Re: [PATCH] Add guards around [nfsidmap] usages of [sysconf].

Steve Dickson <steved@xxxxxxxxxx> · Mon, 17 Jun 2024 14:51:48 -0500

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@xxxxxxxxx>
---
  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;
  








