exec_domain.c
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/*
* Handling of different ABIs (personalities).
*
* We group personalities into execution domains which have their
* own handlers for kernel entry points, signal mapping, etc...
*
* 2001-05-06 Complete rewrite, Christoph Hellwig (hch@infradead.org)
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/kmod.h>
#include <linux/module.h>
#include <linux/personality.h>
#include <linux/proc_fs.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/syscalls.h>
#include <linux/sysctl.h>
#include <linux/types.h>
#include <linux/fs_struct.h>
static void default_handler(int, struct pt_regs *);
static struct exec_domain *exec_domains = &default_exec_domain;
static DEFINE_RWLOCK(exec_domains_lock);
static u_long ident_map[32] = {
0, 1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12, 13, 14, 15,
16, 17, 18, 19, 20, 21, 22, 23,
24, 25, 26, 27, 28, 29, 30, 31
};
struct exec_domain default_exec_domain = {
.name = "Linux", /* name */
.handler = default_handler, /* lcall7 causes a seg fault. */
.pers_low = 0, /* PER_LINUX personality. */
.pers_high = 0, /* PER_LINUX personality. */
.signal_map = ident_map, /* Identity map signals. */
.signal_invmap = ident_map, /* - both ways. */
};
static void
default_handler(int segment, struct pt_regs *regp)
{
set_personality(0);
if (current_thread_info()->exec_domain->handler != default_handler)
current_thread_info()->exec_domain->handler(segment, regp);
else
send_sig(SIGSEGV, current, 1);
}
static struct exec_domain *
lookup_exec_domain(u_long personality)
{
struct exec_domain * ep;
u_long pers = personality(personality);
read_lock(&exec_domains_lock);
for (ep = exec_domains; ep; ep = ep->next) {
if (pers >= ep->pers_low && pers <= ep->pers_high)
if (try_module_get(ep->module))
goto out;
}
#ifdef CONFIG_MODULES
read_unlock(&exec_domains_lock);
request_module("personality-%ld", pers);
read_lock(&exec_domains_lock);
for (ep = exec_domains; ep; ep = ep->next) {
if (pers >= ep->pers_low && pers <= ep->pers_high)
if (try_module_get(ep->module))
goto out;
}
#endif
ep = &default_exec_domain;
out:
read_unlock(&exec_domains_lock);
return (ep);
}
int
register_exec_domain(struct exec_domain *ep)
{
struct exec_domain *tmp;
int err = -EBUSY;
if (ep == NULL)
return -EINVAL;
if (ep->next != NULL)
return -EBUSY;
write_lock(&exec_domains_lock);
for (tmp = exec_domains; tmp; tmp = tmp->next) {
if (tmp == ep)
goto out;
}
ep->next = exec_domains;
exec_domains = ep;
err = 0;
out:
write_unlock(&exec_domains_lock);
return (err);
}
int
unregister_exec_domain(struct exec_domain *ep)
{
struct exec_domain **epp;
epp = &exec_domains;
write_lock(&exec_domains_lock);
for (epp = &exec_domains; *epp; epp = &(*epp)->next) {
if (ep == *epp)
goto unregister;
}
write_unlock(&exec_domains_lock);
return -EINVAL;
unregister:
*epp = ep->next;
ep->next = NULL;
write_unlock(&exec_domains_lock);
return 0;
}
int
__set_personality(u_long personality)
{
struct exec_domain *ep, *oep;
ep = lookup_exec_domain(personality);
if (ep == current_thread_info()->exec_domain) {
current->personality = personality;
module_put(ep->module);
return 0;
}
current->personality = personality;
oep = current_thread_info()->exec_domain;
current_thread_info()->exec_domain = ep;
module_put(oep->module);
return 0;
}
#ifdef CONFIG_PROC_FS
static int execdomains_proc_show(struct seq_file *m, void *v)
{
struct exec_domain *ep;
read_lock(&exec_domains_lock);
for (ep = exec_domains; ep; ep = ep->next)
seq_printf(m, "%d-%d\t%-16s\t[%s]\n",
ep->pers_low, ep->pers_high, ep->name,
module_name(ep->module));
read_unlock(&exec_domains_lock);
return 0;
}
static int execdomains_proc_open(struct inode *inode, struct file *file)
{
return single_open(file, execdomains_proc_show, NULL);
}
static const struct file_operations execdomains_proc_fops = {
.open = execdomains_proc_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
static int __init proc_execdomains_init(void)
{
proc_create("execdomains", 0, NULL, &execdomains_proc_fops);
return 0;
}
module_init(proc_execdomains_init);
#endif
SYSCALL_DEFINE1(personality, u_long, personality)
{
u_long old = current->personality;
if (personality != 0xffffffff) {
set_personality(personality);
if (current->personality != personality)
return -EINVAL;
}
return (long)old;
}
EXPORT_SYMBOL(register_exec_domain);
EXPORT_SYMBOL(unregister_exec_domain);
EXPORT_SYMBOL(__set_personality);