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_cypress.c
/*
* pata_cypress.c - Cypress PATA for new ATA layer
* (C) 2006 Red Hat Inc
* Alan Cox
*
* Based heavily on
* linux/drivers/ide/pci/cy82c693.c Version 0.40 Sep. 10, 2002
*
*/
#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_cypress"
#define DRV_VERSION "0.1.5"
/* here are the offset definitions for the registers */
enum {
CY82_IDE_CMDREG = 0x04,
CY82_IDE_ADDRSETUP = 0x48,
CY82_IDE_MASTER_IOR = 0x4C,
CY82_IDE_MASTER_IOW = 0x4D,
CY82_IDE_SLAVE_IOR = 0x4E,
CY82_IDE_SLAVE_IOW = 0x4F,
CY82_IDE_MASTER_8BIT = 0x50,
CY82_IDE_SLAVE_8BIT = 0x51,
CY82_INDEX_PORT = 0x22,
CY82_DATA_PORT = 0x23,
CY82_INDEX_CTRLREG1 = 0x01,
CY82_INDEX_CHANNEL0 = 0x30,
CY82_INDEX_CHANNEL1 = 0x31,
CY82_INDEX_TIMEOUT = 0x32
};
/**
* cy82c693_set_piomode - set initial PIO mode data
* @ap: ATA interface
* @adev: ATA device
*
* Called to do the PIO mode setup.
*/
static void cy82c693_set_piomode(struct ata_port *ap, struct ata_device *adev)
{
struct pci_dev *pdev = to_pci_dev(ap->host->dev);
struct ata_timing t;
const unsigned long T = 1000000 / 33;
short time_16, time_8;
u32 addr;
if (ata_timing_compute(adev, adev->pio_mode, &t, T, 1) < 0) {
printk(KERN_ERR DRV_NAME ": mome computation failed.\n");
return;
}
time_16 = clamp_val(t.recover - 1, 0, 15) |
(clamp_val(t.active - 1, 0, 15) << 4);
time_8 = clamp_val(t.act8b - 1, 0, 15) |
(clamp_val(t.rec8b - 1, 0, 15) << 4);
if (adev->devno == 0) {
pci_read_config_dword(pdev, CY82_IDE_ADDRSETUP, &addr);
addr &= ~0x0F; /* Mask bits */
addr |= clamp_val(t.setup - 1, 0, 15);
pci_write_config_dword(pdev, CY82_IDE_ADDRSETUP, addr);
pci_write_config_byte(pdev, CY82_IDE_MASTER_IOR, time_16);
pci_write_config_byte(pdev, CY82_IDE_MASTER_IOW, time_16);
pci_write_config_byte(pdev, CY82_IDE_MASTER_8BIT, time_8);
} else {
pci_read_config_dword(pdev, CY82_IDE_ADDRSETUP, &addr);
addr &= ~0xF0; /* Mask bits */
addr |= (clamp_val(t.setup - 1, 0, 15) << 4);
pci_write_config_dword(pdev, CY82_IDE_ADDRSETUP, addr);
pci_write_config_byte(pdev, CY82_IDE_SLAVE_IOR, time_16);
pci_write_config_byte(pdev, CY82_IDE_SLAVE_IOW, time_16);
pci_write_config_byte(pdev, CY82_IDE_SLAVE_8BIT, time_8);
}
}
/**
* cy82c693_set_dmamode - set initial DMA mode data
* @ap: ATA interface
* @adev: ATA device
*
* Called to do the DMA mode setup.
*/
static void cy82c693_set_dmamode(struct ata_port *ap, struct ata_device *adev)
{
int reg = CY82_INDEX_CHANNEL0 + ap->port_no;
/* Be afraid, be very afraid. Magic registers in low I/O space */
outb(reg, 0x22);
outb(adev->dma_mode - XFER_MW_DMA_0, 0x23);
/* 0x50 gives the best behaviour on the Alpha's using this chip */
outb(CY82_INDEX_TIMEOUT, 0x22);
outb(0x50, 0x23);
}
static struct scsi_host_template cy82c693_sht = {
ATA_BMDMA_SHT(DRV_NAME),
};
static struct ata_port_operations cy82c693_port_ops = {
.inherits = &ata_bmdma_port_ops,
.cable_detect = ata_cable_40wire,
.set_piomode = cy82c693_set_piomode,
.set_dmamode = cy82c693_set_dmamode,
};
static int cy82c693_init_one(struct pci_dev *pdev, 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,
.port_ops = &cy82c693_port_ops
};
const struct ata_port_info *ppi[] = { &info, &ata_dummy_port_info };
/* Devfn 1 is the ATA primary. The secondary is magic and on devfn2.
For the moment we don't handle the secondary. FIXME */
if (PCI_FUNC(pdev->devfn) != 1)
return -ENODEV;
return ata_pci_bmdma_init_one(pdev, ppi, &cy82c693_sht, NULL, 0);
}
static const struct pci_device_id cy82c693[] = {
{ PCI_VDEVICE(CONTAQ, PCI_DEVICE_ID_CONTAQ_82C693), },
{ },
};
static struct pci_driver cy82c693_pci_driver = {
.name = DRV_NAME,
.id_table = cy82c693,
.probe = cy82c693_init_one,
.remove = ata_pci_remove_one,
#ifdef CONFIG_PM
.suspend = ata_pci_device_suspend,
.resume = ata_pci_device_resume,
#endif
};
module_pci_driver(cy82c693_pci_driver);
MODULE_AUTHOR("Alan Cox");
MODULE_DESCRIPTION("low-level driver for the CY82C693 PATA controller");
MODULE_LICENSE("GPL");
MODULE_DEVICE_TABLE(pci, cy82c693);
MODULE_VERSION(DRV_VERSION);
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