Quoting Guido Günther (agx@xxxxxxxxxxx):
> On Fri, Mar 11, 2016 at 08:07:02PM +0000, Serge Hallyn wrote:
> > [Sorry, the Ubuntu package suggests this came from Cèdric, although
> > I can't quite find this patch on the mailing list. Those patches
> > which I did see from Cèdric did not have a Signed-off-by, so I didn't
> > add one for him.]
> >
> > From: Cèdric Bosdonnat <cbosdonnat@xxxxxxxx>
> >
> > Upstream changed get_files to unconditionally be "rw" to allow audit
> > files to be written. Still under discussion but the proposed approach
> > is to have a way of saying readonly but do not implicitely create a
> > write deny rule.
> >
> > ---
> > Changelog: do not overwrite const memory, that leads to segv (serge)
> > ---
> > src/security/virt-aa-helper.c | 23 +++++++++++++++++++----
> > 1 file changed, 19 insertions(+), 4 deletions(-)
> >
> > diff --git a/src/security/virt-aa-helper.c b/src/security/virt-aa-helper.c
> > index b466626..34d08c8 100644
> > --- a/src/security/virt-aa-helper.c
> > +++ b/src/security/virt-aa-helper.c
> > @@ -785,12 +785,19 @@ get_definition(vahControl * ctl, const char *xmlStr)
> > return rc;
> > }
> >
> > +/*
> > + * The permissions allowed are apparmor valid permissions and 'R'. 'R' stands
> > + * for read with no explicit deny rule.
> > + */
> > static int
> > -vah_add_path(virBufferPtr buf, const char *path, const char *perms, bool recursive)
> > +vah_add_path(virBufferPtr buf, const char *path, const char *inperms, bool recursive)
> > {
> > char *tmp = NULL;
> > int rc = -1;
> > bool readonly = true;
> > + bool explicit_deny_rule = true;
> > + char *perms = strdupa(inperms);
>
> This would be a newcomer, the rest of the code uses VIR_STRDUP. I'm not
> sure how hard this is being "enforced" at the moment.
Good point - that should be switched over, if Jamie is ok with the patch in
general. (Note I'm out this week, I can update next week or I don't mind
if someone else take it over)
> > + char *sub = NULL;
> >
> > if (path == NULL)
> > return rc;
> > @@ -815,8 +822,16 @@ vah_add_path(virBufferPtr buf, const char *path, const char *perms, bool recursi
> > return rc;
> > }
> >
> > - if (strchr(perms, 'w') != NULL)
> > + if (strchr(perms, 'w') != NULL) {
> > readonly = false;
> > + explicit_deny_rule = false;
> > + }
> > +
> > + if ((sub = strchr(perms, 'R')) != NULL) {
> > + /* Don't write the invalid 'R' permission, replace with 'r' */
> > + sub[0] = 'r';
> > + explicit_deny_rule = false;
> > + }
> >
> > rc = valid_path(tmp, readonly);
> > if (rc != 0) {
> > @@ -831,7 +846,7 @@ vah_add_path(virBufferPtr buf, const char *path, const char *perms, bool recursi
> > tmp[strlen(tmp) - 1] = '\0';
> >
> > virBufferAsprintf(buf, " \"%s%s\" %s,\n", tmp, recursive ? "/**" : "", perms);
> > - if (readonly) {
> > + if (explicit_deny_rule) {
> > virBufferAddLit(buf, " # don't audit writes to readonly files\n");
> > virBufferAsprintf(buf, " deny \"%s%s\" w,\n", tmp, recursive ? "/**" : "");
> > }
> > @@ -1130,7 +1145,7 @@ get_files(vahControl * ctl)
> > /* We don't need to add deny rw rules for readonly mounts,
> > * this can only lead to troubles when mounting / readonly.
> > */
> > - if (vah_add_path(&buf, fs->src, "rw", true) != 0)
> > + if (vah_add_path(&buf, fs->src, fs->readonly ? "R" : "rw", true) != 0)
> > goto cleanup;
> > }
> > }
> > --
>
> This otherwise looks good to me (as does the whole series) but Jamie
> probably should comment on it.
> Cheers,
> -- Guido
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