Andrei Vagin <avagin@xxxxxxxxx> reported: > Accoding to the man page, the user should not set si_signo, it has to be set > by kernel. > > $ man 2 rt_sigqueueinfo > > The uinfo argument specifies the data to accompany the signal. This > argument is a pointer to a structure of type siginfo_t, described in > sigaction(2) (and defined by including <sigaction.h>). The caller > should set the following fields in this structure: > > si_code > This must be one of the SI_* codes in the Linux kernel source > file include/asm-generic/siginfo.h, with the restriction that > the code must be negative (i.e., cannot be SI_USER, which is > used by the kernel to indicate a signal sent by kill(2)) and > cannot (since Linux 2.6.39) be SI_TKILL (which is used by the > kernel to indicate a signal sent using tgkill(2)). > > si_pid This should be set to a process ID, typically the process ID of > the sender. > > si_uid This should be set to a user ID, typically the real user ID of > the sender. > > si_value > This field contains the user data to accompany the signal. For > more information, see the description of the last (union sigval) > argument of sigqueue(3). > > Internally, the kernel sets the si_signo field to the value specified > in sig, so that the receiver of the signal can also obtain the signal > number via that field. > > On Tue, Sep 25, 2018 at 07:19:02PM +0200, Eric W. Biederman wrote: >> >> If there is some application that calls sigqueueinfo directly that has >> a problem with this added sanity check we can revisit this when we see >> what kind of crazy that application is doing. > > > I already know two "applications" ;) > > https://github.com/torvalds/linux/blob/master/tools/testing/selftests/ptrace/peeksiginfo.c > https://github.com/checkpoint-restore/criu/blob/master/test/zdtm/static/sigpending.c > > Disclaimer: I'm the author of both of them. Looking at the kernel code the historical behavior has alwasy been to prefer the signal number passed in by the kernel. So sigh. Implmenet __copy_siginfo_from_user and __copy_siginfo_from_user32 to take that signal number and prefer it. The user of ptrace will still use copy_siginfo_from_user and copy_siginfo_from_user32 as they do not and never have had a signal number there. Luckily this change has never made it farther than linux-next. Fixes: e75dc036c445 ("signal: Fail sigqueueinfo if si_signo != sig") Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> --- Andrei can you verify this fixes your programs? Thank you very much, Eric kernel/signal.c | 141 ++++++++++++++++++++++++++++-------------------- 1 file changed, 84 insertions(+), 57 deletions(-) diff --git a/kernel/signal.c b/kernel/signal.c index 1c2dd117fee0..2bffc5a50183 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2925,11 +2925,10 @@ int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from) return 0; } -int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from) +static int post_copy_siginfo_from_user(kernel_siginfo_t *info, + const siginfo_t __user *from) { - if (copy_from_user(to, from, sizeof(struct kernel_siginfo))) - return -EFAULT; - if (unlikely(!known_siginfo_layout(to->si_signo, to->si_code))) { + if (unlikely(!known_siginfo_layout(info->si_signo, info->si_code))) { char __user *expansion = si_expansion(from); char buf[SI_EXPANSION_SIZE]; int i; @@ -2949,6 +2948,22 @@ int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from) return 0; } +static int __copy_siginfo_from_user(int signo, kernel_siginfo_t *to, + const siginfo_t __user *from) +{ + if (copy_from_user(to, from, sizeof(struct kernel_siginfo))) + return -EFAULT; + to->si_signo = signo; + return post_copy_siginfo_from_user(to, from); +} + +int copy_siginfo_from_user(kernel_siginfo_t *to, const siginfo_t __user *from) +{ + if (copy_from_user(to, from, sizeof(struct kernel_siginfo))) + return -EFAULT; + return post_copy_siginfo_from_user(to, from); +} + #ifdef CONFIG_COMPAT int copy_siginfo_to_user32(struct compat_siginfo __user *to, const struct kernel_siginfo *from) @@ -3041,88 +3056,106 @@ int __copy_siginfo_to_user32(struct compat_siginfo __user *to, return 0; } -int copy_siginfo_from_user32(struct kernel_siginfo *to, - const struct compat_siginfo __user *ufrom) +static int post_copy_siginfo_from_user32(kernel_siginfo_t *to, + const struct compat_siginfo *from) { - struct compat_siginfo from; - - if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo))) - return -EFAULT; - clear_siginfo(to); - to->si_signo = from.si_signo; - to->si_errno = from.si_errno; - to->si_code = from.si_code; - switch(siginfo_layout(from.si_signo, from.si_code)) { + to->si_signo = from->si_signo; + to->si_errno = from->si_errno; + to->si_code = from->si_code; + switch(siginfo_layout(from->si_signo, from->si_code)) { case SIL_KILL: - to->si_pid = from.si_pid; - to->si_uid = from.si_uid; + to->si_pid = from->si_pid; + to->si_uid = from->si_uid; break; case SIL_TIMER: - to->si_tid = from.si_tid; - to->si_overrun = from.si_overrun; - to->si_int = from.si_int; + to->si_tid = from->si_tid; + to->si_overrun = from->si_overrun; + to->si_int = from->si_int; break; case SIL_POLL: - to->si_band = from.si_band; - to->si_fd = from.si_fd; + to->si_band = from->si_band; + to->si_fd = from->si_fd; break; case SIL_FAULT: - to->si_addr = compat_ptr(from.si_addr); + to->si_addr = compat_ptr(from->si_addr); #ifdef __ARCH_SI_TRAPNO - to->si_trapno = from.si_trapno; + to->si_trapno = from->si_trapno; #endif break; case SIL_FAULT_MCEERR: - to->si_addr = compat_ptr(from.si_addr); + to->si_addr = compat_ptr(from->si_addr); #ifdef __ARCH_SI_TRAPNO - to->si_trapno = from.si_trapno; + to->si_trapno = from->si_trapno; #endif - to->si_addr_lsb = from.si_addr_lsb; + to->si_addr_lsb = from->si_addr_lsb; break; case SIL_FAULT_BNDERR: - to->si_addr = compat_ptr(from.si_addr); + to->si_addr = compat_ptr(from->si_addr); #ifdef __ARCH_SI_TRAPNO - to->si_trapno = from.si_trapno; + to->si_trapno = from->si_trapno; #endif - to->si_lower = compat_ptr(from.si_lower); - to->si_upper = compat_ptr(from.si_upper); + to->si_lower = compat_ptr(from->si_lower); + to->si_upper = compat_ptr(from->si_upper); break; case SIL_FAULT_PKUERR: - to->si_addr = compat_ptr(from.si_addr); + to->si_addr = compat_ptr(from->si_addr); #ifdef __ARCH_SI_TRAPNO - to->si_trapno = from.si_trapno; + to->si_trapno = from->si_trapno; #endif - to->si_pkey = from.si_pkey; + to->si_pkey = from->si_pkey; break; case SIL_CHLD: - to->si_pid = from.si_pid; - to->si_uid = from.si_uid; - to->si_status = from.si_status; + to->si_pid = from->si_pid; + to->si_uid = from->si_uid; + to->si_status = from->si_status; #ifdef CONFIG_X86_X32_ABI if (in_x32_syscall()) { - to->si_utime = from._sifields._sigchld_x32._utime; - to->si_stime = from._sifields._sigchld_x32._stime; + to->si_utime = from->_sifields._sigchld_x32._utime; + to->si_stime = from->_sifields._sigchld_x32._stime; } else #endif { - to->si_utime = from.si_utime; - to->si_stime = from.si_stime; + to->si_utime = from->si_utime; + to->si_stime = from->si_stime; } break; case SIL_RT: - to->si_pid = from.si_pid; - to->si_uid = from.si_uid; - to->si_int = from.si_int; + to->si_pid = from->si_pid; + to->si_uid = from->si_uid; + to->si_int = from->si_int; break; case SIL_SYS: - to->si_call_addr = compat_ptr(from.si_call_addr); - to->si_syscall = from.si_syscall; - to->si_arch = from.si_arch; + to->si_call_addr = compat_ptr(from->si_call_addr); + to->si_syscall = from->si_syscall; + to->si_arch = from->si_arch; break; } return 0; } + +static int __copy_siginfo_from_user32(int signo, struct kernel_siginfo *to, + const struct compat_siginfo __user *ufrom) +{ + struct compat_siginfo from; + + if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo))) + return -EFAULT; + + from.si_signo = signo; + return post_copy_siginfo_from_user32(to, &from); +} + +int copy_siginfo_from_user32(struct kernel_siginfo *to, + const struct compat_siginfo __user *ufrom) +{ + struct compat_siginfo from; + + if (copy_from_user(&from, ufrom, sizeof(struct compat_siginfo))) + return -EFAULT; + + return post_copy_siginfo_from_user32(to, &from); +} #endif /* CONFIG_COMPAT */ /** @@ -3359,9 +3392,6 @@ static int do_rt_sigqueueinfo(pid_t pid, int sig, kernel_siginfo_t *info) (task_pid_vnr(current) != pid)) return -EPERM; - if (info->si_signo != sig) - return -EINVAL; - /* POSIX.1b doesn't mention process groups. */ return kill_proc_info(sig, info, pid); } @@ -3376,7 +3406,7 @@ SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig, siginfo_t __user *, uinfo) { kernel_siginfo_t info; - int ret = copy_siginfo_from_user(&info, uinfo); + int ret = __copy_siginfo_from_user(sig, &info, uinfo); if (unlikely(ret)) return ret; return do_rt_sigqueueinfo(pid, sig, &info); @@ -3389,7 +3419,7 @@ COMPAT_SYSCALL_DEFINE3(rt_sigqueueinfo, struct compat_siginfo __user *, uinfo) { kernel_siginfo_t info; - int ret = copy_siginfo_from_user32(&info, uinfo); + int ret = __copy_siginfo_from_user32(sig, &info, uinfo); if (unlikely(ret)) return ret; return do_rt_sigqueueinfo(pid, sig, &info); @@ -3409,9 +3439,6 @@ static int do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, kernel_siginfo_t (task_pid_vnr(current) != pid)) return -EPERM; - if (info->si_signo != sig) - return -EINVAL; - return do_send_specific(tgid, pid, sig, info); } @@ -3419,7 +3446,7 @@ SYSCALL_DEFINE4(rt_tgsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig, siginfo_t __user *, uinfo) { kernel_siginfo_t info; - int ret = copy_siginfo_from_user(&info, uinfo); + int ret = __copy_siginfo_from_user(sig, &info, uinfo); if (unlikely(ret)) return ret; return do_rt_tgsigqueueinfo(tgid, pid, sig, &info); @@ -3433,7 +3460,7 @@ COMPAT_SYSCALL_DEFINE4(rt_tgsigqueueinfo, struct compat_siginfo __user *, uinfo) { kernel_siginfo_t info; - int ret = copy_siginfo_from_user32(&info, uinfo); + int ret = __copy_siginfo_from_user32(sig, &info, uinfo); if (unlikely(ret)) return ret; return do_rt_tgsigqueueinfo(tgid, pid, sig, &info);
