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From 25e40facc12017de2c4df5792f6a0a3f7db39896 Mon Sep 17 00:00:00 2001
From: Eugene Syromyatnikov <evgsyr@gmail.com>
Date: Tue, 29 Jan 2019 14:40:11 +0100
Subject: [PATCH 18/27] Use accessors for tcp->s_ent, return a stub struct if
it is NULL
Since code paths are non-trivial, it's an attempt to future-proof
and prevent improper access of tcp->s_ent fields.
* defs.h (struct tcb): Update the description of s_ent field.
(stub_sysent): New declaration.
(tcp_sysent, n_args): New macro functions.
(indirect_ipccall): Use tcp_sysent() instead of tcp->s_ent.
* ipc.c (SYS_FUNC(ipc)): Use n_args() instead of tcp->s_ent->nargs.
* linux/alpha/get_syscall_args.c (get_syscall_args): Likewise.
* linux/bfin/get_syscall_args.c (get_syscall_args): Likewise.
* linux/hppa/get_syscall_args.c (get_syscall_args): Likewise.
* linux/ia64/get_syscall_args.c (get_syscall_args): Likewise.
* linux/microblaze/get_syscall_args.c (get_syscall_args): Likewise.
* linux/mips/get_syscall_args.c (get_syscall_args): Likewise.
* linux/sh/get_syscall_args.c (get_syscall_args): Likewise.
* linux/sh64/get_syscall_args.c (get_syscall_args): Likewise.
* linux/x86_64/get_syscall_args.c (get_syscall_args): Likewise.
* linux/xtensa/get_syscall_args.c (get_syscall_args): Likewise.
* prctl.c (print_prctl_args): Likewise.
* signal.c (SYS_FUNC(sgetmask)): Likewise.
* util.c (printargs, printargs_u, printargs_d): Likewise.
* syscall.c (decode_ipc_subcall, decode_syscall_subcall: Likewise.
(dumpio, tamper_with_syscall_exiting, syscall_entering_decode,
syscall_entering_decode, syscall_entering_trace, syscall_entering_trace,
syscall_exiting_decode, print_syscall_resume, syscall_exiting_trace,
get_syscall_result): Use tcp_sysent() instead of tcp->s_ent.
(stub_sysent): New stub sysent.
(get_scno): Reset scno, s_ent, qual_flg; initialise s->ent from
stub_sysent.
* pathtrace.c (pathtrace_match_set): Use tcp_sysent() instead of
tcp->s_ent.
Co-Authored-by: Dmitry V. Levin <ldv@altlinux.org>
Conflicts:
defs.h
linux/mips/get_syscall_args.c
syscall.c
---
defs.h | 10 ++++++--
ipc.c | 2 +-
linux/alpha/get_syscall_args.c | 2 +-
linux/bfin/get_syscall_args.c | 2 +-
linux/hppa/get_syscall_args.c | 2 +-
linux/ia64/get_syscall_args.c | 2 +-
linux/microblaze/get_syscall_args.c | 2 +-
linux/mips/get_syscall_args.c | 6 ++---
linux/sh/get_syscall_args.c | 2 +-
linux/sh64/get_syscall_args.c | 2 +-
linux/x86_64/get_syscall_args.c | 2 +-
linux/xtensa/get_syscall_args.c | 2 +-
pathtrace.c | 2 +-
prctl.c | 2 +-
signal.c | 4 +--
syscall.c | 49 +++++++++++++++++++++----------------
util.c | 6 ++---
17 files changed, 56 insertions(+), 43 deletions(-)
diff --git a/defs.h b/defs.h
index c7274c8..811bb0d 100644
--- a/defs.h
+++ b/defs.h
@@ -206,7 +206,9 @@ struct tcb {
const char *auxstr; /* Auxiliary info from syscall (see RVAL_STR) */
void *_priv_data; /* Private data for syscall decoding functions */
void (*_free_priv_data)(void *); /* Callback for freeing priv_data */
- const struct_sysent *s_ent; /* sysent[scno] or dummy struct for bad scno */
+ const struct_sysent *s_ent; /* sysent[scno] or a stub struct for bad
+ * scno. Use tcp_sysent() macro for access.
+ */
const struct_sysent *s_prev_ent; /* for "resuming interrupted SYSCALL" msg */
struct inject_opts *inject_vec[SUPPORTED_PERSONALITIES];
struct timespec stime; /* System time usage as of last process wait */
@@ -283,6 +285,10 @@ struct tcb {
#define syscall_delayed(tcp) ((tcp)->flags & TCB_DELAYED)
#define syscall_tampered_nofail(tcp) ((tcp)->flags & TCB_TAMPERED_NO_FAIL)
+extern const struct_sysent stub_sysent;
+#define tcp_sysent(tcp) (tcp->s_ent ?: &stub_sysent)
+#define n_args(tcp) (tcp_sysent(tcp)->nargs)
+
#include "xlat.h"
extern const struct xlat addrfams[];
@@ -352,7 +358,7 @@ extern const struct xlat whence_codes[];
#define IOCTL_NUMBER_HANDLED 1
#define IOCTL_NUMBER_STOP_LOOKUP 010
-#define indirect_ipccall(tcp) (tcp->s_ent->sys_flags & TRACE_INDIRECT_SUBCALL)
+#define indirect_ipccall(tcp) (tcp_sysent(tcp)->sys_flags & TRACE_INDIRECT_SUBCALL)
enum sock_proto {
SOCK_PROTO_UNKNOWN,
diff --git a/ipc.c b/ipc.c
index c35509b..b2b3aa4 100644
--- a/ipc.c
+++ b/ipc.c
@@ -21,7 +21,7 @@ SYS_FUNC(ipc)
printxval_u(ipccalls, call, NULL);
unsigned int i;
- for (i = 1; i < tcp->s_ent->nargs; ++i)
+ for (i = 1; i < n_args(tcp); ++i)
tprintf(", %#" PRI_klx, tcp->u_arg[i]);
return RVAL_DECODED;
diff --git a/linux/alpha/get_syscall_args.c b/linux/alpha/get_syscall_args.c
index be61abf..c28eb62 100644
--- a/linux/alpha/get_syscall_args.c
+++ b/linux/alpha/get_syscall_args.c
@@ -4,7 +4,7 @@ get_syscall_args(struct tcb *tcp)
{
unsigned int i;
- for (i = 0; i < tcp->s_ent->nargs; ++i)
+ for (i = 0; i < n_args(tcp); ++i)
if (upeek(tcp, REG_A0+i, &tcp->u_arg[i]) < 0)
return -1;
return 1;
diff --git a/linux/bfin/get_syscall_args.c b/linux/bfin/get_syscall_args.c
index 506d3a9..bebaf03 100644
--- a/linux/bfin/get_syscall_args.c
+++ b/linux/bfin/get_syscall_args.c
@@ -7,7 +7,7 @@ get_syscall_args(struct tcb *tcp)
};
unsigned int i;
- for (i = 0; i < tcp->s_ent->nargs; ++i)
+ for (i = 0; i < n_args(tcp); ++i)
if (upeek(tcp, argreg[i], &tcp->u_arg[i]) < 0)
return -1;
return 1;
diff --git a/linux/hppa/get_syscall_args.c b/linux/hppa/get_syscall_args.c
index aa938f5..70f2a24 100644
--- a/linux/hppa/get_syscall_args.c
+++ b/linux/hppa/get_syscall_args.c
@@ -4,7 +4,7 @@ get_syscall_args(struct tcb *tcp)
{
unsigned int i;
- for (i = 0; i < tcp->s_ent->nargs; ++i)
+ for (i = 0; i < n_args(tcp); ++i)
if (upeek(tcp, PT_GR26-4*i, &tcp->u_arg[i]) < 0)
return -1;
return 1;
diff --git a/linux/ia64/get_syscall_args.c b/linux/ia64/get_syscall_args.c
index ad73c54..eeeb59c 100644
--- a/linux/ia64/get_syscall_args.c
+++ b/linux/ia64/get_syscall_args.c
@@ -11,7 +11,7 @@ get_syscall_args(struct tcb *tcp)
unsigned long *out0 = ia64_rse_skip_regs(rbs_end, -sof + sol);
unsigned int i;
- for (i = 0; i < tcp->s_ent->nargs; ++i) {
+ for (i = 0; i < n_args(tcp); ++i) {
if (umove(tcp,
(unsigned long) ia64_rse_skip_regs(out0, i),
&tcp->u_arg[i]) < 0) {
diff --git a/linux/microblaze/get_syscall_args.c b/linux/microblaze/get_syscall_args.c
index 1a3a48f..0e249e3 100644
--- a/linux/microblaze/get_syscall_args.c
+++ b/linux/microblaze/get_syscall_args.c
@@ -4,7 +4,7 @@ get_syscall_args(struct tcb *tcp)
{
unsigned int i;
- for (i = 0; i < tcp->s_ent->nargs; ++i)
+ for (i = 0; i < n_args(tcp); ++i)
if (upeek(tcp, (5 + i) * 4, &tcp->u_arg[i]) < 0)
return -1;
return 1;
diff --git a/linux/mips/get_syscall_args.c b/linux/mips/get_syscall_args.c
index 3c9160e..0ff5136 100644
--- a/linux/mips/get_syscall_args.c
+++ b/linux/mips/get_syscall_args.c
@@ -14,16 +14,16 @@ get_syscall_args(struct tcb *tcp)
tcp->u_arg[1] = mips_REG_A1;
tcp->u_arg[2] = mips_REG_A2;
tcp->u_arg[3] = mips_REG_A3;
- if (tcp->s_ent->nargs > 4
+ if (n_args(tcp) > 4
&& umoven(tcp, mips_REG_SP + 4 * sizeof(tcp->u_arg[0]),
- (tcp->s_ent->nargs - 4) * sizeof(tcp->u_arg[0]),
+ (n_args(tcp) - 4) * sizeof(tcp->u_arg[0]),
&tcp->u_arg[4]) < 0) {
/*
* Let's proceed with the first 4 arguments
* instead of reporting the failure.
*/
memset(&tcp->u_arg[4], 0,
- (tcp->s_ent->nargs - 4) * sizeof(tcp->u_arg[0]));
+ (n_args(tcp) - 4) * sizeof(tcp->u_arg[0]));
}
#else
# error unsupported mips abi
diff --git a/linux/sh/get_syscall_args.c b/linux/sh/get_syscall_args.c
index b4ee1dd..02593b0 100644
--- a/linux/sh/get_syscall_args.c
+++ b/linux/sh/get_syscall_args.c
@@ -12,7 +12,7 @@ get_syscall_args(struct tcb *tcp)
};
unsigned int i;
- for (i = 0; i < tcp->s_ent->nargs; ++i)
+ for (i = 0; i < n_args(tcp); ++i)
if (upeek(tcp, syscall_regs[i], &tcp->u_arg[i]) < 0)
return -1;
return 1;
diff --git a/linux/sh64/get_syscall_args.c b/linux/sh64/get_syscall_args.c
index e35c350..241ff09 100644
--- a/linux/sh64/get_syscall_args.c
+++ b/linux/sh64/get_syscall_args.c
@@ -6,7 +6,7 @@ get_syscall_args(struct tcb *tcp)
static const int syscall_regs[MAX_ARGS] = { 2, 3, 4, 5, 6, 7 };
unsigned int i;
- for (i = 0; i < tcp->s_ent->nargs; ++i)
+ for (i = 0; i < n_args(tcp); ++i)
if (upeek(tcp, REG_GENERAL(syscall_regs[i]),
&tcp->u_arg[i]) < 0)
return -1;
diff --git a/linux/x86_64/get_syscall_args.c b/linux/x86_64/get_syscall_args.c
index f285ac3..8ee8ebd 100644
--- a/linux/x86_64/get_syscall_args.c
+++ b/linux/x86_64/get_syscall_args.c
@@ -4,7 +4,7 @@ get_syscall_args(struct tcb *tcp)
{
if (x86_io.iov_len != sizeof(i386_regs)) {
/* x86-64 or x32 ABI */
- if (tcp->s_ent->sys_flags & COMPAT_SYSCALL_TYPES) {
+ if (tcp_sysent(tcp)->sys_flags & COMPAT_SYSCALL_TYPES) {
/*
* X32 compat syscall: zero-extend from 32 bits.
* Use truncate_klong_to_current_wordsize(tcp->u_arg[N])
diff --git a/linux/xtensa/get_syscall_args.c b/linux/xtensa/get_syscall_args.c
index 2a20cdb..6903221 100644
--- a/linux/xtensa/get_syscall_args.c
+++ b/linux/xtensa/get_syscall_args.c
@@ -13,7 +13,7 @@ get_syscall_args(struct tcb *tcp)
};
unsigned int i;
- for (i = 0; i < tcp->s_ent->nargs; ++i)
+ for (i = 0; i < n_args(tcp); ++i)
if (upeek(tcp, xtensaregs[i], &tcp->u_arg[i]) < 0)
return -1;
return 1;
diff --git a/pathtrace.c b/pathtrace.c
index 2cd12e6..5493028 100644
--- a/pathtrace.c
+++ b/pathtrace.c
@@ -167,7 +167,7 @@ pathtrace_match_set(struct tcb *tcp, struct path_set *set)
{
const struct_sysent *s;
- s = tcp->s_ent;
+ s = tcp_sysent(tcp);
if (!(s->sys_flags & (TRACE_FILE | TRACE_DESC | TRACE_NETWORK)))
return false;
diff --git a/prctl.c b/prctl.c
index 5830f11..c31ea60 100644
--- a/prctl.c
+++ b/prctl.c
@@ -61,7 +61,7 @@ print_prctl_args(struct tcb *tcp, const unsigned int first)
{
unsigned int i;
- for (i = first; i < tcp->s_ent->nargs; ++i)
+ for (i = first; i < n_args(tcp); ++i)
tprintf(", %#" PRI_klx, tcp->u_arg[i]);
}
diff --git a/signal.c b/signal.c
index 17a3f79..e59a76d 100644
--- a/signal.c
+++ b/signal.c
@@ -383,10 +383,10 @@ SYS_FUNC(sgetmask)
SYS_FUNC(sigsuspend)
{
#ifdef MIPS
- print_sigset_addr_len(tcp, tcp->u_arg[tcp->s_ent->nargs - 1],
+ print_sigset_addr_len(tcp, tcp->u_arg[n_args(tcp) - 1],
current_wordsize);
#else
- tprint_old_sigmask_val("", tcp->u_arg[tcp->s_ent->nargs - 1]);
+ tprint_old_sigmask_val("", tcp->u_arg[n_args(tcp) - 1]);
#endif
return RVAL_DECODED;
diff --git a/syscall.c b/syscall.c
index 33f6dcd..40fcedb 100644
--- a/syscall.c
+++ b/syscall.c
@@ -339,7 +339,7 @@ decode_ipc_subcall(struct tcb *tcp)
tcp->qual_flg = qual_flags(tcp->scno);
tcp->s_ent = &sysent[tcp->scno];
- const unsigned int n = tcp->s_ent->nargs;
+ const unsigned int n = n_args(tcp);
unsigned int i;
for (i = 0; i < n; i++)
tcp->u_arg[i] = tcp->u_arg[i + 1];
@@ -363,7 +363,7 @@ decode_syscall_subcall(struct tcb *tcp)
* and sync_file_range) requires additional code,
* see linux/mips/get_syscall_args.c
*/
- if (tcp->s_ent->nargs == MAX_ARGS) {
+ if (n_args(tcp) == MAX_ARGS) {
if (umoven(tcp,
mips_REG_SP + MAX_ARGS * sizeof(tcp->u_arg[0]),
sizeof(tcp->u_arg[0]),
@@ -382,7 +382,7 @@ dumpio(struct tcb *tcp)
return;
if (is_number_in_set(fd, write_set)) {
- switch (tcp->s_ent->sen) {
+ switch (tcp_sysent(tcp)->sen) {
case SEN_write:
case SEN_pwrite:
case SEN_send:
@@ -409,7 +409,7 @@ dumpio(struct tcb *tcp)
return;
if (is_number_in_set(fd, read_set)) {
- switch (tcp->s_ent->sen) {
+ switch (tcp_sysent(tcp)->sen) {
case SEN_read:
case SEN_pread:
case SEN_recv:
@@ -573,7 +573,7 @@ tamper_with_syscall_exiting(struct tcb *tcp)
if (update_tcb) {
tcp->u_error = 0;
- get_error(tcp, !(tcp->s_ent->sys_flags & SYSCALL_NEVER_FAILS));
+ get_error(tcp, !(tcp_sysent(tcp)->sys_flags & SYSCALL_NEVER_FAILS));
}
return 0;
@@ -593,10 +593,9 @@ syscall_entering_decode(struct tcb *tcp)
int res = get_scno(tcp);
if (res == 0)
return res;
- int scno_good = res;
if (res != 1 || (res = get_syscall_args(tcp)) != 1) {
printleader(tcp);
- tprintf("%s(", scno_good == 1 ? tcp->s_ent->sys_name : "????");
+ tprintf("%s(", tcp_sysent(tcp)->sys_name);
/*
* " <unavailable>" will be added later by the code which
* detects ptrace errors.
@@ -608,7 +607,7 @@ syscall_entering_decode(struct tcb *tcp)
|| defined SYS_socket_subcall \
|| defined SYS_syscall_subcall
for (;;) {
- switch (tcp->s_ent->sen) {
+ switch (tcp_sysent(tcp)->sen) {
# ifdef SYS_ipc_subcall
case SEN_ipc:
decode_ipc_subcall(tcp);
@@ -622,7 +621,7 @@ syscall_entering_decode(struct tcb *tcp)
# ifdef SYS_syscall_subcall
case SEN_syscall:
decode_syscall_subcall(tcp);
- if (tcp->s_ent->sen != SEN_syscall)
+ if (tcp_sysent(tcp)->sen != SEN_syscall)
continue;
break;
# endif
@@ -642,7 +641,7 @@ syscall_entering_trace(struct tcb *tcp, unsigned int *sig)
tcp->qual_flg &= ~QUAL_INJECT;
}
- switch (tcp->s_ent->sen) {
+ switch (tcp_sysent(tcp)->sen) {
case SEN_execve:
case SEN_execveat:
#if defined SPARC || defined SPARC64
@@ -672,14 +671,14 @@ syscall_entering_trace(struct tcb *tcp, unsigned int *sig)
#ifdef ENABLE_STACKTRACE
if (stack_trace_enabled) {
- if (tcp->s_ent->sys_flags & STACKTRACE_CAPTURE_ON_ENTER)
+ if (tcp_sysent(tcp)->sys_flags & STACKTRACE_CAPTURE_ON_ENTER)
unwind_tcb_capture(tcp);
}
#endif
printleader(tcp);
- tprintf("%s(", tcp->s_ent->sys_name);
- int res = raw(tcp) ? printargs(tcp) : tcp->s_ent->sys_func(tcp);
+ tprintf("%s(", tcp_sysent(tcp)->sys_name);
+ int res = raw(tcp) ? printargs(tcp) : tcp_sysent(tcp)->sys_func(tcp);
fflush(tcp->outf);
return res;
}
@@ -709,7 +708,7 @@ syscall_exiting_decode(struct tcb *tcp, struct timespec *pts)
if ((Tflag || cflag) && !(filtered(tcp) || hide_log(tcp)))
clock_gettime(CLOCK_MONOTONIC, pts);
- if (tcp->s_ent->sys_flags & MEMORY_MAPPING_CHANGE)
+ if (tcp_sysent(tcp)->sys_flags & MEMORY_MAPPING_CHANGE)
mmap_notify_report(tcp);
if (filtered(tcp) || hide_log(tcp))
@@ -738,7 +737,7 @@ print_syscall_resume(struct tcb *tcp)
|| (tcp->flags & TCB_REPRINT)) {
tcp->flags &= ~TCB_REPRINT;
printleader(tcp);
- tprintf("<... %s resumed>", tcp->s_ent->sys_name);
+ tprintf("<... %s resumed>", tcp_sysent(tcp)->sys_name);
}
}
@@ -786,7 +785,7 @@ syscall_exiting_trace(struct tcb *tcp, struct timespec *ts, int res)
if (tcp->sys_func_rval & RVAL_DECODED)
sys_res = tcp->sys_func_rval;
else
- sys_res = tcp->s_ent->sys_func(tcp);
+ sys_res = tcp_sysent(tcp)->sys_func(tcp);
}
tprints(") ");
@@ -1175,6 +1174,13 @@ free_sysent_buf(void *ptr)
free(ptr);
}
+const struct_sysent stub_sysent = {
+ .nargs = MAX_ARGS,
+ .sen = SEN_printargs,
+ .sys_func = printargs,
+ .sys_name = "????",
+};
+
/*
* Returns:
* 0: "ignore this ptrace stop", syscall_entering_decode() should return a "bail
@@ -1186,6 +1192,10 @@ free_sysent_buf(void *ptr)
int
get_scno(struct tcb *tcp)
{
+ tcp->scno = -1;
+ tcp->s_ent = NULL;
+ tcp->qual_flg = QUAL_RAW | DEFAULT_QUAL_FLAGS;
+
if (get_regs(tcp) < 0)
return -1;
@@ -1202,14 +1212,11 @@ get_scno(struct tcb *tcp)
struct sysent_buf *s = xcalloc(1, sizeof(*s));
s->tcp = tcp;
- s->ent.nargs = MAX_ARGS;
- s->ent.sen = SEN_printargs;
- s->ent.sys_func = printargs;
+ s->ent = stub_sysent;
s->ent.sys_name = s->buf;
xsprintf(s->buf, "syscall_%#" PRI_klx, shuffle_scno(tcp->scno));
tcp->s_ent = &s->ent;
- tcp->qual_flg = QUAL_RAW | DEFAULT_QUAL_FLAGS;
set_tcb_priv_data(tcp, s, free_sysent_buf);
@@ -1246,7 +1253,7 @@ get_syscall_result(struct tcb *tcp)
return -1;
tcp->u_error = 0;
get_error(tcp,
- (!(tcp->s_ent->sys_flags & SYSCALL_NEVER_FAILS)
+ (!(tcp_sysent(tcp)->sys_flags & SYSCALL_NEVER_FAILS)
|| syscall_tampered(tcp))
&& !syscall_tampered_nofail(tcp));
diff --git a/util.c b/util.c
index aefedee..b841c0f 100644
--- a/util.c
+++ b/util.c
@@ -1161,7 +1161,7 @@ print_array_ex(struct tcb *const tcp,
int
printargs(struct tcb *tcp)
{
- const int n = tcp->s_ent->nargs;
+ const int n = n_args(tcp);
int i;
for (i = 0; i < n; ++i)
tprintf("%s%#" PRI_klx, i ? ", " : "", tcp->u_arg[i]);
@@ -1171,7 +1171,7 @@ printargs(struct tcb *tcp)
int
printargs_u(struct tcb *tcp)
{
- const int n = tcp->s_ent->nargs;
+ const int n = n_args(tcp);
int i;
for (i = 0; i < n; ++i)
tprintf("%s%u", i ? ", " : "",
@@ -1182,7 +1182,7 @@ printargs_u(struct tcb *tcp)
int
printargs_d(struct tcb *tcp)
{
- const int n = tcp->s_ent->nargs;
+ const int n = n_args(tcp);
int i;
for (i = 0; i < n; ++i)
tprintf("%s%d", i ? ", " : "",
--
2.1.4
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