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

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.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 11 insertions, 2 deletions

diff --git a/kernel/resource.c b/kernel/resource.c
index 2e78ead30934..9b5f04404152 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -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;
 }