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authorDaniel Borkmann <daniel@iogearbox.net>2016-11-26 01:28:08 +0100
committerDavid S. Miller <davem@davemloft.net>2016-11-27 20:38:47 -0500
commita3af5f80010625a9ffbe8edd4bae615a7516b6bc (patch)
tree55ee9e7b193b3a51ff9f0a625bcd6d4f8181876d /kernel/bpf
parent21116b7068b9b66ac16b2fe3675469f459968c3f (diff)
downloadlinux-a3af5f80010625a9ffbe8edd4bae615a7516b6bc.tar.bz2
bpf: allow for mount options to specify permissions
Since we recently converted the BPF filesystem over to use mount_nodev(), we now have the possibility to also hold mount options in sb's s_fs_info. This work implements mount options support for specifying permissions on the sb's inode, which will be used by tc when it manually needs to mount the fs. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/bpf')
-rw-r--r--kernel/bpf/inode.c54
1 files changed, 53 insertions, 1 deletions
diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c
index 2565809fbb34..0b030c9126d3 100644
--- a/kernel/bpf/inode.c
+++ b/kernel/bpf/inode.c
@@ -18,6 +18,7 @@
#include <linux/namei.h>
#include <linux/fs.h>
#include <linux/kdev_t.h>
+#include <linux/parser.h>
#include <linux/filter.h>
#include <linux/bpf.h>
@@ -364,15 +365,66 @@ static void bpf_evict_inode(struct inode *inode)
static const struct super_operations bpf_super_ops = {
.statfs = simple_statfs,
.drop_inode = generic_delete_inode,
+ .show_options = generic_show_options,
.evict_inode = bpf_evict_inode,
};
+enum {
+ OPT_MODE,
+ OPT_ERR,
+};
+
+static const match_table_t bpf_mount_tokens = {
+ { OPT_MODE, "mode=%o" },
+ { OPT_ERR, NULL },
+};
+
+struct bpf_mount_opts {
+ umode_t mode;
+};
+
+static int bpf_parse_options(char *data, struct bpf_mount_opts *opts)
+{
+ substring_t args[MAX_OPT_ARGS];
+ int option, token;
+ char *ptr;
+
+ opts->mode = S_IRWXUGO;
+
+ while ((ptr = strsep(&data, ",")) != NULL) {
+ if (!*ptr)
+ continue;
+
+ token = match_token(ptr, bpf_mount_tokens, args);
+ switch (token) {
+ case OPT_MODE:
+ if (match_octal(&args[0], &option))
+ return -EINVAL;
+ opts->mode = option & S_IALLUGO;
+ break;
+ /* We might like to report bad mount options here, but
+ * traditionally we've ignored all mount options, so we'd
+ * better continue to ignore non-existing options for bpf.
+ */
+ }
+ }
+
+ return 0;
+}
+
static int bpf_fill_super(struct super_block *sb, void *data, int silent)
{
static struct tree_descr bpf_rfiles[] = { { "" } };
+ struct bpf_mount_opts opts;
struct inode *inode;
int ret;
+ save_mount_options(sb, data);
+
+ ret = bpf_parse_options(data, &opts);
+ if (ret)
+ return ret;
+
ret = simple_fill_super(sb, BPF_FS_MAGIC, bpf_rfiles);
if (ret)
return ret;
@@ -382,7 +434,7 @@ static int bpf_fill_super(struct super_block *sb, void *data, int silent)
inode = sb->s_root->d_inode;
inode->i_op = &bpf_dir_iops;
inode->i_mode &= ~S_IALLUGO;
- inode->i_mode |= S_ISVTX | S_IRWXUGO;
+ inode->i_mode |= S_ISVTX | opts.mode;
return 0;
}