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.
> + 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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