• Mathieu Desnoyers's avatar
    rseq: uapi: Declare rseq_cs field as union, update includes · ec9c82e0
    Mathieu Desnoyers authored
    Declaring the rseq_cs field as a union between __u64 and two __u32
    allows both 32-bit and 64-bit kernels to read the full __u64, and
    therefore validate that a 32-bit user-space cleared the upper 32
    bits, thus ensuring a consistent behavior between native 32-bit
    kernels and 32-bit compat tasks on 64-bit kernels.
    
    Check that the rseq_cs value read is < TASK_SIZE.
    
    The asm/byteorder.h header needs to be included by rseq.h, now
    that it is not using linux/types_32_64.h anymore.
    
    Considering that only __32 and __u64 types are declared in linux/rseq.h,
    the linux/types.h header should always be included for both kernel and
    user-space code: including stdint.h is just for u64 and u32, which are
    not used in this header at all.
    
    Use copy_from_user()/clear_user() to interact with a 64-bit field,
    because arm32 does not implement 64-bit __get_user, and ppc32 does not
    64-bit get_user. Considering that the rseq_cs pointer does not need to
    be loaded/stored with single-copy atomicity from the kernel anymore, we
    can simply use copy_from_user()/clear_user().
    Signed-off-by: default avatarMathieu Desnoyers <mathieu.desnoyers@efficios.com>
    Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Cc: linux-api@vger.kernel.org
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>
    Cc: Boqun Feng <boqun.feng@gmail.com>
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: Dave Watson <davejwatson@fb.com>
    Cc: Paul Turner <pjt@google.com>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Russell King <linux@arm.linux.org.uk>
    Cc: "H . Peter Anvin" <hpa@zytor.com>
    Cc: Andi Kleen <andi@firstfloor.org>
    Cc: Chris Lameter <cl@linux.com>
    Cc: Ben Maurer <bmaurer@fb.com>
    Cc: Steven Rostedt <rostedt@goodmis.org>
    Cc: Josh Triplett <josh@joshtriplett.org>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: Will Deacon <will.deacon@arm.com>
    Cc: Michael Kerrisk <mtk.manpages@gmail.com>
    Cc: Joel Fernandes <joelaf@google.com>
    Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
    Cc: "H. Peter Anvin" <hpa@zytor.com>
    Link: https://lkml.kernel.org/r/20180709195155.7654-5-mathieu.desnoyers@efficios.com
    ec9c82e0