mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-24 05:04:00 +08:00
pagemap: check permissions and capabilities at open time
This patchset makes pagemap useable again in the safe way (after row hammer bug it was made CAP_SYS_ADMIN-only). This patchset restores access for non-privileged users but hides PFNs from them. Also it adds bit 'map-exclusive' which is set if page is mapped only here: it helps in estimation of working set without exposing pfns and allows to distinguish CoWed and non-CoWed private anonymous pages. Second patch removes page-shift bits and completes migration to the new pagemap format: flags soft-dirty and mmap-exclusive are available only in the new format. This patch (of 5): This patch moves permission checks from pagemap_read() into pagemap_open(). Pointer to mm is saved in file->private_data. This reference pins only mm_struct itself. /proc/*/mem, maps, smaps already work in the same way. See http://lkml.kernel.org/r/CA+55aFyKpWrt_Ajzh1rzp_GcwZ4=6Y=kOv8hBz172CFJp6L8Tg@mail.gmail.com Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reviewed-by: Mark Williamson <mwilliamson@undo-software.com> Tested-by: Mark Williamson <mwilliamson@undo-software.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
parent
b5e3aa0a4d
commit
a06db751c3
@ -1229,40 +1229,33 @@ static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
|
||||
static ssize_t pagemap_read(struct file *file, char __user *buf,
|
||||
size_t count, loff_t *ppos)
|
||||
{
|
||||
struct task_struct *task = get_proc_task(file_inode(file));
|
||||
struct mm_struct *mm;
|
||||
struct mm_struct *mm = file->private_data;
|
||||
struct pagemapread pm;
|
||||
int ret = -ESRCH;
|
||||
struct mm_walk pagemap_walk = {};
|
||||
unsigned long src;
|
||||
unsigned long svpfn;
|
||||
unsigned long start_vaddr;
|
||||
unsigned long end_vaddr;
|
||||
int copied = 0;
|
||||
int ret = 0, copied = 0;
|
||||
|
||||
if (!task)
|
||||
if (!mm || !atomic_inc_not_zero(&mm->mm_users))
|
||||
goto out;
|
||||
|
||||
ret = -EINVAL;
|
||||
/* file position must be aligned */
|
||||
if ((*ppos % PM_ENTRY_BYTES) || (count % PM_ENTRY_BYTES))
|
||||
goto out_task;
|
||||
goto out_mm;
|
||||
|
||||
ret = 0;
|
||||
if (!count)
|
||||
goto out_task;
|
||||
goto out_mm;
|
||||
|
||||
pm.v2 = soft_dirty_cleared;
|
||||
pm.len = (PAGEMAP_WALK_SIZE >> PAGE_SHIFT);
|
||||
pm.buffer = kmalloc(pm.len * PM_ENTRY_BYTES, GFP_TEMPORARY);
|
||||
ret = -ENOMEM;
|
||||
if (!pm.buffer)
|
||||
goto out_task;
|
||||
|
||||
mm = mm_access(task, PTRACE_MODE_READ);
|
||||
ret = PTR_ERR(mm);
|
||||
if (!mm || IS_ERR(mm))
|
||||
goto out_free;
|
||||
goto out_mm;
|
||||
|
||||
pagemap_walk.pmd_entry = pagemap_pte_range;
|
||||
pagemap_walk.pte_hole = pagemap_pte_hole;
|
||||
@ -1275,10 +1268,10 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
|
||||
src = *ppos;
|
||||
svpfn = src / PM_ENTRY_BYTES;
|
||||
start_vaddr = svpfn << PAGE_SHIFT;
|
||||
end_vaddr = TASK_SIZE_OF(task);
|
||||
end_vaddr = mm->task_size;
|
||||
|
||||
/* watch out for wraparound */
|
||||
if (svpfn > TASK_SIZE_OF(task) >> PAGE_SHIFT)
|
||||
if (svpfn > mm->task_size >> PAGE_SHIFT)
|
||||
start_vaddr = end_vaddr;
|
||||
|
||||
/*
|
||||
@ -1305,7 +1298,7 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
|
||||
len = min(count, PM_ENTRY_BYTES * pm.pos);
|
||||
if (copy_to_user(buf, pm.buffer, len)) {
|
||||
ret = -EFAULT;
|
||||
goto out_mm;
|
||||
goto out_free;
|
||||
}
|
||||
copied += len;
|
||||
buf += len;
|
||||
@ -1315,24 +1308,38 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
|
||||
if (!ret || ret == PM_END_OF_BUFFER)
|
||||
ret = copied;
|
||||
|
||||
out_mm:
|
||||
mmput(mm);
|
||||
out_free:
|
||||
kfree(pm.buffer);
|
||||
out_task:
|
||||
put_task_struct(task);
|
||||
out_mm:
|
||||
mmput(mm);
|
||||
out:
|
||||
return ret;
|
||||
}
|
||||
|
||||
static int pagemap_open(struct inode *inode, struct file *file)
|
||||
{
|
||||
struct mm_struct *mm;
|
||||
|
||||
/* do not disclose physical addresses: attack vector */
|
||||
if (!capable(CAP_SYS_ADMIN))
|
||||
return -EPERM;
|
||||
pr_warn_once("Bits 55-60 of /proc/PID/pagemap entries are about "
|
||||
"to stop being page-shift some time soon. See the "
|
||||
"linux/Documentation/vm/pagemap.txt for details.\n");
|
||||
|
||||
mm = proc_mem_open(inode, PTRACE_MODE_READ);
|
||||
if (IS_ERR(mm))
|
||||
return PTR_ERR(mm);
|
||||
file->private_data = mm;
|
||||
return 0;
|
||||
}
|
||||
|
||||
static int pagemap_release(struct inode *inode, struct file *file)
|
||||
{
|
||||
struct mm_struct *mm = file->private_data;
|
||||
|
||||
if (mm)
|
||||
mmdrop(mm);
|
||||
return 0;
|
||||
}
|
||||
|
||||
@ -1340,6 +1347,7 @@ const struct file_operations proc_pagemap_operations = {
|
||||
.llseek = mem_lseek, /* borrow this */
|
||||
.read = pagemap_read,
|
||||
.open = pagemap_open,
|
||||
.release = pagemap_release,
|
||||
};
|
||||
#endif /* CONFIG_PROC_PAGE_MONITOR */
|
||||
|
||||
|
Loading…
Reference in New Issue
Block a user