| 1 | |
| 2 | |
| 3 | * binfmt_misc.c
|
| 4 | *
|
| 5 | * Copyright (C) 1997 Richard Günther
|
| 6 | *
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| 7 | * binfmt_misc detects binaries via a magic or filename extension and invokes
|
| 8 | * a specified wrapper. See Documentation/admin-guide/binfmt-misc.rst for more details.
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| 9 |
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| 10 |
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| 11 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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| 12 |
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| 13 | #include <linux/array_size.h>
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| 14 | #include <linux/binfmt_misc.h>
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| 15 | #include <linux/binfmts.h>
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| 16 | #include <linux/bitops.h>
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| 17 | #include <linux/bits.h>
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| 18 | #include <linux/bug.h>
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| 19 | #include <linux/cleanup.h>
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| 20 | #include <linux/cred.h>
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| 21 | #include <linux/ctype.h>
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| 22 | #include <linux/file.h>
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| 23 | #include <linux/fs.h>
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| 24 | #include <linux/fs_context.h>
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| 25 | #include <linux/init.h>
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| 26 | #include <linux/kstrtox.h>
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| 27 | #include <linux/limits.h>
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| 28 | #include <linux/list.h>
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| 29 | #include <linux/magic.h>
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| 30 | #include <linux/module.h>
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| 31 | #include <linux/printk.h>
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| 32 | #include <linux/rculist.h>
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| 33 | #include <linux/refcount.h>
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| 34 | #include <linux/seq_file.h>
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| 35 | #include <linux/slab.h>
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| 36 | #include <linux/srcu.h>
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| 37 | #include <linux/string.h>
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| 38 | #include <linux/string_helpers.h>
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| 39 | #include <linux/uaccess.h>
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| 40 | #include <linux/user_namespace.h>
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| 41 |
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| 42 | #include "internal.h"
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| 43 |
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| 44 |
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| 45 | enum binfmt_misc_entry_bits {
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| 46 | MISC_FMT_ENABLED_BIT = 0,
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| 47 | MISC_FMT_MAGIC_BIT = 1,
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| 48 | MISC_FMT_BPF_BIT = 2,
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| 49 | };
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| 50 |
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| 51 |
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| 52 | enum binfmt_misc_entry_flags {
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| 53 | MISC_FMT_PRESERVE_ARGV0 = (1U << 31),
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| 54 | MISC_FMT_OPEN_BINARY = (1U << 30),
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| 55 | MISC_FMT_CREDENTIALS = (1U << 29),
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| 56 | MISC_FMT_OPEN_FILE = (1U << 28),
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| 57 | MISC_FMT_TRANSPARENT = (1U << 27),
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| 58 | MISC_FMT_LOADER = (1U << 26),
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| 59 | MISC_FMT_DISABLED = (1U << 25),
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| 60 | };
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| 61 |
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| 62 |
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| 63 | #define MISC_FMT_INVOCATION_FLAGS (MISC_FMT_PRESERVE_ARGV0 | \
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| 64 | MISC_FMT_OPEN_BINARY | \
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| 65 | MISC_FMT_CREDENTIALS | \
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| 66 | MISC_FMT_OPEN_FILE | \
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| 67 | MISC_FMT_TRANSPARENT | \
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| 68 | MISC_FMT_LOADER)
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| 69 |
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| 70 | |
| 71 | * struct binfmt_misc_flag - a flag character of the register string
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| 72 | * @c: the character userspace writes and reads back
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| 73 | * @flag: the entry flag it sets
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| 74 | * @implies: entry flags it turns on in addition
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| 75 | * @desc: what it does, for the registration debug output
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| 76 |
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| 77 | struct binfmt_misc_flag {
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| 78 | char c;
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| 79 | unsigned long flag;
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| 80 | unsigned long implies;
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| 81 | const char *desc;
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| 82 | };
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| 83 |
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| 84 | static const struct binfmt_misc_flag misc_flags[] = {
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| 85 | { 'P', MISC_FMT_PRESERVE_ARGV0, 0, "preserve argv0" },
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| 86 | { 'O', MISC_FMT_OPEN_BINARY, 0, "open binary" },
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| 87 | { 'C', MISC_FMT_CREDENTIALS, MISC_FMT_OPEN_BINARY, "credentials from the binary" },
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| 88 | { 'F', MISC_FMT_OPEN_FILE, 0, "open interpreter file now" },
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| 89 | { 'T', MISC_FMT_TRANSPARENT, MISC_FMT_OPEN_BINARY, "transparent" },
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| 90 | { 'L', MISC_FMT_LOADER, 0, "loader substitution" },
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| 91 | { 'D', MISC_FMT_DISABLED, 0, "register disabled" },
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| 92 | };
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| 93 |
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| 94 |
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| 95 | static const struct binfmt_misc_flag *misc_flag_by_char(const char c)
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| 96 | {
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| 97 | for (int i = 0; i < ARRAY_SIZE(misc_flags); i++)
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| 98 | if (misc_flags[i].c == c)
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| 99 | return &misc_flags[i];
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| 100 | return NULL;
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| 101 | }
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| 102 |
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| 103 | static bool misc_valid_delim(const char c)
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| 104 | {
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| 105 | if (!isascii(c) || !ispunct(c))
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| 106 | return false;
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| 107 | return c != '\\';
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| 108 | }
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| 109 |
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| 110 | struct binfmt_misc_entry {
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| 111 | struct hlist_node node;
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| 112 | unsigned long flags;
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| 113 | int offset;
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| 114 | int size;
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| 115 | char *magic;
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| 116 | char *mask;
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| 117 | const char *interpreter;
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| 118 | char *name;
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| 119 | struct dentry *dentry;
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| 120 | const struct binfmt_misc_ops *bpf_ops;
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| 121 | const char *bpf_ops_name;
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| 122 | struct list_head interps;
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| 123 | refcount_t users;
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| 124 | struct rcu_head rcu;
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| 125 | char buf[];
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| 126 | };
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| 127 |
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| 128 | |
| 129 | * Max length of the register string. Determined by:
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| 130 | * - 7 delimiters
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| 131 | * - name: ~50 bytes
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| 132 | * - type: 1 byte
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| 133 | * - offset: 3 bytes (has to be smaller than BINPRM_BUF_SIZE)
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| 134 | * - magic: 128 bytes (512 in escaped form)
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| 135 | * - mask: 128 bytes (512 in escaped form)
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| 136 | * - interp: ~50 bytes
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| 137 | * - flags: 5 bytes
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| 138 | * Round that up a bit, and then back off to hold the internal data
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| 139 | * (like struct binfmt_misc_entry).
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| 140 |
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| 141 | #define MAX_REGISTER_LENGTH 1920
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| 142 |
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| 143 |
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| 144 | #define MISC_DELIM_PAD 8
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| 145 |
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| 146 |
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| 147 | DEFINE_STATIC_SRCU_FAST(bm_entries_srcu);
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| 148 |
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| 149 |
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| 150 | static bool entry_matches_magic(const struct binfmt_misc_entry *e,
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| 151 | const struct linux_binprm *bprm)
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| 152 | {
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| 153 | const char *s = bprm->buf + e->offset;
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| 154 | int i;
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| 155 |
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| 156 | if (!e->mask)
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| 157 | return !memcmp(s, e->magic, e->size);
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| 158 |
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| 159 | for (i = 0; i < e->size; i++)
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| 160 | if ((s[i] ^ e->magic[i]) & e->mask[i])
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| 161 | return false;
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| 162 | return true;
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| 163 | }
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| 164 |
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| 165 |
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| 166 | static bool entry_matches_extension(const struct binfmt_misc_entry *e,
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| 167 | const char *ext)
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| 168 | {
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| 169 | return ext && !strcmp(e->magic, ext);
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| 170 | }
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| 171 |
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| 172 | |
| 173 | * search_binfmt_handler - search for a binary handler for @bprm
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| 174 | * @misc: handle to binfmt_misc instance
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| 175 | * @bprm: binary for which we are looking for a handler
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| 176 | *
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| 177 | * Search for a binary type handler for @bprm in the list of registered binary
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| 178 | * type handlers. A 'B' entry's match program decides whether the handler
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| 179 | * applies; it may sleep to read the binary. The matched entry is returned
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| 180 | * with a reference taken while the walk still held it; a dying entry -
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| 181 | * unlinked with its last reference gone - cannot be matched and the walk
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| 182 | * moves on.
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| 183 | *
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| 184 | * The caller must hold the bm_entries_srcu read lock, which allows an
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| 185 | * entry's evaluation to sleep.
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| 186 | *
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| 187 | * Return: referenced binary type list entry on success, NULL on failure
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| 188 |
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| 189 | static struct binfmt_misc_entry *
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| 190 | search_binfmt_handler(struct binfmt_misc *misc, struct linux_binprm *bprm)
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| 191 | {
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| 192 | char *dot = strrchr(bprm->interp, '.');
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| 193 | const char *ext = dot ? dot + 1 : NULL;
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| 194 | struct binfmt_misc_entry *e;
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| 195 |
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| 196 |
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| 197 | hlist_for_each_entry_rcu(e, &misc->entries, node,
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| 198 | srcu_read_lock_held(&bm_entries_srcu)) {
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| 199 | |
| 200 | * Make sure this one is currently enabled. An entry enters
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| 201 | * the list at most once and only whole: its configuration is
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| 202 | * ordered before the rcu insertion that makes it visible
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| 203 | * here.
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| 204 |
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| 205 | if (!test_bit(MISC_FMT_ENABLED_BIT, &e->flags))
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| 206 | continue;
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| 207 |
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| 208 | if (test_bit(MISC_FMT_BPF_BIT, &e->flags)) {
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| 209 | if (!e->bpf_ops->match(bprm))
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| 210 | continue;
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| 211 | } else if (test_bit(MISC_FMT_MAGIC_BIT, &e->flags)) {
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| 212 | if (!entry_matches_magic(e, bprm))
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| 213 | continue;
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| 214 | } else {
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| 215 | if (!entry_matches_extension(e, ext))
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| 216 | continue;
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| 217 | }
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| 218 |
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| 219 |
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| 220 | if (refcount_inc_not_zero(&e->users))
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| 221 | return e;
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| 222 | }
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| 223 |
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| 224 | return NULL;
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| 225 | }
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| 226 |
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| 227 | |
| 228 | * get_binfmt_handler - try to find a binary type handler
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| 229 | * @misc: handle to binfmt_misc instance
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| 230 | * @bprm: binary for which we are looking for a handler
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| 231 | *
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| 232 | * Try to find a binfmt handler for the binary type. If one is found it is
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| 233 | * returned with a reference protecting it against removal via
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| 234 | * bm_{entry,status}_write().
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| 235 | *
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| 236 | * Return: binary type list entry on success, NULL on failure
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| 237 |
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| 238 | static struct binfmt_misc_entry *get_binfmt_handler(struct binfmt_misc *misc,
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| 239 | struct linux_binprm *bprm)
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| 240 | {
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| 241 | guard(srcu_fast)(&bm_entries_srcu);
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| 242 | return search_binfmt_handler(misc, bprm);
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| 243 | }
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| 244 |
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| 245 | |
| 246 | * binfmt_misc_find_interp - find a bound interpreter by name
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| 247 | * @interps: the interpreters the matched entry was registered with
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| 248 | * @name: the name to look for
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| 249 | *
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| 250 | * Return: the interpreter on success, NULL if @interps has none by that name
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| 251 |
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| 252 | const struct binfmt_misc_interp *
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| 253 | binfmt_misc_find_interp(const struct list_head *interps, const char *name)
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| 254 | {
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| 255 | struct binfmt_misc_interp *interp;
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| 256 |
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| 257 | list_for_each_entry(interp, interps, list)
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| 258 | if (!strcmp(interp->name, name))
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| 259 | return interp;
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| 260 | return NULL;
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| 261 | }
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| 262 |
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| 263 |
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| 264 | static void close_interp_file(struct file *f)
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| 265 | {
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| 266 | if (IS_ERR_OR_NULL(f))
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| 267 | return;
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| 268 | exe_file_allow_write_access(f);
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| 269 | filp_close(f, NULL);
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| 270 | }
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| 271 |
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| 272 | DEFINE_FREE(close_interp_file, struct file *, close_interp_file(_T))
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| 273 |
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| 274 | |
| 275 | * Open an interpreter @path for execution: now, in the writer's context,
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| 276 | * and - since binfmt_misc mounts can be unprivileged - with @cred, the
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| 277 | * credentials the control file being written was opened with, not the
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| 278 | * writer's own.
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| 279 |
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| 280 | static struct file *open_interp_file(const struct cred *cred, const char *path)
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| 281 | {
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| 282 | struct file *f;
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| 283 |
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| 284 | scoped_with_creds(cred)
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| 285 | f = open_exec(path);
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| 286 | if (IS_ERR(f))
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| 287 | pr_notice("register: failed to install interpreter %s\n", path);
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| 288 | return f;
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| 289 | }
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| 290 |
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| 291 |
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| 292 | static void entry_put_interpreters(struct binfmt_misc_entry *e)
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| 293 | {
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| 294 | struct binfmt_misc_interp *interp, *tmp;
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| 295 |
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| 296 | list_for_each_entry_safe(interp, tmp, &e->interps, list) {
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| 297 | list_del(&interp->list);
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| 298 | close_interp_file(interp->file);
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| 299 | dec_ucount(interp->ucounts, UCOUNT_BINFMT_MISC_INTERPRETERS);
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| 300 | kfree(interp);
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| 301 | }
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| 302 | }
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| 303 |
|
| 304 | |
| 305 | * entry_attach_interpreter - bind an opened interpreter to @e
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| 306 | * @e: entry being configured
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| 307 | * @name: name the load program will select it by; empty for the fixed
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| 308 | * interpreter of a static entry
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| 309 | * @path: the path @f was opened from
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| 310 | * @f: the interpreter, opened for execution
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| 311 | *
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| 312 | * Every exec runs a clone of @f, so the path decided which file is bound
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| 313 | * and nothing else: it is not resolved again, in any namespace.
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| 314 | *
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| 315 | * The caller has to have validated @name and @path, established that @e
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| 316 | * cannot be matched yet, and owns @f until this succeeds.
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| 317 | *
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| 318 | * Return: 0 on success, -ENOSPC if the entry is full or the binder is out of
|
| 319 | * UCOUNT_BINFMT_MISC_INTERPRETERS budget, a negative errno on failure
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| 320 |
|
| 321 | static int entry_attach_interpreter(struct binfmt_misc_entry *e,
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| 322 | const char *name, const char *path,
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| 323 | struct file *f)
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| 324 | {
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| 325 | size_t nlen = strlen(name), plen = strlen(path);
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| 326 | struct binfmt_misc_interp *interp;
|
| 327 | struct ucounts *ucounts;
|
| 328 |
|
| 329 | if (binfmt_misc_find_interp(&e->interps, name))
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| 330 | return -EEXIST;
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| 331 | if (list_count_nodes(&e->interps) >= BINFMT_MISC_INTERP_MAX)
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| 332 | return -ENOSPC;
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| 333 |
|
| 334 |
|
| 335 | ucounts = inc_ucount(current_user_ns(), current_euid(),
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| 336 | UCOUNT_BINFMT_MISC_INTERPRETERS);
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| 337 | if (!ucounts)
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| 338 | return -ENOSPC;
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| 339 |
|
| 340 |
|
| 341 | interp = kmalloc_flex(*interp, name, nlen + plen + 2,
|
| 342 | GFP_KERNEL_ACCOUNT);
|
| 343 | if (!interp) {
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| 344 | dec_ucount(ucounts, UCOUNT_BINFMT_MISC_INTERPRETERS);
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| 345 | return -ENOMEM;
|
| 346 | }
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| 347 |
|
| 348 | interp->path = interp->name + nlen + 1;
|
| 349 | strscpy(interp->name, name, nlen + 1);
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| 350 | strscpy(interp->name + nlen + 1, path, plen + 1);
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| 351 | interp->file = f;
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| 352 | interp->ucounts = ucounts;
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| 353 |
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| 354 | list_add_tail_rcu(&interp->list, &e->interps);
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| 355 | pr_debug("register: interpreter: %s {%s}\n", name, path);
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| 356 | return 0;
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| 357 | }
|
| 358 |
|
| 359 | static void bm_entry_free_rcu(struct rcu_head *rcu)
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| 360 | {
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| 361 | struct binfmt_misc_entry *e = container_of(rcu, struct binfmt_misc_entry, rcu);
|
| 362 |
|
| 363 |
|
| 364 | if (e->bpf_ops)
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| 365 | binfmt_misc_put_ops(e->bpf_ops);
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| 366 | kfree(e);
|
| 367 | }
|
| 368 |
|
| 369 | |
| 370 | * put_binfmt_handler - put binary handler entry
|
| 371 | * @e: entry to put
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| 372 | *
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| 373 | * Free entry syncing with load_misc_binary() and defer final free to
|
| 374 | * load_misc_binary() in case it is using the binary type handler we were
|
| 375 | * requested to remove. Also the teardown for a registration that fails
|
| 376 | * before add_entry() publishes the entry.
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| 377 |
|
| 378 | static void put_binfmt_handler(struct binfmt_misc_entry *e)
|
| 379 | {
|
| 380 | if (IS_ERR_OR_NULL(e))
|
| 381 | return;
|
| 382 |
|
| 383 | if (refcount_dec_and_test(&e->users)) {
|
| 384 | entry_put_interpreters(e);
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| 385 |
|
| 386 | call_srcu(&bm_entries_srcu, &e->rcu, bm_entry_free_rcu);
|
| 387 | }
|
| 388 | }
|
| 389 |
|
| 390 | DEFINE_FREE(put_binfmt_handler, struct binfmt_misc_entry *, put_binfmt_handler(_T))
|
| 391 |
|
| 392 |
|
| 393 | static void drop_staged_selection(struct linux_binprm *bprm)
|
| 394 | {
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| 395 | kfree(bprm->bpf_interp);
|
| 396 | bprm->bpf_interp = NULL;
|
| 397 | kfree(bprm->bpf_interp_arg);
|
| 398 | bprm->bpf_interp_arg = NULL;
|
| 399 | if (bprm->bpf_interp_file) {
|
| 400 | fput(bprm->bpf_interp_file);
|
| 401 | bprm->bpf_interp_file = NULL;
|
| 402 | }
|
| 403 | bprm->bpf_flags = 0;
|
| 404 | }
|
| 405 |
|
| 406 | |
| 407 | * current_binfmt_misc - get the binfmt_misc instance of the caller's user namespace
|
| 408 | *
|
| 409 | * If a user namespace doesn't have its own binfmt_misc mount it uses the
|
| 410 | * handlers of its closest ancestor with one. This mimics the behavior of
|
| 411 | * pre-namespaced binfmt_misc where all registered handlers were available
|
| 412 | * to all users and user namespaces on the system. The init user namespace
|
| 413 | * instance is statically set up so the fallback is never reached in
|
| 414 | * practice.
|
| 415 | *
|
| 416 | * Return: the binfmt_misc instance of the caller's user namespace
|
| 417 |
|
| 418 | static struct binfmt_misc *current_binfmt_misc(void)
|
| 419 | {
|
| 420 | const struct user_namespace *user_ns;
|
| 421 | struct binfmt_misc *misc;
|
| 422 |
|
| 423 | for (user_ns = current_user_ns(); user_ns; user_ns = user_ns->parent) {
|
| 424 |
|
| 425 | misc = smp_load_acquire(&user_ns->binfmt_misc);
|
| 426 | if (misc)
|
| 427 | return misc;
|
| 428 | }
|
| 429 |
|
| 430 | return &init_binfmt_misc;
|
| 431 | }
|
| 432 |
|
| 433 | |
| 434 | * entry_select_interpreter - get the interpreter for the matched @e
|
| 435 | * @e: matched binary type handler
|
| 436 | * @bprm: binary that is being executed
|
| 437 | *
|
| 438 | * A static entry carries its interpreter path, for a 'B' entry the
|
| 439 | * handler's load program selects it, either by path or by the name of one
|
| 440 | * of the interpreters the entry bound. The match is committed, so a failing
|
| 441 | * program fails the exec.
|
| 442 | *
|
| 443 | * Return: the interpreter on success, an ERR_PTR on failure
|
| 444 |
|
| 445 | static const char *entry_select_interpreter(const struct binfmt_misc_entry *e,
|
| 446 | struct linux_binprm *bprm)
|
| 447 | {
|
| 448 | int retval;
|
| 449 |
|
| 450 | |
| 451 | * Drop what a previous chain level staged before anything can pick it
|
| 452 | * up. A static entry stages nothing but consumes a staged file just
|
| 453 | * like a 'B' entry does.
|
| 454 |
|
| 455 | drop_staged_selection(bprm);
|
| 456 |
|
| 457 | if (!test_bit(MISC_FMT_BPF_BIT, &e->flags))
|
| 458 | return e->interpreter;
|
| 459 |
|
| 460 |
|
| 461 | bprm->bpf_interps = &e->interps;
|
| 462 | retval = e->bpf_ops->load(bprm);
|
| 463 | bprm->bpf_interps = NULL;
|
| 464 | if (retval) {
|
| 465 |
|
| 466 | if (retval > 0 || retval < -MAX_ERRNO)
|
| 467 | retval = -ENOEXEC;
|
| 468 | goto drop_staged;
|
| 469 | }
|
| 470 |
|
| 471 |
|
| 472 | if (!bprm->bpf_interp) {
|
| 473 | retval = -ENOEXEC;
|
| 474 | goto drop_staged;
|
| 475 | }
|
| 476 |
|
| 477 | return bprm->bpf_interp;
|
| 478 |
|
| 479 | drop_staged:
|
| 480 |
|
| 481 | drop_staged_selection(bprm);
|
| 482 | return ERR_PTR(retval);
|
| 483 | }
|
| 484 |
|
| 485 | |
| 486 | * entry_invocation_flags - the invocation flags in effect for this exec
|
| 487 | * @e: matched binary type handler
|
| 488 | * @bprm: binary that is being executed
|
| 489 | *
|
| 490 | * A static entry fixes its flags at registration, a 'B' entry's load program
|
| 491 | * picks them per exec with bpf_binprm_set_flags(). Translate the latter into
|
| 492 | * the former, implications included, so the dispatch has one set to act on.
|
| 493 | *
|
| 494 | * Return: the invocation flags for this exec
|
| 495 |
|
| 496 | static unsigned long entry_invocation_flags(const struct binfmt_misc_entry *e,
|
| 497 | struct linux_binprm *bprm)
|
| 498 | {
|
| 499 | unsigned long flags = 0;
|
| 500 | u64 bpf_flags;
|
| 501 |
|
| 502 | if (!test_bit(MISC_FMT_BPF_BIT, &e->flags))
|
| 503 | return e->flags;
|
| 504 |
|
| 505 | bpf_flags = bprm->bpf_flags;
|
| 506 |
|
| 507 | bprm->bpf_flags = 0;
|
| 508 |
|
| 509 | if (bpf_flags & BPF_BINPRM_PRESERVE_ARGV0)
|
| 510 | flags |= MISC_FMT_PRESERVE_ARGV0;
|
| 511 | if (bpf_flags & BPF_BINPRM_EXECFD)
|
| 512 | flags |= MISC_FMT_OPEN_BINARY;
|
| 513 | if (bpf_flags & BPF_BINPRM_CREDENTIALS)
|
| 514 | flags |= MISC_FMT_CREDENTIALS | MISC_FMT_OPEN_BINARY;
|
| 515 | if (bpf_flags & BPF_BINPRM_TRANSPARENT)
|
| 516 | flags |= MISC_FMT_TRANSPARENT | MISC_FMT_OPEN_BINARY;
|
| 517 | if (bpf_flags & BPF_BINPRM_LOADER)
|
| 518 | flags |= MISC_FMT_LOADER;
|
| 519 |
|
| 520 | return flags;
|
| 521 | }
|
| 522 |
|
| 523 | |
| 524 | * entry_open_interpreter - open the entry's interpreter for execution
|
| 525 | * @e: matched binary type handler
|
| 526 | * @bprm: binary that is being executed
|
| 527 | * @interpreter: the interpreter selected for this exec
|
| 528 | *
|
| 529 | * An 'F' entry hands out a clone of the file it pre-opened at registration,
|
| 530 | * and so does a 'B' entry whose load program selected one of the
|
| 531 | * interpreters it bound. Any other entry opens the selected path.
|
| 532 | *
|
| 533 | * Return: the opened interpreter on success, an ERR_PTR on failure
|
| 534 |
|
| 535 | static struct file *entry_open_interpreter(const struct binfmt_misc_entry *e,
|
| 536 | struct linux_binprm *bprm,
|
| 537 | const char *interpreter)
|
| 538 | {
|
| 539 | struct file *interp_file __free(fput) = NULL;
|
| 540 | struct binfmt_misc_interp *interp;
|
| 541 | struct file *bound;
|
| 542 | int retval;
|
| 543 |
|
| 544 | if (bprm->bpf_interp_file) {
|
| 545 | bound = bprm->bpf_interp_file;
|
| 546 | } else if (e->flags & MISC_FMT_OPEN_FILE) {
|
| 547 |
|
| 548 | interp = list_first_entry(&e->interps,
|
| 549 | struct binfmt_misc_interp, list);
|
| 550 | bound = interp->file;
|
| 551 | } else {
|
| 552 | return open_exec(interpreter);
|
| 553 | }
|
| 554 |
|
| 555 | interp_file = file_clone_open(bound);
|
| 556 | if (IS_ERR(interp_file))
|
| 557 | return interp_file;
|
| 558 |
|
| 559 | retval = exe_file_deny_write_access(interp_file);
|
| 560 | if (retval)
|
| 561 | return ERR_PTR(retval);
|
| 562 |
|
| 563 | return no_free_ptr(interp_file);
|
| 564 | }
|
| 565 |
|
| 566 | |
| 567 | * build_interp_argv - splice the interpreter invocation into the argv
|
| 568 | * @bprm: binary that is being executed
|
| 569 | * @interpreter: the interpreter selected for this exec
|
| 570 | * @flags: invocation flags in effect for this exec
|
| 571 | *
|
| 572 | * The interpreter becomes argv[0] and the binary its last argument, with an
|
| 573 | * optional staged argument in between. The caller's argv[0] is dropped
|
| 574 | * unless 'P' keeps it.
|
| 575 | *
|
| 576 | * Return: 0 on success, a negative error code on failure
|
| 577 |
|
| 578 | static int build_interp_argv(struct linux_binprm *bprm, const char *interpreter,
|
| 579 | unsigned long flags)
|
| 580 | {
|
| 581 | int retval;
|
| 582 |
|
| 583 |
|
| 584 | if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE)
|
| 585 | return -ENOENT;
|
| 586 |
|
| 587 |
|
| 588 | if (flags & MISC_FMT_PRESERVE_ARGV0) {
|
| 589 | bprm->interp_flags |= BINPRM_FLAGS_PRESERVE_ARGV0;
|
| 590 | } else {
|
| 591 | retval = remove_arg_zero(bprm);
|
| 592 | if (retval)
|
| 593 | return retval;
|
| 594 | }
|
| 595 |
|
| 596 |
|
| 597 | retval = copy_string_kernel(bprm->interp, bprm);
|
| 598 | if (retval < 0)
|
| 599 | return retval;
|
| 600 | bprm->argc++;
|
| 601 |
|
| 602 | |
| 603 | * A single optional argument to the interpreter, inserted between it
|
| 604 | * and the binary just like the argument of a #! interpreter line.
|
| 605 |
|
| 606 | if (bprm->bpf_interp_arg) {
|
| 607 | retval = copy_string_kernel(bprm->bpf_interp_arg, bprm);
|
| 608 | if (retval < 0)
|
| 609 | return retval;
|
| 610 | bprm->argc++;
|
| 611 |
|
| 612 | kfree(bprm->bpf_interp_arg);
|
| 613 | bprm->bpf_interp_arg = NULL;
|
| 614 | }
|
| 615 |
|
| 616 |
|
| 617 | retval = copy_string_kernel(interpreter, bprm);
|
| 618 | if (retval < 0)
|
| 619 | return retval;
|
| 620 | bprm->argc++;
|
| 621 |
|
| 622 | return 0;
|
| 623 | }
|
| 624 |
|
| 625 | |
| 626 | * the loader itself
|
| 627 |
|
| 628 | static int load_misc_binary(struct linux_binprm *bprm)
|
| 629 | {
|
| 630 | struct binfmt_misc_entry *fmt __free(put_binfmt_handler) = NULL;
|
| 631 | const char *interpreter;
|
| 632 | struct file *interp_file;
|
| 633 | struct binfmt_misc *misc;
|
| 634 | unsigned long flags;
|
| 635 | int retval;
|
| 636 |
|
| 637 |
|
| 638 | WARN_ON_ONCE(bprm->loader);
|
| 639 |
|
| 640 | misc = current_binfmt_misc();
|
| 641 | if (!READ_ONCE(misc->enabled))
|
| 642 | return -ENOEXEC;
|
| 643 |
|
| 644 | fmt = get_binfmt_handler(misc, bprm);
|
| 645 | if (!fmt)
|
| 646 | return -ENOEXEC;
|
| 647 |
|
| 648 | interpreter = entry_select_interpreter(fmt, bprm);
|
| 649 | if (IS_ERR(interpreter))
|
| 650 | return PTR_ERR(interpreter);
|
| 651 |
|
| 652 | flags = entry_invocation_flags(fmt, bprm);
|
| 653 |
|
| 654 |
|
| 655 | if ((flags & (MISC_FMT_LOADER | MISC_FMT_TRANSPARENT)) &&
|
| 656 | bprm->bpf_interp_arg)
|
| 657 | return -EINVAL;
|
| 658 |
|
| 659 | |
| 660 | * Stash the interpreter for binfmt_elf to consume in place of the
|
| 661 | * binary's PT_INTERP and decline the match, so the search continues
|
| 662 | * to the real format in the same round.
|
| 663 |
|
| 664 | if (flags & MISC_FMT_LOADER) {
|
| 665 | interp_file = entry_open_interpreter(fmt, bprm, interpreter);
|
| 666 | if (IS_ERR(interp_file)) {
|
| 667 | retval = PTR_ERR(interp_file);
|
| 668 |
|
| 669 | return retval == -ENOEXEC ? -EACCES : retval;
|
| 670 | }
|
| 671 |
|
| 672 | bprm->loader = interp_file;
|
| 673 | return -ENOEXEC;
|
| 674 | }
|
| 675 |
|
| 676 | if (!(flags & MISC_FMT_TRANSPARENT)) {
|
| 677 | retval = build_interp_argv(bprm, interpreter, flags);
|
| 678 | if (retval)
|
| 679 | return retval;
|
| 680 | }
|
| 681 |
|
| 682 |
|
| 683 | retval = bprm_change_interp(interpreter, bprm);
|
| 684 | if (retval < 0)
|
| 685 | return retval;
|
| 686 |
|
| 687 | interp_file = entry_open_interpreter(fmt, bprm, interpreter);
|
| 688 | if (IS_ERR(interp_file))
|
| 689 | return PTR_ERR(interp_file);
|
| 690 |
|
| 691 |
|
| 692 | if (flags & MISC_FMT_TRANSPARENT)
|
| 693 | bprm->interp_flags |= BINPRM_FLAGS_TRANSPARENT_INTERP;
|
| 694 |
|
| 695 | bprm->interpreter = interp_file;
|
| 696 | if (flags & MISC_FMT_OPEN_BINARY)
|
| 697 | bprm->have_execfd = 1;
|
| 698 | if (flags & MISC_FMT_CREDENTIALS)
|
| 699 | bprm->execfd_creds = 1;
|
| 700 | return 0;
|
| 701 | }
|
| 702 |
|
| 703 |
|
| 704 |
|
| 705 | |
| 706 | * Scan the argument starting at @s up to the delimiter @del, recognising
|
| 707 | * the \x escape. Terminates the argument with a NUL and returns a pointer
|
| 708 | * past it or NULL on a malformed escape.
|
| 709 |
|
| 710 | static char *scanarg(char *s, char del)
|
| 711 | {
|
| 712 | char c;
|
| 713 |
|
| 714 | while ((c = *s++) != del) {
|
| 715 | if (c == '\\' && *s == 'x') {
|
| 716 | s++;
|
| 717 | if (!isxdigit(*s++))
|
| 718 | return NULL;
|
| 719 | if (!isxdigit(*s++))
|
| 720 | return NULL;
|
| 721 | }
|
| 722 | }
|
| 723 | s[-1] = '\0';
|
| 724 | return s;
|
| 725 | }
|
| 726 |
|
| 727 |
|
| 728 | static char *check_special_flags(char *p, struct binfmt_misc_entry *e)
|
| 729 | {
|
| 730 | for (;; p++) {
|
| 731 | const struct binfmt_misc_flag *f = misc_flag_by_char(*p);
|
| 732 |
|
| 733 | if (!f)
|
| 734 | return p;
|
| 735 | pr_debug("register: flag: %c (%s)\n", f->c, f->desc);
|
| 736 | e->flags |= f->flag | f->implies;
|
| 737 | }
|
| 738 | }
|
| 739 |
|
| 740 |
|
| 741 | static char *parse_magic_fields(struct binfmt_misc_entry *e, char *p, char del)
|
| 742 | {
|
| 743 | char *s;
|
| 744 |
|
| 745 |
|
| 746 | s = strchr(p, del);
|
| 747 | if (!s)
|
| 748 | return NULL;
|
| 749 | *s = '\0';
|
| 750 | if (p != s) {
|
| 751 | if (kstrtoint(p, 10, &e->offset) || e->offset < 0)
|
| 752 | return NULL;
|
| 753 | }
|
| 754 | p = s + 1;
|
| 755 | pr_debug("register: offset: %#x\n", e->offset);
|
| 756 |
|
| 757 |
|
| 758 | e->magic = p;
|
| 759 | p = scanarg(p, del);
|
| 760 | if (!p || !e->magic[0])
|
| 761 | return NULL;
|
| 762 | print_hex_dump_debug(
|
| 763 | KBUILD_MODNAME ": register: magic[raw]: ",
|
| 764 | DUMP_PREFIX_NONE, 16, 1, e->magic, p - e->magic, true);
|
| 765 |
|
| 766 |
|
| 767 | e->mask = p;
|
| 768 | p = scanarg(p, del);
|
| 769 | if (!p)
|
| 770 | return NULL;
|
| 771 | if (!e->mask[0]) {
|
| 772 | e->mask = NULL;
|
| 773 | pr_debug("register: mask[raw]: none\n");
|
| 774 | } else {
|
| 775 | print_hex_dump_debug(
|
| 776 | KBUILD_MODNAME ": register: mask[raw]: ",
|
| 777 | DUMP_PREFIX_NONE, 16, 1, e->mask, p - e->mask, true);
|
| 778 | }
|
| 779 |
|
| 780 | |
| 781 | * Decode the magic & mask fields. Note: while we might have accepted
|
| 782 | * embedded NUL bytes from above, the unescape helpers will stop at
|
| 783 | * the first one they encounter.
|
| 784 |
|
| 785 | e->size = string_unescape_inplace(e->magic, UNESCAPE_HEX);
|
| 786 | if (e->mask && string_unescape_inplace(e->mask, UNESCAPE_HEX) != e->size)
|
| 787 | return NULL;
|
| 788 | if (e->size > BINPRM_BUF_SIZE || BINPRM_BUF_SIZE - e->size < e->offset)
|
| 789 | return NULL;
|
| 790 | pr_debug("register: magic/mask length: %i\n", e->size);
|
| 791 | print_hex_dump_debug(
|
| 792 | KBUILD_MODNAME ": register: magic[decoded]: ",
|
| 793 | DUMP_PREFIX_NONE, 16, 1, e->magic, e->size, true);
|
| 794 | if (e->mask)
|
| 795 | print_hex_dump_debug(
|
| 796 | KBUILD_MODNAME ": register: mask[decoded]: ",
|
| 797 | DUMP_PREFIX_NONE, 16, 1, e->mask, e->size, true);
|
| 798 | return p;
|
| 799 | }
|
| 800 |
|
| 801 |
|
| 802 | static char *parse_extension_fields(struct binfmt_misc_entry *e, char *p,
|
| 803 | char del)
|
| 804 | {
|
| 805 |
|
| 806 | p = strchr(p, del);
|
| 807 | if (!p)
|
| 808 | return NULL;
|
| 809 | *p++ = '\0';
|
| 810 |
|
| 811 |
|
| 812 | e->magic = p;
|
| 813 | p = strchr(p, del);
|
| 814 | if (!p)
|
| 815 | return NULL;
|
| 816 | *p++ = '\0';
|
| 817 | if (!e->magic[0] || strchr(e->magic, '/'))
|
| 818 | return NULL;
|
| 819 | pr_debug("register: extension: {%s}\n", e->magic);
|
| 820 |
|
| 821 |
|
| 822 | p = strchr(p, del);
|
| 823 | if (!p)
|
| 824 | return NULL;
|
| 825 | *p++ = '\0';
|
| 826 | return p;
|
| 827 | }
|
| 828 |
|
| 829 | |
| 830 | * Parse the fields of a 'B' entry: the 'offset', 'magic' and 'mask' fields
|
| 831 | * must be empty. The handler name is carried in the 'interpreter' field.
|
| 832 |
|
| 833 | static char *parse_bpf_fields(struct binfmt_misc_entry *e, char *p, char del)
|
| 834 | {
|
| 835 |
|
| 836 | if (*p++ != del)
|
| 837 | return NULL;
|
| 838 |
|
| 839 |
|
| 840 | if (*p++ != del)
|
| 841 | return NULL;
|
| 842 |
|
| 843 |
|
| 844 | if (*p++ != del)
|
| 845 | return NULL;
|
| 846 |
|
| 847 | return p;
|
| 848 | }
|
| 849 |
|
| 850 | |
| 851 | * This registers a new binary format, it recognises the syntax
|
| 852 | * ':name:type:offset:magic:mask:interpreter:flags'
|
| 853 | * where the ':' is the IFS, that can be chosen with the first char
|
| 854 |
|
| 855 | static struct binfmt_misc_entry *create_entry(const char __user *buffer,
|
| 856 | size_t count)
|
| 857 | {
|
| 858 | struct binfmt_misc_entry *e __free(kfree) = NULL;
|
| 859 | char *buf, *p;
|
| 860 | char del;
|
| 861 |
|
| 862 | pr_debug("register: received %zu bytes\n", count);
|
| 863 |
|
| 864 |
|
| 865 | if ((count < 11) || (count > MAX_REGISTER_LENGTH))
|
| 866 | return ERR_PTR(-EINVAL);
|
| 867 |
|
| 868 | e = kmalloc_flex(*e, buf, count + MISC_DELIM_PAD, GFP_KERNEL_ACCOUNT);
|
| 869 | if (!e)
|
| 870 | return ERR_PTR(-ENOMEM);
|
| 871 |
|
| 872 | p = buf = e->buf;
|
| 873 |
|
| 874 | memset(e, 0, sizeof(*e));
|
| 875 | INIT_LIST_HEAD(&e->interps);
|
| 876 | if (copy_from_user(buf, buffer, count))
|
| 877 | return ERR_PTR(-EFAULT);
|
| 878 |
|
| 879 | del = *p++;
|
| 880 |
|
| 881 | pr_debug("register: delim: %#x\n", del);
|
| 882 |
|
| 883 | if (!misc_valid_delim(del))
|
| 884 | return ERR_PTR(-EINVAL);
|
| 885 |
|
| 886 |
|
| 887 | memset(buf + count, del, MISC_DELIM_PAD);
|
| 888 |
|
| 889 |
|
| 890 | e->name = p;
|
| 891 | p = strchr(p, del);
|
| 892 | if (!p)
|
| 893 | return ERR_PTR(-EINVAL);
|
| 894 | *p++ = '\0';
|
| 895 | if (!e->name[0] ||
|
| 896 | !strcmp(e->name, ".") ||
|
| 897 | !strcmp(e->name, "..") ||
|
| 898 | strchr(e->name, '/'))
|
| 899 | return ERR_PTR(-EINVAL);
|
| 900 |
|
| 901 | pr_debug("register: name: {%s}\n", e->name);
|
| 902 |
|
| 903 |
|
| 904 | switch (*p++) {
|
| 905 | case 'E':
|
| 906 | pr_debug("register: type: E (extension)\n");
|
| 907 | e->flags = BIT(MISC_FMT_ENABLED_BIT);
|
| 908 | break;
|
| 909 | case 'M':
|
| 910 | pr_debug("register: type: M (magic)\n");
|
| 911 | e->flags = BIT(MISC_FMT_ENABLED_BIT) | BIT(MISC_FMT_MAGIC_BIT);
|
| 912 | break;
|
| 913 | case 'B':
|
| 914 | pr_debug("register: type: B (bpf)\n");
|
| 915 | if (!IS_ENABLED(CONFIG_BINFMT_MISC_BPF))
|
| 916 | return ERR_PTR(-EINVAL);
|
| 917 | e->flags = BIT(MISC_FMT_ENABLED_BIT) | BIT(MISC_FMT_BPF_BIT);
|
| 918 | break;
|
| 919 | default:
|
| 920 | return ERR_PTR(-EINVAL);
|
| 921 | }
|
| 922 | if (*p++ != del)
|
| 923 | return ERR_PTR(-EINVAL);
|
| 924 |
|
| 925 | if (test_bit(MISC_FMT_BPF_BIT, &e->flags))
|
| 926 | p = parse_bpf_fields(e, p, del);
|
| 927 | else if (test_bit(MISC_FMT_MAGIC_BIT, &e->flags))
|
| 928 | p = parse_magic_fields(e, p, del);
|
| 929 | else
|
| 930 | p = parse_extension_fields(e, p, del);
|
| 931 | if (!p)
|
| 932 | return ERR_PTR(-EINVAL);
|
| 933 |
|
| 934 |
|
| 935 | e->interpreter = p;
|
| 936 | p = strchr(p, del);
|
| 937 | if (!p)
|
| 938 | return ERR_PTR(-EINVAL);
|
| 939 | *p++ = '\0';
|
| 940 | if (test_bit(MISC_FMT_BPF_BIT, &e->flags)) {
|
| 941 |
|
| 942 | e->bpf_ops_name = e->interpreter;
|
| 943 | e->interpreter = NULL;
|
| 944 | if (!e->bpf_ops_name[0])
|
| 945 | return ERR_PTR(-EINVAL);
|
| 946 | pr_debug("register: bpf handler: {%s}\n", e->bpf_ops_name);
|
| 947 | } else if (!e->interpreter[0]) {
|
| 948 | return ERR_PTR(-EINVAL);
|
| 949 | } else {
|
| 950 | pr_debug("register: interpreter: {%s}\n", e->interpreter);
|
| 951 | }
|
| 952 |
|
| 953 |
|
| 954 | p = check_special_flags(p, e);
|
| 955 |
|
| 956 | |
| 957 | * A bpf handler decides the invocation flags per exec with
|
| 958 | * bpf_binprm_set_flags() rather than fixing them at registration, and
|
| 959 | * the interpreters it binds pre-open what 'F' would have, so a 'B'
|
| 960 | * entry carries no invocation flags.
|
| 961 |
|
| 962 | if (test_bit(MISC_FMT_BPF_BIT, &e->flags) &&
|
| 963 | (e->flags & MISC_FMT_INVOCATION_FLAGS))
|
| 964 | return ERR_PTR(-EINVAL);
|
| 965 |
|
| 966 | |
| 967 | * 'D' is a directive for this registration rather than a lasting
|
| 968 | * property, so consume it: the entry is created disabled and stays
|
| 969 | * out of the search list until '1' is written to its entry file.
|
| 970 | * Staying out is what leaves it open to being given interpreters;
|
| 971 | * the first enable publishes it, for good.
|
| 972 |
|
| 973 | if (e->flags & MISC_FMT_DISABLED) {
|
| 974 | e->flags &= ~MISC_FMT_DISABLED;
|
| 975 | clear_bit(MISC_FMT_ENABLED_BIT, &e->flags);
|
| 976 | }
|
| 977 |
|
| 978 |
|
| 979 | if ((e->flags & MISC_FMT_TRANSPARENT) &&
|
| 980 | (e->flags & MISC_FMT_PRESERVE_ARGV0))
|
| 981 | return ERR_PTR(-EINVAL);
|
| 982 |
|
| 983 |
|
| 984 | if ((e->flags & MISC_FMT_LOADER) &&
|
| 985 | (e->flags & (MISC_FMT_TRANSPARENT | MISC_FMT_PRESERVE_ARGV0 |
|
| 986 | MISC_FMT_CREDENTIALS | MISC_FMT_OPEN_BINARY)))
|
| 987 | return ERR_PTR(-EINVAL);
|
| 988 |
|
| 989 | if (*p == '\n')
|
| 990 | p++;
|
| 991 | if (p != buf + count)
|
| 992 | return ERR_PTR(-EINVAL);
|
| 993 |
|
| 994 |
|
| 995 | if ((e->flags & (MISC_FMT_LOADER | MISC_FMT_CREDENTIALS)) &&
|
| 996 | !(e->flags & MISC_FMT_OPEN_FILE) &&
|
| 997 | e->interpreter[0] != '/')
|
| 998 | return ERR_PTR(-EINVAL);
|
| 999 |
|
| 1000 |
|
| 1001 | refcount_set(&e->users, 1);
|
| 1002 | return no_free_ptr(e);
|
| 1003 | }
|
| 1004 |
|
| 1005 |
|
| 1006 | enum bm_command {
|
| 1007 | BM_CMD_IGNORE,
|
| 1008 | BM_CMD_DISABLE,
|
| 1009 | BM_CMD_ENABLE,
|
| 1010 | BM_CMD_REMOVE,
|
| 1011 | };
|
| 1012 |
|
| 1013 |
|
| 1014 | #define MAX_COMMAND_LENGTH 3
|
| 1015 |
|
| 1016 | |
| 1017 | * Parse what userspace wrote to /status or an entry file: '1' enables,
|
| 1018 | * '0' disables and '-1' removes the entry or all entries.
|
| 1019 |
|
| 1020 | static int parse_command(const char *s, size_t count)
|
| 1021 | {
|
| 1022 | if (count > MAX_COMMAND_LENGTH)
|
| 1023 | return -EINVAL;
|
| 1024 | if (!count)
|
| 1025 | return BM_CMD_IGNORE;
|
| 1026 | if (s[count - 1] == '\n')
|
| 1027 | count--;
|
| 1028 | if (count == 1 && s[0] == '0')
|
| 1029 | return BM_CMD_DISABLE;
|
| 1030 | if (count == 1 && s[0] == '1')
|
| 1031 | return BM_CMD_ENABLE;
|
| 1032 | if (count == 2 && s[0] == '-' && s[1] == '1')
|
| 1033 | return BM_CMD_REMOVE;
|
| 1034 | return -EINVAL;
|
| 1035 | }
|
| 1036 |
|
| 1037 |
|
| 1038 | static int read_command(const char __user *buffer, size_t count)
|
| 1039 | {
|
| 1040 | char s[MAX_COMMAND_LENGTH + 1];
|
| 1041 |
|
| 1042 | if (count > sizeof(s) - 1)
|
| 1043 | return -EINVAL;
|
| 1044 | if (copy_from_user(s, buffer, count))
|
| 1045 | return -EFAULT;
|
| 1046 | return parse_command(s, count);
|
| 1047 | }
|
| 1048 |
|
| 1049 |
|
| 1050 |
|
| 1051 |
|
| 1052 | static struct inode *bm_root_inode(struct super_block *sb)
|
| 1053 | {
|
| 1054 | return d_inode(sb->s_root);
|
| 1055 | }
|
| 1056 |
|
| 1057 | static void bm_seq_hex(struct seq_file *m, const u8 *data, int size)
|
| 1058 | {
|
| 1059 | for (int i = 0; i < size; i++)
|
| 1060 | seq_printf(m, "%02x", data[i]);
|
| 1061 | }
|
| 1062 |
|
| 1063 | static int bm_entry_show(struct seq_file *m, void *unused)
|
| 1064 | {
|
| 1065 | struct binfmt_misc_entry *e = m->private;
|
| 1066 |
|
| 1067 | if (test_bit(MISC_FMT_ENABLED_BIT, &e->flags))
|
| 1068 | seq_puts(m, "enabled\n");
|
| 1069 | else
|
| 1070 | seq_puts(m, "disabled\n");
|
| 1071 |
|
| 1072 | if (test_bit(MISC_FMT_BPF_BIT, &e->flags)) {
|
| 1073 | struct binfmt_misc_interp *interp;
|
| 1074 |
|
| 1075 | seq_printf(m, "bpf %s\n", e->bpf_ops->name);
|
| 1076 | |
| 1077 | * A staged entry's set can still grow, so every binding is
|
| 1078 | * rcu-published. The open file pins the entry and with it
|
| 1079 | * every node, so rcu is for the tearing, not the lifetime.
|
| 1080 |
|
| 1081 | rcu_read_lock();
|
| 1082 | list_for_each_entry_rcu(interp, &e->interps, list)
|
| 1083 | seq_printf(m, "bpf-interpreter %s %s\n",
|
| 1084 | interp->name, interp->path);
|
| 1085 | rcu_read_unlock();
|
| 1086 | } else {
|
| 1087 | seq_printf(m, "interpreter %s\n", e->interpreter);
|
| 1088 | }
|
| 1089 |
|
| 1090 |
|
| 1091 | seq_puts(m, "flags: ");
|
| 1092 | for (int i = 0; i < ARRAY_SIZE(misc_flags); i++)
|
| 1093 | if (e->flags & misc_flags[i].flag)
|
| 1094 | seq_putc(m, misc_flags[i].c);
|
| 1095 | seq_putc(m, '\n');
|
| 1096 |
|
| 1097 | if (test_bit(MISC_FMT_BPF_BIT, &e->flags)) {
|
| 1098 |
|
| 1099 | } else if (!test_bit(MISC_FMT_MAGIC_BIT, &e->flags)) {
|
| 1100 | seq_printf(m, "extension .%s\n", e->magic);
|
| 1101 | } else {
|
| 1102 | seq_printf(m, "offset %i\nmagic ", e->offset);
|
| 1103 | bm_seq_hex(m, e->magic, e->size);
|
| 1104 | if (e->mask) {
|
| 1105 | seq_puts(m, "\nmask ");
|
| 1106 | bm_seq_hex(m, e->mask, e->size);
|
| 1107 | }
|
| 1108 | seq_putc(m, '\n');
|
| 1109 | }
|
| 1110 | return 0;
|
| 1111 | }
|
| 1112 |
|
| 1113 | static struct inode *bm_get_inode(struct super_block *sb, umode_t mode)
|
| 1114 | {
|
| 1115 | struct inode *inode = new_inode(sb);
|
| 1116 |
|
| 1117 | if (inode) {
|
| 1118 | inode->i_ino = get_next_ino();
|
| 1119 | inode->i_mode = mode;
|
| 1120 | simple_inode_init_ts(inode);
|
| 1121 | }
|
| 1122 | return inode;
|
| 1123 | }
|
| 1124 |
|
| 1125 | |
| 1126 | * i_binfmt_misc - retrieve struct binfmt_misc from a binfmt_misc inode
|
| 1127 | * @inode: inode of the relevant binfmt_misc instance
|
| 1128 | *
|
| 1129 | * This helper retrieves struct binfmt_misc from a binfmt_misc inode. This can
|
| 1130 | * be done without any memory barriers because we are guaranteed that
|
| 1131 | * user_ns->binfmt_misc is fully initialized. It was fully initialized when the
|
| 1132 | * binfmt_misc mount was first created.
|
| 1133 | *
|
| 1134 | * Return: struct binfmt_misc of the relevant binfmt_misc instance
|
| 1135 |
|
| 1136 | static struct binfmt_misc *i_binfmt_misc(struct inode *inode)
|
| 1137 | {
|
| 1138 | return inode->i_sb->s_user_ns->binfmt_misc;
|
| 1139 | }
|
| 1140 |
|
| 1141 | |
| 1142 | * bm_evict_inode - cleanup data associated with @inode
|
| 1143 | * @inode: inode to which the data is attached
|
| 1144 | *
|
| 1145 | * Cleanup the binary type handler data associated with @inode if a binary type
|
| 1146 | * entry is removed or the filesystem is unmounted and the super block is
|
| 1147 | * shutdown.
|
| 1148 | *
|
| 1149 | * If the ->evict call was not caused by a super block shutdown but by
|
| 1150 | * removing the entry via bm_{entry,status}_write() or unlink(2) the entry
|
| 1151 | * will have already been removed from the list. We keep the hlist_unhashed()
|
| 1152 | * check to make that explicit.
|
| 1153 |
|
| 1154 | static void bm_evict_inode(struct inode *inode)
|
| 1155 | {
|
| 1156 | struct binfmt_misc_entry *e = inode->i_private;
|
| 1157 |
|
| 1158 | clear_inode(inode);
|
| 1159 |
|
| 1160 | if (e) {
|
| 1161 | struct binfmt_misc *misc;
|
| 1162 |
|
| 1163 | misc = i_binfmt_misc(inode);
|
| 1164 | spin_lock(&misc->entries_lock);
|
| 1165 | if (!hlist_unhashed(&e->node))
|
| 1166 | hlist_del_init_rcu(&e->node);
|
| 1167 | spin_unlock(&misc->entries_lock);
|
| 1168 | put_binfmt_handler(e);
|
| 1169 | }
|
| 1170 | }
|
| 1171 |
|
| 1172 | |
| 1173 | * unlink_binfmt_handler - unhash a binary type handler
|
| 1174 | * @misc: handle to binfmt_misc instance
|
| 1175 | * @e: binary type handler to unhash
|
| 1176 | *
|
| 1177 | * Adding and removing entries via bm_{entry,register,status}_write() and
|
| 1178 | * unlink(2) happens under the exclusively held inode lock of the root
|
| 1179 | * dentry keeping the list stable for writers. load_misc_binary() walks it
|
| 1180 | * concurrently under SRCU. The entries_lock is only held around the actual
|
| 1181 | * unlink to serialize against bm_evict_inode() which unlinks entries
|
| 1182 | * during umount without holding the root inode lock.
|
| 1183 |
|
| 1184 | static void unlink_binfmt_handler(struct binfmt_misc *misc,
|
| 1185 | struct binfmt_misc_entry *e)
|
| 1186 | {
|
| 1187 | spin_lock(&misc->entries_lock);
|
| 1188 | hlist_del_init_rcu(&e->node);
|
| 1189 | spin_unlock(&misc->entries_lock);
|
| 1190 | }
|
| 1191 |
|
| 1192 | |
| 1193 | * remove_binfmt_handler - remove a binary type handler
|
| 1194 | * @misc: handle to binfmt_misc instance
|
| 1195 | * @e: binary type handler to remove
|
| 1196 | *
|
| 1197 | * Remove a binary type handler from the list of binary type handlers and
|
| 1198 | * remove its associated dentry.
|
| 1199 |
|
| 1200 | static void remove_binfmt_handler(struct binfmt_misc *misc,
|
| 1201 | struct binfmt_misc_entry *e)
|
| 1202 | {
|
| 1203 | unlink_binfmt_handler(misc, e);
|
| 1204 | locked_recursive_removal(e->dentry, NULL);
|
| 1205 | }
|
| 1206 |
|
| 1207 |
|
| 1208 | static void bm_remove_entry(struct binfmt_misc_entry *e, struct super_block *sb)
|
| 1209 | {
|
| 1210 | struct inode *root = bm_root_inode(sb);
|
| 1211 |
|
| 1212 | inode_lock_nested(root, I_MUTEX_PARENT);
|
| 1213 |
|
| 1214 | if (!d_unhashed(e->dentry))
|
| 1215 | remove_binfmt_handler(i_binfmt_misc(root), e);
|
| 1216 | inode_unlock(root);
|
| 1217 | }
|
| 1218 |
|
| 1219 |
|
| 1220 | static void bm_remove_all_entries(struct binfmt_misc *misc,
|
| 1221 | struct super_block *sb)
|
| 1222 | {
|
| 1223 | struct inode *root = bm_root_inode(sb);
|
| 1224 | struct dentry *child = NULL;
|
| 1225 |
|
| 1226 | inode_lock_nested(root, I_MUTEX_PARENT);
|
| 1227 | |
| 1228 | * Walk the directory rather than the search list: a staged entry
|
| 1229 | * is in the former but not yet in the latter. The control files
|
| 1230 | * carry no entry and stay.
|
| 1231 |
|
| 1232 | while ((child = find_next_child(sb->s_root, child))) {
|
| 1233 | struct binfmt_misc_entry *e = d_inode(child)->i_private;
|
| 1234 |
|
| 1235 | if (e)
|
| 1236 | remove_binfmt_handler(misc, e);
|
| 1237 | }
|
| 1238 | inode_unlock(root);
|
| 1239 | }
|
| 1240 |
|
| 1241 | |
| 1242 | * bm_unlink - remove a binary type handler via unlink(2)
|
| 1243 | * @dir: inode of the root directory
|
| 1244 | * @dentry: entry file to remove
|
| 1245 | *
|
| 1246 | * Removing the entry file removes its binary type handler, exactly like
|
| 1247 | * writing -1 to it does. The status and register control files can't be
|
| 1248 | * removed. The VFS calls this with the root inode lock held which
|
| 1249 | * serializes against the write based add and remove paths.
|
| 1250 |
|
| 1251 | static int bm_unlink(struct inode *dir, struct dentry *dentry)
|
| 1252 | {
|
| 1253 | struct binfmt_misc_entry *e = d_inode(dentry)->i_private;
|
| 1254 |
|
| 1255 | if (!e)
|
| 1256 | return -EPERM;
|
| 1257 |
|
| 1258 | unlink_binfmt_handler(i_binfmt_misc(dir), e);
|
| 1259 | return simple_unlink(dir, dentry);
|
| 1260 | }
|
| 1261 |
|
| 1262 | static const struct inode_operations bm_dir_inode_operations = {
|
| 1263 | .lookup = simple_lookup,
|
| 1264 | .unlink = bm_unlink,
|
| 1265 | };
|
| 1266 |
|
| 1267 |
|
| 1268 |
|
| 1269 | static int bm_entry_open(struct inode *inode, struct file *file)
|
| 1270 | {
|
| 1271 | int ret;
|
| 1272 |
|
| 1273 | ret = single_open(file, bm_entry_show, inode->i_private);
|
| 1274 | if (ret)
|
| 1275 | return ret;
|
| 1276 |
|
| 1277 |
|
| 1278 | if (file->f_mode & FMODE_WRITE)
|
| 1279 | file->f_mode |= FMODE_PWRITE;
|
| 1280 | return 0;
|
| 1281 | }
|
| 1282 |
|
| 1283 | |
| 1284 | * Longest '+<name> <path>' a write can spell, and with it the longest
|
| 1285 | * command an entry file takes: the two delimiters and a newline on top of
|
| 1286 | * the two names.
|
| 1287 |
|
| 1288 | #define MAX_BINDING_LENGTH (BINFMT_MISC_INTERP_NAME_MAX + PATH_MAX + 3)
|
| 1289 |
|
| 1290 | |
| 1291 | * bm_entry_add_interp - bind another interpreter to a staged entry
|
| 1292 | * @e: the entry
|
| 1293 | * @file: the entry file being written to, for its credentials
|
| 1294 | * @buf: the '+<name> <path>' command, parsed in place and owned by the caller
|
| 1295 | * @count: its length
|
| 1296 | *
|
| 1297 | * A 'D' entry is registered outside the search list, which is what leaves
|
| 1298 | * it open to being configured: it cannot be matched, so no exec can be
|
| 1299 | * holding its interpreters and the set can still grow. Its first enable
|
| 1300 | * publishes it and ends that. One interpreter per write, up to
|
| 1301 | * BINFMT_MISC_INTERP_MAX of them, none of which has to fit in a register
|
| 1302 | * string.
|
| 1303 | *
|
| 1304 | * Return: @count on success, a negative errno on failure
|
| 1305 |
|
| 1306 | static ssize_t bm_entry_add_interp(struct binfmt_misc_entry *e,
|
| 1307 | struct file *file, char *buf, size_t count)
|
| 1308 | {
|
| 1309 | struct file *f __free(close_interp_file) = NULL;
|
| 1310 | struct inode *root = bm_root_inode(file_inode(file)->i_sb);
|
| 1311 | size_t nlen, plen;
|
| 1312 | char *name, *path;
|
| 1313 | int retval;
|
| 1314 |
|
| 1315 |
|
| 1316 | if (!test_bit(MISC_FMT_BPF_BIT, &e->flags))
|
| 1317 | return -EINVAL;
|
| 1318 | if (!hlist_unhashed_lockless(&e->node))
|
| 1319 | return -EBUSY;
|
| 1320 |
|
| 1321 |
|
| 1322 | name = buf + 1;
|
| 1323 | path = strchr(name, ' ');
|
| 1324 | if (!path)
|
| 1325 | return -EINVAL;
|
| 1326 | *path++ = '\0';
|
| 1327 |
|
| 1328 | plen = strlen(path);
|
| 1329 |
|
| 1330 | if (path + plen != buf + count)
|
| 1331 | return -EINVAL;
|
| 1332 | if (plen && path[plen - 1] == '\n')
|
| 1333 | path[--plen] = '\0';
|
| 1334 |
|
| 1335 | if (path[0] != '/')
|
| 1336 | return -EINVAL;
|
| 1337 |
|
| 1338 | nlen = path - name - 1;
|
| 1339 | if (!nlen || nlen > BINFMT_MISC_INTERP_NAME_MAX)
|
| 1340 | return -EINVAL;
|
| 1341 |
|
| 1342 | for (const char *p = name; *p; p++)
|
| 1343 | if (!isascii(*p) || !isgraph(*p))
|
| 1344 | return -EINVAL;
|
| 1345 |
|
| 1346 |
|
| 1347 | f = open_interp_file(file->f_cred, path);
|
| 1348 | if (IS_ERR(f))
|
| 1349 | return PTR_ERR(f);
|
| 1350 |
|
| 1351 | inode_lock(root);
|
| 1352 | if (d_unhashed(e->dentry))
|
| 1353 | retval = -ENOENT;
|
| 1354 | else if (!hlist_unhashed(&e->node))
|
| 1355 | retval = -EBUSY;
|
| 1356 | else
|
| 1357 | retval = entry_attach_interpreter(e, name, path, f);
|
| 1358 | inode_unlock(root);
|
| 1359 | if (retval)
|
| 1360 | return retval;
|
| 1361 |
|
| 1362 |
|
| 1363 | retain_and_null_ptr(f);
|
| 1364 | return count;
|
| 1365 | }
|
| 1366 |
|
| 1367 | static ssize_t bm_entry_write(struct file *file, const char __user *buffer,
|
| 1368 | size_t count, loff_t *ppos)
|
| 1369 | {
|
| 1370 | struct inode *inode = file_inode(file);
|
| 1371 | struct binfmt_misc_entry *e = inode->i_private;
|
| 1372 | char *buf __free(kfree) = NULL;
|
| 1373 | int res;
|
| 1374 |
|
| 1375 |
|
| 1376 | if (count > MAX_BINDING_LENGTH)
|
| 1377 | return -E2BIG;
|
| 1378 |
|
| 1379 | buf = memdup_user_nul(buffer, count);
|
| 1380 | if (IS_ERR(buf))
|
| 1381 | return PTR_ERR(buf);
|
| 1382 |
|
| 1383 |
|
| 1384 | if (buf[0] == '+')
|
| 1385 | return bm_entry_add_interp(e, file, buf, count);
|
| 1386 |
|
| 1387 | res = parse_command(buf, count);
|
| 1388 |
|
| 1389 | switch (res) {
|
| 1390 | case BM_CMD_DISABLE:
|
| 1391 | clear_bit(MISC_FMT_ENABLED_BIT, &e->flags);
|
| 1392 | break;
|
| 1393 | case BM_CMD_ENABLE: {
|
| 1394 | struct inode *root = bm_root_inode(inode->i_sb);
|
| 1395 |
|
| 1396 | |
| 1397 | * The first enable publishes a 'D' entry into the search
|
| 1398 | * list, whole. The lock keeps that ordered against a second
|
| 1399 | * enable, against removal - a removed entry has nothing left
|
| 1400 | * to publish - and against binding: what can be matched can
|
| 1401 | * no longer be configured.
|
| 1402 |
|
| 1403 | inode_lock(root);
|
| 1404 | set_bit(MISC_FMT_ENABLED_BIT, &e->flags);
|
| 1405 | if (hlist_unhashed(&e->node) && !d_unhashed(e->dentry)) {
|
| 1406 | struct binfmt_misc *misc = i_binfmt_misc(inode);
|
| 1407 |
|
| 1408 | spin_lock(&misc->entries_lock);
|
| 1409 | hlist_add_head_rcu(&e->node, &misc->entries);
|
| 1410 | spin_unlock(&misc->entries_lock);
|
| 1411 | }
|
| 1412 | inode_unlock(root);
|
| 1413 | break;
|
| 1414 | }
|
| 1415 | case BM_CMD_REMOVE:
|
| 1416 | bm_remove_entry(e, inode->i_sb);
|
| 1417 | break;
|
| 1418 | default:
|
| 1419 | return res;
|
| 1420 | }
|
| 1421 |
|
| 1422 | return count;
|
| 1423 | }
|
| 1424 |
|
| 1425 | static const struct file_operations bm_entry_operations = {
|
| 1426 | .open = bm_entry_open,
|
| 1427 | .read = seq_read,
|
| 1428 | .write = bm_entry_write,
|
| 1429 | .llseek = seq_lseek,
|
| 1430 | .release = single_release,
|
| 1431 | };
|
| 1432 |
|
| 1433 |
|
| 1434 |
|
| 1435 |
|
| 1436 | static int add_entry(struct binfmt_misc_entry *e, struct super_block *sb)
|
| 1437 | {
|
| 1438 | struct dentry *dentry = simple_start_creating(sb->s_root, e->name);
|
| 1439 | struct inode *inode;
|
| 1440 | struct binfmt_misc *misc;
|
| 1441 |
|
| 1442 | if (IS_ERR(dentry))
|
| 1443 | return PTR_ERR(dentry);
|
| 1444 |
|
| 1445 | inode = bm_get_inode(sb, S_IFREG | 0644);
|
| 1446 | if (unlikely(!inode)) {
|
| 1447 | simple_done_creating(dentry);
|
| 1448 | return -ENOMEM;
|
| 1449 | }
|
| 1450 |
|
| 1451 | e->dentry = dentry;
|
| 1452 | inode->i_private = e;
|
| 1453 | inode->i_fop = &bm_entry_operations;
|
| 1454 |
|
| 1455 | d_make_persistent(dentry, inode);
|
| 1456 |
|
| 1457 | if (test_bit(MISC_FMT_ENABLED_BIT, &e->flags)) {
|
| 1458 | misc = i_binfmt_misc(inode);
|
| 1459 | spin_lock(&misc->entries_lock);
|
| 1460 | hlist_add_head_rcu(&e->node, &misc->entries);
|
| 1461 | spin_unlock(&misc->entries_lock);
|
| 1462 | }
|
| 1463 | simple_done_creating(dentry);
|
| 1464 | return 0;
|
| 1465 | }
|
| 1466 |
|
| 1467 | static ssize_t bm_register_write(struct file *file, const char __user *buffer,
|
| 1468 | size_t count, loff_t *ppos)
|
| 1469 | {
|
| 1470 | struct binfmt_misc_entry *e __free(put_binfmt_handler) = NULL;
|
| 1471 | struct super_block *sb = file_inode(file)->i_sb;
|
| 1472 | int err;
|
| 1473 |
|
| 1474 | e = create_entry(buffer, count);
|
| 1475 | if (IS_ERR(e))
|
| 1476 | return PTR_ERR(e);
|
| 1477 |
|
| 1478 | if (test_bit(MISC_FMT_BPF_BIT, &e->flags)) {
|
| 1479 | e->bpf_ops = binfmt_misc_get_ops(sb->s_user_ns, e->bpf_ops_name);
|
| 1480 | if (!e->bpf_ops) {
|
| 1481 | pr_notice("register: no bpf handler named %s\n",
|
| 1482 | e->bpf_ops_name);
|
| 1483 | return -ENOENT;
|
| 1484 | }
|
| 1485 | }
|
| 1486 |
|
| 1487 | if (e->flags & MISC_FMT_OPEN_FILE) {
|
| 1488 | struct file *f = open_interp_file(file->f_cred, e->interpreter);
|
| 1489 |
|
| 1490 | if (IS_ERR(f))
|
| 1491 | return PTR_ERR(f);
|
| 1492 | err = entry_attach_interpreter(e, "", e->interpreter, f);
|
| 1493 | if (err) {
|
| 1494 | close_interp_file(f);
|
| 1495 | return err;
|
| 1496 | }
|
| 1497 | }
|
| 1498 |
|
| 1499 | err = add_entry(e, sb);
|
| 1500 | if (err)
|
| 1501 | return err;
|
| 1502 |
|
| 1503 |
|
| 1504 | retain_and_null_ptr(e);
|
| 1505 | return count;
|
| 1506 | }
|
| 1507 |
|
| 1508 | static const struct file_operations bm_register_operations = {
|
| 1509 | .write = bm_register_write,
|
| 1510 | .llseek = noop_llseek,
|
| 1511 | };
|
| 1512 |
|
| 1513 |
|
| 1514 |
|
| 1515 | static ssize_t
|
| 1516 | bm_status_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
|
| 1517 | {
|
| 1518 | struct binfmt_misc *misc;
|
| 1519 | const char *s;
|
| 1520 |
|
| 1521 | misc = i_binfmt_misc(file_inode(file));
|
| 1522 | s = READ_ONCE(misc->enabled) ? "enabled\n" : "disabled\n";
|
| 1523 | return simple_read_from_buffer(buf, nbytes, ppos, s, strlen(s));
|
| 1524 | }
|
| 1525 |
|
| 1526 | static ssize_t bm_status_write(struct file *file, const char __user *buffer,
|
| 1527 | size_t count, loff_t *ppos)
|
| 1528 | {
|
| 1529 | struct binfmt_misc *misc;
|
| 1530 | int res = read_command(buffer, count);
|
| 1531 |
|
| 1532 | misc = i_binfmt_misc(file_inode(file));
|
| 1533 | switch (res) {
|
| 1534 | case BM_CMD_DISABLE:
|
| 1535 | WRITE_ONCE(misc->enabled, false);
|
| 1536 | break;
|
| 1537 | case BM_CMD_ENABLE:
|
| 1538 | WRITE_ONCE(misc->enabled, true);
|
| 1539 | break;
|
| 1540 | case BM_CMD_REMOVE:
|
| 1541 | bm_remove_all_entries(misc, file_inode(file)->i_sb);
|
| 1542 | break;
|
| 1543 | default:
|
| 1544 | return res;
|
| 1545 | }
|
| 1546 |
|
| 1547 | return count;
|
| 1548 | }
|
| 1549 |
|
| 1550 | static const struct file_operations bm_status_operations = {
|
| 1551 | .read = bm_status_read,
|
| 1552 | .write = bm_status_write,
|
| 1553 | .llseek = default_llseek,
|
| 1554 | };
|
| 1555 |
|
| 1556 |
|
| 1557 |
|
| 1558 | static const struct super_operations bm_super_ops = {
|
| 1559 | .statfs = simple_statfs,
|
| 1560 | .evict_inode = bm_evict_inode,
|
| 1561 | };
|
| 1562 |
|
| 1563 | static int bm_fill_super(struct super_block *sb, struct fs_context *fc)
|
| 1564 | {
|
| 1565 | int err;
|
| 1566 | struct user_namespace *user_ns = sb->s_user_ns;
|
| 1567 | struct binfmt_misc *misc;
|
| 1568 | static const struct tree_descr bm_files[] = {
|
| 1569 | [2] = {"status", &bm_status_operations, S_IWUSR|S_IRUGO},
|
| 1570 | [3] = {"register", &bm_register_operations, S_IWUSR},
|
| 1571 | {""}
|
| 1572 | };
|
| 1573 |
|
| 1574 |
|
| 1575 | if (user_ns != current_user_ns())
|
| 1576 | return -EINVAL;
|
| 1577 |
|
| 1578 |
|
| 1579 | sb->s_iflags |= SB_I_NOEXEC | SB_I_NODEV;
|
| 1580 | sb->s_stack_depth = FILESYSTEM_MAX_STACK_DEPTH;
|
| 1581 |
|
| 1582 | |
| 1583 | * Lazily allocate a new binfmt_misc instance for this namespace, i.e.
|
| 1584 | * do it here during the first mount of binfmt_misc. We don't need to
|
| 1585 | * waste memory for every user namespace allocation. It's likely much
|
| 1586 | * more common to not mount a separate binfmt_misc instance than it is
|
| 1587 | * to mount one.
|
| 1588 | *
|
| 1589 | * While multiple superblocks can exist they are keyed by userns in
|
| 1590 | * s_fs_info for binfmt_misc. Hence, the vfs guarantees that
|
| 1591 | * bm_fill_super() is called exactly once whenever a binfmt_misc
|
| 1592 | * superblock for a userns is created. This in turn lets us conclude
|
| 1593 | * that when a binfmt_misc superblock is created for the first time for
|
| 1594 | * a userns there's no one racing us. Therefore we don't need any
|
| 1595 | * barriers when we dereference binfmt_misc.
|
| 1596 |
|
| 1597 | misc = user_ns->binfmt_misc;
|
| 1598 | if (!misc) {
|
| 1599 | |
| 1600 | * If it turns out that most user namespaces actually want to
|
| 1601 | * register their own binary type handler and therefore all
|
| 1602 | * create their own separate binfmt_misc mounts we should
|
| 1603 | * consider turning this into a kmem cache.
|
| 1604 |
|
| 1605 | misc = kzalloc_obj(struct binfmt_misc);
|
| 1606 | if (!misc)
|
| 1607 | return -ENOMEM;
|
| 1608 |
|
| 1609 | INIT_HLIST_HEAD(&misc->entries);
|
| 1610 | spin_lock_init(&misc->entries_lock);
|
| 1611 |
|
| 1612 |
|
| 1613 | smp_store_release(&user_ns->binfmt_misc, misc);
|
| 1614 | }
|
| 1615 |
|
| 1616 | |
| 1617 | * When the binfmt_misc superblock for this userns is shutdown
|
| 1618 | * ->enabled might have been set to false and we don't reinitialize
|
| 1619 | * ->enabled again during shutdown as someone might already be mounting
|
| 1620 | * binfmt_misc again. It also would be pointless since by then we know
|
| 1621 | * that the binary type list for this binfmt_misc mount is empty making
|
| 1622 | * load_misc_binary() return -ENOEXEC independent of whether ->enabled
|
| 1623 | * is true. Instead, if someone mounts binfmt_misc for the first time or
|
| 1624 | * again we simply reset ->enabled to true.
|
| 1625 |
|
| 1626 | WRITE_ONCE(misc->enabled, true);
|
| 1627 |
|
| 1628 | err = simple_fill_super(sb, BINFMTFS_MAGIC, bm_files);
|
| 1629 | if (err)
|
| 1630 | return err;
|
| 1631 |
|
| 1632 | sb->s_op = &bm_super_ops;
|
| 1633 | d_inode(sb->s_root)->i_op = &bm_dir_inode_operations;
|
| 1634 | return 0;
|
| 1635 | }
|
| 1636 |
|
| 1637 | static void bm_free(struct fs_context *fc)
|
| 1638 | {
|
| 1639 | if (fc->s_fs_info)
|
| 1640 | put_user_ns(fc->s_fs_info);
|
| 1641 | }
|
| 1642 |
|
| 1643 | static int bm_get_tree(struct fs_context *fc)
|
| 1644 | {
|
| 1645 | return get_tree_keyed(fc, bm_fill_super, get_user_ns(fc->user_ns));
|
| 1646 | }
|
| 1647 |
|
| 1648 | static const struct fs_context_operations bm_context_ops = {
|
| 1649 | .free = bm_free,
|
| 1650 | .get_tree = bm_get_tree,
|
| 1651 | };
|
| 1652 |
|
| 1653 | static void bm_kill_sb(struct super_block *sb)
|
| 1654 | {
|
| 1655 | struct user_namespace *user_ns = sb->s_fs_info;
|
| 1656 |
|
| 1657 | kill_anon_super(sb);
|
| 1658 | put_user_ns(user_ns);
|
| 1659 | }
|
| 1660 |
|
| 1661 | static int bm_init_fs_context(struct fs_context *fc)
|
| 1662 | {
|
| 1663 | fc->ops = &bm_context_ops;
|
| 1664 | return 0;
|
| 1665 | }
|
| 1666 |
|
| 1667 | static struct linux_binfmt misc_format = {
|
| 1668 | .module = THIS_MODULE,
|
| 1669 | .load_binary = load_misc_binary,
|
| 1670 | };
|
| 1671 |
|
| 1672 | static struct file_system_type bm_fs_type = {
|
| 1673 | .owner = THIS_MODULE,
|
| 1674 | .name = "binfmt_misc",
|
| 1675 | .init_fs_context = bm_init_fs_context,
|
| 1676 | .fs_flags = FS_USERNS_MOUNT,
|
| 1677 | .kill_sb = bm_kill_sb,
|
| 1678 | };
|
| 1679 | MODULE_ALIAS_FS("binfmt_misc");
|
| 1680 |
|
| 1681 | static int __init init_misc_binfmt(void)
|
| 1682 | {
|
| 1683 | int err = register_filesystem(&bm_fs_type);
|
| 1684 | if (!err)
|
| 1685 | insert_binfmt(&misc_format);
|
| 1686 | return err;
|
| 1687 | }
|
| 1688 |
|
| 1689 | static void __exit exit_misc_binfmt(void)
|
| 1690 | {
|
| 1691 | unregister_binfmt(&misc_format);
|
| 1692 | unregister_filesystem(&bm_fs_type);
|
| 1693 |
|
| 1694 | srcu_barrier(&bm_entries_srcu);
|
| 1695 | }
|
| 1696 |
|
| 1697 | core_initcall(init_misc_binfmt);
|
| 1698 | module_exit(exit_misc_binfmt);
|
| 1699 | MODULE_DESCRIPTION("Kernel support for miscellaneous binaries");
|
| 1700 | MODULE_LICENSE("GPL");
|