On Fri, 2024-02-09 at 11:12 +0100, Christian Brauner wrote: > On Mon, Jan 15, 2024 at 07:17:56PM +0100, Roberto Sassu wrote: > > From: Roberto Sassu <roberto.sassu@xxxxxxxxxx> > > > > In preparation to move IMA and EVM to the LSM infrastructure, introduce the > > file_post_open hook. Also, export security_file_post_open() for NFS. > > > > Based on policy, IMA calculates the digest of the file content and > > extends the TPM with the digest, verifies the file's integrity based on > > the digest, and/or includes the file digest in the audit log. > > > > LSMs could similarly take action depending on the file content and the > > access mask requested with open(). > > > > The new hook returns a value and can cause the open to be aborted. > > > > Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx> > > Reviewed-by: Stefan Berger <stefanb@xxxxxxxxxxxxx> > > Acked-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx> > > Reviewed-by: Mimi Zohar <zohar@xxxxxxxxxxxxx> > > --- > > fs/namei.c | 2 ++ > > fs/nfsd/vfs.c | 6 ++++++ > > include/linux/lsm_hook_defs.h | 1 + > > include/linux/security.h | 6 ++++++ > > security/security.c | 17 +++++++++++++++++ > > 5 files changed, 32 insertions(+) > > > > diff --git a/fs/namei.c b/fs/namei.c > > index 71c13b2990b4..fb93d3e13df6 100644 > > --- a/fs/namei.c > > +++ b/fs/namei.c > > @@ -3620,6 +3620,8 @@ static int do_open(struct nameidata *nd, > > error = may_open(idmap, &nd->path, acc_mode, open_flag); > > if (!error && !(file->f_mode & FMODE_OPENED)) > > error = vfs_open(&nd->path, file); > > + if (!error) > > + error = security_file_post_open(file, op->acc_mode); > > What does it do for O_CREAT? IOW, we managed to create that thing and we > managed to open that thing. Can security_file_post_open() and > ima_file_check() fail afterwards even for newly created files? $ strace touch test-file ... openat(AT_FDCWD, "test-file", O_WRONLY|O_CREAT|O_NOCTTY|O_NONBLOCK, 0666) = -1 EPERM (Operation not permitted) The open fails, but the file is there. I didn't see warnings/errors in the kernel log. Roberto
