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Use PTRACE_GETREGS/PTRACE_SETREGS on platforms that support it.

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This has a better chance of working on things like user-mode Linux.
This commit is contained in:
Todd C. Miller
2022-04-29 13:09:03 -06:00
parent 4010d06ed0
commit b75a8be34d
1 changed files with 49 additions and 18 deletions
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67
src/exec_ptrace.c
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@@ -62,9 +62,9 @@
* For example code, see tools/testing/selftests/seccomp/seccomp_bpf.c
*
* The structs and registers vary among the different platforms.
* We define user_regs_struct as the struct to use for the
* PTRACE_GETREGSET/PTRACE_SETREGSET command and define accessor
* macros to get/set the struct members.
* We define user_regs_struct as the struct to use for gettings
* and setting the general registers and define accessor
* macros to get/set the individual struct members.
*
* The value of SECCOMP_AUDIT_ARCH is used when matching the architecture
* in the seccomp(2) filter.
@@ -182,6 +182,48 @@
# error "Do not know how to find your architecture's registers"
#endif
/*
* Use PTRACE_GETREGS and PTRACE_SETREGS where available.
* Otherwise, use PTRACE_GETREGSET and PTRACE_SETREGSET.
*/
#if defined(__x86_64__) || defined(__i386__)
static int
ptrace_getregs(int pid, struct user_pt_regs *regs)
{
debug_decl(ptrace_getregs, SUDO_DEBUG_EXEC);
debug_return_int(ptrace(PTRACE_GETREGS, pid, NULL, regs));
}
static int
ptrace_setregs(int pid, struct user_pt_regs *regs)
{
debug_decl(ptrace_setregs, SUDO_DEBUG_EXEC);
debug_return_int(ptrace(PTRACE_SETREGS, pid, NULL, regs));
}
#else
static int
ptrace_getregs(int pid, struct user_pt_regs *regs)
{
struct iovec iov;
debug_decl(ptrace_getregs, SUDO_DEBUG_EXEC);
iov.iov_base = regs;
iov.iov_len = sizeof(*regs);
debug_return_int(ptrace(PTRACE_GETREGSET, pid, (long)NT_PRSTATUS, &iov));
}
static int
ptrace_setregs(int pid, struct user_pt_regs *regs)
{
struct iovec iov;
debug_decl(ptrace_setregs, SUDO_DEBUG_EXEC);
iov.iov_base = regs;
iov.iov_len = sizeof(*regs);
debug_return_int(ptrace(PTRACE_SETREGSET, pid, (long)NT_PRSTATUS, &iov));
}
#endif /* __x86_64__ || __i386__ */
/*
* Read the string at addr and store in buf.
* Returns the number of bytes stored, including the NUL.
@@ -438,18 +480,14 @@ bad:
static bool
ptrace_fail_syscall(pid_t pid, struct user_pt_regs *regs, int ecode)
{
struct iovec iov;
sigset_t chldmask;
bool ret = false;
int status;
debug_decl(ptrace_fail_syscall, SUDO_DEBUG_EXEC);
iov.iov_base = regs;
iov.iov_len = sizeof(*regs);
/* Cause the syscall to fail by changing its number to -1. */
reg_syscall(regs) |= 0xffffffff;
if (ptrace(PTRACE_SETREGSET, pid, (long)NT_PRSTATUS, &iov) == -1) {
if (ptrace_setregs(pid, regs) == -1) {
sudo_warn(U_("unable to set registers for process %d"), (int)pid);
debug_return_bool(false);
}
@@ -474,7 +512,7 @@ ptrace_fail_syscall(pid_t pid, struct user_pt_regs *regs, int ecode)
goto done;
}
reg_retval(regs) = -ecode;
if (ptrace(PTRACE_SETREGSET, pid, (long)NT_PRSTATUS, &iov) == -1) {
if (ptrace_setregs(pid, regs) == -1) {
sudo_warn(U_("unable to set registers for process %d"), (int)pid);
goto done;
}
@@ -613,7 +651,6 @@ ptrace_intercept_execve(pid_t pid, struct intercept_closure *closure)
int argc, envc, syscallno;
struct user_pt_regs regs;
char cwd[PATH_MAX];
struct iovec iov;
bool ret = false;
debug_decl(ptrace_intercept_execve, SUDO_DEBUG_UTIL);
@@ -624,10 +661,7 @@ ptrace_intercept_execve(pid_t pid, struct intercept_closure *closure)
}
/* Get the registers. */
/* XXX - for amd64 and i386 use PTRACE_GETREGS/PTRACE_SETREGS instead. */
iov.iov_base = &regs;
iov.iov_len = sizeof(regs);
if (ptrace(PTRACE_GETREGSET, pid, (long)NT_PRSTATUS, &iov) == -1) {
if (ptrace_getregs(pid, &regs) == -1) {
sudo_warn(U_("unable to get registers for process %d"), (int)pid);
debug_return_bool(false);
}
@@ -695,7 +729,6 @@ ptrace_intercept_execve(pid_t pid, struct intercept_closure *closure)
*/
long sp = reg_sp(&regs) - 128;
long new_argv, strtab;
struct iovec iov;
size_t len;
/* Calculate the amount of space required for argv + strings. */
@@ -736,10 +769,8 @@ ptrace_intercept_execve(pid_t pid, struct intercept_closure *closure)
}
/* Update argv address in the tracee to our new value. */
iov.iov_base = &regs;
iov.iov_len = sizeof(regs);
reg_arg2(&regs) = new_argv;
if (ptrace(PTRACE_SETREGSET, pid, (long)NT_PRSTATUS, &iov) == -1) {
if (ptrace_setregs(pid, &regs) == -1) {
sudo_warn(U_("unable to set registers for process %d"),
(int)pid);
goto done;