user/sven/linux.git/include, branch v3.12.59

crypto: crypto_memneq - add equality testing of memory regions w/o timing leaks

2016-04-23T07:24:42Z

commit 6bf37e5aa90f18baf5acf4874bca505dd667c37f upstream. When comparing MAC hashes, AEAD authentication tags, or other hash values in the context of authentication or integrity checking, it is important not to leak timing information to a potential attacker, i.e. when communication happens over a network. Bytewise memory comparisons (such as memcmp) are usually optimized so that they return a nonzero value as soon as a mismatch is found. E.g, on x86_64/i5 for 512 bytes this can be ~50 cyc for a full mismatch and up to ~850 cyc for a full match (cold). This early-return behavior can leak timing information as a side channel, allowing an attacker to iteratively guess the correct result. This patch adds a new method crypto_memneq ("memory not equal to each other") to the crypto API that compares memory areas of the same length in roughly "constant time" (cache misses could change the timing, but since they don't reveal information about the content of the strings being compared, they are effectively benign). Iow, best and worst case behaviour take the same amount of time to complete (in contrast to memcmp). Note that crypto_memneq (unlike memcmp) can only be used to test for equality or inequality, NOT for lexicographical order. This, however, is not an issue for its use-cases within the crypto API. We tried to locate all of the places in the crypto API where memcmp was being used for authentication or integrity checking, and convert them over to crypto_memneq. crypto_memneq is declared noinline, placed in its own source file, and compiled with optimizations that might increase code size disabled ("Os") because a smart compiler (or LTO) might notice that the return value is always compared against zero/nonzero, and might then reintroduce the same early-return optimization that we are trying to avoid. Using #pragma or __attribute__ optimization annotations of the code for disabling optimization was avoided as it seems to be considered broken or unmaintained for long time in GCC [1]. Therefore, we work around that by specifying the compile flag for memneq.o directly in the Makefile. We found that this seems to be most appropriate. As we use ("Os"), this patch also provides a loop-free "fast-path" for frequently used 16 byte digests. Similarly to kernel library string functions, leave an option for future even further optimized architecture specific assembler implementations. This was a joint work of James Yonan and Daniel Borkmann. Also thanks for feedback from Florian Weimer on this and earlier proposals [2]. [1] http://gcc.gnu.org/ml/gcc/2012-07/msg00211.html [2] https://lkml.org/lkml/2013/2/10/131 Signed-off-by: James Yonan Signed-off-by: Daniel Borkmann Cc: Florian Weimer Signed-off-by: Herbert Xu Signed-off-by: Jiri Slaby

pipe: limit the per-user amount of pages allocated in pipes

2016-04-21T11:11:54Z

commit 759c01142a5d0f364a462346168a56de28a80f52 upstream. On no-so-small systems, it is possible for a single process to cause an OOM condition by filling large pipes with data that are never read. A typical process filling 4000 pipes with 1 MB of data will use 4 GB of memory. On small systems it may be tricky to set the pipe max size to prevent this from happening. This patch makes it possible to enforce a per-user soft limit above which new pipes will be limited to a single page, effectively limiting them to 4 kB each, as well as a hard limit above which no new pipes may be created for this user. This has the effect of protecting the system against memory abuse without hurting other users, and still allowing pipes to work correctly though with less data at once. The limit are controlled by two new sysctls : pipe-user-pages-soft, and pipe-user-pages-hard. Both may be disabled by setting them to zero. The default soft limit allows the default number of FDs per process (1024) to create pipes of the default size (64kB), thus reaching a limit of 64MB before starting to create only smaller pipes. With 256 processes limited to 1024 FDs each, this results in 1024*64kB + (256*1024 - 1024) * 4kB = 1084 MB of memory allocated for a user. The hard limit is disabled by default to avoid breaking existing applications that make intensive use of pipes (eg: for splicing). Reported-by: socketpair@gmail.com Reported-by: Tetsuo Handa Mitigates: CVE-2013-4312 (Linux 2.0+) Suggested-by: Linus Torvalds Signed-off-by: Willy Tarreau Signed-off-by: Al Viro Signed-off-by: Jiri Slaby

tracing: Fix trace_printk() to print when not using bprintk()

2016-04-11T14:44:23Z

commit 3debb0a9ddb16526de8b456491b7db60114f7b5e upstream. The trace_printk() code will allocate extra buffers if the compile detects that a trace_printk() is used. To do this, the format of the trace_printk() is saved to the __trace_printk_fmt section, and if that section is bigger than zero, the buffers are allocated (along with a message that this has happened). If trace_printk() uses a format that is not a constant, and thus something not guaranteed to be around when the print happens, the compiler optimizes the fmt out, as it is not used, and the __trace_printk_fmt section is not filled. This means the kernel will not allocate the special buffers needed for the trace_printk() and the trace_printk() will not write anything to the tracing buffer. Adding a "__used" to the variable in the __trace_printk_fmt section will keep it around, even though it is set to NULL. This will keep the string from being printed in the debugfs/tracing/printk_formats section as it is not needed. Reported-by: Vlastimil Babka Fixes: 07d777fe8c398 "tracing: Add percpu buffers for trace_printk()" Signed-off-by: Steven Rostedt Signed-off-by: Jiri Slaby

fs/coredump: prevent fsuid=0 dumps into user-controlled directories

2016-04-11T14:44:20Z

commit 378c6520e7d29280f400ef2ceaf155c86f05a71a upstream. This commit fixes the following security hole affecting systems where all of the following conditions are fulfilled: - The fs.suid_dumpable sysctl is set to 2. - The kernel.core_pattern sysctl's value starts with "/". (Systems where kernel.core_pattern starts with "|/" are not affected.) - Unprivileged user namespace creation is permitted. (This is true on Linux >=3.8, but some distributions disallow it by default using a distro patch.) Under these conditions, if a program executes under secure exec rules, causing it to run with the SUID_DUMP_ROOT flag, then unshares its user namespace, changes its root directory and crashes, the coredump will be written using fsuid=0 and a path derived from kernel.core_pattern - but this path is interpreted relative to the root directory of the process, allowing the attacker to control where a coredump will be written with root privileges. To fix the security issue, always interpret core_pattern for dumps that are written under SUID_DUMP_ROOT relative to the root directory of init. Signed-off-by: Jann Horn Acked-by: Kees Cook Cc: Al Viro Cc: "Eric W. Biederman" Cc: Andy Lutomirski Cc: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Jiri Slaby

PCI: Disable IO/MEM decoding for devices with non-compliant BARs

2016-04-11T14:44:00Z

commit b84106b4e2290c081cdab521fa832596cdfea246 upstream. The PCI config header (first 64 bytes of each device's config space) is defined by the PCI spec so generic software can identify the device and manage its usage of I/O, memory, and IRQ resources. Some non-spec-compliant devices put registers other than BARs where the BARs should be. When the PCI core sizes these "BARs", the reads and writes it does may have unwanted side effects, and the "BAR" may appear to describe non-sensical address space. Add a flag bit to mark non-compliant devices so we don't touch their BARs. Turn off IO/MEM decoding to prevent the devices from consuming address space, since we can't read the BARs to find out what that address space would be. Signed-off-by: Bjorn Helgaas Tested-by: Andi Kleen Signed-off-by: Jiri Slaby

mld, igmp: Fix reserved tailroom calculation

2016-04-11T14:43:57Z

commit 1837b2e2bcd23137766555a63867e649c0b637f0 upstream. The current reserved_tailroom calculation fails to take hlen and tlen into account. skb: [__hlen__|__data____________|__tlen___|__extra__] ^ ^ head skb_end_offset In this representation, hlen + data + tlen is the size passed to alloc_skb. "extra" is the extra space made available in __alloc_skb because of rounding up by kmalloc. We can reorder the representation like so: [__hlen__|__data____________|__extra__|__tlen___] ^ ^ head skb_end_offset The maximum space available for ip headers and payload without fragmentation is min(mtu, data + extra). Therefore, reserved_tailroom = data + extra + tlen - min(mtu, data + extra) = skb_end_offset - hlen - min(mtu, skb_end_offset - hlen - tlen) = skb_tailroom - min(mtu, skb_tailroom - tlen) ; after skb_reserve(hlen) Compare the second line to the current expression: reserved_tailroom = skb_end_offset - min(mtu, skb_end_offset) and we can see that hlen and tlen are not taken into account. The min() in the third line can be expanded into: if mtu < skb_tailroom - tlen: reserved_tailroom = skb_tailroom - mtu else: reserved_tailroom = tlen Depending on hlen, tlen, mtu and the number of multicast address records, the current code may output skbs that have less tailroom than dev->needed_tailroom or it may output more skbs than needed because not all space available is used. Fixes: 4c672e4b ("ipv6: mld: fix add_grhead skb_over_panic for devs with large MTUs") Signed-off-by: Benjamin Poirier Acked-by: Hannes Frederic Sowa Acked-by: Daniel Borkmann Signed-off-by: David S. Miller Signed-off-by: Jiri Slaby

net/ipv6: fix DEVCONF_ constants

2016-04-11T14:43:56Z

In 3.12 commit e16f537864eb9cf68683d9e107706d1b31fcaa76 (net/ipv6: add sysctl option accept_ra_min_hop_limit), upstream commit 8013d1d7eafb0589ca766db6b74026f76b7f5cb4, we added DEVCONF_USE_OIF_ADDRS_ONLY and DEVCONF_ACCEPT_RA_MIN_HOP_LIMIT constants into . But they have different values to upstream because some values were added in upstream and we did not backport them. So we have: DEVCONF_SUPPRESS_FRAG_NDISC, + DEVCONF_USE_OIF_ADDRS_ONLY, + DEVCONF_ACCEPT_RA_MIN_HOP_LIMIT, DEVCONF_MAX And upstream has: DEVCONF_SUPPRESS_FRAG_NDISC, + DEVCONF_ACCEPT_RA_FROM_LOCAL, + DEVCONF_USE_OPTIMISTIC, + DEVCONF_ACCEPT_RA_MTU, + DEVCONF_STABLE_SECRET, + DEVCONF_USE_OIF_ADDRS_ONLY, + DEVCONF_ACCEPT_RA_MIN_HOP_LIMIT, DEVCONF_MAX Now, our DEVCONF_USE_OIF_ADDRS_ONLY corresponds to DEVCONF_USE_OIF_ADDRS_ONLY-4 == DEVCONF_ACCEPT_RA_FROM_LOCAL from upstream. Similarly the other constant. Fix that by simply defining the missing constants to make the values equal. Signed-off-by: Jiri Slaby Reported-by: YOSHIFUJI Hideaki Cc: Luis Henriques Cc: David S. Miller Cc: Hangbin Liu

ALSA: rawmidi: Make snd_rawmidi_transmit() race-free

2016-04-11T14:43:51Z

commit 06ab30034ed9c200a570ab13c017bde248ddb2a6 upstream. A kernel WARNING in snd_rawmidi_transmit_ack() is triggered by syzkaller fuzzer: WARNING: CPU: 1 PID: 20739 at sound/core/rawmidi.c:1136 Call Trace: [< inline >] __dump_stack lib/dump_stack.c:15 [] dump_stack+0x6f/0xa2 lib/dump_stack.c:50 [] warn_slowpath_common+0xd9/0x140 kernel/panic.c:482 [] warn_slowpath_null+0x29/0x30 kernel/panic.c:515 [] snd_rawmidi_transmit_ack+0x275/0x400 sound/core/rawmidi.c:1136 [] snd_virmidi_output_trigger+0x4b1/0x5a0 sound/core/seq/seq_virmidi.c:163 [< inline >] snd_rawmidi_output_trigger sound/core/rawmidi.c:150 [] snd_rawmidi_kernel_write1+0x549/0x780 sound/core/rawmidi.c:1223 [] snd_rawmidi_write+0x543/0xb30 sound/core/rawmidi.c:1273 [] __vfs_write+0x113/0x480 fs/read_write.c:528 [] vfs_write+0x167/0x4a0 fs/read_write.c:577 [< inline >] SYSC_write fs/read_write.c:624 [] SyS_write+0x111/0x220 fs/read_write.c:616 [] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185 Also a similar warning is found but in another path: Call Trace: [< inline >] __dump_stack lib/dump_stack.c:15 [] dump_stack+0x6f/0xa2 lib/dump_stack.c:50 [] warn_slowpath_common+0xd9/0x140 kernel/panic.c:482 [] warn_slowpath_null+0x29/0x30 kernel/panic.c:515 [] rawmidi_transmit_ack+0x24a/0x3b0 sound/core/rawmidi.c:1133 [] snd_rawmidi_transmit_ack+0x51/0x80 sound/core/rawmidi.c:1163 [] snd_virmidi_output_trigger+0x2b6/0x570 sound/core/seq/seq_virmidi.c:185 [< inline >] snd_rawmidi_output_trigger sound/core/rawmidi.c:150 [] snd_rawmidi_kernel_write1+0x4bb/0x760 sound/core/rawmidi.c:1252 [] snd_rawmidi_write+0x543/0xb30 sound/core/rawmidi.c:1302 [] __vfs_write+0x113/0x480 fs/read_write.c:528 [] vfs_write+0x167/0x4a0 fs/read_write.c:577 [< inline >] SYSC_write fs/read_write.c:624 [] SyS_write+0x111/0x220 fs/read_write.c:616 [] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185 In the former case, the reason is that virmidi has an open code calling snd_rawmidi_transmit_ack() with the value calculated outside the spinlock. We may use snd_rawmidi_transmit() in a loop just for consuming the input data, but even there, there is a race between snd_rawmidi_transmit_peek() and snd_rawmidi_tranmit_ack(). Similarly in the latter case, it calls snd_rawmidi_transmit_peek() and snd_rawmidi_tranmit_ack() separately without protection, so they are racy as well. The patch tries to address these issues by the following ways: - Introduce the unlocked versions of snd_rawmidi_transmit_peek() and snd_rawmidi_transmit_ack() to be called inside the explicit lock. - Rewrite snd_rawmidi_transmit() to be race-free (the former case). - Make the split calls (the latter case) protected in the rawmidi spin lock. Buglink: http://lkml.kernel.org/r/CACT4Y+YPq1+cYLkadwjWa5XjzF1_Vki1eHnVn-Lm0hzhSpu5PA@mail.gmail.com Buglink: http://lkml.kernel.org/r/CACT4Y+acG4iyphdOZx47Nyq_VHGbpJQK-6xNpiqUjaZYqsXOGw@mail.gmail.com Reported-by: Dmitry Vyukov Tested-by: Dmitry Vyukov Signed-off-by: Takashi Iwai Signed-off-by: Jiri Slaby

xen: Add RING_COPY_REQUEST()

2016-04-11T14:43:45Z

commit 454d5d882c7e412b840e3c99010fe81a9862f6fb upstream. Using RING_GET_REQUEST() on a shared ring is easy to use incorrectly (i.e., by not considering that the other end may alter the data in the shared ring while it is being inspected). Safe usage of a request generally requires taking a local copy. Provide a RING_COPY_REQUEST() macro to use instead of RING_GET_REQUEST() and an open-coded memcpy(). This takes care of ensuring that the copy is done correctly regardless of any possible compiler optimizations. Use a volatile source to prevent the compiler from reordering or omitting the copy. This is part of XSA155. Signed-off-by: David Vrabel Signed-off-by: Konrad Rzeszutek Wilk Signed-off-by: Jiri Slaby

locking: Remove atomicy checks from {READ,WRITE}_ONCE

2016-04-11T14:43:45Z

commit 7bd3e239d6c6d1cad276e8f130b386df4234dcd7 upstream. The fact that volatile allows for atomic load/stores is a special case not a requirement for {READ,WRITE}_ONCE(). Their primary purpose is to force the compiler to emit load/stores _once_. Signed-off-by: Peter Zijlstra (Intel) Acked-by: Christian Borntraeger Acked-by: Will Deacon Acked-by: Linus Torvalds Cc: Davidlohr Bueso Cc: H. Peter Anvin Cc: Paul McKenney Cc: Stephen Rothwell Cc: Thomas Gleixner Signed-off-by: Ingo Molnar Signed-off-by: Jiri Slaby