Without this patch it is really hard to interpret a bounding set, if CAP_LAST_CAP is unknown for a current kernel.
Non-existant capabilities can not be deleted from a bounding set with help of prctl. E.g.: Here are two examples without/with this patch. CapBnd: ffffffe0fdecffff CapBnd: 00000000fdecffff I suggest to hide non-existent capabilities. Here is two reasons. * It's logically and easier for using. * It helps to checkpoint-restore capabilities of tasks, because tasks can be restored on another kernel, where CAP_LAST_CAP is bigger. v2: Non-existent capabilities can not be removed from creds, because in this case user cannot set all=eip. This patch cleans up non-existent capabilities from content of /proc/pid/status Cc: Andrew G. Morgan <mor...@kernel.org> Cc: Serge Hallyn <serge.hal...@canonical.com> Cc: Pavel Emelyanov <xe...@parallels.com> Cc: Andrew Morton <a...@linux-foundation.org> Cc: Kees Cook <keesc...@chromium.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hir...@jp.fujitsu.com> Signed-off-by: Andrew Vagin <ava...@openvz.org> --- fs/proc/array.c | 9 +++++++++ 1 files changed, 9 insertions(+), 0 deletions(-) diff --git a/fs/proc/array.c b/fs/proc/array.c index c5db89c..c814ba5 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -308,6 +308,10 @@ static void render_cap_t(struct seq_file *m, const char *header, seq_putc(m, '\n'); } +/* Remove non-existent capabilities */ +#define NORM_CAPS(v) (v.cap[CAP_TO_INDEX(CAP_LAST_CAP)] &= \ + CAP_TO_MASK(CAP_LAST_CAP + 1) - 1) + static inline void task_cap(struct seq_file *m, struct task_struct *p) { const struct cred *cred; @@ -321,6 +325,11 @@ static inline void task_cap(struct seq_file *m, struct task_struct *p) cap_bset = cred->cap_bset; rcu_read_unlock(); + NORM_CAPS(cap_inheritable); + NORM_CAPS(cap_permitted); + NORM_CAPS(cap_effective); + NORM_CAPS(cap_bset); + render_cap_t(m, "CapInh:\t", &cap_inheritable); render_cap_t(m, "CapPrm:\t", &cap_permitted); render_cap_t(m, "CapEff:\t", &cap_effective); -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/