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![Oleg Nesterov](/assets/img/avatar_default.png)
Cleanup, no functional changes. - __set_personality() always changes ->exec_domain/personality, the special case when ->exec_domain remains the same buys nothing but complicates the code. Unify both cases to simplify the code. - The -EINVAL check in sys_personality() was never right. If we assume that set_personality() can fail we should check the value it returns instead of verifying that task->personality was actually changed. Remove it. Before the previous patch it was possible to hit this case due to overflow problems, but this -EINVAL just indicated the kernel bug. OTOH, probably it makes sense to change lookup_exec_domain() to return ERR_PTR() instead of default_exec_domain if the search in exec_domains list fails, and report this error to the user-space. But this means another user-space change, and we have in-kernel users which need fixes. For example, PER_OSF4 falls into PER_MASK for unkown reason and nobody cares to register this domain. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Wenming Zhang <wezhang@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
195 lines
4.3 KiB
C
195 lines
4.3 KiB
C
/*
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* Handling of different ABIs (personalities).
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*
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* We group personalities into execution domains which have their
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* own handlers for kernel entry points, signal mapping, etc...
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*
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* 2001-05-06 Complete rewrite, Christoph Hellwig (hch@infradead.org)
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*/
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/kmod.h>
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#include <linux/module.h>
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#include <linux/personality.h>
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#include <linux/proc_fs.h>
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#include <linux/sched.h>
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#include <linux/seq_file.h>
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#include <linux/syscalls.h>
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#include <linux/sysctl.h>
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#include <linux/types.h>
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#include <linux/fs_struct.h>
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static void default_handler(int, struct pt_regs *);
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static struct exec_domain *exec_domains = &default_exec_domain;
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static DEFINE_RWLOCK(exec_domains_lock);
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static unsigned long ident_map[32] = {
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0, 1, 2, 3, 4, 5, 6, 7,
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8, 9, 10, 11, 12, 13, 14, 15,
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16, 17, 18, 19, 20, 21, 22, 23,
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24, 25, 26, 27, 28, 29, 30, 31
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};
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struct exec_domain default_exec_domain = {
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.name = "Linux", /* name */
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.handler = default_handler, /* lcall7 causes a seg fault. */
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.pers_low = 0, /* PER_LINUX personality. */
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.pers_high = 0, /* PER_LINUX personality. */
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.signal_map = ident_map, /* Identity map signals. */
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.signal_invmap = ident_map, /* - both ways. */
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};
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static void
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default_handler(int segment, struct pt_regs *regp)
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{
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set_personality(0);
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if (current_thread_info()->exec_domain->handler != default_handler)
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current_thread_info()->exec_domain->handler(segment, regp);
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else
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send_sig(SIGSEGV, current, 1);
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}
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static struct exec_domain *
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lookup_exec_domain(unsigned int personality)
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{
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unsigned int pers = personality(personality);
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struct exec_domain *ep;
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read_lock(&exec_domains_lock);
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for (ep = exec_domains; ep; ep = ep->next) {
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if (pers >= ep->pers_low && pers <= ep->pers_high)
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if (try_module_get(ep->module))
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goto out;
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}
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#ifdef CONFIG_MODULES
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read_unlock(&exec_domains_lock);
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request_module("personality-%d", pers);
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read_lock(&exec_domains_lock);
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for (ep = exec_domains; ep; ep = ep->next) {
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if (pers >= ep->pers_low && pers <= ep->pers_high)
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if (try_module_get(ep->module))
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goto out;
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}
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#endif
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ep = &default_exec_domain;
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out:
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read_unlock(&exec_domains_lock);
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return (ep);
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}
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int
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register_exec_domain(struct exec_domain *ep)
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{
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struct exec_domain *tmp;
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int err = -EBUSY;
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if (ep == NULL)
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return -EINVAL;
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if (ep->next != NULL)
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return -EBUSY;
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write_lock(&exec_domains_lock);
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for (tmp = exec_domains; tmp; tmp = tmp->next) {
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if (tmp == ep)
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goto out;
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}
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ep->next = exec_domains;
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exec_domains = ep;
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err = 0;
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out:
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write_unlock(&exec_domains_lock);
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return (err);
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}
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int
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unregister_exec_domain(struct exec_domain *ep)
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{
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struct exec_domain **epp;
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epp = &exec_domains;
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write_lock(&exec_domains_lock);
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for (epp = &exec_domains; *epp; epp = &(*epp)->next) {
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if (ep == *epp)
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goto unregister;
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}
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write_unlock(&exec_domains_lock);
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return -EINVAL;
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unregister:
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*epp = ep->next;
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ep->next = NULL;
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write_unlock(&exec_domains_lock);
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return 0;
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}
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int __set_personality(unsigned int personality)
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{
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struct exec_domain *oep = current_thread_info()->exec_domain;
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current_thread_info()->exec_domain = lookup_exec_domain(personality);
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current->personality = personality;
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module_put(oep->module);
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return 0;
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}
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#ifdef CONFIG_PROC_FS
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static int execdomains_proc_show(struct seq_file *m, void *v)
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{
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struct exec_domain *ep;
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read_lock(&exec_domains_lock);
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for (ep = exec_domains; ep; ep = ep->next)
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seq_printf(m, "%d-%d\t%-16s\t[%s]\n",
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ep->pers_low, ep->pers_high, ep->name,
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module_name(ep->module));
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read_unlock(&exec_domains_lock);
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return 0;
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}
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static int execdomains_proc_open(struct inode *inode, struct file *file)
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{
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return single_open(file, execdomains_proc_show, NULL);
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}
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static const struct file_operations execdomains_proc_fops = {
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.open = execdomains_proc_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = single_release,
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};
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static int __init proc_execdomains_init(void)
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{
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proc_create("execdomains", 0, NULL, &execdomains_proc_fops);
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return 0;
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}
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module_init(proc_execdomains_init);
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#endif
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SYSCALL_DEFINE1(personality, unsigned int, personality)
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{
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unsigned int old = current->personality;
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if (personality != 0xffffffff)
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set_personality(personality);
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return old;
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}
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EXPORT_SYMBOL(register_exec_domain);
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EXPORT_SYMBOL(unregister_exec_domain);
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EXPORT_SYMBOL(__set_personality);
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