1 /*
2 * Copyright (c) 1991, 1992 Paul Kranenburg <pk@cs.few.eur.nl>
3 * Copyright (c) 1993 Branko Lankester <branko@hacktic.nl>
4 * Copyright (c) 1993, 1994, 1995, 1996 Rick Sladkey <jrs@world.std.com>
5 * Copyright (c) 1996-1999 Wichert Akkerman <wichert@cistron.nl>
6 * Copyright (c) 2005-2007 Roland McGrath <roland@redhat.com>
7 * Copyright (c) 2006-2007 Ulrich Drepper <drepper@redhat.com>
8 * Copyright (c) 2009-2013 Denys Vlasenko <dvlasenk@redhat.com>
9 * Copyright (c) 2005-2015 Dmitry V. Levin <ldv@strace.io>
10 * Copyright (c) 2014-2022 The strace developers.
11 * All rights reserved.
12 *
13 * SPDX-License-Identifier: LGPL-2.1-or-later
14 */
15
16 #include "defs.h"
17 #include "xstring.h"
18 #include "kernel_fcntl.h"
19 #include "number_set.h"
20 #include <linux/openat2.h>
21 #include <linux/fcntl.h>
22
23 #include "xlat/open_access_modes.h"
24 #include "xlat/open_mode_flags.h"
25 #include "xlat/open_resolve_flags.h"
26
27 /* The fd is an "int", so when decoding x86 on x86_64, we need to force sign
28 * extension to get the right value. We do this by declaring fd as int here.
29 */
30 void
31 print_dirfd(struct tcb *tcp, int fd)
32 {
33 if (fd == AT_FDCWD) {
34 print_xlat_d(AT_FDCWD);
35
36 if (!is_number_in_set(DECODE_FD_PATH, decode_fd_set))
37 goto done;
38
39 int proc_pid = get_proc_pid(tcp->pid);
40 if (!proc_pid)
41 goto done;
42
43 static const char cwd_path[] = "/proc/%u/cwd";
44 char linkpath[sizeof(cwd_path) + sizeof(int) * 3];
45 xsprintf(linkpath, cwd_path, proc_pid);
46
47 char buf[PATH_MAX];
48 ssize_t n = readlink(linkpath, buf, sizeof(buf));
49 if ((size_t) n >= sizeof(buf))
50 goto done;
51
52 tprint_associated_info_begin();
53 print_quoted_string_ex(buf, n,
54 QUOTE_OMIT_LEADING_TRAILING_QUOTES,
55 "<>");
56 tprint_associated_info_end();
57 done: ;
58 } else {
59 printfd(tcp, fd);
60 }
61 #ifdef ENABLE_SECONTEXT
62 tcp->last_dirfd = fd;
63 #endif
64 }
65
66 /*
67 * low bits of the open(2) flags define access mode,
68 * other bits are real flags.
69 */
70 static const char *
71 sprint_open_modes64(uint64_t flags)
72 {
73 static char outstr[sizeof("flags O_ACCMODE")];
74 char *p;
75 char sep;
76 const char *str;
77
78 sep = ' ';
79 p = stpcpy(outstr, "flags");
80 str = xlookup(open_access_modes, flags & 3);
81 if (str) {
82 *p++ = sep;
83 p = stpcpy(p, str);
84 flags &= ~3;
85 if (!flags)
86 return outstr;
87 sep = '|';
88 }
89 *p = '\0';
90
91 return sprintflags_ex(outstr, open_mode_flags, flags, sep,
92 XLAT_STYLE_ABBREV) ?: outstr;
93 }
94
95 const char *
96 sprint_open_modes(unsigned int flags)
97 {
98 return sprint_open_modes64(flags);
99 }
100
101 static void
102 tprint_open_modes64(uint64_t flags)
103 {
104 print_xlat_ex(flags, sprint_open_modes64(flags) + sizeof("flags"),
105 XLAT_STYLE_DEFAULT);
106 }
107 void
108 tprint_open_modes(unsigned int flags)
109 {
110 tprint_open_modes64(flags);
111 }
112
113 static int
114 decode_open(struct tcb *tcp, int offset)
115 {
116 /* pathname */
117 printpath(tcp, tcp->u_arg[offset]);
118 tprint_arg_next();
119
120 /* flags */
121 tprint_open_modes(tcp->u_arg[offset + 1]);
122
123 if (tcp->u_arg[offset + 1] & (O_CREAT | __O_TMPFILE)) {
124 tprint_arg_next();
125
126 /* mode */
127 print_numeric_umode_t(tcp->u_arg[offset + 2]);
128 }
129
130 return RVAL_DECODED | RVAL_FD;
131 }
132
133 SYS_FUNC(open)
134 {
135 return decode_open(tcp, 0);
136 }
137
138 static void
139 print_open_how(struct tcb *tcp, kernel_ulong_t addr, kernel_ulong_t size)
140 {
141 enum { OPEN_HOW_MIN_SIZE = 24 };
142
143 struct open_how how;
144
145 if (size < OPEN_HOW_MIN_SIZE) {
146 printaddr(addr);
147 return;
148 }
149 if (umoven_or_printaddr(tcp, addr, MIN(size, sizeof(how)), &how))
150 return;
151
152 tprint_struct_begin();
153 PRINT_FIELD_OBJ_VAL(how, flags, tprint_open_modes64);
154 if ((how.flags & (O_CREAT | __O_TMPFILE)) || how.mode) {
155 tprint_struct_next();
156 PRINT_FIELD_OBJ_U(how, mode, print_numeric_ll_umode_t);
157 }
158 tprint_struct_next();
159 PRINT_FIELD_FLAGS(how, resolve, open_resolve_flags, "RESOLVE_???");
160
161 if (size > sizeof(how)) {
162 print_nonzero_bytes(tcp, tprint_struct_next, addr, sizeof(how),
163 MIN(size, get_pagesize()), QUOTE_FORCE_HEX);
164 }
165
166 tprint_struct_end();
167 }
168
169 SYS_FUNC(openat)
170 {
171 /* dirfd */
172 print_dirfd(tcp, tcp->u_arg[0]);
173 tprint_arg_next();
174
175 return decode_open(tcp, 1);
176 }
177
178 SYS_FUNC(openat2)
179 {
180 /* dirfd */
181 print_dirfd(tcp, tcp->u_arg[0]);
182 tprint_arg_next();
183
184 /* pathname */
185 printpath(tcp, tcp->u_arg[1]);
186 tprint_arg_next();
187
188 /* how */
189 print_open_how(tcp, tcp->u_arg[2], tcp->u_arg[3]);
190 tprint_arg_next();
191
192 /* size */
193 PRINT_VAL_U(tcp->u_arg[3]);
194
195 return RVAL_DECODED | RVAL_FD;
196 }
197
198 SYS_FUNC(creat)
199 {
200 /* pathname */
201 printpath(tcp, tcp->u_arg[0]);
202 tprint_arg_next();
203
204 /* mode */
205 print_numeric_umode_t(tcp->u_arg[1]);
206
207 return RVAL_DECODED | RVAL_FD;
208 }