From 2a4c22426955d4fc04069811997b7390c0fb858e Mon Sep 17 00:00:00 2001 From: Stephen Smalley Date: Fri, 10 Mar 2017 12:14:18 -0500 Subject: [PATCH] fs: switch order of CAP_DAC_OVERRIDE and CAP_DAC_READ_SEARCH checks generic_permission() presently checks CAP_DAC_OVERRIDE prior to CAP_DAC_READ_SEARCH. This can cause misleading audit messages when using a LSM such as SELinux or AppArmor, since CAP_DAC_OVERRIDE may not be required for the operation. Flip the order of the tests so that CAP_DAC_OVERRIDE is only checked when required for the operation. Signed-off-by: Stephen Smalley Acked-by: John Johansen Reviewed-by: Serge Hallyn Acked-by: James Morris Signed-off-by: Paul Moore --- fs/namei.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index d41fab78798b..482414aa558b 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -340,22 +340,14 @@ int generic_permission(struct inode *inode, int mask) if (S_ISDIR(inode->i_mode)) { /* DACs are overridable for directories */ - if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) - return 0; if (!(mask & MAY_WRITE)) if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) return 0; - return -EACCES; - } - /* - * Read/write DACs are always overridable. - * Executable DACs are overridable when there is - * at least one exec bit set. - */ - if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) return 0; + return -EACCES; + } /* * Searching includes executable on directories, else just read. @@ -364,6 +356,14 @@ int generic_permission(struct inode *inode, int mask) if (mask == MAY_READ) if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) return 0; + /* + * Read/write DACs are always overridable. + * Executable DACs are overridable when there is + * at least one exec bit set. + */ + if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) + if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) + return 0; return -EACCES; } -- 2.20.1