[PATCH] inode_change_ok() grpid bug?

From: Jay Miller (jnmiller@colorado.edu)
Date: Wed Feb 07 2001 - 15:19:08 EST


I think I found a reŠlly minor problem..

* 'chmod g+s foo' when I am not in foo's group does nothing. (no error)
* 'chmod g-s foo' when I am not in foo's group turns off the GID bit.

This seems like inconsistent/wrong behavior. It apparently stems from the
fact that if there is a group mismatch between the current process and the
inode, inode_change_ok() and inode_setattr() just turn S_ISGID off, as they
have no way of knowing the original state of the bit.

My lame suggestions (to 2.4.1) are below - I apologize if this is old news
or in fact correct behavior.

-- 
Jay Miller

diff -urN linux/fs/attr.c linux-j/fs/attr.c --- linux/fs/attr.c Mon Oct 16 14:00:53 2000 +++ linux-j/fs/attr.c Wed Feb 7 13:10:06 2001 @@ -43,7 +43,7 @@ /* Also check the setgid bit! */ if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid : inode->i_gid) && !capable(CAP_FSETID)) - attr->ia_mode &= ~S_ISGID; + goto error; } /* Check for setting the inode time. */ @@ -73,11 +73,8 @@ inode->i_mtime = attr->ia_mtime; if (ia_valid & ATTR_CTIME) inode->i_ctime = attr->ia_ctime; - if (ia_valid & ATTR_MODE) { + if (ia_valid & ATTR_MODE) inode->i_mode = attr->ia_mode; - if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID)) - inode->i_mode &= ~S_ISGID; - } mark_inode_dirty(inode); }

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This archive was generated by hypermail 2b29 : Wed Feb 07 2001 - 21:00:27 EST