The patch titled vfs: allow file truncations when both suid and write permissions set has been removed from the -mm tree. Its filename was vfs-allow-file-truncations-when-both-suid-and-write-permissions-set.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: vfs: allow file truncations when both suid and write permissions set From: Amerigo Wang <amwang@xxxxxxxxxx> When suid is set and the non-owner user has write permission, any writing into this file should be allowed and suid should be removed after that. However, current kernel only allows writing without truncations, when we do truncations on that file, we get EPERM. This is a bug. Steps to reproduce this bug: % ls -l rootdir/file1 -rwsrwsrwx 1 root root 3 Jun 25 15:42 rootdir/file1 % echo h > rootdir/file1 zsh: operation not permitted: rootdir/file1 % ls -l rootdir/file1 -rwsrwsrwx 1 root root 3 Jun 25 15:42 rootdir/file1 % echo h >> rootdir/file1 % ls -l rootdir/file1 -rwxrwxrwx 1 root root 5 Jun 25 16:34 rootdir/file1 Signed-off-by: WANG Cong <amwang@xxxxxxxxxx> Cc: Eric Sandeen <esandeen@xxxxxxxxxx> Acked-by: Eric Paris <eparis@xxxxxxxxxx> Cc: Eugene Teo <eteo@xxxxxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx> Cc: Christoph Hellwig <hch@xxxxxx> Cc: Stephen Smalley <sds@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/open.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff -puN fs/open.c~vfs-allow-file-truncations-when-both-suid-and-write-permissions-set fs/open.c --- a/fs/open.c~vfs-allow-file-truncations-when-both-suid-and-write-permissions-set +++ a/fs/open.c @@ -199,7 +199,7 @@ out: int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs, struct file *filp) { - int err; + int ret; struct iattr newattrs; /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */ @@ -214,12 +214,14 @@ int do_truncate(struct dentry *dentry, l } /* Remove suid/sgid on truncate too */ - newattrs.ia_valid |= should_remove_suid(dentry); + ret = should_remove_suid(dentry); + if (ret) + newattrs.ia_valid |= ret | ATTR_FORCE; mutex_lock(&dentry->d_inode->i_mutex); - err = notify_change(dentry, &newattrs); + ret = notify_change(dentry, &newattrs); mutex_unlock(&dentry->d_inode->i_mutex); - return err; + return ret; } static long do_sys_truncate(const char __user *pathname, loff_t length) _ Patches currently in -mm which might be from amwang@xxxxxxxxxx are linux-next.patch xtensa-use-generic-sys_pipe.patch kcore-fix-proc-kcores-statst_size.patch elf-clean-up-fill_note_info.patch elf-clean-up-fill_note_info-fix.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html