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/proc/iomem: only expose physical resource addresses to privileged users

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commit 51d7b120418e99d6b3bf8df9eb3cc31e8171dee4 upstream.

In commit c4004b02f8e5b ("x86: remove the kernel code/data/bss resources
from /proc/iomem") I was hoping to remove the phyiscal kernel address
data from /proc/iomem entirely, but that had to be reverted because some
system programs actually use it.

This limits all the detailed resource information to properly
credentialed users instead.

[sumits: this is used in Ubuntu as a fix for CVE-2015-8944]

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Linus Torvalds 2016-04-14 12:05:37 -07:00 committed by Greg Kroah-Hartman
parent 14ae9c4b5a
commit e8aff60373
1 changed files with 11 additions and 2 deletions
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13
kernel/resource.c
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@ -105,16 +105,25 @@ static int r_show(struct seq_file *m, void *v)
{
struct resource *root = m->private;
struct resource *r = v, *p;
unsigned long long start, end;
int width = root->end < 0x10000 ? 4 : 8;
int depth;
for (depth = 0, p = r; depth < MAX_IORES_LEVEL; depth++, p = p->parent)
if (p->parent == root)
break;
if (file_ns_capable(m->file, &init_user_ns, CAP_SYS_ADMIN)) {
start = r->start;
end = r->end;
} else {
start = end = 0;
}
seq_printf(m, "%*s%0*llx-%0*llx : %s\n",
depth * 2, "",
width, (unsigned long long) r->start,
width, (unsigned long long) r->end,
width, start,
width, end,
r->name ? r->name : "<BAD>");
return 0;
}