massage generic_permission() to treat directories on a separate path

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 13 insertions, 4 deletions

diff --git a/fs/namei.c b/fs/namei.c
index 21eba95368f2..758bae739305 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -235,12 +235,21 @@ int generic_permission(struct inode *inode, int mask)
         if (ret != -EACCES)
                 return ret;
 
+        if (S_ISDIR(inode->i_mode)) {
+                /* DACs are overridable for directories */
+                if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE))
+                        return 0;
+                if (!(mask & MAY_WRITE))
+                        if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH))
+                                return 0;
+                return -EACCES;
+        }
         /*
          * Read/write DACs are always overridable.
-         * Executable DACs are overridable for all directories and
-         * for non-directories that have least one exec bit set.
+         * Executable DACs are overridable when there is
+         * at least one exec bit set.
          */
-        if (!(mask & MAY_EXEC) || execute_ok(inode))
+        if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO))
                 if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE))
                         return 0;
 
@@ -248,7 +257,7 @@ int generic_permission(struct inode *inode, int mask)
          * Searching includes executable on directories, else just read.
          */
         mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
-        if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE)))
+        if (mask == MAY_READ)
                 if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH))
                         return 0;