| Message ID | 1490354187-11843-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 3/24/2017 4:16 AM, Tetsuo Handa wrote: > Since commit 3dfc9b02864b19f4 ("LSM: Initialize security_hook_heads upon > registration.") changed to access security_hook_heads as an array of > "struct list_head", we no longer need to pass address of each member inside > "struct security_hook_heads". Therefore, we can make security_hook_heads > a local variable by passing index number inside "struct list_head" array. > > Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> > Cc: Kees Cook <keescook@chromium.org> > Cc: Paul Moore <paul@paul-moore.com> > Cc: Stephen Smalley <sds@tycho.nsa.gov> > Cc: Casey Schaufler <casey@schaufler-ca.com> > Cc: James Morris <james.l.morris@oracle.com> > --- > include/linux/lsm_hooks.h | 6 +++--- > security/security.c | 13 +++++++++++-- > 2 files changed, 14 insertions(+), 5 deletions(-) > > diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h > index 1aa6333..54191cf 100644 > --- a/include/linux/lsm_hooks.h > +++ b/include/linux/lsm_hooks.h > @@ -1877,8 +1877,8 @@ struct security_hook_heads { > */ > struct security_hook_list { > struct list_head list; > - struct list_head *head; > union security_list_options hook; > + const unsigned int idx; > char *lsm; > }; > > @@ -1889,9 +1889,9 @@ struct security_hook_list { > * text involved. > */ > #define LSM_HOOK_INIT(HEAD, HOOK) \ > - { .head = &security_hook_heads.HEAD, .hook = { .HEAD = HOOK } } > + { .idx = offsetof(struct security_hook_heads, HEAD) / \ > + sizeof(struct list_head), .hook = { .HEAD = HOOK } } You're gaining making security_hook_heads static, but you're loosing the type checking. I found (much to my surprise at times) that the type checking is very helpful even with existing modules. I expect some module developers to get bitten by this. > > -extern struct security_hook_heads security_hook_heads; > extern char *lsm_names; > > extern void security_add_hooks(struct security_hook_list *hooks, int count, > diff --git a/security/security.c b/security/security.c > index 2f15488..45af8fb 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -32,7 +32,7 @@ > /* Maximum number of letters for an LSM name string */ > #define SECURITY_NAME_MAX 10 > > -struct security_hook_heads security_hook_heads __lsm_ro_after_init; > +static struct security_hook_heads security_hook_heads __lsm_ro_after_init; > char *lsm_names; > /* Boot-time LSM user choice */ > static __initdata char chosen_lsm[SECURITY_NAME_MAX + 1] = > @@ -133,10 +133,19 @@ void __init security_add_hooks(struct security_hook_list *hooks, int count, > char *lsm) > { > int i; > + unsigned int idx; > + struct list_head *list = (struct list_head *) &security_hook_heads; > > for (i = 0; i < count; i++) { > hooks[i].lsm = lsm; > - list_add_tail_rcu(&hooks[i].list, hooks[i].head); > + /* > + * LSM_HOOK_INIT() must have set correct idx value. > + * But just in case something went wrong. > + */ > + idx = hooks[i].idx; > + BUG_ON(idx >= sizeof(struct security_hook_heads) / > + sizeof(struct list_head)); > + list_add_tail_rcu(&hooks[i].list, &list[idx]); > } > if (lsm_append(lsm, &lsm_names) < 0) > panic("%s - Cannot get early memory.\n", __func__); -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index 1aa6333..54191cf 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -1877,8 +1877,8 @@ struct security_hook_heads { */ struct security_hook_list { struct list_head list; - struct list_head *head; union security_list_options hook; + const unsigned int idx; char *lsm; }; @@ -1889,9 +1889,9 @@ struct security_hook_list { * text involved. */ #define LSM_HOOK_INIT(HEAD, HOOK) \ - { .head = &security_hook_heads.HEAD, .hook = { .HEAD = HOOK } } + { .idx = offsetof(struct security_hook_heads, HEAD) / \ + sizeof(struct list_head), .hook = { .HEAD = HOOK } } -extern struct security_hook_heads security_hook_heads; extern char *lsm_names; extern void security_add_hooks(struct security_hook_list *hooks, int count, diff --git a/security/security.c b/security/security.c index 2f15488..45af8fb 100644 --- a/security/security.c +++ b/security/security.c @@ -32,7 +32,7 @@ /* Maximum number of letters for an LSM name string */ #define SECURITY_NAME_MAX 10 -struct security_hook_heads security_hook_heads __lsm_ro_after_init; +static struct security_hook_heads security_hook_heads __lsm_ro_after_init; char *lsm_names; /* Boot-time LSM user choice */ static __initdata char chosen_lsm[SECURITY_NAME_MAX + 1] = @@ -133,10 +133,19 @@ void __init security_add_hooks(struct security_hook_list *hooks, int count, char *lsm) { int i; + unsigned int idx; + struct list_head *list = (struct list_head *) &security_hook_heads; for (i = 0; i < count; i++) { hooks[i].lsm = lsm; - list_add_tail_rcu(&hooks[i].list, hooks[i].head); + /* + * LSM_HOOK_INIT() must have set correct idx value. + * But just in case something went wrong. + */ + idx = hooks[i].idx; + BUG_ON(idx >= sizeof(struct security_hook_heads) / + sizeof(struct list_head)); + list_add_tail_rcu(&hooks[i].list, &list[idx]); } if (lsm_append(lsm, &lsm_names) < 0) panic("%s - Cannot get early memory.\n", __func__);
Since commit 3dfc9b02864b19f4 ("LSM: Initialize security_hook_heads upon registration.") changed to access security_hook_heads as an array of "struct list_head", we no longer need to pass address of each member inside "struct security_hook_heads". Therefore, we can make security_hook_heads a local variable by passing index number inside "struct list_head" array. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Kees Cook <keescook@chromium.org> Cc: Paul Moore <paul@paul-moore.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: Casey Schaufler <casey@schaufler-ca.com> Cc: James Morris <james.l.morris@oracle.com> --- include/linux/lsm_hooks.h | 6 +++--- security/security.c | 13 +++++++++++-- 2 files changed, 14 insertions(+), 5 deletions(-)