diff options
| -rw-r--r-- | include/linux/filter.h | 10 | ||||
| -rw-r--r-- | kernel/seccomp.c | 70 | ||||
| -rw-r--r-- | net/core/filter.c | 82 |
3 files changed, 91 insertions, 71 deletions
diff --git a/include/linux/filter.h b/include/linux/filter.h index fa11b3a367be..3c03a6085b82 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -363,9 +363,6 @@ int sk_filter(struct sock *sk, struct sk_buff *skb); void bpf_prog_select_runtime(struct bpf_prog *fp); void bpf_prog_free(struct bpf_prog *fp); -int bpf_convert_filter(struct sock_filter *prog, int len, - struct bpf_insn *new_prog, int *new_len); - struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags); struct bpf_prog *bpf_prog_realloc(struct bpf_prog *fp_old, unsigned int size, gfp_t gfp_extra_flags); @@ -377,14 +374,17 @@ static inline void bpf_prog_unlock_free(struct bpf_prog *fp) __bpf_prog_free(fp); } +typedef int (*bpf_aux_classic_check_t)(struct sock_filter *filter, + unsigned int flen); + int bpf_prog_create(struct bpf_prog **pfp, struct sock_fprog_kern *fprog); +int bpf_prog_create_from_user(struct bpf_prog **pfp, struct sock_fprog *fprog, + bpf_aux_classic_check_t trans); void bpf_prog_destroy(struct bpf_prog *fp); int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk); int sk_attach_bpf(u32 ufd, struct sock *sk); int sk_detach_filter(struct sock *sk); - -int bpf_check_classic(const struct sock_filter *filter, unsigned int flen); int sk_get_filter(struct sock *sk, struct sock_filter __user *filter, unsigned int len); diff --git a/kernel/seccomp.c b/kernel/seccomp.c index 4f44028943e6..245df6b32b81 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -346,16 +346,13 @@ static inline void seccomp_sync_threads(void) */ static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog) { - struct seccomp_filter *filter; - unsigned long fp_size; - struct sock_filter *fp; - int new_len; - long ret; + struct seccomp_filter *sfilter; + int ret; if (fprog->len == 0 || fprog->len > BPF_MAXINSNS) return ERR_PTR(-EINVAL); + BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter)); - fp_size = fprog->len * sizeof(struct sock_filter); /* * Installing a seccomp filter requires that the task has @@ -368,60 +365,21 @@ static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog) CAP_SYS_ADMIN) != 0) return ERR_PTR(-EACCES); - fp = kzalloc(fp_size, GFP_KERNEL|__GFP_NOWARN); - if (!fp) - return ERR_PTR(-ENOMEM); - - /* Copy the instructions from fprog. */ - ret = -EFAULT; - if (copy_from_user(fp, fprog->filter, fp_size)) - goto free_prog; - - /* Check and rewrite the fprog via the skb checker */ - ret = bpf_check_classic(fp, fprog->len); - if (ret) - goto free_prog; - - /* Check and rewrite the fprog for seccomp use */ - ret = seccomp_check_filter(fp, fprog->len); - if (ret) - goto free_prog; - - /* Convert 'sock_filter' insns to 'bpf_insn' insns */ - ret = bpf_convert_filter(fp, fprog->len, NULL, &new_len); - if (ret) - goto free_prog; - /* Allocate a new seccomp_filter */ - ret = -ENOMEM; - filter = kzalloc(sizeof(struct seccomp_filter), - GFP_KERNEL|__GFP_NOWARN); - if (!filter) - goto free_prog; - - filter->prog = bpf_prog_alloc(bpf_prog_size(new_len), __GFP_NOWARN); - if (!filter->prog) - goto free_filter; - - ret = bpf_convert_filter(fp, fprog->len, filter->prog->insnsi, &new_len); - if (ret) - goto free_filter_prog; - - kfree(fp); - atomic_set(&filter->usage, 1); - filter->prog->len = new_len; + sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL | __GFP_NOWARN); + if (!sfilter) + return ERR_PTR(-ENOMEM); - bpf_prog_select_runtime(filter->prog); + ret = bpf_prog_create_from_user(&sfilter->prog, fprog, + seccomp_check_filter); + if (ret < 0) { + kfree(sfilter); + return ERR_PTR(ret); + } - return filter; + atomic_set(&sfilter->usage, 1); -free_filter_prog: - __bpf_prog_free(filter->prog); -free_filter: - kfree(filter); -free_prog: - kfree(fp); - return ERR_PTR(ret); + return sfilter; } /** diff --git a/net/core/filter.c b/net/core/filter.c index bf831a85c315..a831f193e2c7 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -355,8 +355,8 @@ static bool convert_bpf_extensions(struct sock_filter *fp, * for socket filters: ctx == 'struct sk_buff *', for seccomp: * ctx == 'struct seccomp_data *'. */ -int bpf_convert_filter(struct sock_filter *prog, int len, - struct bpf_insn *new_prog, int *new_len) +static int bpf_convert_filter(struct sock_filter *prog, int len, + struct bpf_insn *new_prog, int *new_len) { int new_flen = 0, pass = 0, target, i; struct bpf_insn *new_insn; @@ -371,7 +371,8 @@ int bpf_convert_filter(struct sock_filter *prog, int len, return -EINVAL; if (new_prog) { - addrs = kcalloc(len, sizeof(*addrs), GFP_KERNEL); + addrs = kcalloc(len, sizeof(*addrs), + GFP_KERNEL | __GFP_NOWARN); if (!addrs) return -ENOMEM; } @@ -751,7 +752,8 @@ static bool chk_code_allowed(u16 code_to_probe) * * Returns 0 if the rule set is legal or -EINVAL if not. */ -int bpf_check_classic(const struct sock_filter *filter, unsigned int flen) +static int bpf_check_classic(const struct sock_filter *filter, + unsigned int flen) { bool anc_found; int pc; @@ -825,7 +827,6 @@ int bpf_check_classic(const struct sock_filter *filter, unsigned int flen) return -EINVAL; } -EXPORT_SYMBOL(bpf_check_classic); static int bpf_prog_store_orig_filter(struct bpf_prog *fp, const struct sock_fprog *fprog) @@ -839,7 +840,9 @@ static int bpf_prog_store_orig_filter(struct bpf_prog *fp, fkprog = fp->orig_prog; fkprog->len = fprog->len; - fkprog->filter = kmemdup(fp->insns, fsize, GFP_KERNEL); + + fkprog->filter = kmemdup(fp->insns, fsize, + GFP_KERNEL | __GFP_NOWARN); if (!fkprog->filter) { kfree(fp->orig_prog); return -ENOMEM; @@ -941,7 +944,7 @@ static struct bpf_prog *bpf_migrate_filter(struct bpf_prog *fp) * pass. At this time, the user BPF is stored in fp->insns. */ old_prog = kmemdup(fp->insns, old_len * sizeof(struct sock_filter), - GFP_KERNEL); + GFP_KERNEL | __GFP_NOWARN); if (!old_prog) { err = -ENOMEM; goto out_err; @@ -988,7 +991,8 @@ out_err: return ERR_PTR(err); } -static struct bpf_prog *bpf_prepare_filter(struct bpf_prog *fp) +static struct bpf_prog *bpf_prepare_filter(struct bpf_prog *fp, + bpf_aux_classic_check_t trans) { int err; @@ -1001,6 +1005,17 @@ static struct bpf_prog *bpf_prepare_filter(struct bpf_prog *fp) return ERR_PTR(err); } + /* There might be additional checks and transformations + * needed on classic filters, f.e. in case of seccomp. + */ + if (trans) { + err = trans(fp->insns, fp->len); + if (err) { + __bpf_prog_release(fp); + return ERR_PTR(err); + } + } + /* Probe if we can JIT compile the filter and if so, do * the compilation of the filter. */ @@ -1050,7 +1065,7 @@ int bpf_prog_create(struct bpf_prog **pfp, struct sock_fprog_kern *fprog) /* bpf_prepare_filter() already takes care of freeing * memory in case something goes wrong. */ - fp = bpf_prepare_filter(fp); + fp = bpf_prepare_filter(fp, NULL); if (IS_ERR(fp)) return PTR_ERR(fp); @@ -1059,6 +1074,53 @@ int bpf_prog_create(struct bpf_prog **pfp, struct sock_fprog_kern *fprog) } EXPORT_SYMBOL_GPL(bpf_prog_create); +/** + * bpf_prog_create_from_user - create an unattached filter from user buffer + * @pfp: the unattached filter that is created + * @fprog: the filter program + * @trans: post-classic verifier transformation handler + * + * This function effectively does the same as bpf_prog_create(), only + * that it builds up its insns buffer from user space provided buffer. + * It also allows for passing a bpf_aux_classic_check_t handler. + */ +int bpf_prog_create_from_user(struct bpf_prog **pfp, struct sock_fprog *fprog, + bpf_aux_classic_check_t trans) +{ + unsigned int fsize = bpf_classic_proglen(fprog); + struct bpf_prog *fp; + + /* Make sure new filter is there and in the right amounts. */ + if (fprog->filter == NULL) + return -EINVAL; + + fp = bpf_prog_alloc(bpf_prog_size(fprog->len), 0); + if (!fp) + return -ENOMEM; + + if (copy_from_user(fp->insns, fprog->filter, fsize)) { + __bpf_prog_free(fp); + return -EFAULT; + } + + fp->len = fprog->len; + /* Since unattached filters are not copied back to user + * space through sk_get_filter(), we do not need to hold + * a copy here, and can spare us the work. + */ + fp->orig_prog = NULL; + + /* bpf_prepare_filter() already takes care of freeing + * memory in case something goes wrong. + */ + fp = bpf_prepare_filter(fp, trans); + if (IS_ERR(fp)) + return PTR_ERR(fp); + + *pfp = fp; + return 0; +} + void bpf_prog_destroy(struct bpf_prog *fp) { __bpf_prog_release(fp); @@ -1135,7 +1197,7 @@ int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk) /* bpf_prepare_filter() already takes care of freeing * memory in case something goes wrong. */ - prog = bpf_prepare_filter(prog); + prog = bpf_prepare_filter(prog, NULL); if (IS_ERR(prog)) return PTR_ERR(prog); |