[PATCH V31 25/25] debugfs: Disable open() when kernel is locked down
From: Matthew Garrett <hidden>
Date: 2019-03-26 18:29:07
Also in:
linux-security-module, lkml
Subsystem:
driver core, kobjects, debugfs and sysfs, filesystems (vfs and infrastructure), the rest · Maintainers:
Greg Kroah-Hartman, "Rafael J. Wysocki", Danilo Krummrich, Alexander Viro, Christian Brauner, Linus Torvalds
From: Matthew Garrett <redacted> debugfs has not been meaningfully audited in terms of ensuring that userland cannot trample over the kernel. At Greg's request, disable access to it entirely when the kernel is locked down. This is done at open() time rather than init time as the kernel lockdown status may be made stricter at runtime. Signed-off-by: Matthew Garrett <redacted> Cc: gregkh@linuxfoundation.org --- fs/debugfs/file.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index 4fce1da7db23..9ae12ef29ba0 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c@@ -142,6 +142,9 @@ static int open_proxy_open(struct inode *inode, struct file *filp) const struct file_operations *real_fops = NULL; int r; + if (kernel_is_locked_down("debugfs", LOCKDOWN_INTEGRITY)) + return -EPERM; + r = debugfs_file_get(dentry); if (r) return r == -EIO ? -ENOENT : r;
@@ -267,6 +270,9 @@ static int full_proxy_open(struct inode *inode, struct file *filp) struct file_operations *proxy_fops = NULL; int r; + if (kernel_is_locked_down("debugfs", LOCKDOWN_INTEGRITY)) + return -EPERM; + r = debugfs_file_get(dentry); if (r) return r == -EIO ? -ENOENT : r;
--
2.21.0.392.gf8f6787159e-goog