diff mbox series

Add guards around [nfsidmap] usages of [sysconf].

Message ID 20240530071725.70043-1-b.tataroiu@gmail.com (mailing list archive)
State New
Headers show
Series Add guards around [nfsidmap] usages of [sysconf]. | expand

Commit Message

Bogdan-Cristian Tătăroiu May 30, 2024, 7:17 a.m. UTC
sysconf(_SC_GETPW_R_SIZE_MAX) and sysconf(_SC_GETGR_R_SIZE_MAX)
return -1 on musl, which causes either segmentation faults or ENOMEM
errors.

Replace all usages of sysconf with dedicated methods that guard against
a result of -1.

Signed-off-by: Bogdan-Cristian Tătăroiu <b.tataroiu@gmail.com>
---
 support/nfsidmap/gums.c             |  4 ++--
 support/nfsidmap/libnfsidmap.c      |  4 ++--
 support/nfsidmap/nfsidmap_common.c  | 16 ++++++++++++++++
 support/nfsidmap/nfsidmap_private.h |  2 ++
 support/nfsidmap/nss.c              |  8 ++++----
 support/nfsidmap/regex.c            |  9 +++++----
 support/nfsidmap/static.c           |  5 +++--
 7 files changed, 34 insertions(+), 14 deletions(-)

Comments

Steve Dickson June 17, 2024, 7:51 p.m. UTC | #1
On 5/30/24 2:17 AM, Bogdan-Cristian Tătăroiu wrote:
> sysconf(_SC_GETPW_R_SIZE_MAX) and sysconf(_SC_GETGR_R_SIZE_MAX)
> return -1 on musl, which causes either segmentation faults or ENOMEM
> errors.
Actually sysconf() returns EINVAL not -1 since the return
value is a size_t (unsigned long). So I needed to change

     size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
     if (buflen == EINVAL) <<< this from -1 to EINVAL
         buflen = 16384;
     return buflen;

Good with that? Will this work with musl?

steved.

> 
> Replace all usages of sysconf with dedicated methods that guard against
> a result of -1.
> 
> Signed-off-by: Bogdan-Cristian Tătăroiu <b.tataroiu@gmail.com>
> ---
>   support/nfsidmap/gums.c             |  4 ++--
>   support/nfsidmap/libnfsidmap.c      |  4 ++--
>   support/nfsidmap/nfsidmap_common.c  | 16 ++++++++++++++++
>   support/nfsidmap/nfsidmap_private.h |  2 ++
>   support/nfsidmap/nss.c              |  8 ++++----
>   support/nfsidmap/regex.c            |  9 +++++----
>   support/nfsidmap/static.c           |  5 +++--
>   7 files changed, 34 insertions(+), 14 deletions(-)
> 
> diff --git a/support/nfsidmap/gums.c b/support/nfsidmap/gums.c
> index 1d6eb318..e94a4c50 100644
> --- a/support/nfsidmap/gums.c
> +++ b/support/nfsidmap/gums.c
> @@ -475,7 +475,7 @@ static int translate_to_uid(char *local_uid, uid_t *uid, uid_t *gid)
>   	int ret = -1;
>   	struct passwd *pw = NULL;
>   	struct pwbuf *buf = NULL;
> -	size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
> +	size_t buflen = get_pwnam_buflen();
>   
>   	buf = malloc(sizeof(*buf) + buflen);
>   	if (buf == NULL)
> @@ -501,7 +501,7 @@ static int translate_to_gid(char *local_gid, uid_t *gid)
>   	struct group *gr = NULL;
>   	struct group grbuf;
>   	char *buf = NULL;
> -	size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
> +	size_t buflen = get_grnam_buflen();
>   	int ret = -1;
>   
>   	do {
> diff --git a/support/nfsidmap/libnfsidmap.c b/support/nfsidmap/libnfsidmap.c
> index f8c36480..e1475879 100644
> --- a/support/nfsidmap/libnfsidmap.c
> +++ b/support/nfsidmap/libnfsidmap.c
> @@ -457,7 +457,7 @@ int nfs4_init_name_mapping(char *conffile)
>   
>   	nobody_user = conf_get_str("Mapping", "Nobody-User");
>   	if (nobody_user) {
> -		size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
> +		size_t buflen = get_pwnam_buflen();
>   		struct passwd *buf;
>   		struct passwd *pw = NULL;
>   		int err;
> @@ -478,7 +478,7 @@ int nfs4_init_name_mapping(char *conffile)
>   
>   	nobody_group = conf_get_str("Mapping", "Nobody-Group");
>   	if (nobody_group) {
> -		size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
> +		size_t buflen = get_grnam_buflen();
>   		struct group *buf;
>   		struct group *gr = NULL;
>   		int err;
> diff --git a/support/nfsidmap/nfsidmap_common.c b/support/nfsidmap/nfsidmap_common.c
> index 4d2cb14f..310c68f0 100644
> --- a/support/nfsidmap/nfsidmap_common.c
> +++ b/support/nfsidmap/nfsidmap_common.c
> @@ -116,3 +116,19 @@ int get_reformat_group(void)
>   
>   	return reformat_group;
>   }
> +
> +size_t get_pwnam_buflen(void)
> +{
> +	size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
> +	if (buflen == -1)
> +		buflen = 16384;
> +	return buflen;
> +}
> +
> +size_t get_grnam_buflen(void)
> +{
> +	size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
> +	if (buflen == -1)
> +		buflen = 16384;
> +	return buflen;
> +}
> diff --git a/support/nfsidmap/nfsidmap_private.h b/support/nfsidmap/nfsidmap_private.h
> index a5cb6dda..234ca9d4 100644
> --- a/support/nfsidmap/nfsidmap_private.h
> +++ b/support/nfsidmap/nfsidmap_private.h
> @@ -40,6 +40,8 @@ struct conf_list *get_local_realms(void);
>   void free_local_realms(void);
>   int get_nostrip(void);
>   int get_reformat_group(void);
> +size_t get_pwnam_buflen(void);
> +size_t get_grnam_buflen(void);
>   
>   typedef enum {
>   	IDTYPE_USER = 1,
> diff --git a/support/nfsidmap/nss.c b/support/nfsidmap/nss.c
> index 0f43076e..3fc045dc 100644
> --- a/support/nfsidmap/nss.c
> +++ b/support/nfsidmap/nss.c
> @@ -91,7 +91,7 @@ static int nss_uid_to_name(uid_t uid, char *domain, char *name, size_t len)
>   	struct passwd *pw = NULL;
>   	struct passwd pwbuf;
>   	char *buf;
> -	size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
> +	size_t buflen = get_pwnam_buflen();
>   	int err = -ENOMEM;
>   
>   	buf = malloc(buflen);
> @@ -119,7 +119,7 @@ static int nss_gid_to_name(gid_t gid, char *domain, char *name, size_t len)
>   	struct group *gr = NULL;
>   	struct group grbuf;
>   	char *buf;
> -	size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
> +	size_t buflen = get_grnam_buflen();
>   	int err;
>   
>   	if (domain == NULL)
> @@ -192,7 +192,7 @@ static struct passwd *nss_getpwnam(const char *name, const char *domain,
>   {
>   	struct passwd *pw;
>   	struct pwbuf *buf;
> -	size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
> +	size_t buflen = get_pwnam_buflen();
>   	char *localname;
>   	int err = ENOMEM;
>   
> @@ -301,7 +301,7 @@ static int _nss_name_to_gid(char *name, gid_t *gid, int dostrip)
>   	struct group *gr = NULL;
>   	struct group grbuf;
>   	char *buf, *domain;
> -	size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
> +	size_t buflen = get_grnam_buflen();
>   	int err = -EINVAL;
>   	char *localname = NULL;
>   	char *ref_name = NULL;
> diff --git a/support/nfsidmap/regex.c b/support/nfsidmap/regex.c
> index 8424179f..ea094b95 100644
> --- a/support/nfsidmap/regex.c
> +++ b/support/nfsidmap/regex.c
> @@ -46,6 +46,7 @@
>   
>   #include "nfsidmap.h"
>   #include "nfsidmap_plugin.h"
> +#include "nfsidmap_private.h"
>   
>   #define CONFIG_GET_STRING nfsidmap_config_get
>   extern const char *nfsidmap_config_get(const char *, const char *);
> @@ -95,7 +96,7 @@ static struct passwd *regex_getpwnam(const char *name, const char *UNUSED(domain
>   {
>   	struct passwd *pw;
>   	struct pwbuf *buf;
> -	size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
> +	size_t buflen = get_pwnam_buflen();
>   	char *localname;
>   	size_t namelen;
>   	int err;
> @@ -175,7 +176,7 @@ static struct group *regex_getgrnam(const char *name, const char *UNUSED(domain)
>   {
>   	struct group *gr;
>   	struct grbuf *buf;
> -	size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
> +	size_t buflen = get_grnam_buflen();
>   	char *localgroup;
>   	char *groupname;
>   	size_t namelen;
> @@ -366,7 +367,7 @@ static int regex_uid_to_name(uid_t uid, char *domain, char *name, size_t len)
>   	struct passwd *pw = NULL;
>   	struct passwd pwbuf;
>   	char *buf;
> -	size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
> +	size_t buflen = get_pwnam_buflen();
>   	int err = -ENOMEM;
>   
>   	buf = malloc(buflen);
> @@ -392,7 +393,7 @@ static int regex_gid_to_name(gid_t gid, char *UNUSED(domain), char *name, size_t
>   	struct group grbuf;
>   	char *buf;
>       const char *name_prefix;
> -	size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
> +	size_t buflen = get_grnam_buflen();
>   	int err;
>       char * groupname = NULL;
>   
> diff --git a/support/nfsidmap/static.c b/support/nfsidmap/static.c
> index 8ac4a398..395cac06 100644
> --- a/support/nfsidmap/static.c
> +++ b/support/nfsidmap/static.c
> @@ -44,6 +44,7 @@
>   #include "conffile.h"
>   #include "nfsidmap.h"
>   #include "nfsidmap_plugin.h"
> +#include "nfsidmap_private.h"
>   
>   /*
>    * Static Translation Methods
> @@ -98,7 +99,7 @@ static struct passwd *static_getpwnam(const char *name,
>   {
>   	struct passwd *pw;
>   	struct pwbuf *buf;
> -	size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
> +	size_t buflen = get_pwnam_buflen();
>   	char *localname;
>   	int err;
>   
> @@ -149,7 +150,7 @@ static struct group *static_getgrnam(const char *name,
>   {
>   	struct group *gr;
>   	struct grbuf *buf;
> -	size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
> +	size_t buflen = get_grnam_buflen();
>   	char *localgroup;
>   	int err;
>
Steve Dickson Nov. 9, 2024, 6:25 p.m. UTC | #2
On 6/17/24 2:51 PM, Steve Dickson wrote:
> 
> 
> On 5/30/24 2:17 AM, Bogdan-Cristian Tătăroiu wrote:
>> sysconf(_SC_GETPW_R_SIZE_MAX) and sysconf(_SC_GETGR_R_SIZE_MAX)
>> return -1 on musl, which causes either segmentation faults or ENOMEM
>> errors.
> Actually sysconf() returns EINVAL not -1 since the return
> value is a size_t (unsigned long). So I needed to change
> 
>      size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
>      if (buflen == EINVAL) <<< this from -1 to EINVAL
>          buflen = 16384;
>      return buflen;
> 
> Good with that? Will this work with musl?
Just found this on my todo list... Still
interest in  have these patch committed?

steved.

> 
> steved.
> 
>>
>> Replace all usages of sysconf with dedicated methods that guard against
>> a result of -1.
>>
>> Signed-off-by: Bogdan-Cristian Tătăroiu <b.tataroiu@gmail.com>
>> ---
>>   support/nfsidmap/gums.c             |  4 ++--
>>   support/nfsidmap/libnfsidmap.c      |  4 ++--
>>   support/nfsidmap/nfsidmap_common.c  | 16 ++++++++++++++++
>>   support/nfsidmap/nfsidmap_private.h |  2 ++
>>   support/nfsidmap/nss.c              |  8 ++++----
>>   support/nfsidmap/regex.c            |  9 +++++----
>>   support/nfsidmap/static.c           |  5 +++--
>>   7 files changed, 34 insertions(+), 14 deletions(-)
>>
>> diff --git a/support/nfsidmap/gums.c b/support/nfsidmap/gums.c
>> index 1d6eb318..e94a4c50 100644
>> --- a/support/nfsidmap/gums.c
>> +++ b/support/nfsidmap/gums.c
>> @@ -475,7 +475,7 @@ static int translate_to_uid(char *local_uid, uid_t 
>> *uid, uid_t *gid)
>>       int ret = -1;
>>       struct passwd *pw = NULL;
>>       struct pwbuf *buf = NULL;
>> -    size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
>> +    size_t buflen = get_pwnam_buflen();
>>       buf = malloc(sizeof(*buf) + buflen);
>>       if (buf == NULL)
>> @@ -501,7 +501,7 @@ static int translate_to_gid(char *local_gid, uid_t 
>> *gid)
>>       struct group *gr = NULL;
>>       struct group grbuf;
>>       char *buf = NULL;
>> -    size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
>> +    size_t buflen = get_grnam_buflen();
>>       int ret = -1;
>>       do {
>> diff --git a/support/nfsidmap/libnfsidmap.c b/support/nfsidmap/ 
>> libnfsidmap.c
>> index f8c36480..e1475879 100644
>> --- a/support/nfsidmap/libnfsidmap.c
>> +++ b/support/nfsidmap/libnfsidmap.c
>> @@ -457,7 +457,7 @@ int nfs4_init_name_mapping(char *conffile)
>>       nobody_user = conf_get_str("Mapping", "Nobody-User");
>>       if (nobody_user) {
>> -        size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
>> +        size_t buflen = get_pwnam_buflen();
>>           struct passwd *buf;
>>           struct passwd *pw = NULL;
>>           int err;
>> @@ -478,7 +478,7 @@ int nfs4_init_name_mapping(char *conffile)
>>       nobody_group = conf_get_str("Mapping", "Nobody-Group");
>>       if (nobody_group) {
>> -        size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
>> +        size_t buflen = get_grnam_buflen();
>>           struct group *buf;
>>           struct group *gr = NULL;
>>           int err;
>> diff --git a/support/nfsidmap/nfsidmap_common.c b/support/nfsidmap/ 
>> nfsidmap_common.c
>> index 4d2cb14f..310c68f0 100644
>> --- a/support/nfsidmap/nfsidmap_common.c
>> +++ b/support/nfsidmap/nfsidmap_common.c
>> @@ -116,3 +116,19 @@ int get_reformat_group(void)
>>       return reformat_group;
>>   }
>> +
>> +size_t get_pwnam_buflen(void)
>> +{
>> +    size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
>> +    if (buflen == -1)
>> +        buflen = 16384;
>> +    return buflen;
>> +}
>> +
>> +size_t get_grnam_buflen(void)
>> +{
>> +    size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
>> +    if (buflen == -1)
>> +        buflen = 16384;
>> +    return buflen;
>> +}
>> diff --git a/support/nfsidmap/nfsidmap_private.h b/support/nfsidmap/ 
>> nfsidmap_private.h
>> index a5cb6dda..234ca9d4 100644
>> --- a/support/nfsidmap/nfsidmap_private.h
>> +++ b/support/nfsidmap/nfsidmap_private.h
>> @@ -40,6 +40,8 @@ struct conf_list *get_local_realms(void);
>>   void free_local_realms(void);
>>   int get_nostrip(void);
>>   int get_reformat_group(void);
>> +size_t get_pwnam_buflen(void);
>> +size_t get_grnam_buflen(void);
>>   typedef enum {
>>       IDTYPE_USER = 1,
>> diff --git a/support/nfsidmap/nss.c b/support/nfsidmap/nss.c
>> index 0f43076e..3fc045dc 100644
>> --- a/support/nfsidmap/nss.c
>> +++ b/support/nfsidmap/nss.c
>> @@ -91,7 +91,7 @@ static int nss_uid_to_name(uid_t uid, char *domain, 
>> char *name, size_t len)
>>       struct passwd *pw = NULL;
>>       struct passwd pwbuf;
>>       char *buf;
>> -    size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
>> +    size_t buflen = get_pwnam_buflen();
>>       int err = -ENOMEM;
>>       buf = malloc(buflen);
>> @@ -119,7 +119,7 @@ static int nss_gid_to_name(gid_t gid, char 
>> *domain, char *name, size_t len)
>>       struct group *gr = NULL;
>>       struct group grbuf;
>>       char *buf;
>> -    size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
>> +    size_t buflen = get_grnam_buflen();
>>       int err;
>>       if (domain == NULL)
>> @@ -192,7 +192,7 @@ static struct passwd *nss_getpwnam(const char 
>> *name, const char *domain,
>>   {
>>       struct passwd *pw;
>>       struct pwbuf *buf;
>> -    size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
>> +    size_t buflen = get_pwnam_buflen();
>>       char *localname;
>>       int err = ENOMEM;
>> @@ -301,7 +301,7 @@ static int _nss_name_to_gid(char *name, gid_t 
>> *gid, int dostrip)
>>       struct group *gr = NULL;
>>       struct group grbuf;
>>       char *buf, *domain;
>> -    size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
>> +    size_t buflen = get_grnam_buflen();
>>       int err = -EINVAL;
>>       char *localname = NULL;
>>       char *ref_name = NULL;
>> diff --git a/support/nfsidmap/regex.c b/support/nfsidmap/regex.c
>> index 8424179f..ea094b95 100644
>> --- a/support/nfsidmap/regex.c
>> +++ b/support/nfsidmap/regex.c
>> @@ -46,6 +46,7 @@
>>   #include "nfsidmap.h"
>>   #include "nfsidmap_plugin.h"
>> +#include "nfsidmap_private.h"
>>   #define CONFIG_GET_STRING nfsidmap_config_get
>>   extern const char *nfsidmap_config_get(const char *, const char *);
>> @@ -95,7 +96,7 @@ static struct passwd *regex_getpwnam(const char 
>> *name, const char *UNUSED(domain
>>   {
>>       struct passwd *pw;
>>       struct pwbuf *buf;
>> -    size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
>> +    size_t buflen = get_pwnam_buflen();
>>       char *localname;
>>       size_t namelen;
>>       int err;
>> @@ -175,7 +176,7 @@ static struct group *regex_getgrnam(const char 
>> *name, const char *UNUSED(domain)
>>   {
>>       struct group *gr;
>>       struct grbuf *buf;
>> -    size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
>> +    size_t buflen = get_grnam_buflen();
>>       char *localgroup;
>>       char *groupname;
>>       size_t namelen;
>> @@ -366,7 +367,7 @@ static int regex_uid_to_name(uid_t uid, char 
>> *domain, char *name, size_t len)
>>       struct passwd *pw = NULL;
>>       struct passwd pwbuf;
>>       char *buf;
>> -    size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
>> +    size_t buflen = get_pwnam_buflen();
>>       int err = -ENOMEM;
>>       buf = malloc(buflen);
>> @@ -392,7 +393,7 @@ static int regex_gid_to_name(gid_t gid, char 
>> *UNUSED(domain), char *name, size_t
>>       struct group grbuf;
>>       char *buf;
>>       const char *name_prefix;
>> -    size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
>> +    size_t buflen = get_grnam_buflen();
>>       int err;
>>       char * groupname = NULL;
>> diff --git a/support/nfsidmap/static.c b/support/nfsidmap/static.c
>> index 8ac4a398..395cac06 100644
>> --- a/support/nfsidmap/static.c
>> +++ b/support/nfsidmap/static.c
>> @@ -44,6 +44,7 @@
>>   #include "conffile.h"
>>   #include "nfsidmap.h"
>>   #include "nfsidmap_plugin.h"
>> +#include "nfsidmap_private.h"
>>   /*
>>    * Static Translation Methods
>> @@ -98,7 +99,7 @@ static struct passwd *static_getpwnam(const char *name,
>>   {
>>       struct passwd *pw;
>>       struct pwbuf *buf;
>> -    size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
>> +    size_t buflen = get_pwnam_buflen();
>>       char *localname;
>>       int err;
>> @@ -149,7 +150,7 @@ static struct group *static_getgrnam(const char 
>> *name,
>>   {
>>       struct group *gr;
>>       struct grbuf *buf;
>> -    size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
>> +    size_t buflen = get_grnam_buflen();
>>       char *localgroup;
>>       int err;
diff mbox series

Patch

diff --git a/support/nfsidmap/gums.c b/support/nfsidmap/gums.c
index 1d6eb318..e94a4c50 100644
--- a/support/nfsidmap/gums.c
+++ b/support/nfsidmap/gums.c
@@ -475,7 +475,7 @@  static int translate_to_uid(char *local_uid, uid_t *uid, uid_t *gid)
 	int ret = -1;
 	struct passwd *pw = NULL;
 	struct pwbuf *buf = NULL;
-	size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
+	size_t buflen = get_pwnam_buflen();
 
 	buf = malloc(sizeof(*buf) + buflen);
 	if (buf == NULL)
@@ -501,7 +501,7 @@  static int translate_to_gid(char *local_gid, uid_t *gid)
 	struct group *gr = NULL;
 	struct group grbuf;
 	char *buf = NULL;
-	size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
+	size_t buflen = get_grnam_buflen();
 	int ret = -1;
 
 	do {
diff --git a/support/nfsidmap/libnfsidmap.c b/support/nfsidmap/libnfsidmap.c
index f8c36480..e1475879 100644
--- a/support/nfsidmap/libnfsidmap.c
+++ b/support/nfsidmap/libnfsidmap.c
@@ -457,7 +457,7 @@  int nfs4_init_name_mapping(char *conffile)
 
 	nobody_user = conf_get_str("Mapping", "Nobody-User");
 	if (nobody_user) {
-		size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
+		size_t buflen = get_pwnam_buflen();
 		struct passwd *buf;
 		struct passwd *pw = NULL;
 		int err;
@@ -478,7 +478,7 @@  int nfs4_init_name_mapping(char *conffile)
 
 	nobody_group = conf_get_str("Mapping", "Nobody-Group");
 	if (nobody_group) {
-		size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
+		size_t buflen = get_grnam_buflen();
 		struct group *buf;
 		struct group *gr = NULL;
 		int err;
diff --git a/support/nfsidmap/nfsidmap_common.c b/support/nfsidmap/nfsidmap_common.c
index 4d2cb14f..310c68f0 100644
--- a/support/nfsidmap/nfsidmap_common.c
+++ b/support/nfsidmap/nfsidmap_common.c
@@ -116,3 +116,19 @@  int get_reformat_group(void)
 
 	return reformat_group;
 }
+
+size_t get_pwnam_buflen(void)
+{
+	size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
+	if (buflen == -1)
+		buflen = 16384;
+	return buflen;
+}
+
+size_t get_grnam_buflen(void)
+{
+	size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
+	if (buflen == -1)
+		buflen = 16384;
+	return buflen;
+}
diff --git a/support/nfsidmap/nfsidmap_private.h b/support/nfsidmap/nfsidmap_private.h
index a5cb6dda..234ca9d4 100644
--- a/support/nfsidmap/nfsidmap_private.h
+++ b/support/nfsidmap/nfsidmap_private.h
@@ -40,6 +40,8 @@  struct conf_list *get_local_realms(void);
 void free_local_realms(void);
 int get_nostrip(void);
 int get_reformat_group(void);
+size_t get_pwnam_buflen(void);
+size_t get_grnam_buflen(void);
 
 typedef enum {
 	IDTYPE_USER = 1,
diff --git a/support/nfsidmap/nss.c b/support/nfsidmap/nss.c
index 0f43076e..3fc045dc 100644
--- a/support/nfsidmap/nss.c
+++ b/support/nfsidmap/nss.c
@@ -91,7 +91,7 @@  static int nss_uid_to_name(uid_t uid, char *domain, char *name, size_t len)
 	struct passwd *pw = NULL;
 	struct passwd pwbuf;
 	char *buf;
-	size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
+	size_t buflen = get_pwnam_buflen();
 	int err = -ENOMEM;
 
 	buf = malloc(buflen);
@@ -119,7 +119,7 @@  static int nss_gid_to_name(gid_t gid, char *domain, char *name, size_t len)
 	struct group *gr = NULL;
 	struct group grbuf;
 	char *buf;
-	size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
+	size_t buflen = get_grnam_buflen();
 	int err;
 
 	if (domain == NULL)
@@ -192,7 +192,7 @@  static struct passwd *nss_getpwnam(const char *name, const char *domain,
 {
 	struct passwd *pw;
 	struct pwbuf *buf;
-	size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
+	size_t buflen = get_pwnam_buflen();
 	char *localname;
 	int err = ENOMEM;
 
@@ -301,7 +301,7 @@  static int _nss_name_to_gid(char *name, gid_t *gid, int dostrip)
 	struct group *gr = NULL;
 	struct group grbuf;
 	char *buf, *domain;
-	size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
+	size_t buflen = get_grnam_buflen();
 	int err = -EINVAL;
 	char *localname = NULL;
 	char *ref_name = NULL;
diff --git a/support/nfsidmap/regex.c b/support/nfsidmap/regex.c
index 8424179f..ea094b95 100644
--- a/support/nfsidmap/regex.c
+++ b/support/nfsidmap/regex.c
@@ -46,6 +46,7 @@ 
 
 #include "nfsidmap.h"
 #include "nfsidmap_plugin.h"
+#include "nfsidmap_private.h"
 
 #define CONFIG_GET_STRING nfsidmap_config_get
 extern const char *nfsidmap_config_get(const char *, const char *);
@@ -95,7 +96,7 @@  static struct passwd *regex_getpwnam(const char *name, const char *UNUSED(domain
 {
 	struct passwd *pw;
 	struct pwbuf *buf;
-	size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
+	size_t buflen = get_pwnam_buflen();
 	char *localname;
 	size_t namelen;
 	int err;
@@ -175,7 +176,7 @@  static struct group *regex_getgrnam(const char *name, const char *UNUSED(domain)
 {
 	struct group *gr;
 	struct grbuf *buf;
-	size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
+	size_t buflen = get_grnam_buflen();
 	char *localgroup;
 	char *groupname;
 	size_t namelen;
@@ -366,7 +367,7 @@  static int regex_uid_to_name(uid_t uid, char *domain, char *name, size_t len)
 	struct passwd *pw = NULL;
 	struct passwd pwbuf;
 	char *buf;
-	size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
+	size_t buflen = get_pwnam_buflen();
 	int err = -ENOMEM;
 
 	buf = malloc(buflen);
@@ -392,7 +393,7 @@  static int regex_gid_to_name(gid_t gid, char *UNUSED(domain), char *name, size_t
 	struct group grbuf;
 	char *buf;
     const char *name_prefix;
-	size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
+	size_t buflen = get_grnam_buflen();
 	int err;
     char * groupname = NULL;
 
diff --git a/support/nfsidmap/static.c b/support/nfsidmap/static.c
index 8ac4a398..395cac06 100644
--- a/support/nfsidmap/static.c
+++ b/support/nfsidmap/static.c
@@ -44,6 +44,7 @@ 
 #include "conffile.h"
 #include "nfsidmap.h"
 #include "nfsidmap_plugin.h"
+#include "nfsidmap_private.h"
 
 /*
  * Static Translation Methods
@@ -98,7 +99,7 @@  static struct passwd *static_getpwnam(const char *name,
 {
 	struct passwd *pw;
 	struct pwbuf *buf;
-	size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
+	size_t buflen = get_pwnam_buflen();
 	char *localname;
 	int err;
 
@@ -149,7 +150,7 @@  static struct group *static_getgrnam(const char *name,
 {
 	struct group *gr;
 	struct grbuf *buf;
-	size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
+	size_t buflen = get_grnam_buflen();
 	char *localgroup;
 	int err;