Abhishekmishra2808 commented on code in PR #18902:
URL: https://github.com/apache/nuttx/pull/18902#discussion_r3273122002
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fs/inode/fs_inode.c:
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@@ -121,49 +122,89 @@ void inode_runlock(void)
}
/****************************************************************************
- * Name: inode_checkperm
+ * Name: _inode_checkmode
*
* Description:
- * Validate that 'inode' can be opened with the access described by
- * 'oflags'. Two sequential checks are performed:
+ * Test effective credentials against 'inode' for 'amode' access.
+ * Kernel threads always pass.
*
- * 1. Operation-support check (all inode types, unconditional):
- * Verifies the driver exposes the read/write entry points required by
- * 'oflags'. Returns -ENXIO when ops are NULL and -EACCES when the
- * required entry point is absent. Pseudo-directory inodes
- * (INODE_IS_PSEUDODIR) are exempted from this step.
+ * Returned Value:
+ * Zero (OK) or -EACCES.
*
- * 2. UNIX permission check (pseudo-filesystem inodes only):
- * Compares effective uid/gid against i_mode owner/group/other bits.
- * Mountpoint inodes and kernel threads are unconditionally exempted.
- * Requires CONFIG_PSEUDOFS_ATTRIBUTES and CONFIG_SCHED_USER_IDENTITY;
- * when either option is disabled this step is a no-op.
+ ****************************************************************************/
+
+#if defined(CONFIG_PSEUDOFS_ATTRIBUTES) && defined(CONFIG_SCHED_USER_IDENTITY)
+static int _inode_checkmode(FAR struct inode *inode, int amode)
+{
+ FAR struct tcb_s *rtcb;
+ mode_t perm;
+ uid_t uid;
+ gid_t gid;
+
+ /* Kernel threads are always granted access */
+
+ rtcb = nxsched_self();
+ if ((rtcb->flags & TCB_FLAG_TTYPE_MASK) == TCB_FLAG_TTYPE_KERNEL)
+ {
+ return OK;
+ }
+
+ /* Use effective credentials */
+
+ DEBUGASSERT(rtcb->group != NULL);
+ uid = rtcb->group->tg_euid;
+ gid = rtcb->group->tg_egid;
+
+ /* Select the applicable permission-bit triplet */
+
+ if (uid == inode->i_owner)
+ {
+ perm = (inode->i_mode >> 6) & 7;
+ }
+ else if (gid == inode->i_group)
+ {
+ perm = (inode->i_mode >> 3) & 7;
+ }
+ else
+ {
+ perm = inode->i_mode & 7;
+ }
+
+ /* Every requested bit must be present in the selected triplet */
+
+ if ((amode & perm) != amode)
+ {
+ return -EACCES;
+ }
+
+ return OK;
+}
+#endif /* CONFIG_PSEUDOFS_ATTRIBUTES && CONFIG_SCHED_USER_IDENTITY */
+
+/****************************************************************************
+ * Name: inode_checkperm
+ *
+ * Description:
+ * Validate open access to 'inode' for 'oflags'. Checks driver operation
+ * support, then pseudo-filesystem mode bits when enabled. Mountpoints
+ * are exempt from mode checks.
*
* Input Parameters:
* inode - The inode to check
* oflags - Open flags (O_RDONLY / O_WRONLY / O_RDWR)
*
* Returned Value:
- * Zero (OK) on success. Negated errno on failure:
- * -ENXIO ops pointer is NULL
- * -EACCES required operation not supported, or permission denied
+ * Zero (OK) on success, or a negated errno on failure.
*
****************************************************************************/
int inode_checkperm(FAR struct inode *inode, int oflags)
{
#if defined(CONFIG_PSEUDOFS_ATTRIBUTES) && defined(CONFIG_SCHED_USER_IDENTITY)
- FAR struct tcb_s *rtcb;
- mode_t perm;
- uid_t uid;
- gid_t gid;
+ int amode = 0;
#endif
FAR const struct file_operations *ops;
- /* === Step 1: operation-support check === */
-
- /* Pseudo-directories carry no ops and are always accessible */
-
if (INODE_IS_PSEUDODIR(inode))
Review Comment:
Yes, I updated it to follow the same permission rule used for regular
folders :-)
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