linux/fs/exec.c

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/*
* 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/config.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/mman.h>
#include <linux/a.out.h>
#include <linux/stat.h>
#include <linux/fcntl.h>
#include <linux/smp_lock.h>
#include <linux/init.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <linux/spinlock.h>
#include <linux/key.h>
#include <linux/personality.h>
#include <linux/binfmts.h>
#include <linux/swap.h>
#include <linux/utsname.h>
#include <linux/module.h>
#include <linux/namei.h>
#include <linux/proc_fs.h>
#include <linux/ptrace.h>
#include <linux/mount.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/rmap.h>
#include <linux/acct.h>
#include <linux/cn_proc.h>
#include <asm/uaccess.h>
#include <asm/mmu_context.h>
#ifdef CONFIG_KMOD
#include <linux/kmod.h>
#endif
int core_uses_pid;
char core_pattern[65] = "core";
[PATCH] setuid core dump Add a new `suid_dumpable' sysctl: This value can be used to query and set the core dump mode for setuid or otherwise protected/tainted binaries. The modes are 0 - (default) - traditional behaviour. Any process which has changed privilege levels or is execute only will not be dumped 1 - (debug) - all processes dump core when possible. The core dump is owned by the current user and no security is applied. This is intended for system debugging situations only. Ptrace is unchecked. 2 - (suidsafe) - any binary which normally would not be dumped is dumped readable by root only. This allows the end user to remove such a dump but not access it directly. For security reasons core dumps in this mode will not overwrite one another or other files. This mode is appropriate when adminstrators are attempting to debug problems in a normal environment. (akpm: > > +EXPORT_SYMBOL(suid_dumpable); > > EXPORT_SYMBOL_GPL? No problem to me. > > if (current->euid == current->uid && current->egid == current->gid) > > current->mm->dumpable = 1; > > Should this be SUID_DUMP_USER? Actually the feedback I had from last time was that the SUID_ defines should go because its clearer to follow the numbers. They can go everywhere (and there are lots of places where dumpable is tested/used as a bool in untouched code) > Maybe this should be renamed to `dump_policy' or something. Doing that > would help us catch any code which isn't using the #defines, too. Fair comment. The patch was designed to be easy to maintain for Red Hat rather than for merging. Changing that field would create a gigantic diff because it is used all over the place. ) Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:43 +00:00
int suid_dumpable = 0;
EXPORT_SYMBOL(suid_dumpable);
/* The maximal length of core_pattern is also specified in sysctl.c */
static struct linux_binfmt *formats;
static DEFINE_RWLOCK(binfmt_lock);
int register_binfmt(struct linux_binfmt * fmt)
{
struct linux_binfmt ** tmp = &formats;
if (!fmt)
return -EINVAL;
if (fmt->next)
return -EBUSY;
write_lock(&binfmt_lock);
while (*tmp) {
if (fmt == *tmp) {
write_unlock(&binfmt_lock);
return -EBUSY;
}
tmp = &(*tmp)->next;
}
fmt->next = formats;
formats = fmt;
write_unlock(&binfmt_lock);
return 0;
}
EXPORT_SYMBOL(register_binfmt);
int unregister_binfmt(struct linux_binfmt * fmt)
{
struct linux_binfmt ** tmp = &formats;
write_lock(&binfmt_lock);
while (*tmp) {
if (fmt == *tmp) {
*tmp = fmt->next;
write_unlock(&binfmt_lock);
return 0;
}
tmp = &(*tmp)->next;
}
write_unlock(&binfmt_lock);
return -EINVAL;
}
EXPORT_SYMBOL(unregister_binfmt);
static inline void put_binfmt(struct linux_binfmt * fmt)
{
module_put(fmt->module);
}
/*
* 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.
*/
asmlinkage long sys_uselib(const char __user * library)
{
struct file * file;
struct nameidata nd;
int error;
error = __user_path_lookup_open(library, LOOKUP_FOLLOW, &nd, FMODE_READ);
if (error)
goto out;
error = -EINVAL;
if (!S_ISREG(nd.dentry->d_inode->i_mode))
goto exit;
error = vfs_permission(&nd, MAY_READ | MAY_EXEC);
if (error)
goto exit;
file = nameidata_to_filp(&nd, O_RDONLY);
error = PTR_ERR(file);
if (IS_ERR(file))
goto out;
error = -ENOEXEC;
if(file->f_op) {
struct linux_binfmt * fmt;
read_lock(&binfmt_lock);
for (fmt = formats ; fmt ; fmt = fmt->next) {
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);
}
fput(file);
out:
return error;
exit:
release_open_intent(&nd);
path_release(&nd);
goto out;
}
/*
* count() counts the number of strings in array ARGV.
*/
static int count(char __user * __user * argv, int max)
{
int i = 0;
if (argv != NULL) {
for (;;) {
char __user * p;
if (get_user(p, argv))
return -EFAULT;
if (!p)
break;
argv++;
if(++i > max)
return -E2BIG;
cond_resched();
}
}
return i;
}
/*
* 'copy_strings()' copies argument/environment strings from user
* memory to free pages in kernel mem. These are in a format ready
* to be put directly into the top of new user memory.
*/
static int copy_strings(int argc, char __user * __user * argv,
struct linux_binprm *bprm)
{
struct page *kmapped_page = NULL;
char *kaddr = NULL;
int ret;
while (argc-- > 0) {
char __user *str;
int len;
unsigned long pos;
if (get_user(str, argv+argc) ||
!(len = strnlen_user(str, bprm->p))) {
ret = -EFAULT;
goto out;
}
if (bprm->p < len) {
ret = -E2BIG;
goto out;
}
bprm->p -= len;
/* XXX: add architecture specific overflow check here. */
pos = bprm->p;
while (len > 0) {
int i, new, err;
int offset, bytes_to_copy;
struct page *page;
offset = pos % PAGE_SIZE;
i = pos/PAGE_SIZE;
page = bprm->page[i];
new = 0;
if (!page) {
page = alloc_page(GFP_HIGHUSER);
bprm->page[i] = page;
if (!page) {
ret = -ENOMEM;
goto out;
}
new = 1;
}
if (page != kmapped_page) {
if (kmapped_page)
kunmap(kmapped_page);
kmapped_page = page;
kaddr = kmap(kmapped_page);
}
if (new && offset)
memset(kaddr, 0, offset);
bytes_to_copy = PAGE_SIZE - offset;
if (bytes_to_copy > len) {
bytes_to_copy = len;
if (new)
memset(kaddr+offset+len, 0,
PAGE_SIZE-offset-len);
}
err = copy_from_user(kaddr+offset, str, bytes_to_copy);
if (err) {
ret = -EFAULT;
goto out;
}
pos += bytes_to_copy;
str += bytes_to_copy;
len -= bytes_to_copy;
}
}
ret = 0;
out:
if (kmapped_page)
kunmap(kmapped_page);
return ret;
}
/*
* Like copy_strings, but get argv and its values from kernel memory.
*/
int copy_strings_kernel(int argc,char ** argv, struct linux_binprm *bprm)
{
int r;
mm_segment_t oldfs = get_fs();
set_fs(KERNEL_DS);
r = copy_strings(argc, (char __user * __user *)argv, bprm);
set_fs(oldfs);
return r;
}
EXPORT_SYMBOL(copy_strings_kernel);
#ifdef CONFIG_MMU
/*
* This routine is used to map in a page into an address space: needed by
* execve() for the initial stack and environment pages.
*
* vma->vm_mm->mmap_sem is held for writing.
*/
void install_arg_page(struct vm_area_struct *vma,
struct page *page, unsigned long address)
{
struct mm_struct *mm = vma->vm_mm;
pte_t * pte;
spinlock_t *ptl;
if (unlikely(anon_vma_prepare(vma)))
goto out;
flush_dcache_page(page);
pte = get_locked_pte(mm, address, &ptl);
if (!pte)
goto out;
if (!pte_none(*pte)) {
pte_unmap_unlock(pte, ptl);
goto out;
}
inc_mm_counter(mm, anon_rss);
lru_cache_add_active(page);
set_pte_at(mm, address, pte, pte_mkdirty(pte_mkwrite(mk_pte(
page, vma->vm_page_prot))));
page_add_new_anon_rmap(page, vma, address);
pte_unmap_unlock(pte, ptl);
/* no need for flush_tlb */
return;
out:
__free_page(page);
force_sig(SIGKILL, current);
}
#define EXTRA_STACK_VM_PAGES 20 /* random */
int setup_arg_pages(struct linux_binprm *bprm,
unsigned long stack_top,
int executable_stack)
{
unsigned long stack_base;
struct vm_area_struct *mpnt;
struct mm_struct *mm = current->mm;
int i, ret;
long arg_size;
#ifdef CONFIG_STACK_GROWSUP
/* Move the argument and environment strings to the bottom of the
* stack space.
*/
int offset, j;
char *to, *from;
/* Start by shifting all the pages down */
i = 0;
for (j = 0; j < MAX_ARG_PAGES; j++) {
struct page *page = bprm->page[j];
if (!page)
continue;
bprm->page[i++] = page;
}
/* Now move them within their pages */
offset = bprm->p % PAGE_SIZE;
to = kmap(bprm->page[0]);
for (j = 1; j < i; j++) {
memmove(to, to + offset, PAGE_SIZE - offset);
from = kmap(bprm->page[j]);
memcpy(to + PAGE_SIZE - offset, from, offset);
kunmap(bprm->page[j - 1]);
to = from;
}
memmove(to, to + offset, PAGE_SIZE - offset);
kunmap(bprm->page[j - 1]);
/* Limit stack size to 1GB */
stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
if (stack_base > (1 << 30))
stack_base = 1 << 30;
stack_base = PAGE_ALIGN(stack_top - stack_base);
/* Adjust bprm->p to point to the end of the strings. */
bprm->p = stack_base + PAGE_SIZE * i - offset;
mm->arg_start = stack_base;
arg_size = i << PAGE_SHIFT;
/* zero pages that were copied above */
while (i < MAX_ARG_PAGES)
bprm->page[i++] = NULL;
#else
stack_base = arch_align_stack(stack_top - MAX_ARG_PAGES*PAGE_SIZE);
stack_base = PAGE_ALIGN(stack_base);
bprm->p += stack_base;
mm->arg_start = bprm->p;
arg_size = stack_top - (PAGE_MASK & (unsigned long) mm->arg_start);
#endif
arg_size += EXTRA_STACK_VM_PAGES * PAGE_SIZE;
if (bprm->loader)
bprm->loader += stack_base;
bprm->exec += stack_base;
mpnt = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
if (!mpnt)
return -ENOMEM;
memset(mpnt, 0, sizeof(*mpnt));
down_write(&mm->mmap_sem);
{
mpnt->vm_mm = mm;
#ifdef CONFIG_STACK_GROWSUP
mpnt->vm_start = stack_base;
mpnt->vm_end = stack_base + arg_size;
#else
mpnt->vm_end = stack_top;
mpnt->vm_start = mpnt->vm_end - arg_size;
#endif
/* 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))
mpnt->vm_flags = VM_STACK_FLAGS | VM_EXEC;
else if (executable_stack == EXSTACK_DISABLE_X)
mpnt->vm_flags = VM_STACK_FLAGS & ~VM_EXEC;
else
mpnt->vm_flags = VM_STACK_FLAGS;
mpnt->vm_flags |= mm->def_flags;
mpnt->vm_page_prot = protection_map[mpnt->vm_flags & 0x7];
if ((ret = insert_vm_struct(mm, mpnt))) {
up_write(&mm->mmap_sem);
kmem_cache_free(vm_area_cachep, mpnt);
return ret;
}
mm->stack_vm = mm->total_vm = vma_pages(mpnt);
}
for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
struct page *page = bprm->page[i];
if (page) {
bprm->page[i] = NULL;
install_arg_page(mpnt, page, stack_base);
}
stack_base += PAGE_SIZE;
}
up_write(&mm->mmap_sem);
return 0;
}
EXPORT_SYMBOL(setup_arg_pages);
#define free_arg_pages(bprm) do { } while (0)
#else
static inline void free_arg_pages(struct linux_binprm *bprm)
{
int i;
for (i = 0; i < MAX_ARG_PAGES; i++) {
if (bprm->page[i])
__free_page(bprm->page[i]);
bprm->page[i] = NULL;
}
}
#endif /* CONFIG_MMU */
struct file *open_exec(const char *name)
{
struct nameidata nd;
int err;
struct file *file;
err = path_lookup_open(name, LOOKUP_FOLLOW, &nd, FMODE_READ);
file = ERR_PTR(err);
if (!err) {
struct inode *inode = nd.dentry->d_inode;
file = ERR_PTR(-EACCES);
if (!(nd.mnt->mnt_flags & MNT_NOEXEC) &&
S_ISREG(inode->i_mode)) {
int err = vfs_permission(&nd, MAY_EXEC);
if (!err && !(inode->i_mode & 0111))
err = -EACCES;
file = ERR_PTR(err);
if (!err) {
file = nameidata_to_filp(&nd, O_RDONLY);
if (!IS_ERR(file)) {
err = deny_write_access(file);
if (err) {
fput(file);
file = ERR_PTR(err);
}
}
out:
return file;
}
}
release_open_intent(&nd);
path_release(&nd);
}
goto out;
}
EXPORT_SYMBOL(open_exec);
int kernel_read(struct file *file, unsigned long offset,
char *addr, unsigned long count)
{
mm_segment_t old_fs;
loff_t pos = offset;
int result;
old_fs = get_fs();
set_fs(get_ds());
/* The cast to a user pointer is valid due to the set_fs() */
result = vfs_read(file, (void __user *)addr, count, &pos);
set_fs(old_fs);
return result;
}
EXPORT_SYMBOL(kernel_read);
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) {
/*
* 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_waiters and changing tsk->mm. The
* core-inducing thread will increment core_waiters for
* each thread whose ->mm == old_mm.
*/
down_read(&old_mm->mmap_sem);
if (unlikely(old_mm->core_waiters)) {
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);
task_unlock(tsk);
arch_pick_mmap_layout(mm);
if (old_mm) {
up_read(&old_mm->mmap_sem);
if (active_mm != old_mm) BUG();
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 inline int de_thread(struct task_struct *tsk)
{
struct signal_struct *sig = tsk->signal;
struct sighand_struct *newsighand, *oldsighand = tsk->sighand;
spinlock_t *lock = &oldsighand->siglock;
struct task_struct *leader = NULL;
int count;
/*
* If we don't share sighandlers, then we aren't sharing anything
* and we can just re-use it all.
*/
if (atomic_read(&oldsighand->count) <= 1) {
BUG_ON(atomic_read(&sig->count) != 1);
exit_itimers(sig);
return 0;
}
newsighand = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
if (!newsighand)
return -ENOMEM;
if (thread_group_empty(current))
goto no_thread_group;
/*
* Kill all other threads in the thread group.
* We must hold tasklist_lock to call zap_other_threads.
*/
read_lock(&tasklist_lock);
spin_lock_irq(lock);
if (sig->flags & SIGNAL_GROUP_EXIT) {
/*
* Another group action in progress, just
* return so that the signal is processed.
*/
spin_unlock_irq(lock);
read_unlock(&tasklist_lock);
kmem_cache_free(sighand_cachep, newsighand);
return -EAGAIN;
}
zap_other_threads(current);
read_unlock(&tasklist_lock);
/*
* Account for the thread group leader hanging around:
*/
count = 1;
if (!thread_group_leader(current)) {
count = 2;
/*
* The SIGALRM timer survives the exec, but needs to point
* at us as the new group leader now. We have a race with
* a timer firing now getting the old leader, so we need to
* synchronize with any firing (by calling del_timer_sync)
* before we can safely let the old group leader die.
*/
sig->real_timer.data = (unsigned long)current;
spin_unlock_irq(lock);
if (del_timer_sync(&sig->real_timer))
add_timer(&sig->real_timer);
spin_lock_irq(lock);
}
while (atomic_read(&sig->count) > count) {
sig->group_exit_task = current;
sig->notify_count = count;
__set_current_state(TASK_UNINTERRUPTIBLE);
spin_unlock_irq(lock);
schedule();
spin_lock_irq(lock);
}
sig->group_exit_task = NULL;
sig->notify_count = 0;
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(current)) {
struct task_struct *parent;
struct dentry *proc_dentry1, *proc_dentry2;
unsigned long ptrace;
/*
* Wait for the thread group leader to be a zombie.
* It should already be zombie at this point, most
* of the time.
*/
leader = current->group_leader;
while (leader->exit_state != EXIT_ZOMBIE)
yield();
spin_lock(&leader->proc_lock);
spin_lock(&current->proc_lock);
proc_dentry1 = proc_pid_unhash(current);
proc_dentry2 = proc_pid_unhash(leader);
write_lock_irq(&tasklist_lock);
BUG_ON(leader->tgid != current->tgid);
BUG_ON(current->pid == current->tgid);
/*
* 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:
*/
ptrace = leader->ptrace;
parent = leader->parent;
if (unlikely(ptrace) && unlikely(parent == current)) {
/*
* Joker was ptracing his own group leader,
* and now he wants to be his own parent!
* We can't have that.
*/
ptrace = 0;
}
ptrace_unlink(current);
ptrace_unlink(leader);
remove_parent(current);
remove_parent(leader);
switch_exec_pids(leader, current);
current->parent = current->real_parent = leader->real_parent;
leader->parent = leader->real_parent = child_reaper;
current->group_leader = current;
leader->group_leader = leader;
add_parent(current, current->parent);
add_parent(leader, leader->parent);
if (ptrace) {
current->ptrace = ptrace;
__ptrace_link(current, parent);
}
list_del(&current->tasks);
list_add_tail(&current->tasks, &init_task.tasks);
current->exit_signal = SIGCHLD;
BUG_ON(leader->exit_state != EXIT_ZOMBIE);
leader->exit_state = EXIT_DEAD;
write_unlock_irq(&tasklist_lock);
spin_unlock(&leader->proc_lock);
spin_unlock(&current->proc_lock);
proc_pid_flush(proc_dentry1);
proc_pid_flush(proc_dentry2);
}
/*
* There may be one thread left which is just exiting,
* but it's safe to stop telling the group to kill themselves.
*/
sig->flags = 0;
no_thread_group:
exit_itimers(sig);
if (leader)
release_task(leader);
BUG_ON(atomic_read(&sig->count) != 1);
if (atomic_read(&oldsighand->count) == 1) {
/*
* Now that we nuked the rest of the thread group,
* it turns out we are not sharing sighand any more either.
* So we can just keep it.
*/
kmem_cache_free(sighand_cachep, newsighand);
} else {
/*
* Move our state over to newsighand and switch it in.
*/
spin_lock_init(&newsighand->siglock);
atomic_set(&newsighand->count, 1);
memcpy(newsighand->action, oldsighand->action,
sizeof(newsighand->action));
write_lock_irq(&tasklist_lock);
spin_lock(&oldsighand->siglock);
spin_lock(&newsighand->siglock);
rcu_assign_pointer(current->sighand, newsighand);
recalc_sigpending();
spin_unlock(&newsighand->siglock);
spin_unlock(&oldsighand->siglock);
write_unlock_irq(&tasklist_lock);
if (atomic_dec_and_test(&oldsighand->count))
sighand_free(oldsighand);
}
BUG_ON(!thread_group_leader(current));
return 0;
}
/*
* These functions flushes out all traces of the currently running executable
* so that a new one can be started
*/
static inline void flush_old_files(struct files_struct * files)
{
long j = -1;
struct fdtable *fdt;
spin_lock(&files->file_lock);
for (;;) {
unsigned long set, i;
j++;
i = j * __NFDBITS;
fdt = files_fdtable(files);
if (i >= fdt->max_fds || i >= fdt->max_fdset)
break;
set = fdt->close_on_exec->fds_bits[j];
if (!set)
continue;
fdt->close_on_exec->fds_bits[j] = 0;
spin_unlock(&files->file_lock);
for ( ; set ; i++,set >>= 1) {
if (set & 1) {
sys_close(i);
}
}
spin_lock(&files->file_lock);
}
spin_unlock(&files->file_lock);
}
void get_task_comm(char *buf, struct task_struct *tsk)
{
/* buf must be at least sizeof(tsk->comm) in size */
task_lock(tsk);
strncpy(buf, tsk->comm, sizeof(tsk->comm));
task_unlock(tsk);
}
void set_task_comm(struct task_struct *tsk, char *buf)
{
task_lock(tsk);
strlcpy(tsk->comm, buf, sizeof(tsk->comm));
task_unlock(tsk);
}
int flush_old_exec(struct linux_binprm * bprm)
{
char * name;
int i, ch, retval;
struct files_struct *files;
char tcomm[sizeof(current->comm)];
/*
* 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;
/*
* Make sure we have private file handles. Ask the
* fork helper to do the work for us and the exit
* helper to do the cleanup of the old one.
*/
files = current->files; /* refcounted so safe to hold */
retval = unshare_files();
if (retval)
goto out;
/*
* Release all of the old mmap stuff
*/
retval = exec_mmap(bprm->mm);
if (retval)
goto mmap_failed;
bprm->mm = NULL; /* We're using it now */
/* This is the point of no return */
steal_locks(files);
put_files_struct(files);
current->sas_ss_sp = current->sas_ss_size = 0;
if (current->euid == current->uid && current->egid == current->gid)
current->mm->dumpable = 1;
[PATCH] setuid core dump Add a new `suid_dumpable' sysctl: This value can be used to query and set the core dump mode for setuid or otherwise protected/tainted binaries. The modes are 0 - (default) - traditional behaviour. Any process which has changed privilege levels or is execute only will not be dumped 1 - (debug) - all processes dump core when possible. The core dump is owned by the current user and no security is applied. This is intended for system debugging situations only. Ptrace is unchecked. 2 - (suidsafe) - any binary which normally would not be dumped is dumped readable by root only. This allows the end user to remove such a dump but not access it directly. For security reasons core dumps in this mode will not overwrite one another or other files. This mode is appropriate when adminstrators are attempting to debug problems in a normal environment. (akpm: > > +EXPORT_SYMBOL(suid_dumpable); > > EXPORT_SYMBOL_GPL? No problem to me. > > if (current->euid == current->uid && current->egid == current->gid) > > current->mm->dumpable = 1; > > Should this be SUID_DUMP_USER? Actually the feedback I had from last time was that the SUID_ defines should go because its clearer to follow the numbers. They can go everywhere (and there are lots of places where dumpable is tested/used as a bool in untouched code) > Maybe this should be renamed to `dump_policy' or something. Doing that > would help us catch any code which isn't using the #defines, too. Fair comment. The patch was designed to be easy to maintain for Red Hat rather than for merging. Changing that field would create a gigantic diff because it is used all over the place. ) Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:43 +00:00
else
current->mm->dumpable = suid_dumpable;
name = bprm->filename;
/* Copies the binary name from after last slash */
for (i=0; (ch = *(name++)) != '\0';) {
if (ch == '/')
i = 0; /* overwrite what we wrote */
else
if (i < (sizeof(tcomm) - 1))
tcomm[i++] = ch;
}
tcomm[i] = '\0';
set_task_comm(current, tcomm);
current->flags &= ~PF_RANDOMIZE;
flush_thread();
if (bprm->e_uid != current->euid || bprm->e_gid != current->egid ||
file_permission(bprm->file, MAY_READ) ||
(bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
suid_keys(current);
[PATCH] setuid core dump Add a new `suid_dumpable' sysctl: This value can be used to query and set the core dump mode for setuid or otherwise protected/tainted binaries. The modes are 0 - (default) - traditional behaviour. Any process which has changed privilege levels or is execute only will not be dumped 1 - (debug) - all processes dump core when possible. The core dump is owned by the current user and no security is applied. This is intended for system debugging situations only. Ptrace is unchecked. 2 - (suidsafe) - any binary which normally would not be dumped is dumped readable by root only. This allows the end user to remove such a dump but not access it directly. For security reasons core dumps in this mode will not overwrite one another or other files. This mode is appropriate when adminstrators are attempting to debug problems in a normal environment. (akpm: > > +EXPORT_SYMBOL(suid_dumpable); > > EXPORT_SYMBOL_GPL? No problem to me. > > if (current->euid == current->uid && current->egid == current->gid) > > current->mm->dumpable = 1; > > Should this be SUID_DUMP_USER? Actually the feedback I had from last time was that the SUID_ defines should go because its clearer to follow the numbers. They can go everywhere (and there are lots of places where dumpable is tested/used as a bool in untouched code) > Maybe this should be renamed to `dump_policy' or something. Doing that > would help us catch any code which isn't using the #defines, too. Fair comment. The patch was designed to be easy to maintain for Red Hat rather than for merging. Changing that field would create a gigantic diff because it is used all over the place. ) Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:43 +00:00
current->mm->dumpable = suid_dumpable;
}
/* An exec changes our domain. We are no longer part of the thread
group */
current->self_exec_id++;
flush_signal_handlers(current, 0);
flush_old_files(current->files);
return 0;
mmap_failed:
put_files_struct(current->files);
current->files = files;
out:
return retval;
}
EXPORT_SYMBOL(flush_old_exec);
/*
* Fill the binprm structure from the inode.
* Check permissions, then read the first 128 (BINPRM_BUF_SIZE) bytes
*/
int prepare_binprm(struct linux_binprm *bprm)
{
int mode;
struct inode * inode = bprm->file->f_dentry->d_inode;
int retval;
mode = inode->i_mode;
/*
* Check execute perms again - if the caller has CAP_DAC_OVERRIDE,
* generic_permission lets a non-executable through
*/
if (!(mode & 0111)) /* with at least _one_ execute bit set */
return -EACCES;
if (bprm->file->f_op == NULL)
return -EACCES;
bprm->e_uid = current->euid;
bprm->e_gid = current->egid;
if(!(bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)) {
/* Set-uid? */
if (mode & S_ISUID) {
current->personality &= ~PER_CLEAR_ON_SETID;
bprm->e_uid = inode->i_uid;
}
/* Set-gid? */
/*
* If setgid is set but no group execute bit then this
* is a candidate for mandatory locking, not a setgid
* executable.
*/
if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
current->personality &= ~PER_CLEAR_ON_SETID;
bprm->e_gid = inode->i_gid;
}
}
/* fill in binprm security blob */
retval = security_bprm_set(bprm);
if (retval)
return retval;
memset(bprm->buf,0,BINPRM_BUF_SIZE);
return kernel_read(bprm->file,0,bprm->buf,BINPRM_BUF_SIZE);
}
EXPORT_SYMBOL(prepare_binprm);
static inline int unsafe_exec(struct task_struct *p)
{
int unsafe = 0;
if (p->ptrace & PT_PTRACED) {
if (p->ptrace & PT_PTRACE_CAP)
unsafe |= LSM_UNSAFE_PTRACE_CAP;
else
unsafe |= LSM_UNSAFE_PTRACE;
}
if (atomic_read(&p->fs->count) > 1 ||
atomic_read(&p->files->count) > 1 ||
atomic_read(&p->sighand->count) > 1)
unsafe |= LSM_UNSAFE_SHARE;
return unsafe;
}
void compute_creds(struct linux_binprm *bprm)
{
int unsafe;
if (bprm->e_uid != current->uid)
suid_keys(current);
exec_keys(current);
task_lock(current);
unsafe = unsafe_exec(current);
security_bprm_apply_creds(bprm, unsafe);
task_unlock(current);
security_bprm_post_apply_creds(bprm);
}
EXPORT_SYMBOL(compute_creds);
void remove_arg_zero(struct linux_binprm *bprm)
{
if (bprm->argc) {
unsigned long offset;
char * kaddr;
struct page *page;
offset = bprm->p % PAGE_SIZE;
goto inside;
while (bprm->p++, *(kaddr+offset++)) {
if (offset != PAGE_SIZE)
continue;
offset = 0;
kunmap_atomic(kaddr, KM_USER0);
inside:
page = bprm->page[bprm->p/PAGE_SIZE];
kaddr = kmap_atomic(page, KM_USER0);
}
kunmap_atomic(kaddr, KM_USER0);
bprm->argc--;
}
}
EXPORT_SYMBOL(remove_arg_zero);
/*
* cycle the list of binary formats handler, until one recognizes the image
*/
int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
{
int try,retval;
struct linux_binfmt *fmt;
#ifdef __alpha__
/* handle /sbin/loader.. */
{
struct exec * eh = (struct exec *) bprm->buf;
if (!bprm->loader && eh->fh.f_magic == 0x183 &&
(eh->fh.f_flags & 0x3000) == 0x3000)
{
struct file * file;
unsigned long loader;
allow_write_access(bprm->file);
fput(bprm->file);
bprm->file = NULL;
loader = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
file = open_exec("/sbin/loader");
retval = PTR_ERR(file);
if (IS_ERR(file))
return retval;
/* Remember if the application is TASO. */
bprm->sh_bang = eh->ah.entry < 0x100000000UL;
bprm->file = file;
bprm->loader = loader;
retval = prepare_binprm(bprm);
if (retval<0)
return retval;
/* should call search_binary_handler recursively here,
but it does not matter */
}
}
#endif
retval = security_bprm_check(bprm);
if (retval)
return retval;
/* kernel module loader fixup */
/* so we don't try to load run modprobe in kernel space. */
set_fs(USER_DS);
retval = -ENOENT;
for (try=0; try<2; try++) {
read_lock(&binfmt_lock);
for (fmt = formats ; fmt ; fmt = fmt->next) {
int (*fn)(struct linux_binprm *, struct pt_regs *) = fmt->load_binary;
if (!fn)
continue;
if (!try_module_get(fmt->module))
continue;
read_unlock(&binfmt_lock);
retval = fn(bprm, regs);
if (retval >= 0) {
put_binfmt(fmt);
allow_write_access(bprm->file);
if (bprm->file)
fput(bprm->file);
bprm->file = NULL;
current->did_exec = 1;
proc_exec_connector(current);
return retval;
}
read_lock(&binfmt_lock);
put_binfmt(fmt);
if (retval != -ENOEXEC || bprm->mm == NULL)
break;
if (!bprm->file) {
read_unlock(&binfmt_lock);
return retval;
}
}
read_unlock(&binfmt_lock);
if (retval != -ENOEXEC || bprm->mm == NULL) {
break;
#ifdef CONFIG_KMOD
}else{
#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
if (printable(bprm->buf[0]) &&
printable(bprm->buf[1]) &&
printable(bprm->buf[2]) &&
printable(bprm->buf[3]))
break; /* -ENOEXEC */
request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
#endif
}
}
return retval;
}
EXPORT_SYMBOL(search_binary_handler);
/*
* sys_execve() executes a new program.
*/
int do_execve(char * filename,
char __user *__user *argv,
char __user *__user *envp,
struct pt_regs * regs)
{
struct linux_binprm *bprm;
struct file *file;
int retval;
int i;
retval = -ENOMEM;
bprm = kmalloc(sizeof(*bprm), GFP_KERNEL);
if (!bprm)
goto out_ret;
memset(bprm, 0, sizeof(*bprm));
file = open_exec(filename);
retval = PTR_ERR(file);
if (IS_ERR(file))
goto out_kfree;
sched_exec();
bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
bprm->file = file;
bprm->filename = filename;
bprm->interp = filename;
bprm->mm = mm_alloc();
retval = -ENOMEM;
if (!bprm->mm)
goto out_file;
retval = init_new_context(current, bprm->mm);
if (retval < 0)
goto out_mm;
bprm->argc = count(argv, bprm->p / sizeof(void *));
if ((retval = bprm->argc) < 0)
goto out_mm;
bprm->envc = count(envp, bprm->p / sizeof(void *));
if ((retval = bprm->envc) < 0)
goto out_mm;
retval = security_bprm_alloc(bprm);
if (retval)
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;
retval = search_binary_handler(bprm,regs);
if (retval >= 0) {
free_arg_pages(bprm);
/* execve success */
security_bprm_free(bprm);
acct_update_integrals(current);
kfree(bprm);
return retval;
}
out:
/* Something went wrong, return the inode and free the argument pages*/
for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
struct page * page = bprm->page[i];
if (page)
__free_page(page);
}
if (bprm->security)
security_bprm_free(bprm);
out_mm:
if (bprm->mm)
mmdrop(bprm->mm);
out_file:
if (bprm->file) {
allow_write_access(bprm->file);
fput(bprm->file);
}
out_kfree:
kfree(bprm);
out_ret:
return retval;
}
int set_binfmt(struct linux_binfmt *new)
{
struct linux_binfmt *old = current->binfmt;
if (new) {
if (!try_module_get(new->module))
return -1;
}
current->binfmt = new;
if (old)
module_put(old->module);
return 0;
}
EXPORT_SYMBOL(set_binfmt);
#define CORENAME_MAX_SIZE 64
/* format_corename will inspect the pattern parameter, and output a
* name into corename, which must have space for at least
* CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
*/
static void format_corename(char *corename, const char *pattern, long signr)
{
const char *pat_ptr = pattern;
char *out_ptr = corename;
char *const out_end = corename + CORENAME_MAX_SIZE;
int rc;
int pid_in_pattern = 0;
/* Repeat as long as we have more pattern to process and more output
space */
while (*pat_ptr) {
if (*pat_ptr != '%') {
if (out_ptr == out_end)
goto out;
*out_ptr++ = *pat_ptr++;
} else {
switch (*++pat_ptr) {
case 0:
goto out;
/* Double percent, output one percent */
case '%':
if (out_ptr == out_end)
goto out;
*out_ptr++ = '%';
break;
/* pid */
case 'p':
pid_in_pattern = 1;
rc = snprintf(out_ptr, out_end - out_ptr,
"%d", current->tgid);
if (rc > out_end - out_ptr)
goto out;
out_ptr += rc;
break;
/* uid */
case 'u':
rc = snprintf(out_ptr, out_end - out_ptr,
"%d", current->uid);
if (rc > out_end - out_ptr)
goto out;
out_ptr += rc;
break;
/* gid */
case 'g':
rc = snprintf(out_ptr, out_end - out_ptr,
"%d", current->gid);
if (rc > out_end - out_ptr)
goto out;
out_ptr += rc;
break;
/* signal that caused the coredump */
case 's':
rc = snprintf(out_ptr, out_end - out_ptr,
"%ld", signr);
if (rc > out_end - out_ptr)
goto out;
out_ptr += rc;
break;
/* UNIX time of coredump */
case 't': {
struct timeval tv;
do_gettimeofday(&tv);
rc = snprintf(out_ptr, out_end - out_ptr,
"%lu", tv.tv_sec);
if (rc > out_end - out_ptr)
goto out;
out_ptr += rc;
break;
}
/* hostname */
case 'h':
down_read(&uts_sem);
rc = snprintf(out_ptr, out_end - out_ptr,
"%s", system_utsname.nodename);
up_read(&uts_sem);
if (rc > out_end - out_ptr)
goto out;
out_ptr += rc;
break;
/* executable */
case 'e':
rc = snprintf(out_ptr, out_end - out_ptr,
"%s", current->comm);
if (rc > out_end - out_ptr)
goto out;
out_ptr += rc;
break;
default:
break;
}
++pat_ptr;
}
}
/* Backward compatibility with core_uses_pid:
*
* If core_pattern does not include a %p (as is the default)
* and core_uses_pid is set, then .%pid will be appended to
* the filename */
if (!pid_in_pattern
&& (core_uses_pid || atomic_read(&current->mm->mm_users) != 1)) {
rc = snprintf(out_ptr, out_end - out_ptr,
".%d", current->tgid);
if (rc > out_end - out_ptr)
goto out;
out_ptr += rc;
}
out:
*out_ptr = 0;
}
static void zap_threads (struct mm_struct *mm)
{
struct task_struct *g, *p;
struct task_struct *tsk = current;
struct completion *vfork_done = tsk->vfork_done;
int traced = 0;
/*
* Make sure nobody is waiting for us to release the VM,
* otherwise we can deadlock when we wait on each other
*/
if (vfork_done) {
tsk->vfork_done = NULL;
complete(vfork_done);
}
read_lock(&tasklist_lock);
do_each_thread(g,p)
if (mm == p->mm && p != tsk) {
force_sig_specific(SIGKILL, p);
mm->core_waiters++;
if (unlikely(p->ptrace) &&
unlikely(p->parent->mm == mm))
traced = 1;
}
while_each_thread(g,p);
read_unlock(&tasklist_lock);
if (unlikely(traced)) {
/*
* We are zapping a thread and the thread it ptraces.
* If the tracee went into a ptrace stop for exit tracing,
* we could deadlock since the tracer is waiting for this
* coredump to finish. Detach them so they can both die.
*/
write_lock_irq(&tasklist_lock);
do_each_thread(g,p) {
if (mm == p->mm && p != tsk &&
p->ptrace && p->parent->mm == mm) {
__ptrace_unlink(p);
}
} while_each_thread(g,p);
write_unlock_irq(&tasklist_lock);
}
}
static void coredump_wait(struct mm_struct *mm)
{
DECLARE_COMPLETION(startup_done);
int core_waiters;
mm->core_startup_done = &startup_done;
zap_threads(mm);
core_waiters = mm->core_waiters;
up_write(&mm->mmap_sem);
if (core_waiters)
wait_for_completion(&startup_done);
BUG_ON(mm->core_waiters);
}
int do_coredump(long signr, int exit_code, struct pt_regs * regs)
{
char corename[CORENAME_MAX_SIZE + 1];
struct mm_struct *mm = current->mm;
struct linux_binfmt * binfmt;
struct inode * inode;
struct file * file;
int retval = 0;
[PATCH] setuid core dump Add a new `suid_dumpable' sysctl: This value can be used to query and set the core dump mode for setuid or otherwise protected/tainted binaries. The modes are 0 - (default) - traditional behaviour. Any process which has changed privilege levels or is execute only will not be dumped 1 - (debug) - all processes dump core when possible. The core dump is owned by the current user and no security is applied. This is intended for system debugging situations only. Ptrace is unchecked. 2 - (suidsafe) - any binary which normally would not be dumped is dumped readable by root only. This allows the end user to remove such a dump but not access it directly. For security reasons core dumps in this mode will not overwrite one another or other files. This mode is appropriate when adminstrators are attempting to debug problems in a normal environment. (akpm: > > +EXPORT_SYMBOL(suid_dumpable); > > EXPORT_SYMBOL_GPL? No problem to me. > > if (current->euid == current->uid && current->egid == current->gid) > > current->mm->dumpable = 1; > > Should this be SUID_DUMP_USER? Actually the feedback I had from last time was that the SUID_ defines should go because its clearer to follow the numbers. They can go everywhere (and there are lots of places where dumpable is tested/used as a bool in untouched code) > Maybe this should be renamed to `dump_policy' or something. Doing that > would help us catch any code which isn't using the #defines, too. Fair comment. The patch was designed to be easy to maintain for Red Hat rather than for merging. Changing that field would create a gigantic diff because it is used all over the place. ) Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:43 +00:00
int fsuid = current->fsuid;
int flag = 0;
binfmt = current->binfmt;
if (!binfmt || !binfmt->core_dump)
goto fail;
down_write(&mm->mmap_sem);
if (!mm->dumpable) {
up_write(&mm->mmap_sem);
goto fail;
}
[PATCH] setuid core dump Add a new `suid_dumpable' sysctl: This value can be used to query and set the core dump mode for setuid or otherwise protected/tainted binaries. The modes are 0 - (default) - traditional behaviour. Any process which has changed privilege levels or is execute only will not be dumped 1 - (debug) - all processes dump core when possible. The core dump is owned by the current user and no security is applied. This is intended for system debugging situations only. Ptrace is unchecked. 2 - (suidsafe) - any binary which normally would not be dumped is dumped readable by root only. This allows the end user to remove such a dump but not access it directly. For security reasons core dumps in this mode will not overwrite one another or other files. This mode is appropriate when adminstrators are attempting to debug problems in a normal environment. (akpm: > > +EXPORT_SYMBOL(suid_dumpable); > > EXPORT_SYMBOL_GPL? No problem to me. > > if (current->euid == current->uid && current->egid == current->gid) > > current->mm->dumpable = 1; > > Should this be SUID_DUMP_USER? Actually the feedback I had from last time was that the SUID_ defines should go because its clearer to follow the numbers. They can go everywhere (and there are lots of places where dumpable is tested/used as a bool in untouched code) > Maybe this should be renamed to `dump_policy' or something. Doing that > would help us catch any code which isn't using the #defines, too. Fair comment. The patch was designed to be easy to maintain for Red Hat rather than for merging. Changing that field would create a gigantic diff because it is used all over the place. ) Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:43 +00:00
/*
* We cannot trust fsuid as being the "true" uid of the
* process nor do we know its entire history. We only know it
* was tainted so we dump it as root in mode 2.
*/
if (mm->dumpable == 2) { /* Setuid core dump mode */
flag = O_EXCL; /* Stop rewrite attacks */
current->fsuid = 0; /* Dump root private */
}
mm->dumpable = 0;
retval = -EAGAIN;
spin_lock_irq(&current->sighand->siglock);
if (!(current->signal->flags & SIGNAL_GROUP_EXIT)) {
current->signal->flags = SIGNAL_GROUP_EXIT;
current->signal->group_exit_code = exit_code;
current->signal->group_stop_count = 0;
retval = 0;
}
spin_unlock_irq(&current->sighand->siglock);
if (retval) {
up_write(&mm->mmap_sem);
goto fail;
}
init_completion(&mm->core_done);
coredump_wait(mm);
/*
* Clear any false indication of pending signals that might
* be seen by the filesystem code called to write the core file.
*/
clear_thread_flag(TIF_SIGPENDING);
if (current->signal->rlim[RLIMIT_CORE].rlim_cur < binfmt->min_coredump)
goto fail_unlock;
/*
* lock_kernel() because format_corename() is controlled by sysctl, which
* uses lock_kernel()
*/
lock_kernel();
format_corename(corename, core_pattern, signr);
unlock_kernel();
[PATCH] setuid core dump Add a new `suid_dumpable' sysctl: This value can be used to query and set the core dump mode for setuid or otherwise protected/tainted binaries. The modes are 0 - (default) - traditional behaviour. Any process which has changed privilege levels or is execute only will not be dumped 1 - (debug) - all processes dump core when possible. The core dump is owned by the current user and no security is applied. This is intended for system debugging situations only. Ptrace is unchecked. 2 - (suidsafe) - any binary which normally would not be dumped is dumped readable by root only. This allows the end user to remove such a dump but not access it directly. For security reasons core dumps in this mode will not overwrite one another or other files. This mode is appropriate when adminstrators are attempting to debug problems in a normal environment. (akpm: > > +EXPORT_SYMBOL(suid_dumpable); > > EXPORT_SYMBOL_GPL? No problem to me. > > if (current->euid == current->uid && current->egid == current->gid) > > current->mm->dumpable = 1; > > Should this be SUID_DUMP_USER? Actually the feedback I had from last time was that the SUID_ defines should go because its clearer to follow the numbers. They can go everywhere (and there are lots of places where dumpable is tested/used as a bool in untouched code) > Maybe this should be renamed to `dump_policy' or something. Doing that > would help us catch any code which isn't using the #defines, too. Fair comment. The patch was designed to be easy to maintain for Red Hat rather than for merging. Changing that field would create a gigantic diff because it is used all over the place. ) Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:43 +00:00
file = filp_open(corename, O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag, 0600);
if (IS_ERR(file))
goto fail_unlock;
inode = file->f_dentry->d_inode;
if (inode->i_nlink > 1)
goto close_fail; /* multiple links - don't dump */
if (d_unhashed(file->f_dentry))
goto close_fail;
if (!S_ISREG(inode->i_mode))
goto close_fail;
if (!file->f_op)
goto close_fail;
if (!file->f_op->write)
goto close_fail;
if (do_truncate(file->f_dentry, 0, 0, file) != 0)
goto close_fail;
retval = binfmt->core_dump(signr, regs, file);
if (retval)
current->signal->group_exit_code |= 0x80;
close_fail:
filp_close(file, NULL);
fail_unlock:
[PATCH] setuid core dump Add a new `suid_dumpable' sysctl: This value can be used to query and set the core dump mode for setuid or otherwise protected/tainted binaries. The modes are 0 - (default) - traditional behaviour. Any process which has changed privilege levels or is execute only will not be dumped 1 - (debug) - all processes dump core when possible. The core dump is owned by the current user and no security is applied. This is intended for system debugging situations only. Ptrace is unchecked. 2 - (suidsafe) - any binary which normally would not be dumped is dumped readable by root only. This allows the end user to remove such a dump but not access it directly. For security reasons core dumps in this mode will not overwrite one another or other files. This mode is appropriate when adminstrators are attempting to debug problems in a normal environment. (akpm: > > +EXPORT_SYMBOL(suid_dumpable); > > EXPORT_SYMBOL_GPL? No problem to me. > > if (current->euid == current->uid && current->egid == current->gid) > > current->mm->dumpable = 1; > > Should this be SUID_DUMP_USER? Actually the feedback I had from last time was that the SUID_ defines should go because its clearer to follow the numbers. They can go everywhere (and there are lots of places where dumpable is tested/used as a bool in untouched code) > Maybe this should be renamed to `dump_policy' or something. Doing that > would help us catch any code which isn't using the #defines, too. Fair comment. The patch was designed to be easy to maintain for Red Hat rather than for merging. Changing that field would create a gigantic diff because it is used all over the place. ) Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:43 +00:00
current->fsuid = fsuid;
complete_all(&mm->core_done);
fail:
return retval;
}