (!page)
+ return NULL;
+ bprm->page[pos / PAGE_SIZE] = page;
+ }
+
+ return page;
+}
+
+static void put_arg_page(struct page *page)
+{
+}
+
+static void free_arg_page(struct linux_binprm *bprm, int i)
+{
+ if (bprm->page[i]) {
+ __free_page(bprm->page[i]);
+ bprm->page[i] = NULL;
+ }
+}
+
+static void free_arg_pages(struct linux_binprm *bprm)
+{
+ int i;
+
+ for (i = 0; i < MAX_ARG_PAGES; i++)
+ free_arg_page(bprm, i);
+}
+
+static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
+ struct page *page)
+{
+}
+
+static int __bprm_mm_init(struct linux_binprm *bprm)
+{
+ bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
+ return 0;
+}
+
+static bool valid_arg_len(struct linux_binprm *bprm, long len)
+{
+ return len <= bprm->p;
+}
+
+#endif /* CONFIG_MMU */
+
+/*
+ * Create a new mm_struct and populate it with a temporary stack
+ * vm_area_struct. We don't have enough context at this point to set the stack
+ * flags, permissions, and offset, so we use temporary values. We'll update
+ * them later in setup_arg_pages().
+ */
+static int bprm_mm_init(struct linux_binprm *bprm)
+{
+ int err;
+ struct mm_struct *mm = NULL;
+
+ bprm->mm = mm = mm_alloc();
+ err = -ENOMEM;
+ if (!mm)
+ goto err;
+
+ /* Save current stack limit for all calculations made during exec. */
+ task_lock(current->group_leader);
+ bprm->rlim_stack = current->signal->rlim[RLIMIT_STACK];
+ task_unlock(current->group_leader);
+
+ err = __bprm_mm_init(bprm);
+ if (err)
+ goto err;
+
+ return 0;
+
+err:
+ if (mm) {
+ bprm->mm = NULL;
+ mmdrop(mm);
+ }
+
+ return err;
+}
+
+struct user_arg_ptr {
+#ifdef CONFIG_COMPAT
+ bool is_compat;
+#endif
+ union {
+ const char __user *const __user *native;
+#ifdef CONFIG_COMPAT
+ const compat_uptr_t __user *compat;
+#endif
+ } ptr;
+};
+
+static const char __user *get_user_arg_ptr(struct user_arg_ptr argv, int nr)
+{
+ const char __user *native;
+
+#ifdef CONFIG_COMPAT
+ if (unlikely(argv.is_compat)) {
+ compat_uptr_t compat;
+
+ if (get_user(compat, argv.ptr.compat + nr))
+ return ERR_PTR(-EFAULT);
+
+ return compat_ptr(compat);
+ }
+#endif
+
+ if (get_user(native, argv.ptr.native + nr))
+ return ERR_PTR(-EFAULT);
+
+ return native;
+}
+
+/*
+ * count() counts the number of strings in array ARGV.
+ */
+static int count(struct user_arg_ptr argv, int max)
+{
+ int i = 0;
+
+ if (argv.ptr.native != NULL) {
+ for (;;) {
+ const char __user *p = get_user_arg_ptr(argv, i);
+
+ if (!p)
+ break;
+
+ if (IS_ERR(p))
+ return -EFAULT;
+
+ if (i >= max)
+ return -E2BIG;
+ ++i;
+
+ if (fatal_signal_pending(current))
+ return -ERESTARTNOHAND;
+ cond_resched();
+ }
+ }
+ return i;
+}
+
+/*
+ * 'copy_strings()' copies argument/environment strings from the old
+ * processes's memory to the new process's stack. The call to get_user_pages()
+ * ensures the destination page is created and not swapped out.
+ */
+static int copy_strings(int argc, struct user_arg_ptr argv,
+ struct linux_binprm *bprm)
+{
+ struct page *kmapped_page = NULL;
+ char *kaddr = NULL;
+ unsigned long kpos = 0;
+ int ret;
+
+ while (argc-- > 0) {
+ const char __user *str;
+ int len;
+ unsigned long pos;
+
+ ret = -EFAULT;
+ str = get_user_arg_ptr(argv, argc);
+ if (IS_ERR(str))
+ goto out;
+
+ len = strnlen_user(str, MAX_ARG_STRLEN);
+ if (!len)
+ goto out;
+
+ ret = -E2BIG;
+ if (!valid_arg_len(bprm, len))
+ goto out;
+
+ /* We're going to work our way backwords. */
+ pos = bprm->p;
+ str += len;
+ bprm->p -= len;
+
+ while (len > 0) {
+ int offset, bytes_to_copy;
+
+ if (fatal_signal_pending(current)) {
+ ret = -ERESTARTNOHAND;
+ goto out;
+ }
+ cond_resched();
+
+ offset = pos % PAGE_SIZE;
+ if (offset == 0)
+ offset = PAGE_SIZE;
+
+ bytes_to_copy = offset;
+ if (bytes_to_copy > len)
+ bytes_to_copy = len;
+
+ offset -= bytes_to_copy;
+ pos -= bytes_to_copy;
+ str -= bytes_to_copy;
+ len -= bytes_to_copy;
+
+ if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
+ struct page *page;
+
+ page = get_arg_page(bprm, pos, 1);
+ if (!page) {
+ ret = -E2BIG;
+ goto out;
+ }
+
+ if (kmapped_page) {
+ flush_kernel_dcache_page(kmapped_page);
+ kunmap(kmapped_page);
+ put_arg_page(kmapped_page);
+ }
+ kmapped_page = page;
+ kaddr = kmap(kmapped_page);
+ kpos = pos & PAGE_MASK;
+ flush_arg_page(bprm, kpos, kmapped_page);
+ }
+ if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
+ ret = -EFAULT;
+ goto out;
+ }
+ }
+ }
+ ret = 0;
+out:
+ if (kmapped_page) {
+ flush_kernel_dcache_page(kmapped_page);
+ kunmap(kmapped_page);
+ put_arg_page(kmapped_page);
+ }
+ return ret;
+}
+
+/*
+ * Like copy_strings, but get argv and its values from kernel memory.
+ */
+int copy_strings_kernel(int argc, const char *const *__argv,
+ struct linux_binprm *bprm)
+{
+ int r;
+ mm_segment_t oldfs = get_fs();
+ struct user_arg_ptr argv = {
+ .ptr.native = (const char __user *const __user *)__argv,
+ };
+
+ set_fs(KERNEL_DS);
+ r = copy_strings(argc, argv, bprm);
+ set_fs(oldfs);
+
+ return r;
+}
+EXPORT_SYMBOL(copy_strings_kernel);
+
+#ifdef CONFIG_MMU
+
+/*
+ * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
+ * the binfmt code determines where the new stack should reside, we shift it to
+ * its final location. The process proceeds as follows:
+ *
+ * 1) Use shift to calculate the new vma endpoints.
+ * 2) Extend vma to cover both the old and new ranges. This ensures the
+ * arguments passed to subsequent functions are consistent.
+ * 3) Move vma's page tables to the new range.
+ * 4) Free up any cleared pgd range.
+ * 5) Shrink the vma to cover only the new range.
+ */
+static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ unsigned long old_start = vma->vm_start;
+ unsigned long old_end = vma->vm_end;
+ unsigned long length = old_end - old_start;
+ unsigned long new_start = old_start - shift;
+ unsigned long new_end = old_end - shift;
+ struct mmu_gather tlb;
+
+ BUG_ON(new_start > new_end);
+
+ /*
+ * ensure there are no vmas between where we want to go
+ * and where we are
+ */
+ if (vma != find_vma(mm, new_start))
+ return -EFAULT;
+
+ /*
+ * cover the whole range: [new_start, old_end)
+ */
+ if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
+ return -ENOMEM;
+
+ /*
+ * move the page tables downwards, on failure we rely on
+ * process cleanup to remove whatever mess we made.
+ */
+ if (length != move_page_tables(vma, old_start,
+ vma, new_start, length, false))
+ return -ENOMEM;
+
+ lru_add_drain();
+ tlb_gather_mmu(&tlb, mm, old_start, old_end);
+ if (new_end > old_start) {
+ /*
+ * when the old and new regions overlap clear from new_end.
+ */
+ free_pgd_range(&tlb, new_end, old_end, new_end,
+ vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
+ } else {
+ /*
+ * otherwise, clean from old_start; this is done to not touch
+ * the address space in [new_end, old_start) some architectures
+ * have constraints on va-space that make this illegal (IA64) -
+ * for the others its just a little faster.
+ */
+ free_pgd_range(&tlb, old_start, old_end, new_end,
+ vma->vm_next ? vma->vm_next->vm_start : USER_PGTABLES_CEILING);
+ }
+ tlb_finish_mmu(&tlb, old_start, old_end);
+
+ /*
+ * Shrink the vma to just the new range. Always succeeds.
+ */
+ vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
+
+ return 0;
+}
+
+/*
+ * Finalizes the stack vm_area_struct. The flags and permissions are updated,
+ * the stack is optionally relocated, and some extra space is added.
+ */
+int setup_arg_pages(struct linux_binprm *bprm,
+ unsigned long stack_top,
+ int executable_stack)
+{
+ unsigned long ret;
+ unsigned long stack_shift;
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma = bprm->vma;
+ struct vm_area_struct *prev = NULL;
+ unsigned long vm_flags;
+ unsigned long stack_base;
+ unsigned long stack_size;
+ unsigned long stack_expand;
+ unsigned long rlim_stack;
+
+#ifdef CONFIG_STACK_GROWSUP
+ /* Limit stack size */
+ stack_base = bprm->rlim_stack.rlim_max;
+ if (stack_base > STACK_SIZE_MAX)
+ stack_base = STACK_SIZE_MAX;
+
+ /* Add space for stack randomization. */
+ stack_base += (STACK_RND_MASK << PAGE_SHIFT);
+
+ /* Make sure we didn't let the argument array grow too large. */
+ if (vma->vm_end - vma->vm_start > stack_base)
+ return -ENOMEM;
+
+ stack_base = PAGE_ALIGN(stack_top - stack_base);
+
+ stack_shift = vma->vm_start - stack_base;
+ mm->arg_start = bprm->p - stack_shift;
+ bprm->p = vma->vm_end - stack_shift;
+#else
+ stack_top = arch_align_stack(stack_top);
+ stack_top = PAGE_ALIGN(stack_top);
+
+ if (unlikely(stack_top < mmap_min_addr) ||
+ unlikely(vma->vm_end - vma->vm_start >= stack_top - mmap_min_addr))
+ return -ENOMEM;
+
+ stack_shift = vma->vm_end - stack_top;
+
+ bprm->p -= stack_shift;
+ mm->arg_start = bprm->p;
+#endif
+
+ if (bprm->loader)
+ bprm->loader -= stack_shift;
+ bprm->exec -= stack_shift;
+
+ if (down_write_killable(&mm->mmap_sem))
+ return -EINTR;
+
+ vm_flags = VM_STACK_FLAGS;
+
+ /*
+ * Adjust stack execute permissions; explicitly enable for
+ * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
+ * (arch default) otherwise.
+ */
+ if (unlikely(executable_stack == EXSTACK_ENABLE_X))
+ vm_flags |= VM_EXEC;
+ 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);
+ if (ret)
+ goto out_unlock;
+ BUG_ON(prev != vma);
+
+ /* Move stack pages down in memory. */
+ if (stack_shift) {
+ ret = shift_arg_pages(vma, stack_shift);
+ if (ret)
+ 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;
+ /*
+ * Align this down to a page boundary as expand_stack
+ * will align it up.
+ */
+ rlim_stack = bprm->rlim_stack.rlim_cur & PAGE_MASK;
+#ifdef CONFIG_STACK_GROWSUP
+ if (stack_size + stack_expand > rlim_stack)
+ stack_base = vma->vm_start + rlim_stack;
+ else
+ stack_base = vma->vm_end + stack_expand;
+#else
+ if (stack_size + stack_expand > rlim_stack)
+ stack_base = vma->vm_end - rlim_stack;
+ else
+ stack_base = vma->vm_start - stack_expand;
+#endif
+ current->mm->start_stack = bprm->p;
+ ret = expand_stack(vma, stack_base);
+ if (ret)
+ ret = -EFAULT;
+
+out_unlock:
+ up_write(&mm->mmap_sem);
+ return ret;
+}
+EXPORT_SYMBOL(setup_arg_pages);
+
+#else
+
+/*
+ * Transfer the program arguments and environment from the holding pages
+ * onto the stack. The provided stack pointer is adjusted accordingly.
+ */
+int transfer_args_to_stack(struct linux_binprm *bprm,
+ unsigned long *sp_location)
+{
+ unsigned long index, stop, sp;
+ int ret = 0;
+
+ stop = bprm->p >> PAGE_SHIFT;
+ sp = *sp_location;
+
+ for (index = MAX_ARG_PAGES - 1; index >= stop; index--) {
+ unsigned int offset = index == stop ? bprm->p & ~PAGE_MASK : 0;
+ char *src = kmap(bprm->page[index]) + offset;
+ sp -= PAGE_SIZE - offset;
+ if (copy_to_user((void *) sp, src, PAGE_SIZE - offset) != 0)
+ ret = -EFAULT;
+ kunmap(bprm->page[index]);
+ if (ret)
+ goto out;
+ }
+
+ *sp_location = sp;
+
+out:
+ return ret;
+}
+EXPORT_SYMBOL(transfer_args_to_stack);
+
+#endif /* CONFIG_MMU */
+
+static struct file *do_open_execat(int fd, struct filename *name, int flags)
+{
+ struct file *file;
+ int err;
+ struct open_flags open_exec_flags = {
+ .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
+ .acc_mode = MAY_EXEC,
+ .intent = LOOKUP_OPEN,
+ .lookup_flags = LOOKUP_FOLLOW,
+ };
+
+ if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
+ return ERR_PTR(-EINVAL);
+ if (flags & AT_SYMLINK_NOFOLLOW)
+ open_exec_flags.lookup_flags &= ~LOOKUP_FOLLOW;
+ if (flags & AT_EMPTY_PATH)
+ open_exec_flags.lookup_flags |= LOOKUP_EMPTY;
+
+ file = do_filp_open(fd, name, &open_exec_flags);
+ if (IS_ERR(file))
+ goto out;
+
+ err = -EACCES;
+ if (!S_ISREG(file_inode(file)->i_mode))
+ goto exit;
+
+ if (path_noexec(&file->f_path))
+ goto exit;
+
+ err = deny_write_access(file);
+ if (err)
+ goto exit;
+
+ if (name->name[0] != '\0')
+ fsnotify_open(file);
+
+out:
+ return file;
+
+exit:
+ fput(file);
+ return ERR_PTR(err);
+}
+
+struct file *open_exec(const char *name)
+{
+ struct filename *filename = getname_kernel(name);
+ struct file *f = ERR_CAST(filename);
+
+ if (!IS_ERR(filename)) {
+ f = do_open_execat(AT_FDCWD, filename, 0);
+ putname(filename);
+ }
+ return f;
+}
+EXPORT_SYMBOL(open_exec);
+
+int kernel_read_file(struct file *file, void **buf, loff_t *size,
+ loff_t max_size, enum kernel_read_file_id id)
+{
+ loff_t i_size, pos;
+ ssize_t bytes = 0;
+ int ret;
+
+ if (!S_ISREG(file_inode(file)->i_mode) || max_size < 0)
+ return -EINVAL;
+
+ ret = deny_write_access(file);
+ if (ret)
+ return ret;
+
+ ret = security_kernel_read_file(file, id);
+ if (ret)
+ goto out;
+
+ i_size = i_size_read(file_inode(file));
+ if (max_size > 0 && i_size > max_size) {
+ ret = -EFBIG;
+ goto out;
+ }
+ if (i_size <= 0) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ if (id != READING_FIRMWARE_PREALLOC_BUFFER)
+ *buf = vmalloc(i_size);
+ if (!*buf) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ pos = 0;
+ while (pos < i_size) {
+ bytes = kernel_read(file, *buf + pos, i_size - pos, &pos);
+ if (bytes < 0) {
+ ret = bytes;
+ goto out;
+ }
+
+ if (bytes == 0)
+ break;
+ }
+
+ if (pos != i_size) {
+ ret = -EIO;
+ goto out_free;
+ }
+
+ ret = security_kernel_post_read_file(file, *buf, i_size, id);
+ if (!ret)
+ *size = pos;
+
+out_free:
+ if (ret < 0) {
+ if (id != READING_FIRMWARE_PREALLOC_BUFFER) {
+ vfree(*buf);
+ *buf = NULL;
+ }
+ }
+
+out:
+ allow_write_access(file);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(kernel_read_file);
+
+int kernel_read_file_from_path(const char *path, void **buf, loff_t *size,
+ loff_t max_size, enum kernel_read_file_id id)
+{
+ struct file *file;
+ int ret;
+
+ if (!path || !*path)
+ return -EINVAL;
+
+ file = filp_open(path, O_RDONLY, 0);
+ if (IS_ERR(file))
+ return PTR_ERR(file);
+
+ ret = kernel_read_file(file, buf, size, max_size, id);
+ fput(file);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(kernel_read_file_from_path);
+
+int kernel_read_file_from_fd(int fd, void **buf, loff_t *size, loff_t max_size,
+ enum kernel_read_file_id id)
+{
+ struct fd f = fdget(fd);
+ int ret = -EBADF;
+
+ if (!f.file)
+ goto out;
+
+ ret = kernel_read_file(f.file, buf, size, max_size, id);
+out:
+ fdput(f);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(kernel_read_file_from_fd);
+
+ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
+{
+ ssize_t res = vfs_read(file, (void __user *)addr, len, &pos);
+ if (res > 0)
+ flush_icache_range(addr, addr + len);
+ return res;
+}
+EXPORT_SYMBOL(read_code);
+
+static int exec_mmap(struct mm_struct *mm)
+{
+ struct task_struct *tsk;
+ struct mm_struct *old_mm, *active_mm;
+
+ /* Notify parent that we're no longer interested in the old VM */
+ tsk = current;
+ old_mm = current->mm;
+ mm_release(tsk, old_mm);
+
+ if (old_mm) {
+ sync_mm_rss(old_mm);
+ /*
+ * Make sure that if there is a core dump in progress
+ * for the old mm, we get out and die instead of going
+ * through with the exec. We must hold mmap_sem around
+ * checking core_state and changing tsk->mm.
+ */
+ down_read(&old_mm->mmap_sem);
+ if (unlikely(old_mm->core_state)) {
+ up_read(&old_mm->mmap_sem);
+ return -EINTR;
+ }
+ }
+ task_lock(tsk);
+ active_mm = tsk->active_mm;
+ tsk->mm = mm;
+ tsk->active_mm = mm;
+ activate_mm(active_mm, mm);
+ tsk->mm->vmacache_seqnum = 0;
+ vmacache_flush(tsk);
+ task_unlock(tsk);
+ if (old_mm) {
+ up_read(&old_mm->mmap_sem);
+ BUG_ON(active_mm != old_mm);
+ setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
+ mm_update_next_owner(old_mm);
+ mmput(old_mm);
+ return 0;
+ }
+ mmdrop(active_mm);
+ return 0;
+}
+
+/*
+ * This function makes sure the current process has its own signal table,
+ * so that flush_signal_handlers can later reset the handlers without
+ * disturbing other processes. (Other processes might share the signal
+ * table via the CLONE_SIGHAND option to clone().)
+ */
+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;
+
+ if (thread_group_empty(tsk))
+ goto no_thread_group;
+
+ /*
+ * Kill all other threads in the thread group.
+ */
+ spin_lock_irq(lock);
+ if (signal_group_exit(sig)) {
+ /*
+ * Another group action in progress, just
+ * return so that the signal is processed.
+ */
+ spin_unlock_irq(lock);
+ return -EAGAIN;
+ }
+
+ sig->group_exit_task = tsk;
+ sig->notify_count = zap_other_threads(tsk);
+ if (!thread_group_leader(tsk))
+ sig->notify_count--;
+
+ while (sig->notify_count) {
+ __set_current_state(TASK_KILLABLE);
+ spin_unlock_irq(lock);
+ schedule();
+ if (unlikely(__fatal_signal_pending(tsk)))
+ goto killed;
+ spin_lock_irq(lock);
+ }
+ spin_unlock_irq(lock);
+
+ /*
+ * At this point all other threads have exited, all we have to
+ * do is to wait for the thread group leader to become inactive,
+ * and to assume its PID:
+ */
+ if (!thread_group_leader(tsk)) {
+ struct task_struct *leader = tsk->group_leader;
+
+ for (;;) {
+ cgroup_threadgroup_change_begin(tsk);
+ write_lock_irq(&tasklist_lock);
+ /*
+ * Do this under tasklist_lock to ensure that
+ * exit_notify() can't miss ->group_exit_task
+ */
+ sig->notify_count = -1;
+ if (likely(leader->exit_state))
+ break;
+ __set_current_state(TASK_KILLABLE);
+ write_unlock_irq(&tasklist_lock);
+ cgroup_threadgroup_change_end(tsk);
+ schedule();
+ if (unlikely(__fatal_signal_pending(tsk)))
+ goto killed;
+ }
+
+ /*
+ * The only record we have of the real-time age of a
+ * process, regardless of execs it's done, is start_time.
+ * All the past CPU time is accumulated in signal_struct
+ * from sister threads now dead. But in this non-leader
+ * exec, nothing survives from the original leader thread,
+ * whose birth marks the true age of this process now.
+ * When we take on its identity by switching to its PID, we
+ * also take its birthdate (always earlier than our own).
+ */
+ tsk->start_time = leader->start_time;
+ tsk->real_start_time = leader->real_start_time;
+
+ BUG_ON(!same_thread_group(leader, tsk));
+ BUG_ON(has_group_leader_pid(tsk));
+ /*
+ * An exec() starts a new thread group with the
+ * TGID of the previous thread group. Rehash the
+ * two threads with a switched PID, and release
+ * the former thread group leader:
+ */
+
+ /* Become a process group leader with the old leader's pid.
+ * The old leader becomes a thread of the this thread group.
+ * Note: The old leader also uses this pid until release_task
+ * is called. Odd but simple and correct.
+ */
+ tsk->pid = leader->pid;
+ change_pid(tsk, PIDTYPE_PID, task_pid(leader));
+ transfer_pid(leader, tsk, PIDTYPE_TGID);
+ transfer_pid(leader, tsk, PIDTYPE_PGID);
+ transfer_pid(leader, tsk, PIDTYPE_SID);
+
+ list_replace_rcu(&leader->tasks, &tsk->tasks);
+ list_replace_init(&leader->sibling, &tsk->sibling);
+
+ tsk->group_leader = tsk;
+ leader->group_leader = tsk;
+
+ tsk->exit_signal = SIGCHLD;
+ leader->exit_signal = -1;
+
+ BUG_ON(leader->exit_state != EXIT_ZOMBIE);
+ leader->exit_state = EXIT_DEAD;
+
+ /*
+ * We are going to release_task()->ptrace_unlink() silently,
+ * the tracer can sleep in do_wait(). EXIT_DEAD guarantees
+ * the tracer wont't block again waiting for this thread.
+ */
+ if (unlikely(leader->ptrace))
+ __wake_up_parent(leader, leader->parent);
+ write_unlock_irq(&tasklist_lock);
+ cgroup_threadgroup_change_end(tsk);
+
+ release_task(leader);
+ }
+
+ sig->group_exit_task = NULL;
+ sig->notify_count = 0;
+
+no_thread_group:
+ /* we have changed execution domain */
+ tsk->exit_signal = SIGCHLD;
+
+#ifdef CONFIG_POSIX_TIMERS
+ exit_itimers(sig);
+ flush_itimer_signals();
+#endif
+
+ if (atomic_read(&oldsighand->count) != 1) {
+ struct sighand_struct *newsighand;
+ /*
+ * This ->sighand is shared with the CLONE_SIGHAND
+ * but not CLONE_THREAD task, switch to the new one.
+ */
+ newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
+ if (!newsighand)
+ return -ENOMEM;
+
+ atomic_set(&newsighand->count, 1);
+ memcpy(newsighand->action, oldsighand->action,
+ sizeof(newsighand->action));
+
+ write_lock_irq(&tasklist_lock);
+ spin_lock(&oldsighand->siglock);
+ rcu_assign_pointer(tsk->sighand, newsighand);
+ spin_unlock(&oldsighand->siglock);
+ write_unlock_irq(&tasklist_lock);
+
+ __cleanup_sighand(oldsighand);
+ }
+
+ BUG_ON(!thread_group_leader(tsk));
+ return 0;
+
+killed:
+ /* protects against exit_notify() and __exit_signal() */
+ read_lock(&tasklist_lock);
+ sig->group_exit_task = NULL;
+ sig->notify_count = 0;
+ read_unlock(&tasklist_lock);
+ return -EAGAIN;
+}
+
+char *__get_task_comm(char *buf, size_t buf_size, struct task_struct *tsk)
+{
+ task_lock(tsk);
+ strncpy(buf, tsk->comm, buf_size);
+ task_unlock(tsk);
+ return buf;
+}
+EXPORT_SYMBOL_GPL(__get_task_comm);
+
+/*
+ * These functions flushes out all traces of the currently running executable
+ * so that a new one can be started
+ */
+
+void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
+{
+ task_lock(tsk);
+ trace_task_rename(tsk, buf);
+ strlcpy(tsk->comm, buf, sizeof(tsk->comm));
+ task_unlock(tsk);
+ perf_event_comm(tsk, exec);
+}
+
+/*
+ * Calling this is the point of no return. None of the failures will be
+ * seen by userspace since either the process is already taking a fatal
+ * signal (via de_thread() or coredump), or will have SEGV raised
+ * (after exec_mmap()) by search_binary_handlers (see below).
+ */
+int flush_old_exec(struct linux_binprm * bprm)
+{
+ int retval;
+
+ /*
+ * Make sure we have a private signal table and that
+ * we are unassociated from the previous thread group.
+ */
+ retval = de_thread(current);
+ if (retval)
+ goto out;
+
+ /*
+ * Must be called _before_ exec_mmap() as bprm->mm is
+ * not visibile until then. This also enables the update
+ * to be lockless.
+ */
+ set_mm_exe_file(bprm->mm, bprm->file);
+
+ /*
+ * Release all of the old mmap stuff
+ */
+ acct_arg_size(bprm, 0);
+ retval = exec_mmap(bprm->mm);
+ if (retval)
+ goto out;
+
+ /*
+ * After clearing bprm->mm (to mark that current is using the
+ * prepared mm now), we have nothing left of the original
+ * process. If anything from here on returns an error, the check
+ * in search_binary_handler() will SEGV current.
+ */
+ bprm->mm = NULL;
+
+ set_fs(USER_DS);
+ current->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD |
+ PF_NOFREEZE | PF_NO_SETAFFINITY);
+ 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:
+ return retval;
+}
+EXPORT_SYMBOL(flush_old_exec);
+
+void would_dump(struct linux_binprm *bprm, struct file *file)
+{
+ 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);
+
+void setup_new_exec(struct linux_binprm * bprm)
+{
+ /*
+ * Once here, prepare_binrpm() will not be called any more, so
+ * the final state of setuid/setgid/fscaps can be merged into the
+ * secureexec flag.
+ */
+ bprm->secureexec |= bprm->cap_elevated;
+
+ if (bprm->secureexec) {
+ /* Make sure parent cannot signal privileged process. */
+ current->pdeath_signal = 0;
+
+ /*
+ * For secureexec, reset the stack limit to sane default to
+ * avoid bad behavior from the prior rlimits. This has to
+ * happen before arch_pick_mmap_layout(), which examines
+ * RLIMIT_STACK, but after the point of no return to avoid
+ * needing to clean up the change on failure.
+ */
+ if (bprm->rlim_stack.rlim_cur > _STK_LIM)
+ bprm->rlim_stack.rlim_cur = _STK_LIM;
+ }
+
+ arch_pick_mmap_layout(current->mm, &bprm->rlim_stack);
+
+ current->sas_ss_sp = current->sas_ss_size = 0;
+
+ /*
+ * Figure out dumpability. Note that this checking only of current
+ * is wrong, but userspace depends on it. This should be testing
+ * bprm->secureexec instead.
+ */
+ if (bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP ||
+ !(uid_eq(current_euid(), current_uid()) &&
+ gid_eq(current_egid(), current_gid())))
+ set_dumpable(current->mm, suid_dumpable);
+ else
+ set_dumpable(current->mm, SUID_DUMP_USER);
+
+ arch_setup_new_exec();
+ perf_event_exec();
+ __set_task_comm(current, kbasename(bprm->filename), true);
+
+ /* Set the new mm task size. We have to do that late because it may
+ * depend on TIF_32BIT which is only updated in flush_thread() on
+ * some architectures like powerpc
+ */
+ current->mm->task_size = TASK_SIZE;
+
+ /* An exec changes our domain. We are no longer part of the thread
+ group */
+ current->self_exec_id++;
+ flush_signal_handlers(current, 0);
+}
+EXPORT_SYMBOL(setup_new_exec);
+
+/* Runs immediately before start_thread() takes over. */
+void finalize_exec(struct linux_binprm *bprm)
+{
+ /* Store any stack rlimit changes before starting thread. */
+ task_lock(current->group_leader);
+ current->signal->rlim[RLIMIT_STACK] = bprm->rlim_stack;
+ task_unlock(current->group_leader);
+}
+EXPORT_SYMBOL(finalize_exec);
+
+/*
+ * Prepare credentials and lock ->cred_guard_mutex.
+ * install_exec_creds() commits the new creds and drops the lock.
+ * Or, if exec fails before, free_bprm() should release ->cred and
+ * and unlock.
+ */
+int prepare_bprm_creds(struct linux_binprm *bprm)
+{
+ if (mutex_lock_interruptible(¤t->signal->cred_guard_mutex))
+ return -ERESTARTNOINTR;
+
+ bprm->cred = prepare_exec_creds();
+ if (likely(bprm->cred))
+ return 0;
+
+ mutex_unlock(¤t->signal->cred_guard_mutex);
+ return -ENOMEM;
+}
+
+static void free_bprm(struct linux_binprm *bprm)
+{
+ free_arg_pages(bprm);
+ if (bprm->cred) {
+ mutex_unlock(¤t->signal->cred_guard_mutex);
+ abort_creds(bprm->cred);
+ }
+ if (bprm->file) {
+ allow_write_access(bprm->file);
+ fput(bprm->file);
+ }
+ /* If a binfmt changed the interp, free it. */
+ if (bprm->interp != bprm->filename)
+ kfree(bprm->interp);
+ kfree(bprm);
+}
+
+int bprm_change_interp(const char *interp, struct linux_binprm *bprm)
+{
+ /* If a binfmt changed the interp, free it first. */
+ if (bprm->interp != bprm->filename)
+ kfree(bprm->interp);
+ bprm->interp = kstrdup(interp, GFP_KERNEL);
+ if (!bprm->interp)
+ return -ENOMEM;
+ return 0;
+}
+EXPORT_SYMBOL(bprm_change_interp);
+
+/*
+ * install the new credentials for this executable
+ */
+void install_exec_creds(struct linux_binprm *bprm)
+{
+ security_bprm_committing_creds(bprm);
+
+ commit_creds(bprm->cred);
+ bprm->cred = NULL;
+
+ /*
+ * Disable monitoring for regular users
+ * when executing setuid binaries. Must
+ * wait until new credentials are committed
+ * by commit_creds() above
+ */
+ if (get_dumpable(current->mm) != SUID_DUMP_USER)
+ perf_event_exit_task(current);
+ /*
+ * cred_guard_mutex must be held at least to this point to prevent
+ * ptrace_attach() from altering our determination of the task's
+ * credentials; any time after this it may be unlocked.
+ */
+ security_bprm_committed_creds(bprm);
+ mutex_unlock(¤t->signal->cred_guard_mutex);
+}
+EXPORT_SYMBOL(install_exec_creds);
+
+/*
+ * determine how safe it is to execute the proposed program
+ * - the caller must hold ->cred_guard_mutex to protect against
+ * PTRACE_ATTACH or seccomp thread-sync
+ */
+static void check_unsafe_exec(struct linux_binprm *bprm)
+{
+ struct task_struct *p = current, *t;
+ unsigned n_fs;
+
+ if (p->ptrace)
+ bprm->unsafe |= LSM_UNSAFE_PTRACE;
+
+ /*
+ * This isn't strictly necessary, but it makes it harder for LSMs to
+ * mess up.
+ */
+ if (task_no_new_privs(current))
+ bprm->unsafe |= LSM_UNSAFE_NO_NEW_PRIVS;
+
+ t = p;
+ n_fs = 1;
+ spin_lock(&p->fs->lock);
+ rcu_read_lock();
+ while_each_thread(p, t) {
+ if (t->fs == p->fs)
+ n_fs++;
+ }
+ rcu_read_unlock();
+
+ if (p->fs->users > n_fs)
+ bprm->unsafe |= LSM_UNSAFE_SHARE;
+ else
+ p->fs->in_exec = 1;
+ spin_unlock(&p->fs->lock);
+}
+
+static void bprm_fill_uid(struct linux_binprm *bprm)
+{
+ struct inode *inode;
+ unsigned int mode;
+ kuid_t uid;
+ kgid_t gid;
+
+ /*
+ * Since this can be called multiple times (via prepare_binprm),
+ * we must clear any previous work done when setting set[ug]id
+ * bits from any earlier bprm->file uses (for example when run
+ * first for a setuid script then again for its interpreter).
+ */
+ bprm->cred->euid = current_euid();
+ bprm->cred->egid = current_egid();
+
+ if (!mnt_may_suid(bprm->file->f_path.mnt))
+ return;
+
+ if (task_no_new_privs(current))
+ return;
+
+ inode = bprm->file->f_path.dentry->d_inode;
+ mode = READ_ONCE(inode->i_mode);
+ if (!(mode & (S_ISUID|S_ISGID)))
+ return;
+
+ /* Be careful if suid/sgid is set */
+ inode_lock(inode);
+
+ /* reload atomically mode/uid/gid now that lock held */
+ mode = inode->i_mode;
+ uid = inode->i_uid;
+ gid = inode->i_gid;
+ inode_unlock(inode);
+
+ /* We ignore suid/sgid if there are no mappings for them in the ns */
+ if (!kuid_has_mapping(bprm->cred->user_ns, uid) ||
+ !kgid_has_mapping(bprm->cred->user_ns, gid))
+ return;
+
+ if (mode & S_ISUID) {
+ bprm->per_clear |= PER_CLEAR_ON_SETID;
+ bprm->cred->euid = uid;
+ }
+
+ if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
+ bprm->per_clear |= PER_CLEAR_ON_SETID;
+ bprm->cred->egid = gid;
+ }
+}
+
+/*
+ * Fill the binprm structure from the inode.
+ * Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
+ *
+ * This may be called multiple times for binary chains (scripts for example).
+ */
+int prepare_binprm(struct linux_binprm *bprm)
+{
+ int retval;
+ loff_t pos = 0;
+
+ bprm_fill_uid(bprm);
+
+ /* fill in binprm security blob */
+ retval = security_bprm_set_creds(bprm);
+ if (retval)
+ return retval;
+ bprm->called_set_creds = 1;
+
+ memset(bprm->buf, 0, BINPRM_BUF_SIZE);
+ return kernel_read(bprm->file, bprm->buf, BINPRM_BUF_SIZE, &pos);
+}
+
+EXPORT_SYMBOL(prepare_binprm);
+
+/*
+ * Arguments are '\0' separated strings found at the location bprm->p
+ * points to; chop off the first by relocating brpm->p to right after
+ * the first '\0' encountered.
+ */
+int remove_arg_zero(struct linux_binprm *bprm)
+{
+ int ret = 0;
+ unsigned long offset;
+ char *kaddr;
+ struct page *page;
+
+ if (!bprm->argc)
+ return 0;
+
+ do {
+ offset = bprm->p & ~PAGE_MASK;
+ page = get_arg_page(bprm, bprm->p, 0);
+ if (!page) {
+ ret = -EFAULT;
+ goto out;
+ }
+ kaddr = kmap_atomic(page);
+
+ for (; offset < PAGE_SIZE && kaddr[offset];
+ offset++, bprm->p++)
+ ;
+
+ kunmap_atomic(kaddr);
+ put_arg_page(page);
+ } while (offset == PAGE_SIZE);
+
+ bprm->p++;
+ bprm->argc--;
+ ret = 0;
+
+out:
+ return ret;
+}
+EXPORT_SYMBOL(remove_arg_zero);
+
+#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
+/*
+ * cycle the list of binary formats handler, until one recognizes the image
+ */
+int search_binary_handler(struct linux_binprm *bprm)
+{
+ bool need_retry = IS_ENABLED(CONFIG_MODULES);
+ struct linux_binfmt *fmt;
+ int retval;
+
+ /* This allows 4 levels of binfmt rewrites before failing hard. */
+ if (bprm->recursion_depth > 5)
+ return -ELOOP;
+
+ retval = security_bprm_check(bprm);
+ if (retval)
+ return retval;
+
+ retval = -ENOENT;
+ retry:
+ read_lock(&binfmt_lock);
+ list_for_each_entry(fmt, &formats, lh) {
+ if (!try_module_get(fmt->module))
+ continue;
+ read_unlock(&binfmt_lock);
+ bprm->recursion_depth++;
+ retval = fmt->load_binary(bprm);
+ read_lock(&binfmt_lock);
+ put_binfmt(fmt);
+ bprm->recursion_depth--;
+ if (retval < 0 && !bprm->mm) {
+ /* we got to flush_old_exec() and failed after it */
+ read_unlock(&binfmt_lock);
+ force_sigsegv(SIGSEGV, current);
+ return retval;
+ }
+ if (retval != -ENOEXEC || !bprm->file) {
+ read_unlock(&binfmt_lock);
+ return retval;
+ }
+ }
+ read_unlock(&binfmt_lock);
+
+ if (need_retry) {
+ if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
+ printable(bprm->buf[2]) && printable(bprm->buf[3]))
+ return retval;
+ if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
+ return retval;
+ need_retry = false;
+ goto retry;
+ }
+
+ return retval;
+}
+EXPORT_SYMBOL(search_binary_handler);
+
+static int exec_binprm(struct linux_binprm *bprm)
+{
+ pid_t old_pid, old_vpid;
+ int ret;
+
+ /* Need to fetch pid before load_binary changes it */
+ old_pid = current->pid;
+ rcu_read_lock();
+ old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
+ rcu_read_unlock();
+
+ ret = search_binary_handler(bprm);
+ if (ret >= 0) {
+ audit_bprm(bprm);
+ trace_sched_process_exec(current, old_pid, bprm);
+ ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
+ proc_exec_connector(current);
+ }
+
+ return ret;
+}
+
+/*
+ * sys_execve() executes a new program.
+ */
+static int __do_execve_file(int fd, struct filename *filename,
+ struct user_arg_ptr argv,
+ struct user_arg_ptr envp,
+ int flags, struct file *file)
+{
+ char *pathbuf = NULL;
+ struct linux_binprm *bprm;
+ struct files_struct *displaced;
+ int retval;
+
+ if (IS_ERR(filename))
+ return PTR_ERR(filename);
+
+ /*
+ * We move the actual failure in case of RLIMIT_NPROC excess from
+ * set*uid() to execve() because too many poorly written programs
+ * don't check setuid() return code. Here we additionally recheck
+ * whether NPROC limit is still exceeded.
+ */
+ if ((current->flags & PF_NPROC_EXCEEDED) &&
+ atomic_read(¤t_user()->processes) > rlimit(RLIMIT_NPROC)) {
+ retval = -EAGAIN;
+ goto out_ret;
+ }
+
+ /* We're below the limit (still or again), so we don't want to make
+ * further execve() calls fail. */
+ current->flags &= ~PF_NPROC_EXCEEDED;
+
+ retval = unshare_files(&displaced);
+ if (retval)
+ goto out_ret;
+
+ retval = -ENOMEM;
+ bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
+ if (!bprm)
+ goto out_files;
+
+ retval = prepare_bprm_creds(bprm);
+ if (retval)
+ goto out_free;
+
+ check_unsafe_exec(bprm);
+ current->in_execve = 1;
+
+ if (!file)
+ file = do_open_execat(fd, filename, flags);
+ retval = PTR_ERR(file);
+ if (IS_ERR(file))
+ goto out_unmark;
+
+ sched_exec();
+
+ bprm->file = file;
+ if (!filename) {
+ bprm->filename = "none";
+ } else if (fd == AT_FDCWD || filename->name[0] == '/') {
+ bprm->filename = filename->name;
+ } else {
+ if (filename->name[0] == '\0')
+ pathbuf = kasprintf(GFP_KERNEL, "/dev/fd/%d", fd);
+ else
+ pathbuf = kasprintf(GFP_KERNEL, "/dev/fd/%d/%s",
+ fd, filename->name);
+ if (!pathbuf) {
+ retval = -ENOMEM;
+ goto out_unmark;
+ }
+ /*
+ * Record that a name derived from an O_CLOEXEC fd will be
+ * inaccessible after exec. Relies on having exclusive access to
+ * current->files (due to unshare_files above).
+ */
+ if (close_on_exec(fd, rcu_dereference_raw(current->files->fdt)))
+ bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE;
+ bprm->filename = pathbuf;
+ }
+ bprm->interp = bprm->filename;
+
+ retval = bprm_mm_init(bprm);
+ if (retval)
+ goto out_unmark;
+
+ bprm->argc = count(argv, MAX_ARG_STRINGS);
+ if ((retval = bprm->argc) < 0)
+ goto out;
+
+ bprm->envc = count(envp, MAX_ARG_STRINGS);
+ if ((retval = bprm->envc) < 0)
+ goto out;
+
+ retval = prepare_binprm(bprm);
+ if (retval < 0)
+ goto out;
+
+ retval = copy_strings_kernel(1, &bprm->filename, bprm);
+ if (retval < 0)
+ goto out;
+
+ bprm->exec = bprm->p;
+ retval = copy_strings(bprm->envc, envp, bprm);
+ if (retval < 0)
+ goto out;
+
+ retval = copy_strings(bprm->argc, argv, bprm);
+ if (retval < 0)
+ goto out;
+
+ would_dump(bprm, bprm->file);
+
+ retval = exec_binprm(bprm);
+ if (retval < 0)
+ goto out;
+
+ /* execve succeeded */
+ current->fs->in_exec = 0;
+ current->in_execve = 0;
+ membarrier_execve(current);
+ rseq_execve(current);
+ acct_update_integrals(current);
+ task_numa_free(current);
+ free_bprm(bprm);
+ kfree(pathbuf);
+ if (filename)
+ putname(filename);
+ if (displaced)
+ put_files_struct(displaced);
+ return retval;
+
+out:
+ if (bprm->mm) {
+ acct_arg_size(bprm, 0);
+ mmput(bprm->mm);
+ }
+
+out_unmark:
+ current->fs->in_exec = 0;
+ current->in_execve = 0;
+
+out_free:
+ free_bprm(bprm);
+ kfree(pathbuf);
+
+out_files:
+ if (displaced)
+ reset_files_struct(displaced);
+out_ret:
+ if (filename)
+ putname(filename);
+ return retval;
+}
+
+static int do_execveat_common(int fd, struct filename *filename,
+ struct user_arg_ptr argv,
+ struct user_arg_ptr envp,
+ int flags)
+{
+ return __do_execve_file(fd, filename, argv, envp, flags, NULL);
+}
+
+int do_execve_file(struct file *file, void *__argv, void *__envp)
+{
+ struct user_arg_ptr argv = { .ptr.native = __argv };
+ struct user_arg_ptr envp = { .ptr.native = __envp };
+
+ return __do_execve_file(AT_FDCWD, NULL, argv, envp, 0, file);
+}
+
+int do_execve(struct filename *filename,
+ const char __user *const __user *__argv,
+ const char __user *const __user *__envp)
+{
+ struct user_arg_ptr argv = { .ptr.native = __argv };
+ struct user_arg_ptr envp = { .ptr.native = __envp };
+ return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
+}
+
+int do_execveat(int fd, struct filename *filename,
+ const char __user *const __user *__argv,
+ const char __user *const __user *__envp,
+ int flags)
+{
+ struct user_arg_ptr argv = { .ptr.native = __argv };
+ struct user_arg_ptr envp = { .ptr.native = __envp };
+
+ return do_execveat_common(fd, filename, argv, envp, flags);
+}
+
+#ifdef CONFIG_COMPAT
+static int compat_do_execve(struct filename *filename,
+ const compat_uptr_t __user *__argv,
+ const compat_uptr_t __user *__envp)
+{
+ struct user_arg_ptr argv = {
+ .is_compat = true,
+ .ptr.compat = __argv,
+ };
+ struct user_arg_ptr envp = {
+ .is_compat = true,
+ .ptr.compat = __envp,
+ };
+ return do_execveat_common(AT_FDCWD, filename, argv, envp, 0);
+}
+
+static int compat_do_execveat(int fd, struct filename *filename,
+ const compat_uptr_t __user *__argv,
+ const compat_uptr_t __user *__envp,
+ int flags)
+{
+ struct user_arg_ptr argv = {
+ .is_compat = true,
+ .ptr.compat = __argv,
+ };
+ struct user_arg_ptr envp = {
+ .is_compat = true,
+ .ptr.compat = __envp,
+ };
+ return do_execveat_common(fd, filename, argv, envp, flags);
+}
+#endif
+
+void set_binfmt(struct linux_binfmt *new)
+{
+ struct mm_struct *mm = current->mm;
+
+ if (mm->binfmt)
+ module_put(mm->binfmt->module);
+
+ mm->binfmt = new;
+ if (new)
+ __module_get(new->module);
+}
+EXPORT_SYMBOL(set_binfmt);
+
+/*
+ * set_dumpable stores three-value SUID_DUMP_* into mm->flags.
+ */
+void set_dumpable(struct mm_struct *mm, int value)
+{
+ unsigned long old, new;
+
+ if (WARN_ON((unsigned)value > SUID_DUMP_ROOT))
+ return;
+
+ do {
+ old = READ_ONCE(mm->flags);
+ new = (old & ~MMF_DUMPABLE_MASK) | value;
+ } while (cmpxchg(&mm->flags, old, new) != old);
+}
+
+SYSCALL_DEFINE3(execve,
+ const char __user *, filename,
+ const char __user *const __user *, argv,
+ const char __user *const __user *, envp)
+{
+ return do_execve(getname(filename), argv, envp);
+}
+
+SYSCALL_DEFINE5(execveat,
+ int, fd, const char __user *, filename,
+ const char __user *const __user *, argv,
+ const char __user *const __user *, envp,
+ int, flags)
+{
+ int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
+
+ return do_execveat(fd,
+ getname_flags(filename, lookup_flags, NULL),
+ argv, envp, flags);
+}
+
+#ifdef CONFIG_COMPAT
+COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename,
+ const compat_uptr_t __user *, argv,
+ const compat_uptr_t __user *, envp)
+{
+ return compat_do_execve(getname(filename), argv, envp);
+}
+
+COMPAT_SYSCALL_DEFINE5(execveat, int, fd,
+ const char __user *, filename,
+ const compat_uptr_t __user *, argv,
+ const compat_uptr_t __user *, envp,
+ int, flags)
+{
+ int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
+
+ return compat_do_execveat(fd,
+ getname_flags(filename, lookup_flags, NULL),
+ argv, envp, flags);
+}
+#endif