/**
* Replace current @tracee's syscall with an older and compatible one
* whenever it's required, i.e. when the syscall is supported by the
* kernel as specified by @config->virtual_release but it isn't
* supported by the actual kernel.
*/
static int handle_sysenter_end(Tracee *tracee, Config *config)
{
/* Note: syscalls like "openat" can be replaced by "open" since PRoot
* has canonicalized "fd + path" into "path". */
switch (get_sysnum(tracee, ORIGINAL)) {
case PR_accept4: {
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,28),
.new_sysarg_num = PR_accept,
.shifts = NONE
};
modify_syscall(tracee, config, &modif);
return 0;
}
case PR_dup3: {
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,27),
.new_sysarg_num = PR_dup2,
.shifts = NONE
};
/* "If oldfd equals newfd, then dup3() fails with the
* error EINVAL" -- man dup3 */
if (peek_reg(tracee, CURRENT, SYSARG_1) == peek_reg(tracee, CURRENT, SYSARG_2))
return -EINVAL;
modify_syscall(tracee, config, &modif);
return 0;
}
case PR_epoll_create1: {
bool modified;
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,27),
.new_sysarg_num = PR_epoll_create,
.shifts = NONE
};
/* "the size argument is ignored, but must be greater
* than zero" -- man epoll_create */
modified = modify_syscall(tracee, config, &modif);
if (modified)
poke_reg(tracee, SYSARG_1, 1);
return 0;
}
case PR_epoll_pwait: {
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,19),
.new_sysarg_num = PR_epoll_wait,
.shifts = NONE
};
modify_syscall(tracee, config, &modif);
return 0;
}
case PR_eventfd2: {
bool modified;
word_t flags;
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,27),
.new_sysarg_num = PR_eventfd,
.shifts = NONE
};
modified = modify_syscall(tracee, config, &modif);
if (modified) {
/* EFD_SEMAPHORE can't be emulated with eventfd. */
flags = peek_reg(tracee, CURRENT, SYSARG_2);
if ((flags & EFD_SEMAPHORE) != 0)
return -EINVAL;
}
return 0;
}
case PR_faccessat: {
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,16),
.new_sysarg_num = PR_access,
.shifts = { [0] = {
.sysarg = SYSARG_2,
.nb_args = 2,
.offset = -1 }
}
};
modify_syscall(tracee, config, &modif);
return 0;
}
case PR_fchmodat: {
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,16),
.new_sysarg_num = PR_chmod,
.shifts = { [0] = {
.sysarg = SYSARG_2,
.nb_args = 2,
.offset = -1 }
}
};
modify_syscall(tracee, config, &modif);
return 0;
}
case PR_fchownat: {
word_t flags;
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,16),
.shifts = { [0] = {
.sysarg = SYSARG_2,
.nb_args = 3,
.offset = -1 }
}
};
flags = peek_reg(tracee, CURRENT, SYSARG_5);
modif.new_sysarg_num = ((flags & AT_SYMLINK_NOFOLLOW) != 0
? PR_lchown
: PR_chown);
modify_syscall(tracee, config, &modif);
return 0;
}
case PR_fcntl: {
word_t command;
if (!needs_kompat(config, KERNEL_VERSION(2,6,24)))
return 0;
command = peek_reg(tracee, ORIGINAL, SYSARG_2);
if (command == F_DUPFD_CLOEXEC)
poke_reg(tracee, SYSARG_2, F_DUPFD);
return 0;
}
case PR_newfstatat:
case PR_fstatat64: {
word_t flags;
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,16),
.shifts = { [0] = {
.sysarg = SYSARG_2,
.nb_args = 2,
.offset = -1 }
}
};
flags = peek_reg(tracee, CURRENT, SYSARG_4);
if ((flags & ~AT_SYMLINK_NOFOLLOW) != 0)
return -EINVAL; /* Exposed by LTP. */
#if defined(ARCH_X86_64)
if ((flags & AT_SYMLINK_NOFOLLOW) != 0)
modif.new_sysarg_num = (get_abi(tracee) != ABI_2 ? PR_lstat : PR_lstat64);
else
modif.new_sysarg_num = (get_abi(tracee) != ABI_2 ? PR_stat : PR_stat64);
#else
if ((flags & AT_SYMLINK_NOFOLLOW) != 0)
modif.new_sysarg_num = PR_lstat64;
else
modif.new_sysarg_num = PR_stat64;
#endif
modify_syscall(tracee, config, &modif);
return 0;
}
case PR_futex: {
word_t operation;
static bool warned = false;
if (!needs_kompat(config, KERNEL_VERSION(2,6,22)) || config->actual_release == 0)
return 0;
operation = peek_reg(tracee, CURRENT, SYSARG_2);
if ((operation & FUTEX_PRIVATE_FLAG) == 0)
return 0;
if (!warned) {
warned = true;
note(tracee, WARNING, USER,
"kompat: this kernel doesn't support private futexes "
"and PRoot can't emulate them. Expect some troubles...");
}
poke_reg(tracee, SYSARG_2, operation & ~FUTEX_PRIVATE_FLAG);
return 0;
}
case PR_futimesat: {
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,16),
.new_sysarg_num = PR_utimes,
.shifts = { [0] = {
.sysarg = SYSARG_2,
.nb_args = 2,
.offset = -1 }
}
};
modify_syscall(tracee, config, &modif);
return 0;
}
case PR_inotify_init1: {
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,27),
.new_sysarg_num = PR_inotify_init,
.shifts = NONE
};
modify_syscall(tracee, config, &modif);
return 0;
}
case PR_linkat: {
word_t flags;
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,16),
.new_sysarg_num = PR_link,
.shifts = { [0] = {
.sysarg = SYSARG_2,
.nb_args = 1,
.offset = -1 },
[1] = {
.sysarg = SYSARG_4,
.nb_args = 1,
.offset = -2 }
}
};
flags = peek_reg(tracee, CURRENT, SYSARG_5);
if ((flags & ~AT_SYMLINK_FOLLOW) != 0)
return -EINVAL; /* Exposed by LTP. */
modify_syscall(tracee, config, &modif);
return 0;
}
case PR_mkdirat: {
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,16),
.new_sysarg_num = PR_mkdir,
.shifts = { [0] = {
.sysarg = SYSARG_2,
.nb_args = 2,
.offset = -1 }
}
};
modify_syscall(tracee, config, &modif);
return 0;
}
/**
* Replace current @tracee's syscall with an older and compatible one
* whenever it's required, i.e. when the syscall is supported by the
* kernel as specified by @config->release but it isn't supported by
* the actual kernel.
*/
static void handle_sysenter_end(Tracee *tracee, Config *config)
{
bool modified;
/* Note: syscalls like "openat" can be replaced by "open" since PRoot
* has canonicalized "fd + path" into "path". */
switch (get_sysnum(tracee, ORIGINAL)) {
case PR_accept4: {
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,28),
.new_sysarg_num = PR_accept,
.shifts = {{0}}
};
modify_syscall(tracee, config, &modif);
return;
}
case PR_dup3: {
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,27),
.new_sysarg_num = PR_dup2,
.shifts = {{0}}
};
modify_syscall(tracee, config, &modif);
return;
}
case PR_epoll_create1: {
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,27),
.new_sysarg_num = PR_epoll_create,
.shifts = {{0}}
};
modified = modify_syscall(tracee, config, &modif);
if (modified)
poke_reg(tracee, SYSARG_1, 0); /* Force "size" to 0. */
return;
}
case PR_epoll_pwait: {
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,19),
.new_sysarg_num = PR_epoll_wait,
.shifts = {{0}}
};
modified = modify_syscall(tracee, config, &modif);
if (modified)
poke_reg(tracee, SYSARG_5, 0); /* Force "sigmask" to 0. */
return;
}
case PR_eventfd2: {
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,27),
.new_sysarg_num = PR_eventfd,
.shifts = {{0}}
};
modified = modify_syscall(tracee, config, &modif);
if (modified)
poke_reg(tracee, SYSARG_2, 0); /* Force "flags" to 0. */
return;
}
case PR_faccessat: {
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,16),
.new_sysarg_num = PR_access,
.shifts = { [0] = {
.sysarg = SYSARG_2,
.nb_args = 2,
.offset = -1 }
}
};
modified = modify_syscall(tracee, config, &modif);
if (modified)
poke_reg(tracee, SYSARG_4, 0); /* Force "flags" to 0. */
return;
}
case PR_fchmodat: {
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,16),
.new_sysarg_num = PR_chmod,
.shifts = { [0] = {
.sysarg = SYSARG_2,
.nb_args = 2,
.offset = -1 }
}
};
modified = modify_syscall(tracee, config, &modif);
if (modified)
poke_reg(tracee, SYSARG_4, 0); /* Force "flags" to 0. */
return;
}
case PR_fchownat: {
word_t flags;
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,16),
.shifts = { [0] = {
.sysarg = SYSARG_2,
.nb_args = 3,
.offset = -1 }
}
};
flags = peek_reg(tracee, CURRENT, SYSARG_5);
modif.new_sysarg_num = ((flags & AT_SYMLINK_NOFOLLOW) != 0
? PR_lchown
: PR_chown);
modified = modify_syscall(tracee, config, &modif);
if (modified)
poke_reg(tracee, SYSARG_5, 0); /* Force "flags" to 0. */
return;
}
case PR_newfstatat:
case PR_fstatat64: {
word_t flags;
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,16),
.shifts = { [0] = {
.sysarg = SYSARG_2,
.nb_args = 2,
.offset = -1 }
}
};
flags = peek_reg(tracee, CURRENT, SYSARG_4);
#if defined(ARCH_X86_64)
if ((flags & AT_SYMLINK_NOFOLLOW) != 0)
modif.new_sysarg_num = (get_abi(tracee) != ABI_2 ? PR_lstat : PR_lstat64);
else
modif.new_sysarg_num = (get_abi(tracee) != ABI_2 ? PR_stat : PR_stat64);
#else
if ((flags & AT_SYMLINK_NOFOLLOW) != 0)
modif.new_sysarg_num = PR_lstat64;
else
modif.new_sysarg_num = PR_stat64;
#endif
modified = modify_syscall(tracee, config, &modif);
if (modified)
poke_reg(tracee, SYSARG_4, 0); /* Force "flags" to 0. */
return;
}
case PR_futimesat: {
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,16),
.new_sysarg_num = PR_utimes,
.shifts = { [0] = {
.sysarg = SYSARG_2,
.nb_args = 2,
.offset = -1 }
}
};
modify_syscall(tracee, config, &modif);
return;
}
case PR_inotify_init1: {
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,27),
.new_sysarg_num = PR_inotify_init,
.shifts = {{0}}
};
modified = modify_syscall(tracee, config, &modif);
if (modified)
poke_reg(tracee, SYSARG_1, 0); /* Force "flags" to 0. */
return;
}
case PR_linkat: {
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,16),
.new_sysarg_num = PR_link,
.shifts = { [0] = {
.sysarg = SYSARG_2,
.nb_args = 1,
.offset = -1 },
[1] = {
.sysarg = SYSARG_4,
.nb_args = 1,
.offset = -2 }
}
};
modified = modify_syscall(tracee, config, &modif);
if (modified)
poke_reg(tracee, SYSARG_5, 0); /* Force "flags" to 0. */
return;
}
case PR_mkdirat: {
Modif modif = {
.expected_release = KERNEL_VERSION(2,6,16),
.new_sysarg_num = PR_mkdir,
.shifts = { [0] = {
.sysarg = SYSARG_2,
.nb_args = 2,
.offset = -1 }
}
};
modify_syscall(tracee, config, &modif);
return;
}