Re: [2.6 patch] remove securebits
From: Serge E. Hallyn
Date: Fri Aug 24 2007 - 17:19:58 EST
Quoting Adrian Bunk (bunk@xxxxxxxxxx):
> It seems that since it was added in kernel 2.2.0 (sic) securebits
> was never used.
>
> This patch therefore removes it.
Actually IIUC Andrew Morgan had plans of making securebits per-process,
which would make them far more usable.
Now maybe he'd just as soon start with a clean slate... Andrew?
-serge
> Signed-off-by: Adrian Bunk <bunk@xxxxxxxxxx>
>
> ---
>
> include/linux/sched.h | 1 -
> include/linux/securebits.h | 30 ------------------------------
> kernel/capability.c | 1 -
> security/commoncap.c | 34 ++++++++++++++--------------------
> security/dummy.c | 16 +++++++---------
> 5 files changed, 21 insertions(+), 61 deletions(-)
>
> 30c1d49582d183ea4a7ee0ffd886dcd9e2344115
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 2b3c936..be2e9c4 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -67,7 +67,6 @@ struct sched_param {
> #include <linux/smp.h>
> #include <linux/sem.h>
> #include <linux/signal.h>
> -#include <linux/securebits.h>
> #include <linux/fs_struct.h>
> #include <linux/compiler.h>
> #include <linux/completion.h>
> diff --git a/include/linux/securebits.h b/include/linux/securebits.h
> deleted file mode 100644
> index 5b06178..0000000
> --- a/include/linux/securebits.h
> +++ /dev/null
> @@ -1,30 +0,0 @@
> -#ifndef _LINUX_SECUREBITS_H
> -#define _LINUX_SECUREBITS_H 1
> -
> -#define SECUREBITS_DEFAULT 0x00000000
> -
> -extern unsigned securebits;
> -
> -/* When set UID 0 has no special privileges. When unset, we support
> - inheritance of root-permissions and suid-root executable under
> - compatibility mode. We raise the effective and inheritable bitmasks
> - *of the executable file* if the effective uid of the new process is
> - 0. If the real uid is 0, we raise the inheritable bitmask of the
> - executable file. */
> -#define SECURE_NOROOT 0
> -
> -/* When set, setuid to/from uid 0 does not trigger capability-"fixes"
> - to be compatible with old programs relying on set*uid to loose
> - privileges. When unset, setuid doesn't change privileges. */
> -#define SECURE_NO_SETUID_FIXUP 2
> -
> -/* Each securesetting is implemented using two bits. One bit specify
> - whether the setting is on or off. The other bit specify whether the
> - setting is fixed or not. A setting which is fixed cannot be changed
> - from user-level. */
> -
> -#define issecure(X) ( (1 << (X+1)) & SECUREBITS_DEFAULT ? \
> - (1 << (X)) & SECUREBITS_DEFAULT : \
> - (1 << (X)) & securebits )
> -
> -#endif /* !_LINUX_SECUREBITS_H */
> diff --git a/kernel/capability.c b/kernel/capability.c
> index 20914d8..d3696a9 100644
> --- a/kernel/capability.c
> +++ b/kernel/capability.c
> @@ -15,7 +15,6 @@
> #include <linux/pid_namespace.h>
> #include <asm/uaccess.h>
>
> -unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
> kernel_cap_t cap_bset = CAP_INIT_EFF_SET;
>
> /*
> diff --git a/security/commoncap.c b/security/commoncap.c
> index ff87b80..ce8f686 100644
> --- a/security/commoncap.c
> +++ b/security/commoncap.c
> @@ -241,14 +241,12 @@ int cap_bprm_set_security (struct linux_binprm *bprm)
> * and permitted sets of the executable file.
> */
>
> - if (!issecure (SECURE_NOROOT)) {
> - if (bprm->e_uid == 0 || current->uid == 0) {
> - cap_set_full (bprm->cap_inheritable);
> - cap_set_full (bprm->cap_permitted);
> - }
> - if (bprm->e_uid == 0)
> - bprm->cap_effective = true;
> + if (bprm->e_uid == 0 || current->uid == 0) {
> + cap_set_full (bprm->cap_inheritable);
> + cap_set_full (bprm->cap_permitted);
> }
> + if (bprm->e_uid == 0)
> + bprm->cap_effective = true;
>
> return ret;
> }
> @@ -393,9 +391,7 @@ int cap_task_post_setuid (uid_t old_ruid, uid_t old_euid, uid_t old_suid,
> case LSM_SETID_ID:
> case LSM_SETID_RES:
> /* Copied from kernel/sys.c:setreuid/setuid/setresuid. */
> - if (!issecure (SECURE_NO_SETUID_FIXUP)) {
> - cap_emulate_setxuid (old_ruid, old_euid, old_suid);
> - }
> + cap_emulate_setxuid (old_ruid, old_euid, old_suid);
> break;
> case LSM_SETID_FS:
> {
> @@ -408,16 +404,14 @@ int cap_task_post_setuid (uid_t old_ruid, uid_t old_euid, uid_t old_suid,
> * if not, we might be a bit too harsh here.
> */
>
> - if (!issecure (SECURE_NO_SETUID_FIXUP)) {
> - if (old_fsuid == 0 && current->fsuid != 0) {
> - cap_t (current->cap_effective) &=
> - ~CAP_FS_MASK;
> - }
> - if (old_fsuid != 0 && current->fsuid == 0) {
> - cap_t (current->cap_effective) |=
> - (cap_t (current->cap_permitted) &
> - CAP_FS_MASK);
> - }
> + if (old_fsuid == 0 && current->fsuid != 0) {
> + cap_t (current->cap_effective) &=
> + ~CAP_FS_MASK;
> + }
> + if (old_fsuid != 0 && current->fsuid == 0) {
> + cap_t (current->cap_effective) |=
> + (cap_t (current->cap_permitted) &
> + CAP_FS_MASK);
> }
> break;
> }
> diff --git a/security/dummy.c b/security/dummy.c
> index 6999456..88bb1bc 100644
> --- a/security/dummy.c
> +++ b/security/dummy.c
> @@ -37,15 +37,13 @@ static int dummy_capget (struct task_struct *target, kernel_cap_t * effective,
> kernel_cap_t * inheritable, kernel_cap_t * permitted)
> {
> *effective = *inheritable = *permitted = 0;
> - if (!issecure(SECURE_NOROOT)) {
> - if (target->euid == 0) {
> - *permitted |= (~0 & ~CAP_FS_MASK);
> - *effective |= (~0 & ~CAP_TO_MASK(CAP_SETPCAP) & ~CAP_FS_MASK);
> - }
> - if (target->fsuid == 0) {
> - *permitted |= CAP_FS_MASK;
> - *effective |= CAP_FS_MASK;
> - }
> + if (target->euid == 0) {
> + *permitted |= (~0 & ~CAP_FS_MASK);
> + *effective |= (~0 & ~CAP_TO_MASK(CAP_SETPCAP) & ~CAP_FS_MASK);
> + }
> + if (target->fsuid == 0) {
> + *permitted |= CAP_FS_MASK;
> + *effective |= CAP_FS_MASK;
> }
> return 0;
> }
>
> -
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