License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 17:07:57 +03:00
// SPDX-License-Identifier: GPL-2.0
2012-06-01 03:26:44 +04:00
# include <linux/kernel.h>
# include <linux/syscalls.h>
# include <linux/fdtable.h>
# include <linux/string.h>
# include <linux/random.h>
# include <linux/module.h>
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# include <linux/ptrace.h>
2012-06-01 03:26:44 +04:00
# include <linux/init.h>
# include <linux/errno.h>
# include <linux/cache.h>
# include <linux/bug.h>
# include <linux/err.h>
# include <linux/kcmp.h>
2017-07-13 00:34:28 +03:00
# include <linux/capability.h>
# include <linux/list.h>
# include <linux/eventpoll.h>
# include <linux/file.h>
2012-06-01 03:26:44 +04:00
# include <asm/unistd.h>
/*
* We don ' t expose the real in - memory order of objects for security reasons .
* But still the comparison results should be suitable for sorting . So we
* obfuscate kernel pointers values and compare the production instead .
*
* The obfuscation is done in two steps . First we xor the kernel pointer with
* a random value , which puts pointer into a new position in a reordered space .
* Secondly we multiply the xor production with a large odd random number to
* permute its bits even more ( the odd multiplier guarantees that the product
* is unique ever after the high bits are truncated , since any odd number is
* relative prime to 2 ^ n ) .
*
* Note also that the obfuscation itself is invisible to userspace and if needed
* it can be changed to an alternate scheme .
*/
static unsigned long cookies [ KCMP_TYPES ] [ 2 ] __read_mostly ;
static long kptr_obfuscate ( long v , int type )
{
return ( v ^ cookies [ type ] [ 0 ] ) * cookies [ type ] [ 1 ] ;
}
/*
* 0 - equal , i . e . v1 = v2
* 1 - less than , i . e . v1 < v2
* 2 - greater than , i . e . v1 > v2
* 3 - not equal but ordering unavailable ( reserved for future )
*/
static int kcmp_ptr ( void * v1 , void * v2 , enum kcmp_type type )
{
kcmp: fix standard comparison bug
The C operator <= defines a perfectly fine total ordering on the set of
values representable in a long. However, unlike its namesake in the
integers, it is not translation invariant, meaning that we do not have
"b <= c" iff "a+b <= a+c" for all a,b,c.
This means that it is always wrong to try to boil down the relationship
between two longs to a question about the sign of their difference,
because the resulting relation [a LEQ b iff a-b <= 0] is neither
anti-symmetric or transitive. The former is due to -LONG_MIN==LONG_MIN
(take any two a,b with a-b = LONG_MIN; then a LEQ b and b LEQ a, but a !=
b). The latter can either be seen observing that x LEQ x+1 for all x,
implying x LEQ x+1 LEQ x+2 ... LEQ x-1 LEQ x; or more directly with the
simple example a=LONG_MIN, b=0, c=1, for which a-b < 0, b-c < 0, but a-c >
0.
Note that it makes absolutely no difference that a transmogrying bijection
has been applied before the comparison is done. In fact, had the
obfuscation not been done, one could probably not observe the bug
(assuming all values being compared always lie in one half of the address
space, the mathematical value of a-b is always representable in a long).
As it stands, one can easily obtain three file descriptors exhibiting the
non-transitivity of kcmp().
Side note 1: I can't see that ensuring the MSB of the multiplier is
set serves any purpose other than obfuscating the obfuscating code.
Side note 2:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <assert.h>
#include <sys/syscall.h>
enum kcmp_type {
KCMP_FILE,
KCMP_VM,
KCMP_FILES,
KCMP_FS,
KCMP_SIGHAND,
KCMP_IO,
KCMP_SYSVSEM,
KCMP_TYPES,
};
pid_t pid;
int kcmp(pid_t pid1, pid_t pid2, int type,
unsigned long idx1, unsigned long idx2)
{
return syscall(SYS_kcmp, pid1, pid2, type, idx1, idx2);
}
int cmp_fd(int fd1, int fd2)
{
int c = kcmp(pid, pid, KCMP_FILE, fd1, fd2);
if (c < 0) {
perror("kcmp");
exit(1);
}
assert(0 <= c && c < 3);
return c;
}
int cmp_fdp(const void *a, const void *b)
{
static const int normalize[] = {0, -1, 1};
return normalize[cmp_fd(*(int*)a, *(int*)b)];
}
#define MAX 100 /* This is plenty; I've seen it trigger for MAX==3 */
int main(int argc, char *argv[])
{
int r, s, count = 0;
int REL[3] = {0,0,0};
int fd[MAX];
pid = getpid();
while (count < MAX) {
r = open("/dev/null", O_RDONLY);
if (r < 0)
break;
fd[count++] = r;
}
printf("opened %d file descriptors\n", count);
for (r = 0; r < count; ++r) {
for (s = r+1; s < count; ++s) {
REL[cmp_fd(fd[r], fd[s])]++;
}
}
printf("== %d\t< %d\t> %d\n", REL[0], REL[1], REL[2]);
qsort(fd, count, sizeof(fd[0]), cmp_fdp);
memset(REL, 0, sizeof(REL));
for (r = 0; r < count; ++r) {
for (s = r+1; s < count; ++s) {
REL[cmp_fd(fd[r], fd[s])]++;
}
}
printf("== %d\t< %d\t> %d\n", REL[0], REL[1], REL[2]);
return (REL[0] + REL[2] != 0);
}
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
"Eric W. Biederman" <ebiederm@xmission.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-09-10 01:51:01 +04:00
long t1 , t2 ;
2012-06-01 03:26:44 +04:00
kcmp: fix standard comparison bug
The C operator <= defines a perfectly fine total ordering on the set of
values representable in a long. However, unlike its namesake in the
integers, it is not translation invariant, meaning that we do not have
"b <= c" iff "a+b <= a+c" for all a,b,c.
This means that it is always wrong to try to boil down the relationship
between two longs to a question about the sign of their difference,
because the resulting relation [a LEQ b iff a-b <= 0] is neither
anti-symmetric or transitive. The former is due to -LONG_MIN==LONG_MIN
(take any two a,b with a-b = LONG_MIN; then a LEQ b and b LEQ a, but a !=
b). The latter can either be seen observing that x LEQ x+1 for all x,
implying x LEQ x+1 LEQ x+2 ... LEQ x-1 LEQ x; or more directly with the
simple example a=LONG_MIN, b=0, c=1, for which a-b < 0, b-c < 0, but a-c >
0.
Note that it makes absolutely no difference that a transmogrying bijection
has been applied before the comparison is done. In fact, had the
obfuscation not been done, one could probably not observe the bug
(assuming all values being compared always lie in one half of the address
space, the mathematical value of a-b is always representable in a long).
As it stands, one can easily obtain three file descriptors exhibiting the
non-transitivity of kcmp().
Side note 1: I can't see that ensuring the MSB of the multiplier is
set serves any purpose other than obfuscating the obfuscating code.
Side note 2:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <assert.h>
#include <sys/syscall.h>
enum kcmp_type {
KCMP_FILE,
KCMP_VM,
KCMP_FILES,
KCMP_FS,
KCMP_SIGHAND,
KCMP_IO,
KCMP_SYSVSEM,
KCMP_TYPES,
};
pid_t pid;
int kcmp(pid_t pid1, pid_t pid2, int type,
unsigned long idx1, unsigned long idx2)
{
return syscall(SYS_kcmp, pid1, pid2, type, idx1, idx2);
}
int cmp_fd(int fd1, int fd2)
{
int c = kcmp(pid, pid, KCMP_FILE, fd1, fd2);
if (c < 0) {
perror("kcmp");
exit(1);
}
assert(0 <= c && c < 3);
return c;
}
int cmp_fdp(const void *a, const void *b)
{
static const int normalize[] = {0, -1, 1};
return normalize[cmp_fd(*(int*)a, *(int*)b)];
}
#define MAX 100 /* This is plenty; I've seen it trigger for MAX==3 */
int main(int argc, char *argv[])
{
int r, s, count = 0;
int REL[3] = {0,0,0};
int fd[MAX];
pid = getpid();
while (count < MAX) {
r = open("/dev/null", O_RDONLY);
if (r < 0)
break;
fd[count++] = r;
}
printf("opened %d file descriptors\n", count);
for (r = 0; r < count; ++r) {
for (s = r+1; s < count; ++s) {
REL[cmp_fd(fd[r], fd[s])]++;
}
}
printf("== %d\t< %d\t> %d\n", REL[0], REL[1], REL[2]);
qsort(fd, count, sizeof(fd[0]), cmp_fdp);
memset(REL, 0, sizeof(REL));
for (r = 0; r < count; ++r) {
for (s = r+1; s < count; ++s) {
REL[cmp_fd(fd[r], fd[s])]++;
}
}
printf("== %d\t< %d\t> %d\n", REL[0], REL[1], REL[2]);
return (REL[0] + REL[2] != 0);
}
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
"Eric W. Biederman" <ebiederm@xmission.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-09-10 01:51:01 +04:00
t1 = kptr_obfuscate ( ( long ) v1 , type ) ;
t2 = kptr_obfuscate ( ( long ) v2 , type ) ;
2012-06-01 03:26:44 +04:00
kcmp: fix standard comparison bug
The C operator <= defines a perfectly fine total ordering on the set of
values representable in a long. However, unlike its namesake in the
integers, it is not translation invariant, meaning that we do not have
"b <= c" iff "a+b <= a+c" for all a,b,c.
This means that it is always wrong to try to boil down the relationship
between two longs to a question about the sign of their difference,
because the resulting relation [a LEQ b iff a-b <= 0] is neither
anti-symmetric or transitive. The former is due to -LONG_MIN==LONG_MIN
(take any two a,b with a-b = LONG_MIN; then a LEQ b and b LEQ a, but a !=
b). The latter can either be seen observing that x LEQ x+1 for all x,
implying x LEQ x+1 LEQ x+2 ... LEQ x-1 LEQ x; or more directly with the
simple example a=LONG_MIN, b=0, c=1, for which a-b < 0, b-c < 0, but a-c >
0.
Note that it makes absolutely no difference that a transmogrying bijection
has been applied before the comparison is done. In fact, had the
obfuscation not been done, one could probably not observe the bug
(assuming all values being compared always lie in one half of the address
space, the mathematical value of a-b is always representable in a long).
As it stands, one can easily obtain three file descriptors exhibiting the
non-transitivity of kcmp().
Side note 1: I can't see that ensuring the MSB of the multiplier is
set serves any purpose other than obfuscating the obfuscating code.
Side note 2:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <assert.h>
#include <sys/syscall.h>
enum kcmp_type {
KCMP_FILE,
KCMP_VM,
KCMP_FILES,
KCMP_FS,
KCMP_SIGHAND,
KCMP_IO,
KCMP_SYSVSEM,
KCMP_TYPES,
};
pid_t pid;
int kcmp(pid_t pid1, pid_t pid2, int type,
unsigned long idx1, unsigned long idx2)
{
return syscall(SYS_kcmp, pid1, pid2, type, idx1, idx2);
}
int cmp_fd(int fd1, int fd2)
{
int c = kcmp(pid, pid, KCMP_FILE, fd1, fd2);
if (c < 0) {
perror("kcmp");
exit(1);
}
assert(0 <= c && c < 3);
return c;
}
int cmp_fdp(const void *a, const void *b)
{
static const int normalize[] = {0, -1, 1};
return normalize[cmp_fd(*(int*)a, *(int*)b)];
}
#define MAX 100 /* This is plenty; I've seen it trigger for MAX==3 */
int main(int argc, char *argv[])
{
int r, s, count = 0;
int REL[3] = {0,0,0};
int fd[MAX];
pid = getpid();
while (count < MAX) {
r = open("/dev/null", O_RDONLY);
if (r < 0)
break;
fd[count++] = r;
}
printf("opened %d file descriptors\n", count);
for (r = 0; r < count; ++r) {
for (s = r+1; s < count; ++s) {
REL[cmp_fd(fd[r], fd[s])]++;
}
}
printf("== %d\t< %d\t> %d\n", REL[0], REL[1], REL[2]);
qsort(fd, count, sizeof(fd[0]), cmp_fdp);
memset(REL, 0, sizeof(REL));
for (r = 0; r < count; ++r) {
for (s = r+1; s < count; ++s) {
REL[cmp_fd(fd[r], fd[s])]++;
}
}
printf("== %d\t< %d\t> %d\n", REL[0], REL[1], REL[2]);
return (REL[0] + REL[2] != 0);
}
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
"Eric W. Biederman" <ebiederm@xmission.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-09-10 01:51:01 +04:00
return ( t1 < t2 ) | ( ( t1 > t2 ) < < 1 ) ;
2012-06-01 03:26:44 +04:00
}
/* The caller must have pinned the task */
static struct file *
get_file_raw_ptr ( struct task_struct * task , unsigned int idx )
{
2020-11-21 02:14:30 +03:00
struct file * file ;
2012-06-01 03:26:44 +04:00
rcu_read_lock ( ) ;
2020-11-21 02:14:30 +03:00
file = task_lookup_fd_rcu ( task , idx ) ;
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rcu_read_unlock ( ) ;
return file ;
}
2020-12-03 23:12:00 +03:00
static void kcmp_unlock ( struct rw_semaphore * l1 , struct rw_semaphore * l2 )
2012-06-01 03:26:44 +04:00
{
2020-12-03 23:12:00 +03:00
if ( likely ( l2 ! = l1 ) )
up_read ( l2 ) ;
up_read ( l1 ) ;
2012-06-01 03:26:44 +04:00
}
2020-12-03 23:12:00 +03:00
static int kcmp_lock ( struct rw_semaphore * l1 , struct rw_semaphore * l2 )
2012-06-01 03:26:44 +04:00
{
int err ;
2020-12-03 23:12:00 +03:00
if ( l2 > l1 )
swap ( l1 , l2 ) ;
2012-06-01 03:26:44 +04:00
2020-12-03 23:12:00 +03:00
err = down_read_killable ( l1 ) ;
if ( ! err & & likely ( l1 ! = l2 ) ) {
err = down_read_killable_nested ( l2 , SINGLE_DEPTH_NESTING ) ;
2012-06-01 03:26:44 +04:00
if ( err )
2020-12-03 23:12:00 +03:00
up_read ( l1 ) ;
2012-06-01 03:26:44 +04:00
}
return err ;
}
2017-07-13 00:34:28 +03:00
# ifdef CONFIG_EPOLL
static int kcmp_epoll_target ( struct task_struct * task1 ,
struct task_struct * task2 ,
unsigned long idx1 ,
struct kcmp_epoll_slot __user * uslot )
{
struct file * filp , * filp_epoll , * filp_tgt ;
struct kcmp_epoll_slot slot ;
if ( copy_from_user ( & slot , uslot , sizeof ( slot ) ) )
return - EFAULT ;
filp = get_file_raw_ptr ( task1 , idx1 ) ;
if ( ! filp )
return - EBADF ;
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filp_epoll = fget_task ( task2 , slot . efd ) ;
if ( ! filp_epoll )
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return - EBADF ;
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filp_tgt = get_epoll_tfile_raw_ptr ( filp_epoll , slot . tfd , slot . toff ) ;
fput ( filp_epoll ) ;
2017-07-13 00:34:28 +03:00
if ( IS_ERR ( filp_tgt ) )
return PTR_ERR ( filp_tgt ) ;
return kcmp_ptr ( filp , filp_tgt , KCMP_FILE ) ;
}
# else
static int kcmp_epoll_target ( struct task_struct * task1 ,
struct task_struct * task2 ,
unsigned long idx1 ,
struct kcmp_epoll_slot __user * uslot )
{
return - EOPNOTSUPP ;
}
# endif
2012-06-01 03:26:44 +04:00
SYSCALL_DEFINE5 ( kcmp , pid_t , pid1 , pid_t , pid2 , int , type ,
unsigned long , idx1 , unsigned long , idx2 )
{
struct task_struct * task1 , * task2 ;
int ret ;
rcu_read_lock ( ) ;
/*
* Tasks are looked up in caller ' s PID namespace only .
*/
task1 = find_task_by_vpid ( pid1 ) ;
task2 = find_task_by_vpid ( pid2 ) ;
if ( ! task1 | | ! task2 )
goto err_no_task ;
get_task_struct ( task1 ) ;
get_task_struct ( task2 ) ;
rcu_read_unlock ( ) ;
/*
* One should have enough rights to inspect task details .
*/
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ret = kcmp_lock ( & task1 - > signal - > exec_update_lock ,
& task2 - > signal - > exec_update_lock ) ;
2012-06-01 03:26:44 +04:00
if ( ret )
goto err ;
ptrace: use fsuid, fsgid, effective creds for fs access checks
By checking the effective credentials instead of the real UID / permitted
capabilities, ensure that the calling process actually intended to use its
credentials.
To ensure that all ptrace checks use the correct caller credentials (e.g.
in case out-of-tree code or newly added code omits the PTRACE_MODE_*CREDS
flag), use two new flags and require one of them to be set.
The problem was that when a privileged task had temporarily dropped its
privileges, e.g. by calling setreuid(0, user_uid), with the intent to
perform following syscalls with the credentials of a user, it still passed
ptrace access checks that the user would not be able to pass.
While an attacker should not be able to convince the privileged task to
perform a ptrace() syscall, this is a problem because the ptrace access
check is reused for things in procfs.
In particular, the following somewhat interesting procfs entries only rely
on ptrace access checks:
/proc/$pid/stat - uses the check for determining whether pointers
should be visible, useful for bypassing ASLR
/proc/$pid/maps - also useful for bypassing ASLR
/proc/$pid/cwd - useful for gaining access to restricted
directories that contain files with lax permissions, e.g. in
this scenario:
lrwxrwxrwx root root /proc/13020/cwd -> /root/foobar
drwx------ root root /root
drwxr-xr-x root root /root/foobar
-rw-r--r-- root root /root/foobar/secret
Therefore, on a system where a root-owned mode 6755 binary changes its
effective credentials as described and then dumps a user-specified file,
this could be used by an attacker to reveal the memory layout of root's
processes or reveal the contents of files he is not allowed to access
(through /proc/$pid/cwd).
[akpm@linux-foundation.org: fix warning]
Signed-off-by: Jann Horn <jann@thejh.net>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: "Serge E. Hallyn" <serge.hallyn@ubuntu.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-21 02:00:04 +03:00
if ( ! ptrace_may_access ( task1 , PTRACE_MODE_READ_REALCREDS ) | |
! ptrace_may_access ( task2 , PTRACE_MODE_READ_REALCREDS ) ) {
2012-06-01 03:26:44 +04:00
ret = - EPERM ;
goto err_unlock ;
}
switch ( type ) {
case KCMP_FILE : {
struct file * filp1 , * filp2 ;
filp1 = get_file_raw_ptr ( task1 , idx1 ) ;
filp2 = get_file_raw_ptr ( task2 , idx2 ) ;
if ( filp1 & & filp2 )
ret = kcmp_ptr ( filp1 , filp2 , KCMP_FILE ) ;
else
ret = - EBADF ;
break ;
}
case KCMP_VM :
ret = kcmp_ptr ( task1 - > mm , task2 - > mm , KCMP_VM ) ;
break ;
case KCMP_FILES :
ret = kcmp_ptr ( task1 - > files , task2 - > files , KCMP_FILES ) ;
break ;
case KCMP_FS :
ret = kcmp_ptr ( task1 - > fs , task2 - > fs , KCMP_FS ) ;
break ;
case KCMP_SIGHAND :
ret = kcmp_ptr ( task1 - > sighand , task2 - > sighand , KCMP_SIGHAND ) ;
break ;
case KCMP_IO :
ret = kcmp_ptr ( task1 - > io_context , task2 - > io_context , KCMP_IO ) ;
break ;
case KCMP_SYSVSEM :
# ifdef CONFIG_SYSVIPC
ret = kcmp_ptr ( task1 - > sysvsem . undo_list ,
task2 - > sysvsem . undo_list ,
KCMP_SYSVSEM ) ;
# else
ret = - EOPNOTSUPP ;
# endif
break ;
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case KCMP_EPOLL_TFD :
ret = kcmp_epoll_target ( task1 , task2 , idx1 , ( void * ) idx2 ) ;
break ;
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default :
ret = - EINVAL ;
break ;
}
err_unlock :
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kcmp_unlock ( & task1 - > signal - > exec_update_lock ,
& task2 - > signal - > exec_update_lock ) ;
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err :
put_task_struct ( task1 ) ;
put_task_struct ( task2 ) ;
return ret ;
err_no_task :
rcu_read_unlock ( ) ;
return - ESRCH ;
}
static __init int kcmp_cookies_init ( void )
{
int i ;
get_random_bytes ( cookies , sizeof ( cookies ) ) ;
for ( i = 0 ; i < KCMP_TYPES ; i + + )
cookies [ i ] [ 1 ] | = ( ~ ( ~ 0UL > > 1 ) | 1 ) ;
return 0 ;
}
arch_initcall ( kcmp_cookies_init ) ;
