aboutsummaryrefslogtreecommitdiffstats
path: root/include/linux/prctl.h
diff options
context:
space:
mode:
authorAndrew G. Morgan <morgan@kernel.org>2008-04-28 05:13:40 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-28 11:58:26 -0400
commit3898b1b4ebff8dcfbcf1807e0661585e06c9a91c (patch)
tree69a338864dfe654f68064a599c5d0da460df34ac /include/linux/prctl.h
parent4016a1390d07f15b267eecb20e76a48fd5c524ef (diff)
capabilities: implement per-process securebits
Filesystem capability support makes it possible to do away with (set)uid-0 based privilege and use capabilities instead. That is, with filesystem support for capabilities but without this present patch, it is (conceptually) possible to manage a system with capabilities alone and never need to obtain privilege via (set)uid-0. Of course, conceptually isn't quite the same as currently possible since few user applications, certainly not enough to run a viable system, are currently prepared to leverage capabilities to exercise privilege. Further, many applications exist that may never get upgraded in this way, and the kernel will continue to want to support their setuid-0 base privilege needs. Where pure-capability applications evolve and replace setuid-0 binaries, it is desirable that there be a mechanisms by which they can contain their privilege. In addition to leveraging the per-process bounding and inheritable sets, this should include suppressing the privilege of the uid-0 superuser from the process' tree of children. The feature added by this patch can be leveraged to suppress the privilege associated with (set)uid-0. This suppression requires CAP_SETPCAP to initiate, and only immediately affects the 'current' process (it is inherited through fork()/exec()). This reimplementation differs significantly from the historical support for securebits which was system-wide, unwieldy and which has ultimately withered to a dead relic in the source of the modern kernel. With this patch applied a process, that is capable(CAP_SETPCAP), can now drop all legacy privilege (through uid=0) for itself and all subsequently fork()'d/exec()'d children with: prctl(PR_SET_SECUREBITS, 0x2f); This patch represents a no-op unless CONFIG_SECURITY_FILE_CAPABILITIES is enabled at configure time. [akpm@linux-foundation.org: fix uninitialised var warning] [serue@us.ibm.com: capabilities: use cap_task_prctl when !CONFIG_SECURITY] Signed-off-by: Andrew G. Morgan <morgan@kernel.org> Acked-by: Serge Hallyn <serue@us.ibm.com> Reviewed-by: James Morris <jmorris@namei.org> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: Paul Moore <paul.moore@hp.com> Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/prctl.h')
-rw-r--r--include/linux/prctl.h9
1 files changed, 7 insertions, 2 deletions
diff --git a/include/linux/prctl.h b/include/linux/prctl.h
index 5c80b1939636..5ad79198d6f9 100644
--- a/include/linux/prctl.h
+++ b/include/linux/prctl.h
@@ -16,7 +16,8 @@
16# define PR_UNALIGN_NOPRINT 1 /* silently fix up unaligned user accesses */ 16# define PR_UNALIGN_NOPRINT 1 /* silently fix up unaligned user accesses */
17# define PR_UNALIGN_SIGBUS 2 /* generate SIGBUS on unaligned user access */ 17# define PR_UNALIGN_SIGBUS 2 /* generate SIGBUS on unaligned user access */
18 18
19/* Get/set whether or not to drop capabilities on setuid() away from uid 0 */ 19/* Get/set whether or not to drop capabilities on setuid() away from
20 * uid 0 (as per security/commoncap.c) */
20#define PR_GET_KEEPCAPS 7 21#define PR_GET_KEEPCAPS 7
21#define PR_SET_KEEPCAPS 8 22#define PR_SET_KEEPCAPS 8
22 23
@@ -63,7 +64,7 @@
63#define PR_GET_SECCOMP 21 64#define PR_GET_SECCOMP 21
64#define PR_SET_SECCOMP 22 65#define PR_SET_SECCOMP 22
65 66
66/* Get/set the capability bounding set */ 67/* Get/set the capability bounding set (as per security/commoncap.c) */
67#define PR_CAPBSET_READ 23 68#define PR_CAPBSET_READ 23
68#define PR_CAPBSET_DROP 24 69#define PR_CAPBSET_DROP 24
69 70
@@ -73,4 +74,8 @@
73# define PR_TSC_ENABLE 1 /* allow the use of the timestamp counter */ 74# define PR_TSC_ENABLE 1 /* allow the use of the timestamp counter */
74# define PR_TSC_SIGSEGV 2 /* throw a SIGSEGV instead of reading the TSC */ 75# define PR_TSC_SIGSEGV 2 /* throw a SIGSEGV instead of reading the TSC */
75 76
77/* Get/set securebits (as per security/commoncap.c) */
78#define PR_GET_SECUREBITS 27
79#define PR_SET_SECUREBITS 28
80
76#endif /* _LINUX_PRCTL_H */ 81#endif /* _LINUX_PRCTL_H */