Re: [PATCH 0/3] exporting capability name/code pairs (for 2.6.26)
From: KaiGai Kohei
Date: Tue Apr 22 2008 - 20:43:22 EST
Alexey Dobriyan wrote:
On Tue, Apr 22, 2008 at 08:12:15PM +0900, KaiGai Kohei wrote:
$ ls -R /sys/kernel/capability/
/sys/kernel/capability/:
codes names version
/sys/kernel/capability/codes:
0 10 12 14 16 18 2 21 23 25 27 29 30 32 4 6 8
1 11 13 15 17 19 20 22 24 26 28 3 31 33 5 7 9
/sys/kernel/capability/names:
cap_audit_control cap_kill cap_net_raw cap_sys_nice
cap_audit_write cap_lease cap_setfcap cap_sys_pacct
cap_chown cap_linux_immutable cap_setgid cap_sys_ptrace
cap_dac_override cap_mac_admin cap_setpcap cap_sys_rawio
cap_dac_read_search cap_mac_override cap_setuid cap_sys_resource
cap_fowner cap_mknod cap_sys_admin cap_sys_time
cap_fsetid cap_net_admin cap_sys_boot cap_sys_tty_config
cap_ipc_lock cap_net_bind_service cap_sys_chroot
cap_ipc_owner cap_net_broadcast cap_sys_module
$ cat /sys/kernel/capability/names/cap_sys_pacct
20
$ cat /sys/kernel/capability/codes/16
cap_sys_module
This is amazing amount of bloat for such conceptually simple feature!
Below is /proc/capabilities ,
a) without all memory eaten by sysfs files and directories,
generated on the fly
b) with capability names matching the ones in manpages
c) nicely formatted
e) with whole-whooping 2 lines of protection from fool
(including helpful directions)
Proposed regexp of course will incorrectly match someday
If this file will be used often, I can even make whole its content
become generated at compile time and then put into buffers
with 1 (one) seq_puts()!
I had suggested a similar idea previously, but it could not be supported
because it requires to scan whole of /proc/capabilities at first.
Using sysfs enables to translate them without seeking, as Andrew Morgan said.
Alexey "0 CAP_CHOWN
1 CAP_DAC_OVERRIDE
2 CAP_DAC_READ_SEARCH
3 CAP_FOWNER
4 CAP_FSETID
5 CAP_KILL
6 CAP_SETGID
7 CAP_SETUID
8 CAP_SETPCAP
9 CAP_LINUX_IMMUTABLE
10 CAP_NET_BIND_SERVICE
11 CAP_NET_BROADCAST
12 CAP_NET_ADMIN
13 CAP_NET_RAW
14 CAP_IPC_LOCK
15 CAP_IPC_OWNER
16 CAP_SYS_MODULE
17 CAP_SYS_RAWIO
18 CAP_SYS_CHROOT
19 CAP_SYS_PTRACE
20 CAP_SYS_PACCT
21 CAP_SYS_ADMIN
22 CAP_SYS_BOOT
23 CAP_SYS_NICE
24 CAP_SYS_RESOURCE
25 CAP_SYS_TIME
26 CAP_SYS_TTY_CONFIG
27 CAP_MKNOD
28 CAP_LEASE
29 CAP_AUDIT_WRITE
30 CAP_AUDIT_CONTROL
31 CAP_SETFCAP
32 CAP_MAC_OVERRIDE
33 CAP_MAC_ADMIN" Dobriyan
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -19,6 +19,8 @@
#include <linux/swap.h>
#include <linux/skbuff.h>
#include <linux/netlink.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
#include <linux/ptrace.h>
#include <linux/xattr.h>
#include <linux/hugetlb.h>
@@ -597,3 +599,81 @@ int cap_vm_enough_memory(struct mm_struct *mm, long pages)
return __vm_enough_memory(mm, pages, cap_sys_admin);
}
+#ifdef CONFIG_PROC_FS
+static const struct {
+ int val;
+ const char *str;
+} proc_cap[] = {
+#define _(cap) { .val = cap, .str = #cap }
+ _(CAP_CHOWN),
+ _(CAP_DAC_OVERRIDE),
+ _(CAP_DAC_READ_SEARCH),
+ _(CAP_FOWNER),
+ _(CAP_FSETID),
+ _(CAP_KILL),
+ _(CAP_SETGID),
+ _(CAP_SETUID),
+ _(CAP_SETPCAP),
+ _(CAP_LINUX_IMMUTABLE),
+ _(CAP_NET_BIND_SERVICE),
+ _(CAP_NET_BROADCAST),
+ _(CAP_NET_ADMIN),
+ _(CAP_NET_RAW),
+ _(CAP_IPC_LOCK),
+ _(CAP_IPC_OWNER),
+ _(CAP_SYS_MODULE),
+ _(CAP_SYS_RAWIO),
+ _(CAP_SYS_CHROOT),
+ _(CAP_SYS_PTRACE),
+ _(CAP_SYS_PACCT),
+ _(CAP_SYS_ADMIN),
+ _(CAP_SYS_BOOT),
+ _(CAP_SYS_NICE),
+ _(CAP_SYS_RESOURCE),
+ _(CAP_SYS_TIME),
+ _(CAP_SYS_TTY_CONFIG),
+ _(CAP_MKNOD),
+ _(CAP_LEASE),
+ _(CAP_AUDIT_WRITE),
+ _(CAP_AUDIT_CONTROL),
+ _(CAP_SETFCAP),
+ _(CAP_MAC_OVERRIDE),
+ _(CAP_MAC_ADMIN),
+#undef _
It should be generated automatically.
and, where is the "version" information?
+};
+
+static int proc_capabilities_show(struct seq_file *m, void *v)
+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(proc_cap); i++)
+ seq_printf(m, "%d\t%s\n", proc_cap[i].val, proc_cap[i].str);
+ return 0;
+}
+
+static int proc_capabilities_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, proc_capabilities_show, NULL);
+}
+
+static const struct file_operations capabilities_proc_fops = {
+ .owner = THIS_MODULE,
+ .open = proc_capabilities_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static int __init commoncap_init(void)
+{
+ struct proc_dir_entry *pde;
+
+ pde = proc_create("capabilities", 0, NULL, &capabilities_proc_fops);
+ if (!pde)
+ return -ENOMEM;
+ /* Forgot to add new capability to proc_cap array? */
+ BUILD_BUG_ON(ARRAY_SIZE(proc_cap) != CAP_LAST_CAP + 1);
+ return 0;
+}
+module_init(commoncap_init);
+#endif
--
OSS Platform Development Division, NEC
KaiGai Kohei <kaigai@xxxxxxxxxxxxx>
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