fuse: add "resolve-gids" mount option to overcome 32-groups limit

Add a --resolve-gids commandline option to the glusterfs binary. This
option gets set when executing "mount -t glusterfs -o resolve-gids ...".

This option is most useful in combination with the "acl" mount option.
POSIX ACL permission checking is done on the FUSE-client side to improve
performance (in addition to the checking on the bricks).

The fuse-bridge reads /proc/$PID/status by default, and this file
contains maximum 32 groups. Any local (client-side) permission checking
that requires more than the first 32 groups will fail.

By enabling the "resolve-gids" option, the fuse-bridge will call
getgrouplist() to retrieve all the groups from the user accessing the
mountpoint. This is comparable to how "nfs.server-aux-gids" works.

Note that when a user belongs to more than ~93 groups, the volume option
server.manage-gids needs to be enabled too. Without this option, the
RPC-layer will need to reduce the number of groups to make them fit in
the RPC-header.

Change-Id: I7ede90d0e41bcf55755cced5747fa0fb1699edb2
BUG: 1246275
Signed-off-by: Niels de Vos <ndevos@redhat.com>
Reviewed-on: http://review.gluster.org/11732
Tested-by: NetBSD Build System <jenkins@build.gluster.org>
Reviewed-by: Ravishankar N <ravishankar@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: jiffin tony Thottan <jthottan@redhat.com>
Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>

3 files changed, 86 insertions, 39 deletions

diff --git a/xlators/mount/fuse/src/fuse-bridge.c b/xlators/mount/fuse/src/fuse-bridge.c
index b67a60a76b1..d6edcb360cd 100644
--- a/xlators/mount/fuse/src/fuse-bridge.c
+++ b/xlators/mount/fuse/src/fuse-bridge.c
@@ -5427,6 +5427,8 @@ init (xlator_t *this_xl)
                 goto cleanup_exit;
         }
 
+        GF_OPTION_INIT("resolve-gids", priv->resolve_gids, bool, cleanup_exit);
+
         /* default values seemed to work fine during testing */
         GF_OPTION_INIT ("background-qlen", priv->background_qlen, int32,
                         cleanup_exit);
@@ -5665,6 +5667,10 @@ struct volume_options options[] = {
           .type = GF_OPTION_TYPE_INT,
           .default_value = "300"
         },
+        { .key = {"resolve-gids"},
+          .type = GF_OPTION_TYPE_BOOL,
+          .default_value = "false"
+        },
         { .key = {"acl"},
           .type = GF_OPTION_TYPE_BOOL,
           .default_value = "false"
diff --git a/xlators/mount/fuse/src/fuse-bridge.h b/xlators/mount/fuse/src/fuse-bridge.h
index a9705d6c654..850eeb60ea8 100644
--- a/xlators/mount/fuse/src/fuse-bridge.h
+++ b/xlators/mount/fuse/src/fuse-bridge.h
@@ -127,6 +127,9 @@ struct fuse_private {
         /* fini started, helps prevent multiple epoll worker threads
          * firing up the fini routine */
         gf_boolean_t fini_invoked;
+
+        /* resolve gid with getgrouplist() instead of /proc/%d/status */
+        gf_boolean_t resolve_gids;
 };
 typedef struct fuse_private fuse_private_t;
 
diff --git a/xlators/mount/fuse/src/fuse-helpers.c b/xlators/mount/fuse/src/fuse-helpers.c
index 1c888276eb5..22aa9b486d1 100644
--- a/xlators/mount/fuse/src/fuse-helpers.c
+++ b/xlators/mount/fuse/src/fuse-helpers.c
@@ -20,6 +20,8 @@
 #elif defined(CTL_KERN)
 #include <sys/sysctl.h>
 #endif
+#include <pwd.h>
+#include <grp.h>
 
 #include "fuse-bridge.h"
 
@@ -146,51 +148,87 @@ void
 frame_fill_groups (call_frame_t *frame)
 {
 #if defined(GF_LINUX_HOST_OS)
-        char         filename[32];
-        char         line[4096];
-        char        *ptr = NULL;
-        FILE        *fp = NULL;
-        int          idx = 0;
-        long int     id = 0;
-        char        *saveptr = NULL;
-        char        *endptr = NULL;
-        int          ret = 0;
-
-        ret = snprintf (filename, sizeof filename, "/proc/%d/status",
-                        frame->root->pid);
-        if (ret >= sizeof filename)
-                goto out;
+        xlator_t       *this          = frame->this;
+        fuse_private_t *priv          = this->private;
+        char            filename[32];
+        char            line[4096];
+        char           *ptr           = NULL;
+        FILE           *fp            = NULL;
+        int             idx           = 0;
+        long int        id            = 0;
+        char           *saveptr       = NULL;
+        char           *endptr        = NULL;
+        int             ret           = 0;
+        int             ngroups       = FUSE_MAX_AUX_GROUPS;
+        gid_t           mygroups[GF_MAX_AUX_GROUPS];
+
+        if (priv->resolve_gids) {
+                struct passwd    pwent;
+                char             mystrs[1024];
+                struct passwd   *result;
+
+                if (getpwuid_r (frame->root->uid, &pwent, mystrs,
+                                sizeof(mystrs), &result) != 0) {
+                        gf_log (this->name, GF_LOG_ERROR, "getpwuid_r(%u) "
+                                "failed", frame->root->uid);
+                        return;
+                }
 
-        fp = fopen (filename, "r");
-        if (!fp)
-                goto out;
+                ngroups = GF_MAX_AUX_GROUPS;
+                if (getgrouplist (result->pw_name, frame->root->gid, mygroups,
+                                  &ngroups) == -1) {
+                        gf_log (this->name, GF_LOG_ERROR, "could not map %s to "
+                                "group list (ngroups %d, max %d)",
+                                result->pw_name, ngroups, GF_MAX_AUX_GROUPS);
+                        return;
+                }
 
-        if (call_stack_alloc_groups (frame->root, FUSE_MAX_AUX_GROUPS) != 0)
-                goto out;
+                if (call_stack_alloc_groups (frame->root, ngroups) != 0)
+                        goto out;
 
-        while ((ptr = fgets (line, sizeof line, fp))) {
-                if (strncmp (ptr, "Groups:", 7) != 0)
-                        continue;
-
-                ptr = line + 8;
-
-                for (ptr = strtok_r (ptr, " \t\r\n", &saveptr);
-                     ptr;
-                     ptr = strtok_r (NULL, " \t\r\n", &saveptr)) {
-                        errno = 0;
-                        id = strtol (ptr, &endptr, 0);
-                        if (errno == ERANGE)
-                                break;
-                        if (!endptr || *endptr)
-                                break;
-                        frame->root->groups[idx++] = id;
-                        if (idx == FUSE_MAX_AUX_GROUPS)
-                                break;
+                /* Copy data to the frame. */
+                for (idx = 0; idx < ngroups; ++idx) {
+                        frame->root->groups[idx] = mygroups[idx];
                 }
+                frame->root->ngrps = ngroups;
+        } else {
+                ret = snprintf (filename, sizeof filename, "/proc/%d/status",
+                                frame->root->pid);
+                if (ret >= sizeof filename)
+                        goto out;
 
-                frame->root->ngrps = idx;
-                break;
+                fp = fopen (filename, "r");
+                if (!fp)
+                        goto out;
+
+                if (call_stack_alloc_groups (frame->root, ngroups) != 0)
+                        goto out;
+
+                while ((ptr = fgets (line, sizeof line, fp))) {
+                        if (strncmp (ptr, "Groups:", 7) != 0)
+                                continue;
+
+                        ptr = line + 8;
+
+                        for (ptr = strtok_r (ptr, " \t\r\n", &saveptr);
+                             ptr;
+                             ptr = strtok_r (NULL, " \t\r\n", &saveptr)) {
+                                errno = 0;
+                                id = strtol (ptr, &endptr, 0);
+                                if (errno == ERANGE)
+                                        break;
+                                if (!endptr || *endptr)
+                                        break;
+                                frame->root->groups[idx++] = id;
+                                if (idx == FUSE_MAX_AUX_GROUPS)
+                                        break;
+                        }
+
+                        frame->root->ngrps = idx;
+                        break;
+                }
         }
+
 out:
         if (fp)
                 fclose (fp);