Commit | Line | Data |
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09c434b8 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1da177e4 LT |
2 | /* |
3 | * linux/fs/binfmt_script.c | |
4 | * | |
96de0e25 | 5 | * Copyright (C) 1996 Martin von Löwis |
1da177e4 LT |
6 | * original #!-checking implemented by tytso. |
7 | */ | |
8 | ||
9 | #include <linux/module.h> | |
10 | #include <linux/string.h> | |
11 | #include <linux/stat.h> | |
1da177e4 LT |
12 | #include <linux/binfmts.h> |
13 | #include <linux/init.h> | |
14 | #include <linux/file.h> | |
1da177e4 LT |
15 | #include <linux/err.h> |
16 | #include <linux/fs.h> | |
17 | ||
b5372fe5 KC |
18 | static inline bool spacetab(char c) { return c == ' ' || c == '\t'; } |
19 | static inline char *next_non_spacetab(char *first, const char *last) | |
20 | { | |
21 | for (; first <= last; first++) | |
22 | if (!spacetab(*first)) | |
23 | return first; | |
24 | return NULL; | |
25 | } | |
26 | static inline char *next_terminator(char *first, const char *last) | |
27 | { | |
28 | for (; first <= last; first++) | |
29 | if (spacetab(*first) || !*first) | |
30 | return first; | |
31 | return NULL; | |
32 | } | |
33 | ||
71613c3b | 34 | static int load_script(struct linux_binprm *bprm) |
1da177e4 | 35 | { |
d7627467 | 36 | const char *i_arg, *i_name; |
b5372fe5 | 37 | char *cp, *buf_end; |
1da177e4 | 38 | struct file *file; |
1da177e4 LT |
39 | int retval; |
40 | ||
b5372fe5 | 41 | /* Not ours to exec if we don't start with "#!". */ |
d7402698 | 42 | if ((bprm->buf[0] != '#') || (bprm->buf[1] != '!')) |
1da177e4 | 43 | return -ENOEXEC; |
51f39a1f DD |
44 | |
45 | /* | |
46 | * If the script filename will be inaccessible after exec, typically | |
47 | * because it is a "/dev/fd/<fd>/.." path against an O_CLOEXEC fd, give | |
48 | * up now (on the assumption that the interpreter will want to load | |
49 | * this file). | |
50 | */ | |
51 | if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE) | |
52 | return -ENOENT; | |
53 | ||
b5372fe5 | 54 | /* Release since we are not mapping a binary into memory. */ |
1da177e4 LT |
55 | allow_write_access(bprm->file); |
56 | fput(bprm->file); | |
57 | bprm->file = NULL; | |
58 | ||
b5372fe5 KC |
59 | /* |
60 | * This section handles parsing the #! line into separate | |
61 | * interpreter path and argument strings. We must be careful | |
62 | * because bprm->buf is not yet guaranteed to be NUL-terminated | |
63 | * (though the buffer will have trailing NUL padding when the | |
64 | * file size was smaller than the buffer size). | |
65 | * | |
66 | * We do not want to exec a truncated interpreter path, so either | |
67 | * we find a newline (which indicates nothing is truncated), or | |
68 | * we find a space/tab/NUL after the interpreter path (which | |
69 | * itself may be preceded by spaces/tabs). Truncating the | |
70 | * arguments is fine: the interpreter can re-read the script to | |
71 | * parse them on its own. | |
72 | */ | |
73 | buf_end = bprm->buf + sizeof(bprm->buf) - 1; | |
74 | cp = strnchr(bprm->buf, sizeof(bprm->buf), '\n'); | |
75 | if (!cp) { | |
76 | cp = next_non_spacetab(bprm->buf + 2, buf_end); | |
77 | if (!cp) | |
78 | return -ENOEXEC; /* Entire buf is spaces/tabs */ | |
79 | /* | |
80 | * If there is no later space/tab/NUL we must assume the | |
81 | * interpreter path is truncated. | |
82 | */ | |
83 | if (!next_terminator(cp, buf_end)) | |
84 | return -ENOEXEC; | |
85 | cp = buf_end; | |
86 | } | |
87 | /* NUL-terminate the buffer and any trailing spaces/tabs. */ | |
1da177e4 LT |
88 | *cp = '\0'; |
89 | while (cp > bprm->buf) { | |
90 | cp--; | |
91 | if ((*cp == ' ') || (*cp == '\t')) | |
92 | *cp = '\0'; | |
93 | else | |
94 | break; | |
95 | } | |
96 | for (cp = bprm->buf+2; (*cp == ' ') || (*cp == '\t'); cp++); | |
c2315c18 | 97 | if (*cp == '\0') |
1da177e4 LT |
98 | return -ENOEXEC; /* No interpreter name found */ |
99 | i_name = cp; | |
100 | i_arg = NULL; | |
101 | for ( ; *cp && (*cp != ' ') && (*cp != '\t'); cp++) | |
102 | /* nothing */ ; | |
103 | while ((*cp == ' ') || (*cp == '\t')) | |
104 | *cp++ = '\0'; | |
105 | if (*cp) | |
106 | i_arg = cp; | |
1da177e4 LT |
107 | /* |
108 | * OK, we've parsed out the interpreter name and | |
109 | * (optional) argument. | |
110 | * Splice in (1) the interpreter's name for argv[0] | |
111 | * (2) (optional) argument to interpreter | |
112 | * (3) filename of shell script (replace argv[0]) | |
113 | * | |
114 | * This is done in reverse order, because of how the | |
115 | * user environment and arguments are stored. | |
116 | */ | |
b6a2fea3 OW |
117 | retval = remove_arg_zero(bprm); |
118 | if (retval) | |
119 | return retval; | |
1da177e4 | 120 | retval = copy_strings_kernel(1, &bprm->interp, bprm); |
c2315c18 ON |
121 | if (retval < 0) |
122 | return retval; | |
1da177e4 LT |
123 | bprm->argc++; |
124 | if (i_arg) { | |
125 | retval = copy_strings_kernel(1, &i_arg, bprm); | |
c2315c18 ON |
126 | if (retval < 0) |
127 | return retval; | |
1da177e4 LT |
128 | bprm->argc++; |
129 | } | |
130 | retval = copy_strings_kernel(1, &i_name, bprm); | |
c2315c18 ON |
131 | if (retval) |
132 | return retval; | |
1da177e4 | 133 | bprm->argc++; |
c2315c18 | 134 | retval = bprm_change_interp(i_name, bprm); |
b66c5984 KC |
135 | if (retval < 0) |
136 | return retval; | |
1da177e4 LT |
137 | |
138 | /* | |
139 | * OK, now restart the process with the interpreter's dentry. | |
140 | */ | |
c2315c18 | 141 | file = open_exec(i_name); |
1da177e4 LT |
142 | if (IS_ERR(file)) |
143 | return PTR_ERR(file); | |
144 | ||
145 | bprm->file = file; | |
146 | retval = prepare_binprm(bprm); | |
147 | if (retval < 0) | |
148 | return retval; | |
3c456bfc | 149 | return search_binary_handler(bprm); |
1da177e4 LT |
150 | } |
151 | ||
152 | static struct linux_binfmt script_format = { | |
153 | .module = THIS_MODULE, | |
154 | .load_binary = load_script, | |
155 | }; | |
156 | ||
157 | static int __init init_script_binfmt(void) | |
158 | { | |
8fc3dc5a AV |
159 | register_binfmt(&script_format); |
160 | return 0; | |
1da177e4 LT |
161 | } |
162 | ||
163 | static void __exit exit_script_binfmt(void) | |
164 | { | |
165 | unregister_binfmt(&script_format); | |
166 | } | |
167 | ||
168 | core_initcall(init_script_binfmt); | |
169 | module_exit(exit_script_binfmt); | |
170 | MODULE_LICENSE("GPL"); |