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authorAlfred Piccioni <alpic@google.com>2023-12-19 10:09:09 +0100
committerPaul Moore <paul@paul-moore.com>2023-12-24 21:48:03 +0100
commitf1bb47a31dff6d4b34fb14e99850860ee74bb003 (patch)
tree8e7e4d5a92b7a523022307678492e29085866f08 /security/selinux
parentlsm: Add a __counted_by() annotation to lsm_ctx.ctx (diff)
downloadlinux-f1bb47a31dff6d4b34fb14e99850860ee74bb003.tar.xz
linux-f1bb47a31dff6d4b34fb14e99850860ee74bb003.zip
lsm: new security_file_ioctl_compat() hook
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>
Diffstat (limited to 'security/selinux')
-rw-r--r--security/selinux/hooks.c28
1 files changed, 28 insertions, 0 deletions
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index b340425ccfae..179540441115 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3732,6 +3732,33 @@ 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)
@@ -7122,6 +7149,7 @@ 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),