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author | Linus Torvalds <torvalds@linux-foundation.org> | 2012-12-16 23:40:50 (GMT) |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-12-16 23:40:50 (GMT) |
commit | 2a74dbb9a86e8102dcd07d284135b4530a84826e (patch) | |
tree | a54403e312b6062dfb57bd904ba8b8ce3b11e720 /arch | |
parent | 770b6cb4d21fb3e3df2a7a51e186a3c14db1ec30 (diff) | |
parent | e93072374112db9dc86635934ee761249be28370 (diff) | |
download | linux-2a74dbb9a86e8102dcd07d284135b4530a84826e.tar.xz |
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
Pull security subsystem updates from James Morris:
"A quiet cycle for the security subsystem with just a few maintenance
updates."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
Smack: create a sysfs mount point for smackfs
Smack: use select not depends in Kconfig
Yama: remove locking from delete path
Yama: add RCU to drop read locking
drivers/char/tpm: remove tasklet and cleanup
KEYS: Use keyring_alloc() to create special keyrings
KEYS: Reduce initial permissions on keys
KEYS: Make the session and process keyrings per-thread
seccomp: Make syscall skipping and nr changes more consistent
key: Fix resource leak
keys: Fix unreachable code
KEYS: Add payload preparsing opportunity prior to key instantiate or update
Diffstat (limited to 'arch')
-rw-r--r-- | arch/x86/kernel/vsyscall_64.c | 110 |
1 files changed, 59 insertions, 51 deletions
diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c index 3a3e8c9..9a907a6 100644 --- a/arch/x86/kernel/vsyscall_64.c +++ b/arch/x86/kernel/vsyscall_64.c @@ -145,19 +145,6 @@ static int addr_to_vsyscall_nr(unsigned long addr) return nr; } -#ifdef CONFIG_SECCOMP -static int vsyscall_seccomp(struct task_struct *tsk, int syscall_nr) -{ - if (!seccomp_mode(&tsk->seccomp)) - return 0; - task_pt_regs(tsk)->orig_ax = syscall_nr; - task_pt_regs(tsk)->ax = syscall_nr; - return __secure_computing(syscall_nr); -} -#else -#define vsyscall_seccomp(_tsk, _nr) 0 -#endif - static bool write_ok_or_segv(unsigned long ptr, size_t size) { /* @@ -190,10 +177,9 @@ bool emulate_vsyscall(struct pt_regs *regs, unsigned long address) { struct task_struct *tsk; unsigned long caller; - int vsyscall_nr; + int vsyscall_nr, syscall_nr, tmp; int prev_sig_on_uaccess_error; long ret; - int skip; /* * No point in checking CS -- the only way to get here is a user mode @@ -225,56 +211,84 @@ bool emulate_vsyscall(struct pt_regs *regs, unsigned long address) } tsk = current; - /* - * With a real vsyscall, page faults cause SIGSEGV. We want to - * preserve that behavior to make writing exploits harder. - */ - prev_sig_on_uaccess_error = current_thread_info()->sig_on_uaccess_error; - current_thread_info()->sig_on_uaccess_error = 1; /* + * Check for access_ok violations and find the syscall nr. + * * NULL is a valid user pointer (in the access_ok sense) on 32-bit and * 64-bit, so we don't need to special-case it here. For all the * vsyscalls, NULL means "don't write anything" not "write it at * address 0". */ - ret = -EFAULT; - skip = 0; switch (vsyscall_nr) { case 0: - skip = vsyscall_seccomp(tsk, __NR_gettimeofday); - if (skip) - break; - if (!write_ok_or_segv(regs->di, sizeof(struct timeval)) || - !write_ok_or_segv(regs->si, sizeof(struct timezone))) - break; + !write_ok_or_segv(regs->si, sizeof(struct timezone))) { + ret = -EFAULT; + goto check_fault; + } + + syscall_nr = __NR_gettimeofday; + break; + + case 1: + if (!write_ok_or_segv(regs->di, sizeof(time_t))) { + ret = -EFAULT; + goto check_fault; + } + + syscall_nr = __NR_time; + break; + + case 2: + if (!write_ok_or_segv(regs->di, sizeof(unsigned)) || + !write_ok_or_segv(regs->si, sizeof(unsigned))) { + ret = -EFAULT; + goto check_fault; + } + + syscall_nr = __NR_getcpu; + break; + } + + /* + * Handle seccomp. regs->ip must be the original value. + * See seccomp_send_sigsys and Documentation/prctl/seccomp_filter.txt. + * + * We could optimize the seccomp disabled case, but performance + * here doesn't matter. + */ + regs->orig_ax = syscall_nr; + regs->ax = -ENOSYS; + tmp = secure_computing(syscall_nr); + if ((!tmp && regs->orig_ax != syscall_nr) || regs->ip != address) { + warn_bad_vsyscall(KERN_DEBUG, regs, + "seccomp tried to change syscall nr or ip"); + do_exit(SIGSYS); + } + if (tmp) + goto do_ret; /* skip requested */ + /* + * With a real vsyscall, page faults cause SIGSEGV. We want to + * preserve that behavior to make writing exploits harder. + */ + prev_sig_on_uaccess_error = current_thread_info()->sig_on_uaccess_error; + current_thread_info()->sig_on_uaccess_error = 1; + + ret = -EFAULT; + switch (vsyscall_nr) { + case 0: ret = sys_gettimeofday( (struct timeval __user *)regs->di, (struct timezone __user *)regs->si); break; case 1: - skip = vsyscall_seccomp(tsk, __NR_time); - if (skip) - break; - - if (!write_ok_or_segv(regs->di, sizeof(time_t))) - break; - ret = sys_time((time_t __user *)regs->di); break; case 2: - skip = vsyscall_seccomp(tsk, __NR_getcpu); - if (skip) - break; - - if (!write_ok_or_segv(regs->di, sizeof(unsigned)) || - !write_ok_or_segv(regs->si, sizeof(unsigned))) - break; - ret = sys_getcpu((unsigned __user *)regs->di, (unsigned __user *)regs->si, NULL); @@ -283,12 +297,7 @@ bool emulate_vsyscall(struct pt_regs *regs, unsigned long address) current_thread_info()->sig_on_uaccess_error = prev_sig_on_uaccess_error; - if (skip) { - if ((long)regs->ax <= 0L) /* seccomp errno emulation */ - goto do_ret; - goto done; /* seccomp trace/trap */ - } - +check_fault: if (ret == -EFAULT) { /* Bad news -- userspace fed a bad pointer to a vsyscall. */ warn_bad_vsyscall(KERN_INFO, regs, @@ -311,7 +320,6 @@ do_ret: /* Emulate a ret instruction. */ regs->ip = caller; regs->sp += 8; -done: return true; sigsegv: |