Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * linux/fs/file.c |
| 3 | * |
| 4 | * Copyright (C) 1998-1999, Stephen Tweedie and Bill Hawes |
| 5 | * |
| 6 | * Manage the dynamic fd arrays in the process files_struct. |
| 7 | */ |
| 8 | |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 9 | #include <linux/syscalls.h> |
Paul Gortmaker | 630d9c4 | 2011-11-16 23:57:37 -0500 | [diff] [blame] | 10 | #include <linux/export.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 11 | #include <linux/fs.h> |
| 12 | #include <linux/mm.h> |
Andrew Morton | 6d4831c | 2011-04-27 15:26:41 -0700 | [diff] [blame] | 13 | #include <linux/mmzone.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 14 | #include <linux/time.h> |
Alexey Dobriyan | d43c36d | 2009-10-07 17:09:06 +0400 | [diff] [blame] | 15 | #include <linux/sched.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 16 | #include <linux/slab.h> |
| 17 | #include <linux/vmalloc.h> |
| 18 | #include <linux/file.h> |
Al Viro | 9f3acc3 | 2008-04-24 07:44:08 -0400 | [diff] [blame] | 19 | #include <linux/fdtable.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 20 | #include <linux/bitops.h> |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 21 | #include <linux/interrupt.h> |
| 22 | #include <linux/spinlock.h> |
| 23 | #include <linux/rcupdate.h> |
| 24 | #include <linux/workqueue.h> |
| 25 | |
| 26 | struct fdtable_defer { |
| 27 | spinlock_t lock; |
| 28 | struct work_struct wq; |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 29 | struct fdtable *next; |
| 30 | }; |
| 31 | |
Eric Dumazet | 9cfe015 | 2008-02-06 01:37:16 -0800 | [diff] [blame] | 32 | int sysctl_nr_open __read_mostly = 1024*1024; |
Al Viro | eceea0b | 2008-05-10 10:08:32 -0400 | [diff] [blame] | 33 | int sysctl_nr_open_min = BITS_PER_LONG; |
| 34 | int sysctl_nr_open_max = 1024 * 1024; /* raised later */ |
Eric Dumazet | 9cfe015 | 2008-02-06 01:37:16 -0800 | [diff] [blame] | 35 | |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 36 | /* |
| 37 | * We use this list to defer free fdtables that have vmalloced |
| 38 | * sets/arrays. By keeping a per-cpu list, we avoid having to embed |
| 39 | * the work_struct in fdtable itself which avoids a 64 byte (i386) increase in |
| 40 | * this per-task structure. |
| 41 | */ |
| 42 | static DEFINE_PER_CPU(struct fdtable_defer, fdtable_defer_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 43 | |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 44 | static void *alloc_fdmem(size_t size) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 45 | { |
Andrew Morton | 6d4831c | 2011-04-27 15:26:41 -0700 | [diff] [blame] | 46 | /* |
| 47 | * Very large allocations can stress page reclaim, so fall back to |
| 48 | * vmalloc() if the allocation size will be considered "large" by the VM. |
| 49 | */ |
| 50 | if (size <= (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER)) { |
| 51 | void *data = kmalloc(size, GFP_KERNEL|__GFP_NOWARN); |
| 52 | if (data != NULL) |
| 53 | return data; |
| 54 | } |
Changli Gao | a892e2d | 2010-08-10 18:01:35 -0700 | [diff] [blame] | 55 | return vmalloc(size); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 56 | } |
| 57 | |
Changli Gao | a892e2d | 2010-08-10 18:01:35 -0700 | [diff] [blame] | 58 | static void free_fdmem(void *ptr) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 59 | { |
Changli Gao | a892e2d | 2010-08-10 18:01:35 -0700 | [diff] [blame] | 60 | is_vmalloc_addr(ptr) ? vfree(ptr) : kfree(ptr); |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 61 | } |
| 62 | |
Changli Gao | a892e2d | 2010-08-10 18:01:35 -0700 | [diff] [blame] | 63 | static void __free_fdtable(struct fdtable *fdt) |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 64 | { |
Changli Gao | a892e2d | 2010-08-10 18:01:35 -0700 | [diff] [blame] | 65 | free_fdmem(fdt->fd); |
| 66 | free_fdmem(fdt->open_fds); |
| 67 | kfree(fdt); |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 68 | } |
| 69 | |
David Howells | 65f27f3 | 2006-11-22 14:55:48 +0000 | [diff] [blame] | 70 | static void free_fdtable_work(struct work_struct *work) |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 71 | { |
David Howells | 65f27f3 | 2006-11-22 14:55:48 +0000 | [diff] [blame] | 72 | struct fdtable_defer *f = |
| 73 | container_of(work, struct fdtable_defer, wq); |
Dipankar Sarma | badf166 | 2005-09-09 13:04:10 -0700 | [diff] [blame] | 74 | struct fdtable *fdt; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 75 | |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 76 | spin_lock_bh(&f->lock); |
| 77 | fdt = f->next; |
| 78 | f->next = NULL; |
| 79 | spin_unlock_bh(&f->lock); |
| 80 | while(fdt) { |
| 81 | struct fdtable *next = fdt->next; |
Changli Gao | a892e2d | 2010-08-10 18:01:35 -0700 | [diff] [blame] | 82 | |
| 83 | __free_fdtable(fdt); |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 84 | fdt = next; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 85 | } |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 86 | } |
| 87 | |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 88 | static void free_fdtable_rcu(struct rcu_head *rcu) |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 89 | { |
| 90 | struct fdtable *fdt = container_of(rcu, struct fdtable, rcu); |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 91 | struct fdtable_defer *fddef; |
| 92 | |
| 93 | BUG_ON(!fdt); |
Al Viro | 1983e78 | 2012-08-15 20:06:36 -0400 | [diff] [blame] | 94 | BUG_ON(fdt->max_fds <= NR_OPEN_DEFAULT); |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 95 | |
Changli Gao | a892e2d | 2010-08-10 18:01:35 -0700 | [diff] [blame] | 96 | if (!is_vmalloc_addr(fdt->fd) && !is_vmalloc_addr(fdt->open_fds)) { |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 97 | kfree(fdt->fd); |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 98 | kfree(fdt->open_fds); |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 99 | kfree(fdt); |
| 100 | } else { |
| 101 | fddef = &get_cpu_var(fdtable_defer_list); |
| 102 | spin_lock(&fddef->lock); |
| 103 | fdt->next = fddef->next; |
| 104 | fddef->next = fdt; |
Tejun Heo | 593be07 | 2006-12-06 20:36:01 -0800 | [diff] [blame] | 105 | /* vmallocs are handled from the workqueue context */ |
| 106 | schedule_work(&fddef->wq); |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 107 | spin_unlock(&fddef->lock); |
| 108 | put_cpu_var(fdtable_defer_list); |
| 109 | } |
| 110 | } |
| 111 | |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 112 | /* |
| 113 | * Expand the fdset in the files_struct. Called with the files spinlock |
| 114 | * held for write. |
| 115 | */ |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 116 | static void copy_fdtable(struct fdtable *nfdt, struct fdtable *ofdt) |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 117 | { |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 118 | unsigned int cpy, set; |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 119 | |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 120 | BUG_ON(nfdt->max_fds < ofdt->max_fds); |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 121 | |
| 122 | cpy = ofdt->max_fds * sizeof(struct file *); |
| 123 | set = (nfdt->max_fds - ofdt->max_fds) * sizeof(struct file *); |
| 124 | memcpy(nfdt->fd, ofdt->fd, cpy); |
| 125 | memset((char *)(nfdt->fd) + cpy, 0, set); |
| 126 | |
| 127 | cpy = ofdt->max_fds / BITS_PER_BYTE; |
| 128 | set = (nfdt->max_fds - ofdt->max_fds) / BITS_PER_BYTE; |
| 129 | memcpy(nfdt->open_fds, ofdt->open_fds, cpy); |
| 130 | memset((char *)(nfdt->open_fds) + cpy, 0, set); |
| 131 | memcpy(nfdt->close_on_exec, ofdt->close_on_exec, cpy); |
| 132 | memset((char *)(nfdt->close_on_exec) + cpy, 0, set); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 133 | } |
| 134 | |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 135 | static struct fdtable * alloc_fdtable(unsigned int nr) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 136 | { |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 137 | struct fdtable *fdt; |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 138 | void *data; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 139 | |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 140 | /* |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 141 | * Figure out how many fds we actually want to support in this fdtable. |
| 142 | * Allocation steps are keyed to the size of the fdarray, since it |
| 143 | * grows far faster than any of the other dynamic data. We try to fit |
| 144 | * the fdarray into comfortable page-tuned chunks: starting at 1024B |
| 145 | * and growing in powers of two from there on. |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 146 | */ |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 147 | nr /= (1024 / sizeof(struct file *)); |
| 148 | nr = roundup_pow_of_two(nr + 1); |
| 149 | nr *= (1024 / sizeof(struct file *)); |
Al Viro | 5c598b3 | 2008-04-27 20:04:15 -0400 | [diff] [blame] | 150 | /* |
| 151 | * Note that this can drive nr *below* what we had passed if sysctl_nr_open |
| 152 | * had been set lower between the check in expand_files() and here. Deal |
| 153 | * with that in caller, it's cheaper that way. |
| 154 | * |
| 155 | * We make sure that nr remains a multiple of BITS_PER_LONG - otherwise |
| 156 | * bitmaps handling below becomes unpleasant, to put it mildly... |
| 157 | */ |
| 158 | if (unlikely(nr > sysctl_nr_open)) |
| 159 | nr = ((sysctl_nr_open - 1) | (BITS_PER_LONG - 1)) + 1; |
Vadim Lobanov | bbea9f6 | 2006-12-10 02:21:12 -0800 | [diff] [blame] | 160 | |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 161 | fdt = kmalloc(sizeof(struct fdtable), GFP_KERNEL); |
| 162 | if (!fdt) |
Vadim Lobanov | bbea9f6 | 2006-12-10 02:21:12 -0800 | [diff] [blame] | 163 | goto out; |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 164 | fdt->max_fds = nr; |
| 165 | data = alloc_fdmem(nr * sizeof(struct file *)); |
| 166 | if (!data) |
| 167 | goto out_fdt; |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 168 | fdt->fd = data; |
| 169 | |
| 170 | data = alloc_fdmem(max_t(size_t, |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 171 | 2 * nr / BITS_PER_BYTE, L1_CACHE_BYTES)); |
| 172 | if (!data) |
| 173 | goto out_arr; |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 174 | fdt->open_fds = data; |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 175 | data += nr / BITS_PER_BYTE; |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 176 | fdt->close_on_exec = data; |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 177 | fdt->next = NULL; |
| 178 | |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 179 | return fdt; |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 180 | |
| 181 | out_arr: |
Changli Gao | a892e2d | 2010-08-10 18:01:35 -0700 | [diff] [blame] | 182 | free_fdmem(fdt->fd); |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 183 | out_fdt: |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 184 | kfree(fdt); |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 185 | out: |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 186 | return NULL; |
| 187 | } |
| 188 | |
| 189 | /* |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 190 | * Expand the file descriptor table. |
| 191 | * This function will allocate a new fdtable and both fd array and fdset, of |
| 192 | * the given size. |
| 193 | * Return <0 error code on error; 1 on successful completion. |
| 194 | * The files->file_lock should be held on entry, and will be held on exit. |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 195 | */ |
| 196 | static int expand_fdtable(struct files_struct *files, int nr) |
| 197 | __releases(files->file_lock) |
| 198 | __acquires(files->file_lock) |
| 199 | { |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 200 | struct fdtable *new_fdt, *cur_fdt; |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 201 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 202 | spin_unlock(&files->file_lock); |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 203 | new_fdt = alloc_fdtable(nr); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 204 | spin_lock(&files->file_lock); |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 205 | if (!new_fdt) |
| 206 | return -ENOMEM; |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 207 | /* |
Al Viro | 5c598b3 | 2008-04-27 20:04:15 -0400 | [diff] [blame] | 208 | * extremely unlikely race - sysctl_nr_open decreased between the check in |
| 209 | * caller and alloc_fdtable(). Cheaper to catch it here... |
| 210 | */ |
| 211 | if (unlikely(new_fdt->max_fds <= nr)) { |
Changli Gao | a892e2d | 2010-08-10 18:01:35 -0700 | [diff] [blame] | 212 | __free_fdtable(new_fdt); |
Al Viro | 5c598b3 | 2008-04-27 20:04:15 -0400 | [diff] [blame] | 213 | return -EMFILE; |
| 214 | } |
| 215 | /* |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 216 | * Check again since another task may have expanded the fd table while |
| 217 | * we dropped the lock |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 218 | */ |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 219 | cur_fdt = files_fdtable(files); |
Vadim Lobanov | bbea9f6 | 2006-12-10 02:21:12 -0800 | [diff] [blame] | 220 | if (nr >= cur_fdt->max_fds) { |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 221 | /* Continue as planned */ |
| 222 | copy_fdtable(new_fdt, cur_fdt); |
| 223 | rcu_assign_pointer(files->fdt, new_fdt); |
Vadim Lobanov | 4fd4581 | 2006-12-10 02:21:17 -0800 | [diff] [blame] | 224 | if (cur_fdt->max_fds > NR_OPEN_DEFAULT) |
Al Viro | 1983e78 | 2012-08-15 20:06:36 -0400 | [diff] [blame] | 225 | call_rcu(&cur_fdt->rcu, free_fdtable_rcu); |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 226 | } else { |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 227 | /* Somebody else expanded, so undo our attempt */ |
Changli Gao | a892e2d | 2010-08-10 18:01:35 -0700 | [diff] [blame] | 228 | __free_fdtable(new_fdt); |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 229 | } |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 230 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 231 | } |
| 232 | |
| 233 | /* |
| 234 | * Expand files. |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 235 | * This function will expand the file structures, if the requested size exceeds |
| 236 | * the current capacity and there is room for expansion. |
| 237 | * Return <0 error code on error; 0 when nothing done; 1 when files were |
| 238 | * expanded and execution may have blocked. |
| 239 | * The files->file_lock should be held on entry, and will be held on exit. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 240 | */ |
Al Viro | ad47bd7 | 2012-08-21 20:11:34 -0400 | [diff] [blame] | 241 | static int expand_files(struct files_struct *files, int nr) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 242 | { |
Dipankar Sarma | badf166 | 2005-09-09 13:04:10 -0700 | [diff] [blame] | 243 | struct fdtable *fdt; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 244 | |
Dipankar Sarma | badf166 | 2005-09-09 13:04:10 -0700 | [diff] [blame] | 245 | fdt = files_fdtable(files); |
Al Viro | 4e1e018 | 2008-07-26 16:01:20 -0400 | [diff] [blame] | 246 | |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 247 | /* Do we need to expand? */ |
Vadim Lobanov | bbea9f6 | 2006-12-10 02:21:12 -0800 | [diff] [blame] | 248 | if (nr < fdt->max_fds) |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 249 | return 0; |
Al Viro | 4e1e018 | 2008-07-26 16:01:20 -0400 | [diff] [blame] | 250 | |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 251 | /* Can we expand? */ |
Eric Dumazet | 9cfe015 | 2008-02-06 01:37:16 -0800 | [diff] [blame] | 252 | if (nr >= sysctl_nr_open) |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 253 | return -EMFILE; |
| 254 | |
| 255 | /* All good, so we try */ |
| 256 | return expand_fdtable(files, nr); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 257 | } |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 258 | |
Al Viro | b8318b0 | 2012-08-21 20:09:42 -0400 | [diff] [blame] | 259 | static inline void __set_close_on_exec(int fd, struct fdtable *fdt) |
| 260 | { |
| 261 | __set_bit(fd, fdt->close_on_exec); |
| 262 | } |
| 263 | |
| 264 | static inline void __clear_close_on_exec(int fd, struct fdtable *fdt) |
| 265 | { |
| 266 | __clear_bit(fd, fdt->close_on_exec); |
| 267 | } |
| 268 | |
| 269 | static inline void __set_open_fd(int fd, struct fdtable *fdt) |
| 270 | { |
| 271 | __set_bit(fd, fdt->open_fds); |
| 272 | } |
| 273 | |
| 274 | static inline void __clear_open_fd(int fd, struct fdtable *fdt) |
| 275 | { |
| 276 | __clear_bit(fd, fdt->open_fds); |
| 277 | } |
| 278 | |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 279 | static int count_open_files(struct fdtable *fdt) |
| 280 | { |
| 281 | int size = fdt->max_fds; |
| 282 | int i; |
| 283 | |
| 284 | /* Find the last open fd */ |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 285 | for (i = size / BITS_PER_LONG; i > 0; ) { |
| 286 | if (fdt->open_fds[--i]) |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 287 | break; |
| 288 | } |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 289 | i = (i + 1) * BITS_PER_LONG; |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 290 | return i; |
| 291 | } |
| 292 | |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 293 | /* |
| 294 | * Allocate a new files structure and copy contents from the |
| 295 | * passed in files structure. |
| 296 | * errorp will be valid only when the returned files_struct is NULL. |
| 297 | */ |
| 298 | struct files_struct *dup_fd(struct files_struct *oldf, int *errorp) |
| 299 | { |
| 300 | struct files_struct *newf; |
| 301 | struct file **old_fds, **new_fds; |
| 302 | int open_files, size, i; |
| 303 | struct fdtable *old_fdt, *new_fdt; |
| 304 | |
| 305 | *errorp = -ENOMEM; |
Al Viro | afbec7f | 2008-05-08 21:11:17 -0400 | [diff] [blame] | 306 | newf = kmem_cache_alloc(files_cachep, GFP_KERNEL); |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 307 | if (!newf) |
| 308 | goto out; |
| 309 | |
Al Viro | afbec7f | 2008-05-08 21:11:17 -0400 | [diff] [blame] | 310 | atomic_set(&newf->count, 1); |
| 311 | |
| 312 | spin_lock_init(&newf->file_lock); |
| 313 | newf->next_fd = 0; |
| 314 | new_fdt = &newf->fdtab; |
| 315 | new_fdt->max_fds = NR_OPEN_DEFAULT; |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 316 | new_fdt->close_on_exec = newf->close_on_exec_init; |
| 317 | new_fdt->open_fds = newf->open_fds_init; |
Al Viro | afbec7f | 2008-05-08 21:11:17 -0400 | [diff] [blame] | 318 | new_fdt->fd = &newf->fd_array[0]; |
Al Viro | afbec7f | 2008-05-08 21:11:17 -0400 | [diff] [blame] | 319 | new_fdt->next = NULL; |
| 320 | |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 321 | spin_lock(&oldf->file_lock); |
| 322 | old_fdt = files_fdtable(oldf); |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 323 | open_files = count_open_files(old_fdt); |
| 324 | |
| 325 | /* |
| 326 | * Check whether we need to allocate a larger fd array and fd set. |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 327 | */ |
Al Viro | adbecb1 | 2008-05-08 21:19:42 -0400 | [diff] [blame] | 328 | while (unlikely(open_files > new_fdt->max_fds)) { |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 329 | spin_unlock(&oldf->file_lock); |
Al Viro | 9dec3c4 | 2008-05-08 21:02:45 -0400 | [diff] [blame] | 330 | |
Changli Gao | a892e2d | 2010-08-10 18:01:35 -0700 | [diff] [blame] | 331 | if (new_fdt != &newf->fdtab) |
| 332 | __free_fdtable(new_fdt); |
Al Viro | adbecb1 | 2008-05-08 21:19:42 -0400 | [diff] [blame] | 333 | |
Al Viro | 9dec3c4 | 2008-05-08 21:02:45 -0400 | [diff] [blame] | 334 | new_fdt = alloc_fdtable(open_files - 1); |
| 335 | if (!new_fdt) { |
| 336 | *errorp = -ENOMEM; |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 337 | goto out_release; |
Al Viro | 9dec3c4 | 2008-05-08 21:02:45 -0400 | [diff] [blame] | 338 | } |
| 339 | |
| 340 | /* beyond sysctl_nr_open; nothing to do */ |
| 341 | if (unlikely(new_fdt->max_fds < open_files)) { |
Changli Gao | a892e2d | 2010-08-10 18:01:35 -0700 | [diff] [blame] | 342 | __free_fdtable(new_fdt); |
Al Viro | 9dec3c4 | 2008-05-08 21:02:45 -0400 | [diff] [blame] | 343 | *errorp = -EMFILE; |
| 344 | goto out_release; |
| 345 | } |
Al Viro | 9dec3c4 | 2008-05-08 21:02:45 -0400 | [diff] [blame] | 346 | |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 347 | /* |
| 348 | * Reacquire the oldf lock and a pointer to its fd table |
| 349 | * who knows it may have a new bigger fd table. We need |
| 350 | * the latest pointer. |
| 351 | */ |
| 352 | spin_lock(&oldf->file_lock); |
| 353 | old_fdt = files_fdtable(oldf); |
Al Viro | adbecb1 | 2008-05-08 21:19:42 -0400 | [diff] [blame] | 354 | open_files = count_open_files(old_fdt); |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 355 | } |
| 356 | |
| 357 | old_fds = old_fdt->fd; |
| 358 | new_fds = new_fdt->fd; |
| 359 | |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 360 | memcpy(new_fdt->open_fds, old_fdt->open_fds, open_files / 8); |
| 361 | memcpy(new_fdt->close_on_exec, old_fdt->close_on_exec, open_files / 8); |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 362 | |
| 363 | for (i = open_files; i != 0; i--) { |
| 364 | struct file *f = *old_fds++; |
| 365 | if (f) { |
| 366 | get_file(f); |
| 367 | } else { |
| 368 | /* |
| 369 | * The fd may be claimed in the fd bitmap but not yet |
| 370 | * instantiated in the files array if a sibling thread |
| 371 | * is partway through open(). So make sure that this |
| 372 | * fd is available to the new process. |
| 373 | */ |
David Howells | 1dce27c | 2012-02-16 17:49:42 +0000 | [diff] [blame] | 374 | __clear_open_fd(open_files - i, new_fdt); |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 375 | } |
| 376 | rcu_assign_pointer(*new_fds++, f); |
| 377 | } |
| 378 | spin_unlock(&oldf->file_lock); |
| 379 | |
| 380 | /* compute the remainder to be cleared */ |
| 381 | size = (new_fdt->max_fds - open_files) * sizeof(struct file *); |
| 382 | |
| 383 | /* This is long word aligned thus could use a optimized version */ |
| 384 | memset(new_fds, 0, size); |
| 385 | |
| 386 | if (new_fdt->max_fds > open_files) { |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 387 | int left = (new_fdt->max_fds - open_files) / 8; |
| 388 | int start = open_files / BITS_PER_LONG; |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 389 | |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 390 | memset(&new_fdt->open_fds[start], 0, left); |
| 391 | memset(&new_fdt->close_on_exec[start], 0, left); |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 392 | } |
| 393 | |
Al Viro | afbec7f | 2008-05-08 21:11:17 -0400 | [diff] [blame] | 394 | rcu_assign_pointer(newf->fdt, new_fdt); |
| 395 | |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 396 | return newf; |
| 397 | |
| 398 | out_release: |
| 399 | kmem_cache_free(files_cachep, newf); |
| 400 | out: |
| 401 | return NULL; |
| 402 | } |
| 403 | |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 404 | static void close_files(struct files_struct * files) |
| 405 | { |
| 406 | int i, j; |
| 407 | struct fdtable *fdt; |
| 408 | |
| 409 | j = 0; |
| 410 | |
| 411 | /* |
| 412 | * It is safe to dereference the fd table without RCU or |
| 413 | * ->file_lock because this is the last reference to the |
| 414 | * files structure. But use RCU to shut RCU-lockdep up. |
| 415 | */ |
| 416 | rcu_read_lock(); |
| 417 | fdt = files_fdtable(files); |
| 418 | rcu_read_unlock(); |
| 419 | for (;;) { |
| 420 | unsigned long set; |
| 421 | i = j * BITS_PER_LONG; |
| 422 | if (i >= fdt->max_fds) |
| 423 | break; |
| 424 | set = fdt->open_fds[j++]; |
| 425 | while (set) { |
| 426 | if (set & 1) { |
| 427 | struct file * file = xchg(&fdt->fd[i], NULL); |
| 428 | if (file) { |
| 429 | filp_close(file, files); |
| 430 | cond_resched(); |
| 431 | } |
| 432 | } |
| 433 | i++; |
| 434 | set >>= 1; |
| 435 | } |
| 436 | } |
| 437 | } |
| 438 | |
| 439 | struct files_struct *get_files_struct(struct task_struct *task) |
| 440 | { |
| 441 | struct files_struct *files; |
| 442 | |
| 443 | task_lock(task); |
| 444 | files = task->files; |
| 445 | if (files) |
| 446 | atomic_inc(&files->count); |
| 447 | task_unlock(task); |
| 448 | |
| 449 | return files; |
| 450 | } |
| 451 | |
| 452 | void put_files_struct(struct files_struct *files) |
| 453 | { |
| 454 | struct fdtable *fdt; |
| 455 | |
| 456 | if (atomic_dec_and_test(&files->count)) { |
| 457 | close_files(files); |
Al Viro | b9e02af | 2012-08-15 20:00:58 -0400 | [diff] [blame] | 458 | /* not really needed, since nobody can see us */ |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 459 | rcu_read_lock(); |
| 460 | fdt = files_fdtable(files); |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 461 | rcu_read_unlock(); |
Al Viro | b9e02af | 2012-08-15 20:00:58 -0400 | [diff] [blame] | 462 | /* free the arrays if they are not embedded */ |
| 463 | if (fdt != &files->fdtab) |
| 464 | __free_fdtable(fdt); |
| 465 | kmem_cache_free(files_cachep, files); |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 466 | } |
| 467 | } |
| 468 | |
| 469 | void reset_files_struct(struct files_struct *files) |
| 470 | { |
| 471 | struct task_struct *tsk = current; |
| 472 | struct files_struct *old; |
| 473 | |
| 474 | old = tsk->files; |
| 475 | task_lock(tsk); |
| 476 | tsk->files = files; |
| 477 | task_unlock(tsk); |
| 478 | put_files_struct(old); |
| 479 | } |
| 480 | |
| 481 | void exit_files(struct task_struct *tsk) |
| 482 | { |
| 483 | struct files_struct * files = tsk->files; |
| 484 | |
| 485 | if (files) { |
| 486 | task_lock(tsk); |
| 487 | tsk->files = NULL; |
| 488 | task_unlock(tsk); |
| 489 | put_files_struct(files); |
| 490 | } |
| 491 | } |
| 492 | |
Greg Kroah-Hartman | 6ae1417 | 2012-12-21 15:16:45 -0800 | [diff] [blame^] | 493 | static void fdtable_defer_list_init(int cpu) |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 494 | { |
| 495 | struct fdtable_defer *fddef = &per_cpu(fdtable_defer_list, cpu); |
| 496 | spin_lock_init(&fddef->lock); |
David Howells | 65f27f3 | 2006-11-22 14:55:48 +0000 | [diff] [blame] | 497 | INIT_WORK(&fddef->wq, free_fdtable_work); |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 498 | fddef->next = NULL; |
| 499 | } |
| 500 | |
| 501 | void __init files_defer_init(void) |
| 502 | { |
| 503 | int i; |
KAMEZAWA Hiroyuki | 0a94502 | 2006-03-28 01:56:37 -0800 | [diff] [blame] | 504 | for_each_possible_cpu(i) |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 505 | fdtable_defer_list_init(i); |
Al Viro | eceea0b | 2008-05-10 10:08:32 -0400 | [diff] [blame] | 506 | sysctl_nr_open_max = min((size_t)INT_MAX, ~(size_t)0/sizeof(void *)) & |
| 507 | -BITS_PER_LONG; |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 508 | } |
Al Viro | f52111b | 2008-05-08 18:19:16 -0400 | [diff] [blame] | 509 | |
| 510 | struct files_struct init_files = { |
| 511 | .count = ATOMIC_INIT(1), |
| 512 | .fdt = &init_files.fdtab, |
| 513 | .fdtab = { |
| 514 | .max_fds = NR_OPEN_DEFAULT, |
| 515 | .fd = &init_files.fd_array[0], |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 516 | .close_on_exec = init_files.close_on_exec_init, |
| 517 | .open_fds = init_files.open_fds_init, |
Al Viro | f52111b | 2008-05-08 18:19:16 -0400 | [diff] [blame] | 518 | }, |
| 519 | .file_lock = __SPIN_LOCK_UNLOCKED(init_task.file_lock), |
| 520 | }; |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 521 | |
| 522 | /* |
| 523 | * allocate a file descriptor, mark it busy. |
| 524 | */ |
Al Viro | dcfadfa | 2012-08-12 17:27:30 -0400 | [diff] [blame] | 525 | int __alloc_fd(struct files_struct *files, |
| 526 | unsigned start, unsigned end, unsigned flags) |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 527 | { |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 528 | unsigned int fd; |
| 529 | int error; |
| 530 | struct fdtable *fdt; |
| 531 | |
| 532 | spin_lock(&files->file_lock); |
| 533 | repeat: |
| 534 | fdt = files_fdtable(files); |
| 535 | fd = start; |
| 536 | if (fd < files->next_fd) |
| 537 | fd = files->next_fd; |
| 538 | |
| 539 | if (fd < fdt->max_fds) |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 540 | fd = find_next_zero_bit(fdt->open_fds, fdt->max_fds, fd); |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 541 | |
Al Viro | f33ff99 | 2012-08-12 16:17:59 -0400 | [diff] [blame] | 542 | /* |
| 543 | * N.B. For clone tasks sharing a files structure, this test |
| 544 | * will limit the total number of files that can be opened. |
| 545 | */ |
| 546 | error = -EMFILE; |
| 547 | if (fd >= end) |
| 548 | goto out; |
| 549 | |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 550 | error = expand_files(files, fd); |
| 551 | if (error < 0) |
| 552 | goto out; |
| 553 | |
| 554 | /* |
| 555 | * If we needed to expand the fs array we |
| 556 | * might have blocked - try again. |
| 557 | */ |
| 558 | if (error) |
| 559 | goto repeat; |
| 560 | |
| 561 | if (start <= files->next_fd) |
| 562 | files->next_fd = fd + 1; |
| 563 | |
David Howells | 1dce27c | 2012-02-16 17:49:42 +0000 | [diff] [blame] | 564 | __set_open_fd(fd, fdt); |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 565 | if (flags & O_CLOEXEC) |
David Howells | 1dce27c | 2012-02-16 17:49:42 +0000 | [diff] [blame] | 566 | __set_close_on_exec(fd, fdt); |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 567 | else |
David Howells | 1dce27c | 2012-02-16 17:49:42 +0000 | [diff] [blame] | 568 | __clear_close_on_exec(fd, fdt); |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 569 | error = fd; |
| 570 | #if 1 |
| 571 | /* Sanity check */ |
Paul E. McKenney | 7dc5215 | 2010-02-22 17:04:52 -0800 | [diff] [blame] | 572 | if (rcu_dereference_raw(fdt->fd[fd]) != NULL) { |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 573 | printk(KERN_WARNING "alloc_fd: slot %d not NULL!\n", fd); |
| 574 | rcu_assign_pointer(fdt->fd[fd], NULL); |
| 575 | } |
| 576 | #endif |
| 577 | |
| 578 | out: |
| 579 | spin_unlock(&files->file_lock); |
| 580 | return error; |
| 581 | } |
| 582 | |
Al Viro | ad47bd7 | 2012-08-21 20:11:34 -0400 | [diff] [blame] | 583 | static int alloc_fd(unsigned start, unsigned flags) |
Al Viro | dcfadfa | 2012-08-12 17:27:30 -0400 | [diff] [blame] | 584 | { |
| 585 | return __alloc_fd(current->files, start, rlimit(RLIMIT_NOFILE), flags); |
| 586 | } |
| 587 | |
Al Viro | 1a7bd22 | 2012-08-12 17:18:05 -0400 | [diff] [blame] | 588 | int get_unused_fd_flags(unsigned flags) |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 589 | { |
Al Viro | dcfadfa | 2012-08-12 17:27:30 -0400 | [diff] [blame] | 590 | return __alloc_fd(current->files, 0, rlimit(RLIMIT_NOFILE), flags); |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 591 | } |
Al Viro | 1a7bd22 | 2012-08-12 17:18:05 -0400 | [diff] [blame] | 592 | EXPORT_SYMBOL(get_unused_fd_flags); |
Al Viro | 56007ca | 2012-08-15 21:03:26 -0400 | [diff] [blame] | 593 | |
| 594 | static void __put_unused_fd(struct files_struct *files, unsigned int fd) |
| 595 | { |
| 596 | struct fdtable *fdt = files_fdtable(files); |
| 597 | __clear_open_fd(fd, fdt); |
| 598 | if (fd < files->next_fd) |
| 599 | files->next_fd = fd; |
| 600 | } |
| 601 | |
| 602 | void put_unused_fd(unsigned int fd) |
| 603 | { |
| 604 | struct files_struct *files = current->files; |
| 605 | spin_lock(&files->file_lock); |
| 606 | __put_unused_fd(files, fd); |
| 607 | spin_unlock(&files->file_lock); |
| 608 | } |
| 609 | |
| 610 | EXPORT_SYMBOL(put_unused_fd); |
| 611 | |
| 612 | /* |
| 613 | * Install a file pointer in the fd array. |
| 614 | * |
| 615 | * The VFS is full of places where we drop the files lock between |
| 616 | * setting the open_fds bitmap and installing the file in the file |
| 617 | * array. At any such point, we are vulnerable to a dup2() race |
| 618 | * installing a file in the array before us. We need to detect this and |
| 619 | * fput() the struct file we are about to overwrite in this case. |
| 620 | * |
| 621 | * It should never happen - if we allow dup2() do it, _really_ bad things |
| 622 | * will follow. |
Al Viro | f869e8a | 2012-08-15 21:06:33 -0400 | [diff] [blame] | 623 | * |
| 624 | * NOTE: __fd_install() variant is really, really low-level; don't |
| 625 | * use it unless you are forced to by truly lousy API shoved down |
| 626 | * your throat. 'files' *MUST* be either current->files or obtained |
| 627 | * by get_files_struct(current) done by whoever had given it to you, |
| 628 | * or really bad things will happen. Normally you want to use |
| 629 | * fd_install() instead. |
Al Viro | 56007ca | 2012-08-15 21:03:26 -0400 | [diff] [blame] | 630 | */ |
| 631 | |
Al Viro | f869e8a | 2012-08-15 21:06:33 -0400 | [diff] [blame] | 632 | void __fd_install(struct files_struct *files, unsigned int fd, |
| 633 | struct file *file) |
Al Viro | 56007ca | 2012-08-15 21:03:26 -0400 | [diff] [blame] | 634 | { |
Al Viro | 56007ca | 2012-08-15 21:03:26 -0400 | [diff] [blame] | 635 | struct fdtable *fdt; |
| 636 | spin_lock(&files->file_lock); |
| 637 | fdt = files_fdtable(files); |
| 638 | BUG_ON(fdt->fd[fd] != NULL); |
| 639 | rcu_assign_pointer(fdt->fd[fd], file); |
| 640 | spin_unlock(&files->file_lock); |
| 641 | } |
| 642 | |
Al Viro | f869e8a | 2012-08-15 21:06:33 -0400 | [diff] [blame] | 643 | void fd_install(unsigned int fd, struct file *file) |
| 644 | { |
| 645 | __fd_install(current->files, fd, file); |
| 646 | } |
| 647 | |
Al Viro | 56007ca | 2012-08-15 21:03:26 -0400 | [diff] [blame] | 648 | EXPORT_SYMBOL(fd_install); |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 649 | |
Al Viro | 483ce1d | 2012-08-19 12:04:24 -0400 | [diff] [blame] | 650 | /* |
| 651 | * The same warnings as for __alloc_fd()/__fd_install() apply here... |
| 652 | */ |
| 653 | int __close_fd(struct files_struct *files, unsigned fd) |
| 654 | { |
| 655 | struct file *file; |
| 656 | struct fdtable *fdt; |
| 657 | |
| 658 | spin_lock(&files->file_lock); |
| 659 | fdt = files_fdtable(files); |
| 660 | if (fd >= fdt->max_fds) |
| 661 | goto out_unlock; |
| 662 | file = fdt->fd[fd]; |
| 663 | if (!file) |
| 664 | goto out_unlock; |
| 665 | rcu_assign_pointer(fdt->fd[fd], NULL); |
| 666 | __clear_close_on_exec(fd, fdt); |
| 667 | __put_unused_fd(files, fd); |
| 668 | spin_unlock(&files->file_lock); |
| 669 | return filp_close(file, files); |
| 670 | |
| 671 | out_unlock: |
| 672 | spin_unlock(&files->file_lock); |
| 673 | return -EBADF; |
| 674 | } |
| 675 | |
Al Viro | 6a6d27d | 2012-08-21 09:56:33 -0400 | [diff] [blame] | 676 | void do_close_on_exec(struct files_struct *files) |
| 677 | { |
| 678 | unsigned i; |
| 679 | struct fdtable *fdt; |
| 680 | |
| 681 | /* exec unshares first */ |
Al Viro | 6a6d27d | 2012-08-21 09:56:33 -0400 | [diff] [blame] | 682 | spin_lock(&files->file_lock); |
| 683 | for (i = 0; ; i++) { |
| 684 | unsigned long set; |
| 685 | unsigned fd = i * BITS_PER_LONG; |
| 686 | fdt = files_fdtable(files); |
| 687 | if (fd >= fdt->max_fds) |
| 688 | break; |
| 689 | set = fdt->close_on_exec[i]; |
| 690 | if (!set) |
| 691 | continue; |
| 692 | fdt->close_on_exec[i] = 0; |
| 693 | for ( ; set ; fd++, set >>= 1) { |
| 694 | struct file *file; |
| 695 | if (!(set & 1)) |
| 696 | continue; |
| 697 | file = fdt->fd[fd]; |
| 698 | if (!file) |
| 699 | continue; |
| 700 | rcu_assign_pointer(fdt->fd[fd], NULL); |
| 701 | __put_unused_fd(files, fd); |
| 702 | spin_unlock(&files->file_lock); |
| 703 | filp_close(file, files); |
| 704 | cond_resched(); |
| 705 | spin_lock(&files->file_lock); |
| 706 | } |
| 707 | |
| 708 | } |
| 709 | spin_unlock(&files->file_lock); |
| 710 | } |
| 711 | |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 712 | struct file *fget(unsigned int fd) |
| 713 | { |
| 714 | struct file *file; |
| 715 | struct files_struct *files = current->files; |
| 716 | |
| 717 | rcu_read_lock(); |
| 718 | file = fcheck_files(files, fd); |
| 719 | if (file) { |
| 720 | /* File object ref couldn't be taken */ |
| 721 | if (file->f_mode & FMODE_PATH || |
| 722 | !atomic_long_inc_not_zero(&file->f_count)) |
| 723 | file = NULL; |
| 724 | } |
| 725 | rcu_read_unlock(); |
| 726 | |
| 727 | return file; |
| 728 | } |
| 729 | |
| 730 | EXPORT_SYMBOL(fget); |
| 731 | |
| 732 | struct file *fget_raw(unsigned int fd) |
| 733 | { |
| 734 | struct file *file; |
| 735 | struct files_struct *files = current->files; |
| 736 | |
| 737 | rcu_read_lock(); |
| 738 | file = fcheck_files(files, fd); |
| 739 | if (file) { |
| 740 | /* File object ref couldn't be taken */ |
| 741 | if (!atomic_long_inc_not_zero(&file->f_count)) |
| 742 | file = NULL; |
| 743 | } |
| 744 | rcu_read_unlock(); |
| 745 | |
| 746 | return file; |
| 747 | } |
| 748 | |
| 749 | EXPORT_SYMBOL(fget_raw); |
| 750 | |
| 751 | /* |
| 752 | * Lightweight file lookup - no refcnt increment if fd table isn't shared. |
| 753 | * |
| 754 | * You can use this instead of fget if you satisfy all of the following |
| 755 | * conditions: |
| 756 | * 1) You must call fput_light before exiting the syscall and returning control |
| 757 | * to userspace (i.e. you cannot remember the returned struct file * after |
| 758 | * returning to userspace). |
| 759 | * 2) You must not call filp_close on the returned struct file * in between |
| 760 | * calls to fget_light and fput_light. |
| 761 | * 3) You must not clone the current task in between the calls to fget_light |
| 762 | * and fput_light. |
| 763 | * |
| 764 | * The fput_needed flag returned by fget_light should be passed to the |
| 765 | * corresponding fput_light. |
| 766 | */ |
| 767 | struct file *fget_light(unsigned int fd, int *fput_needed) |
| 768 | { |
| 769 | struct file *file; |
| 770 | struct files_struct *files = current->files; |
| 771 | |
| 772 | *fput_needed = 0; |
| 773 | if (atomic_read(&files->count) == 1) { |
| 774 | file = fcheck_files(files, fd); |
| 775 | if (file && (file->f_mode & FMODE_PATH)) |
| 776 | file = NULL; |
| 777 | } else { |
| 778 | rcu_read_lock(); |
| 779 | file = fcheck_files(files, fd); |
| 780 | if (file) { |
| 781 | if (!(file->f_mode & FMODE_PATH) && |
| 782 | atomic_long_inc_not_zero(&file->f_count)) |
| 783 | *fput_needed = 1; |
| 784 | else |
| 785 | /* Didn't get the reference, someone's freed */ |
| 786 | file = NULL; |
| 787 | } |
| 788 | rcu_read_unlock(); |
| 789 | } |
| 790 | |
| 791 | return file; |
| 792 | } |
Al Viro | 4557c66 | 2012-08-28 10:19:41 -0400 | [diff] [blame] | 793 | EXPORT_SYMBOL(fget_light); |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 794 | |
| 795 | struct file *fget_raw_light(unsigned int fd, int *fput_needed) |
| 796 | { |
| 797 | struct file *file; |
| 798 | struct files_struct *files = current->files; |
| 799 | |
| 800 | *fput_needed = 0; |
| 801 | if (atomic_read(&files->count) == 1) { |
| 802 | file = fcheck_files(files, fd); |
| 803 | } else { |
| 804 | rcu_read_lock(); |
| 805 | file = fcheck_files(files, fd); |
| 806 | if (file) { |
| 807 | if (atomic_long_inc_not_zero(&file->f_count)) |
| 808 | *fput_needed = 1; |
| 809 | else |
| 810 | /* Didn't get the reference, someone's freed */ |
| 811 | file = NULL; |
| 812 | } |
| 813 | rcu_read_unlock(); |
| 814 | } |
| 815 | |
| 816 | return file; |
| 817 | } |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 818 | |
| 819 | void set_close_on_exec(unsigned int fd, int flag) |
| 820 | { |
| 821 | struct files_struct *files = current->files; |
| 822 | struct fdtable *fdt; |
| 823 | spin_lock(&files->file_lock); |
| 824 | fdt = files_fdtable(files); |
| 825 | if (flag) |
| 826 | __set_close_on_exec(fd, fdt); |
| 827 | else |
| 828 | __clear_close_on_exec(fd, fdt); |
| 829 | spin_unlock(&files->file_lock); |
| 830 | } |
| 831 | |
| 832 | bool get_close_on_exec(unsigned int fd) |
| 833 | { |
| 834 | struct files_struct *files = current->files; |
| 835 | struct fdtable *fdt; |
| 836 | bool res; |
| 837 | rcu_read_lock(); |
| 838 | fdt = files_fdtable(files); |
| 839 | res = close_on_exec(fd, fdt); |
| 840 | rcu_read_unlock(); |
| 841 | return res; |
| 842 | } |
| 843 | |
Al Viro | 8280d16 | 2012-08-21 12:11:46 -0400 | [diff] [blame] | 844 | static int do_dup2(struct files_struct *files, |
| 845 | struct file *file, unsigned fd, unsigned flags) |
| 846 | { |
| 847 | struct file *tofree; |
| 848 | struct fdtable *fdt; |
| 849 | |
| 850 | /* |
| 851 | * We need to detect attempts to do dup2() over allocated but still |
| 852 | * not finished descriptor. NB: OpenBSD avoids that at the price of |
| 853 | * extra work in their equivalent of fget() - they insert struct |
| 854 | * file immediately after grabbing descriptor, mark it larval if |
| 855 | * more work (e.g. actual opening) is needed and make sure that |
| 856 | * fget() treats larval files as absent. Potentially interesting, |
| 857 | * but while extra work in fget() is trivial, locking implications |
| 858 | * and amount of surgery on open()-related paths in VFS are not. |
| 859 | * FreeBSD fails with -EBADF in the same situation, NetBSD "solution" |
| 860 | * deadlocks in rather amusing ways, AFAICS. All of that is out of |
| 861 | * scope of POSIX or SUS, since neither considers shared descriptor |
| 862 | * tables and this condition does not arise without those. |
| 863 | */ |
| 864 | fdt = files_fdtable(files); |
| 865 | tofree = fdt->fd[fd]; |
| 866 | if (!tofree && fd_is_open(fd, fdt)) |
| 867 | goto Ebusy; |
| 868 | get_file(file); |
| 869 | rcu_assign_pointer(fdt->fd[fd], file); |
| 870 | __set_open_fd(fd, fdt); |
| 871 | if (flags & O_CLOEXEC) |
| 872 | __set_close_on_exec(fd, fdt); |
| 873 | else |
| 874 | __clear_close_on_exec(fd, fdt); |
| 875 | spin_unlock(&files->file_lock); |
| 876 | |
| 877 | if (tofree) |
| 878 | filp_close(tofree, files); |
| 879 | |
| 880 | return fd; |
| 881 | |
| 882 | Ebusy: |
| 883 | spin_unlock(&files->file_lock); |
| 884 | return -EBUSY; |
| 885 | } |
| 886 | |
| 887 | int replace_fd(unsigned fd, struct file *file, unsigned flags) |
| 888 | { |
| 889 | int err; |
| 890 | struct files_struct *files = current->files; |
| 891 | |
| 892 | if (!file) |
| 893 | return __close_fd(files, fd); |
| 894 | |
| 895 | if (fd >= rlimit(RLIMIT_NOFILE)) |
Al Viro | 08f05c4 | 2012-10-31 03:37:48 +0000 | [diff] [blame] | 896 | return -EBADF; |
Al Viro | 8280d16 | 2012-08-21 12:11:46 -0400 | [diff] [blame] | 897 | |
| 898 | spin_lock(&files->file_lock); |
| 899 | err = expand_files(files, fd); |
| 900 | if (unlikely(err < 0)) |
| 901 | goto out_unlock; |
| 902 | return do_dup2(files, file, fd, flags); |
| 903 | |
| 904 | out_unlock: |
| 905 | spin_unlock(&files->file_lock); |
| 906 | return err; |
| 907 | } |
| 908 | |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 909 | SYSCALL_DEFINE3(dup3, unsigned int, oldfd, unsigned int, newfd, int, flags) |
| 910 | { |
| 911 | int err = -EBADF; |
Al Viro | 8280d16 | 2012-08-21 12:11:46 -0400 | [diff] [blame] | 912 | struct file *file; |
| 913 | struct files_struct *files = current->files; |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 914 | |
| 915 | if ((flags & ~O_CLOEXEC) != 0) |
| 916 | return -EINVAL; |
| 917 | |
Richard W.M. Jones | aed9764 | 2012-10-09 15:27:43 +0100 | [diff] [blame] | 918 | if (unlikely(oldfd == newfd)) |
| 919 | return -EINVAL; |
| 920 | |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 921 | if (newfd >= rlimit(RLIMIT_NOFILE)) |
Al Viro | 08f05c4 | 2012-10-31 03:37:48 +0000 | [diff] [blame] | 922 | return -EBADF; |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 923 | |
| 924 | spin_lock(&files->file_lock); |
| 925 | err = expand_files(files, newfd); |
| 926 | file = fcheck(oldfd); |
| 927 | if (unlikely(!file)) |
| 928 | goto Ebadf; |
| 929 | if (unlikely(err < 0)) { |
| 930 | if (err == -EMFILE) |
| 931 | goto Ebadf; |
| 932 | goto out_unlock; |
| 933 | } |
Al Viro | 8280d16 | 2012-08-21 12:11:46 -0400 | [diff] [blame] | 934 | return do_dup2(files, file, newfd, flags); |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 935 | |
| 936 | Ebadf: |
| 937 | err = -EBADF; |
| 938 | out_unlock: |
| 939 | spin_unlock(&files->file_lock); |
| 940 | return err; |
| 941 | } |
| 942 | |
| 943 | SYSCALL_DEFINE2(dup2, unsigned int, oldfd, unsigned int, newfd) |
| 944 | { |
| 945 | if (unlikely(newfd == oldfd)) { /* corner case */ |
| 946 | struct files_struct *files = current->files; |
| 947 | int retval = oldfd; |
| 948 | |
| 949 | rcu_read_lock(); |
| 950 | if (!fcheck_files(files, oldfd)) |
| 951 | retval = -EBADF; |
| 952 | rcu_read_unlock(); |
| 953 | return retval; |
| 954 | } |
| 955 | return sys_dup3(oldfd, newfd, 0); |
| 956 | } |
| 957 | |
| 958 | SYSCALL_DEFINE1(dup, unsigned int, fildes) |
| 959 | { |
| 960 | int ret = -EBADF; |
| 961 | struct file *file = fget_raw(fildes); |
| 962 | |
| 963 | if (file) { |
| 964 | ret = get_unused_fd(); |
| 965 | if (ret >= 0) |
| 966 | fd_install(ret, file); |
| 967 | else |
| 968 | fput(file); |
| 969 | } |
| 970 | return ret; |
| 971 | } |
| 972 | |
| 973 | int f_dupfd(unsigned int from, struct file *file, unsigned flags) |
| 974 | { |
| 975 | int err; |
| 976 | if (from >= rlimit(RLIMIT_NOFILE)) |
| 977 | return -EINVAL; |
| 978 | err = alloc_fd(from, flags); |
| 979 | if (err >= 0) { |
| 980 | get_file(file); |
| 981 | fd_install(err, file); |
| 982 | } |
| 983 | return err; |
| 984 | } |
Al Viro | c3c073f | 2012-08-21 22:32:06 -0400 | [diff] [blame] | 985 | |
| 986 | int iterate_fd(struct files_struct *files, unsigned n, |
| 987 | int (*f)(const void *, struct file *, unsigned), |
| 988 | const void *p) |
| 989 | { |
| 990 | struct fdtable *fdt; |
Al Viro | c3c073f | 2012-08-21 22:32:06 -0400 | [diff] [blame] | 991 | int res = 0; |
| 992 | if (!files) |
| 993 | return 0; |
| 994 | spin_lock(&files->file_lock); |
Al Viro | a77cfcb | 2012-11-29 22:57:33 -0500 | [diff] [blame] | 995 | for (fdt = files_fdtable(files); n < fdt->max_fds; n++) { |
| 996 | struct file *file; |
| 997 | file = rcu_dereference_check_fdtable(files, fdt->fd[n]); |
| 998 | if (!file) |
| 999 | continue; |
| 1000 | res = f(p, file, n); |
| 1001 | if (res) |
| 1002 | break; |
Al Viro | c3c073f | 2012-08-21 22:32:06 -0400 | [diff] [blame] | 1003 | } |
| 1004 | spin_unlock(&files->file_lock); |
| 1005 | return res; |
| 1006 | } |
| 1007 | EXPORT_SYMBOL(iterate_fd); |