File 0007-chkstat-fix-privesc-CVE-2019-3690.patch of Package permissions

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File 0007-chkstat-fix-privesc-CVE-2019-3690.patch of Package permissions (Revision 48c60a331ca320acd5713adaaa13a905)

Currently displaying revision 48c60a331ca320acd5713adaaa13a905 , Show latest

Index: chkstat.c
===================================================================
--- chkstat.c.orig
+++ chkstat.c
@@ -18,6 +18,7 @@
  ****************************************************************
  */
 
+#define _GNU_SOURCE
 #include <stdio.h>
 #include <pwd.h>
 #include <grp.h>
@@ -29,11 +30,11 @@
 #include <errno.h>
 #include <dirent.h>
 #include <sys/capability.h>
-#define __USE_GNU
 #include <fcntl.h>
+#include <stdbool.h>
 
 #define BAD_LINE() \
-  fprintf(stderr, "bad permissions line %s:%d\n", permfiles[i], lcnt);
+  fprintf(stderr, "bad permissions line %s:%d\n", permfiles[i], lcnt)
 
 struct perm {
   struct perm *next;
@@ -46,17 +47,17 @@ struct perm {
 
 struct perm *permlist;
 char **checklist;
-int nchecklist;
+size_t nchecklist;
 uid_t euid;
 char *root;
-int rootl;
-int nlevel;
+size_t rootl;
+size_t nlevel;
 char** level;
 int do_set = -1;
 int default_set = 1;
 int have_fscaps = -1;
 char** permfiles = NULL;
-int npermfiles = 0;
+size_t npermfiles = 0;
 char* force_level;
 
 struct perm*
@@ -71,12 +72,12 @@ add_permlist(char *file, char *owner, ch
       char *nfile;
       nfile = malloc(strlen(file) + rootl + (*file != '/' ? 2 : 1));
       if (nfile)
-	{
-	  strcpy(nfile, root);
-	  if (*file != '/')
-	    strcat(nfile, "/");
-	  strcat(nfile, file);
-	}
+        {
+          strcpy(nfile, root);
+          if (*file != '/')
+            strcat(nfile, "/");
+          strcat(nfile, file);
+        }
       file = nfile;
     }
   else
@@ -116,7 +117,7 @@ add_permlist(char *file, char *owner, ch
 int
 in_checklist(char *e)
 {
-  int i;
+  size_t i;
   for (i = 0; i < nchecklist; i++)
     if (!strcmp(e, checklist[i]))
       return 1;
@@ -137,23 +138,23 @@ add_checklist(char *e)
   if ((nchecklist & 63) == 0)
     {
       if (checklist == 0)
-	checklist = malloc(sizeof(char *) * (nchecklist + 64));
+        checklist = malloc(sizeof(char *) * (nchecklist + 64));
       else
-	checklist = realloc(checklist, sizeof(char *) * (nchecklist + 64));
+        checklist = realloc(checklist, sizeof(char *) * (nchecklist + 64));
       if (checklist == 0)
-	{
-	  perror("checklist alloc");
-	  exit(1);
-	}
+        {
+          perror("checklist alloc");
+          exit(1);
+        }
     }
   checklist[nchecklist++] = e;
 }
 
 int
-readline(FILE *fp, char *buf, int len)
+readline(FILE *fp, char *buf, size_t len)
 {
-  int l;
-  if (!fgets(buf, len, fp))
+  size_t l;
+  if (!fgets(buf, (int)len, fp))
     return 0;
   l = strlen(buf);
   if (l && buf[l - 1] == '\n')
@@ -164,7 +165,8 @@ readline(FILE *fp, char *buf, int len)
   if (l + 1 < len)
     return 1;
   fprintf(stderr, "warning: buffer overrun in line starting with '%s'\n", buf);
-  while ((l = getc(fp)) != EOF && l != '\n')
+  char c;
+  while ((c = getc(fp)) != EOF && c != '\n')
     ;
   buf[0] = 0;
   return 1;
@@ -173,7 +175,7 @@ readline(FILE *fp, char *buf, int len)
 int
 in_level(char *e)
 {
-  int i;
+  size_t i;
   for (i = 0; i < nlevel; i++)
     if (!strcmp(e, level[i]))
       return 1;
@@ -181,19 +183,19 @@ in_level(char *e)
 }
 
 void
-ensure_array(void** array, int* size)
+ensure_array(void** array, size_t* size)
 {
   if ((*size & 63) == 0)
     {
       if (*array == NULL)
-	*array = malloc(sizeof(char *) * (*size + 64));
+        *array = malloc(sizeof(char *) * (*size + 64));
       else
-	*array = realloc(*array, sizeof(char *) * (*size + 64));
+        *array = realloc(*array, sizeof(char *) * (*size + 64));
       if (*array == NULL)
-	{
-	  perror("array alloc");
-	  exit(1);
-	}
+        {
+          perror("array alloc");
+          exit(1);
+        }
     }
 }
 
@@ -221,7 +223,7 @@ int
 parse_sysconf(const char* file)
 {
   FILE* fp;
-  char line[1024];
+  char line[PATH_MAX];
   char* p;
   if ((fp = fopen(file, "r")) == 0)
     {
@@ -231,77 +233,77 @@ parse_sysconf(const char* file)
   while (readline(fp, line, sizeof(line)))
     {
       if (!*line)
-	continue;
+        continue;
       for (p = line; *p == ' '; ++p);
       if (!*p || *p == '#')
-	continue;
+        continue;
       if (!strncmp(p, "PERMISSION_SECURITY=", 20))
-	{
-	  if (force_level)
-	    continue;
-
-	  p+=20;
-	  if (isquote(*p))
-	    ++p;
-	  p = strtok(p, " ");
-	  if (p && !isquote(*p))
-	    {
-	      do
-		{
-		  if (isquote(p[strlen(p)-1]))
-		    {
-		      p[strlen(p)-1] = '\0';
-		    }
-		  if (*p && strcmp(p, "local"))
-		      add_level(p);
-		}
-	      while ((p = strtok(NULL, " ")));
-	    }
-	}
+        {
+          if (force_level)
+            continue;
+
+          p+=20;
+          if (isquote(*p))
+            ++p;
+          p = strtok(p, " ");
+          if (p && !isquote(*p))
+            {
+              do
+                {
+                  if (isquote(p[strlen(p)-1]))
+                    {
+                      p[strlen(p)-1] = '\0';
+                    }
+                  if (*p && strcmp(p, "local"))
+                      add_level(p);
+                }
+              while ((p = strtok(NULL, " ")));
+            }
+        }
       else if (!strncmp(p, "CHECK_PERMISSIONS=", 18))
-	{
-	  p+=18;
-	  if (isquote(*p))
-	    ++p;
-	  if (!strncmp(p, "set", 3))
-	    {
-	      p+=3;
-	      if (isquote(*p) || !*p)
-		default_set=1;
-	    }
-	  else if ((!strncmp(p, "no", 2) && (!p[3] || isquote(p[3]))) || !*p || isquote(*p))
-	    {
-	      p+=2;
-	      if (isquote(*p) || !*p)
-		{
-		  default_set = -1;
-		}
-	    }
-	  else
-	    {
-	      //fprintf(stderr, "invalid value for CHECK_PERMISSIONS (must be 'set', 'warn' or 'no')\n");
-	    }
-	}
+        {
+          p+=18;
+          if (isquote(*p))
+            ++p;
+          if (!strncmp(p, "set", 3))
+            {
+              p+=3;
+              if (isquote(*p) || !*p)
+                default_set=1;
+            }
+          else if ((!strncmp(p, "no", 2) && (!p[3] || isquote(p[3]))) || !*p || isquote(*p))
+            {
+              p+=2;
+              if (isquote(*p) || !*p)
+                {
+                  default_set = -1;
+                }
+            }
+          else
+            {
+              //fprintf(stderr, "invalid value for CHECK_PERMISSIONS (must be 'set', 'warn' or 'no')\n");
+            }
+        }
 #define FSCAPSENABLE "PERMISSION_FSCAPS="
       else if (have_fscaps == -1 && !strncmp(p, FSCAPSENABLE, strlen(FSCAPSENABLE)))
-	{
-	  p+=strlen(FSCAPSENABLE);
-	  if (isquote(*p))
-	    ++p;
-	  if (!strncmp(p, "yes", 3))
-	    {
-	      p+=3;
-	      if (isquote(*p) || !*p)
-		have_fscaps=1;
-	    }
-	  else if (!strncmp(p, "no", 2))
-	    {
-	      p+=2;
-	      if (isquote(*p) || !*p)
-		have_fscaps=0;
-	    } else
-	        have_fscaps=1; /* default */
-	}
+        {
+          p+=strlen(FSCAPSENABLE);
+          if (isquote(*p))
+            ++p;
+          if (!strncmp(p, "yes", 3))
+            {
+              p+=3;
+              if (isquote(*p) || !*p)
+                have_fscaps=1;
+            }
+          else if (!strncmp(p, "no", 2))
+            {
+              p+=2;
+              if (isquote(*p) || !*p)
+                have_fscaps=0;
+            } else
+                have_fscaps=1; /* default */
+        }
     }
   fclose(fp);
   return 0;
@@ -316,7 +318,7 @@ compare(const void* a, const void* b)
 static void
 collect_permfiles()
 {
-  int i;
+  size_t i;
   DIR* dir;
 
   ensure_array((void**)&permfiles, &npermfiles);
@@ -327,76 +329,81 @@ collect_permfiles()
   for (i = 0; i < nlevel; ++i)
     {
       if (!strcmp(level[i], "easy")
-	      || !strcmp(level[i], "secure")
-	      || !strcmp(level[i], "paranoid"))
-	{
-	  char fn[4096];
-	  snprintf(fn, sizeof(fn), "/etc/permissions.%s", level[i]);
-	  if (access(fn, R_OK) == 0)
-	    {
-	      ensure_array((void**)&permfiles, &npermfiles);
-	      permfiles[npermfiles++] = strdup(fn);
-	    }
-	}
+              || !strcmp(level[i], "secure")
+              || !strcmp(level[i], "paranoid"))
+        {
+          char fn[4096];
+          snprintf(fn, sizeof(fn), "/etc/permissions.%s", level[i]);
+          if (access(fn, R_OK) == 0)
+            {
+              ensure_array((void**)&permfiles, &npermfiles);
+              permfiles[npermfiles++] = strdup(fn);
+            }
+        }
     }
   // 3. package specific permissions
   dir = opendir("/etc/permissions.d");
   if (dir)
     {
       char** files = NULL;
-      int nfiles = 0;
+      size_t nfiles = 0;
       struct dirent* d;
       while ((d = readdir(dir)))
-	{
-	  char* p;
-	  if (!strcmp("..", d->d_name) || !strcmp(".", d->d_name))
-	    continue;
-
-	  /* filter out backup files */
-	  if ((strlen(d->d_name)>2) && (d->d_name[strlen(d->d_name)-1] == '~'))
-	    continue;
-	  if (strstr(d->d_name,".rpmnew") || strstr(d->d_name,".rpmsave"))
-	    continue;
-
-	  ensure_array((void**)&files, &nfiles);
-	  if ((p = strchr(d->d_name, '.')))
-	    {
-	      *p = '\0';
-	    }
-	  files[nfiles++] = strdup(d->d_name);
-	}
+        {
+          char* p;
+          if (!strcmp("..", d->d_name) || !strcmp(".", d->d_name))
+            continue;
+
+          /* filter out backup files */
+          if ((strlen(d->d_name)>2) && (d->d_name[strlen(d->d_name)-1] == '~'))
+            continue;
+          if (strstr(d->d_name,".rpmnew") || strstr(d->d_name,".rpmsave"))
+            continue;
+
+          ensure_array((void**)&files, &nfiles);
+          if ((p = strchr(d->d_name, '.')))
+            {
+              *p = '\0';
+            }
+          files[nfiles++] = strdup(d->d_name);
+        }
       closedir(dir);
       if (nfiles)
-	{
-	  qsort(files, nfiles, sizeof(char*), compare);
-	  for (i = 0; i < nfiles; ++i)
-	    {
-	      char fn[4096];
-	      int l;
-	      // skip duplicates
-	      if (i && !strcmp(files[i-1], files[i]))
-		continue;
-
-	      snprintf(fn, sizeof(fn), "/etc/permissions.d/%s", files[i]);
-	      if (access(fn, R_OK) == 0)
-		{
-		  ensure_array((void**)&permfiles, &npermfiles);
-		  permfiles[npermfiles++] = strdup(fn);
-		}
-
-	      for (l = 0; l < nlevel; ++l)
-		{
-		  snprintf(fn, sizeof(fn), "/etc/permissions.d/%s.%s", files[i], level[l]);
-
-		  if (access(fn, R_OK) == 0)
-		    {
-		      ensure_array((void**)&permfiles, &npermfiles);
-		      permfiles[npermfiles++] = strdup(fn);
-		    }
-		}
-
-	    }
-	}
+        {
+          qsort(files, nfiles, sizeof(char*), compare);
+          for (i = 0; i < nfiles; ++i)
+            {
+              char fn[4096];
+              size_t l;
+              // skip duplicates
+              if (i && !strcmp(files[i-1], files[i]))
+                continue;
+
+              snprintf(fn, sizeof(fn), "/etc/permissions.d/%s", files[i]);
+              if (access(fn, R_OK) == 0)
+                {
+                  ensure_array((void**)&permfiles, &npermfiles);
+                  permfiles[npermfiles++] = strdup(fn);
+                }
+
+              for (l = 0; l < nlevel; ++l)
+                {
+                  snprintf(fn, sizeof(fn), "/etc/permissions.d/%s.%s", files[i], level[l]);
+
+                  if (access(fn, R_OK) == 0)
+                    {
+                      ensure_array((void**)&permfiles, &npermfiles);
+                      permfiles[npermfiles++] = strdup(fn);
+                    }
+                }
+
+            }
+          for (i = 0; i < nfiles; ++i)
+            {
+              free(files[i]);
+            }
+        }
+      free(files);
     }
   // 4. central permissions files with user defined level incl 'local'
   for (i = 0; i < nlevel; ++i)
@@ -404,14 +411,14 @@ collect_permfiles()
       char fn[4096];
 
       if (!strcmp(level[i], "easy") || !strcmp(level[i], "secure") || !strcmp(level[i], "paranoid"))
-	continue;
+        continue;
 
       snprintf(fn, sizeof(fn), "/etc/permissions.%s", level[i]);
       if (access(fn, R_OK) == 0)
-	{
-	  ensure_array((void**)&permfiles, &npermfiles);
-	  permfiles[npermfiles++] = strdup(fn);
-	}
+        {
+          ensure_array((void**)&permfiles, &npermfiles);
+          permfiles[npermfiles++] = strdup(fn);
+        }
     }
 }
 
@@ -424,117 +431,158 @@ usage(int x)
 "b) chkstat --system [OPTIONS] <files>...\n"
 "\n"
 "Options:\n"
-"  --set			apply changes\n"
-"  --warn		only tell which changes are needed\n"
-"  --noheader		don't print intro message\n"
-"  --fscaps		force use of fscaps\n"
-"  --no-fscaps		disable use of fscaps\n"
-"  --system		system mode, act according to /etc/permissions/security\n"
-"  --level LEVEL		force use LEVEL (only with --system)\n"
-"  --examine FILE	apply to specified file only\n"
-"  --files FILELIST	read list of files to apply from FILELIST\n"
-"  --root DIR		check files relative to DIR\n"
+"  --set                        apply changes\n"
+"  --warn                only tell which changes are needed\n"
+"  --noheader                don't print intro message\n"
+"  --fscaps                force use of fscaps\n"
+"  --no-fscaps                disable use of fscaps\n"
+"  --system                system mode, act according to /etc/permissions/security\n"
+"  --level LEVEL                force use LEVEL (only with --system)\n"
+"  --examine FILE        apply to specified file only\n"
+"  --files FILELIST        read list of files to apply from FILELIST\n"
+"  --root DIR                check files relative to DIR\n"
 );
   exit(x);
 }
 
 int
-safepath(char *path, uid_t uid, gid_t gid)
+safe_open(char *path, struct stat *stb, uid_t target_uid, bool *traversed_insecure)
 {
-  struct stat stb;
-  char pathbuf[1024];
-  char linkbuf[1024];
-  char *p, *p2;
-  int l, l2, lcnt;
+  char pathbuf[PATH_MAX];
+  char *p;
+  int lcnt;
+  int pathfd = -1;
+  struct stat root_st;
+
+  *traversed_insecure = false;
 
   lcnt = 0;
-  l2 = strlen(path);
-  if ((unsigned)l2 >= sizeof(pathbuf))
-    return 0;
-  strcpy(pathbuf, path);
-  if (pathbuf[0] != '/') 
-    return 0;
-  p = pathbuf + rootl;
-  for (;;)
+  if ((size_t)snprintf(pathbuf, sizeof(pathbuf), "%s", path + rootl) >= sizeof(pathbuf))
+    goto fail;
+  p = pathbuf;
+  do
     {
-      p = strchr(p, '/');
-      if (!p)
-        return 1;
-      *p = 0;
-      if (lstat(*pathbuf ? pathbuf : "/", &stb))
-	return 0;
-      if (S_ISLNK(stb.st_mode))
-	{
-	  if (++lcnt >= 256)
-	    return 0;
-	  l = readlink(pathbuf, linkbuf, sizeof(linkbuf));
-	  if (l <= 0 || (unsigned)l >= sizeof(linkbuf))
-	    return 0;
-	  while(l && linkbuf[l - 1] == '/')
-	    l--;
-	  if ((unsigned)l + 1 >= sizeof(linkbuf))
-	    return 0;
-	  linkbuf[l++] = '/';
-	  linkbuf[l] = 0;
-	  *p++ = '/';
-	  if (linkbuf[0] == '/')
-	    {
-	      if (rootl)
-		{
-		  p[-1] = 0;
-		  fprintf(stderr, "can't handle symlink %s at the moment\n", pathbuf);
-		  return 0;
-		}
-	      l2 -= (p - pathbuf);
-	      memmove(pathbuf + rootl, p, l2 + 1);
-	      l2 += rootl;
-	      p = pathbuf + rootl;
-	    }
-	  else
-	    {
-	      if (p - 1 == pathbuf)
-		return 0;		/* huh, "/" is a symlink */
-	      for (p2 = p - 2; p2 >= pathbuf; p2--)
-		if (*p2 == '/')
-		  break;
-	      if (p2 < pathbuf + rootl)	/* cannot happen */
-		return 0;
-	      p2++;			/* am now after '/' */
-              memmove(p2, p, pathbuf + l2 - p + 1);
-	      l2 -= (p - p2);
-	      p = p2;
-	    }
-	  if ((unsigned)(l + l2) >= sizeof(pathbuf))
-	    return 0;
-	  memmove(p + l, p, pathbuf + l2 - p + 1);
-	  memmove(p, linkbuf, l);
-	  l2 += l;
-	  if (pathbuf[0] != '/')	/* cannot happen */
-	    return 0;
-	  if (p == pathbuf)
-	    p++;
-	  continue;
-	}
-      if (!S_ISDIR(stb.st_mode))
-	return 0;
-
-      /* write is always forbidden for other */
-      if ((stb.st_mode & 02) != 0)
-	return 0;
+      *p = '/';
+      char *cursor = p + 1;
+
+      if (pathfd == -1)
+        {
+          pathfd = open(rootl ? root : "/", O_PATH | O_CLOEXEC);
+          if (pathfd == -1)
+            {
+              fprintf(stderr, "failed to open root directory %s: %s\n", root, strerror(errno));
+              goto fail;
+            }
+          if (fstat(pathfd, &root_st))
+            {
+              fprintf(stderr, "failed to stat root directory %s: %s\n", root, strerror(errno));
+              goto fail;
+            }
+          // stb and pathfd must be in sync for the root-escape check below
+          memcpy(stb, &root_st, sizeof(*stb));
+        }
+
+      p = strchr(cursor, '/');
+      // p is NULL when we reach the final path element
+      if (p)
+        *p = 0;
+
+      // multiple consecutive slashes: ignore
+      if (p && *cursor == '\0')
+        continue;
+
+      // never move up from the configured root directory (using the stat result from the previous loop iteration)
+      if (strcmp(cursor, "..") == 0 && rootl && stb->st_dev == root_st.st_dev && stb->st_ino == root_st.st_ino)
+          continue;
+
+      // cursor is an empty string for trailing slashes, open again with different open_flags.
+      int newpathfd = openat(pathfd, *cursor ? cursor : ".", O_PATH | O_NOFOLLOW | O_CLOEXEC | O_NONBLOCK);
+      if (newpathfd == -1)
+        goto fail;
+
+      close(pathfd);
+      pathfd = newpathfd;
+
+      if (fstat(pathfd, stb))
+        goto fail;
 
-      /* owner must be ok as she may change the mode */
+      /* owner of directories must be trusted for setuid/setgid/capabilities as we have no way to verify file contents */
       /* for euid != 0 it is also ok if the owner is euid */
-      if (stb.st_uid && stb.st_uid != uid && stb.st_uid != euid)
-	return 0;
+      if (stb->st_uid && stb->st_uid != euid && p)
+        *traversed_insecure = true;
+      // path is in a world-writable directory, or file is world-writable itself.
+      if (!S_ISLNK(stb->st_mode) && (stb->st_mode & S_IWOTH) && p)
+        *traversed_insecure = true;
+      // if parent directory is not owned by root, the file owner must match the owner of parent
+      if (stb->st_uid && stb->st_uid != target_uid && stb->st_uid != euid)
+        {
+          if (p)
+            goto fail_insecure_path;
+          // do not backport this behavior change
+          //else
+          //  fprintf(stderr, "%s: has unexpected owner. refusing to correct due to unknown integrity.\n", path+rootl);
+          //goto fail;
+        }
 
-      /* group gid may do fancy things */
-      /* for euid != 0 we don't check this */
-      if ((stb.st_mode & 020) != 0 && !euid)
-	if (!gid || stb.st_gid != gid)
-	  return 0;
+      if (S_ISLNK(stb->st_mode))
+        {
+          // Don't follow symlinks owned by regular users.
+          // In theory, we could also trust symlinks where the owner of the target matches the owner
+          // of the link, but we're going the simple route for now.
+          if (stb->st_uid && stb->st_uid != euid)
+            goto fail_insecure_path;
+
+          if (++lcnt >= 256)
+            goto fail;
+          char linkbuf[PATH_MAX];
+          ssize_t l = readlinkat(pathfd, "", linkbuf, sizeof(linkbuf) - 1);
+          if (l <= 0 || (size_t)l >= sizeof(linkbuf) - 1)
+            goto fail;
+          while(l && linkbuf[l - 1] == '/')
+            l--;
+          linkbuf[l] = 0;
+          if (linkbuf[0] == '/')
+            {
+              // absolute link
+              close(pathfd);
+              pathfd = -1;
+            }
+          size_t len;
+          char tmp[sizeof(pathbuf)]; // need a temporary buffer because p points into pathbuf and snprintf doesn't allow the same buffer as source and destination
+          if (p)
+            len = (size_t)snprintf(tmp, sizeof(tmp), "%s/%s", linkbuf, p + 1);
+          else
+            len = (size_t)snprintf(tmp, sizeof(tmp), "%s", linkbuf);
+          if (len >= sizeof(pathbuf))
+            goto fail;
+          strcpy(pathbuf, tmp);
+          p = pathbuf;
+        }
+    } while (p);
 
-      *p++ = '/';
-    }
+  // world-writable file: error out due to unknown file integrity
+  if (S_ISREG(stb->st_mode) && (stb->st_mode & S_IWOTH)) {
+    fprintf(stderr, "%s: file has insecure permissions (world-writable)\n", path+rootl);
+    goto fail;
+  }
+
+  return pathfd;
+fail_insecure_path:
+
+  {
+    char linkpath[PATH_MAX];
+    char procpath[100];
+    snprintf(procpath, sizeof(procpath), "/proc/self/fd/%d", pathfd);
+    ssize_t l = readlink(procpath, linkpath, sizeof(linkpath) - 1);
+    if (l > 0 && (size_t)l < sizeof(linkpath) - 1)
+      linkpath[l] = '\0';
+      fprintf(stderr, "%s: on an insecure path - %s has different non-root owner who could tamper with the file.\n", path+rootl, linkpath);
+  }
+
+fail:
+  if (pathfd >= 0)
+    close(pathfd);
+  return -1;
 }
 
 /* check /sys/kernel/fscaps, 2.6.39 */
@@ -560,7 +608,7 @@ out:
 int
 main(int argc, char **argv)
 {
-  char *opt, *p, *str;
+  char *opt, *str;
   int told = 0;
   int use_checklist = 0;
   int systemmode = 0;
@@ -568,16 +616,17 @@ main(int argc, char **argv)
   FILE *fp;
   char line[512];
   char *part[4];
-  int i, pcnt, lcnt;
+  int pcnt, lcnt;
+  size_t i;
   int inpart;
   mode_t mode;
   struct perm *e;
-  struct stat stb, stb2;
+  struct stat stb;
   struct passwd *pwd = 0;
   struct group *grp = 0;
   uid_t uid;
   gid_t gid;
-  int fd, r;
+  int fd = -1;
   int errors = 0;
   cap_t caps = NULL;
 
@@ -585,137 +634,137 @@ main(int argc, char **argv)
     {
       opt = argv[1];
       if (!strcmp(opt, "--"))
-	break;
+        break;
       if (*opt == '-' && opt[1] == '-')
-	opt++;
+        opt++;
       if (!strcmp(opt, "-system"))
-	{
-	  argc--;
-	  argv++;
-	  systemmode = 1;
-	  continue;
-	}
+        {
+          argc--;
+          argv++;
+          systemmode = 1;
+          continue;
+        }
       // hidden option for use by suseconfig only
       if (!strcmp(opt, "-suseconfig"))
-	{
-	  argc--;
-	  argv++;
-	  suseconfig = 1;
-	  systemmode = 1;
-	  continue;
-	}
+        {
+          argc--;
+          argv++;
+          suseconfig = 1;
+          systemmode = 1;
+          continue;
+        }
       if (!strcmp(opt, "-fscaps"))
-	{
-	  argc--;
-	  argv++;
-	  have_fscaps = 1;
-	  continue;
-	}
+        {
+          argc--;
+          argv++;
+          have_fscaps = 1;
+          continue;
+        }
       if (!strcmp(opt, "-no-fscaps"))
-	{
-	  argc--;
-	  argv++;
-	  have_fscaps = 0;
-	  continue;
-	}
+        {
+          argc--;
+          argv++;
+          have_fscaps = 0;
+          continue;
+        }
       if (!strcmp(opt, "-s") || !strcmp(opt, "-set"))
-	{
-	  do_set=1;
-	  argc--;
-	  argv++;
-	  continue;
-	}
+        {
+          do_set=1;
+          argc--;
+          argv++;
+          continue;
+        }
       if (!strcmp(opt, "-warn"))
-	{
-	  do_set=0;
-	  argc--;
-	  argv++;
-	  continue;
-	}
+        {
+          do_set=0;
+          argc--;
+          argv++;
+          continue;
+        }
       if (!strcmp(opt, "-n") || !strcmp(opt, "-noheader"))
-	{
-	  told = 1;
-	  argc--;
-	  argv++;
-	  continue;
-	}
+        {
+          told = 1;
+          argc--;
+          argv++;
+          continue;
+        }
       if (!strcmp(opt, "-e") || !strcmp(opt, "-examine"))
-	{
-	  argc--;
-	  argv++;
-	  if (argc == 1)
-	    {
-	      fprintf(stderr, "examine: argument required\n");
-	      exit(1);
-	    }
-	  add_checklist(argv[1]);
-	  use_checklist = 1;
-	  argc--;
-	  argv++;
-	  continue;
-	}
+        {
+          argc--;
+          argv++;
+          if (argc == 1)
+            {
+              fprintf(stderr, "examine: argument required\n");
+              exit(1);
+            }
+          add_checklist(argv[1]);
+          use_checklist = 1;
+          argc--;
+          argv++;
+          continue;
+        }
       if (!strcmp(opt, "-level"))
-	{
-	  argc--;
-	  argv++;
-	  if (argc == 1)
-	    {
-	      fprintf(stderr, "level: argument required\n");
-	      exit(1);
-	    }
-	  force_level = argv[1];
-	  argc--;
-	  argv++;
-	  continue;
-	}
+        {
+          argc--;
+          argv++;
+          if (argc == 1)
+            {
+              fprintf(stderr, "level: argument required\n");
+              exit(1);
+            }
+          force_level = argv[1];
+          argc--;
+          argv++;
+          continue;
+        }
       if (!strcmp(opt, "-f") || !strcmp(opt, "-files"))
-	{
-	  argc--;
-	  argv++;
-	  if (argc == 1)
-	    {
-	      fprintf(stderr, "files: argument required\n");
-	      exit(1);
-	    }
-	  if ((fp = fopen(argv[1], "r")) == 0)
-	    {
-	      fprintf(stderr, "files: %s: %s\n", argv[1], strerror(errno));
-	      exit(1);
-	    }
-	  while (readline(fp, line, sizeof(line)))
-	    {
-	      if (!*line)
-		continue;
-	      add_checklist(line);
-	    }
-	  fclose(fp);
-	  use_checklist = 1;
-	  argc--;
-	  argv++;
-	  continue;
-	}
+        {
+          argc--;
+          argv++;
+          if (argc == 1)
+            {
+              fprintf(stderr, "files: argument required\n");
+              exit(1);
+            }
+          if ((fp = fopen(argv[1], "r")) == 0)
+            {
+              fprintf(stderr, "files: %s: %s\n", argv[1], strerror(errno));
+              exit(1);
+            }
+          while (readline(fp, line, sizeof(line)))
+            {
+              if (!*line)
+                continue;
+              add_checklist(line);
+            }
+          fclose(fp);
+          use_checklist = 1;
+          argc--;
+          argv++;
+          continue;
+        }
       if (!strcmp(opt, "-r") || !strcmp(opt, "-root"))
-	{
-	  argc--;
-	  argv++;
-	  if (argc == 1)
-	    {
-	      fprintf(stderr, "root: argument required\n");
-	      exit(1);
-	    }
-	  root = argv[1];
-	  rootl = strlen(root);
-	  if (*root != '/')
-	    {
-	      fprintf(stderr, "root: must begin with '/'\n");
-	      exit(1);
-	    }
-	  argc--;
-	  argv++;
-	  continue;
-	}
+        {
+          argc--;
+          argv++;
+          if (argc == 1)
+            {
+              fprintf(stderr, "root: argument required\n");
+              exit(1);
+            }
+          root = argv[1];
+          rootl = strlen(root);
+          if (*root != '/')
+            {
+              fprintf(stderr, "root: must begin with '/'\n");
+              exit(1);
+            }
+          argc--;
+          argv++;
+          continue;
+        }
       if (*opt == '-')
-	usage(!strcmp(opt, "-h") || !strcmp(opt, "-help") ? 0 : 1);
+        usage(!strcmp(opt, "-h") || !strcmp(opt, "-help") ? 0 : 1);
       break;
     }
 
@@ -724,50 +773,50 @@ main(int argc, char **argv)
       const char file[] = "/etc/sysconfig/security";
       parse_sysconf(file);
       if(do_set == -1)
-	{
-	  if (default_set < 0)
-	    {
-	      fprintf(stderr, "permissions handling disabled in %s\n", file);
-	      exit(0);
-	    }
-	  if (suseconfig && default_set)
-	    {
-	      char* module = getenv("ONLY_MODULE");
-	      if (!module || strcmp(module, "permissions"))
-		{
-		  puts("no permissions will be changed if not called explicitly");
-		  default_set = 0;
-		}
-	    }
-	  do_set = default_set;
-	}
+        {
+          if (default_set < 0)
+            {
+              fprintf(stderr, "permissions handling disabled in %s\n", file);
+              exit(0);
+            }
+          if (suseconfig && default_set)
+            {
+              char* module = getenv("ONLY_MODULE");
+              if (!module || strcmp(module, "permissions"))
+                {
+                  puts("no permissions will be changed if not called explicitly");
+                  default_set = 0;
+                }
+            }
+          do_set = default_set;
+        }
       if (force_level)
-	{
-	  char *p = strtok(force_level, " ");
-	  do
-	    {
-	      add_level(p);
-	    }
-	  while ((p = strtok(NULL, " ")));
-	}
+        {
+          char *p = strtok(force_level, " ");
+          do
+            {
+              add_level(p);
+            }
+          while ((p = strtok(NULL, " ")));
+        }
 
       if (!nlevel)
-	add_level("secure");
+        add_level("secure");
       add_level("local"); // always add local
 
-      for (i = 1; i < argc; i++)
-	{
-	  add_checklist(argv[i]);
-	  use_checklist = 1;
-	  continue;
-	}
+      for (i = 1; i < (size_t)argc; i++)
+        {
+          add_checklist(argv[i]);
+          use_checklist = 1;
+          continue;
+        }
       collect_permfiles();
     }
   else if (argc <= 1)
     usage(1);
   else
     {
-      npermfiles = argc-1;
+      npermfiles = (size_t)argc-1;
       permfiles = &argv[1];
     }
 
@@ -786,94 +835,95 @@ main(int argc, char **argv)
   for (i = 0; i < npermfiles; i++)
     {
       if ((fp = fopen(permfiles[i], "r")) == 0)
-	{
-	  perror(permfiles[i]);
-	  exit(1);
-	}
+        {
+          perror(permfiles[i]);
+          exit(1);
+        }
       lcnt = 0;
       struct perm* last = NULL;
       int extline;
       while (readline(fp, line, sizeof(line)))
-	{
-	  extline = 0;
-	  lcnt++;
-	  if (*line == 0 || *line == '#' || *line == '$')
-	    continue;
-	  inpart = 0;
-	  pcnt = 0;
-	  for (p = line; *p; p++)
-	    {
-	      if (*p == ' ' || *p == '\t')
-		{
-		  *p = 0;
-		  if (inpart)
-		    {
-		      pcnt++;
-		      inpart = 0;
-		    }
-		  continue;
-		}
-	      if (pcnt == 0 && !inpart && *p == '+')
-		{
-		  extline = 1;
-		  break;
-		}
-	      if (!inpart)
-		{
-		  inpart = 1;
-		  if (pcnt == 3)
-		    break;
-		  part[pcnt] = p;
-		}
-	    }
-	  if (extline)
-	    {
-	      if (!last)
-		{
-		  BAD_LINE();
-		  continue;
-		}
-	      if (!strncmp(p, "+capabilities ", 14))
-		{
-		  if (have_fscaps != 1)
-		    continue;
-		  p += 14;
-		  caps = cap_from_text(p);
-		  if (caps)
-		    {
-		      cap_free(last->caps);
-		      last->caps = caps;
-		    }
-		  continue;
-		}
-	      BAD_LINE();
-	      continue;
-	    }
-	  if (inpart)
-	    pcnt++;
-	  if (pcnt != 3)
-	    {
-	      BAD_LINE();
-	      continue;
-	    }
-	  part[3] = part[2];
-	  part[2] = strchr(part[1], ':');
-	  if (!part[2])
-	    part[2] = strchr(part[1], '.');
-	  if (!part[2])
-	    {
-	      BAD_LINE();
-	      continue;
-	    }
-	  *part[2]++ = 0;
-          mode = strtoul(part[3], part + 3, 8);
-	  if (mode > 07777 || part[3][0])
-	    {
-	      BAD_LINE();
-	      continue;
-	    }
-	  last = add_permlist(part[0], part[1], part[2], mode);
-	}
+        {
+          extline = 0;
+          lcnt++;
+          if (*line == 0 || *line == '#' || *line == '$')
+            continue;
+          inpart = 0;
+          pcnt = 0;
+          char *p;
+          for (p = line; *p; p++)
+            {
+              if (*p == ' ' || *p == '\t')
+                {
+                  *p = 0;
+                  if (inpart)
+                    {
+                      pcnt++;
+                      inpart = 0;
+                    }
+                  continue;
+                }
+              if (pcnt == 0 && !inpart && *p == '+')
+                {
+                  extline = 1;
+                  break;
+                }
+              if (!inpart)
+                {
+                  inpart = 1;
+                  if (pcnt == 3)
+                    break;
+                  part[pcnt] = p;
+                }
+            }
+          if (extline)
+            {
+              if (!last)
+                {
+                  BAD_LINE();
+                  continue;
+                }
+              if (!strncmp(p, "+capabilities ", 14))
+                {
+                  if (have_fscaps != 1)
+                    continue;
+                  p += 14;
+                  caps = cap_from_text(p);
+                  if (caps)
+                    {
+                      cap_free(last->caps);
+                      last->caps = caps;
+                    }
+                  continue;
+                }
+              BAD_LINE();
+              continue;
+            }
+          if (inpart)
+            pcnt++;
+          if (pcnt != 3)
+            {
+              BAD_LINE();
+              continue;
+            }
+          part[3] = part[2];
+          part[2] = strchr(part[1], ':');
+          if (!part[2])
+            part[2] = strchr(part[1], '.');
+          if (!part[2])
+            {
+              BAD_LINE();
+              continue;
+            }
+          *part[2]++ = 0;
+          mode = (mode_t)strtoul(part[3], part + 3, 8);
+          if (mode > 07777 || part[3][0])
+            {
+              BAD_LINE();
+              continue;
+            }
+          last = add_permlist(part[0], part[1], part[2], mode);
+        }
       fclose(fp);
     }
 
@@ -881,243 +931,244 @@ main(int argc, char **argv)
   for (e = permlist; e; e = e->next)
     {
       if (use_checklist && !in_checklist(e->file+rootl))
-	continue;
-      if (lstat(e->file, &stb))
-	continue;
+        continue;
+
+      pwd = strcmp(e->owner, "unknown") ? getpwnam(e->owner) : NULL;
+      grp = strcmp(e->group, "unknown") ? getgrnam(e->group) : NULL;
+      uid = pwd ? pwd->pw_uid : 0;
+      gid = grp ? grp->gr_gid : 0;
+
+      bool traversed_insecure;
+      if (fd >= 0)
+        {
+          // close fd from previous loop iteration
+          close(fd);
+          fd = -1;
+        }
+
+      fd = safe_open(e->file, &stb, uid, &traversed_insecure);
+      if (fd < 0)
+        continue;
       if (S_ISLNK(stb.st_mode))
-	continue;
+        continue;
+
       if (!e->mode && !strcmp(e->owner, "unknown"))
-	{
-	  char uids[16], gids[16];
-	  pwd = getpwuid(stb.st_uid);
-	  grp = getgrgid(stb.st_gid);
-	  if (!pwd)
-	    sprintf(uids, "%d", stb.st_uid);
-	  if (!grp)
-	    sprintf(gids, "%d", stb.st_gid);
-	  fprintf(stderr, "%s: cannot verify %s:%s %04o - not listed in /etc/permissions\n",
-		  e->file+rootl,
-		  pwd?pwd->pw_name:uids,
-		  grp?grp->gr_name:gids,
-		  (int)(stb.st_mode&07777));
-	  pwd = 0;
-	  grp = 0;
-	  continue;
-	}
-      if ((!pwd || strcmp(pwd->pw_name, e->owner)) && (pwd = getpwnam(e->owner)) == 0)
-	{
-	  fprintf(stderr, "%s: unknown user %s\n", e->file+rootl, e->owner);
-	  continue;
-	}
-      if ((!grp || strcmp(grp->gr_name, e->group)) && (grp = getgrnam(e->group)) == 0)
-	{
-	  fprintf(stderr, "%s: unknown group %s\n", e->file+rootl, e->group);
-	  continue;
-	}
-      uid = pwd->pw_uid;
-      gid = grp->gr_gid;
-      caps = cap_get_file(e->file);
+        {
+          fprintf(stderr, "%s: cannot verify ", e->file+rootl);
+          pwd = getpwuid(stb.st_uid);
+          if (pwd)
+            fprintf(stderr, "%s:", pwd->pw_name);
+          else
+            fprintf(stderr, "%d:", stb.st_uid);
+          grp = getgrgid(stb.st_gid);
+          if (grp)
+            fprintf(stderr, "%s", grp->gr_name);
+          else
+            fprintf(stderr, "%d", stb.st_gid);
+          fprintf(stderr, " %04o - not listed in /etc/permissions\n",
+                          (int)(stb.st_mode&07777));
+          continue;
+        }
+      if (!pwd)
+        {
+          fprintf(stderr, "%s: unknown user %s. ignoring entry.\n", e->file+rootl, e->owner);
+          continue;
+        }
+      else if (!grp)
+        {
+          fprintf(stderr, "%s: unknown group %s. ignoring entry.\n", e->file+rootl, e->group);
+          continue;
+        }
+
+      // fd is opened with O_PATH, file oeprations like cap_get_fd() and fchown() don't work with it.
+      //
+      // We also don't want to do a proper open() of the file, since that doesn't even work for sockets
+      // and might have side effects for pipes or devices.
+      //
+      // So we use path-based operations (yes!) with /proc/self/fd/xxx. (Since safe_open already resolved
+      // all symlinks, 'fd' can't refer to a symlink which we'd have to worry might get followed.)
+      char fd_path[100];
+      snprintf(fd_path, sizeof(fd_path), "/proc/self/fd/%d", fd);
+
+      caps = cap_get_file(fd_path);
       if (!caps)
-	{
-	  cap_free(caps);
-	  caps = NULL;
-	  if (errno == EOPNOTSUPP)
-	    {
-	      //fprintf(stderr, "%s: fscaps not supported\n", e->file+rootl);
-	      cap_free(e->caps);
-	      e->caps = NULL;
-	    }
-	}
+        {
+          // we get EBADF for files that don't support capabilities, e.g. sockets or FIFOs
+          if (errno == EBADF)
+            {
+              if (e->caps)
+                {
+                  fprintf(stderr, "%s: cannot assign capabilities for this kind of file\n", e->file+rootl);
+                  cap_free(e->caps);
+                  errors++;
+                }
+              e->caps = NULL;
+            }
+          if (errno == EOPNOTSUPP)
+            {
+              if (e->caps)
+                cap_free(e->caps);
+              e->caps = NULL;
+            }
+        }
       if (e->caps)
-	{
-	  e->mode &= 0777;
-	}
+        {
+          e->mode &= 0777;
+        }
 
       int perm_ok = (stb.st_mode & 07777) == e->mode;
       int owner_ok = stb.st_uid == uid && stb.st_gid == gid;
       int caps_ok = 0;
 
       if (!caps && !e->caps)
-	caps_ok = 1;
+        caps_ok = 1;
       else if (caps && e->caps && !cap_compare(e->caps, caps))
-	caps_ok = 1;
+        caps_ok = 1;
 
       if (perm_ok && owner_ok && caps_ok)
-	continue;
+        continue;
 
       if (!told)
-	{
-	  told = 1;
-	  printf("Checking permissions and ownerships - using the permissions files\n");
-	  for (i = 0; i < npermfiles; i++)
-	    printf("\t%s\n", permfiles[i]);
-	  if (rootl)
-	    {
-	      printf("Using root %s\n", root);
-	    }
-	}
+        {
+          told = 1;
+          printf("Checking permissions and ownerships - using the permissions files\n");
+          for (i = 0; i < npermfiles; i++)
+            printf("\t%s\n", permfiles[i]);
+          if (rootl)
+            {
+              printf("Using root %s\n", root);
+            }
+        }
 
       if (!do_set)
-	printf("%s should be %s:%s %04o", e->file+rootl, e->owner, e->group, e->mode);
+        printf("%s should be %s:%s %04o", e->file+rootl, e->owner, e->group, e->mode);
       else
-	printf("setting %s to %s:%s %04o", e->file+rootl, e->owner, e->group, e->mode);
+        printf("setting %s to %s:%s %04o", e->file+rootl, e->owner, e->group, e->mode);
 
       if (!caps_ok && e->caps)
         {
-	  str = cap_to_text(e->caps, NULL);
-	  printf(" \"%s\"", str);
-	  cap_free(str);
+          str = cap_to_text(e->caps, NULL);
+          printf(" \"%s\"", str);
+          cap_free(str);
         }
       printf(". (wrong");
       if (!owner_ok)
-	{
-	  pwd = getpwuid(stb.st_uid);
-	  grp = getgrgid(stb.st_gid);
-	  if (pwd)
-	    printf(" owner/group %s", pwd->pw_name);
-	  else
-	    printf(" owner/group %d", stb.st_uid);
-	  if (grp)
-	    printf(":%s", grp->gr_name);
-	  else
-	    printf(":%d", stb.st_gid);
-	  pwd = 0;
-	  grp = 0;
-	}
+        {
+          pwd = getpwuid(stb.st_uid);
+          grp = getgrgid(stb.st_gid);
+          if (pwd)
+            printf(" owner/group %s", pwd->pw_name);
+          else
+            printf(" owner/group %d", stb.st_uid);
+          if (grp)
+            printf(":%s", grp->gr_name);
+          else
+            printf(":%d", stb.st_gid);
+          pwd = 0;
+          grp = 0;
+        }
 
       if (!perm_ok)
-	printf(" permissions %04o", (int)(stb.st_mode & 07777));
+        printf(" permissions %04o", (int)(stb.st_mode & 07777));
 
       if (!caps_ok)
         {
-	  if (!perm_ok || !owner_ok)
-	    {
-	      fputc(',', stdout);
-	    }
-	  if (caps)
-	    {
-	      str = cap_to_text(caps, NULL);
-	      printf(" capabilities \"%s\"", str);
-	      cap_free(str);
-	    }
-	  else
-	    fputs(" missing capabilities", stdout);
+          if (!perm_ok || !owner_ok)
+            {
+              fputc(',', stdout);
+            }
+          if (caps)
+            {
+              str = cap_to_text(caps, NULL);
+              printf(" capabilities \"%s\"", str);
+              cap_free(str);
+            }
+          else
+            fputs(" missing capabilities", stdout);
         }
       putchar(')');
       putchar('\n');
 
       if (!do_set)
-	continue;
+        continue;
+
+      // don't give high privileges to files controlled by non-root users
+      if ((e->caps || (e->mode & S_ISUID) || (e->mode & S_ISGID)) && !S_ISREG(stb.st_mode) && !S_ISDIR(stb.st_mode))
+        {
+          fprintf(stderr, "%s: will only assign capabilities or setXid bits to regular files or directories\n", e->file+rootl);
+          errors++;
+          continue;
+        }
+      if (traversed_insecure && (e->caps || (e->mode & S_ISUID) || ((e->mode & S_ISGID) && S_ISREG(stb.st_mode))))
+        {
+          fprintf(stderr, "%s: will not give away capabilities or setXid bits on an insecure path\n", e->file+rootl);
+          errors++;
+          continue;
+        }
 
-      fd = -1;
-      if (S_ISDIR(stb.st_mode))
-	{
-	  fd = open(e->file, O_RDONLY|O_DIRECTORY|O_NONBLOCK|O_NOFOLLOW);
-	  if (fd == -1)
-	    {
-	      perror(e->file);
-	      errors++;
-	      continue;
-	    }
-	}
-      else if (S_ISREG(stb.st_mode))
-	{
-	  fd = open(e->file, O_RDONLY|O_NONBLOCK|O_NOFOLLOW);
-	  if (fd == -1)
-	    {
-	      perror(e->file);
-	      errors++;
-	      continue;
-	    }
-	  if (fstat(fd, &stb2))
-	    continue;
-	  if (stb.st_mode != stb2.st_mode || stb.st_nlink != stb2.st_nlink || stb.st_dev != stb2.st_dev || stb.st_ino != stb2.st_ino)
-	    {
-	      fprintf(stderr, "%s: too fluctuating\n", e->file+rootl);
-	      errors++;
-	      continue;
-	    }
-	  if (stb.st_nlink > 1 && !safepath(e->file, 0, 0))
-	    {
-	      fprintf(stderr, "%s: on an insecure path\n", e->file+rootl);
-	      errors++;
-	      continue;
-	    }
-	  else if (e->mode & 06000)
-	    {
-	      /* extra checks for s-bits */
-	      if (!safepath(e->file, (e->mode & 02000) == 0 ? uid : 0, (e->mode & 04000) == 0 ? gid : 0))
-		{
-		  fprintf(stderr, "%s: will not give away s-bits on an insecure path\n", e->file+rootl);
-		  errors++;
-		  continue;
-		}
-	    }
-	}
-      else if (strncmp(e->file, "/dev/", 5) != 0) // handle special files only in /dev
-	{
-	  fprintf(stderr, "%s: don't know what to do with that type of file\n", e->file+rootl);
-	  errors++;
-	  continue;
-	}
       if (euid == 0 && !owner_ok)
-	{
-	 /* if we change owner or group of a setuid file the bit gets reset so
-	    also set perms again */
-	  if (e->mode & 06000)
-	      perm_ok = 0;
-	  if (fd >= 0)
-	    r = fchown(fd, uid, gid);
-	  else
-	    r = chown(e->file, uid, gid);
-	  if (r)
-	    {
-	      fprintf(stderr, "%s: chown: %s\n", e->file+rootl, strerror(errno));
-	      errors++;
-	    }
-	  if (fd >= 0)
-	    r = fstat(fd, &stb);
-	  else
-	    r = lstat(e->file, &stb);
-	  if (r)
-	    {
-	      fprintf(stderr, "%s: too fluctuating\n", e->file+rootl);
-	      errors++;
-	      continue;
-	    }
-	}
-      if (!perm_ok)
-	{
-	  if (fd >= 0)
-	    r = fchmod(fd, e->mode);
-	  else
-	    r = chmod(e->file, e->mode);
-	  if (r)
-	    {
-	      fprintf(stderr, "%s: chmod: %s\n", e->file+rootl, strerror(errno));
-	      errors++;
-	    }
-	}
+        {
+         /* if we change owner or group of a setuid file the bit gets reset so
+            also set perms again */
+          if (e->mode & (S_ISUID | S_ISGID))
+              perm_ok = 0;
+          if (chown(fd_path, uid, gid))
+            {
+              fprintf(stderr, "%s: chown: %s\n", e->file+rootl, strerror(errno));
+              errors++;
+            }
+        }
+      if (!perm_ok && chmod(fd_path, e->mode))
+        {
+          fprintf(stderr, "%s: chmod: %s\n", e->file+rootl, strerror(errno));
+          errors++;
+        }
       if (!caps_ok)
-	{
-	  if (fd >= 0)
-	    r = cap_set_fd(fd, e->caps);
-	  else
-	    r = cap_set_file(e->file, e->caps);
-	  if (r)
-	    {
-	      fprintf(stderr, "%s: cap_set_file: %s\n", e->file+rootl, strerror(errno));
-	      errors++;
-	    }
-	}
-      if (fd >= 0)
-	close(fd);
+        {
+          if (S_ISREG(stb.st_mode))
+            {
+              // cap_set_file() tries to be helpful and does a lstat() to check that it isn't called on
+              // a symlink. So we have to open() it (without O_PATH) and use cap_set_fd().
+              int cap_fd = open(fd_path, O_NOATIME | O_CLOEXEC);
+              if (cap_fd == -1)
+                {
+                  fprintf(stderr, "%s: open() for changing capabilities: %s\n", e->file+rootl, strerror(errno));
+                  errors++;
+                }
+              else if (cap_set_fd(cap_fd, e->caps))
+                {
+                  fprintf(stderr, "%s: cap_set_fd: %s\n", e->file+rootl, strerror(errno));
+                  errors++;
+                }
+              if (cap_fd != -1)
+                close(cap_fd);
+            }
+          else
+            {
+              fprintf(stderr, "%s: cannot set capabilities: not a regular file\n", e->file+rootl);
+              errors++;
+            }
+        }
+    }
+  // close fd from last loop iteration
+  if (fd >= 0)
+    {
+      close(fd);
+      fd = -1;
     }
   if (errors)
     {
       fprintf(stderr, "ERROR: not all operations were successful.\n");
       exit(1);
     }
+  if (permfiles != argv + 1)
+    {
+      for (i = 0; i < npermfiles; i++)
+        {
+          free(permfiles[i]);
+        }
+      free(permfiles);
+    }
   exit(0);
 }

Places

File 0007-chkstat-fix-privesc-CVE-2019-3690.patch of Package permissions (Revision 48c60a331ca320acd5713adaaa13a905)

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