Revision 2172fa709ab32ca60e86179dc67d0857be8e2c98 authored by Stephen Smalley on 30 January 2014, 16:26:59 UTC, committed by Paul Moore on 05 February 2014, 17:20:51 UTC
Setting an empty security context (length=0) on a file will lead to incorrectly dereferencing the type and other fields of the security context structure, yielding a kernel BUG. As a zero-length security context is never valid, just reject all such security contexts whether coming from userspace via setxattr or coming from the filesystem upon a getxattr request by SELinux. Setting a security context value (empty or otherwise) unknown to SELinux in the first place is only possible for a root process (CAP_MAC_ADMIN), and, if running SELinux in enforcing mode, only if the corresponding SELinux mac_admin permission is also granted to the domain by policy. In Fedora policies, this is only allowed for specific domains such as livecd for setting down security contexts that are not defined in the build host policy. Reproducer: su setenforce 0 touch foo setfattr -n security.selinux foo Caveat: Relabeling or removing foo after doing the above may not be possible without booting with SELinux disabled. Any subsequent access to foo after doing the above will also trigger the BUG. BUG output from Matthew Thode: [ 473.893141] ------------[ cut here ]------------ [ 473.962110] kernel BUG at security/selinux/ss/services.c:654! [ 473.995314] invalid opcode: 0000 [#6] SMP [ 474.027196] Modules linked in: [ 474.058118] CPU: 0 PID: 8138 Comm: ls Tainted: G D I 3.13.0-grsec #1 [ 474.116637] Hardware name: Supermicro X8ST3/X8ST3, BIOS 2.0 07/29/10 [ 474.149768] task: ffff8805f50cd010 ti: ffff8805f50cd488 task.ti: ffff8805f50cd488 [ 474.183707] RIP: 0010:[<ffffffff814681c7>] [<ffffffff814681c7>] context_struct_compute_av+0xce/0x308 [ 474.219954] RSP: 0018:ffff8805c0ac3c38 EFLAGS: 00010246 [ 474.252253] RAX: 0000000000000000 RBX: ffff8805c0ac3d94 RCX: 0000000000000100 [ 474.287018] RDX: ffff8805e8aac000 RSI: 00000000ffffffff RDI: ffff8805e8aaa000 [ 474.321199] RBP: ffff8805c0ac3cb8 R08: 0000000000000010 R09: 0000000000000006 [ 474.357446] R10: 0000000000000000 R11: ffff8805c567a000 R12: 0000000000000006 [ 474.419191] R13: ffff8805c2b74e88 R14: 00000000000001da R15: 0000000000000000 [ 474.453816] FS: 00007f2e75220800(0000) GS:ffff88061fc00000(0000) knlGS:0000000000000000 [ 474.489254] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 474.522215] CR2: 00007f2e74716090 CR3: 00000005c085e000 CR4: 00000000000207f0 [ 474.556058] Stack: [ 474.584325] ffff8805c0ac3c98 ffffffff811b549b ffff8805c0ac3c98 ffff8805f1190a40 [ 474.618913] ffff8805a6202f08 ffff8805c2b74e88 00068800d0464990 ffff8805e8aac860 [ 474.653955] ffff8805c0ac3cb8 000700068113833a ffff880606c75060 ffff8805c0ac3d94 [ 474.690461] Call Trace: [ 474.723779] [<ffffffff811b549b>] ? lookup_fast+0x1cd/0x22a [ 474.778049] [<ffffffff81468824>] security_compute_av+0xf4/0x20b [ 474.811398] [<ffffffff8196f419>] avc_compute_av+0x2a/0x179 [ 474.843813] [<ffffffff8145727b>] avc_has_perm+0x45/0xf4 [ 474.875694] [<ffffffff81457d0e>] inode_has_perm+0x2a/0x31 [ 474.907370] [<ffffffff81457e76>] selinux_inode_getattr+0x3c/0x3e [ 474.938726] [<ffffffff81455cf6>] security_inode_getattr+0x1b/0x22 [ 474.970036] [<ffffffff811b057d>] vfs_getattr+0x19/0x2d [ 475.000618] [<ffffffff811b05e5>] vfs_fstatat+0x54/0x91 [ 475.030402] [<ffffffff811b063b>] vfs_lstat+0x19/0x1b [ 475.061097] [<ffffffff811b077e>] SyS_newlstat+0x15/0x30 [ 475.094595] [<ffffffff8113c5c1>] ? __audit_syscall_entry+0xa1/0xc3 [ 475.148405] [<ffffffff8197791e>] system_call_fastpath+0x16/0x1b [ 475.179201] Code: 00 48 85 c0 48 89 45 b8 75 02 0f 0b 48 8b 45 a0 48 8b 3d 45 d0 b6 00 8b 40 08 89 c6 ff ce e8 d1 b0 06 00 48 85 c0 49 89 c7 75 02 <0f> 0b 48 8b 45 b8 4c 8b 28 eb 1e 49 8d 7d 08 be 80 01 00 00 e8 [ 475.255884] RIP [<ffffffff814681c7>] context_struct_compute_av+0xce/0x308 [ 475.296120] RSP <ffff8805c0ac3c38> [ 475.328734] ---[ end trace f076482e9d754adc ]--- Reported-by: Matthew Thode <mthode@mthode.org> Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov> Cc: stable@vger.kernel.org Signed-off-by: Paul Moore <pmoore@redhat.com>
1 parent 6a96e15
pata_sc1200.c
/*
* New ATA layer SC1200 driver Alan Cox <alan@lxorguk.ukuu.org.uk>
*
* TODO: Mode selection filtering
* TODO: Needs custom DMA cleanup code
*
* Based very heavily on
*
* linux/drivers/ide/pci/sc1200.c Version 0.91 28-Jan-2003
*
* Copyright (C) 2000-2002 Mark Lord <mlord@pobox.com>
* May be copied or modified under the terms of the GNU General Public License
*
* Development of this chipset driver was funded
* by the nice folks at National Semiconductor.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/delay.h>
#include <scsi/scsi_host.h>
#include <linux/libata.h>
#define DRV_NAME "pata_sc1200"
#define DRV_VERSION "0.2.6"
#define SC1200_REV_A 0x00
#define SC1200_REV_B1 0x01
#define SC1200_REV_B3 0x02
#define SC1200_REV_C1 0x03
#define SC1200_REV_D1 0x04
/**
* sc1200_clock - PCI clock
*
* Return the PCI bus clocking for the SC1200 chipset configuration
* in use. We return 0 for 33MHz 1 for 48MHz and 2 for 66Mhz
*/
static int sc1200_clock(void)
{
/* Magic registers that give us the chipset data */
u8 chip_id = inb(0x903C);
u8 silicon_rev = inb(0x903D);
u16 pci_clock;
if (chip_id == 0x04 && silicon_rev < SC1200_REV_B1)
return 0; /* 33 MHz mode */
/* Clock generator configuration 0x901E its 8/9 are the PCI clocking
0/3 is 33Mhz 1 is 48 2 is 66 */
pci_clock = inw(0x901E);
pci_clock >>= 8;
pci_clock &= 0x03;
if (pci_clock == 3)
pci_clock = 0;
return pci_clock;
}
/**
* sc1200_set_piomode - PIO setup
* @ap: ATA interface
* @adev: device on the interface
*
* Set our PIO requirements. This is fairly simple on the SC1200
*/
static void sc1200_set_piomode(struct ata_port *ap, struct ata_device *adev)
{
static const u32 pio_timings[4][5] = {
/* format0, 33Mhz */
{ 0x00009172, 0x00012171, 0x00020080, 0x00032010, 0x00040010 },
/* format1, 33Mhz */
{ 0xd1329172, 0x71212171, 0x30200080, 0x20102010, 0x00100010 },
/* format1, 48Mhz */
{ 0xfaa3f4f3, 0xc23232b2, 0x513101c1, 0x31213121, 0x10211021 },
/* format1, 66Mhz */
{ 0xfff4fff4, 0xf35353d3, 0x814102f1, 0x42314231, 0x11311131 }
};
struct pci_dev *pdev = to_pci_dev(ap->host->dev);
u32 format;
unsigned int reg = 0x40 + 0x10 * ap->port_no;
int mode = adev->pio_mode - XFER_PIO_0;
pci_read_config_dword(pdev, reg + 4, &format);
format >>= 31;
format += sc1200_clock();
pci_write_config_dword(pdev, reg + 8 * adev->devno,
pio_timings[format][mode]);
}
/**
* sc1200_set_dmamode - DMA timing setup
* @ap: ATA interface
* @adev: Device being configured
*
* We cannot mix MWDMA and UDMA without reloading timings each switch
* master to slave.
*/
static void sc1200_set_dmamode(struct ata_port *ap, struct ata_device *adev)
{
static const u32 udma_timing[3][3] = {
{ 0x00921250, 0x00911140, 0x00911030 },
{ 0x00932470, 0x00922260, 0x00922140 },
{ 0x009436A1, 0x00933481, 0x00923261 }
};
static const u32 mwdma_timing[3][3] = {
{ 0x00077771, 0x00012121, 0x00002020 },
{ 0x000BBBB2, 0x00024241, 0x00013131 },
{ 0x000FFFF3, 0x00035352, 0x00015151 }
};
int clock = sc1200_clock();
struct pci_dev *pdev = to_pci_dev(ap->host->dev);
unsigned int reg = 0x40 + 0x10 * ap->port_no;
int mode = adev->dma_mode;
u32 format;
if (mode >= XFER_UDMA_0)
format = udma_timing[clock][mode - XFER_UDMA_0];
else
format = mwdma_timing[clock][mode - XFER_MW_DMA_0];
if (adev->devno == 0) {
u32 timings;
pci_read_config_dword(pdev, reg + 4, &timings);
timings &= 0x80000000UL;
timings |= format;
pci_write_config_dword(pdev, reg + 4, timings);
} else
pci_write_config_dword(pdev, reg + 12, format);
}
/**
* sc1200_qc_issue - command issue
* @qc: command pending
*
* Called when the libata layer is about to issue a command. We wrap
* this interface so that we can load the correct ATA timings if
* necessary. Specifically we have a problem that there is only
* one MWDMA/UDMA bit.
*/
static unsigned int sc1200_qc_issue(struct ata_queued_cmd *qc)
{
struct ata_port *ap = qc->ap;
struct ata_device *adev = qc->dev;
struct ata_device *prev = ap->private_data;
/* See if the DMA settings could be wrong */
if (ata_dma_enabled(adev) && adev != prev && prev != NULL) {
/* Maybe, but do the channels match MWDMA/UDMA ? */
if ((ata_using_udma(adev) && !ata_using_udma(prev)) ||
(ata_using_udma(prev) && !ata_using_udma(adev)))
/* Switch the mode bits */
sc1200_set_dmamode(ap, adev);
}
return ata_bmdma_qc_issue(qc);
}
/**
* sc1200_qc_defer - implement serialization
* @qc: command
*
* Serialize command issue on this controller.
*/
static int sc1200_qc_defer(struct ata_queued_cmd *qc)
{
struct ata_host *host = qc->ap->host;
struct ata_port *alt = host->ports[1 ^ qc->ap->port_no];
int rc;
/* First apply the usual rules */
rc = ata_std_qc_defer(qc);
if (rc != 0)
return rc;
/* Now apply serialization rules. Only allow a command if the
other channel state machine is idle */
if (alt && alt->qc_active)
return ATA_DEFER_PORT;
return 0;
}
static struct scsi_host_template sc1200_sht = {
ATA_BMDMA_SHT(DRV_NAME),
.sg_tablesize = LIBATA_DUMB_MAX_PRD,
};
static struct ata_port_operations sc1200_port_ops = {
.inherits = &ata_bmdma_port_ops,
.qc_prep = ata_bmdma_dumb_qc_prep,
.qc_issue = sc1200_qc_issue,
.qc_defer = sc1200_qc_defer,
.cable_detect = ata_cable_40wire,
.set_piomode = sc1200_set_piomode,
.set_dmamode = sc1200_set_dmamode,
};
/**
* sc1200_init_one - Initialise an SC1200
* @dev: PCI device
* @id: Entry in match table
*
* Just throw the needed data at the libata helper and it does all
* our work.
*/
static int sc1200_init_one(struct pci_dev *dev, const struct pci_device_id *id)
{
static const struct ata_port_info info = {
.flags = ATA_FLAG_SLAVE_POSS,
.pio_mask = ATA_PIO4,
.mwdma_mask = ATA_MWDMA2,
.udma_mask = ATA_UDMA2,
.port_ops = &sc1200_port_ops
};
const struct ata_port_info *ppi[] = { &info, NULL };
return ata_pci_bmdma_init_one(dev, ppi, &sc1200_sht, NULL, 0);
}
static const struct pci_device_id sc1200[] = {
{ PCI_VDEVICE(NS, PCI_DEVICE_ID_NS_SCx200_IDE), },
{ },
};
static struct pci_driver sc1200_pci_driver = {
.name = DRV_NAME,
.id_table = sc1200,
.probe = sc1200_init_one,
.remove = ata_pci_remove_one,
#ifdef CONFIG_PM
.suspend = ata_pci_device_suspend,
.resume = ata_pci_device_resume,
#endif
};
module_pci_driver(sc1200_pci_driver);
MODULE_AUTHOR("Alan Cox, Mark Lord");
MODULE_DESCRIPTION("low-level driver for the NS/AMD SC1200");
MODULE_LICENSE("GPL");
MODULE_DEVICE_TABLE(pci, sc1200);
MODULE_VERSION(DRV_VERSION);
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