https://github.com/torvalds/linux
Revision 462e635e5b73ba9a4c03913b77138cd57ce4b050 authored by Tavis Ormandy on 09 December 2010, 14:29:42 UTC, committed by Linus Torvalds on 15 December 2010, 20:30:36 UTC
The install_special_mapping routine (used, for example, to setup the
vdso) skips the security check before insert_vm_struct, allowing a local
attacker to bypass the mmap_min_addr security restriction by limiting
the available pages for special mappings.
bprm_mm_init() also skips the check, and although I don't think this can
be used to bypass any restrictions, I don't see any reason not to have
the security check.
$ uname -m
x86_64
$ cat /proc/sys/vm/mmap_min_addr
65536
$ cat install_special_mapping.s
section .bss
resb BSS_SIZE
section .text
global _start
_start:
mov eax, __NR_pause
int 0x80
$ nasm -D__NR_pause=29 -DBSS_SIZE=0xfffed000 -f elf -o install_special_mapping.o install_special_mapping.s
$ ld -m elf_i386 -Ttext=0x10000 -Tbss=0x11000 -o install_special_mapping install_special_mapping.o
$ ./install_special_mapping &
[1] 14303
$ cat /proc/14303/maps
0000f000-00010000 r-xp 00000000 00:00 0 [vdso]
00010000-00011000 r-xp 00001000 00:19 2453665 /home/taviso/install_special_mapping
00011000-ffffe000 rwxp 00000000 00:00 0 [stack]
It's worth noting that Red Hat are shipping with mmap_min_addr set to
4096.
Signed-off-by: Tavis Ormandy <taviso@google.com>
Acked-by: Kees Cook <kees@ubuntu.com>
Acked-by: Robert Swiecki <swiecki@google.com>
[ Changed to not drop the error code - akpm ]
Reviewed-by: James Morris <jmorris@namei.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 0fcdcfb
Tip revision: 462e635e5b73ba9a4c03913b77138cd57ce4b050 authored by Tavis Ormandy on 09 December 2010, 14:29:42 UTC
install_special_mapping skips security_file_mmap check.
install_special_mapping skips security_file_mmap check.
Tip revision: 462e635
driver.txt
PCMCIA Driver
-------------
sysfs
-----
New PCMCIA IDs may be added to a device driver pcmcia_device_id table at
runtime as shown below:
echo "match_flags manf_id card_id func_id function device_no \
prod_id_hash[0] prod_id_hash[1] prod_id_hash[2] prod_id_hash[3]" > \
/sys/bus/pcmcia/drivers/{driver}/new_id
All fields are passed in as hexadecimal values (no leading 0x).
The meaning is described in the PCMCIA specification, the match_flags is
a bitwise or-ed combination from PCMCIA_DEV_ID_MATCH_* constants
defined in include/linux/mod_devicetable.h.
Once added, the driver probe routine will be invoked for any unclaimed
PCMCIA device listed in its (newly updated) pcmcia_device_id list.
A common use-case is to add a new device according to the manufacturer ID
and the card ID (form the manf_id and card_id file in the device tree).
For this, just use:
echo "0x3 manf_id card_id 0 0 0 0 0 0 0" > \
/sys/bus/pcmcia/drivers/{driver}/new_id
after loading the driver.
Computing file changes ...
