From d0420c83f39f79afb82010c2d2cafd150eef651b Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 2 Sep 2009 09:14:16 +0100 Subject: KEYS: Extend TIF_NOTIFY_RESUME to (almost) all architectures [try #6] Implement TIF_NOTIFY_RESUME for most of those architectures in which isn't yet available, and, whilst we're at it, have it call the appropriate tracehook. After this patch, blackfin, m68k* and xtensa still lack support and need alteration of assembly code to make it work. Resume notification can then be used (by a later patch) to install a new session keyring on the parent of a process. Signed-off-by: David Howells Acked-by: Russell King cc: linux-arch@vger.kernel.org Signed-off-by: James Morris --- arch/arm/include/asm/thread_info.h | 3 +++ arch/arm/kernel/entry-common.S | 2 +- arch/arm/kernel/signal.c | 5 +++++ 3 files changed, 9 insertions(+), 1 deletion(-) (limited to 'arch/arm') diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h index 73394e50cbc..d3a39b1e6c0 100644 --- a/arch/arm/include/asm/thread_info.h +++ b/arch/arm/include/asm/thread_info.h @@ -130,11 +130,13 @@ extern void vfp_sync_state(struct thread_info *thread); * TIF_SYSCALL_TRACE - syscall trace active * TIF_SIGPENDING - signal pending * TIF_NEED_RESCHED - rescheduling necessary + * TIF_NOTIFY_RESUME - callback before returning to user * TIF_USEDFPU - FPU was used by this task this quantum (SMP) * TIF_POLLING_NRFLAG - true if poll_idle() is polling TIF_NEED_RESCHED */ #define TIF_SIGPENDING 0 #define TIF_NEED_RESCHED 1 +#define TIF_NOTIFY_RESUME 2 /* callback before returning to user */ #define TIF_SYSCALL_TRACE 8 #define TIF_POLLING_NRFLAG 16 #define TIF_USING_IWMMXT 17 @@ -143,6 +145,7 @@ extern void vfp_sync_state(struct thread_info *thread); #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) +#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE) #define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG) #define _TIF_USING_IWMMXT (1 << TIF_USING_IWMMXT) diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index 8c3de1a350b..7813ab782fd 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -51,7 +51,7 @@ fast_work_pending: work_pending: tst r1, #_TIF_NEED_RESCHED bne work_resched - tst r1, #_TIF_SIGPENDING + tst r1, #_TIF_SIGPENDING|_TIF_NOTIFY_RESUME beq no_work_pending mov r0, sp @ 'regs' mov r2, why @ 'syscall' diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c index f6bc5d44278..13dec276927 100644 --- a/arch/arm/kernel/signal.c +++ b/arch/arm/kernel/signal.c @@ -707,4 +707,9 @@ do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall) { if (thread_flags & _TIF_SIGPENDING) do_signal(¤t->blocked, regs, syscall); + + if (thread_flags & _TIF_NOTIFY_RESUME) { + clear_thread_flag(TIF_NOTIFY_RESUME); + tracehook_notify_resume(regs); + } } -- cgit v1.2.3 From ee18d64c1f632043a02e6f5ba5e045bb26a5465f Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 2 Sep 2009 09:14:21 +0100 Subject: KEYS: Add a keyctl to install a process's session keyring on its parent [try #6] Add a keyctl to install a process's session keyring onto its parent. This replaces the parent's session keyring. Because the COW credential code does not permit one process to change another process's credentials directly, the change is deferred until userspace next starts executing again. Normally this will be after a wait*() syscall. To support this, three new security hooks have been provided: cred_alloc_blank() to allocate unset security creds, cred_transfer() to fill in the blank security creds and key_session_to_parent() - which asks the LSM if the process may replace its parent's session keyring. The replacement may only happen if the process has the same ownership details as its parent, and the process has LINK permission on the session keyring, and the session keyring is owned by the process, and the LSM permits it. Note that this requires alteration to each architecture's notify_resume path. This has been done for all arches barring blackfin, m68k* and xtensa, all of which need assembly alteration to support TIF_NOTIFY_RESUME. This allows the replacement to be performed at the point the parent process resumes userspace execution. This allows the userspace AFS pioctl emulation to fully emulate newpag() and the VIOCSETTOK and VIOCSETTOK2 pioctls, all of which require the ability to alter the parent process's PAG membership. However, since kAFS doesn't use PAGs per se, but rather dumps the keys into the session keyring, the session keyring of the parent must be replaced if, for example, VIOCSETTOK is passed the newpag flag. This can be tested with the following program: #include #include #include #define KEYCTL_SESSION_TO_PARENT 18 #define OSERROR(X, S) do { if ((long)(X) == -1) { perror(S); exit(1); } } while(0) int main(int argc, char **argv) { key_serial_t keyring, key; long ret; keyring = keyctl_join_session_keyring(argv[1]); OSERROR(keyring, "keyctl_join_session_keyring"); key = add_key("user", "a", "b", 1, keyring); OSERROR(key, "add_key"); ret = keyctl(KEYCTL_SESSION_TO_PARENT); OSERROR(ret, "KEYCTL_SESSION_TO_PARENT"); return 0; } Compiled and linked with -lkeyutils, you should see something like: [dhowells@andromeda ~]$ keyctl show Session Keyring -3 --alswrv 4043 4043 keyring: _ses 355907932 --alswrv 4043 -1 \_ keyring: _uid.4043 [dhowells@andromeda ~]$ /tmp/newpag [dhowells@andromeda ~]$ keyctl show Session Keyring -3 --alswrv 4043 4043 keyring: _ses 1055658746 --alswrv 4043 4043 \_ user: a [dhowells@andromeda ~]$ /tmp/newpag hello [dhowells@andromeda ~]$ keyctl show Session Keyring -3 --alswrv 4043 4043 keyring: hello 340417692 --alswrv 4043 4043 \_ user: a Where the test program creates a new session keyring, sticks a user key named 'a' into it and then installs it on its parent. Signed-off-by: David Howells Signed-off-by: James Morris --- arch/arm/kernel/signal.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/arm') diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c index 13dec276927..ea4ad3a43c8 100644 --- a/arch/arm/kernel/signal.c +++ b/arch/arm/kernel/signal.c @@ -711,5 +711,7 @@ do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall) if (thread_flags & _TIF_NOTIFY_RESUME) { clear_thread_flag(TIF_NOTIFY_RESUME); tracehook_notify_resume(regs); + if (current->replacement_session_keyring) + key_replace_session_keyring(); } } -- cgit v1.2.3 From 733e5e4b4eb1bc1e27acbe092200154051171426 Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 9 Sep 2009 08:30:21 +0100 Subject: KEYS: Add missing linux/tracehook.h #inclusions Add #inclusions of linux/tracehook.h to those arch files that had the tracehook call for TIF_NOTIFY_RESUME added when support for that flag was added to that arch. Signed-off-by: David Howells Signed-off-by: James Morris --- arch/arm/kernel/signal.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/arm') diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c index ea4ad3a43c8..b76fe06d92e 100644 --- a/arch/arm/kernel/signal.c +++ b/arch/arm/kernel/signal.c @@ -12,6 +12,7 @@ #include #include #include +#include #include #include -- cgit v1.2.3