bpf: track stack depth of classic bpf programs (50bbfed9) · Commits · 戴 / test

net/core/filter.c

+22 −14

Original line number	Diff line number	Diff line
		@@ -352,7 +352,7 @@ static bool convert_bpf_extensions(struct sock_filter *fp,
		* bpf_convert_filter - convert filter program
		* @prog: the user passed filter program
		* @len: the length of the user passed filter program
		* @new_prog: buffer where converted program will be stored
		* @new_prog: allocated 'struct bpf_prog' or NULL
		* @new_len: pointer to store length of converted program
		*
		* Remap 'sock_filter' style classic BPF (cBPF) instruction set to 'bpf_insn'
		@@ -364,14 +364,13 @@ static bool convert_bpf_extensions(struct sock_filter *fp,
		*
		* 2) 2nd pass to remap in two passes: 1st pass finds new
		* jump offsets, 2nd pass remapping:
		* new_prog = kmalloc(sizeof(struct bpf_insn) * new_len);
		* bpf_convert_filter(old_prog, old_len, new_prog, &new_len);
		*/
		static int bpf_convert_filter(struct sock_filter *prog, int len,
		struct bpf_insn new_prog, int new_len)
		struct bpf_prog new_prog, int new_len)
		{
		int new_flen = 0, pass = 0, target, i;
		struct bpf_insn *new_insn;
		int new_flen = 0, pass = 0, target, i, stack_off;
		struct bpf_insn new_insn, first_insn = NULL;
		struct sock_filter *fp;
		int *addrs = NULL;
		u8 bpf_src;
		@@ -383,6 +382,7 @@ static int bpf_convert_filter(struct sock_filter *prog, int len,
		return -EINVAL;

		if (new_prog) {
		first_insn = new_prog->insnsi;
		addrs = kcalloc(len, sizeof(*addrs),
		GFP_KERNEL \| __GFP_NOWARN);
		if (!addrs)
		@@ -390,11 +390,11 @@ static int bpf_convert_filter(struct sock_filter *prog, int len,
		}

		do_pass:
		new_insn = new_prog;
		new_insn = first_insn;
		fp = prog;

		/* Classic BPF related prologue emission. */
		if (new_insn) {
		if (new_prog) {
		/* Classic BPF expects A and X to be reset first. These need
		* to be guaranteed to be the first two instructions.
		*/
		@@ -415,7 +415,7 @@ do_pass:
		struct bpf_insn *insn = tmp_insns;

		if (addrs)
		addrs[i] = new_insn - new_prog;
		addrs[i] = new_insn - first_insn;

		switch (fp->code) {
		/* All arithmetic insns and skb loads map as-is. */
		@@ -561,17 +561,25 @@ do_pass:
		/* Store to stack. */
		case BPF_ST:
		case BPF_STX:
		stack_off = fp->k * 4 + 4;
		*insn = BPF_STX_MEM(BPF_W, BPF_REG_FP, BPF_CLASS(fp->code) ==
		BPF_ST ? BPF_REG_A : BPF_REG_X,
		-(BPF_MEMWORDS - fp->k) * 4);
		-stack_off);
		/* check_load_and_stores() verifies that classic BPF can
		* load from stack only after write, so tracking
		* stack_depth for ST\|STX insns is enough
		*/
		if (new_prog && new_prog->aux->stack_depth < stack_off)
		new_prog->aux->stack_depth = stack_off;
		break;

		/* Load from stack. */
		case BPF_LD \| BPF_MEM:
		case BPF_LDX \| BPF_MEM:
		stack_off = fp->k * 4 + 4;
		*insn = BPF_LDX_MEM(BPF_W, BPF_CLASS(fp->code) == BPF_LD ?
		BPF_REG_A : BPF_REG_X, BPF_REG_FP,
		-(BPF_MEMWORDS - fp->k) * 4);
		-stack_off);
		break;

		/* A = K or X = K */
		@@ -619,13 +627,13 @@ do_pass:

		if (!new_prog) {
		/* Only calculating new length. */
		*new_len = new_insn - new_prog;
		*new_len = new_insn - first_insn;
		return 0;
		}

		pass++;
		if (new_flen != new_insn - new_prog) {
		new_flen = new_insn - new_prog;
		if (new_flen != new_insn - first_insn) {
		new_flen = new_insn - first_insn;
		if (pass > 2)
		goto err;
		goto do_pass;
		@@ -1017,7 +1025,7 @@ static struct bpf_prog bpf_migrate_filter(struct bpf_prog fp)
		fp->len = new_len;

		/* 2nd pass: remap sock_filter insns into bpf_insn insns. */
		err = bpf_convert_filter(old_prog, old_len, fp->insnsi, &new_len);
		err = bpf_convert_filter(old_prog, old_len, fp, &new_len);
		if (err)
		/* 2nd bpf_convert_filter() can fail only if it fails
		* to allocate memory, remapping must succeed. Note,

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