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 f5fd99d6b0d4ed981811797e35f254c98cd70e25..76cf22ac97d76256104a6dbc4f819247168ce769 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 2b8d85aae0832dc095a4ecc31c17e3cdc7626731..74c60f9446f8424090db420da64ddb30ae69bd01 100644 (file)
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -171,6 +171,8 @@ 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 5f16eecde00bc753ebc3066e1bb9afba0bf00905..b50c7f56618905b19192d0dbd6a040217e959a78 100644 (file)
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -389,6 +389,8 @@ 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);
@@ -987,6 +989,13 @@ 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 23b129d482a7c8f478d4fe8a709c7f4a7ed47ab8..840a3d58a29028a673adc759b631d09425d427e9 100644 (file)
--- a/security/security.c
+++ b/security/security.c
@@ -2648,6 +2648,24 @@ 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 aa0afc122f09f628c4e6cf3e5884e55b264b8bae..53cfeefb2f19425c428f6e997a61af60d94efe3f 100644 (file)
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3725,6 +3725,33 @@ 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)
@@ -7037,6 +7064,7 @@ static struct security_hook_list selinux_hooks[] __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 65130a791f5730c4f1e1eb6e442d0c31684c66ad..1f1ea8529421fd949c0c85f4bdf0e5f0d4d26b21 100644 (file)
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -4973,6 +4973,7 @@ static struct security_hook_list smack_hooks[] __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 25006fddc964b44174ac1871b497ae18df002881..298d182759c2dc1e0222b2db5391d3dd970700b6 100644 (file)
--- a/security/tomoyo/tomoyo.c
+++ b/security/tomoyo/tomoyo.c
@@ -568,6 +568,7 @@ static struct security_hook_list tomoyo_hooks[] __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),