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ospfd: validate input SRGB and SRLB

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The code was not checking if in these label ranges [a,b], a is
smaller than b, which is assumed in several places, including when
determining the size of the block as b-a+1. As a consequence, the
results of a bad configuration can be unpredictable. Some effects
observed were: 1) segfault 2) de-activation of SR due to label
reservation failure.

The added validation function also checks if the SR blocks are
larger than some minimal size. RFC 8665 mandates that the blocks
be srictly larger than zero. In this patch, the minimum sized is
arbitrarily defined to be 16.

Checking if ranges would fall outside [16,1048575] is omitted
since the vty filtering takes care of that.

Signed-off-by: Fredi Raspall <fredi@voltanet.io>
This commit is contained in:
Fredi Raspall 2021-05-28 23:06:50 +02:00 committed by Emanuele Di Pascale
parent e90c038324
commit 6c57d01073
2 changed files with 29 additions and 0 deletions
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26
ospfd/ospf_sr.c
View File

@ -2151,6 +2151,13 @@ static bool ranges_overlap(uint32_t r1_lower, uint32_t r1_upper,
return !((r1_upper < r2_lower) || (r1_lower > r2_upper));
}
/* tell if a range is valid */
static bool sr_range_is_valid(uint32_t lower, uint32_t upper, uint32_t min_size)
{
return (upper >= lower + min_size);
}
/**
* Update SRGB and/or SRLB using new CLI values.
*
@ -2268,12 +2275,25 @@ DEFUN(sr_global_label_range, sr_global_label_range_cmd,
/* Get lower and upper bound for mandatory global-block */
gb_lower = strtoul(argv[idx_gb_low]->arg, NULL, 10);
gb_upper = strtoul(argv[idx_gb_up]->arg, NULL, 10);
/* SRLB values are taken from vtysh if there, else use the known ones */
lb_upper = argc > idx_lb_up ? strtoul(argv[idx_lb_up]->arg, NULL, 10)
: OspfSR.srlb.end;
lb_lower = argc > idx_lb_low ? strtoul(argv[idx_lb_low]->arg, NULL, 10)
: OspfSR.srlb.start;
/* check correctness of input SRGB */
if (!sr_range_is_valid(gb_lower, gb_upper, MIN_SRGB_SIZE)) {
vty_out(vty, "Invalid SRGB range\n");
return CMD_WARNING_CONFIG_FAILED;
}
/* check correctness of SRLB */
if (!sr_range_is_valid(lb_lower, lb_upper, MIN_SRLB_SIZE)) {
vty_out(vty, "Invalid SRLB range\n");
return CMD_WARNING_CONFIG_FAILED;
}
/* Validate SRGB against SRLB */
if (ranges_overlap(gb_lower, gb_upper, lb_lower, lb_upper)) {
vty_out(vty,
@ -2328,6 +2348,12 @@ DEFUN_HIDDEN(sr_local_label_range, sr_local_label_range_cmd,
lower = strtoul(argv[idx_low]->arg, NULL, 10);
upper = strtoul(argv[idx_up]->arg, NULL, 10);
/* check correctness of SRLB */
if (!sr_range_is_valid(lower, upper, MIN_SRLB_SIZE)) {
vty_out(vty, "Invalid SRLB range\n");
return CMD_WARNING_CONFIG_FAILED;
}
/* Check if values have changed */
if ((OspfSR.srlb.start == lower)
&& (OspfSR.srlb.end == upper))

3
ospfd/ospf_sr.h
View File

@ -38,6 +38,9 @@
#define SET_LABEL(label) ((label << 8) & SET_LABEL_MASK)
#define GET_LABEL(label) ((label >> 8) & GET_LABEL_MASK)
/* smallest configurable SRGB / SRLB sizes */
#define MIN_SRLB_SIZE 16
#define MIN_SRGB_SIZE 16
/* Segment Routing TLVs as per RFC 8665 */