From: Michael Orlitzky <michael@orlitzky.com>
Date: Sun, 12 Aug 2012 16:35:56 +0000 (-0400)
Subject: Implement the reapply_default_acl function.
X-Git-Tag: v0.0.1~21
X-Git-Url: https://gitweb.michael.orlitzky.com/?p=apply-default-acl.git;a=commitdiff_plain;h=97a849f60570c2174bf0397311498f29d5b9155a

Implement the reapply_default_acl function.
---

diff --git a/src/aclq.c b/src/aclq.c
index 4f9ad72..6ea2e1d 100644
--- a/src/aclq.c
+++ b/src/aclq.c
@@ -1,14 +1,77 @@
 #include <errno.h>
+#include <libgen.h> /* dirname() */
 #include <limits.h> /* PATH_MAX */
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
 
 /* ACLs */
 #include <sys/types.h>
 #include <sys/acl.h>
 
 
+mode_t get_mode(const char* path) {
+  if (path == NULL) {
+    errno = ENOENT;
+    return -1;
+  }
+
+  struct stat s;
+  int result = stat(path, &s);
+  
+  if (result == 0) {
+    return s.st_mode;
+  }
+  else {
+    /* errno will be set already by stat() */
+    return result;
+  }
+}
+
+bool mode_has_perm(mode_t mode, int perm) {
+  if (mode & perm) {
+    return true;
+  }
+  else {
+    return false;
+  }
+}
+
+
+bool is_regular_file(const char* path) {
+  if (path == NULL) {
+    return false;
+  }
+
+  struct stat s;
+  int result = stat(path, &s);
+  if (result == 0) {
+    return S_ISREG(s.st_mode);
+  }
+  else {
+    return false;
+  }
+}
+
+bool is_directory(const char* path) {
+  if (path == NULL) {
+    return false;
+  }
+
+  struct stat s;
+  int result = stat(path, &s);
+  if (result == 0) {
+    return S_ISDIR(s.st_mode);
+  }
+  else {
+    return false;
+  }
+}
+
+
 bool has_default_acl(const char* path) {
   /* Return true if the given path has a default ACL, false
      otherwise. */
@@ -80,22 +143,21 @@ bool has_default_group_obj_acl(const char* path) {
   return has_default_tag_acl(path, ACL_GROUP_OBJ);
 }
 
-bool has_default_other_obj_acl(const char* path) {
+bool has_default_other_acl(const char* path) {
   return has_default_tag_acl(path, ACL_OTHER);
 }
 
 
-int get_default_tag_permset(const char* path,
+bool get_default_tag_permset(const char* path,
 			    acl_tag_t tag_type,
 			    acl_permset_t* output_perms) {
-  /* Returns 0 if successful or -1 on error in accordance with
-     acl_get_permset. */
+  /* Returns true if successful or false on error */
   acl_t defacl = acl_get_file(path, ACL_TYPE_DEFAULT);
   
   if (defacl == (acl_t)NULL) {
     /* Follow the acl_foo convention of -1 == error. */
     errno = EINVAL;
-    return -1;
+    return false;
   }
 
   acl_entry_t entry;
@@ -107,12 +169,18 @@ int get_default_tag_permset(const char* path,
     
     if (tag_result == -1) {
        perror("get_default_tag_permset");
-       return -1;
+       return false;
     }
     else {
       if (tag == tag_type) {
 	/* We found the right tag, now get the permset. */
-	return acl_get_permset(entry, output_perms);
+	int ps_result = acl_get_permset(entry, output_perms);
+	if (ps_result == 0) {
+	  return true;
+	}
+	else {
+	  return false;
+	}
       }
     }
     
@@ -120,32 +188,39 @@ int get_default_tag_permset(const char* path,
   }
 
   errno = EINVAL;
-  return -1;
+  return false;
 }
 
-int get_default_user_obj_permset(const char* path,
+bool get_default_user_obj_permset(const char* path,
 				 acl_permset_t* output_perms) {
   return get_default_tag_permset(path, ACL_USER_OBJ, output_perms);
 }
 
-int get_default_group_obj_permset(const char* path,
+bool get_default_group_obj_permset(const char* path,
 				 acl_permset_t* output_perms) {
   return get_default_tag_permset(path, ACL_GROUP_OBJ, output_perms);
 }
 
-int get_default_other_obj_permset(const char* path,
+bool get_default_other_permset(const char* path,
 				 acl_permset_t* output_perms) {
   return get_default_tag_permset(path, ACL_OTHER, output_perms);
 }
 
 
 
-bool has_default_tag_perm(const char* path, acl_perm_t, perm) {
+bool has_default_tag_perm(const char* path,
+			  acl_tag_t tag,
+			  acl_perm_t perm) {
+  /* Check path to see if tag has perm. */
+
+  if (!has_default_tag_acl(path, tag)) {
+    return false;
+  }
+  
   acl_permset_t permset;
-  int ps_result = get_default_tag_permset(path, tag, &permset);
+  bool ps_result = get_default_tag_permset(path, tag, &permset);
 
-  if (ps_result == -1) {
-    perror("has_default_tag_perm - get_default_tag_permset");
+  if (!ps_result) {
     return false;
   }
 
@@ -153,76 +228,162 @@ bool has_default_tag_perm(const char* path, acl_perm_t, perm) {
   if (p_result == 1) {
     return true;
   }
-  else if (p_result == 0) {
-    return false;
-  }
   else {
-    /* p_result == -1 */
-    perror("has_default_tag_perm - get_default_tag_permset");
     return false;
   }
 }
 
 bool has_default_user_obj_read(const char* path) {
-  return has_default_tag_perm(ACL_USER_OBJ, ACL_READ);
+  return has_default_tag_perm(path, ACL_USER_OBJ, ACL_READ);
 }
 
 bool has_default_user_obj_write(const char* path) {
-  return has_default_tag_perm(ACL_USER_OBJ, ACL_WRITE);
+  return has_default_tag_perm(path, ACL_USER_OBJ, ACL_WRITE);
 }
 
 bool has_default_user_obj_execute(const char* path) {
-  return has_default_tag_perm(ACL_USER_OBJ, ACL_EXECUTE);
+  return has_default_tag_perm(path, ACL_USER_OBJ, ACL_EXECUTE);
+}
+
+bool has_default_group_obj_read(const char* path) {
+  return has_default_tag_perm(path, ACL_GROUP_OBJ, ACL_READ);
+}
+
+bool has_default_group_obj_write(const char* path) {
+  return has_default_tag_perm(path, ACL_GROUP_OBJ, ACL_WRITE);
+}
+
+bool has_default_group_obj_execute(const char* path) {
+  return has_default_tag_perm(path, ACL_GROUP_OBJ, ACL_EXECUTE);
+}
+
+bool has_default_other_read(const char* path) {
+  return has_default_tag_perm(path, ACL_OTHER, ACL_READ);
+}
+
+bool has_default_other_write(const char* path) {
+  return has_default_tag_perm(path, ACL_OTHER, ACL_WRITE);
+}
+
+bool has_default_other_execute(const char* path) {
+  return has_default_tag_perm(path, ACL_OTHER, ACL_EXECUTE);
+}
+
+bool has_default_mask_read(const char* path) {
+  return has_default_tag_perm(path, ACL_MASK, ACL_READ);
+}
+
+bool has_default_mask_write(const char* path) {
+  return has_default_tag_perm(path, ACL_MASK, ACL_WRITE);
+}
+
+bool has_default_mask_execute(const char* path) {
+  return has_default_tag_perm(path, ACL_MASK, ACL_EXECUTE);
 }
 
+
+bool reapply_default_acl(const char* path) {
+  /* If this is a normal file or directory (i.e. that has just been
+     created), we proceed to find its parent directory which will have
+     a default ACL. */
+  if (path == NULL) {
+    return false;
+  }
+
+  if (!is_regular_file(path) && !is_directory(path)) {
+    return false;
+  }
+
+  /* dirname mangles its argument */
+  char path_copy[PATH_MAX];
+  strncpy(path_copy, path, PATH_MAX-1);
+  path_copy[PATH_MAX] = 0;
+
+  char* parent = dirname(path_copy);
+  if (!is_directory(parent)) {
+    /* Make sure dirname() did what we think it did. */
+    return false;
+  }
+
+  /* This is the original mode of path. We will simply add permissions
+     to it, and then later reapply the result via chmod. */
+  mode_t path_mode = get_mode(path);
+
+  
+  /* If parent has a default user ACL, apply it to path via chmod. */
+  if (has_default_user_obj_read(parent)) {
+    path_mode |= S_IRUSR;
+  }
+  
+  if (has_default_user_obj_write(parent)) {
+    path_mode |= S_IWUSR;
+  }
+
+  /* However, we don't want to set the execute bit on via the ACL
+     unless it was on originally. Furthermore, if the ACL denies
+     execute, we want to honor that. */
+  if (has_default_user_obj_acl(parent)) {
+    if (!has_default_user_obj_execute(parent)) {
+      /* It has a user ACL, but no user execute is granted. */
+      path_mode &= ~S_IXUSR;
+    }
+  }
+
+
+  /* Do the same thing with the other perms/ACL. */
+  if (has_default_other_read(parent)) {
+    path_mode |= S_IROTH;
+  }
+  
+  if (has_default_other_write(parent)) {
+    path_mode |= S_IWOTH;
+  }
+
+  if (has_default_other_acl(parent)) {
+    if (!has_default_other_execute(parent)) {
+      /* It has an other ACL, but no other execute is granted. */
+      path_mode &= ~S_IXOTH;
+    }
+  }
+
+  /* For the group bits, we'll use the ACL's mask instead of the group
+     object bits. If the default ACL had a group entry, it should
+     already have propagated (but might be masked. */
+  if (has_default_mask_read(parent)) {
+    path_mode |= S_IRGRP;
+  }
+  
+  if (has_default_mask_write(parent)) {
+    path_mode |= S_IWGRP;
+  }
+
+  /* Honor the mask execute unconditionally. */
+  if (has_default_mask_execute(parent)) {
+    if (mode_has_perm(path_mode, S_IXGRP)) {
+      path_mode |= S_IXGRP;
+    }
+  }
+
+  int result = chmod(path, path_mode);
+  if (result == 0) {
+    return true;
+  }
+  else {
+    return false;
+  }
+}
+
+
 int main(int argc, char* argv[]) {
    const char* target = argv[1];
-   printf("Target: %s\n", target);
    
-   if (has_default_acl(target)) {
-     printf("Target has a default ACL.\n");
-   }
-   else {
-     printf("Target does not have a default ACL.\n");
-   }
-
-   if (has_default_user_obj_acl(target)) {
-     printf("Target has a default owner ACL.\n");
-     acl_permset_t owner_perms;
-     get_default_user_obj_permset(target, &owner_perms);
-     if (acl_get_perm(owner_perms, ACL_READ) == 1) {
-       printf("User: read\n");
-     }
-     if (acl_get_perm(owner_perms, ACL_WRITE) == 1) {
-       printf("User: write\n");
-     }
-     if (acl_get_perm(owner_perms, ACL_EXECUTE) == 1) {
-       printf("User: execute\n");
-     }
-   }
-   else {
-     printf("Target does not have a default owner ACL.\n");
-   }
-
-   if (has_default_group_obj_acl(target)) {
-     printf("Target has a default group ACL.\n");
-   }
-   else {
-     printf("Target does not have a default group ACL.\n");
-   }
+   bool result = reapply_default_acl(target);
 
-   if (has_default_other_obj_acl(target)) {
-     printf("Target has a default other ACL.\n");
+   if (result) {
+     printf("Success.\n");
+     return EXIT_SUCCESS;
    }
    else {
-     printf("Target does not have a default other ACL.\n");
+     return EXIT_FAILURE;
    }
-   /*
-   acl_permset_t group_perms;
-   get_default_group_obj_permset();
-
-   acl_permset_t other_perms;
-   get_default_other_obj_permset();
-   */
-   return EXIT_SUCCESS;
 }