From: Steven Rostedt <[email protected]> Some of the system calls that read a fixed length of memory from the user space address are not arrays but strings. Take a bit away from the nb_args field in the syscall meta data to use as a flag to denote that the system call's user_arg_size is being used as a string. The nb_args should never be more than 6, so 7 bits is plenty to hold that number. When the user_arg_is_str flag that, when set, will display the data array from the user space address as a string and not an array.
This will allow the output to look like this: sys_sethostname(name: 0x5584310eb2a0 "debian", len: 6) Signed-off-by: Steven Rostedt (Google) <[email protected]> --- include/trace/syscall.h | 4 +++- kernel/trace/trace_syscalls.c | 22 +++++++++++++++++++--- 2 files changed, 22 insertions(+), 4 deletions(-) diff --git a/include/trace/syscall.h b/include/trace/syscall.h index 9413c139da66..0dd7f2b33431 100644 --- a/include/trace/syscall.h +++ b/include/trace/syscall.h @@ -16,6 +16,7 @@ * @name: name of the syscall * @syscall_nr: number of the syscall * @nb_args: number of parameters it takes + * @user_arg_is_str: set if the arg for @user_arg_size is a string * @user_arg_size: holds @arg that has size of the user space to read * @user_mask: mask of @args that will read user space * @types: list of types as strings @@ -27,7 +28,8 @@ struct syscall_metadata { const char *name; int syscall_nr; - u8 nb_args; + u8 nb_args:7; + u8 user_arg_is_str:1; s8 user_arg_size; short user_mask; const char **types; diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c index 6b9eb5a8e156..5a318c1592b9 100644 --- a/kernel/trace/trace_syscalls.c +++ b/kernel/trace/trace_syscalls.c @@ -184,7 +184,7 @@ print_syscall_enter(struct trace_iterator *iter, int flags, ptr = (void *)ent + (val & 0xffff); len = val >> 16; - if (entry->user_arg_size < 0) { + if (entry->user_arg_size < 0 || entry->user_arg_is_str) { trace_seq_printf(s, " \"%.*s\"", len, ptr); continue; } @@ -249,6 +249,7 @@ print_syscall_exit(struct trace_iterator *iter, int flags, static int __init __set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len) { + bool is_string = entry->user_arg_is_str; int i; int pos = 0; @@ -266,7 +267,7 @@ __set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len) continue; /* Add the format for the user space string or array */ - if (entry->user_arg_size < 0) + if (entry->user_arg_size < 0 || is_string) pos += snprintf(buf + pos, LEN_OR_ZERO, " \\\"%%s\\\""); else pos += snprintf(buf + pos, LEN_OR_ZERO, " (%%s)"); @@ -279,7 +280,7 @@ __set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len) if (!(BIT(i) & entry->user_mask)) continue; /* The user space data for arg has name __<arg>_val */ - if (entry->user_arg_size < 0) { + if (entry->user_arg_size < 0 || is_string) { pos += snprintf(buf + pos, LEN_OR_ZERO, ", __get_str(__%s_val)", entry->args[i]); } else { @@ -781,6 +782,21 @@ static void check_faultable_syscall(struct trace_event_call *call, int nr) sys_data->user_mask = BIT(1); sys_data->user_arg_size = 2; break; + /* user arg 0 with size arg at 1 as string */ + case __NR_setdomainname: + case __NR_sethostname: + sys_data->user_mask = BIT(0); + sys_data->user_arg_size = 1; + sys_data->user_arg_is_str = 1; + break; +#if defined(__ARCH_WANT_TIME32_SYSCALLS) || __BITS_PER_LONG != 32 + /* user arg 4 with size arg at 3 as string */ + case __NR_kexec_file_load: + sys_data->user_mask = BIT(4); + sys_data->user_arg_size = 3; + sys_data->user_arg_is_str = 1; + break; +#endif /* user arg at position 0 */ case __NR_access: case __NR_acct: -- 2.51.0
