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r: 312302
b: refs/heads/master
c: 1070505
h: refs/heads/master
v: v3
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Ingo Molnar committed Jul 5, 2012
1 parent d2ae591 commit ed6261f
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2 changes: 1 addition & 1 deletion [refs]
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---
refs/heads/master: 3d8986bc7f309483ee09c7a02888bab09072c19b
refs/heads/master: 1070505d18534076bda8ca13b1bc1ab2e09546da
21 changes: 0 additions & 21 deletions trunk/Documentation/ABI/testing/sysfs-block-rssd
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@@ -1,26 +1,5 @@
What: /sys/block/rssd*/registers
Date: March 2012
KernelVersion: 3.3
Contact: Asai Thambi S P <asamymuthupa@micron.com>
Description: This is a read-only file. Dumps below driver information and
hardware registers.
- S ACTive
- Command Issue
- Completed
- PORT IRQ STAT
- HOST IRQ STAT
- Allocated
- Commands in Q

What: /sys/block/rssd*/status
Date: April 2012
KernelVersion: 3.4
Contact: Asai Thambi S P <asamymuthupa@micron.com>
Description: This is a read-only file. Indicates the status of the device.

What: /sys/block/rssd*/flags
Date: May 2012
KernelVersion: 3.5
Contact: Asai Thambi S P <asamymuthupa@micron.com>
Description: This is a read-only file. Dumps the flags in port and driver
data structure
131 changes: 46 additions & 85 deletions trunk/Documentation/device-mapper/verity.txt
Original file line number Diff line number Diff line change
Expand Up @@ -7,39 +7,39 @@ This target is read-only.

Construction Parameters
=======================
<version> <dev> <hash_dev> <hash_start>
<version> <dev> <hash_dev>
<data_block_size> <hash_block_size>
<num_data_blocks> <hash_start_block>
<algorithm> <digest> <salt>

<version>
This is the version number of the on-disk format.
This is the type of the on-disk hash format.

0 is the original format used in the Chromium OS.
The salt is appended when hashing, digests are stored continuously and
the rest of the block is padded with zeros.
The salt is appended when hashing, digests are stored continuously and
the rest of the block is padded with zeros.

1 is the current format that should be used for new devices.
The salt is prepended when hashing and each digest is
padded with zeros to the power of two.
The salt is prepended when hashing and each digest is
padded with zeros to the power of two.

<dev>
This is the device containing the data the integrity of which needs to be
This is the device containing data, the integrity of which needs to be
checked. It may be specified as a path, like /dev/sdaX, or a device number,
<major>:<minor>.

<hash_dev>
This is the device that that supplies the hash tree data. It may be
This is the device that supplies the hash tree data. It may be
specified similarly to the device path and may be the same device. If the
same device is used, the hash_start should be outside of the dm-verity
configured device size.
same device is used, the hash_start should be outside the configured
dm-verity device.

<data_block_size>
The block size on a data device. Each block corresponds to one digest on
the hash device.
The block size on a data device in bytes.
Each block corresponds to one digest on the hash device.

<hash_block_size>
The size of a hash block.
The size of a hash block in bytes.

<num_data_blocks>
The number of data blocks on the data device. Additional blocks are
Expand All @@ -65,28 +65,28 @@ Construction Parameters
Theory of operation
===================

dm-verity is meant to be setup as part of a verified boot path. This
dm-verity is meant to be set up as part of a verified boot path. This
may be anything ranging from a boot using tboot or trustedgrub to just
booting from a known-good device (like a USB drive or CD).

When a dm-verity device is configured, it is expected that the caller
has been authenticated in some way (cryptographic signatures, etc).
After instantiation, all hashes will be verified on-demand during
disk access. If they cannot be verified up to the root node of the
tree, the root hash, then the I/O will fail. This should identify
tree, the root hash, then the I/O will fail. This should detect
tampering with any data on the device and the hash data.

Cryptographic hashes are used to assert the integrity of the device on a
per-block basis. This allows for a lightweight hash computation on first read
into the page cache. Block hashes are stored linearly-aligned to the nearest
block the size of a page.
per-block basis. This allows for a lightweight hash computation on first read
into the page cache. Block hashes are stored linearly, aligned to the nearest
block size.

Hash Tree
---------

Each node in the tree is a cryptographic hash. If it is a leaf node, the hash
is of some block data on disk. If it is an intermediary node, then the hash is
of a number of child nodes.
of some data block on disk is calculated. If it is an intermediary node,
the hash of a number of child nodes is calculated.

Each entry in the tree is a collection of neighboring nodes that fit in one
block. The number is determined based on block_size and the size of the
Expand All @@ -110,85 +110,46 @@ alg = sha256, num_blocks = 32768, block_size = 4096
On-disk format
==============

Below is the recommended on-disk format. The verity kernel code does not
read the on-disk header. It only reads the hash blocks which directly
follow the header. It is expected that a user-space tool will verify the
integrity of the verity_header and then call dmsetup with the correct
parameters. Alternatively, the header can be omitted and the dmsetup
parameters can be passed via the kernel command-line in a rooted chain
of trust where the command-line is verified.
The verity kernel code does not read the verity metadata on-disk header.
It only reads the hash blocks which directly follow the header.
It is expected that a user-space tool will verify the integrity of the
verity header.

The on-disk format is especially useful in cases where the hash blocks
are on a separate partition. The magic number allows easy identification
of the partition contents. Alternatively, the hash blocks can be stored
in the same partition as the data to be verified. In such a configuration
the filesystem on the partition would be sized a little smaller than
the full-partition, leaving room for the hash blocks.

struct superblock {
uint8_t signature[8]
"verity\0\0";

uint8_t version;
1 - current format

uint8_t data_block_bits;
log2(data block size)

uint8_t hash_block_bits;
log2(hash block size)

uint8_t pad1[1];
zero padding

uint16_t salt_size;
big-endian salt size

uint8_t pad2[2];
zero padding

uint32_t data_blocks_hi;
big-endian high 32 bits of the 64-bit number of data blocks

uint32_t data_blocks_lo;
big-endian low 32 bits of the 64-bit number of data blocks

uint8_t algorithm[16];
cryptographic algorithm

uint8_t salt[384];
salt (the salt size is specified above)

uint8_t pad3[88];
zero padding to 512-byte boundary
}
Alternatively, the header can be omitted and the dmsetup parameters can
be passed via the kernel command-line in a rooted chain of trust where
the command-line is verified.

Directly following the header (and with sector number padded to the next hash
block boundary) are the hash blocks which are stored a depth at a time
(starting from the root), sorted in order of increasing index.

The full specification of kernel parameters and on-disk metadata format
is available at the cryptsetup project's wiki page
http://code.google.com/p/cryptsetup/wiki/DMVerity

Status
======
V (for Valid) is returned if every check performed so far was valid.
If any check failed, C (for Corruption) is returned.

Example
=======

Setup a device:
dmsetup create vroot --table \
"0 2097152 "\
"verity 1 /dev/sda1 /dev/sda2 4096 4096 2097152 1 "\
Set up a device:
# dmsetup create vroot --readonly --table \
"0 2097152 verity 1 /dev/sda1 /dev/sda2 4096 4096 262144 1 sha256 "\
"4392712ba01368efdf14b05c76f9e4df0d53664630b5d48632ed17a137f39076 "\
"1234000000000000000000000000000000000000000000000000000000000000"

A command line tool veritysetup is available to compute or verify
the hash tree or activate the kernel driver. This is available from
the LVM2 upstream repository and may be supplied as a package called
device-mapper-verity-tools:
git://sources.redhat.com/git/lvm2
http://sourceware.org/git/?p=lvm2.git
http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/verity?cvsroot=lvm2

veritysetup -a vroot /dev/sda1 /dev/sda2 \
4392712ba01368efdf14b05c76f9e4df0d53664630b5d48632ed17a137f39076
the hash tree or activate the kernel device. This is available from
the cryptsetup upstream repository http://code.google.com/p/cryptsetup/
(as a libcryptsetup extension).

Create hash on the device:
# veritysetup format /dev/sda1 /dev/sda2
...
Root hash: 4392712ba01368efdf14b05c76f9e4df0d53664630b5d48632ed17a137f39076

Activate the device:
# veritysetup create vroot /dev/sda1 /dev/sda2 \
4392712ba01368efdf14b05c76f9e4df0d53664630b5d48632ed17a137f39076
50 changes: 50 additions & 0 deletions trunk/Documentation/prctl/no_new_privs.txt
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@@ -0,0 +1,50 @@
The execve system call can grant a newly-started program privileges that
its parent did not have. The most obvious examples are setuid/setgid
programs and file capabilities. To prevent the parent program from
gaining these privileges as well, the kernel and user code must be
careful to prevent the parent from doing anything that could subvert the
child. For example:

- The dynamic loader handles LD_* environment variables differently if
a program is setuid.

- chroot is disallowed to unprivileged processes, since it would allow
/etc/passwd to be replaced from the point of view of a process that
inherited chroot.

- The exec code has special handling for ptrace.

These are all ad-hoc fixes. The no_new_privs bit (since Linux 3.5) is a
new, generic mechanism to make it safe for a process to modify its
execution environment in a manner that persists across execve. Any task
can set no_new_privs. Once the bit is set, it is inherited across fork,
clone, and execve and cannot be unset. With no_new_privs set, execve
promises not to grant the privilege to do anything that could not have
been done without the execve call. For example, the setuid and setgid
bits will no longer change the uid or gid; file capabilities will not
add to the permitted set, and LSMs will not relax constraints after
execve.

Note that no_new_privs does not prevent privilege changes that do not
involve execve. An appropriately privileged task can still call
setuid(2) and receive SCM_RIGHTS datagrams.

There are two main use cases for no_new_privs so far:

- Filters installed for the seccomp mode 2 sandbox persist across
execve and can change the behavior of newly-executed programs.
Unprivileged users are therefore only allowed to install such filters
if no_new_privs is set.

- By itself, no_new_privs can be used to reduce the attack surface
available to an unprivileged user. If everything running with a
given uid has no_new_privs set, then that uid will be unable to
escalate its privileges by directly attacking setuid, setgid, and
fcap-using binaries; it will need to compromise something without the
no_new_privs bit set first.

In the future, other potentially dangerous kernel features could become
available to unprivileged tasks if no_new_privs is set. In principle,
several options to unshare(2) and clone(2) would be safe when
no_new_privs is set, and no_new_privs + chroot is considerable less
dangerous than chroot by itself.
4 changes: 2 additions & 2 deletions trunk/MAINTAINERS
Original file line number Diff line number Diff line change
Expand Up @@ -4654,8 +4654,8 @@ L: netfilter@vger.kernel.org
L: coreteam@netfilter.org
W: http://www.netfilter.org/
W: http://www.iptables.org/
T: git git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-2.6.git
T: git git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next-2.6.git
T: git git://1984.lsi.us.es/nf
T: git git://1984.lsi.us.es/nf-next
S: Supported
F: include/linux/netfilter*
F: include/linux/netfilter/
Expand Down
2 changes: 2 additions & 0 deletions trunk/arch/arm/kernel/vmlinux.lds.S
Original file line number Diff line number Diff line change
Expand Up @@ -183,7 +183,9 @@ SECTIONS
}
#endif

#ifdef CONFIG_SMP
PERCPU_SECTION(L1_CACHE_BYTES)
#endif

#ifdef CONFIG_XIP_KERNEL
__data_loc = ALIGN(4); /* location in binary */
Expand Down
74 changes: 74 additions & 0 deletions trunk/arch/arm/mm/mmu.c
Original file line number Diff line number Diff line change
Expand Up @@ -791,6 +791,79 @@ void __init iotable_init(struct map_desc *io_desc, int nr)
}
}

#ifndef CONFIG_ARM_LPAE

/*
* The Linux PMD is made of two consecutive section entries covering 2MB
* (see definition in include/asm/pgtable-2level.h). However a call to
* create_mapping() may optimize static mappings by using individual
* 1MB section mappings. This leaves the actual PMD potentially half
* initialized if the top or bottom section entry isn't used, leaving it
* open to problems if a subsequent ioremap() or vmalloc() tries to use
* the virtual space left free by that unused section entry.
*
* Let's avoid the issue by inserting dummy vm entries covering the unused
* PMD halves once the static mappings are in place.
*/

static void __init pmd_empty_section_gap(unsigned long addr)
{
struct vm_struct *vm;

vm = early_alloc_aligned(sizeof(*vm), __alignof__(*vm));
vm->addr = (void *)addr;
vm->size = SECTION_SIZE;
vm->flags = VM_IOREMAP | VM_ARM_STATIC_MAPPING;
vm->caller = pmd_empty_section_gap;
vm_area_add_early(vm);
}

static void __init fill_pmd_gaps(void)
{
struct vm_struct *vm;
unsigned long addr, next = 0;
pmd_t *pmd;

/* we're still single threaded hence no lock needed here */
for (vm = vmlist; vm; vm = vm->next) {
if (!(vm->flags & VM_ARM_STATIC_MAPPING))
continue;
addr = (unsigned long)vm->addr;
if (addr < next)
continue;

/*
* Check if this vm starts on an odd section boundary.
* If so and the first section entry for this PMD is free
* then we block the corresponding virtual address.
*/
if ((addr & ~PMD_MASK) == SECTION_SIZE) {
pmd = pmd_off_k(addr);
if (pmd_none(*pmd))
pmd_empty_section_gap(addr & PMD_MASK);
}

/*
* Then check if this vm ends on an odd section boundary.
* If so and the second section entry for this PMD is empty
* then we block the corresponding virtual address.
*/
addr += vm->size;
if ((addr & ~PMD_MASK) == SECTION_SIZE) {
pmd = pmd_off_k(addr) + 1;
if (pmd_none(*pmd))
pmd_empty_section_gap(addr);
}

/* no need to look at any vm entry until we hit the next PMD */
next = (addr + PMD_SIZE - 1) & PMD_MASK;
}
}

#else
#define fill_pmd_gaps() do { } while (0)
#endif

static void * __initdata vmalloc_min =
(void *)(VMALLOC_END - (240 << 20) - VMALLOC_OFFSET);

Expand Down Expand Up @@ -1072,6 +1145,7 @@ static void __init devicemaps_init(struct machine_desc *mdesc)
*/
if (mdesc->map_io)
mdesc->map_io();
fill_pmd_gaps();

/*
* Finally flush the caches and tlb to ensure that we're in a
Expand Down
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