diff options
Diffstat (limited to 'arch/um/sys-i386/ldt.c')
-rw-r--r-- | arch/um/sys-i386/ldt.c | 509 |
1 files changed, 474 insertions, 35 deletions
diff --git a/arch/um/sys-i386/ldt.c b/arch/um/sys-i386/ldt.c index 36b5c2c1328..17746b4c08f 100644 --- a/arch/um/sys-i386/ldt.c +++ b/arch/um/sys-i386/ldt.c @@ -3,53 +3,26 @@ * Licensed under the GPL */ +#include "linux/stddef.h" #include "linux/config.h" #include "linux/sched.h" #include "linux/slab.h" #include "linux/types.h" +#include "linux/errno.h" #include "asm/uaccess.h" -#include "asm/ptrace.h" #include "asm/smp.h" #include "asm/ldt.h" +#include "asm/unistd.h" #include "choose-mode.h" #include "kern.h" #include "mode_kern.h" -#ifdef CONFIG_MODE_TT - extern int modify_ldt(int func, void *ptr, unsigned long bytecount); -static int do_modify_ldt_tt(int func, void *ptr, unsigned long bytecount) -{ - return modify_ldt(func, ptr, bytecount); -} - -#endif - -#ifdef CONFIG_MODE_SKAS - -#include "skas.h" -#include "skas_ptrace.h" - -static int do_modify_ldt_skas(int func, void *ptr, unsigned long bytecount) -{ - struct ptrace_ldt ldt; - u32 cpu; - int res; - - ldt = ((struct ptrace_ldt) { .func = func, - .ptr = ptr, - .bytecount = bytecount }); - - cpu = get_cpu(); - res = ptrace(PTRACE_LDT, userspace_pid[cpu], 0, (unsigned long) &ldt); - put_cpu(); - - return res; -} -#endif +#ifdef CONFIG_MODE_TT -int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount) +static long do_modify_ldt_tt(int func, void __user *ptr, + unsigned long bytecount) { struct user_desc info; int res = 0; @@ -89,8 +62,7 @@ int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount) goto out; } - res = CHOOSE_MODE_PROC(do_modify_ldt_tt, do_modify_ldt_skas, func, - p, bytecount); + res = modify_ldt(func, p, bytecount); if(res < 0) goto out; @@ -108,3 +80,470 @@ out: kfree(buf); return res; } + +#endif + +#ifdef CONFIG_MODE_SKAS + +#include "skas.h" +#include "skas_ptrace.h" +#include "asm/mmu_context.h" + +long write_ldt_entry(struct mm_id * mm_idp, int func, struct user_desc * desc, + void **addr, int done) +{ + long res; + + if(proc_mm){ + /* This is a special handling for the case, that the mm to + * modify isn't current->active_mm. + * If this is called directly by modify_ldt, + * (current->active_mm->context.skas.u == mm_idp) + * will be true. So no call to switch_mm_skas(mm_idp) is done. + * If this is called in case of init_new_ldt or PTRACE_LDT, + * mm_idp won't belong to current->active_mm, but child->mm. + * So we need to switch child's mm into our userspace, then + * later switch back. + * + * Note: I'm unshure: should interrupts be disabled here? + */ + if(!current->active_mm || current->active_mm == &init_mm || + mm_idp != ¤t->active_mm->context.skas.id) + switch_mm_skas(mm_idp); + } + + if(ptrace_ldt) { + struct ptrace_ldt ldt_op = (struct ptrace_ldt) { + .func = func, + .ptr = desc, + .bytecount = sizeof(*desc)}; + u32 cpu; + int pid; + + if(!proc_mm) + pid = mm_idp->u.pid; + else { + cpu = get_cpu(); + pid = userspace_pid[cpu]; + } + + res = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op); + if(res) + res = errno; + + if(proc_mm) + put_cpu(); + } + else { + void *stub_addr; + res = syscall_stub_data(mm_idp, (unsigned long *)desc, + (sizeof(*desc) + sizeof(long) - 1) & + ~(sizeof(long) - 1), + addr, &stub_addr); + if(!res){ + unsigned long args[] = { func, + (unsigned long)stub_addr, + sizeof(*desc), + 0, 0, 0 }; + res = run_syscall_stub(mm_idp, __NR_modify_ldt, args, + 0, addr, done); + } + } + + if(proc_mm){ + /* This is the second part of special handling, that makes + * PTRACE_LDT possible to implement. + */ + if(current->active_mm && current->active_mm != &init_mm && + mm_idp != ¤t->active_mm->context.skas.id) + switch_mm_skas(¤t->active_mm->context.skas.id); + } + + return res; +} + +static long read_ldt_from_host(void __user * ptr, unsigned long bytecount) +{ + int res, n; + struct ptrace_ldt ptrace_ldt = (struct ptrace_ldt) { + .func = 0, + .bytecount = bytecount, + .ptr = (void *)kmalloc(bytecount, GFP_KERNEL)}; + u32 cpu; + + if(ptrace_ldt.ptr == NULL) + return -ENOMEM; + + /* This is called from sys_modify_ldt only, so userspace_pid gives + * us the right number + */ + + cpu = get_cpu(); + res = ptrace(PTRACE_LDT, userspace_pid[cpu], 0, + (unsigned long) &ptrace_ldt); + put_cpu(); + if(res < 0) + goto out; + + n = copy_to_user(ptr, ptrace_ldt.ptr, res); + if(n != 0) + res = -EFAULT; + + out: + kfree(ptrace_ldt.ptr); + + return res; +} + +/* + * In skas mode, we hold our own ldt data in UML. + * Thus, the code implementing sys_modify_ldt_skas + * is very similar to (and mostly stolen from) sys_modify_ldt + * for arch/i386/kernel/ldt.c + * The routines copied and modified in part are: + * - read_ldt + * - read_default_ldt + * - write_ldt + * - sys_modify_ldt_skas + */ + +static int read_ldt(void __user * ptr, unsigned long bytecount) +{ + int i, err = 0; + unsigned long size; + uml_ldt_t * ldt = ¤t->mm->context.skas.ldt; + + if(!ldt->entry_count) + goto out; + if(bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES) + bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES; + err = bytecount; + + if(ptrace_ldt){ + return read_ldt_from_host(ptr, bytecount); + } + + down(&ldt->semaphore); + if(ldt->entry_count <= LDT_DIRECT_ENTRIES){ + size = LDT_ENTRY_SIZE*LDT_DIRECT_ENTRIES; + if(size > bytecount) + size = bytecount; + if(copy_to_user(ptr, ldt->u.entries, size)) + err = -EFAULT; + bytecount -= size; + ptr += size; + } + else { + for(i=0; i<ldt->entry_count/LDT_ENTRIES_PER_PAGE && bytecount; + i++){ + size = PAGE_SIZE; + if(size > bytecount) + size = bytecount; + if(copy_to_user(ptr, ldt->u.pages[i], size)){ + err = -EFAULT; + break; + } + bytecount -= size; + ptr += size; + } + } + up(&ldt->semaphore); + + if(bytecount == 0 || err == -EFAULT) + goto out; + + if(clear_user(ptr, bytecount)) + err = -EFAULT; + +out: + return err; +} + +static int read_default_ldt(void __user * ptr, unsigned long bytecount) +{ + int err; + + if(bytecount > 5*LDT_ENTRY_SIZE) + bytecount = 5*LDT_ENTRY_SIZE; + + err = bytecount; + /* UML doesn't support lcall7 and lcall27. + * So, we don't really have a default ldt, but emulate + * an empty ldt of common host default ldt size. + */ + if(clear_user(ptr, bytecount)) + err = -EFAULT; + + return err; +} + +static int write_ldt(void __user * ptr, unsigned long bytecount, int func) +{ + uml_ldt_t * ldt = ¤t->mm->context.skas.ldt; + struct mm_id * mm_idp = ¤t->mm->context.skas.id; + int i, err; + struct user_desc ldt_info; + struct ldt_entry entry0, *ldt_p; + void *addr = NULL; + + err = -EINVAL; + if(bytecount != sizeof(ldt_info)) + goto out; + err = -EFAULT; + if(copy_from_user(&ldt_info, ptr, sizeof(ldt_info))) + goto out; + + err = -EINVAL; + if(ldt_info.entry_number >= LDT_ENTRIES) + goto out; + if(ldt_info.contents == 3){ + if (func == 1) + goto out; + if (ldt_info.seg_not_present == 0) + goto out; + } + + if(!ptrace_ldt) + down(&ldt->semaphore); + + err = write_ldt_entry(mm_idp, func, &ldt_info, &addr, 1); + if(err) + goto out_unlock; + else if(ptrace_ldt) { + /* With PTRACE_LDT available, this is used as a flag only */ + ldt->entry_count = 1; + goto out; + } + + if(ldt_info.entry_number >= ldt->entry_count && + ldt_info.entry_number >= LDT_DIRECT_ENTRIES){ + for(i=ldt->entry_count/LDT_ENTRIES_PER_PAGE; + i*LDT_ENTRIES_PER_PAGE <= ldt_info.entry_number; + i++){ + if(i == 0) + memcpy(&entry0, ldt->u.entries, + sizeof(entry0)); + ldt->u.pages[i] = (struct ldt_entry *) + __get_free_page(GFP_KERNEL|__GFP_ZERO); + if(!ldt->u.pages[i]){ + err = -ENOMEM; + /* Undo the change in host */ + memset(&ldt_info, 0, sizeof(ldt_info)); + write_ldt_entry(mm_idp, 1, &ldt_info, &addr, 1); + goto out_unlock; + } + if(i == 0) { + memcpy(ldt->u.pages[0], &entry0, + sizeof(entry0)); + memcpy(ldt->u.pages[0]+1, ldt->u.entries+1, + sizeof(entry0)*(LDT_DIRECT_ENTRIES-1)); + } + ldt->entry_count = (i + 1) * LDT_ENTRIES_PER_PAGE; + } + } + if(ldt->entry_count <= ldt_info.entry_number) + ldt->entry_count = ldt_info.entry_number + 1; + + if(ldt->entry_count <= LDT_DIRECT_ENTRIES) + ldt_p = ldt->u.entries + ldt_info.entry_number; + else + ldt_p = ldt->u.pages[ldt_info.entry_number/LDT_ENTRIES_PER_PAGE] + + ldt_info.entry_number%LDT_ENTRIES_PER_PAGE; + + if(ldt_info.base_addr == 0 && ldt_info.limit == 0 && + (func == 1 || LDT_empty(&ldt_info))){ + ldt_p->a = 0; + ldt_p->b = 0; + } + else{ + if (func == 1) + ldt_info.useable = 0; + ldt_p->a = LDT_entry_a(&ldt_info); + ldt_p->b = LDT_entry_b(&ldt_info); + } + err = 0; + +out_unlock: + up(&ldt->semaphore); +out: + return err; +} + +static long do_modify_ldt_skas(int func, void __user *ptr, + unsigned long bytecount) +{ + int ret = -ENOSYS; + + switch (func) { + case 0: + ret = read_ldt(ptr, bytecount); + break; + case 1: + case 0x11: + ret = write_ldt(ptr, bytecount, func); + break; + case 2: + ret = read_default_ldt(ptr, bytecount); + break; + } + return ret; +} + +short dummy_list[9] = {0, -1}; +short * host_ldt_entries = NULL; + +void ldt_get_host_info(void) +{ + long ret; + struct ldt_entry * ldt; + int i, size, k, order; + + host_ldt_entries = dummy_list+1; + + for(i = LDT_PAGES_MAX-1, order=0; i; i>>=1, order++); + + ldt = (struct ldt_entry *) + __get_free_pages(GFP_KERNEL|__GFP_ZERO, order); + if(ldt == NULL) { + printk("ldt_get_host_info: couldn't allocate buffer for host ldt\n"); + return; + } + + ret = modify_ldt(0, ldt, (1<<order)*PAGE_SIZE); + if(ret < 0) { + printk("ldt_get_host_info: couldn't read host ldt\n"); + goto out_free; + } + if(ret == 0) { + /* default_ldt is active, simply write an empty entry 0 */ + host_ldt_entries = dummy_list; + goto out_free; + } + + for(i=0, size=0; i<ret/LDT_ENTRY_SIZE; i++){ + if(ldt[i].a != 0 || ldt[i].b != 0) + size++; + } + + if(size < sizeof(dummy_list)/sizeof(dummy_list[0])) { + host_ldt_entries = dummy_list; + } + else { + size = (size + 1) * sizeof(dummy_list[0]); + host_ldt_entries = (short *)kmalloc(size, GFP_KERNEL); + if(host_ldt_entries == NULL) { + printk("ldt_get_host_info: couldn't allocate host ldt list\n"); + goto out_free; + } + } + + for(i=0, k=0; i<ret/LDT_ENTRY_SIZE; i++){ + if(ldt[i].a != 0 || ldt[i].b != 0) { + host_ldt_entries[k++] = i; + } + } + host_ldt_entries[k] = -1; + +out_free: + free_pages((unsigned long)ldt, order); +} + +long init_new_ldt(struct mmu_context_skas * new_mm, + struct mmu_context_skas * from_mm) +{ + struct user_desc desc; + short * num_p; + int i; + long page, err=0; + void *addr = NULL; + + memset(&desc, 0, sizeof(desc)); + + if(!ptrace_ldt) + init_MUTEX(&new_mm->ldt.semaphore); + + if(!from_mm){ + /* + * We have to initialize a clean ldt. + */ + if(proc_mm) { + /* + * If the new mm was created using proc_mm, host's + * default-ldt currently is assigned, which normally + * contains the call-gates for lcall7 and lcall27. + * To remove these gates, we simply write an empty + * entry as number 0 to the host. + */ + err = write_ldt_entry(&new_mm->id, 1, &desc, + &addr, 1); + } + else{ + /* + * Now we try to retrieve info about the ldt, we + * inherited from the host. All ldt-entries found + * will be reset in the following loop + */ + if(host_ldt_entries == NULL) + ldt_get_host_info(); + for(num_p=host_ldt_entries; *num_p != -1; num_p++){ + desc.entry_number = *num_p; + err = write_ldt_entry(&new_mm->id, 1, &desc, + &addr, *(num_p + 1) == -1); + if(err) + break; + } + } + new_mm->ldt.entry_count = 0; + } + else if (!ptrace_ldt) { + /* Our local LDT is used to supply the data for + * modify_ldt(READLDT), if PTRACE_LDT isn't available, + * i.e., we have to use the stub for modify_ldt, which + * can't handle the big read buffer of up to 64kB. + */ + down(&from_mm->ldt.semaphore); + if(from_mm->ldt.entry_count <= LDT_DIRECT_ENTRIES){ + memcpy(new_mm->ldt.u.entries, from_mm->ldt.u.entries, + sizeof(new_mm->ldt.u.entries)); + } + else{ + i = from_mm->ldt.entry_count / LDT_ENTRIES_PER_PAGE; + while(i-->0){ + page = __get_free_page(GFP_KERNEL|__GFP_ZERO); + if (!page){ + err = -ENOMEM; + break; + } + new_mm->ldt.u.pages[i] = + (struct ldt_entry *) page; + memcpy(new_mm->ldt.u.pages[i], + from_mm->ldt.u.pages[i], PAGE_SIZE); + } + } + new_mm->ldt.entry_count = from_mm->ldt.entry_count; + up(&from_mm->ldt.semaphore); + } + + return err; +} + + +void free_ldt(struct mmu_context_skas * mm) +{ + int i; + + if(!ptrace_ldt && mm->ldt.entry_count > LDT_DIRECT_ENTRIES){ + i = mm->ldt.entry_count / LDT_ENTRIES_PER_PAGE; + while(i-- > 0){ + free_page((long )mm->ldt.u.pages[i]); + } + } + mm->ldt.entry_count = 0; +} +#endif + +int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount) +{ + return(CHOOSE_MODE_PROC(do_modify_ldt_tt, do_modify_ldt_skas, func, + ptr, bytecount)); +} |