lsm: new security_file_ioctl_compat() hook

commit f1bb47a31dff6d4b34fb14e99850860ee74bb003 upstream.

Some ioctl commands do not require ioctl permission, but are routed to
other permissions such as FILE_GETATTR or FILE_SETATTR. This routing is
done by comparing the ioctl cmd to a set of 64-bit flags (FS_IOC_*).

However, if a 32-bit process is running on a 64-bit kernel, it emits
32-bit flags (FS_IOC32_*) for certain ioctl operations. These flags are
being checked erroneously, which leads to these ioctl operations being
routed to the ioctl permission, rather than the correct file
permissions.

This was also noted in a RED-PEN finding from a while back -
"/* RED-PEN how should LSM module know it's handling 32bit? */".

This patch introduces a new hook, security_file_ioctl_compat(), that is
called from the compat ioctl syscall. All current LSMs have been changed
to support this hook.

Reviewing the three places where we are currently using
security_file_ioctl(), it appears that only SELinux needs a dedicated
compat change; TOMOYO and SMACK appear to be functional without any
change.

Cc: stable@vger.kernel.org
Fixes: 0b24dcb7f2f7 ("Revert "selinux: simplify ioctl checking"")
Signed-off-by: Alfred Piccioni <alpic@google.com>
Reviewed-by: Stephen Smalley <stephen.smalley.work@gmail.com>
[PM: subject tweak, line length fixes, and alignment corrections]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/ioctl.c b/fs/ioctl.c
index e0a3455f9a0f6160df7705bf48d3a7d125557d27..5b0ab4ad1772a464e2ea0b3aa5222309f1608cb2 100644 (file)
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -920,8 +920,7 @@ COMPAT_SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd,
        if (!f.file)
                return -EBADF;
 
-       /* RED-PEN how should LSM module know it's handling 32bit? */
-       error = security_file_ioctl(f.file, cmd, arg);
+       error = security_file_ioctl_compat(f.file, cmd, arg);
        if (error)
                goto out;
 

diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index c4f245262f9877b649b53828234bee14eb9a416e..af2fa1134b506b9d8f0e23f9cfbf4ca2547ada40 100644 (file)
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -165,6 +165,8 @@ LSM_HOOK(int, 0, file_alloc_security, struct file *file)
 LSM_HOOK(void, LSM_RET_VOID, file_free_security, struct file *file)
 LSM_HOOK(int, 0, file_ioctl, struct file *file, unsigned int cmd,
         unsigned long arg)
+LSM_HOOK(int, 0, file_ioctl_compat, struct file *file, unsigned int cmd,
+        unsigned long arg)
 LSM_HOOK(int, 0, mmap_addr, unsigned long addr)
 LSM_HOOK(int, 0, mmap_file, struct file *file, unsigned long reqprot,
         unsigned long prot, unsigned long flags)

diff --git a/include/linux/security.h b/include/linux/security.h
index da184e7b361f4c184ba68fac18bab0d67080f574..e844834db698678365e6bc5c8fa81dbf05629126 100644 (file)
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -382,6 +382,8 @@ int security_file_permission(struct file *file, int mask);
 int security_file_alloc(struct file *file);
 void security_file_free(struct file *file);
 int security_file_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
+int security_file_ioctl_compat(struct file *file, unsigned int cmd,
+                              unsigned long arg);
 int security_mmap_file(struct file *file, unsigned long prot,
                        unsigned long flags);
 int security_mmap_addr(unsigned long addr);
@@ -963,6 +965,13 @@ static inline int security_file_ioctl(struct file *file, unsigned int cmd,
        return 0;
 }
 
+static inline int security_file_ioctl_compat(struct file *file,
+                                            unsigned int cmd,
+                                            unsigned long arg)
+{
+       return 0;
+}
+
 static inline int security_mmap_file(struct file *file, unsigned long prot,
                                     unsigned long flags)
 {

diff --git a/security/security.c b/security/security.c
index a97079e12c67460cc43ea6aaff4c80337af333f7..aa12590f69e0e9198bba8be5e2d7ddcfcbaca715 100644 (file)
--- a/security/security.c
+++ b/security/security.c
@@ -1556,6 +1556,24 @@ int security_file_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 }
 EXPORT_SYMBOL_GPL(security_file_ioctl);
 
+/**
+ * security_file_ioctl_compat() - Check if an ioctl is allowed in compat mode
+ * @file: associated file
+ * @cmd: ioctl cmd
+ * @arg: ioctl arguments
+ *
+ * Compat version of security_file_ioctl() that correctly handles 32-bit
+ * processes running on 64-bit kernels.
+ *
+ * Return: Returns 0 if permission is granted.
+ */
+int security_file_ioctl_compat(struct file *file, unsigned int cmd,
+                              unsigned long arg)
+{
+       return call_int_hook(file_ioctl_compat, 0, file, cmd, arg);
+}
+EXPORT_SYMBOL_GPL(security_file_ioctl_compat);
+
 static inline unsigned long mmap_prot(struct file *file, unsigned long prot)
 {
        /*

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index ec839716dbac2f40b48ada5de154b7246c71180e..d9a680792b21675a80b99f92d42f815619d44ace 100644 (file)
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3810,6 +3810,33 @@ static int selinux_file_ioctl(struct file *file, unsigned int cmd,
        return error;
 }
 
+static int selinux_file_ioctl_compat(struct file *file, unsigned int cmd,
+                             unsigned long arg)
+{
+       /*
+        * If we are in a 64-bit kernel running 32-bit userspace, we need to
+        * make sure we don't compare 32-bit flags to 64-bit flags.
+        */
+       switch (cmd) {
+       case FS_IOC32_GETFLAGS:
+               cmd = FS_IOC_GETFLAGS;
+               break;
+       case FS_IOC32_SETFLAGS:
+               cmd = FS_IOC_SETFLAGS;
+               break;
+       case FS_IOC32_GETVERSION:
+               cmd = FS_IOC_GETVERSION;
+               break;
+       case FS_IOC32_SETVERSION:
+               cmd = FS_IOC_SETVERSION;
+               break;
+       default:
+               break;
+       }
+
+       return selinux_file_ioctl(file, cmd, arg);
+}
+
 static int default_noexec __ro_after_init;
 
 static int file_map_prot_check(struct file *file, unsigned long prot, int shared)
@@ -7208,6 +7235,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
        LSM_HOOK_INIT(file_permission, selinux_file_permission),
        LSM_HOOK_INIT(file_alloc_security, selinux_file_alloc_security),
        LSM_HOOK_INIT(file_ioctl, selinux_file_ioctl),
+       LSM_HOOK_INIT(file_ioctl_compat, selinux_file_ioctl_compat),
        LSM_HOOK_INIT(mmap_file, selinux_mmap_file),
        LSM_HOOK_INIT(mmap_addr, selinux_mmap_addr),
        LSM_HOOK_INIT(file_mprotect, selinux_file_mprotect),

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 39f564f47fea55cce9952cbb99289be78de005cf..a5a78aef6403acc0239b9c4d584dfdc8c241e78f 100644 (file)
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -4767,6 +4767,7 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
 
        LSM_HOOK_INIT(file_alloc_security, smack_file_alloc_security),
        LSM_HOOK_INIT(file_ioctl, smack_file_ioctl),
+       LSM_HOOK_INIT(file_ioctl_compat, smack_file_ioctl),
        LSM_HOOK_INIT(file_lock, smack_file_lock),
        LSM_HOOK_INIT(file_fcntl, smack_file_fcntl),
        LSM_HOOK_INIT(mmap_file, smack_mmap_file),

diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c
index b6a31901f289477793b29af2456cd3ee18b225e0..1be96e2ce9f1afe5bb33fbeb0c3a2a168ec8d4aa 100644 (file)
--- a/security/tomoyo/tomoyo.c
+++ b/security/tomoyo/tomoyo.c
@@ -546,6 +546,7 @@ static struct security_hook_list tomoyo_hooks[] __lsm_ro_after_init = {
        LSM_HOOK_INIT(path_rename, tomoyo_path_rename),
        LSM_HOOK_INIT(inode_getattr, tomoyo_inode_getattr),
        LSM_HOOK_INIT(file_ioctl, tomoyo_file_ioctl),
+       LSM_HOOK_INIT(file_ioctl_compat, tomoyo_file_ioctl),
        LSM_HOOK_INIT(path_chmod, tomoyo_path_chmod),
        LSM_HOOK_INIT(path_chown, tomoyo_path_chown),
        LSM_HOOK_INIT(path_chroot, tomoyo_path_chroot),