From: Matthew Garrett <matthewgarrett@google.com>
To: jmorris@namei.org
Cc: linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org, dhowells@redhat.com,
linux-api@vger.kernel.org, luto@kernel.org,
Matthew Garrett <matthewgarrett@google.com>,
Matthew Garrett <mjg59@google.com>,
Steven Rostedt <rostedt@goodmis.org>
Subject: [PATCH V32 27/27] tracefs: Restrict tracefs when the kernel is locked down
Date: Wed, 3 Apr 2019 17:32:49 -0700 [thread overview]
Message-ID: <20190404003249.14356-28-matthewgarrett@google.com> (raw)
In-Reply-To: <20190404003249.14356-1-matthewgarrett@google.com>
Tracefs may release more information about the kernel than desirable, so
restrict it when the kernel is locked down in confidentiality mode by
preventing open().
Signed-off-by: Matthew Garrett <mjg59@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
---
fs/tracefs/inode.c | 40 +++++++++++++++++++++++++++++++++++++++-
1 file changed, 39 insertions(+), 1 deletion(-)
diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index 7098c49f3693..576327ffd9d1 100644
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -31,6 +31,21 @@ static struct vfsmount *tracefs_mount;
static int tracefs_mount_count;
static bool tracefs_registered;
+static int default_open_file(struct inode *inode, struct file *filp)
+{
+ struct dentry *dentry = filp->f_path.dentry;
+ struct file_operations *real_fops;
+
+ if (!dentry)
+ return -EINVAL;
+
+ if (kernel_is_locked_down("tracefs", LOCKDOWN_CONFIDENTIALITY))
+ return -EPERM;
+
+ real_fops = dentry->d_fsdata;
+ return real_fops->open(inode, filp);
+}
+
static ssize_t default_read_file(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
@@ -50,6 +65,13 @@ static const struct file_operations tracefs_file_operations = {
.llseek = noop_llseek,
};
+static const struct file_operations tracefs_proxy_file_operations = {
+ .read = default_read_file,
+ .write = default_write_file,
+ .open = default_open_file,
+ .llseek = noop_llseek,
+};
+
static struct tracefs_dir_ops {
int (*mkdir)(const char *name);
int (*rmdir)(const char *name);
@@ -225,6 +247,12 @@ static int tracefs_apply_options(struct super_block *sb)
return 0;
}
+static void tracefs_destroy_inode(struct inode *inode)
+{
+ if S_ISREG(inode->i_mode)
+ kfree(inode->i_fop);
+}
+
static int tracefs_remount(struct super_block *sb, int *flags, char *data)
{
int err;
@@ -260,6 +288,7 @@ static int tracefs_show_options(struct seq_file *m, struct dentry *root)
static const struct super_operations tracefs_super_operations = {
.statfs = simple_statfs,
+ .destroy_inode = tracefs_destroy_inode,
.remount_fs = tracefs_remount,
.show_options = tracefs_show_options,
};
@@ -393,6 +422,7 @@ struct dentry *tracefs_create_file(const char *name, umode_t mode,
{
struct dentry *dentry;
struct inode *inode;
+ struct file_operations *proxy_fops;
if (!(mode & S_IFMT))
mode |= S_IFREG;
@@ -406,8 +436,16 @@ struct dentry *tracefs_create_file(const char *name, umode_t mode,
if (unlikely(!inode))
return failed_creating(dentry);
+ proxy_fops = kzalloc(sizeof(struct file_operations), GFP_KERNEL);
+ if (!proxy_fops)
+ return failed_creating(dentry);
+
+ dentry->d_fsdata = fops ? (void *)fops :
+ (void *)&tracefs_file_operations;
+ memcpy(proxy_fops, dentry->d_fsdata, sizeof(struct file_operations));
+ proxy_fops->open = default_open_file;
inode->i_mode = mode;
- inode->i_fop = fops ? fops : &tracefs_file_operations;
+ inode->i_fop = proxy_fops;
inode->i_private = data;
d_instantiate(dentry, inode);
fsnotify_create(dentry->d_parent->d_inode, dentry);
--
2.21.0.392.gf8f6787159e-goog
next prev parent reply other threads:[~2019-04-04 0:34 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-04 0:32 [PATCH V32 0/27] Lockdown patches for 5.2 Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 01/27] Add the ability to lock down access to the running kernel image Matthew Garrett
2019-04-16 8:40 ` Andrew Donnellan
2019-04-18 6:38 ` Daniel Axtens
2019-04-18 19:35 ` Matthew Garrett
2019-04-29 0:06 ` Daniel Axtens
2019-04-29 4:54 ` Daniel Axtens
2019-04-30 5:15 ` Andrew Donnellan
2019-04-29 22:56 ` Matthew Garrett
2019-05-02 21:07 ` James Morris
2019-05-02 21:15 ` Matthew Garrett
2019-05-02 23:19 ` James Morris
2019-05-03 0:34 ` Andy Lutomirski
2019-04-04 0:32 ` [PATCH V32 02/27] Enforce module signatures if the kernel is locked down Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 03/27] Restrict /dev/{mem,kmem,port} when " Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 04/27] kexec_load: Disable at runtime if " Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 05/27] Copy secure_boot flag in boot params across kexec reboot Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 06/27] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 07/27] kexec_file: Restrict at runtime if the kernel is locked down Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 08/27] hibernate: Disable when " Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 09/27] uswsusp: " Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 10/27] PCI: Lock down BAR access " Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 11/27] x86: Lock down IO port " Matthew Garrett
2019-04-04 7:49 ` Thomas Gleixner
2019-04-04 0:32 ` [PATCH V32 12/27] x86/msr: Restrict MSR " Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 13/27] ACPI: Limit access to custom_method " Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 14/27] acpi: Ignore acpi_rsdp kernel param when the kernel has been " Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 15/27] acpi: Disable ACPI table override if the kernel is " Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 16/27] Prohibit PCMCIA CIS storage when " Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 17/27] Lock down TIOCSSERIAL Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 18/27] Lock down module params that specify hardware parameters (eg. ioport) Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 19/27] x86/mmiotrace: Lock down the testmmiotrace module Matthew Garrett
2019-04-04 1:33 ` Steven Rostedt
2019-04-04 7:47 ` Thomas Gleixner
2019-04-04 0:32 ` [PATCH V32 20/27] Lock down /proc/kcore Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 21/27] Lock down tracing and perf kprobes when in confidentiality mode Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 22/27] bpf: Restrict bpf when kernel lockdown is " Matthew Garrett
2019-04-30 19:19 ` Jann Horn
2019-04-04 0:32 ` [PATCH V32 23/27] Lock down perf when " Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 24/27] kexec: Allow kexec_file() with appropriate IMA policy when locked down Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 25/27] lockdown: Print current->comm in restriction messages Matthew Garrett
2019-04-04 0:32 ` [PATCH V32 26/27] debugfs: Restrict debugfs when the kernel is locked down Matthew Garrett
2019-04-04 0:32 ` Matthew Garrett [this message]
2019-04-04 13:39 ` [PATCH V32 27/27] tracefs: Restrict tracefs " Steven Rostedt
2019-04-04 20:09 ` Matthew Garrett
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