On Fri, 2024-02-09 at 12:34 +0100, Christian Brauner wrote: > On Fri, Feb 09, 2024 at 11:46:16AM +0100, Roberto Sassu wrote: > > 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) > > Ah, meh. I was hoping IMA just wouldn't care about this case. Actually it doesn't. I added code to artifically create the situation (to see what happens if a new LSM does that). Roberto
