eacces_error_get*() works now properly when process's real uid != effective uid.

--HG--
branch : HEAD

diff --git a/src/lib/eacces-error.c b/src/lib/eacces-error.c
index 94644ac269b63654e7e555d84dec9f6539fdb073..dd65ddc0934fb0a6619f52bbd7d854fba48e5835 100644 (file)
--- a/src/lib/eacces-error.c
+++ b/src/lib/eacces-error.c
@@ -2,6 +2,7 @@
 
 #include "lib.h"
 #include "str.h"
+#include "restrict-access.h"
 #include "eacces-error.h"
 
 #include <sys/stat.h>
@@ -9,6 +10,76 @@
 #include <pwd.h>
 #include <grp.h>
 
+static bool is_in_group(gid_t gid)
+{
+       const gid_t *gids;
+       unsigned int i, count;
+
+       if (getegid() == gid)
+               return TRUE;
+
+       gids = restrict_get_groups_list(&count);
+       for (i = 0; i < count; i++) {
+               if (gids[i] == gid)
+                       return TRUE;
+       }
+       return FALSE;
+}
+
+static int test_access(const char *path, int mode, string_t *errmsg)
+{
+       struct stat st;
+
+       if (getuid() == geteuid()) {
+               if (access(path, mode) == 0)
+                       return 0;
+
+               if (errno != EACCES) {
+                       str_printfa(errmsg, " access(%s, %d) failed: %m",
+                                   path, mode);
+               }
+               return -1;
+       } 
+
+       /* access() uses real uid, not effective uid.
+          we'll have to do these checks manually. */
+       switch (mode) {
+       case X_OK:
+               if (stat(t_strconcat(path, "/test", NULL), &st) == 0)
+                       return 0;
+               if (errno == ENOENT || errno == ENOTDIR)
+                       return 0;
+               if (errno != EACCES)
+                       str_printfa(errmsg, " stat(%s/test) failed: %m", path);
+               return -1;
+       case R_OK:
+               mode = 04;
+               break;
+       case W_OK:
+               mode = 02;
+               break;
+       default:
+               i_unreached();
+       }
+
+       if (stat(path, &st) < 0) {
+               str_printfa(errmsg, " stat(%s) failed: %m", path);
+               return -1;
+       }
+
+       if (st.st_uid == geteuid())
+               st.st_mode = (st.st_mode & 0700) >> 6;
+       else if (is_in_group(st.st_gid))
+               st.st_mode = (st.st_mode & 0070) >> 3;
+       else
+               st.st_mode = (st.st_mode & 0007);
+
+       if ((st.st_mode & mode) != 0)
+               return 0;
+       errno = EACCES;
+       return -1;
+}
+
 static const char *
 eacces_error_get_full(const char *func, const char *path, bool creating)
 {
@@ -16,7 +87,7 @@ eacces_error_get_full(const char *func, const char *path, bool creating)
        const struct passwd *pw;
        const struct group *group;
        string_t *errmsg;
-       struct stat st;
+       struct stat st, dir_st;
        int ret = -1;
 
        errmsg = t_str_new(256);
@@ -49,25 +120,21 @@ eacces_error_get_full(const char *func, const char *path, bool creating)
                }
                prev_path = dir;
                dir = "/";
+               dir_st = st;
        }
 
        if (ret == 0) {
                /* dir is the first parent directory we can stat() */
-               if (access(dir, X_OK) < 0) {
+               if (test_access(dir, X_OK, errmsg) < 0) {
                        if (errno == EACCES)
                                str_printfa(errmsg, " missing +x perm: %s", dir);
-                       else
-                               str_printfa(errmsg, " access(%s, x) failed: %m", dir);
-               } else if (creating && access(dir, W_OK) < 0) {
+               } else if (creating && test_access(dir, W_OK, errmsg) < 0) {
                        if (errno == EACCES)
                                str_printfa(errmsg, " missing +w perm: %s", dir);
-                       else
-                               str_printfa(errmsg, " access(%s, w) failed: %m", dir);
-               } else if (prev_path == path && access(path, R_OK) < 0) {
+               } else if (prev_path == path &&
+                          test_access(path, R_OK, errmsg) < 0) {
                        if (errno == EACCES)
                                str_printfa(errmsg, " missing +r perm: %s", path);
-                       else
-                               str_printfa(errmsg, " access(%s, r) failed: %m", path);
                } else
                        str_printfa(errmsg, " UNIX perms seem ok, ACL problem?");
        }