From 3ddc5b46a8e90f3c9251338b60191d0a804b0d92 Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Wed, 11 Sep 2013 14:23:18 -0700 Subject: [PATCH] kernel-wide: fix missing validations on __get/__put/__copy_to/__copy_from_user() I found the following pattern that leads in to interesting findings: grep -r "ret.*|=.*__put_user" * grep -r "ret.*|=.*__get_user" * grep -r "ret.*|=.*__copy" * The __put_user() calls in compat_ioctl.c, ptrace compat, signal compat, since those appear in compat code, we could probably expect the kernel addresses not to be reachable in the lower 32-bit range, so I think they might not be exploitable. For the "__get_user" cases, I don't think those are exploitable: the worse that can happen is that the kernel will copy kernel memory into in-kernel buffers, and will fail immediately afterward. The alpha csum_partial_copy_from_user() seems to be missing the access_ok() check entirely. The fix is inspired from x86. This could lead to information leak on alpha. I also noticed that many architectures map csum_partial_copy_from_user() to csum_partial_copy_generic(), but I wonder if the latter is performing the access checks on every architectures. Signed-off-by: Mathieu Desnoyers Cc: Richard Henderson Cc: Ivan Kokshaysky Cc: Matt Turner Cc: Jens Axboe Cc: Oleg Nesterov Cc: David Miller Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/alpha/lib/csum_partial_copy.c | 5 +++ arch/sparc/kernel/sys_sparc32.c | 12 +++---- block/compat_ioctl.c | 2 +- kernel/signal.c | 4 +-- net/socket.c | 50 +++++++++++++++--------------- 5 files changed, 39 insertions(+), 34 deletions(-) diff --git a/arch/alpha/lib/csum_partial_copy.c b/arch/alpha/lib/csum_partial_copy.c index 40736da9bea8..ffb19b7da999 100644 --- a/arch/alpha/lib/csum_partial_copy.c +++ b/arch/alpha/lib/csum_partial_copy.c @@ -338,6 +338,11 @@ csum_partial_copy_from_user(const void __user *src, void *dst, int len, unsigned long doff = 7 & (unsigned long) dst; if (len) { + if (!access_ok(VERIFY_READ, src, len)) { + *errp = -EFAULT; + memset(dst, 0, len); + return sum; + } if (!doff) { if (!soff) checksum = csum_partial_cfu_aligned( diff --git a/arch/sparc/kernel/sys_sparc32.c b/arch/sparc/kernel/sys_sparc32.c index 3d0ddbc005fe..71368850dfc0 100644 --- a/arch/sparc/kernel/sys_sparc32.c +++ b/arch/sparc/kernel/sys_sparc32.c @@ -169,10 +169,10 @@ COMPAT_SYSCALL_DEFINE5(rt_sigaction, int, sig, new_ka.ka_restorer = restorer; ret = get_user(u_handler, &act->sa_handler); new_ka.sa.sa_handler = compat_ptr(u_handler); - ret |= __copy_from_user(&set32, &act->sa_mask, sizeof(compat_sigset_t)); + ret |= copy_from_user(&set32, &act->sa_mask, sizeof(compat_sigset_t)); sigset_from_compat(&new_ka.sa.sa_mask, &set32); - ret |= __get_user(new_ka.sa.sa_flags, &act->sa_flags); - ret |= __get_user(u_restorer, &act->sa_restorer); + ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags); + ret |= get_user(u_restorer, &act->sa_restorer); new_ka.sa.sa_restorer = compat_ptr(u_restorer); if (ret) return -EFAULT; @@ -183,9 +183,9 @@ COMPAT_SYSCALL_DEFINE5(rt_sigaction, int, sig, if (!ret && oact) { sigset_to_compat(&set32, &old_ka.sa.sa_mask); ret = put_user(ptr_to_compat(old_ka.sa.sa_handler), &oact->sa_handler); - ret |= __copy_to_user(&oact->sa_mask, &set32, sizeof(compat_sigset_t)); - ret |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags); - ret |= __put_user(ptr_to_compat(old_ka.sa.sa_restorer), &oact->sa_restorer); + ret |= copy_to_user(&oact->sa_mask, &set32, sizeof(compat_sigset_t)); + ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags); + ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer), &oact->sa_restorer); if (ret) ret = -EFAULT; } diff --git a/block/compat_ioctl.c b/block/compat_ioctl.c index 7e5d474dc6ba..fbd5a67cb773 100644 --- a/block/compat_ioctl.c +++ b/block/compat_ioctl.c @@ -70,7 +70,7 @@ static int compat_hdio_getgeo(struct gendisk *disk, struct block_device *bdev, return ret; ret = copy_to_user(ugeo, &geo, 4); - ret |= __put_user(geo.start, &ugeo->start); + ret |= put_user(geo.start, &ugeo->start); if (ret) ret = -EFAULT; diff --git a/kernel/signal.c b/kernel/signal.c index 50e41075ac77..ded28b91fa53 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -3394,7 +3394,7 @@ COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig, new_ka.sa.sa_restorer = compat_ptr(restorer); #endif ret |= copy_from_user(&mask, &act->sa_mask, sizeof(mask)); - ret |= __get_user(new_ka.sa.sa_flags, &act->sa_flags); + ret |= get_user(new_ka.sa.sa_flags, &act->sa_flags); if (ret) return -EFAULT; sigset_from_compat(&new_ka.sa.sa_mask, &mask); @@ -3406,7 +3406,7 @@ COMPAT_SYSCALL_DEFINE4(rt_sigaction, int, sig, ret = put_user(ptr_to_compat(old_ka.sa.sa_handler), &oact->sa_handler); ret |= copy_to_user(&oact->sa_mask, &mask, sizeof(mask)); - ret |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags); + ret |= put_user(old_ka.sa.sa_flags, &oact->sa_flags); #ifdef __ARCH_HAS_SA_RESTORER ret |= put_user(ptr_to_compat(old_ka.sa.sa_restorer), &oact->sa_restorer); diff --git a/net/socket.c b/net/socket.c index b2d7c629eeb9..0ceaa5cb9ead 100644 --- a/net/socket.c +++ b/net/socket.c @@ -3072,12 +3072,12 @@ static int compat_sioc_ifmap(struct net *net, unsigned int cmd, uifmap32 = &uifr32->ifr_ifru.ifru_map; err = copy_from_user(&ifr, uifr32, sizeof(ifr.ifr_name)); - err |= __get_user(ifr.ifr_map.mem_start, &uifmap32->mem_start); - err |= __get_user(ifr.ifr_map.mem_end, &uifmap32->mem_end); - err |= __get_user(ifr.ifr_map.base_addr, &uifmap32->base_addr); - err |= __get_user(ifr.ifr_map.irq, &uifmap32->irq); - err |= __get_user(ifr.ifr_map.dma, &uifmap32->dma); - err |= __get_user(ifr.ifr_map.port, &uifmap32->port); + err |= get_user(ifr.ifr_map.mem_start, &uifmap32->mem_start); + err |= get_user(ifr.ifr_map.mem_end, &uifmap32->mem_end); + err |= get_user(ifr.ifr_map.base_addr, &uifmap32->base_addr); + err |= get_user(ifr.ifr_map.irq, &uifmap32->irq); + err |= get_user(ifr.ifr_map.dma, &uifmap32->dma); + err |= get_user(ifr.ifr_map.port, &uifmap32->port); if (err) return -EFAULT; @@ -3088,12 +3088,12 @@ static int compat_sioc_ifmap(struct net *net, unsigned int cmd, if (cmd == SIOCGIFMAP && !err) { err = copy_to_user(uifr32, &ifr, sizeof(ifr.ifr_name)); - err |= __put_user(ifr.ifr_map.mem_start, &uifmap32->mem_start); - err |= __put_user(ifr.ifr_map.mem_end, &uifmap32->mem_end); - err |= __put_user(ifr.ifr_map.base_addr, &uifmap32->base_addr); - err |= __put_user(ifr.ifr_map.irq, &uifmap32->irq); - err |= __put_user(ifr.ifr_map.dma, &uifmap32->dma); - err |= __put_user(ifr.ifr_map.port, &uifmap32->port); + err |= put_user(ifr.ifr_map.mem_start, &uifmap32->mem_start); + err |= put_user(ifr.ifr_map.mem_end, &uifmap32->mem_end); + err |= put_user(ifr.ifr_map.base_addr, &uifmap32->base_addr); + err |= put_user(ifr.ifr_map.irq, &uifmap32->irq); + err |= put_user(ifr.ifr_map.dma, &uifmap32->dma); + err |= put_user(ifr.ifr_map.port, &uifmap32->port); if (err) err = -EFAULT; } @@ -3167,25 +3167,25 @@ static int routing_ioctl(struct net *net, struct socket *sock, struct in6_rtmsg32 __user *ur6 = argp; ret = copy_from_user(&r6.rtmsg_dst, &(ur6->rtmsg_dst), 3 * sizeof(struct in6_addr)); - ret |= __get_user(r6.rtmsg_type, &(ur6->rtmsg_type)); - ret |= __get_user(r6.rtmsg_dst_len, &(ur6->rtmsg_dst_len)); - ret |= __get_user(r6.rtmsg_src_len, &(ur6->rtmsg_src_len)); - ret |= __get_user(r6.rtmsg_metric, &(ur6->rtmsg_metric)); - ret |= __get_user(r6.rtmsg_info, &(ur6->rtmsg_info)); - ret |= __get_user(r6.rtmsg_flags, &(ur6->rtmsg_flags)); - ret |= __get_user(r6.rtmsg_ifindex, &(ur6->rtmsg_ifindex)); + ret |= get_user(r6.rtmsg_type, &(ur6->rtmsg_type)); + ret |= get_user(r6.rtmsg_dst_len, &(ur6->rtmsg_dst_len)); + ret |= get_user(r6.rtmsg_src_len, &(ur6->rtmsg_src_len)); + ret |= get_user(r6.rtmsg_metric, &(ur6->rtmsg_metric)); + ret |= get_user(r6.rtmsg_info, &(ur6->rtmsg_info)); + ret |= get_user(r6.rtmsg_flags, &(ur6->rtmsg_flags)); + ret |= get_user(r6.rtmsg_ifindex, &(ur6->rtmsg_ifindex)); r = (void *) &r6; } else { /* ipv4 */ struct rtentry32 __user *ur4 = argp; ret = copy_from_user(&r4.rt_dst, &(ur4->rt_dst), 3 * sizeof(struct sockaddr)); - ret |= __get_user(r4.rt_flags, &(ur4->rt_flags)); - ret |= __get_user(r4.rt_metric, &(ur4->rt_metric)); - ret |= __get_user(r4.rt_mtu, &(ur4->rt_mtu)); - ret |= __get_user(r4.rt_window, &(ur4->rt_window)); - ret |= __get_user(r4.rt_irtt, &(ur4->rt_irtt)); - ret |= __get_user(rtdev, &(ur4->rt_dev)); + ret |= get_user(r4.rt_flags, &(ur4->rt_flags)); + ret |= get_user(r4.rt_metric, &(ur4->rt_metric)); + ret |= get_user(r4.rt_mtu, &(ur4->rt_mtu)); + ret |= get_user(r4.rt_window, &(ur4->rt_window)); + ret |= get_user(r4.rt_irtt, &(ur4->rt_irtt)); + ret |= get_user(rtdev, &(ur4->rt_dev)); if (rtdev) { ret |= copy_from_user(devname, compat_ptr(rtdev), 15); r4.rt_dev = (char __user __force *)devname; -- 2.20.1