From 3093d39c9361dae001efaea9279b0b23e38f049c Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 12 Jan 2008 14:06:34 -0800 Subject: Use access mode instead of open flags to determine needed permissions (CVE-2008-0001) patch 974a9f0b47da74e28f68b9c8645c3786aa5ace1a in mainline Way back when (in commit 834f2a4a1554dc5b2598038b3fe8703defcbe467, aka "VFS: Allow the filesystem to return a full file pointer on open intent" to be exact), Trond changed the open logic to keep track of the original flags to a file open, in order to pass down the the intent of a dentry lookup to the low-level filesystem. However, when doing that reorganization, it changed the meaning of namei_flags, and thus inadvertently changed the test of access mode for directories (and RO filesystem) to use the wrong flag. So fix those test back to use access mode ("acc_mode") rather than the open flag ("flag"). Issue noticed by Bill Roman at Datalight. Reported-and-tested-by: Bill Roman Acked-by: Trond Myklebust Acked-by: Al Viro Cc: Christoph Hellwig Cc: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/namei.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index a83160acd748..314afe608891 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1576,7 +1576,7 @@ int may_open(struct nameidata *nd, int acc_mode, int flag) if (S_ISLNK(inode->i_mode)) return -ELOOP; - if (S_ISDIR(inode->i_mode) && (flag & FMODE_WRITE)) + if (S_ISDIR(inode->i_mode) && (acc_mode & MAY_WRITE)) return -EISDIR; error = vfs_permission(nd, acc_mode); @@ -1595,7 +1595,7 @@ int may_open(struct nameidata *nd, int acc_mode, int flag) return -EACCES; flag &= ~O_TRUNC; - } else if (IS_RDONLY(inode) && (flag & FMODE_WRITE)) + } else if (IS_RDONLY(inode) && (acc_mode & MAY_WRITE)) return -EROFS; /* * An append-only file must be opened in append mode for writing. -- cgit v1.2.3