->permission() sanitizing: MAY_NOT_BLOCK

Duplicate the flags argument into mask bitmap.

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

3 files changed, 7 insertions, 3 deletions

diff --git a/fs/namei.c b/fs/namei.c
index c5af0f37e67d..723a3fe4bc40 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -318,13 +318,16 @@ static inline int exec_permission(struct inode *inode, unsigned int flags)
 {
         int ret;
         struct user_namespace *ns = inode_userns(inode);
+        int mask = MAY_EXEC;
+        if (flags & IPERM_FLAG_RCU)
+                mask |= MAY_NOT_BLOCK;
 
         if (inode->i_op->permission) {
-                ret = inode->i_op->permission(inode, MAY_EXEC, flags);
+                ret = inode->i_op->permission(inode, mask, flags);
                 if (likely(!ret))
                         goto ok;
         } else {
-                ret = acl_permission_check(inode, MAY_EXEC, flags);
+                ret = acl_permission_check(inode, mask, flags);
                 if (likely(!ret))
                         goto ok;
                 if (ret != -EACCES)
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index d167de365a8d..349b22f434d8 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -316,7 +316,7 @@ static int proc_sys_permission(struct inode *inode, int mask,unsigned int flags)
         if (!table) /* global root - r-xr-xr-x */
                 error = mask & MAY_WRITE ? -EACCES : 0;
         else /* Use the permissions on the sysctl table entry */
-                error = sysctl_perm(head->root, table, mask);
+                error = sysctl_perm(head->root, table, mask & ~MAY_NOT_BLOCK);
 
         sysctl_head_finish(head);
         return error;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 0c15d5e459d5..60c1fe65bb2d 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -63,6 +63,7 @@ struct inodes_stat_t {
 #define MAY_ACCESS 16
 #define MAY_OPEN 32
 #define MAY_CHDIR 64
+#define MAY_NOT_BLOCK 128       /* called from RCU mode, don't block */
 
 /*
  * flags in file.f_mode.  Note that FMODE_READ and FMODE_WRITE must correspond