* [PATCH] libsemanage: genhomedircon - improve handling large groups
@ 2019-02-06 19:45 Petr Lautrbach
2019-02-07 21:19 ` Nicolas Iooss
0 siblings, 1 reply; 6+ messages in thread
From: Petr Lautrbach @ 2019-02-06 19:45 UTC (permalink / raw)
To: selinux; +Cc: Petr Lautrbach
getgrnam_r() uses a preallocated buffer to store a structure containing
the broken-out fields of the record in the group database. The size of
this buffer is usually sysconf(_SC_GETGR_R_SIZE_MAX) == 1024 and it is
not enough for groups with a large number of users. In these cases,
getgrnam_r() returns -1 and sets errno to ERANGE and the caller can
retry with a larger buffer.
Fixes:
$ semanage login -a -s user_u -r s0-s0:c1.c2 '%largegroup'
libsemanage.semanage_direct_commit: semanage_genhomedircon returned error code -1. (Numerical result out of range).
OSError: Numerical result out of range
Signed-off-by: Petr Lautrbach <plautrba@redhat.com>
---
libsemanage/src/genhomedircon.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/libsemanage/src/genhomedircon.c b/libsemanage/src/genhomedircon.c
index 591941fb..ac376671 100644
--- a/libsemanage/src/genhomedircon.c
+++ b/libsemanage/src/genhomedircon.c
@@ -1077,10 +1077,20 @@ static int get_group_users(genhomedircon_settings_t * s,
const char *grname = selogin + 1;
- if (getgrnam_r(grname, &grstorage, grbuf,
- (size_t) grbuflen, &group) != 0) {
- goto cleanup;
+ errno = 0;
+ while (
+ (retval = getgrnam_r(grname, &grstorage, grbuf, (size_t) grbuflen, &group)) != 0 &&
+ errno == ERANGE
+ ) {
+ char *new_grbuf;
+ grbuflen *= 2;
+ new_grbuf = realloc(grbuf, grbuflen);
+ if (new_grbuf == NULL)
+ goto cleanup;
+ grbuf = new_grbuf;
}
+ if (retval == -1)
+ goto cleanup;
if (group == NULL) {
ERR(s->h_semanage, "Can't find group named %s\n", grname);
--
2.20.1
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] libsemanage: genhomedircon - improve handling large groups
2019-02-06 19:45 [PATCH] libsemanage: genhomedircon - improve handling large groups Petr Lautrbach
@ 2019-02-07 21:19 ` Nicolas Iooss
2019-02-08 16:46 ` Petr Lautrbach
0 siblings, 1 reply; 6+ messages in thread
From: Nicolas Iooss @ 2019-02-07 21:19 UTC (permalink / raw)
To: Petr Lautrbach; +Cc: selinux
On Wed, Feb 6, 2019 at 8:45 PM Petr Lautrbach <plautrba@redhat.com> wrote:
>
> getgrnam_r() uses a preallocated buffer to store a structure containing
> the broken-out fields of the record in the group database. The size of
> this buffer is usually sysconf(_SC_GETGR_R_SIZE_MAX) == 1024 and it is
> not enough for groups with a large number of users. In these cases,
> getgrnam_r() returns -1 and sets errno to ERANGE and the caller can
> retry with a larger buffer.
>
> Fixes:
> $ semanage login -a -s user_u -r s0-s0:c1.c2 '%largegroup'
> libsemanage.semanage_direct_commit: semanage_genhomedircon returned error code -1. (Numerical result out of range).
> OSError: Numerical result out of range
>
> Signed-off-by: Petr Lautrbach <plautrba@redhat.com>
> ---
> libsemanage/src/genhomedircon.c | 16 +++++++++++++---
> 1 file changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/libsemanage/src/genhomedircon.c b/libsemanage/src/genhomedircon.c
> index 591941fb..ac376671 100644
> --- a/libsemanage/src/genhomedircon.c
> +++ b/libsemanage/src/genhomedircon.c
> @@ -1077,10 +1077,20 @@ static int get_group_users(genhomedircon_settings_t * s,
>
> const char *grname = selogin + 1;
>
> - if (getgrnam_r(grname, &grstorage, grbuf,
> - (size_t) grbuflen, &group) != 0) {
> - goto cleanup;
> + errno = 0;
> + while (
> + (retval = getgrnam_r(grname, &grstorage, grbuf, (size_t) grbuflen, &group)) != 0 &&
> + errno == ERANGE
> + ) {
> + char *new_grbuf;
> + grbuflen *= 2;
> + new_grbuf = realloc(grbuf, grbuflen);
> + if (new_grbuf == NULL)
> + goto cleanup;
> + grbuf = new_grbuf;
> }
Hello,
When reading this for loop, I am concerned about the case where the
member list exceeds 2Go on a system with a 32-bit CPU (where
sizeof(long) = 4). Even if it seems very unlikely, if this ever
happens, the loop will become infinite. Would you agree with adding
"&& grbuflen > 0" to the condition of the while statement?
Anyway, if you do not agree, this patch looks good to me.
Acked-by: Nicolas Iooss <nicolas.iooss@m4x.org>
Thanks,
Nicolas
> + if (retval == -1)
> + goto cleanup;
>
> if (group == NULL) {
> ERR(s->h_semanage, "Can't find group named %s\n", grname);
> --
> 2.20.1
>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] libsemanage: genhomedircon - improve handling large groups
2019-02-07 21:19 ` Nicolas Iooss
@ 2019-02-08 16:46 ` Petr Lautrbach
2019-02-12 15:20 ` [PATCH v2] " Petr Lautrbach
0 siblings, 1 reply; 6+ messages in thread
From: Petr Lautrbach @ 2019-02-08 16:46 UTC (permalink / raw)
To: selinux; +Cc: Petr Lautrbach, Nicolas Iooss
Nicolas Iooss <nicolas.iooss@m4x.org> writes:
> On Wed, Feb 6, 2019 at 8:45 PM Petr Lautrbach
> <plautrba@redhat.com> wrote:
>>
>> getgrnam_r() uses a preallocated buffer to store a structure
>> containing
>> the broken-out fields of the record in the group database. The
>> size of
>> this buffer is usually sysconf(_SC_GETGR_R_SIZE_MAX) == 1024
>> and it is
>> not enough for groups with a large number of users. In these
>> cases,
>> getgrnam_r() returns -1 and sets errno to ERANGE and the caller
>> can
>> retry with a larger buffer.
>>
>> Fixes:
>> $ semanage login -a -s user_u -r s0-s0:c1.c2 '%largegroup'
>> libsemanage.semanage_direct_commit: semanage_genhomedircon
>> returned error code -1. (Numerical result out of range).
>> OSError: Numerical result out of range
>>
>> Signed-off-by: Petr Lautrbach <plautrba@redhat.com>
>> ---
>> libsemanage/src/genhomedircon.c | 16 +++++++++++++---
>> 1 file changed, 13 insertions(+), 3 deletions(-)
>>
>> diff --git a/libsemanage/src/genhomedircon.c
>> b/libsemanage/src/genhomedircon.c
>> index 591941fb..ac376671 100644
>> --- a/libsemanage/src/genhomedircon.c
>> +++ b/libsemanage/src/genhomedircon.c
>> @@ -1077,10 +1077,20 @@ static int
>> get_group_users(genhomedircon_settings_t * s,
>>
>> const char *grname = selogin + 1;
>>
>> - if (getgrnam_r(grname, &grstorage, grbuf,
>> - (size_t) grbuflen, &group) != 0) {
>> - goto cleanup;
>> + errno = 0;
>> + while (
>> + (retval = getgrnam_r(grname, &grstorage, grbuf,
>> (size_t) grbuflen, &group)) != 0 &&
>> + errno == ERANGE
>> + ) {
>> + char *new_grbuf;
>> + grbuflen *= 2;
>> + new_grbuf = realloc(grbuf, grbuflen);
>> + if (new_grbuf == NULL)
>> + goto cleanup;
>> + grbuf = new_grbuf;
>> }
>
> Hello,
> When reading this for loop, I am concerned about the case where
> the
> member list exceeds 2Go on a system with a 32-bit CPU (where
> sizeof(long) = 4). Even if it seems very unlikely, if this ever
> happens, the loop will become infinite. Would you agree with
> adding
> "&& grbuflen > 0" to the condition of the while statement?
Makes sense, I'll add it. Thanks.
> Anyway, if you do not agree, this patch looks good to me.
> Acked-by: Nicolas Iooss <nicolas.iooss@m4x.org>
>
> Thanks,
> Nicolas
>
>> + if (retval == -1)
>> + goto cleanup;
According to the man page this check is not correct. - "In case of
error, an error number is returned, and NULL is stored in
*result."
I'll fix it as well.
>> if (group == NULL) {
>> ERR(s->h_semanage, "Can't find group named
>> %s\n", grname);
>> --
>> 2.20.1
>>
^ permalink raw reply [flat|nested] 6+ messages in thread* [PATCH v2] libsemanage: genhomedircon - improve handling large groups
2019-02-08 16:46 ` Petr Lautrbach
@ 2019-02-12 15:20 ` Petr Lautrbach
2019-02-12 21:02 ` Nicolas Iooss
0 siblings, 1 reply; 6+ messages in thread
From: Petr Lautrbach @ 2019-02-12 15:20 UTC (permalink / raw)
To: selinux; +Cc: Petr Lautrbach
getgrnam_r() uses a preallocated buffer to store a structure containing
the broken-out fields of the record in the group database. The size of
this buffer is usually sysconf(_SC_GETGR_R_SIZE_MAX) == 1024 and it is
not enough for groups with a large number of users. In these cases,
getgrnam_r() returns -1 and sets errno to ERANGE and the caller can
retry with a larger buffer.
Fixes:
$ semanage login -a -s user_u -r s0-s0:c1.c2 '%largegroup'
libsemanage.semanage_direct_commit: semanage_genhomedircon returned error code -1. (Numerical result out of range).
OSError: Numerical result out of range
Signed-off-by: Petr Lautrbach <plautrba@redhat.com>
---
libsemanage/src/genhomedircon.c | 20 +++++++++++++++++---
1 file changed, 17 insertions(+), 3 deletions(-)
diff --git a/libsemanage/src/genhomedircon.c b/libsemanage/src/genhomedircon.c
index 591941fb..e5f8d371 100644
--- a/libsemanage/src/genhomedircon.c
+++ b/libsemanage/src/genhomedircon.c
@@ -1077,10 +1077,24 @@ static int get_group_users(genhomedircon_settings_t * s,
const char *grname = selogin + 1;
- if (getgrnam_r(grname, &grstorage, grbuf,
- (size_t) grbuflen, &group) != 0) {
- goto cleanup;
+ errno = 0;
+ while (
+ (retval = getgrnam_r(grname, &grstorage, grbuf, (size_t) grbuflen, &group)) != 0 &&
+ errno == ERANGE
+ ) {
+ char *new_grbuf;
+ grbuflen *= 2;
+ if (grbuflen < 0)
+ /* the member list could exceed 2Gb on a system with a 32-bit CPU (where
+ * sizeof(long) = 4) - if this ever happened, the loop would become infinite. */
+ goto cleanup;
+ new_grbuf = realloc(grbuf, grbuflen);
+ if (new_grbuf == NULL)
+ goto cleanup;
+ grbuf = new_grbuf;
}
+ if (retval != 0)
+ goto cleanup;
if (group == NULL) {
ERR(s->h_semanage, "Can't find group named %s\n", grname);
--
2.20.1
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH v2] libsemanage: genhomedircon - improve handling large groups
2019-02-12 15:20 ` [PATCH v2] " Petr Lautrbach
@ 2019-02-12 21:02 ` Nicolas Iooss
2019-02-15 13:56 ` Petr Lautrbach
0 siblings, 1 reply; 6+ messages in thread
From: Nicolas Iooss @ 2019-02-12 21:02 UTC (permalink / raw)
To: Petr Lautrbach; +Cc: selinux
On Tue, Feb 12, 2019 at 4:20 PM Petr Lautrbach <plautrba@redhat.com> wrote:
>
> getgrnam_r() uses a preallocated buffer to store a structure containing
> the broken-out fields of the record in the group database. The size of
> this buffer is usually sysconf(_SC_GETGR_R_SIZE_MAX) == 1024 and it is
> not enough for groups with a large number of users. In these cases,
> getgrnam_r() returns -1 and sets errno to ERANGE and the caller can
> retry with a larger buffer.
>
> Fixes:
> $ semanage login -a -s user_u -r s0-s0:c1.c2 '%largegroup'
> libsemanage.semanage_direct_commit: semanage_genhomedircon returned error code -1. (Numerical result out of range).
> OSError: Numerical result out of range
>
> Signed-off-by: Petr Lautrbach <plautrba@redhat.com>
Acked-by: Nicolas Iooss <nicolas.iooss@m4x.org>
> ---
> libsemanage/src/genhomedircon.c | 20 +++++++++++++++++---
> 1 file changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/libsemanage/src/genhomedircon.c b/libsemanage/src/genhomedircon.c
> index 591941fb..e5f8d371 100644
> --- a/libsemanage/src/genhomedircon.c
> +++ b/libsemanage/src/genhomedircon.c
> @@ -1077,10 +1077,24 @@ static int get_group_users(genhomedircon_settings_t * s,
>
> const char *grname = selogin + 1;
>
> - if (getgrnam_r(grname, &grstorage, grbuf,
> - (size_t) grbuflen, &group) != 0) {
> - goto cleanup;
> + errno = 0;
> + while (
> + (retval = getgrnam_r(grname, &grstorage, grbuf, (size_t) grbuflen, &group)) != 0 &&
> + errno == ERANGE
> + ) {
> + char *new_grbuf;
> + grbuflen *= 2;
> + if (grbuflen < 0)
> + /* the member list could exceed 2Gb on a system with a 32-bit CPU (where
> + * sizeof(long) = 4) - if this ever happened, the loop would become infinite. */
> + goto cleanup;
> + new_grbuf = realloc(grbuf, grbuflen);
> + if (new_grbuf == NULL)
> + goto cleanup;
> + grbuf = new_grbuf;
> }
> + if (retval != 0)
> + goto cleanup;
>
> if (group == NULL) {
> ERR(s->h_semanage, "Can't find group named %s\n", grname);
> --
> 2.20.1
>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH v2] libsemanage: genhomedircon - improve handling large groups
2019-02-12 21:02 ` Nicolas Iooss
@ 2019-02-15 13:56 ` Petr Lautrbach
0 siblings, 0 replies; 6+ messages in thread
From: Petr Lautrbach @ 2019-02-15 13:56 UTC (permalink / raw)
To: selinux; +Cc: Nicolas Iooss
Nicolas Iooss <nicolas.iooss@m4x.org> writes:
> On Tue, Feb 12, 2019 at 4:20 PM Petr Lautrbach <plautrba@redhat.com> wrote:
>>
>> getgrnam_r() uses a preallocated buffer to store a structure containing
>> the broken-out fields of the record in the group database. The size of
>> this buffer is usually sysconf(_SC_GETGR_R_SIZE_MAX) == 1024 and it is
>> not enough for groups with a large number of users. In these cases,
>> getgrnam_r() returns -1 and sets errno to ERANGE and the caller can
>> retry with a larger buffer.
>>
>> Fixes:
>> $ semanage login -a -s user_u -r s0-s0:c1.c2 '%largegroup'
>> libsemanage.semanage_direct_commit: semanage_genhomedircon returned error code -1. (Numerical result out of range).
>> OSError: Numerical result out of range
>>
>> Signed-off-by: Petr Lautrbach <plautrba@redhat.com>
>
> Acked-by: Nicolas Iooss <nicolas.iooss@m4x.org>
Merged.
>> ---
>> libsemanage/src/genhomedircon.c | 20 +++++++++++++++++---
>> 1 file changed, 17 insertions(+), 3 deletions(-)
>>
>> diff --git a/libsemanage/src/genhomedircon.c b/libsemanage/src/genhomedircon.c
>> index 591941fb..e5f8d371 100644
>> --- a/libsemanage/src/genhomedircon.c
>> +++ b/libsemanage/src/genhomedircon.c
>> @@ -1077,10 +1077,24 @@ static int get_group_users(genhomedircon_settings_t * s,
>>
>> const char *grname = selogin + 1;
>>
>> - if (getgrnam_r(grname, &grstorage, grbuf,
>> - (size_t) grbuflen, &group) != 0) {
>> - goto cleanup;
>> + errno = 0;
>> + while (
>> + (retval = getgrnam_r(grname, &grstorage, grbuf, (size_t) grbuflen, &group)) != 0 &&
>> + errno == ERANGE
>> + ) {
>> + char *new_grbuf;
>> + grbuflen *= 2;
>> + if (grbuflen < 0)
>> + /* the member list could exceed 2Gb on a system with a 32-bit CPU (where
>> + * sizeof(long) = 4) - if this ever happened, the loop would become infinite. */
>> + goto cleanup;
>> + new_grbuf = realloc(grbuf, grbuflen);
>> + if (new_grbuf == NULL)
>> + goto cleanup;
>> + grbuf = new_grbuf;
>> }
>> + if (retval != 0)
>> + goto cleanup;
>>
>> if (group == NULL) {
>> ERR(s->h_semanage, "Can't find group named %s\n", grname);
>> --
>> 2.20.1
>>
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2019-02-15 13:56 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2019-02-06 19:45 [PATCH] libsemanage: genhomedircon - improve handling large groups Petr Lautrbach
2019-02-07 21:19 ` Nicolas Iooss
2019-02-08 16:46 ` Petr Lautrbach
2019-02-12 15:20 ` [PATCH v2] " Petr Lautrbach
2019-02-12 21:02 ` Nicolas Iooss
2019-02-15 13:56 ` Petr Lautrbach
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