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Use the entire word in ptrace_get_vec_len() and ptrace_read_vec().

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For compat binaries, use the upper 32-bits as the next word instead
of calling ptrace(2) to get it.  This reduces the number of ptrace(2)
calls when reading argv and envp for compat binaries.
This commit is contained in:
Todd C. Miller
2022-05-09 10:09:30 -06:00
parent c9a481506d
commit f82aa334cc
2 changed files with 49 additions and 26 deletions
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72
src/exec_ptrace.c
View File

@@ -261,11 +261,9 @@ ptrace_getregs(int pid, struct sudo_ptrace_regs *regs, bool compat)
if (compat) { if (compat) {
regs->compat = true; regs->compat = true;
regs->wordsize = sizeof(int); regs->wordsize = sizeof(int);
regs->addrmask = (unsigned int)-1;
} else { } else {
regs->compat = false; regs->compat = false;
regs->wordsize = sizeof(long); regs->wordsize = sizeof(long);
regs->addrmask = (unsigned long)-1;
} }
debug_return_bool(true); debug_return_bool(true);
@@ -315,8 +313,8 @@ ptrace_read_string(pid_t pid, long addr, char *buf, size_t bufsize)
for (;;) { for (;;) {
word = ptrace(PTRACE_PEEKDATA, pid, addr, NULL); word = ptrace(PTRACE_PEEKDATA, pid, addr, NULL);
if (word == -1) { if (word == -1) {
sudo_warn("ptrace(PTRACE_PEEKDATA, %d, 0x%lx, NULL)", sudo_warn("%s: ptrace(PTRACE_PEEKDATA, %d, 0x%lx, NULL)",
(int)pid, addr); __func__, (int)pid, addr);
debug_return_ssize_t(-1); debug_return_ssize_t(-1);
} }
@@ -345,6 +343,7 @@ static size_t
ptrace_read_vec(pid_t pid, struct sudo_ptrace_regs *regs, long addr, ptrace_read_vec(pid_t pid, struct sudo_ptrace_regs *regs, long addr,
char **vec, char *buf, size_t bufsize) char **vec, char *buf, size_t bufsize)
{ {
unsigned long word, next_word = -1;
char *buf0 = buf; char *buf0 = buf;
int len = 0; int len = 0;
size_t slen; size_t slen;
@@ -352,12 +351,22 @@ ptrace_read_vec(pid_t pid, struct sudo_ptrace_regs *regs, long addr,
/* Fill in vector. */ /* Fill in vector. */
for (;;) { for (;;) {
long word = ptrace(PTRACE_PEEKDATA, pid, addr, NULL); if (next_word == (unsigned long)-1) {
word &= regs->addrmask; word = ptrace(PTRACE_PEEKDATA, pid, addr, NULL);
if (regs->compat) {
/* Stash the next compat word in next_word. */
next_word = word >> 32;
word &= 0xffffffffU;
}
} else {
/* Use the stashed value of the next word. */
word = next_word;
next_word = (unsigned long)-1;
}
switch (word) { switch (word) {
case -1: case -1:
sudo_warn("ptrace(PTRACE_PEEKDATA, %d, 0x%lx, NULL)", sudo_warn("%s: ptrace(PTRACE_PEEKDATA, %d, 0x%lx, NULL)",
(int)pid, addr); __func__, (int)pid, addr);
goto bad; goto bad;
case 0: case 0:
vec[len] = NULL; vec[len] = NULL;
@@ -387,16 +396,27 @@ bad:
static int static int
ptrace_get_vec_len(pid_t pid, struct sudo_ptrace_regs *regs, long addr) ptrace_get_vec_len(pid_t pid, struct sudo_ptrace_regs *regs, long addr)
{ {
unsigned long word, next_word = -1;
int len = 0; int len = 0;
debug_decl(ptrace_get_vec_len, SUDO_DEBUG_EXEC); debug_decl(ptrace_get_vec_len, SUDO_DEBUG_EXEC);
for (;;) { for (;;) {
long word = ptrace(PTRACE_PEEKDATA, pid, addr, NULL); if (next_word == (unsigned long)-1) {
word &= regs->addrmask; word = ptrace(PTRACE_PEEKDATA, pid, addr, NULL);
if (regs->compat) {
/* Stash the next compat word in next_word. */
next_word = word >> 32;
word &= 0xffffffffU;
}
} else {
/* Use the stashed value of the next word. */
word = next_word;
next_word = (unsigned long)-1;
}
switch (word) { switch (word) {
case -1: case -1:
sudo_warn("ptrace(PTRACE_PEEKDATA, %d, 0x%lx, NULL)", sudo_warn("%s: ptrace(PTRACE_PEEKDATA, %d, 0x%lx, NULL)",
(int)pid, addr); __func__, (int)pid, addr);
debug_return_int(-1); debug_return_int(-1);
case 0: case 0:
debug_return_int(len); debug_return_int(len);
@@ -438,8 +458,8 @@ ptrace_write_string(pid_t pid, long addr, const char *str)
u.buf[i] = *str++; u.buf[i] = *str++;
} }
if (ptrace(PTRACE_POKEDATA, pid, addr, u.word) == -1) { if (ptrace(PTRACE_POKEDATA, pid, addr, u.word) == -1) {
sudo_warn("ptrace(PTRACE_POKEDATA, %d, 0x%lx, %.*s)", sudo_warn("%s: ptrace(PTRACE_POKEDATA, %d, 0x%lx, %.*s)",
(int)pid, addr, (int)sizeof(u.buf), u.buf); __func__, (int)pid, addr, (int)sizeof(u.buf), u.buf);
debug_return_size_t(-1); debug_return_size_t(-1);
} }
if (*str == '\0') if (*str == '\0')
@@ -714,8 +734,8 @@ exec_ptrace_seize(pid_t child)
* possible to run sudo inside a sudo shell with intercept enabled. * possible to run sudo inside a sudo shell with intercept enabled.
*/ */
if (errno != EPERM) { if (errno != EPERM) {
sudo_warn("ptrace(PTRACE_SEIZE, %d, NULL, 0x%lx)", (int)child, sudo_warn("%s: ptrace(PTRACE_SEIZE, %d, NULL, 0x%lx)",
ptrace_opts); __func__, (int)child, ptrace_opts);
goto done; goto done;
} }
sudo_debug_printf(SUDO_DEBUG_WARN, sudo_debug_printf(SUDO_DEBUG_WARN,
@@ -726,7 +746,7 @@ exec_ptrace_seize(pid_t child)
/* The child is suspended waiting for SIGUSR1, wake it up. */ /* The child is suspended waiting for SIGUSR1, wake it up. */
if (kill(child, SIGUSR1) == -1) { if (kill(child, SIGUSR1) == -1) {
sudo_warn("kill(%d, SIGUSR1)", child); sudo_warn("kill(%d, SIGUSR1)", (int)child);
goto done; goto done;
} }
if (!ret) if (!ret)
@@ -746,7 +766,8 @@ exec_ptrace_seize(pid_t child)
goto done; goto done;
} }
if (ptrace(PTRACE_CONT, child, NULL, (long)SIGUSR1) == -1) { if (ptrace(PTRACE_CONT, child, NULL, (long)SIGUSR1) == -1) {
sudo_warn("ptrace(PTRACE_CONT, %d, NULL, SIGUSR1)", (int)child); sudo_warn("%s: ptrace(PTRACE_CONT, %d, NULL, SIGUSR1)",
__func__, (int)child);
goto done; goto done;
} }
@@ -936,8 +957,9 @@ ptrace_intercept_execve(pid_t pid, struct intercept_closure *closure)
for (i = 0; i < argc; i++) { for (i = 0; i < argc; i++) {
/* Store string address as new argv[i]. */ /* Store string address as new argv[i]. */
if (ptrace(PTRACE_POKEDATA, pid, sp, strtab) == -1) { if (ptrace(PTRACE_POKEDATA, pid, sp, strtab) == -1) {
sudo_warn("ptrace(PTRACE_POKEDATA, %d, 0x%lx, 0x%lx)", sudo_warn(
(int)pid, sp, strtab); "%s: ptrace(PTRACE_POKEDATA, %d, 0x%lx, 0x%lx)",
__func__, (int)pid, sp, strtab);
goto done; goto done;
} }
sp += regs.wordsize; sp += regs.wordsize;
@@ -949,8 +971,8 @@ ptrace_intercept_execve(pid_t pid, struct intercept_closure *closure)
strtab += len; strtab += len;
} }
if (ptrace(PTRACE_POKEDATA, pid, sp, NULL) == -1) { if (ptrace(PTRACE_POKEDATA, pid, sp, NULL) == -1) {
sudo_warn("ptrace(PTRACE_POKEDATA, %d, 0x%lx, NULL)", sudo_warn("%s: ptrace(PTRACE_POKEDATA, %d, 0x%lx, NULL)",
(int)pid, sp); __func__, (int)pid, sp);
goto done; goto done;
} }
} }
@@ -1056,11 +1078,13 @@ exec_ptrace_handled(pid_t pid, int status, void *intercept)
* until SIGCONT is received (simulate SIGSTOP, etc). * until SIGCONT is received (simulate SIGSTOP, etc).
*/ */
if (ptrace(PTRACE_LISTEN, pid, NULL, 0L) == -1) if (ptrace(PTRACE_LISTEN, pid, NULL, 0L) == -1)
sudo_warn("ptrace(PTRACE_LISTEN, %d, NULL, %d)", (int)pid, stopsig); sudo_warn("%s: ptrace(PTRACE_LISTEN, %d, NULL, %d)",
__func__, (int)pid, stopsig);
} else { } else {
/* Restart child. */ /* Restart child. */
if (ptrace(PTRACE_CONT, pid, NULL, signo) == -1) if (ptrace(PTRACE_CONT, pid, NULL, signo) == -1)
sudo_warn("ptrace(PTRACE_CONT, %d, NULL, %ld)", (int)pid, signo); sudo_warn("%s: ptrace(PTRACE_CONT, %d, NULL, %ld)",
__func__, (int)pid, signo);
} }
debug_return_bool(signo == 0); debug_return_bool(signo == 0);

3
src/exec_ptrace.h
View File

@@ -231,8 +231,7 @@ struct sudo_ptrace_regs {
struct compat_user_pt_regs compat; struct compat_user_pt_regs compat;
#endif #endif
} u; } u;
unsigned long wordsize; unsigned int wordsize;
unsigned long addrmask;
bool compat; bool compat;
}; };