rseq: Use __u64 for rseq_cs fields, validate user inputs
Change the rseq ABI so rseq_cs start_ip, post_commit_offset and abort_ip fields are seen as 64-bit fields by both 32-bit and 64-bit kernels rather that ignoring the 32 upper bits on 32-bit kernels. This ensures we have a consistent behavior for a 32-bit binary executed on 32-bit kernels and in compat mode on 64-bit kernels. Validating the value of abort_ip field to be below TASK_SIZE ensures the kernel don't return to an invalid address when returning to userspace after an abort. I don't fully trust each architecture code to consistently deal with invalid return addresses. Validating the value of the start_ip and post_commit_offset fields prevents overflow on arithmetic performed on those values, used to check whether abort_ip is within the rseq critical section. If validation fails, the process is killed with a segmentation fault. When the signature encountered before abort_ip does not match the expected signature, return -EINVAL rather than -EPERM to be consistent with other input validation return codes from rseq_get_rseq_cs(). Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Thomas 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/20180709195155.7654-2-mathieu.desnoyers@efficios.com
This commit is contained in:
parent
1e4b044d22
commit
e96d71359e
|
@ -52,10 +52,10 @@ struct rseq_cs {
|
|||
__u32 version;
|
||||
/* enum rseq_cs_flags */
|
||||
__u32 flags;
|
||||
LINUX_FIELD_u32_u64(start_ip);
|
||||
__u64 start_ip;
|
||||
/* Offset from start_ip. */
|
||||
LINUX_FIELD_u32_u64(post_commit_offset);
|
||||
LINUX_FIELD_u32_u64(abort_ip);
|
||||
__u64 post_commit_offset;
|
||||
__u64 abort_ip;
|
||||
} __attribute__((aligned(4 * sizeof(__u64))));
|
||||
|
||||
/*
|
||||
|
|
|
@ -130,14 +130,20 @@ static int rseq_get_rseq_cs(struct task_struct *t, struct rseq_cs *rseq_cs)
|
|||
urseq_cs = (struct rseq_cs __user *)ptr;
|
||||
if (copy_from_user(rseq_cs, urseq_cs, sizeof(*rseq_cs)))
|
||||
return -EFAULT;
|
||||
if (rseq_cs->version > 0)
|
||||
return -EINVAL;
|
||||
|
||||
if (rseq_cs->start_ip >= TASK_SIZE ||
|
||||
rseq_cs->start_ip + rseq_cs->post_commit_offset >= TASK_SIZE ||
|
||||
rseq_cs->abort_ip >= TASK_SIZE ||
|
||||
rseq_cs->version > 0)
|
||||
return -EINVAL;
|
||||
/* Check for overflow. */
|
||||
if (rseq_cs->start_ip + rseq_cs->post_commit_offset < rseq_cs->start_ip)
|
||||
return -EINVAL;
|
||||
/* Ensure that abort_ip is not in the critical section. */
|
||||
if (rseq_cs->abort_ip - rseq_cs->start_ip < rseq_cs->post_commit_offset)
|
||||
return -EINVAL;
|
||||
|
||||
usig = (u32 __user *)(rseq_cs->abort_ip - sizeof(u32));
|
||||
usig = (u32 __user *)(unsigned long)(rseq_cs->abort_ip - sizeof(u32));
|
||||
ret = get_user(sig, usig);
|
||||
if (ret)
|
||||
return ret;
|
||||
|
@ -146,7 +152,7 @@ static int rseq_get_rseq_cs(struct task_struct *t, struct rseq_cs *rseq_cs)
|
|||
printk_ratelimited(KERN_WARNING
|
||||
"Possible attack attempt. Unexpected rseq signature 0x%x, expecting 0x%x (pid=%d, addr=%p).\n",
|
||||
sig, current->rseq_sig, current->pid, usig);
|
||||
return -EPERM;
|
||||
return -EINVAL;
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
|
|
Loading…
Reference in a new issue