From cb09021616b6e5cdc505bf078838fba58e9f6309 Mon Sep 17 00:00:00 2001 From: Andrew Vagin Date: Thu, 25 Oct 2012 12:15:16 +1100 Subject: [PATCH] proc: don't show nonexistent capabilities 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. Signed-off-by: Andrew Vagin Cc: Andrew G. Morgan Reviewed-by: Serge E. Hallyn Cc: Pavel Emelyanov Reviewed-by: Kees Cook Cc: KAMEZAWA Hiroyuki Cc: James Morris Signed-off-by: Andrew Morton --- fs/proc/array.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/fs/proc/array.c b/fs/proc/array.c index c1c207c36cae..d4efc333b132 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); -- 2.39.5